It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp
new file mode 100644
index 0000000..520cfeb
--- /dev/null
+++ b/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -0,0 +1,175 @@
+//===-- BasicBlockUtils.cpp - BasicBlock Utilities -------------------------==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This family of functions perform manipulations on basic blocks, and
+// instructions contained within basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Constant.h"
+#include "llvm/Type.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/Dominators.h"
+#include <algorithm>
+using namespace llvm;
+
+/// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
+/// with a value, then remove and delete the original instruction.
+///
+void llvm::ReplaceInstWithValue(BasicBlock::InstListType &BIL,
+ BasicBlock::iterator &BI, Value *V) {
+ Instruction &I = *BI;
+ // Replaces all of the uses of the instruction with uses of the value
+ I.replaceAllUsesWith(V);
+
+ // Make sure to propagate a name if there is one already.
+ if (I.hasName() && !V->hasName())
+ V->takeName(&I);
+
+ // Delete the unnecessary instruction now...
+ BI = BIL.erase(BI);
+}
+
+
+/// ReplaceInstWithInst - Replace the instruction specified by BI with the
+/// instruction specified by I. The original instruction is deleted and BI is
+/// updated to point to the new instruction.
+///
+void llvm::ReplaceInstWithInst(BasicBlock::InstListType &BIL,
+ BasicBlock::iterator &BI, Instruction *I) {
+ assert(I->getParent() == 0 &&
+ "ReplaceInstWithInst: Instruction already inserted into basic block!");
+
+ // Insert the new instruction into the basic block...
+ BasicBlock::iterator New = BIL.insert(BI, I);
+
+ // Replace all uses of the old instruction, and delete it.
+ ReplaceInstWithValue(BIL, BI, I);
+
+ // Move BI back to point to the newly inserted instruction
+ BI = New;
+}
+
+/// ReplaceInstWithInst - Replace the instruction specified by From with the
+/// instruction specified by To.
+///
+void llvm::ReplaceInstWithInst(Instruction *From, Instruction *To) {
+ BasicBlock::iterator BI(From);
+ ReplaceInstWithInst(From->getParent()->getInstList(), BI, To);
+}
+
+/// RemoveSuccessor - Change the specified terminator instruction such that its
+/// successor SuccNum no longer exists. Because this reduces the outgoing
+/// degree of the current basic block, the actual terminator instruction itself
+/// may have to be changed. In the case where the last successor of the block
+/// is deleted, a return instruction is inserted in its place which can cause a
+/// surprising change in program behavior if it is not expected.
+///
+void llvm::RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum) {
+ assert(SuccNum < TI->getNumSuccessors() &&
+ "Trying to remove a nonexistant successor!");
+
+ // If our old successor block contains any PHI nodes, remove the entry in the
+ // PHI nodes that comes from this branch...
+ //
+ BasicBlock *BB = TI->getParent();
+ TI->getSuccessor(SuccNum)->removePredecessor(BB);
+
+ TerminatorInst *NewTI = 0;
+ switch (TI->getOpcode()) {
+ case Instruction::Br:
+ // If this is a conditional branch... convert to unconditional branch.
+ if (TI->getNumSuccessors() == 2) {
+ cast<BranchInst>(TI)->setUnconditionalDest(TI->getSuccessor(1-SuccNum));
+ } else { // Otherwise convert to a return instruction...
+ Value *RetVal = 0;
+
+ // Create a value to return... if the function doesn't return null...
+ if (BB->getParent()->getReturnType() != Type::VoidTy)
+ RetVal = Constant::getNullValue(BB->getParent()->getReturnType());
+
+ // Create the return...
+ NewTI = new ReturnInst(RetVal);
+ }
+ break;
+
+ case Instruction::Invoke: // Should convert to call
+ case Instruction::Switch: // Should remove entry
+ default:
+ case Instruction::Ret: // Cannot happen, has no successors!
+ assert(0 && "Unhandled terminator instruction type in RemoveSuccessor!");
+ abort();
+ }
+
+ if (NewTI) // If it's a different instruction, replace.
+ ReplaceInstWithInst(TI, NewTI);
+}
+
+/// SplitEdge - Split the edge connecting specified block. Pass P must
+/// not be NULL.
+BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) {
+ TerminatorInst *LatchTerm = BB->getTerminator();
+ unsigned SuccNum = 0;
+ for (unsigned i = 0, e = LatchTerm->getNumSuccessors(); ; ++i) {
+ assert(i != e && "Didn't find edge?");
+ if (LatchTerm->getSuccessor(i) == Succ) {
+ SuccNum = i;
+ break;
+ }
+ }
+
+ // If this is a critical edge, let SplitCriticalEdge do it.
+ if (SplitCriticalEdge(BB->getTerminator(), SuccNum, P))
+ return LatchTerm->getSuccessor(SuccNum);
+
+ // If the edge isn't critical, then BB has a single successor or Succ has a
+ // single pred. Split the block.
+ BasicBlock::iterator SplitPoint;
+ if (BasicBlock *SP = Succ->getSinglePredecessor()) {
+ // If the successor only has a single pred, split the top of the successor
+ // block.
+ assert(SP == BB && "CFG broken");
+ return SplitBlock(Succ, Succ->begin(), P);
+ } else {
+ // Otherwise, if BB has a single successor, split it at the bottom of the
+ // block.
+ assert(BB->getTerminator()->getNumSuccessors() == 1 &&
+ "Should have a single succ!");
+ return SplitBlock(BB, BB->getTerminator(), P);
+ }
+}
+
+/// SplitBlock - Split the specified block at the specified instruction - every
+/// thing before SplitPt stays in Old and everything starting with SplitPt moves
+/// to a new block. The two blocks are joined by an unconditional branch and
+/// the loop info is updated.
+///
+BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P) {
+
+ LoopInfo &LI = P->getAnalysis<LoopInfo>();
+ BasicBlock::iterator SplitIt = SplitPt;
+ while (isa<PHINode>(SplitIt))
+ ++SplitIt;
+ BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split");
+
+ // The new block lives in whichever loop the old one did.
+ if (Loop *L = LI.getLoopFor(Old))
+ L->addBasicBlockToLoop(New, LI);
+
+ if (DominatorTree *DT = P->getAnalysisToUpdate<DominatorTree>())
+ DT->addNewBlock(New, Old);
+
+ if (DominanceFrontier *DF = P->getAnalysisToUpdate<DominanceFrontier>())
+ DF->splitBlock(Old);
+
+ return New;
+}
diff --git a/lib/Transforms/Utils/BreakCriticalEdges.cpp b/lib/Transforms/Utils/BreakCriticalEdges.cpp
new file mode 100644
index 0000000..af9a114
--- /dev/null
+++ b/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -0,0 +1,269 @@
+//===- BreakCriticalEdges.cpp - Critical Edge Elimination Pass ------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// BreakCriticalEdges pass - Break all of the critical edges in the CFG by
+// inserting a dummy basic block. This pass may be "required" by passes that
+// cannot deal with critical edges. For this usage, the structure type is
+// forward declared. This pass obviously invalidates the CFG, but can update
+// forward dominator (set, immediate dominators, tree, and frontier)
+// information.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "break-crit-edges"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+using namespace llvm;
+
+STATISTIC(NumBroken, "Number of blocks inserted");
+
+namespace {
+ struct VISIBILITY_HIDDEN BreakCriticalEdges : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ BreakCriticalEdges() : FunctionPass((intptr_t)&ID) {}
+
+ virtual bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addPreserved<DominatorTree>();
+ AU.addPreserved<DominanceFrontier>();
+ AU.addPreserved<LoopInfo>();
+
+ // No loop canonicalization guarantees are broken by this pass.
+ AU.addPreservedID(LoopSimplifyID);
+ }
+ };
+
+ char BreakCriticalEdges::ID = 0;
+ RegisterPass<BreakCriticalEdges> X("break-crit-edges",
+ "Break critical edges in CFG");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::BreakCriticalEdgesID = X.getPassInfo();
+FunctionPass *llvm::createBreakCriticalEdgesPass() {
+ return new BreakCriticalEdges();
+}
+
+// runOnFunction - Loop over all of the edges in the CFG, breaking critical
+// edges as they are found.
+//
+bool BreakCriticalEdges::runOnFunction(Function &F) {
+ bool Changed = false;
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+ TerminatorInst *TI = I->getTerminator();
+ if (TI->getNumSuccessors() > 1)
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ if (SplitCriticalEdge(TI, i, this)) {
+ ++NumBroken;
+ Changed = true;
+ }
+ }
+
+ return Changed;
+}
+
+//===----------------------------------------------------------------------===//
+// Implementation of the external critical edge manipulation functions
+//===----------------------------------------------------------------------===//
+
+// isCriticalEdge - Return true if the specified edge is a critical edge.
+// Critical edges are edges from a block with multiple successors to a block
+// with multiple predecessors.
+//
+bool llvm::isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
+ bool AllowIdenticalEdges) {
+ assert(SuccNum < TI->getNumSuccessors() && "Illegal edge specification!");
+ if (TI->getNumSuccessors() == 1) return false;
+
+ const BasicBlock *Dest = TI->getSuccessor(SuccNum);
+ pred_const_iterator I = pred_begin(Dest), E = pred_end(Dest);
+
+ // If there is more than one predecessor, this is a critical edge...
+ assert(I != E && "No preds, but we have an edge to the block?");
+ const BasicBlock *FirstPred = *I;
+ ++I; // Skip one edge due to the incoming arc from TI.
+ if (!AllowIdenticalEdges)
+ return I != E;
+
+ // If AllowIdenticalEdges is true, then we allow this edge to be considered
+ // non-critical iff all preds come from TI's block.
+ for (; I != E; ++I)
+ if (*I != FirstPred) return true;
+ return false;
+}
+
+// SplitCriticalEdge - If this edge is a critical edge, insert a new node to
+// split the critical edge. This will update DominatorTree, and DominatorFrontier
+// information if it is available, thus calling this pass will not invalidate
+// any of them. This returns true if the edge was split, false otherwise.
+// This ensures that all edges to that dest go to one block instead of each
+// going to a different block.
+//
+bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P,
+ bool MergeIdenticalEdges) {
+ if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return false;
+ BasicBlock *TIBB = TI->getParent();
+ BasicBlock *DestBB = TI->getSuccessor(SuccNum);
+
+ // Create a new basic block, linking it into the CFG.
+ BasicBlock *NewBB = new BasicBlock(TIBB->getName() + "." +
+ DestBB->getName() + "_crit_edge");
+ // Create our unconditional branch...
+ new BranchInst(DestBB, NewBB);
+
+ // Branch to the new block, breaking the edge.
+ TI->setSuccessor(SuccNum, NewBB);
+
+ // Insert the block into the function... right after the block TI lives in.
+ Function &F = *TIBB->getParent();
+ Function::iterator FBBI = TIBB;
+ F.getBasicBlockList().insert(++FBBI, NewBB);
+
+ // If there are any PHI nodes in DestBB, we need to update them so that they
+ // merge incoming values from NewBB instead of from TIBB.
+ //
+ for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ // We no longer enter through TIBB, now we come in through NewBB. Revector
+ // exactly one entry in the PHI node that used to come from TIBB to come
+ // from NewBB.
+ int BBIdx = PN->getBasicBlockIndex(TIBB);
+ PN->setIncomingBlock(BBIdx, NewBB);
+ }
+
+ // If there are any other edges from TIBB to DestBB, update those to go
+ // through the split block, making those edges non-critical as well (and
+ // reducing the number of phi entries in the DestBB if relevant).
+ if (MergeIdenticalEdges) {
+ for (unsigned i = SuccNum+1, e = TI->getNumSuccessors(); i != e; ++i) {
+ if (TI->getSuccessor(i) != DestBB) continue;
+
+ // Remove an entry for TIBB from DestBB phi nodes.
+ DestBB->removePredecessor(TIBB);
+
+ // We found another edge to DestBB, go to NewBB instead.
+ TI->setSuccessor(i, NewBB);
+ }
+ }
+
+
+
+ // If we don't have a pass object, we can't update anything...
+ if (P == 0) return true;
+
+ // Now update analysis information. Since the only predecessor of NewBB is
+ // the TIBB, TIBB clearly dominates NewBB. TIBB usually doesn't dominate
+ // anything, as there are other successors of DestBB. However, if all other
+ // predecessors of DestBB are already dominated by DestBB (e.g. DestBB is a
+ // loop header) then NewBB dominates DestBB.
+ SmallVector<BasicBlock*, 8> OtherPreds;
+
+ for (pred_iterator I = pred_begin(DestBB), E = pred_end(DestBB); I != E; ++I)
+ if (*I != NewBB)
+ OtherPreds.push_back(*I);
+
+ bool NewBBDominatesDestBB = true;
+
+ // Should we update DominatorTree information?
+ if (DominatorTree *DT = P->getAnalysisToUpdate<DominatorTree>()) {
+ DomTreeNode *TINode = DT->getNode(TIBB);
+
+ // The new block is not the immediate dominator for any other nodes, but
+ // TINode is the immediate dominator for the new node.
+ //
+ if (TINode) { // Don't break unreachable code!
+ DomTreeNode *NewBBNode = DT->addNewBlock(NewBB, TIBB);
+ DomTreeNode *DestBBNode = 0;
+
+ // If NewBBDominatesDestBB hasn't been computed yet, do so with DT.
+ if (!OtherPreds.empty()) {
+ DestBBNode = DT->getNode(DestBB);
+ while (!OtherPreds.empty() && NewBBDominatesDestBB) {
+ if (DomTreeNode *OPNode = DT->getNode(OtherPreds.back()))
+ NewBBDominatesDestBB = DT->dominates(DestBBNode, OPNode);
+ OtherPreds.pop_back();
+ }
+ OtherPreds.clear();
+ }
+
+ // If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
+ // doesn't dominate anything.
+ if (NewBBDominatesDestBB) {
+ if (!DestBBNode) DestBBNode = DT->getNode(DestBB);
+ DT->changeImmediateDominator(DestBBNode, NewBBNode);
+ }
+ }
+ }
+
+ // Should we update DominanceFrontier information?
+ if (DominanceFrontier *DF = P->getAnalysisToUpdate<DominanceFrontier>()) {
+ // If NewBBDominatesDestBB hasn't been computed yet, do so with DF.
+ if (!OtherPreds.empty()) {
+ // FIXME: IMPLEMENT THIS!
+ assert(0 && "Requiring domfrontiers but not idom/domtree/domset."
+ " not implemented yet!");
+ }
+
+ // Since the new block is dominated by its only predecessor TIBB,
+ // it cannot be in any block's dominance frontier. If NewBB dominates
+ // DestBB, its dominance frontier is the same as DestBB's, otherwise it is
+ // just {DestBB}.
+ DominanceFrontier::DomSetType NewDFSet;
+ if (NewBBDominatesDestBB) {
+ DominanceFrontier::iterator I = DF->find(DestBB);
+ if (I != DF->end())
+ DF->addBasicBlock(NewBB, I->second);
+ else
+ DF->addBasicBlock(NewBB, DominanceFrontier::DomSetType());
+ } else {
+ DominanceFrontier::DomSetType NewDFSet;
+ NewDFSet.insert(DestBB);
+ DF->addBasicBlock(NewBB, NewDFSet);
+ }
+ }
+
+ // Update LoopInfo if it is around.
+ if (LoopInfo *LI = P->getAnalysisToUpdate<LoopInfo>()) {
+ // If one or the other blocks were not in a loop, the new block is not
+ // either, and thus LI doesn't need to be updated.
+ if (Loop *TIL = LI->getLoopFor(TIBB))
+ if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
+ if (TIL == DestLoop) {
+ // Both in the same loop, the NewBB joins loop.
+ DestLoop->addBasicBlockToLoop(NewBB, *LI);
+ } else if (TIL->contains(DestLoop->getHeader())) {
+ // Edge from an outer loop to an inner loop. Add to the outer loop.
+ TIL->addBasicBlockToLoop(NewBB, *LI);
+ } else if (DestLoop->contains(TIL->getHeader())) {
+ // Edge from an inner loop to an outer loop. Add to the outer loop.
+ DestLoop->addBasicBlockToLoop(NewBB, *LI);
+ } else {
+ // Edge from two loops with no containment relation. Because these
+ // are natural loops, we know that the destination block must be the
+ // header of its loop (adding a branch into a loop elsewhere would
+ // create an irreducible loop).
+ assert(DestLoop->getHeader() == DestBB &&
+ "Should not create irreducible loops!");
+ if (Loop *P = DestLoop->getParentLoop())
+ P->addBasicBlockToLoop(NewBB, *LI);
+ }
+ }
+ }
+ return true;
+}
diff --git a/lib/Transforms/Utils/CloneFunction.cpp b/lib/Transforms/Utils/CloneFunction.cpp
new file mode 100644
index 0000000..cff58ab
--- /dev/null
+++ b/lib/Transforms/Utils/CloneFunction.cpp
@@ -0,0 +1,485 @@
+//===- CloneFunction.cpp - Clone a function into another function ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the CloneFunctionInto interface, which is used as the
+// low-level function cloner. This is used by the CloneFunction and function
+// inliner to do the dirty work of copying the body of a function around.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include "ValueMapper.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/ADT/SmallVector.h"
+#include <map>
+using namespace llvm;
+
+// CloneBasicBlock - See comments in Cloning.h
+BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB,
+ DenseMap<const Value*, Value*> &ValueMap,
+ const char *NameSuffix, Function *F,
+ ClonedCodeInfo *CodeInfo) {
+ BasicBlock *NewBB = new BasicBlock("", F);
+ if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
+
+ bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
+
+ // Loop over all instructions, and copy them over.
+ for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
+ II != IE; ++II) {
+ Instruction *NewInst = II->clone();
+ if (II->hasName())
+ NewInst->setName(II->getName()+NameSuffix);
+ NewBB->getInstList().push_back(NewInst);
+ ValueMap[II] = NewInst; // Add instruction map to value.
+
+ hasCalls |= isa<CallInst>(II);
+ if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
+ if (isa<ConstantInt>(AI->getArraySize()))
+ hasStaticAllocas = true;
+ else
+ hasDynamicAllocas = true;
+ }
+ }
+
+ if (CodeInfo) {
+ CodeInfo->ContainsCalls |= hasCalls;
+ CodeInfo->ContainsUnwinds |= isa<UnwindInst>(BB->getTerminator());
+ CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
+ CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
+ BB != &BB->getParent()->getEntryBlock();
+ }
+ return NewBB;
+}
+
+// Clone OldFunc into NewFunc, transforming the old arguments into references to
+// ArgMap values.
+//
+void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
+ DenseMap<const Value*, Value*> &ValueMap,
+ std::vector<ReturnInst*> &Returns,
+ const char *NameSuffix, ClonedCodeInfo *CodeInfo) {
+ assert(NameSuffix && "NameSuffix cannot be null!");
+
+#ifndef NDEBUG
+ for (Function::const_arg_iterator I = OldFunc->arg_begin(),
+ E = OldFunc->arg_end(); I != E; ++I)
+ assert(ValueMap.count(I) && "No mapping from source argument specified!");
+#endif
+
+ // Loop over all of the basic blocks in the function, cloning them as
+ // appropriate. Note that we save BE this way in order to handle cloning of
+ // recursive functions into themselves.
+ //
+ for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
+ BI != BE; ++BI) {
+ const BasicBlock &BB = *BI;
+
+ // Create a new basic block and copy instructions into it!
+ BasicBlock *CBB = CloneBasicBlock(&BB, ValueMap, NameSuffix, NewFunc,
+ CodeInfo);
+ ValueMap[&BB] = CBB; // Add basic block mapping.
+
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
+ Returns.push_back(RI);
+ }
+
+ // Loop over all of the instructions in the function, fixing up operand
+ // references as we go. This uses ValueMap to do all the hard work.
+ //
+ for (Function::iterator BB = cast<BasicBlock>(ValueMap[OldFunc->begin()]),
+ BE = NewFunc->end(); BB != BE; ++BB)
+ // Loop over all instructions, fixing each one as we find it...
+ for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
+ RemapInstruction(II, ValueMap);
+}
+
+/// CloneFunction - Return a copy of the specified function, but without
+/// embedding the function into another module. Also, any references specified
+/// in the ValueMap are changed to refer to their mapped value instead of the
+/// original one. If any of the arguments to the function are in the ValueMap,
+/// the arguments are deleted from the resultant function. The ValueMap is
+/// updated to include mappings from all of the instructions and basicblocks in
+/// the function from their old to new values.
+///
+Function *llvm::CloneFunction(const Function *F,
+ DenseMap<const Value*, Value*> &ValueMap,
+ ClonedCodeInfo *CodeInfo) {
+ std::vector<const Type*> ArgTypes;
+
+ // The user might be deleting arguments to the function by specifying them in
+ // the ValueMap. If so, we need to not add the arguments to the arg ty vector
+ //
+ for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
+ I != E; ++I)
+ if (ValueMap.count(I) == 0) // Haven't mapped the argument to anything yet?
+ ArgTypes.push_back(I->getType());
+
+ // Create a new function type...
+ FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
+ ArgTypes, F->getFunctionType()->isVarArg());
+
+ // Create the new function...
+ Function *NewF = new Function(FTy, F->getLinkage(), F->getName());
+
+ // Loop over the arguments, copying the names of the mapped arguments over...
+ Function::arg_iterator DestI = NewF->arg_begin();
+ for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
+ I != E; ++I)
+ if (ValueMap.count(I) == 0) { // Is this argument preserved?
+ DestI->setName(I->getName()); // Copy the name over...
+ ValueMap[I] = DestI++; // Add mapping to ValueMap
+ }
+
+ std::vector<ReturnInst*> Returns; // Ignore returns cloned...
+ CloneFunctionInto(NewF, F, ValueMap, Returns, "", CodeInfo);
+ return NewF;
+}
+
+
+
+namespace {
+ /// PruningFunctionCloner - This class is a private class used to implement
+ /// the CloneAndPruneFunctionInto method.
+ struct VISIBILITY_HIDDEN PruningFunctionCloner {
+ Function *NewFunc;
+ const Function *OldFunc;
+ DenseMap<const Value*, Value*> &ValueMap;
+ std::vector<ReturnInst*> &Returns;
+ const char *NameSuffix;
+ ClonedCodeInfo *CodeInfo;
+ const TargetData *TD;
+
+ public:
+ PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
+ DenseMap<const Value*, Value*> &valueMap,
+ std::vector<ReturnInst*> &returns,
+ const char *nameSuffix,
+ ClonedCodeInfo *codeInfo,
+ const TargetData *td)
+ : NewFunc(newFunc), OldFunc(oldFunc), ValueMap(valueMap), Returns(returns),
+ NameSuffix(nameSuffix), CodeInfo(codeInfo), TD(td) {
+ }
+
+ /// CloneBlock - The specified block is found to be reachable, clone it and
+ /// anything that it can reach.
+ void CloneBlock(const BasicBlock *BB,
+ std::vector<const BasicBlock*> &ToClone);
+
+ public:
+ /// ConstantFoldMappedInstruction - Constant fold the specified instruction,
+ /// mapping its operands through ValueMap if they are available.
+ Constant *ConstantFoldMappedInstruction(const Instruction *I);
+ };
+}
+
+/// CloneBlock - The specified block is found to be reachable, clone it and
+/// anything that it can reach.
+void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
+ std::vector<const BasicBlock*> &ToClone){
+ Value *&BBEntry = ValueMap[BB];
+
+ // Have we already cloned this block?
+ if (BBEntry) return;
+
+ // Nope, clone it now.
+ BasicBlock *NewBB;
+ BBEntry = NewBB = new BasicBlock();
+ if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
+
+ bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
+
+ // Loop over all instructions, and copy them over, DCE'ing as we go. This
+ // loop doesn't include the terminator.
+ for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
+ II != IE; ++II) {
+ // If this instruction constant folds, don't bother cloning the instruction,
+ // instead, just add the constant to the value map.
+ if (Constant *C = ConstantFoldMappedInstruction(II)) {
+ ValueMap[II] = C;
+ continue;
+ }
+
+ Instruction *NewInst = II->clone();
+ if (II->hasName())
+ NewInst->setName(II->getName()+NameSuffix);
+ NewBB->getInstList().push_back(NewInst);
+ ValueMap[II] = NewInst; // Add instruction map to value.
+
+ hasCalls |= isa<CallInst>(II);
+ if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
+ if (isa<ConstantInt>(AI->getArraySize()))
+ hasStaticAllocas = true;
+ else
+ hasDynamicAllocas = true;
+ }
+ }
+
+ // Finally, clone over the terminator.
+ const TerminatorInst *OldTI = BB->getTerminator();
+ bool TerminatorDone = false;
+ if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
+ if (BI->isConditional()) {
+ // If the condition was a known constant in the callee...
+ ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
+ // Or is a known constant in the caller...
+ if (Cond == 0)
+ Cond = dyn_cast_or_null<ConstantInt>(ValueMap[BI->getCondition()]);
+
+ // Constant fold to uncond branch!
+ if (Cond) {
+ BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
+ ValueMap[OldTI] = new BranchInst(Dest, NewBB);
+ ToClone.push_back(Dest);
+ TerminatorDone = true;
+ }
+ }
+ } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
+ // If switching on a value known constant in the caller.
+ ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
+ if (Cond == 0) // Or known constant after constant prop in the callee...
+ Cond = dyn_cast_or_null<ConstantInt>(ValueMap[SI->getCondition()]);
+ if (Cond) { // Constant fold to uncond branch!
+ BasicBlock *Dest = SI->getSuccessor(SI->findCaseValue(Cond));
+ ValueMap[OldTI] = new BranchInst(Dest, NewBB);
+ ToClone.push_back(Dest);
+ TerminatorDone = true;
+ }
+ }
+
+ if (!TerminatorDone) {
+ Instruction *NewInst = OldTI->clone();
+ if (OldTI->hasName())
+ NewInst->setName(OldTI->getName()+NameSuffix);
+ NewBB->getInstList().push_back(NewInst);
+ ValueMap[OldTI] = NewInst; // Add instruction map to value.
+
+ // Recursively clone any reachable successor blocks.
+ const TerminatorInst *TI = BB->getTerminator();
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ ToClone.push_back(TI->getSuccessor(i));
+ }
+
+ if (CodeInfo) {
+ CodeInfo->ContainsCalls |= hasCalls;
+ CodeInfo->ContainsUnwinds |= isa<UnwindInst>(OldTI);
+ CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
+ CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
+ BB != &BB->getParent()->front();
+ }
+
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(NewBB->getTerminator()))
+ Returns.push_back(RI);
+}
+
+/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
+/// mapping its operands through ValueMap if they are available.
+Constant *PruningFunctionCloner::
+ConstantFoldMappedInstruction(const Instruction *I) {
+ SmallVector<Constant*, 8> Ops;
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (Constant *Op = dyn_cast_or_null<Constant>(MapValue(I->getOperand(i),
+ ValueMap)))
+ Ops.push_back(Op);
+ else
+ return 0; // All operands not constant!
+
+ return ConstantFoldInstOperands(I, &Ops[0], Ops.size(), TD);
+}
+
+/// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
+/// except that it does some simple constant prop and DCE on the fly. The
+/// effect of this is to copy significantly less code in cases where (for
+/// example) a function call with constant arguments is inlined, and those
+/// constant arguments cause a significant amount of code in the callee to be
+/// dead. Since this doesn't produce an exactly copy of the input, it can't be
+/// used for things like CloneFunction or CloneModule.
+void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
+ DenseMap<const Value*, Value*> &ValueMap,
+ std::vector<ReturnInst*> &Returns,
+ const char *NameSuffix,
+ ClonedCodeInfo *CodeInfo,
+ const TargetData *TD) {
+ assert(NameSuffix && "NameSuffix cannot be null!");
+
+#ifndef NDEBUG
+ for (Function::const_arg_iterator II = OldFunc->arg_begin(),
+ E = OldFunc->arg_end(); II != E; ++II)
+ assert(ValueMap.count(II) && "No mapping from source argument specified!");
+#endif
+
+ PruningFunctionCloner PFC(NewFunc, OldFunc, ValueMap, Returns,
+ NameSuffix, CodeInfo, TD);
+
+ // Clone the entry block, and anything recursively reachable from it.
+ std::vector<const BasicBlock*> CloneWorklist;
+ CloneWorklist.push_back(&OldFunc->getEntryBlock());
+ while (!CloneWorklist.empty()) {
+ const BasicBlock *BB = CloneWorklist.back();
+ CloneWorklist.pop_back();
+ PFC.CloneBlock(BB, CloneWorklist);
+ }
+
+ // Loop over all of the basic blocks in the old function. If the block was
+ // reachable, we have cloned it and the old block is now in the value map:
+ // insert it into the new function in the right order. If not, ignore it.
+ //
+ // Defer PHI resolution until rest of function is resolved.
+ std::vector<const PHINode*> PHIToResolve;
+ for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
+ BI != BE; ++BI) {
+ BasicBlock *NewBB = cast_or_null<BasicBlock>(ValueMap[BI]);
+ if (NewBB == 0) continue; // Dead block.
+
+ // Add the new block to the new function.
+ NewFunc->getBasicBlockList().push_back(NewBB);
+
+ // Loop over all of the instructions in the block, fixing up operand
+ // references as we go. This uses ValueMap to do all the hard work.
+ //
+ BasicBlock::iterator I = NewBB->begin();
+
+ // Handle PHI nodes specially, as we have to remove references to dead
+ // blocks.
+ if (PHINode *PN = dyn_cast<PHINode>(I)) {
+ // Skip over all PHI nodes, remembering them for later.
+ BasicBlock::const_iterator OldI = BI->begin();
+ for (; (PN = dyn_cast<PHINode>(I)); ++I, ++OldI)
+ PHIToResolve.push_back(cast<PHINode>(OldI));
+ }
+
+ // Otherwise, remap the rest of the instructions normally.
+ for (; I != NewBB->end(); ++I)
+ RemapInstruction(I, ValueMap);
+ }
+
+ // Defer PHI resolution until rest of function is resolved, PHI resolution
+ // requires the CFG to be up-to-date.
+ for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
+ const PHINode *OPN = PHIToResolve[phino];
+ unsigned NumPreds = OPN->getNumIncomingValues();
+ const BasicBlock *OldBB = OPN->getParent();
+ BasicBlock *NewBB = cast<BasicBlock>(ValueMap[OldBB]);
+
+ // Map operands for blocks that are live and remove operands for blocks
+ // that are dead.
+ for (; phino != PHIToResolve.size() &&
+ PHIToResolve[phino]->getParent() == OldBB; ++phino) {
+ OPN = PHIToResolve[phino];
+ PHINode *PN = cast<PHINode>(ValueMap[OPN]);
+ for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
+ if (BasicBlock *MappedBlock =
+ cast_or_null<BasicBlock>(ValueMap[PN->getIncomingBlock(pred)])) {
+ Value *InVal = MapValue(PN->getIncomingValue(pred), ValueMap);
+ assert(InVal && "Unknown input value?");
+ PN->setIncomingValue(pred, InVal);
+ PN->setIncomingBlock(pred, MappedBlock);
+ } else {
+ PN->removeIncomingValue(pred, false);
+ --pred, --e; // Revisit the next entry.
+ }
+ }
+ }
+
+ // The loop above has removed PHI entries for those blocks that are dead
+ // and has updated others. However, if a block is live (i.e. copied over)
+ // but its terminator has been changed to not go to this block, then our
+ // phi nodes will have invalid entries. Update the PHI nodes in this
+ // case.
+ PHINode *PN = cast<PHINode>(NewBB->begin());
+ NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
+ if (NumPreds != PN->getNumIncomingValues()) {
+ assert(NumPreds < PN->getNumIncomingValues());
+ // Count how many times each predecessor comes to this block.
+ std::map<BasicBlock*, unsigned> PredCount;
+ for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
+ PI != E; ++PI)
+ --PredCount[*PI];
+
+ // Figure out how many entries to remove from each PHI.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ ++PredCount[PN->getIncomingBlock(i)];
+
+ // At this point, the excess predecessor entries are positive in the
+ // map. Loop over all of the PHIs and remove excess predecessor
+ // entries.
+ BasicBlock::iterator I = NewBB->begin();
+ for (; (PN = dyn_cast<PHINode>(I)); ++I) {
+ for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
+ E = PredCount.end(); PCI != E; ++PCI) {
+ BasicBlock *Pred = PCI->first;
+ for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
+ PN->removeIncomingValue(Pred, false);
+ }
+ }
+ }
+
+ // If the loops above have made these phi nodes have 0 or 1 operand,
+ // replace them with undef or the input value. We must do this for
+ // correctness, because 0-operand phis are not valid.
+ PN = cast<PHINode>(NewBB->begin());
+ if (PN->getNumIncomingValues() == 0) {
+ BasicBlock::iterator I = NewBB->begin();
+ BasicBlock::const_iterator OldI = OldBB->begin();
+ while ((PN = dyn_cast<PHINode>(I++))) {
+ Value *NV = UndefValue::get(PN->getType());
+ PN->replaceAllUsesWith(NV);
+ assert(ValueMap[OldI] == PN && "ValueMap mismatch");
+ ValueMap[OldI] = NV;
+ PN->eraseFromParent();
+ ++OldI;
+ }
+ }
+ // NOTE: We cannot eliminate single entry phi nodes here, because of
+ // ValueMap. Single entry phi nodes can have multiple ValueMap entries
+ // pointing at them. Thus, deleting one would require scanning the ValueMap
+ // to update any entries in it that would require that. This would be
+ // really slow.
+ }
+
+ // Now that the inlined function body has been fully constructed, go through
+ // and zap unconditional fall-through branches. This happen all the time when
+ // specializing code: code specialization turns conditional branches into
+ // uncond branches, and this code folds them.
+ Function::iterator I = cast<BasicBlock>(ValueMap[&OldFunc->getEntryBlock()]);
+ while (I != NewFunc->end()) {
+ BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
+ if (!BI || BI->isConditional()) { ++I; continue; }
+
+ // Note that we can't eliminate uncond branches if the destination has
+ // single-entry PHI nodes. Eliminating the single-entry phi nodes would
+ // require scanning the ValueMap to update any entries that point to the phi
+ // node.
+ BasicBlock *Dest = BI->getSuccessor(0);
+ if (!Dest->getSinglePredecessor() || isa<PHINode>(Dest->begin())) {
+ ++I; continue;
+ }
+
+ // We know all single-entry PHI nodes in the inlined function have been
+ // removed, so we just need to splice the blocks.
+ BI->eraseFromParent();
+
+ // Move all the instructions in the succ to the pred.
+ I->getInstList().splice(I->end(), Dest->getInstList());
+
+ // Make all PHI nodes that referred to Dest now refer to I as their source.
+ Dest->replaceAllUsesWith(I);
+
+ // Remove the dest block.
+ Dest->eraseFromParent();
+
+ // Do not increment I, iteratively merge all things this block branches to.
+ }
+}
diff --git a/lib/Transforms/Utils/CloneModule.cpp b/lib/Transforms/Utils/CloneModule.cpp
new file mode 100644
index 0000000..d64d58f
--- /dev/null
+++ b/lib/Transforms/Utils/CloneModule.cpp
@@ -0,0 +1,124 @@
+//===- CloneModule.cpp - Clone an entire module ---------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the CloneModule interface which makes a copy of an
+// entire module.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Module.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/TypeSymbolTable.h"
+#include "llvm/Constant.h"
+#include "ValueMapper.h"
+using namespace llvm;
+
+/// CloneModule - Return an exact copy of the specified module. This is not as
+/// easy as it might seem because we have to worry about making copies of global
+/// variables and functions, and making their (initializers and references,
+/// respectively) refer to the right globals.
+///
+Module *llvm::CloneModule(const Module *M) {
+ // Create the value map that maps things from the old module over to the new
+ // module.
+ DenseMap<const Value*, Value*> ValueMap;
+ return CloneModule(M, ValueMap);
+}
+
+Module *llvm::CloneModule(const Module *M,
+ DenseMap<const Value*, Value*> &ValueMap) {
+ // First off, we need to create the new module...
+ Module *New = new Module(M->getModuleIdentifier());
+ New->setDataLayout(M->getDataLayout());
+ New->setTargetTriple(M->getTargetTriple());
+ New->setModuleInlineAsm(M->getModuleInlineAsm());
+
+ // Copy all of the type symbol table entries over.
+ const TypeSymbolTable &TST = M->getTypeSymbolTable();
+ for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
+ TI != TE; ++TI)
+ New->addTypeName(TI->first, TI->second);
+
+ // Copy all of the dependent libraries over.
+ for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
+ New->addLibrary(*I);
+
+ // Loop over all of the global variables, making corresponding globals in the
+ // new module. Here we add them to the ValueMap and to the new Module. We
+ // don't worry about attributes or initializers, they will come later.
+ //
+ for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
+ I != E; ++I)
+ ValueMap[I] = new GlobalVariable(I->getType()->getElementType(), false,
+ GlobalValue::ExternalLinkage, 0,
+ I->getName(), New);
+
+ // Loop over the functions in the module, making external functions as before
+ for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
+ Function *NF =
+ new Function(cast<FunctionType>(I->getType()->getElementType()),
+ GlobalValue::ExternalLinkage, I->getName(), New);
+ NF->setCallingConv(I->getCallingConv());
+ ValueMap[I]= NF;
+ }
+
+ // Loop over the aliases in the module
+ for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
+ I != E; ++I)
+ ValueMap[I] = new GlobalAlias(I->getType(), GlobalAlias::ExternalLinkage,
+ I->getName(), NULL, New);
+
+ // Now that all of the things that global variable initializer can refer to
+ // have been created, loop through and copy the global variable referrers
+ // over... We also set the attributes on the global now.
+ //
+ for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
+ I != E; ++I) {
+ GlobalVariable *GV = cast<GlobalVariable>(ValueMap[I]);
+ if (I->hasInitializer())
+ GV->setInitializer(cast<Constant>(MapValue(I->getInitializer(),
+ ValueMap)));
+ GV->setLinkage(I->getLinkage());
+ GV->setThreadLocal(I->isThreadLocal());
+ GV->setConstant(I->isConstant());
+ }
+
+ // Similarly, copy over function bodies now...
+ //
+ for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
+ Function *F = cast<Function>(ValueMap[I]);
+ if (!I->isDeclaration()) {
+ Function::arg_iterator DestI = F->arg_begin();
+ for (Function::const_arg_iterator J = I->arg_begin(); J != I->arg_end();
+ ++J) {
+ DestI->setName(J->getName());
+ ValueMap[J] = DestI++;
+ }
+
+ std::vector<ReturnInst*> Returns; // Ignore returns cloned...
+ CloneFunctionInto(F, I, ValueMap, Returns);
+ }
+
+ F->setLinkage(I->getLinkage());
+ }
+
+ // And aliases
+ for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
+ I != E; ++I) {
+ GlobalAlias *GA = cast<GlobalAlias>(ValueMap[I]);
+ GA->setLinkage(I->getLinkage());
+ if (const Constant* C = I->getAliasee())
+ GA->setAliasee(cast<Constant>(MapValue(C, ValueMap)));
+ }
+
+ return New;
+}
+
+// vim: sw=2
diff --git a/lib/Transforms/Utils/CloneTrace.cpp b/lib/Transforms/Utils/CloneTrace.cpp
new file mode 100644
index 0000000..97e57b2
--- /dev/null
+++ b/lib/Transforms/Utils/CloneTrace.cpp
@@ -0,0 +1,120 @@
+//===- CloneTrace.cpp - Clone a trace -------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the CloneTrace interface, which is used when writing
+// runtime optimizations. It takes a vector of basic blocks clones the basic
+// blocks, removes internal phi nodes, adds it to the same function as the
+// original (although there is no jump to it) and returns the new vector of
+// basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/Trace.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "ValueMapper.h"
+using namespace llvm;
+
+//Clones the trace (a vector of basic blocks)
+std::vector<BasicBlock *>
+llvm::CloneTrace(const std::vector<BasicBlock*> &origTrace) {
+ std::vector<BasicBlock *> clonedTrace;
+ DenseMap<const Value*, Value*> ValueMap;
+
+ //First, loop over all the Basic Blocks in the trace and copy
+ //them using CloneBasicBlock. Also fix the phi nodes during
+ //this loop. To fix the phi nodes, we delete incoming branches
+ //that are not in the trace.
+ for(std::vector<BasicBlock *>::const_iterator T = origTrace.begin(),
+ End = origTrace.end(); T != End; ++T) {
+
+ //Clone Basic Block
+ BasicBlock *clonedBlock =
+ CloneBasicBlock(*T, ValueMap, ".tr", (*T)->getParent());
+
+ //Add it to our new trace
+ clonedTrace.push_back(clonedBlock);
+
+ //Add this new mapping to our Value Map
+ ValueMap[*T] = clonedBlock;
+
+ //Loop over the phi instructions and delete operands
+ //that are from blocks not in the trace
+ //only do this if we are NOT the first block
+ if(T != origTrace.begin()) {
+ for (BasicBlock::iterator I = clonedBlock->begin();
+ isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ //get incoming value for the previous BB
+ Value *V = PN->getIncomingValueForBlock(*(T-1));
+ assert(V && "No incoming value from a BasicBlock in our trace!");
+
+ //remap our phi node to point to incoming value
+ ValueMap[*&I] = V;
+
+ //remove phi node
+ clonedBlock->getInstList().erase(PN);
+ }
+ }
+ }
+
+ //Second loop to do the remapping
+ for(std::vector<BasicBlock *>::const_iterator BB = clonedTrace.begin(),
+ BE = clonedTrace.end(); BB != BE; ++BB) {
+ for(BasicBlock::iterator I = (*BB)->begin(); I != (*BB)->end(); ++I) {
+
+ //Loop over all the operands of the instruction
+ for(unsigned op=0, E = I->getNumOperands(); op != E; ++op) {
+ const Value *Op = I->getOperand(op);
+
+ //Get it out of the value map
+ Value *V = ValueMap[Op];
+
+ //If not in the value map, then its outside our trace so ignore
+ if(V != 0)
+ I->setOperand(op,V);
+ }
+ }
+ }
+
+ //return new vector of basic blocks
+ return clonedTrace;
+}
+
+/// CloneTraceInto - Clone T into NewFunc. Original<->clone mapping is
+/// saved in ValueMap.
+///
+void llvm::CloneTraceInto(Function *NewFunc, Trace &T,
+ DenseMap<const Value*, Value*> &ValueMap,
+ const char *NameSuffix) {
+ assert(NameSuffix && "NameSuffix cannot be null!");
+
+ // Loop over all of the basic blocks in the trace, cloning them as
+ // appropriate.
+ //
+ for (Trace::const_iterator BI = T.begin(), BE = T.end(); BI != BE; ++BI) {
+ const BasicBlock *BB = *BI;
+
+ // Create a new basic block and copy instructions into it!
+ BasicBlock *CBB = CloneBasicBlock(BB, ValueMap, NameSuffix, NewFunc);
+ ValueMap[BB] = CBB; // Add basic block mapping.
+ }
+
+ // Loop over all of the instructions in the new function, fixing up operand
+ // references as we go. This uses ValueMap to do all the hard work.
+ //
+ for (Function::iterator BB =
+ cast<BasicBlock>(ValueMap[T.getEntryBasicBlock()]),
+ BE = NewFunc->end(); BB != BE; ++BB)
+ // Loop over all instructions, fixing each one as we find it...
+ for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
+ RemapInstruction(II, ValueMap);
+}
+
diff --git a/lib/Transforms/Utils/CodeExtractor.cpp b/lib/Transforms/Utils/CodeExtractor.cpp
new file mode 100644
index 0000000..aaf9986
--- /dev/null
+++ b/lib/Transforms/Utils/CodeExtractor.cpp
@@ -0,0 +1,737 @@
+//===- CodeExtractor.cpp - Pull code region into a new function -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the interface to tear out a code region, such as an
+// individual loop or a parallel section, into a new function, replacing it with
+// a call to the new function.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/FunctionUtils.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/StringExtras.h"
+#include <algorithm>
+#include <set>
+using namespace llvm;
+
+// Provide a command-line option to aggregate function arguments into a struct
+// for functions produced by the code extrator. This is useful when converting
+// extracted functions to pthread-based code, as only one argument (void*) can
+// be passed in to pthread_create().
+static cl::opt<bool>
+AggregateArgsOpt("aggregate-extracted-args", cl::Hidden,
+ cl::desc("Aggregate arguments to code-extracted functions"));
+
+namespace {
+ class VISIBILITY_HIDDEN CodeExtractor {
+ typedef std::vector<Value*> Values;
+ std::set<BasicBlock*> BlocksToExtract;
+ DominatorTree* DT;
+ bool AggregateArgs;
+ unsigned NumExitBlocks;
+ const Type *RetTy;
+ public:
+ CodeExtractor(DominatorTree* dt = 0, bool AggArgs = false)
+ : DT(dt), AggregateArgs(AggArgs||AggregateArgsOpt), NumExitBlocks(~0U) {}
+
+ Function *ExtractCodeRegion(const std::vector<BasicBlock*> &code);
+
+ bool isEligible(const std::vector<BasicBlock*> &code);
+
+ private:
+ /// definedInRegion - Return true if the specified value is defined in the
+ /// extracted region.
+ bool definedInRegion(Value *V) const {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (BlocksToExtract.count(I->getParent()))
+ return true;
+ return false;
+ }
+
+ /// definedInCaller - Return true if the specified value is defined in the
+ /// function being code extracted, but not in the region being extracted.
+ /// These values must be passed in as live-ins to the function.
+ bool definedInCaller(Value *V) const {
+ if (isa<Argument>(V)) return true;
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (!BlocksToExtract.count(I->getParent()))
+ return true;
+ return false;
+ }
+
+ void severSplitPHINodes(BasicBlock *&Header);
+ void splitReturnBlocks();
+ void findInputsOutputs(Values &inputs, Values &outputs);
+
+ Function *constructFunction(const Values &inputs,
+ const Values &outputs,
+ BasicBlock *header,
+ BasicBlock *newRootNode, BasicBlock *newHeader,
+ Function *oldFunction, Module *M);
+
+ void moveCodeToFunction(Function *newFunction);
+
+ void emitCallAndSwitchStatement(Function *newFunction,
+ BasicBlock *newHeader,
+ Values &inputs,
+ Values &outputs);
+
+ };
+}
+
+/// severSplitPHINodes - If a PHI node has multiple inputs from outside of the
+/// region, we need to split the entry block of the region so that the PHI node
+/// is easier to deal with.
+void CodeExtractor::severSplitPHINodes(BasicBlock *&Header) {
+ bool HasPredsFromRegion = false;
+ unsigned NumPredsOutsideRegion = 0;
+
+ if (Header != &Header->getParent()->getEntryBlock()) {
+ PHINode *PN = dyn_cast<PHINode>(Header->begin());
+ if (!PN) return; // No PHI nodes.
+
+ // If the header node contains any PHI nodes, check to see if there is more
+ // than one entry from outside the region. If so, we need to sever the
+ // header block into two.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (BlocksToExtract.count(PN->getIncomingBlock(i)))
+ HasPredsFromRegion = true;
+ else
+ ++NumPredsOutsideRegion;
+
+ // If there is one (or fewer) predecessor from outside the region, we don't
+ // need to do anything special.
+ if (NumPredsOutsideRegion <= 1) return;
+ }
+
+ // Otherwise, we need to split the header block into two pieces: one
+ // containing PHI nodes merging values from outside of the region, and a
+ // second that contains all of the code for the block and merges back any
+ // incoming values from inside of the region.
+ BasicBlock::iterator AfterPHIs = Header->begin();
+ while (isa<PHINode>(AfterPHIs)) ++AfterPHIs;
+ BasicBlock *NewBB = Header->splitBasicBlock(AfterPHIs,
+ Header->getName()+".ce");
+
+ // We only want to code extract the second block now, and it becomes the new
+ // header of the region.
+ BasicBlock *OldPred = Header;
+ BlocksToExtract.erase(OldPred);
+ BlocksToExtract.insert(NewBB);
+ Header = NewBB;
+
+ // Okay, update dominator sets. The blocks that dominate the new one are the
+ // blocks that dominate TIBB plus the new block itself.
+ if (DT)
+ DT->splitBlock(NewBB);
+
+ // Okay, now we need to adjust the PHI nodes and any branches from within the
+ // region to go to the new header block instead of the old header block.
+ if (HasPredsFromRegion) {
+ PHINode *PN = cast<PHINode>(OldPred->begin());
+ // Loop over all of the predecessors of OldPred that are in the region,
+ // changing them to branch to NewBB instead.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (BlocksToExtract.count(PN->getIncomingBlock(i))) {
+ TerminatorInst *TI = PN->getIncomingBlock(i)->getTerminator();
+ TI->replaceUsesOfWith(OldPred, NewBB);
+ }
+
+ // Okay, everthing within the region is now branching to the right block, we
+ // just have to update the PHI nodes now, inserting PHI nodes into NewBB.
+ for (AfterPHIs = OldPred->begin(); isa<PHINode>(AfterPHIs); ++AfterPHIs) {
+ PHINode *PN = cast<PHINode>(AfterPHIs);
+ // Create a new PHI node in the new region, which has an incoming value
+ // from OldPred of PN.
+ PHINode *NewPN = new PHINode(PN->getType(), PN->getName()+".ce",
+ NewBB->begin());
+ NewPN->addIncoming(PN, OldPred);
+
+ // Loop over all of the incoming value in PN, moving them to NewPN if they
+ // are from the extracted region.
+ for (unsigned i = 0; i != PN->getNumIncomingValues(); ++i) {
+ if (BlocksToExtract.count(PN->getIncomingBlock(i))) {
+ NewPN->addIncoming(PN->getIncomingValue(i), PN->getIncomingBlock(i));
+ PN->removeIncomingValue(i);
+ --i;
+ }
+ }
+ }
+ }
+}
+
+void CodeExtractor::splitReturnBlocks() {
+ for (std::set<BasicBlock*>::iterator I = BlocksToExtract.begin(),
+ E = BlocksToExtract.end(); I != E; ++I)
+ if (ReturnInst *RI = dyn_cast<ReturnInst>((*I)->getTerminator()))
+ (*I)->splitBasicBlock(RI, (*I)->getName()+".ret");
+}
+
+// findInputsOutputs - Find inputs to, outputs from the code region.
+//
+void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs) {
+ std::set<BasicBlock*> ExitBlocks;
+ for (std::set<BasicBlock*>::const_iterator ci = BlocksToExtract.begin(),
+ ce = BlocksToExtract.end(); ci != ce; ++ci) {
+ BasicBlock *BB = *ci;
+
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ // If a used value is defined outside the region, it's an input. If an
+ // instruction is used outside the region, it's an output.
+ for (User::op_iterator O = I->op_begin(), E = I->op_end(); O != E; ++O)
+ if (definedInCaller(*O))
+ inputs.push_back(*O);
+
+ // Consider uses of this instruction (outputs).
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ UI != E; ++UI)
+ if (!definedInRegion(*UI)) {
+ outputs.push_back(I);
+ break;
+ }
+ } // for: insts
+
+ // Keep track of the exit blocks from the region.
+ TerminatorInst *TI = BB->getTerminator();
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ if (!BlocksToExtract.count(TI->getSuccessor(i)))
+ ExitBlocks.insert(TI->getSuccessor(i));
+ } // for: basic blocks
+
+ NumExitBlocks = ExitBlocks.size();
+
+ // Eliminate duplicates.
+ std::sort(inputs.begin(), inputs.end());
+ inputs.erase(std::unique(inputs.begin(), inputs.end()), inputs.end());
+ std::sort(outputs.begin(), outputs.end());
+ outputs.erase(std::unique(outputs.begin(), outputs.end()), outputs.end());
+}
+
+/// constructFunction - make a function based on inputs and outputs, as follows:
+/// f(in0, ..., inN, out0, ..., outN)
+///
+Function *CodeExtractor::constructFunction(const Values &inputs,
+ const Values &outputs,
+ BasicBlock *header,
+ BasicBlock *newRootNode,
+ BasicBlock *newHeader,
+ Function *oldFunction,
+ Module *M) {
+ DOUT << "inputs: " << inputs.size() << "\n";
+ DOUT << "outputs: " << outputs.size() << "\n";
+
+ // This function returns unsigned, outputs will go back by reference.
+ switch (NumExitBlocks) {
+ case 0:
+ case 1: RetTy = Type::VoidTy; break;
+ case 2: RetTy = Type::Int1Ty; break;
+ default: RetTy = Type::Int16Ty; break;
+ }
+
+ std::vector<const Type*> paramTy;
+
+ // Add the types of the input values to the function's argument list
+ for (Values::const_iterator i = inputs.begin(),
+ e = inputs.end(); i != e; ++i) {
+ const Value *value = *i;
+ DOUT << "value used in func: " << *value << "\n";
+ paramTy.push_back(value->getType());
+ }
+
+ // Add the types of the output values to the function's argument list.
+ for (Values::const_iterator I = outputs.begin(), E = outputs.end();
+ I != E; ++I) {
+ DOUT << "instr used in func: " << **I << "\n";
+ if (AggregateArgs)
+ paramTy.push_back((*I)->getType());
+ else
+ paramTy.push_back(PointerType::get((*I)->getType()));
+ }
+
+ DOUT << "Function type: " << *RetTy << " f(";
+ for (std::vector<const Type*>::iterator i = paramTy.begin(),
+ e = paramTy.end(); i != e; ++i)
+ DOUT << **i << ", ";
+ DOUT << ")\n";
+
+ if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
+ PointerType *StructPtr = PointerType::get(StructType::get(paramTy));
+ paramTy.clear();
+ paramTy.push_back(StructPtr);
+ }
+ const FunctionType *funcType = FunctionType::get(RetTy, paramTy, false);
+
+ // Create the new function
+ Function *newFunction = new Function(funcType,
+ GlobalValue::InternalLinkage,
+ oldFunction->getName() + "_" +
+ header->getName(), M);
+ newFunction->getBasicBlockList().push_back(newRootNode);
+
+ // Create an iterator to name all of the arguments we inserted.
+ Function::arg_iterator AI = newFunction->arg_begin();
+
+ // Rewrite all users of the inputs in the extracted region to use the
+ // arguments (or appropriate addressing into struct) instead.
+ for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
+ Value *RewriteVal;
+ if (AggregateArgs) {
+ Value *Idx0 = Constant::getNullValue(Type::Int32Ty);
+ Value *Idx1 = ConstantInt::get(Type::Int32Ty, i);
+ std::string GEPname = "gep_" + inputs[i]->getName();
+ TerminatorInst *TI = newFunction->begin()->getTerminator();
+ GetElementPtrInst *GEP = new GetElementPtrInst(AI, Idx0, Idx1,
+ GEPname, TI);
+ RewriteVal = new LoadInst(GEP, "load" + GEPname, TI);
+ } else
+ RewriteVal = AI++;
+
+ std::vector<User*> Users(inputs[i]->use_begin(), inputs[i]->use_end());
+ for (std::vector<User*>::iterator use = Users.begin(), useE = Users.end();
+ use != useE; ++use)
+ if (Instruction* inst = dyn_cast<Instruction>(*use))
+ if (BlocksToExtract.count(inst->getParent()))
+ inst->replaceUsesOfWith(inputs[i], RewriteVal);
+ }
+
+ // Set names for input and output arguments.
+ if (!AggregateArgs) {
+ AI = newFunction->arg_begin();
+ for (unsigned i = 0, e = inputs.size(); i != e; ++i, ++AI)
+ AI->setName(inputs[i]->getName());
+ for (unsigned i = 0, e = outputs.size(); i != e; ++i, ++AI)
+ AI->setName(outputs[i]->getName()+".out");
+ }
+
+ // Rewrite branches to basic blocks outside of the loop to new dummy blocks
+ // within the new function. This must be done before we lose track of which
+ // blocks were originally in the code region.
+ std::vector<User*> Users(header->use_begin(), header->use_end());
+ for (unsigned i = 0, e = Users.size(); i != e; ++i)
+ // The BasicBlock which contains the branch is not in the region
+ // modify the branch target to a new block
+ if (TerminatorInst *TI = dyn_cast<TerminatorInst>(Users[i]))
+ if (!BlocksToExtract.count(TI->getParent()) &&
+ TI->getParent()->getParent() == oldFunction)
+ TI->replaceUsesOfWith(header, newHeader);
+
+ return newFunction;
+}
+
+/// emitCallAndSwitchStatement - This method sets up the caller side by adding
+/// the call instruction, splitting any PHI nodes in the header block as
+/// necessary.
+void CodeExtractor::
+emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
+ Values &inputs, Values &outputs) {
+ // Emit a call to the new function, passing in: *pointer to struct (if
+ // aggregating parameters), or plan inputs and allocated memory for outputs
+ std::vector<Value*> params, StructValues, ReloadOutputs;
+
+ // Add inputs as params, or to be filled into the struct
+ for (Values::iterator i = inputs.begin(), e = inputs.end(); i != e; ++i)
+ if (AggregateArgs)
+ StructValues.push_back(*i);
+ else
+ params.push_back(*i);
+
+ // Create allocas for the outputs
+ for (Values::iterator i = outputs.begin(), e = outputs.end(); i != e; ++i) {
+ if (AggregateArgs) {
+ StructValues.push_back(*i);
+ } else {
+ AllocaInst *alloca =
+ new AllocaInst((*i)->getType(), 0, (*i)->getName()+".loc",
+ codeReplacer->getParent()->begin()->begin());
+ ReloadOutputs.push_back(alloca);
+ params.push_back(alloca);
+ }
+ }
+
+ AllocaInst *Struct = 0;
+ if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
+ std::vector<const Type*> ArgTypes;
+ for (Values::iterator v = StructValues.begin(),
+ ve = StructValues.end(); v != ve; ++v)
+ ArgTypes.push_back((*v)->getType());
+
+ // Allocate a struct at the beginning of this function
+ Type *StructArgTy = StructType::get(ArgTypes);
+ Struct =
+ new AllocaInst(StructArgTy, 0, "structArg",
+ codeReplacer->getParent()->begin()->begin());
+ params.push_back(Struct);
+
+ for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
+ Value *Idx0 = Constant::getNullValue(Type::Int32Ty);
+ Value *Idx1 = ConstantInt::get(Type::Int32Ty, i);
+ GetElementPtrInst *GEP =
+ new GetElementPtrInst(Struct, Idx0, Idx1,
+ "gep_" + StructValues[i]->getName());
+ codeReplacer->getInstList().push_back(GEP);
+ StoreInst *SI = new StoreInst(StructValues[i], GEP);
+ codeReplacer->getInstList().push_back(SI);
+ }
+ }
+
+ // Emit the call to the function
+ CallInst *call = new CallInst(newFunction, ¶ms[0], params.size(),
+ NumExitBlocks > 1 ? "targetBlock" : "");
+ codeReplacer->getInstList().push_back(call);
+
+ Function::arg_iterator OutputArgBegin = newFunction->arg_begin();
+ unsigned FirstOut = inputs.size();
+ if (!AggregateArgs)
+ std::advance(OutputArgBegin, inputs.size());
+
+ // Reload the outputs passed in by reference
+ for (unsigned i = 0, e = outputs.size(); i != e; ++i) {
+ Value *Output = 0;
+ if (AggregateArgs) {
+ Value *Idx0 = Constant::getNullValue(Type::Int32Ty);
+ Value *Idx1 = ConstantInt::get(Type::Int32Ty, FirstOut + i);
+ GetElementPtrInst *GEP
+ = new GetElementPtrInst(Struct, Idx0, Idx1,
+ "gep_reload_" + outputs[i]->getName());
+ codeReplacer->getInstList().push_back(GEP);
+ Output = GEP;
+ } else {
+ Output = ReloadOutputs[i];
+ }
+ LoadInst *load = new LoadInst(Output, outputs[i]->getName()+".reload");
+ codeReplacer->getInstList().push_back(load);
+ std::vector<User*> Users(outputs[i]->use_begin(), outputs[i]->use_end());
+ for (unsigned u = 0, e = Users.size(); u != e; ++u) {
+ Instruction *inst = cast<Instruction>(Users[u]);
+ if (!BlocksToExtract.count(inst->getParent()))
+ inst->replaceUsesOfWith(outputs[i], load);
+ }
+ }
+
+ // Now we can emit a switch statement using the call as a value.
+ SwitchInst *TheSwitch =
+ new SwitchInst(ConstantInt::getNullValue(Type::Int16Ty),
+ codeReplacer, 0, codeReplacer);
+
+ // Since there may be multiple exits from the original region, make the new
+ // function return an unsigned, switch on that number. This loop iterates
+ // over all of the blocks in the extracted region, updating any terminator
+ // instructions in the to-be-extracted region that branch to blocks that are
+ // not in the region to be extracted.
+ std::map<BasicBlock*, BasicBlock*> ExitBlockMap;
+
+ unsigned switchVal = 0;
+ for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
+ e = BlocksToExtract.end(); i != e; ++i) {
+ TerminatorInst *TI = (*i)->getTerminator();
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ if (!BlocksToExtract.count(TI->getSuccessor(i))) {
+ BasicBlock *OldTarget = TI->getSuccessor(i);
+ // add a new basic block which returns the appropriate value
+ BasicBlock *&NewTarget = ExitBlockMap[OldTarget];
+ if (!NewTarget) {
+ // If we don't already have an exit stub for this non-extracted
+ // destination, create one now!
+ NewTarget = new BasicBlock(OldTarget->getName() + ".exitStub",
+ newFunction);
+ unsigned SuccNum = switchVal++;
+
+ Value *brVal = 0;
+ switch (NumExitBlocks) {
+ case 0:
+ case 1: break; // No value needed.
+ case 2: // Conditional branch, return a bool
+ brVal = ConstantInt::get(Type::Int1Ty, !SuccNum);
+ break;
+ default:
+ brVal = ConstantInt::get(Type::Int16Ty, SuccNum);
+ break;
+ }
+
+ ReturnInst *NTRet = new ReturnInst(brVal, NewTarget);
+
+ // Update the switch instruction.
+ TheSwitch->addCase(ConstantInt::get(Type::Int16Ty, SuccNum),
+ OldTarget);
+
+ // Restore values just before we exit
+ Function::arg_iterator OAI = OutputArgBegin;
+ for (unsigned out = 0, e = outputs.size(); out != e; ++out) {
+ // For an invoke, the normal destination is the only one that is
+ // dominated by the result of the invocation
+ BasicBlock *DefBlock = cast<Instruction>(outputs[out])->getParent();
+
+ bool DominatesDef = true;
+
+ if (InvokeInst *Invoke = dyn_cast<InvokeInst>(outputs[out])) {
+ DefBlock = Invoke->getNormalDest();
+
+ // Make sure we are looking at the original successor block, not
+ // at a newly inserted exit block, which won't be in the dominator
+ // info.
+ for (std::map<BasicBlock*, BasicBlock*>::iterator I =
+ ExitBlockMap.begin(), E = ExitBlockMap.end(); I != E; ++I)
+ if (DefBlock == I->second) {
+ DefBlock = I->first;
+ break;
+ }
+
+ // In the extract block case, if the block we are extracting ends
+ // with an invoke instruction, make sure that we don't emit a
+ // store of the invoke value for the unwind block.
+ if (!DT && DefBlock != OldTarget)
+ DominatesDef = false;
+ }
+
+ if (DT)
+ DominatesDef = DT->dominates(DefBlock, OldTarget);
+
+ if (DominatesDef) {
+ if (AggregateArgs) {
+ Value *Idx0 = Constant::getNullValue(Type::Int32Ty);
+ Value *Idx1 = ConstantInt::get(Type::Int32Ty,FirstOut+out);
+ GetElementPtrInst *GEP =
+ new GetElementPtrInst(OAI, Idx0, Idx1,
+ "gep_" + outputs[out]->getName(),
+ NTRet);
+ new StoreInst(outputs[out], GEP, NTRet);
+ } else {
+ new StoreInst(outputs[out], OAI, NTRet);
+ }
+ }
+ // Advance output iterator even if we don't emit a store
+ if (!AggregateArgs) ++OAI;
+ }
+ }
+
+ // rewrite the original branch instruction with this new target
+ TI->setSuccessor(i, NewTarget);
+ }
+ }
+
+ // Now that we've done the deed, simplify the switch instruction.
+ const Type *OldFnRetTy = TheSwitch->getParent()->getParent()->getReturnType();
+ switch (NumExitBlocks) {
+ case 0:
+ // There are no successors (the block containing the switch itself), which
+ // means that previously this was the last part of the function, and hence
+ // this should be rewritten as a `ret'
+
+ // Check if the function should return a value
+ if (OldFnRetTy == Type::VoidTy) {
+ new ReturnInst(0, TheSwitch); // Return void
+ } else if (OldFnRetTy == TheSwitch->getCondition()->getType()) {
+ // return what we have
+ new ReturnInst(TheSwitch->getCondition(), TheSwitch);
+ } else {
+ // Otherwise we must have code extracted an unwind or something, just
+ // return whatever we want.
+ new ReturnInst(Constant::getNullValue(OldFnRetTy), TheSwitch);
+ }
+
+ TheSwitch->getParent()->getInstList().erase(TheSwitch);
+ break;
+ case 1:
+ // Only a single destination, change the switch into an unconditional
+ // branch.
+ new BranchInst(TheSwitch->getSuccessor(1), TheSwitch);
+ TheSwitch->getParent()->getInstList().erase(TheSwitch);
+ break;
+ case 2:
+ new BranchInst(TheSwitch->getSuccessor(1), TheSwitch->getSuccessor(2),
+ call, TheSwitch);
+ TheSwitch->getParent()->getInstList().erase(TheSwitch);
+ break;
+ default:
+ // Otherwise, make the default destination of the switch instruction be one
+ // of the other successors.
+ TheSwitch->setOperand(0, call);
+ TheSwitch->setSuccessor(0, TheSwitch->getSuccessor(NumExitBlocks));
+ TheSwitch->removeCase(NumExitBlocks); // Remove redundant case
+ break;
+ }
+}
+
+void CodeExtractor::moveCodeToFunction(Function *newFunction) {
+ Function *oldFunc = (*BlocksToExtract.begin())->getParent();
+ Function::BasicBlockListType &oldBlocks = oldFunc->getBasicBlockList();
+ Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
+
+ for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
+ e = BlocksToExtract.end(); i != e; ++i) {
+ // Delete the basic block from the old function, and the list of blocks
+ oldBlocks.remove(*i);
+
+ // Insert this basic block into the new function
+ newBlocks.push_back(*i);
+ }
+}
+
+/// ExtractRegion - Removes a loop from a function, replaces it with a call to
+/// new function. Returns pointer to the new function.
+///
+/// algorithm:
+///
+/// find inputs and outputs for the region
+///
+/// for inputs: add to function as args, map input instr* to arg#
+/// for outputs: add allocas for scalars,
+/// add to func as args, map output instr* to arg#
+///
+/// rewrite func to use argument #s instead of instr*
+///
+/// for each scalar output in the function: at every exit, store intermediate
+/// computed result back into memory.
+///
+Function *CodeExtractor::
+ExtractCodeRegion(const std::vector<BasicBlock*> &code) {
+ if (!isEligible(code))
+ return 0;
+
+ // 1) Find inputs, outputs
+ // 2) Construct new function
+ // * Add allocas for defs, pass as args by reference
+ // * Pass in uses as args
+ // 3) Move code region, add call instr to func
+ //
+ BlocksToExtract.insert(code.begin(), code.end());
+
+ Values inputs, outputs;
+
+ // Assumption: this is a single-entry code region, and the header is the first
+ // block in the region.
+ BasicBlock *header = code[0];
+
+ for (unsigned i = 1, e = code.size(); i != e; ++i)
+ for (pred_iterator PI = pred_begin(code[i]), E = pred_end(code[i]);
+ PI != E; ++PI)
+ assert(BlocksToExtract.count(*PI) &&
+ "No blocks in this region may have entries from outside the region"
+ " except for the first block!");
+
+ // If we have to split PHI nodes or the entry block, do so now.
+ severSplitPHINodes(header);
+
+ // If we have any return instructions in the region, split those blocks so
+ // that the return is not in the region.
+ splitReturnBlocks();
+
+ Function *oldFunction = header->getParent();
+
+ // This takes place of the original loop
+ BasicBlock *codeReplacer = new BasicBlock("codeRepl", oldFunction, header);
+
+ // The new function needs a root node because other nodes can branch to the
+ // head of the region, but the entry node of a function cannot have preds.
+ BasicBlock *newFuncRoot = new BasicBlock("newFuncRoot");
+ newFuncRoot->getInstList().push_back(new BranchInst(header));
+
+ // Find inputs to, outputs from the code region.
+ findInputsOutputs(inputs, outputs);
+
+ // Construct new function based on inputs/outputs & add allocas for all defs.
+ Function *newFunction = constructFunction(inputs, outputs, header,
+ newFuncRoot,
+ codeReplacer, oldFunction,
+ oldFunction->getParent());
+
+ emitCallAndSwitchStatement(newFunction, codeReplacer, inputs, outputs);
+
+ moveCodeToFunction(newFunction);
+
+ // Loop over all of the PHI nodes in the header block, and change any
+ // references to the old incoming edge to be the new incoming edge.
+ for (BasicBlock::iterator I = header->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (!BlocksToExtract.count(PN->getIncomingBlock(i)))
+ PN->setIncomingBlock(i, newFuncRoot);
+ }
+
+ // Look at all successors of the codeReplacer block. If any of these blocks
+ // had PHI nodes in them, we need to update the "from" block to be the code
+ // replacer, not the original block in the extracted region.
+ std::vector<BasicBlock*> Succs(succ_begin(codeReplacer),
+ succ_end(codeReplacer));
+ for (unsigned i = 0, e = Succs.size(); i != e; ++i)
+ for (BasicBlock::iterator I = Succs[i]->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ std::set<BasicBlock*> ProcessedPreds;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (BlocksToExtract.count(PN->getIncomingBlock(i)))
+ if (ProcessedPreds.insert(PN->getIncomingBlock(i)).second)
+ PN->setIncomingBlock(i, codeReplacer);
+ else {
+ // There were multiple entries in the PHI for this block, now there
+ // is only one, so remove the duplicated entries.
+ PN->removeIncomingValue(i, false);
+ --i; --e;
+ }
+ }
+
+ //cerr << "NEW FUNCTION: " << *newFunction;
+ // verifyFunction(*newFunction);
+
+ // cerr << "OLD FUNCTION: " << *oldFunction;
+ // verifyFunction(*oldFunction);
+
+ DEBUG(if (verifyFunction(*newFunction)) abort());
+ return newFunction;
+}
+
+bool CodeExtractor::isEligible(const std::vector<BasicBlock*> &code) {
+ // Deny code region if it contains allocas or vastarts.
+ for (std::vector<BasicBlock*>::const_iterator BB = code.begin(), e=code.end();
+ BB != e; ++BB)
+ for (BasicBlock::const_iterator I = (*BB)->begin(), Ie = (*BB)->end();
+ I != Ie; ++I)
+ if (isa<AllocaInst>(*I))
+ return false;
+ else if (const CallInst *CI = dyn_cast<CallInst>(I))
+ if (const Function *F = CI->getCalledFunction())
+ if (F->getIntrinsicID() == Intrinsic::vastart)
+ return false;
+ return true;
+}
+
+
+/// ExtractCodeRegion - slurp a sequence of basic blocks into a brand new
+/// function
+///
+Function* llvm::ExtractCodeRegion(DominatorTree &DT,
+ const std::vector<BasicBlock*> &code,
+ bool AggregateArgs) {
+ return CodeExtractor(&DT, AggregateArgs).ExtractCodeRegion(code);
+}
+
+/// ExtractBasicBlock - slurp a natural loop into a brand new function
+///
+Function* llvm::ExtractLoop(DominatorTree &DT, Loop *L, bool AggregateArgs) {
+ return CodeExtractor(&DT, AggregateArgs).ExtractCodeRegion(L->getBlocks());
+}
+
+/// ExtractBasicBlock - slurp a basic block into a brand new function
+///
+Function* llvm::ExtractBasicBlock(BasicBlock *BB, bool AggregateArgs) {
+ std::vector<BasicBlock*> Blocks;
+ Blocks.push_back(BB);
+ return CodeExtractor(0, AggregateArgs).ExtractCodeRegion(Blocks);
+}
diff --git a/lib/Transforms/Utils/DemoteRegToStack.cpp b/lib/Transforms/Utils/DemoteRegToStack.cpp
new file mode 100644
index 0000000..df332b2
--- /dev/null
+++ b/lib/Transforms/Utils/DemoteRegToStack.cpp
@@ -0,0 +1,133 @@
+//===- DemoteRegToStack.cpp - Move a virtual register to the stack --------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provide the function DemoteRegToStack(). This function takes a
+// virtual register computed by an Instruction and replaces it with a slot in
+// the stack frame, allocated via alloca. It returns the pointer to the
+// AllocaInst inserted. After this function is called on an instruction, we are
+// guaranteed that the only user of the instruction is a store that is
+// immediately after it.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include <map>
+using namespace llvm;
+
+/// DemoteRegToStack - This function takes a virtual register computed by an
+/// Instruction and replaces it with a slot in the stack frame, allocated via
+/// alloca. This allows the CFG to be changed around without fear of
+/// invalidating the SSA information for the value. It returns the pointer to
+/// the alloca inserted to create a stack slot for I.
+///
+AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads) {
+ if (I.use_empty()) return 0; // nothing to do!
+
+ // Create a stack slot to hold the value.
+ Function *F = I.getParent()->getParent();
+ AllocaInst *Slot = new AllocaInst(I.getType(), 0, I.getName(),
+ F->getEntryBlock().begin());
+
+ // Change all of the users of the instruction to read from the stack slot
+ // instead.
+ while (!I.use_empty()) {
+ Instruction *U = cast<Instruction>(I.use_back());
+ if (PHINode *PN = dyn_cast<PHINode>(U)) {
+ // If this is a PHI node, we can't insert a load of the value before the
+ // use. Instead, insert the load in the predecessor block corresponding
+ // to the incoming value.
+ //
+ // Note that if there are multiple edges from a basic block to this PHI
+ // node that we cannot multiple loads. The problem is that the resultant
+ // PHI node will have multiple values (from each load) coming in from the
+ // same block, which is illegal SSA form. For this reason, we keep track
+ // and reuse loads we insert.
+ std::map<BasicBlock*, Value*> Loads;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (PN->getIncomingValue(i) == &I) {
+ Value *&V = Loads[PN->getIncomingBlock(i)];
+ if (V == 0) {
+ // Insert the load into the predecessor block
+ V = new LoadInst(Slot, I.getName()+".reload", VolatileLoads,
+ PN->getIncomingBlock(i)->getTerminator());
+ }
+ PN->setIncomingValue(i, V);
+ }
+
+ } else {
+ // If this is a normal instruction, just insert a load.
+ Value *V = new LoadInst(Slot, I.getName()+".reload", VolatileLoads, U);
+ U->replaceUsesOfWith(&I, V);
+ }
+ }
+
+
+ // Insert stores of the computed value into the stack slot. We have to be
+ // careful is I is an invoke instruction though, because we can't insert the
+ // store AFTER the terminator instruction.
+ BasicBlock::iterator InsertPt;
+ if (!isa<TerminatorInst>(I)) {
+ InsertPt = &I;
+ ++InsertPt;
+ } else {
+ // We cannot demote invoke instructions to the stack if their normal edge
+ // is critical.
+ InvokeInst &II = cast<InvokeInst>(I);
+ assert(II.getNormalDest()->getSinglePredecessor() &&
+ "Cannot demote invoke with a critical successor!");
+ InsertPt = II.getNormalDest()->begin();
+ }
+
+ for (; isa<PHINode>(InsertPt); ++InsertPt)
+ /* empty */; // Don't insert before any PHI nodes.
+ new StoreInst(&I, Slot, InsertPt);
+
+ return Slot;
+}
+
+
+/// DemotePHIToStack - This function takes a virtual register computed by a phi
+/// node and replaces it with a slot in the stack frame, allocated via alloca.
+/// The phi node is deleted and it returns the pointer to the alloca inserted.
+AllocaInst* llvm::DemotePHIToStack(PHINode *P) {
+ if (P->use_empty()) {
+ P->eraseFromParent();
+ return 0;
+ }
+
+ // Create a stack slot to hold the value.
+ Function *F = P->getParent()->getParent();
+ AllocaInst *Slot = new AllocaInst(P->getType(), 0, P->getName(),
+ F->getEntryBlock().begin());
+
+ // Iterate over each operand, insert store in each predecessor.
+ for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
+ if (InvokeInst *II = dyn_cast<InvokeInst>(P->getIncomingValue(i))) {
+ assert(II->getParent() != P->getIncomingBlock(i) &&
+ "Invoke edge not supported yet");
+ }
+ new StoreInst(P->getIncomingValue(i), Slot,
+ P->getIncomingBlock(i)->getTerminator());
+ }
+
+ // Insert load in place of the phi and replace all uses.
+ BasicBlock::iterator InsertPt;
+ for (InsertPt = P->getParent()->getInstList().begin();
+ isa<PHINode>(InsertPt); ++InsertPt);
+ Value *V = new LoadInst(Slot, P->getName()+".reload", P);
+ P->replaceAllUsesWith(V);
+
+ // Delete phi.
+ P->eraseFromParent();
+
+ return Slot;
+}
diff --git a/lib/Transforms/Utils/InlineFunction.cpp b/lib/Transforms/Utils/InlineFunction.cpp
new file mode 100644
index 0000000..9735a2f
--- /dev/null
+++ b/lib/Transforms/Utils/InlineFunction.cpp
@@ -0,0 +1,496 @@
+//===- InlineFunction.cpp - Code to perform function inlining -------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements inlining of a function into a call site, resolving
+// parameters and the return value as appropriate.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/CallSite.h"
+using namespace llvm;
+
+bool llvm::InlineFunction(CallInst *CI, CallGraph *CG, const TargetData *TD) {
+ return InlineFunction(CallSite(CI), CG, TD);
+}
+bool llvm::InlineFunction(InvokeInst *II, CallGraph *CG, const TargetData *TD) {
+ return InlineFunction(CallSite(II), CG, TD);
+}
+
+/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
+/// in the body of the inlined function into invokes and turn unwind
+/// instructions into branches to the invoke unwind dest.
+///
+/// II is the invoke instruction begin inlined. FirstNewBlock is the first
+/// block of the inlined code (the last block is the end of the function),
+/// and InlineCodeInfo is information about the code that got inlined.
+static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
+ ClonedCodeInfo &InlinedCodeInfo) {
+ BasicBlock *InvokeDest = II->getUnwindDest();
+ std::vector<Value*> InvokeDestPHIValues;
+
+ // If there are PHI nodes in the unwind destination block, we need to
+ // keep track of which values came into them from this invoke, then remove
+ // the entry for this block.
+ BasicBlock *InvokeBlock = II->getParent();
+ for (BasicBlock::iterator I = InvokeDest->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ // Save the value to use for this edge.
+ InvokeDestPHIValues.push_back(PN->getIncomingValueForBlock(InvokeBlock));
+ }
+
+ Function *Caller = FirstNewBlock->getParent();
+
+ // The inlined code is currently at the end of the function, scan from the
+ // start of the inlined code to its end, checking for stuff we need to
+ // rewrite.
+ if (InlinedCodeInfo.ContainsCalls || InlinedCodeInfo.ContainsUnwinds) {
+ for (Function::iterator BB = FirstNewBlock, E = Caller->end();
+ BB != E; ++BB) {
+ if (InlinedCodeInfo.ContainsCalls) {
+ for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ){
+ Instruction *I = BBI++;
+
+ // We only need to check for function calls: inlined invoke
+ // instructions require no special handling.
+ if (!isa<CallInst>(I)) continue;
+ CallInst *CI = cast<CallInst>(I);
+
+ // If this is an intrinsic function call or an inline asm, don't
+ // convert it to an invoke.
+ if ((CI->getCalledFunction() &&
+ CI->getCalledFunction()->getIntrinsicID()) ||
+ isa<InlineAsm>(CI->getCalledValue()))
+ continue;
+
+ // Convert this function call into an invoke instruction.
+ // First, split the basic block.
+ BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
+
+ // Next, create the new invoke instruction, inserting it at the end
+ // of the old basic block.
+ SmallVector<Value*, 8> InvokeArgs(CI->op_begin()+1, CI->op_end());
+ InvokeInst *II =
+ new InvokeInst(CI->getCalledValue(), Split, InvokeDest,
+ &InvokeArgs[0], InvokeArgs.size(),
+ CI->getName(), BB->getTerminator());
+ II->setCallingConv(CI->getCallingConv());
+
+ // Make sure that anything using the call now uses the invoke!
+ CI->replaceAllUsesWith(II);
+
+ // Delete the unconditional branch inserted by splitBasicBlock
+ BB->getInstList().pop_back();
+ Split->getInstList().pop_front(); // Delete the original call
+
+ // Update any PHI nodes in the exceptional block to indicate that
+ // there is now a new entry in them.
+ unsigned i = 0;
+ for (BasicBlock::iterator I = InvokeDest->begin();
+ isa<PHINode>(I); ++I, ++i) {
+ PHINode *PN = cast<PHINode>(I);
+ PN->addIncoming(InvokeDestPHIValues[i], BB);
+ }
+
+ // This basic block is now complete, start scanning the next one.
+ break;
+ }
+ }
+
+ if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
+ // An UnwindInst requires special handling when it gets inlined into an
+ // invoke site. Once this happens, we know that the unwind would cause
+ // a control transfer to the invoke exception destination, so we can
+ // transform it into a direct branch to the exception destination.
+ new BranchInst(InvokeDest, UI);
+
+ // Delete the unwind instruction!
+ UI->getParent()->getInstList().pop_back();
+
+ // Update any PHI nodes in the exceptional block to indicate that
+ // there is now a new entry in them.
+ unsigned i = 0;
+ for (BasicBlock::iterator I = InvokeDest->begin();
+ isa<PHINode>(I); ++I, ++i) {
+ PHINode *PN = cast<PHINode>(I);
+ PN->addIncoming(InvokeDestPHIValues[i], BB);
+ }
+ }
+ }
+ }
+
+ // Now that everything is happy, we have one final detail. The PHI nodes in
+ // the exception destination block still have entries due to the original
+ // invoke instruction. Eliminate these entries (which might even delete the
+ // PHI node) now.
+ InvokeDest->removePredecessor(II->getParent());
+}
+
+/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
+/// into the caller, update the specified callgraph to reflect the changes we
+/// made. Note that it's possible that not all code was copied over, so only
+/// some edges of the callgraph will be remain.
+static void UpdateCallGraphAfterInlining(const Function *Caller,
+ const Function *Callee,
+ Function::iterator FirstNewBlock,
+ DenseMap<const Value*, Value*> &ValueMap,
+ CallGraph &CG) {
+ // Update the call graph by deleting the edge from Callee to Caller
+ CallGraphNode *CalleeNode = CG[Callee];
+ CallGraphNode *CallerNode = CG[Caller];
+ CallerNode->removeCallEdgeTo(CalleeNode);
+
+ // Since we inlined some uninlined call sites in the callee into the caller,
+ // add edges from the caller to all of the callees of the callee.
+ for (CallGraphNode::iterator I = CalleeNode->begin(),
+ E = CalleeNode->end(); I != E; ++I) {
+ const Instruction *OrigCall = I->first.getInstruction();
+
+ DenseMap<const Value*, Value*>::iterator VMI = ValueMap.find(OrigCall);
+ // Only copy the edge if the call was inlined!
+ if (VMI != ValueMap.end() && VMI->second) {
+ // If the call was inlined, but then constant folded, there is no edge to
+ // add. Check for this case.
+ if (Instruction *NewCall = dyn_cast<Instruction>(VMI->second))
+ CallerNode->addCalledFunction(CallSite::get(NewCall), I->second);
+ }
+ }
+}
+
+
+// InlineFunction - This function inlines the called function into the basic
+// block of the caller. This returns false if it is not possible to inline this
+// call. The program is still in a well defined state if this occurs though.
+//
+// Note that this only does one level of inlining. For example, if the
+// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
+// exists in the instruction stream. Similiarly this will inline a recursive
+// function by one level.
+//
+bool llvm::InlineFunction(CallSite CS, CallGraph *CG, const TargetData *TD) {
+ Instruction *TheCall = CS.getInstruction();
+ assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
+ "Instruction not in function!");
+
+ const Function *CalledFunc = CS.getCalledFunction();
+ if (CalledFunc == 0 || // Can't inline external function or indirect
+ CalledFunc->isDeclaration() || // call, or call to a vararg function!
+ CalledFunc->getFunctionType()->isVarArg()) return false;
+
+
+ // If the call to the callee is a non-tail call, we must clear the 'tail'
+ // flags on any calls that we inline.
+ bool MustClearTailCallFlags =
+ isa<CallInst>(TheCall) && !cast<CallInst>(TheCall)->isTailCall();
+
+ BasicBlock *OrigBB = TheCall->getParent();
+ Function *Caller = OrigBB->getParent();
+
+ // Get an iterator to the last basic block in the function, which will have
+ // the new function inlined after it.
+ //
+ Function::iterator LastBlock = &Caller->back();
+
+ // Make sure to capture all of the return instructions from the cloned
+ // function.
+ std::vector<ReturnInst*> Returns;
+ ClonedCodeInfo InlinedFunctionInfo;
+ Function::iterator FirstNewBlock;
+
+ { // Scope to destroy ValueMap after cloning.
+ DenseMap<const Value*, Value*> ValueMap;
+
+ // Calculate the vector of arguments to pass into the function cloner, which
+ // matches up the formal to the actual argument values.
+ assert(std::distance(CalledFunc->arg_begin(), CalledFunc->arg_end()) ==
+ std::distance(CS.arg_begin(), CS.arg_end()) &&
+ "No varargs calls can be inlined!");
+ CallSite::arg_iterator AI = CS.arg_begin();
+ for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
+ E = CalledFunc->arg_end(); I != E; ++I, ++AI)
+ ValueMap[I] = *AI;
+
+ // We want the inliner to prune the code as it copies. We would LOVE to
+ // have no dead or constant instructions leftover after inlining occurs
+ // (which can happen, e.g., because an argument was constant), but we'll be
+ // happy with whatever the cloner can do.
+ CloneAndPruneFunctionInto(Caller, CalledFunc, ValueMap, Returns, ".i",
+ &InlinedFunctionInfo, TD);
+
+ // Remember the first block that is newly cloned over.
+ FirstNewBlock = LastBlock; ++FirstNewBlock;
+
+ // Update the callgraph if requested.
+ if (CG)
+ UpdateCallGraphAfterInlining(Caller, CalledFunc, FirstNewBlock, ValueMap,
+ *CG);
+ }
+
+ // If there are any alloca instructions in the block that used to be the entry
+ // block for the callee, move them to the entry block of the caller. First
+ // calculate which instruction they should be inserted before. We insert the
+ // instructions at the end of the current alloca list.
+ //
+ {
+ BasicBlock::iterator InsertPoint = Caller->begin()->begin();
+ for (BasicBlock::iterator I = FirstNewBlock->begin(),
+ E = FirstNewBlock->end(); I != E; )
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(I++)) {
+ // If the alloca is now dead, remove it. This often occurs due to code
+ // specialization.
+ if (AI->use_empty()) {
+ AI->eraseFromParent();
+ continue;
+ }
+
+ if (isa<Constant>(AI->getArraySize())) {
+ // Scan for the block of allocas that we can move over, and move them
+ // all at once.
+ while (isa<AllocaInst>(I) &&
+ isa<Constant>(cast<AllocaInst>(I)->getArraySize()))
+ ++I;
+
+ // Transfer all of the allocas over in a block. Using splice means
+ // that the instructions aren't removed from the symbol table, then
+ // reinserted.
+ Caller->getEntryBlock().getInstList().splice(
+ InsertPoint,
+ FirstNewBlock->getInstList(),
+ AI, I);
+ }
+ }
+ }
+
+ // If the inlined code contained dynamic alloca instructions, wrap the inlined
+ // code with llvm.stacksave/llvm.stackrestore intrinsics.
+ if (InlinedFunctionInfo.ContainsDynamicAllocas) {
+ Module *M = Caller->getParent();
+ const Type *BytePtr = PointerType::get(Type::Int8Ty);
+ // Get the two intrinsics we care about.
+ Constant *StackSave, *StackRestore;
+ StackSave = M->getOrInsertFunction("llvm.stacksave", BytePtr, NULL);
+ StackRestore = M->getOrInsertFunction("llvm.stackrestore", Type::VoidTy,
+ BytePtr, NULL);
+
+ // If we are preserving the callgraph, add edges to the stacksave/restore
+ // functions for the calls we insert.
+ CallGraphNode *StackSaveCGN = 0, *StackRestoreCGN = 0, *CallerNode = 0;
+ if (CG) {
+ // We know that StackSave/StackRestore are Function*'s, because they are
+ // intrinsics which must have the right types.
+ StackSaveCGN = CG->getOrInsertFunction(cast<Function>(StackSave));
+ StackRestoreCGN = CG->getOrInsertFunction(cast<Function>(StackRestore));
+ CallerNode = (*CG)[Caller];
+ }
+
+ // Insert the llvm.stacksave.
+ CallInst *SavedPtr = new CallInst(StackSave, "savedstack",
+ FirstNewBlock->begin());
+ if (CG) CallerNode->addCalledFunction(SavedPtr, StackSaveCGN);
+
+ // Insert a call to llvm.stackrestore before any return instructions in the
+ // inlined function.
+ for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
+ CallInst *CI = new CallInst(StackRestore, SavedPtr, "", Returns[i]);
+ if (CG) CallerNode->addCalledFunction(CI, StackRestoreCGN);
+ }
+
+ // Count the number of StackRestore calls we insert.
+ unsigned NumStackRestores = Returns.size();
+
+ // If we are inlining an invoke instruction, insert restores before each
+ // unwind. These unwinds will be rewritten into branches later.
+ if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) {
+ for (Function::iterator BB = FirstNewBlock, E = Caller->end();
+ BB != E; ++BB)
+ if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
+ new CallInst(StackRestore, SavedPtr, "", UI);
+ ++NumStackRestores;
+ }
+ }
+ }
+
+ // If we are inlining tail call instruction through a call site that isn't
+ // marked 'tail', we must remove the tail marker for any calls in the inlined
+ // code.
+ if (MustClearTailCallFlags && InlinedFunctionInfo.ContainsCalls) {
+ for (Function::iterator BB = FirstNewBlock, E = Caller->end();
+ BB != E; ++BB)
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+ if (CallInst *CI = dyn_cast<CallInst>(I))
+ CI->setTailCall(false);
+ }
+
+ // If we are inlining for an invoke instruction, we must make sure to rewrite
+ // any inlined 'unwind' instructions into branches to the invoke exception
+ // destination, and call instructions into invoke instructions.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
+ HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
+
+ // If we cloned in _exactly one_ basic block, and if that block ends in a
+ // return instruction, we splice the body of the inlined callee directly into
+ // the calling basic block.
+ if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
+ // Move all of the instructions right before the call.
+ OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
+ FirstNewBlock->begin(), FirstNewBlock->end());
+ // Remove the cloned basic block.
+ Caller->getBasicBlockList().pop_back();
+
+ // If the call site was an invoke instruction, add a branch to the normal
+ // destination.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
+ new BranchInst(II->getNormalDest(), TheCall);
+
+ // If the return instruction returned a value, replace uses of the call with
+ // uses of the returned value.
+ if (!TheCall->use_empty())
+ TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
+
+ // Since we are now done with the Call/Invoke, we can delete it.
+ TheCall->getParent()->getInstList().erase(TheCall);
+
+ // Since we are now done with the return instruction, delete it also.
+ Returns[0]->getParent()->getInstList().erase(Returns[0]);
+
+ // We are now done with the inlining.
+ return true;
+ }
+
+ // Otherwise, we have the normal case, of more than one block to inline or
+ // multiple return sites.
+
+ // We want to clone the entire callee function into the hole between the
+ // "starter" and "ender" blocks. How we accomplish this depends on whether
+ // this is an invoke instruction or a call instruction.
+ BasicBlock *AfterCallBB;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
+
+ // Add an unconditional branch to make this look like the CallInst case...
+ BranchInst *NewBr = new BranchInst(II->getNormalDest(), TheCall);
+
+ // Split the basic block. This guarantees that no PHI nodes will have to be
+ // updated due to new incoming edges, and make the invoke case more
+ // symmetric to the call case.
+ AfterCallBB = OrigBB->splitBasicBlock(NewBr,
+ CalledFunc->getName()+".exit");
+
+ } else { // It's a call
+ // If this is a call instruction, we need to split the basic block that
+ // the call lives in.
+ //
+ AfterCallBB = OrigBB->splitBasicBlock(TheCall,
+ CalledFunc->getName()+".exit");
+ }
+
+ // Change the branch that used to go to AfterCallBB to branch to the first
+ // basic block of the inlined function.
+ //
+ TerminatorInst *Br = OrigBB->getTerminator();
+ assert(Br && Br->getOpcode() == Instruction::Br &&
+ "splitBasicBlock broken!");
+ Br->setOperand(0, FirstNewBlock);
+
+
+ // Now that the function is correct, make it a little bit nicer. In
+ // particular, move the basic blocks inserted from the end of the function
+ // into the space made by splitting the source basic block.
+ //
+ Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
+ FirstNewBlock, Caller->end());
+
+ // Handle all of the return instructions that we just cloned in, and eliminate
+ // any users of the original call/invoke instruction.
+ if (Returns.size() > 1) {
+ // The PHI node should go at the front of the new basic block to merge all
+ // possible incoming values.
+ //
+ PHINode *PHI = 0;
+ if (!TheCall->use_empty()) {
+ PHI = new PHINode(CalledFunc->getReturnType(),
+ TheCall->getName(), AfterCallBB->begin());
+
+ // Anything that used the result of the function call should now use the
+ // PHI node as their operand.
+ //
+ TheCall->replaceAllUsesWith(PHI);
+ }
+
+ // Loop over all of the return instructions, turning them into unconditional
+ // branches to the merge point now, and adding entries to the PHI node as
+ // appropriate.
+ for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
+ ReturnInst *RI = Returns[i];
+
+ if (PHI) {
+ assert(RI->getReturnValue() && "Ret should have value!");
+ assert(RI->getReturnValue()->getType() == PHI->getType() &&
+ "Ret value not consistent in function!");
+ PHI->addIncoming(RI->getReturnValue(), RI->getParent());
+ }
+
+ // Add a branch to the merge point where the PHI node lives if it exists.
+ new BranchInst(AfterCallBB, RI);
+
+ // Delete the return instruction now
+ RI->getParent()->getInstList().erase(RI);
+ }
+
+ } else if (!Returns.empty()) {
+ // Otherwise, if there is exactly one return value, just replace anything
+ // using the return value of the call with the computed value.
+ if (!TheCall->use_empty())
+ TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
+
+ // Splice the code from the return block into the block that it will return
+ // to, which contains the code that was after the call.
+ BasicBlock *ReturnBB = Returns[0]->getParent();
+ AfterCallBB->getInstList().splice(AfterCallBB->begin(),
+ ReturnBB->getInstList());
+
+ // Update PHI nodes that use the ReturnBB to use the AfterCallBB.
+ ReturnBB->replaceAllUsesWith(AfterCallBB);
+
+ // Delete the return instruction now and empty ReturnBB now.
+ Returns[0]->eraseFromParent();
+ ReturnBB->eraseFromParent();
+ } else if (!TheCall->use_empty()) {
+ // No returns, but something is using the return value of the call. Just
+ // nuke the result.
+ TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
+ }
+
+ // Since we are now done with the Call/Invoke, we can delete it.
+ TheCall->eraseFromParent();
+
+ // We should always be able to fold the entry block of the function into the
+ // single predecessor of the block...
+ assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
+ BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
+
+ // Splice the code entry block into calling block, right before the
+ // unconditional branch.
+ OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
+ CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes
+
+ // Remove the unconditional branch.
+ OrigBB->getInstList().erase(Br);
+
+ // Now we can remove the CalleeEntry block, which is now empty.
+ Caller->getBasicBlockList().erase(CalleeEntry);
+
+ return true;
+}
diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
new file mode 100644
index 0000000..220241d
--- /dev/null
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -0,0 +1,269 @@
+//===-- LCSSA.cpp - Convert loops into loop-closed SSA form ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass transforms loops by placing phi nodes at the end of the loops for
+// all values that are live across the loop boundary. For example, it turns
+// the left into the right code:
+//
+// for (...) for (...)
+// if (c) if (c)
+// X1 = ... X1 = ...
+// else else
+// X2 = ... X2 = ...
+// X3 = phi(X1, X2) X3 = phi(X1, X2)
+// ... = X3 + 4 X4 = phi(X3)
+// ... = X4 + 4
+//
+// This is still valid LLVM; the extra phi nodes are purely redundant, and will
+// be trivially eliminated by InstCombine. The major benefit of this
+// transformation is that it makes many other loop optimizations, such as
+// LoopUnswitching, simpler.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lcssa"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constants.h"
+#include "llvm/Pass.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include <algorithm>
+#include <map>
+using namespace llvm;
+
+STATISTIC(NumLCSSA, "Number of live out of a loop variables");
+
+namespace {
+ struct VISIBILITY_HIDDEN LCSSA : public LoopPass {
+ static char ID; // Pass identification, replacement for typeid
+ LCSSA() : LoopPass((intptr_t)&ID) {}
+
+ // Cached analysis information for the current function.
+ LoopInfo *LI;
+ DominatorTree *DT;
+ std::vector<BasicBlock*> LoopBlocks;
+
+ virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
+
+ void ProcessInstruction(Instruction* Instr,
+ const std::vector<BasicBlock*>& exitBlocks);
+
+ /// This transformation requires natural loop information & requires that
+ /// loop preheaders be inserted into the CFG. It maintains both of these,
+ /// as well as the CFG. It also requires dominator information.
+ ///
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addPreservedID(LoopSimplifyID);
+ AU.addRequired<LoopInfo>();
+ AU.addPreserved<LoopInfo>();
+ AU.addRequired<DominatorTree>();
+ AU.addPreserved<ScalarEvolution>();
+ }
+ private:
+ void getLoopValuesUsedOutsideLoop(Loop *L,
+ SetVector<Instruction*> &AffectedValues);
+
+ Value *GetValueForBlock(DomTreeNode *BB, Instruction *OrigInst,
+ std::map<DomTreeNode*, Value*> &Phis);
+
+ /// inLoop - returns true if the given block is within the current loop
+ const bool inLoop(BasicBlock* B) {
+ return std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), B);
+ }
+ };
+
+ char LCSSA::ID = 0;
+ RegisterPass<LCSSA> X("lcssa", "Loop-Closed SSA Form Pass");
+}
+
+LoopPass *llvm::createLCSSAPass() { return new LCSSA(); }
+const PassInfo *llvm::LCSSAID = X.getPassInfo();
+
+/// runOnFunction - Process all loops in the function, inner-most out.
+bool LCSSA::runOnLoop(Loop *L, LPPassManager &LPM) {
+
+ LI = &LPM.getAnalysis<LoopInfo>();
+ DT = &getAnalysis<DominatorTree>();
+
+ // Speed up queries by creating a sorted list of blocks
+ LoopBlocks.clear();
+ LoopBlocks.insert(LoopBlocks.end(), L->block_begin(), L->block_end());
+ std::sort(LoopBlocks.begin(), LoopBlocks.end());
+
+ SetVector<Instruction*> AffectedValues;
+ getLoopValuesUsedOutsideLoop(L, AffectedValues);
+
+ // If no values are affected, we can save a lot of work, since we know that
+ // nothing will be changed.
+ if (AffectedValues.empty())
+ return false;
+
+ std::vector<BasicBlock*> exitBlocks;
+ L->getExitBlocks(exitBlocks);
+
+
+ // Iterate over all affected values for this loop and insert Phi nodes
+ // for them in the appropriate exit blocks
+
+ for (SetVector<Instruction*>::iterator I = AffectedValues.begin(),
+ E = AffectedValues.end(); I != E; ++I)
+ ProcessInstruction(*I, exitBlocks);
+
+ assert(L->isLCSSAForm());
+
+ return true;
+}
+
+/// processInstruction - Given a live-out instruction, insert LCSSA Phi nodes,
+/// eliminate all out-of-loop uses.
+void LCSSA::ProcessInstruction(Instruction *Instr,
+ const std::vector<BasicBlock*>& exitBlocks) {
+ ++NumLCSSA; // We are applying the transformation
+
+ // Keep track of the blocks that have the value available already.
+ std::map<DomTreeNode*, Value*> Phis;
+
+ DomTreeNode *InstrNode = DT->getNode(Instr->getParent());
+
+ // Insert the LCSSA phi's into the exit blocks (dominated by the value), and
+ // add them to the Phi's map.
+ for (std::vector<BasicBlock*>::const_iterator BBI = exitBlocks.begin(),
+ BBE = exitBlocks.end(); BBI != BBE; ++BBI) {
+ BasicBlock *BB = *BBI;
+ DomTreeNode *ExitBBNode = DT->getNode(BB);
+ Value *&Phi = Phis[ExitBBNode];
+ if (!Phi && DT->dominates(InstrNode, ExitBBNode)) {
+ PHINode *PN = new PHINode(Instr->getType(), Instr->getName()+".lcssa",
+ BB->begin());
+ PN->reserveOperandSpace(std::distance(pred_begin(BB), pred_end(BB)));
+
+ // Remember that this phi makes the value alive in this block.
+ Phi = PN;
+
+ // Add inputs from inside the loop for this PHI.
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ PN->addIncoming(Instr, *PI);
+ }
+ }
+
+
+ // Record all uses of Instr outside the loop. We need to rewrite these. The
+ // LCSSA phis won't be included because they use the value in the loop.
+ for (Value::use_iterator UI = Instr->use_begin(), E = Instr->use_end();
+ UI != E;) {
+ BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
+ if (PHINode *P = dyn_cast<PHINode>(*UI)) {
+ unsigned OperandNo = UI.getOperandNo();
+ UserBB = P->getIncomingBlock(OperandNo/2);
+ }
+
+ // If the user is in the loop, don't rewrite it!
+ if (UserBB == Instr->getParent() || inLoop(UserBB)) {
+ ++UI;
+ continue;
+ }
+
+ // Otherwise, patch up uses of the value with the appropriate LCSSA Phi,
+ // inserting PHI nodes into join points where needed.
+ Value *Val = GetValueForBlock(DT->getNode(UserBB), Instr, Phis);
+
+ // Preincrement the iterator to avoid invalidating it when we change the
+ // value.
+ Use &U = UI.getUse();
+ ++UI;
+ U.set(Val);
+ }
+}
+
+/// getLoopValuesUsedOutsideLoop - Return any values defined in the loop that
+/// are used by instructions outside of it.
+void LCSSA::getLoopValuesUsedOutsideLoop(Loop *L,
+ SetVector<Instruction*> &AffectedValues) {
+ // FIXME: For large loops, we may be able to avoid a lot of use-scanning
+ // by using dominance information. In particular, if a block does not
+ // dominate any of the loop exits, then none of the values defined in the
+ // block could be used outside the loop.
+ for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
+ BB != E; ++BB) {
+ for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I)
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
+ ++UI) {
+ BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
+ if (PHINode* p = dyn_cast<PHINode>(*UI)) {
+ unsigned OperandNo = UI.getOperandNo();
+ UserBB = p->getIncomingBlock(OperandNo/2);
+ }
+
+ if (*BB != UserBB && !inLoop(UserBB)) {
+ AffectedValues.insert(I);
+ break;
+ }
+ }
+ }
+}
+
+/// GetValueForBlock - Get the value to use within the specified basic block.
+/// available values are in Phis.
+Value *LCSSA::GetValueForBlock(DomTreeNode *BB, Instruction *OrigInst,
+ std::map<DomTreeNode*, Value*> &Phis) {
+ // If there is no dominator info for this BB, it is unreachable.
+ if (BB == 0)
+ return UndefValue::get(OrigInst->getType());
+
+ // If we have already computed this value, return the previously computed val.
+ Value *&V = Phis[BB];
+ if (V) return V;
+
+ DomTreeNode *IDom = BB->getIDom();
+
+ // If the block has no dominator, bail
+ if (!IDom)
+ return V = UndefValue::get(OrigInst->getType());
+
+ // Otherwise, there are two cases: we either have to insert a PHI node or we
+ // don't. We need to insert a PHI node if this block is not dominated by one
+ // of the exit nodes from the loop (the loop could have multiple exits, and
+ // though the value defined *inside* the loop dominated all its uses, each
+ // exit by itself may not dominate all the uses).
+ //
+ // The simplest way to check for this condition is by checking to see if the
+ // idom is in the loop. If so, we *know* that none of the exit blocks
+ // dominate this block. Note that we *know* that the block defining the
+ // original instruction is in the idom chain, because if it weren't, then the
+ // original value didn't dominate this use.
+ if (!inLoop(IDom->getBlock())) {
+ // Idom is not in the loop, we must still be "below" the exit block and must
+ // be fully dominated by the value live in the idom.
+ return V = GetValueForBlock(IDom, OrigInst, Phis);
+ }
+
+ BasicBlock *BBN = BB->getBlock();
+
+ // Otherwise, the idom is the loop, so we need to insert a PHI node. Do so
+ // now, then get values to fill in the incoming values for the PHI.
+ PHINode *PN = new PHINode(OrigInst->getType(), OrigInst->getName()+".lcssa",
+ BBN->begin());
+ PN->reserveOperandSpace(std::distance(pred_begin(BBN), pred_end(BBN)));
+ V = PN;
+
+ // Fill in the incoming values for the block.
+ for (pred_iterator PI = pred_begin(BBN), E = pred_end(BBN); PI != E; ++PI)
+ PN->addIncoming(GetValueForBlock(DT->getNode(*PI), OrigInst, Phis), *PI);
+ return PN;
+}
+
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
new file mode 100644
index 0000000..5e2d237
--- /dev/null
+++ b/lib/Transforms/Utils/Local.cpp
@@ -0,0 +1,200 @@
+//===-- Local.cpp - Functions to perform local transformations ------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This family of functions perform various local transformations to the
+// program.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/MathExtras.h"
+#include <cerrno>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// Local constant propagation...
+//
+
+/// doConstantPropagation - If an instruction references constants, try to fold
+/// them together...
+///
+bool llvm::doConstantPropagation(BasicBlock::iterator &II,
+ const TargetData *TD) {
+ if (Constant *C = ConstantFoldInstruction(II, TD)) {
+ // Replaces all of the uses of a variable with uses of the constant.
+ II->replaceAllUsesWith(C);
+
+ // Remove the instruction from the basic block...
+ II = II->getParent()->getInstList().erase(II);
+ return true;
+ }
+
+ return false;
+}
+
+// ConstantFoldTerminator - If a terminator instruction is predicated on a
+// constant value, convert it into an unconditional branch to the constant
+// destination.
+//
+bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
+ TerminatorInst *T = BB->getTerminator();
+
+ // Branch - See if we are conditional jumping on constant
+ if (BranchInst *BI = dyn_cast<BranchInst>(T)) {
+ if (BI->isUnconditional()) return false; // Can't optimize uncond branch
+ BasicBlock *Dest1 = cast<BasicBlock>(BI->getOperand(0));
+ BasicBlock *Dest2 = cast<BasicBlock>(BI->getOperand(1));
+
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition())) {
+ // Are we branching on constant?
+ // YES. Change to unconditional branch...
+ BasicBlock *Destination = Cond->getZExtValue() ? Dest1 : Dest2;
+ BasicBlock *OldDest = Cond->getZExtValue() ? Dest2 : Dest1;
+
+ //cerr << "Function: " << T->getParent()->getParent()
+ // << "\nRemoving branch from " << T->getParent()
+ // << "\n\nTo: " << OldDest << endl;
+
+ // Let the basic block know that we are letting go of it. Based on this,
+ // it will adjust it's PHI nodes.
+ assert(BI->getParent() && "Terminator not inserted in block!");
+ OldDest->removePredecessor(BI->getParent());
+
+ // Set the unconditional destination, and change the insn to be an
+ // unconditional branch.
+ BI->setUnconditionalDest(Destination);
+ return true;
+ } else if (Dest2 == Dest1) { // Conditional branch to same location?
+ // This branch matches something like this:
+ // br bool %cond, label %Dest, label %Dest
+ // and changes it into: br label %Dest
+
+ // Let the basic block know that we are letting go of one copy of it.
+ assert(BI->getParent() && "Terminator not inserted in block!");
+ Dest1->removePredecessor(BI->getParent());
+
+ // Change a conditional branch to unconditional.
+ BI->setUnconditionalDest(Dest1);
+ return true;
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(T)) {
+ // If we are switching on a constant, we can convert the switch into a
+ // single branch instruction!
+ ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
+ BasicBlock *TheOnlyDest = SI->getSuccessor(0); // The default dest
+ BasicBlock *DefaultDest = TheOnlyDest;
+ assert(TheOnlyDest == SI->getDefaultDest() &&
+ "Default destination is not successor #0?");
+
+ // Figure out which case it goes to...
+ for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
+ // Found case matching a constant operand?
+ if (SI->getSuccessorValue(i) == CI) {
+ TheOnlyDest = SI->getSuccessor(i);
+ break;
+ }
+
+ // Check to see if this branch is going to the same place as the default
+ // dest. If so, eliminate it as an explicit compare.
+ if (SI->getSuccessor(i) == DefaultDest) {
+ // Remove this entry...
+ DefaultDest->removePredecessor(SI->getParent());
+ SI->removeCase(i);
+ --i; --e; // Don't skip an entry...
+ continue;
+ }
+
+ // Otherwise, check to see if the switch only branches to one destination.
+ // We do this by reseting "TheOnlyDest" to null when we find two non-equal
+ // destinations.
+ if (SI->getSuccessor(i) != TheOnlyDest) TheOnlyDest = 0;
+ }
+
+ if (CI && !TheOnlyDest) {
+ // Branching on a constant, but not any of the cases, go to the default
+ // successor.
+ TheOnlyDest = SI->getDefaultDest();
+ }
+
+ // If we found a single destination that we can fold the switch into, do so
+ // now.
+ if (TheOnlyDest) {
+ // Insert the new branch..
+ new BranchInst(TheOnlyDest, SI);
+ BasicBlock *BB = SI->getParent();
+
+ // Remove entries from PHI nodes which we no longer branch to...
+ for (unsigned i = 0, e = SI->getNumSuccessors(); i != e; ++i) {
+ // Found case matching a constant operand?
+ BasicBlock *Succ = SI->getSuccessor(i);
+ if (Succ == TheOnlyDest)
+ TheOnlyDest = 0; // Don't modify the first branch to TheOnlyDest
+ else
+ Succ->removePredecessor(BB);
+ }
+
+ // Delete the old switch...
+ BB->getInstList().erase(SI);
+ return true;
+ } else if (SI->getNumSuccessors() == 2) {
+ // Otherwise, we can fold this switch into a conditional branch
+ // instruction if it has only one non-default destination.
+ Value *Cond = new ICmpInst(ICmpInst::ICMP_EQ, SI->getCondition(),
+ SI->getSuccessorValue(1), "cond", SI);
+ // Insert the new branch...
+ new BranchInst(SI->getSuccessor(1), SI->getSuccessor(0), Cond, SI);
+
+ // Delete the old switch...
+ SI->getParent()->getInstList().erase(SI);
+ return true;
+ }
+ }
+ return false;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Local dead code elimination...
+//
+
+bool llvm::isInstructionTriviallyDead(Instruction *I) {
+ if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
+
+ if (!I->mayWriteToMemory()) return true;
+
+ if (CallInst *CI = dyn_cast<CallInst>(I))
+ if (Function *F = CI->getCalledFunction()) {
+ unsigned IntrinsicID = F->getIntrinsicID();
+#define GET_SIDE_EFFECT_INFO
+#include "llvm/Intrinsics.gen"
+#undef GET_SIDE_EFFECT_INFO
+ }
+ return false;
+}
+
+// dceInstruction - Inspect the instruction at *BBI and figure out if it's
+// [trivially] dead. If so, remove the instruction and update the iterator
+// to point to the instruction that immediately succeeded the original
+// instruction.
+//
+bool llvm::dceInstruction(BasicBlock::iterator &BBI) {
+ // Look for un"used" definitions...
+ if (isInstructionTriviallyDead(BBI)) {
+ BBI = BBI->getParent()->getInstList().erase(BBI); // Bye bye
+ return true;
+ }
+ return false;
+}
diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
new file mode 100644
index 0000000..0a5de2b
--- /dev/null
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -0,0 +1,692 @@
+//===- LoopSimplify.cpp - Loop Canonicalization Pass ----------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass performs several transformations to transform natural loops into a
+// simpler form, which makes subsequent analyses and transformations simpler and
+// more effective.
+//
+// Loop pre-header insertion guarantees that there is a single, non-critical
+// entry edge from outside of the loop to the loop header. This simplifies a
+// number of analyses and transformations, such as LICM.
+//
+// Loop exit-block insertion guarantees that all exit blocks from the loop
+// (blocks which are outside of the loop that have predecessors inside of the
+// loop) only have predecessors from inside of the loop (and are thus dominated
+// by the loop header). This simplifies transformations such as store-sinking
+// that are built into LICM.
+//
+// This pass also guarantees that loops will have exactly one backedge.
+//
+// Note that the simplifycfg pass will clean up blocks which are split out but
+// end up being unnecessary, so usage of this pass should not pessimize
+// generated code.
+//
+// This pass obviously modifies the CFG, but updates loop information and
+// dominator information.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "loopsimplify"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constant.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "llvm/Type.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/SetOperations.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+using namespace llvm;
+
+STATISTIC(NumInserted, "Number of pre-header or exit blocks inserted");
+STATISTIC(NumNested , "Number of nested loops split out");
+
+namespace {
+ struct VISIBILITY_HIDDEN LoopSimplify : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ LoopSimplify() : FunctionPass((intptr_t)&ID) {}
+
+ // AA - If we have an alias analysis object to update, this is it, otherwise
+ // this is null.
+ AliasAnalysis *AA;
+ LoopInfo *LI;
+ DominatorTree *DT;
+ virtual bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // We need loop information to identify the loops...
+ AU.addRequired<LoopInfo>();
+ AU.addRequired<DominatorTree>();
+
+ AU.addPreserved<LoopInfo>();
+ AU.addPreserved<DominatorTree>();
+ AU.addPreserved<DominanceFrontier>();
+ AU.addPreservedID(BreakCriticalEdgesID); // No critical edges added.
+ }
+ private:
+ bool ProcessLoop(Loop *L);
+ BasicBlock *SplitBlockPredecessors(BasicBlock *BB, const char *Suffix,
+ const std::vector<BasicBlock*> &Preds);
+ BasicBlock *RewriteLoopExitBlock(Loop *L, BasicBlock *Exit);
+ void InsertPreheaderForLoop(Loop *L);
+ Loop *SeparateNestedLoop(Loop *L);
+ void InsertUniqueBackedgeBlock(Loop *L);
+ void PlaceSplitBlockCarefully(BasicBlock *NewBB,
+ std::vector<BasicBlock*> &SplitPreds,
+ Loop *L);
+ };
+
+ char LoopSimplify::ID = 0;
+ RegisterPass<LoopSimplify>
+ X("loopsimplify", "Canonicalize natural loops", true);
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LoopSimplifyID = X.getPassInfo();
+FunctionPass *llvm::createLoopSimplifyPass() { return new LoopSimplify(); }
+
+/// runOnFunction - Run down all loops in the CFG (recursively, but we could do
+/// it in any convenient order) inserting preheaders...
+///
+bool LoopSimplify::runOnFunction(Function &F) {
+ bool Changed = false;
+ LI = &getAnalysis<LoopInfo>();
+ AA = getAnalysisToUpdate<AliasAnalysis>();
+ DT = &getAnalysis<DominatorTree>();
+
+ // Check to see that no blocks (other than the header) in loops have
+ // predecessors that are not in loops. This is not valid for natural loops,
+ // but can occur if the blocks are unreachable. Since they are unreachable we
+ // can just shamelessly destroy their terminators to make them not branch into
+ // the loop!
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ // This case can only occur for unreachable blocks. Blocks that are
+ // unreachable can't be in loops, so filter those blocks out.
+ if (LI->getLoopFor(BB)) continue;
+
+ bool BlockUnreachable = false;
+ TerminatorInst *TI = BB->getTerminator();
+
+ // Check to see if any successors of this block are non-loop-header loops
+ // that are not the header.
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
+ // If this successor is not in a loop, BB is clearly ok.
+ Loop *L = LI->getLoopFor(TI->getSuccessor(i));
+ if (!L) continue;
+
+ // If the succ is the loop header, and if L is a top-level loop, then this
+ // is an entrance into a loop through the header, which is also ok.
+ if (L->getHeader() == TI->getSuccessor(i) && L->getParentLoop() == 0)
+ continue;
+
+ // Otherwise, this is an entrance into a loop from some place invalid.
+ // Either the loop structure is invalid and this is not a natural loop (in
+ // which case the compiler is buggy somewhere else) or BB is unreachable.
+ BlockUnreachable = true;
+ break;
+ }
+
+ // If this block is ok, check the next one.
+ if (!BlockUnreachable) continue;
+
+ // Otherwise, this block is dead. To clean up the CFG and to allow later
+ // loop transformations to ignore this case, we delete the edges into the
+ // loop by replacing the terminator.
+
+ // Remove PHI entries from the successors.
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ TI->getSuccessor(i)->removePredecessor(BB);
+
+ // Add a new unreachable instruction.
+ new UnreachableInst(TI);
+
+ // Delete the dead terminator.
+ if (AA) AA->deleteValue(&BB->back());
+ BB->getInstList().pop_back();
+ Changed |= true;
+ }
+
+ for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
+ Changed |= ProcessLoop(*I);
+
+ return Changed;
+}
+
+/// ProcessLoop - Walk the loop structure in depth first order, ensuring that
+/// all loops have preheaders.
+///
+bool LoopSimplify::ProcessLoop(Loop *L) {
+ bool Changed = false;
+ReprocessLoop:
+
+ // Canonicalize inner loops before outer loops. Inner loop canonicalization
+ // can provide work for the outer loop to canonicalize.
+ for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
+ Changed |= ProcessLoop(*I);
+
+ assert(L->getBlocks()[0] == L->getHeader() &&
+ "Header isn't first block in loop?");
+
+ // Does the loop already have a preheader? If so, don't insert one.
+ if (L->getLoopPreheader() == 0) {
+ InsertPreheaderForLoop(L);
+ NumInserted++;
+ Changed = true;
+ }
+
+ // Next, check to make sure that all exit nodes of the loop only have
+ // predecessors that are inside of the loop. This check guarantees that the
+ // loop preheader/header will dominate the exit blocks. If the exit block has
+ // predecessors from outside of the loop, split the edge now.
+ std::vector<BasicBlock*> ExitBlocks;
+ L->getExitBlocks(ExitBlocks);
+
+ SetVector<BasicBlock*> ExitBlockSet(ExitBlocks.begin(), ExitBlocks.end());
+ for (SetVector<BasicBlock*>::iterator I = ExitBlockSet.begin(),
+ E = ExitBlockSet.end(); I != E; ++I) {
+ BasicBlock *ExitBlock = *I;
+ for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
+ PI != PE; ++PI)
+ // Must be exactly this loop: no subloops, parent loops, or non-loop preds
+ // allowed.
+ if (!L->contains(*PI)) {
+ RewriteLoopExitBlock(L, ExitBlock);
+ NumInserted++;
+ Changed = true;
+ break;
+ }
+ }
+
+ // If the header has more than two predecessors at this point (from the
+ // preheader and from multiple backedges), we must adjust the loop.
+ unsigned NumBackedges = L->getNumBackEdges();
+ if (NumBackedges != 1) {
+ // If this is really a nested loop, rip it out into a child loop. Don't do
+ // this for loops with a giant number of backedges, just factor them into a
+ // common backedge instead.
+ if (NumBackedges < 8) {
+ if (Loop *NL = SeparateNestedLoop(L)) {
+ ++NumNested;
+ // This is a big restructuring change, reprocess the whole loop.
+ ProcessLoop(NL);
+ Changed = true;
+ // GCC doesn't tail recursion eliminate this.
+ goto ReprocessLoop;
+ }
+ }
+
+ // If we either couldn't, or didn't want to, identify nesting of the loops,
+ // insert a new block that all backedges target, then make it jump to the
+ // loop header.
+ InsertUniqueBackedgeBlock(L);
+ NumInserted++;
+ Changed = true;
+ }
+
+ // Scan over the PHI nodes in the loop header. Since they now have only two
+ // incoming values (the loop is canonicalized), we may have simplified the PHI
+ // down to 'X = phi [X, Y]', which should be replaced with 'Y'.
+ PHINode *PN;
+ for (BasicBlock::iterator I = L->getHeader()->begin();
+ (PN = dyn_cast<PHINode>(I++)); )
+ if (Value *V = PN->hasConstantValue()) {
+ PN->replaceAllUsesWith(V);
+ PN->eraseFromParent();
+ }
+
+ return Changed;
+}
+
+/// SplitBlockPredecessors - Split the specified block into two blocks. We want
+/// to move the predecessors specified in the Preds list to point to the new
+/// block, leaving the remaining predecessors pointing to BB. This method
+/// updates the SSA PHINode's, but no other analyses.
+///
+BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
+ const char *Suffix,
+ const std::vector<BasicBlock*> &Preds) {
+
+ // Create new basic block, insert right before the original block...
+ BasicBlock *NewBB = new BasicBlock(BB->getName()+Suffix, BB->getParent(), BB);
+
+ // The preheader first gets an unconditional branch to the loop header...
+ BranchInst *BI = new BranchInst(BB, NewBB);
+
+ // For every PHI node in the block, insert a PHI node into NewBB where the
+ // incoming values from the out of loop edges are moved to NewBB. We have two
+ // possible cases here. If the loop is dead, we just insert dummy entries
+ // into the PHI nodes for the new edge. If the loop is not dead, we move the
+ // incoming edges in BB into new PHI nodes in NewBB.
+ //
+ if (!Preds.empty()) { // Is the loop not obviously dead?
+ // Check to see if the values being merged into the new block need PHI
+ // nodes. If so, insert them.
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) {
+ PHINode *PN = cast<PHINode>(I);
+ ++I;
+
+ // Check to see if all of the values coming in are the same. If so, we
+ // don't need to create a new PHI node.
+ Value *InVal = PN->getIncomingValueForBlock(Preds[0]);
+ for (unsigned i = 1, e = Preds.size(); i != e; ++i)
+ if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
+ InVal = 0;
+ break;
+ }
+
+ // If the values coming into the block are not the same, we need a PHI.
+ if (InVal == 0) {
+ // Create the new PHI node, insert it into NewBB at the end of the block
+ PHINode *NewPHI = new PHINode(PN->getType(), PN->getName()+".ph", BI);
+ if (AA) AA->copyValue(PN, NewPHI);
+
+ // Move all of the edges from blocks outside the loop to the new PHI
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
+ Value *V = PN->removeIncomingValue(Preds[i], false);
+ NewPHI->addIncoming(V, Preds[i]);
+ }
+ InVal = NewPHI;
+ } else {
+ // Remove all of the edges coming into the PHI nodes from outside of the
+ // block.
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i)
+ PN->removeIncomingValue(Preds[i], false);
+ }
+
+ // Add an incoming value to the PHI node in the loop for the preheader
+ // edge.
+ PN->addIncoming(InVal, NewBB);
+
+ // Can we eliminate this phi node now?
+ if (Value *V = PN->hasConstantValue(true)) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ // If I is in NewBB, the Dominator call will fail, because NewBB isn't
+ // registered in DominatorTree yet. Handle this case explicitly.
+ if (!I || (I->getParent() != NewBB &&
+ getAnalysis<DominatorTree>().dominates(I, PN))) {
+ PN->replaceAllUsesWith(V);
+ if (AA) AA->deleteValue(PN);
+ BB->getInstList().erase(PN);
+ }
+ }
+ }
+
+ // Now that the PHI nodes are updated, actually move the edges from
+ // Preds to point to NewBB instead of BB.
+ //
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
+ TerminatorInst *TI = Preds[i]->getTerminator();
+ for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s)
+ if (TI->getSuccessor(s) == BB)
+ TI->setSuccessor(s, NewBB);
+ }
+
+ } else { // Otherwise the loop is dead...
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ // Insert dummy values as the incoming value...
+ PN->addIncoming(Constant::getNullValue(PN->getType()), NewBB);
+ }
+ }
+
+ return NewBB;
+}
+
+/// InsertPreheaderForLoop - Once we discover that a loop doesn't have a
+/// preheader, this method is called to insert one. This method has two phases:
+/// preheader insertion and analysis updating.
+///
+void LoopSimplify::InsertPreheaderForLoop(Loop *L) {
+ BasicBlock *Header = L->getHeader();
+
+ // Compute the set of predecessors of the loop that are not in the loop.
+ std::vector<BasicBlock*> OutsideBlocks;
+ for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+ PI != PE; ++PI)
+ if (!L->contains(*PI)) // Coming in from outside the loop?
+ OutsideBlocks.push_back(*PI); // Keep track of it...
+
+ // Split out the loop pre-header.
+ BasicBlock *NewBB =
+ SplitBlockPredecessors(Header, ".preheader", OutsideBlocks);
+
+
+ //===--------------------------------------------------------------------===//
+ // Update analysis results now that we have performed the transformation
+ //
+
+ // We know that we have loop information to update... update it now.
+ if (Loop *Parent = L->getParentLoop())
+ Parent->addBasicBlockToLoop(NewBB, *LI);
+
+ DT->splitBlock(NewBB);
+ if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>())
+ DF->splitBlock(NewBB);
+
+ // Make sure that NewBB is put someplace intelligent, which doesn't mess up
+ // code layout too horribly.
+ PlaceSplitBlockCarefully(NewBB, OutsideBlocks, L);
+}
+
+/// RewriteLoopExitBlock - Ensure that the loop preheader dominates all exit
+/// blocks. This method is used to split exit blocks that have predecessors
+/// outside of the loop.
+BasicBlock *LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
+ std::vector<BasicBlock*> LoopBlocks;
+ for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I)
+ if (L->contains(*I))
+ LoopBlocks.push_back(*I);
+
+ assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
+ BasicBlock *NewBB = SplitBlockPredecessors(Exit, ".loopexit", LoopBlocks);
+
+ // Update Loop Information - we know that the new block will be in whichever
+ // loop the Exit block is in. Note that it may not be in that immediate loop,
+ // if the successor is some other loop header. In that case, we continue
+ // walking up the loop tree to find a loop that contains both the successor
+ // block and the predecessor block.
+ Loop *SuccLoop = LI->getLoopFor(Exit);
+ while (SuccLoop && !SuccLoop->contains(L->getHeader()))
+ SuccLoop = SuccLoop->getParentLoop();
+ if (SuccLoop)
+ SuccLoop->addBasicBlockToLoop(NewBB, *LI);
+
+ // Update Dominator Information
+ DT->splitBlock(NewBB);
+ if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>())
+ DF->splitBlock(NewBB);
+
+ return NewBB;
+}
+
+/// AddBlockAndPredsToSet - Add the specified block, and all of its
+/// predecessors, to the specified set, if it's not already in there. Stop
+/// predecessor traversal when we reach StopBlock.
+static void AddBlockAndPredsToSet(BasicBlock *InputBB, BasicBlock *StopBlock,
+ std::set<BasicBlock*> &Blocks) {
+ std::vector<BasicBlock *> WorkList;
+ WorkList.push_back(InputBB);
+ do {
+ BasicBlock *BB = WorkList.back(); WorkList.pop_back();
+ if (Blocks.insert(BB).second && BB != StopBlock)
+ // If BB is not already processed and it is not a stop block then
+ // insert its predecessor in the work list
+ for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
+ BasicBlock *WBB = *I;
+ WorkList.push_back(WBB);
+ }
+ } while(!WorkList.empty());
+}
+
+/// FindPHIToPartitionLoops - The first part of loop-nestification is to find a
+/// PHI node that tells us how to partition the loops.
+static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorTree *DT,
+ AliasAnalysis *AA) {
+ for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
+ PHINode *PN = cast<PHINode>(I);
+ ++I;
+ if (Value *V = PN->hasConstantValue())
+ if (!isa<Instruction>(V) || DT->dominates(cast<Instruction>(V), PN)) {
+ // This is a degenerate PHI already, don't modify it!
+ PN->replaceAllUsesWith(V);
+ if (AA) AA->deleteValue(PN);
+ PN->eraseFromParent();
+ continue;
+ }
+
+ // Scan this PHI node looking for a use of the PHI node by itself.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (PN->getIncomingValue(i) == PN &&
+ L->contains(PN->getIncomingBlock(i)))
+ // We found something tasty to remove.
+ return PN;
+ }
+ return 0;
+}
+
+// PlaceSplitBlockCarefully - If the block isn't already, move the new block to
+// right after some 'outside block' block. This prevents the preheader from
+// being placed inside the loop body, e.g. when the loop hasn't been rotated.
+void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
+ std::vector<BasicBlock*>&SplitPreds,
+ Loop *L) {
+ // Check to see if NewBB is already well placed.
+ Function::iterator BBI = NewBB; --BBI;
+ for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
+ if (&*BBI == SplitPreds[i])
+ return;
+ }
+
+ // If it isn't already after an outside block, move it after one. This is
+ // always good as it makes the uncond branch from the outside block into a
+ // fall-through.
+
+ // Figure out *which* outside block to put this after. Prefer an outside
+ // block that neighbors a BB actually in the loop.
+ BasicBlock *FoundBB = 0;
+ for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
+ Function::iterator BBI = SplitPreds[i];
+ if (++BBI != NewBB->getParent()->end() &&
+ L->contains(BBI)) {
+ FoundBB = SplitPreds[i];
+ break;
+ }
+ }
+
+ // If our heuristic for a *good* bb to place this after doesn't find
+ // anything, just pick something. It's likely better than leaving it within
+ // the loop.
+ if (!FoundBB)
+ FoundBB = SplitPreds[0];
+ NewBB->moveAfter(FoundBB);
+}
+
+
+/// SeparateNestedLoop - If this loop has multiple backedges, try to pull one of
+/// them out into a nested loop. This is important for code that looks like
+/// this:
+///
+/// Loop:
+/// ...
+/// br cond, Loop, Next
+/// ...
+/// br cond2, Loop, Out
+///
+/// To identify this common case, we look at the PHI nodes in the header of the
+/// loop. PHI nodes with unchanging values on one backedge correspond to values
+/// that change in the "outer" loop, but not in the "inner" loop.
+///
+/// If we are able to separate out a loop, return the new outer loop that was
+/// created.
+///
+Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
+ PHINode *PN = FindPHIToPartitionLoops(L, DT, AA);
+ if (PN == 0) return 0; // No known way to partition.
+
+ // Pull out all predecessors that have varying values in the loop. This
+ // handles the case when a PHI node has multiple instances of itself as
+ // arguments.
+ std::vector<BasicBlock*> OuterLoopPreds;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (PN->getIncomingValue(i) != PN ||
+ !L->contains(PN->getIncomingBlock(i)))
+ OuterLoopPreds.push_back(PN->getIncomingBlock(i));
+
+ BasicBlock *Header = L->getHeader();
+ BasicBlock *NewBB = SplitBlockPredecessors(Header, ".outer", OuterLoopPreds);
+
+ // Update dominator information
+ DT->splitBlock(NewBB);
+ if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>())
+ DF->splitBlock(NewBB);
+
+ // Make sure that NewBB is put someplace intelligent, which doesn't mess up
+ // code layout too horribly.
+ PlaceSplitBlockCarefully(NewBB, OuterLoopPreds, L);
+
+ // Create the new outer loop.
+ Loop *NewOuter = new Loop();
+
+ // Change the parent loop to use the outer loop as its child now.
+ if (Loop *Parent = L->getParentLoop())
+ Parent->replaceChildLoopWith(L, NewOuter);
+ else
+ LI->changeTopLevelLoop(L, NewOuter);
+
+ // This block is going to be our new header block: add it to this loop and all
+ // parent loops.
+ NewOuter->addBasicBlockToLoop(NewBB, *LI);
+
+ // L is now a subloop of our outer loop.
+ NewOuter->addChildLoop(L);
+
+ for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i)
+ NewOuter->addBlockEntry(L->getBlocks()[i]);
+
+ // Determine which blocks should stay in L and which should be moved out to
+ // the Outer loop now.
+ std::set<BasicBlock*> BlocksInL;
+ for (pred_iterator PI = pred_begin(Header), E = pred_end(Header); PI!=E; ++PI)
+ if (DT->dominates(Header, *PI))
+ AddBlockAndPredsToSet(*PI, Header, BlocksInL);
+
+
+ // Scan all of the loop children of L, moving them to OuterLoop if they are
+ // not part of the inner loop.
+ const std::vector<Loop*> &SubLoops = L->getSubLoops();
+ for (size_t I = 0; I != SubLoops.size(); )
+ if (BlocksInL.count(SubLoops[I]->getHeader()))
+ ++I; // Loop remains in L
+ else
+ NewOuter->addChildLoop(L->removeChildLoop(SubLoops.begin() + I));
+
+ // Now that we know which blocks are in L and which need to be moved to
+ // OuterLoop, move any blocks that need it.
+ for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
+ BasicBlock *BB = L->getBlocks()[i];
+ if (!BlocksInL.count(BB)) {
+ // Move this block to the parent, updating the exit blocks sets
+ L->removeBlockFromLoop(BB);
+ if ((*LI)[BB] == L)
+ LI->changeLoopFor(BB, NewOuter);
+ --i;
+ }
+ }
+
+ return NewOuter;
+}
+
+
+
+/// InsertUniqueBackedgeBlock - This method is called when the specified loop
+/// has more than one backedge in it. If this occurs, revector all of these
+/// backedges to target a new basic block and have that block branch to the loop
+/// header. This ensures that loops have exactly one backedge.
+///
+void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L) {
+ assert(L->getNumBackEdges() > 1 && "Must have > 1 backedge!");
+
+ // Get information about the loop
+ BasicBlock *Preheader = L->getLoopPreheader();
+ BasicBlock *Header = L->getHeader();
+ Function *F = Header->getParent();
+
+ // Figure out which basic blocks contain back-edges to the loop header.
+ std::vector<BasicBlock*> BackedgeBlocks;
+ for (pred_iterator I = pred_begin(Header), E = pred_end(Header); I != E; ++I)
+ if (*I != Preheader) BackedgeBlocks.push_back(*I);
+
+ // Create and insert the new backedge block...
+ BasicBlock *BEBlock = new BasicBlock(Header->getName()+".backedge", F);
+ BranchInst *BETerminator = new BranchInst(Header, BEBlock);
+
+ // Move the new backedge block to right after the last backedge block.
+ Function::iterator InsertPos = BackedgeBlocks.back(); ++InsertPos;
+ F->getBasicBlockList().splice(InsertPos, F->getBasicBlockList(), BEBlock);
+
+ // Now that the block has been inserted into the function, create PHI nodes in
+ // the backedge block which correspond to any PHI nodes in the header block.
+ for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ PHINode *NewPN = new PHINode(PN->getType(), PN->getName()+".be",
+ BETerminator);
+ NewPN->reserveOperandSpace(BackedgeBlocks.size());
+ if (AA) AA->copyValue(PN, NewPN);
+
+ // Loop over the PHI node, moving all entries except the one for the
+ // preheader over to the new PHI node.
+ unsigned PreheaderIdx = ~0U;
+ bool HasUniqueIncomingValue = true;
+ Value *UniqueValue = 0;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *IBB = PN->getIncomingBlock(i);
+ Value *IV = PN->getIncomingValue(i);
+ if (IBB == Preheader) {
+ PreheaderIdx = i;
+ } else {
+ NewPN->addIncoming(IV, IBB);
+ if (HasUniqueIncomingValue) {
+ if (UniqueValue == 0)
+ UniqueValue = IV;
+ else if (UniqueValue != IV)
+ HasUniqueIncomingValue = false;
+ }
+ }
+ }
+
+ // Delete all of the incoming values from the old PN except the preheader's
+ assert(PreheaderIdx != ~0U && "PHI has no preheader entry??");
+ if (PreheaderIdx != 0) {
+ PN->setIncomingValue(0, PN->getIncomingValue(PreheaderIdx));
+ PN->setIncomingBlock(0, PN->getIncomingBlock(PreheaderIdx));
+ }
+ // Nuke all entries except the zero'th.
+ for (unsigned i = 0, e = PN->getNumIncomingValues()-1; i != e; ++i)
+ PN->removeIncomingValue(e-i, false);
+
+ // Finally, add the newly constructed PHI node as the entry for the BEBlock.
+ PN->addIncoming(NewPN, BEBlock);
+
+ // As an optimization, if all incoming values in the new PhiNode (which is a
+ // subset of the incoming values of the old PHI node) have the same value,
+ // eliminate the PHI Node.
+ if (HasUniqueIncomingValue) {
+ NewPN->replaceAllUsesWith(UniqueValue);
+ if (AA) AA->deleteValue(NewPN);
+ BEBlock->getInstList().erase(NewPN);
+ }
+ }
+
+ // Now that all of the PHI nodes have been inserted and adjusted, modify the
+ // backedge blocks to just to the BEBlock instead of the header.
+ for (unsigned i = 0, e = BackedgeBlocks.size(); i != e; ++i) {
+ TerminatorInst *TI = BackedgeBlocks[i]->getTerminator();
+ for (unsigned Op = 0, e = TI->getNumSuccessors(); Op != e; ++Op)
+ if (TI->getSuccessor(Op) == Header)
+ TI->setSuccessor(Op, BEBlock);
+ }
+
+ //===--- Update all analyses which we must preserve now -----------------===//
+
+ // Update Loop Information - we know that this block is now in the current
+ // loop and all parent loops.
+ L->addBasicBlockToLoop(BEBlock, *LI);
+
+ // Update dominator information
+ DT->splitBlock(BEBlock);
+ if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>())
+ DF->splitBlock(BEBlock);
+}
+
+
diff --git a/lib/Transforms/Utils/LowerAllocations.cpp b/lib/Transforms/Utils/LowerAllocations.cpp
new file mode 100644
index 0000000..7ce2479
--- /dev/null
+++ b/lib/Transforms/Utils/LowerAllocations.cpp
@@ -0,0 +1,176 @@
+//===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The LowerAllocations transformation is a target-dependent tranformation
+// because it depends on the size of data types and alignment constraints.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lowerallocs"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Module.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Constants.h"
+#include "llvm/Pass.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+STATISTIC(NumLowered, "Number of allocations lowered");
+
+namespace {
+ /// LowerAllocations - Turn malloc and free instructions into %malloc and
+ /// %free calls.
+ ///
+ class VISIBILITY_HIDDEN LowerAllocations : public BasicBlockPass {
+ Constant *MallocFunc; // Functions in the module we are processing
+ Constant *FreeFunc; // Initialized by doInitialization
+ bool LowerMallocArgToInteger;
+ public:
+ static char ID; // Pass ID, replacement for typeid
+ LowerAllocations(bool LowerToInt = false)
+ : BasicBlockPass((intptr_t)&ID), MallocFunc(0), FreeFunc(0),
+ LowerMallocArgToInteger(LowerToInt) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>();
+ AU.setPreservesCFG();
+
+ // This is a cluster of orthogonal Transforms:
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ }
+
+ /// doPassInitialization - For the lower allocations pass, this ensures that
+ /// a module contains a declaration for a malloc and a free function.
+ ///
+ bool doInitialization(Module &M);
+
+ virtual bool doInitialization(Function &F) {
+ return BasicBlockPass::doInitialization(F);
+ }
+
+ /// runOnBasicBlock - This method does the actual work of converting
+ /// instructions over, assuming that the pass has already been initialized.
+ ///
+ bool runOnBasicBlock(BasicBlock &BB);
+ };
+
+ char LowerAllocations::ID = 0;
+ RegisterPass<LowerAllocations>
+ X("lowerallocs", "Lower allocations from instructions to calls");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LowerAllocationsID = X.getPassInfo();
+// createLowerAllocationsPass - Interface to this file...
+Pass *llvm::createLowerAllocationsPass(bool LowerMallocArgToInteger) {
+ return new LowerAllocations(LowerMallocArgToInteger);
+}
+
+
+// doInitialization - For the lower allocations pass, this ensures that a
+// module contains a declaration for a malloc and a free function.
+//
+// This function is always successful.
+//
+bool LowerAllocations::doInitialization(Module &M) {
+ const Type *BPTy = PointerType::get(Type::Int8Ty);
+ // Prototype malloc as "char* malloc(...)", because we don't know in
+ // doInitialization whether size_t is int or long.
+ FunctionType *FT = FunctionType::get(BPTy, std::vector<const Type*>(), true);
+ MallocFunc = M.getOrInsertFunction("malloc", FT);
+ FreeFunc = M.getOrInsertFunction("free" , Type::VoidTy, BPTy, (Type *)0);
+ return true;
+}
+
+// runOnBasicBlock - This method does the actual work of converting
+// instructions over, assuming that the pass has already been initialized.
+//
+bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
+ bool Changed = false;
+ assert(MallocFunc && FreeFunc && "Pass not initialized!");
+
+ BasicBlock::InstListType &BBIL = BB.getInstList();
+
+ const TargetData &TD = getAnalysis<TargetData>();
+ const Type *IntPtrTy = TD.getIntPtrType();
+
+ // Loop over all of the instructions, looking for malloc or free instructions
+ for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
+ if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
+ const Type *AllocTy = MI->getType()->getElementType();
+
+ // malloc(type) becomes sbyte *malloc(size)
+ Value *MallocArg;
+ if (LowerMallocArgToInteger)
+ MallocArg = ConstantInt::get(Type::Int64Ty, TD.getTypeSize(AllocTy));
+ else
+ MallocArg = ConstantExpr::getSizeOf(AllocTy);
+ MallocArg = ConstantExpr::getTruncOrBitCast(cast<Constant>(MallocArg),
+ IntPtrTy);
+
+ if (MI->isArrayAllocation()) {
+ if (isa<ConstantInt>(MallocArg) &&
+ cast<ConstantInt>(MallocArg)->isOne()) {
+ MallocArg = MI->getOperand(0); // Operand * 1 = Operand
+ } else if (Constant *CO = dyn_cast<Constant>(MI->getOperand(0))) {
+ CO = ConstantExpr::getIntegerCast(CO, IntPtrTy, false /*ZExt*/);
+ MallocArg = ConstantExpr::getMul(CO, cast<Constant>(MallocArg));
+ } else {
+ Value *Scale = MI->getOperand(0);
+ if (Scale->getType() != IntPtrTy)
+ Scale = CastInst::createIntegerCast(Scale, IntPtrTy, false /*ZExt*/,
+ "", I);
+
+ // Multiply it by the array size if necessary...
+ MallocArg = BinaryOperator::create(Instruction::Mul, Scale,
+ MallocArg, "", I);
+ }
+ }
+
+ // Create the call to Malloc.
+ CallInst *MCall = new CallInst(MallocFunc, MallocArg, "", I);
+ MCall->setTailCall();
+
+ // Create a cast instruction to convert to the right type...
+ Value *MCast;
+ if (MCall->getType() != Type::VoidTy)
+ MCast = new BitCastInst(MCall, MI->getType(), "", I);
+ else
+ MCast = Constant::getNullValue(MI->getType());
+
+ // Replace all uses of the old malloc inst with the cast inst
+ MI->replaceAllUsesWith(MCast);
+ I = --BBIL.erase(I); // remove and delete the malloc instr...
+ Changed = true;
+ ++NumLowered;
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(I)) {
+ Value *PtrCast = new BitCastInst(FI->getOperand(0),
+ PointerType::get(Type::Int8Ty), "", I);
+
+ // Insert a call to the free function...
+ (new CallInst(FreeFunc, PtrCast, "", I))->setTailCall();
+
+ // Delete the old free instruction
+ I = --BBIL.erase(I);
+ Changed = true;
+ ++NumLowered;
+ }
+ }
+
+ return Changed;
+}
+
diff --git a/lib/Transforms/Utils/LowerInvoke.cpp b/lib/Transforms/Utils/LowerInvoke.cpp
new file mode 100644
index 0000000..d72c018
--- /dev/null
+++ b/lib/Transforms/Utils/LowerInvoke.cpp
@@ -0,0 +1,585 @@
+//===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This transformation is designed for use by code generators which do not yet
+// support stack unwinding. This pass supports two models of exception handling
+// lowering, the 'cheap' support and the 'expensive' support.
+//
+// 'Cheap' exception handling support gives the program the ability to execute
+// any program which does not "throw an exception", by turning 'invoke'
+// instructions into calls and by turning 'unwind' instructions into calls to
+// abort(). If the program does dynamically use the unwind instruction, the
+// program will print a message then abort.
+//
+// 'Expensive' exception handling support gives the full exception handling
+// support to the program at the cost of making the 'invoke' instruction
+// really expensive. It basically inserts setjmp/longjmp calls to emulate the
+// exception handling as necessary.
+//
+// Because the 'expensive' support slows down programs a lot, and EH is only
+// used for a subset of the programs, it must be specifically enabled by an
+// option.
+//
+// Note that after this pass runs the CFG is not entirely accurate (exceptional
+// control flow edges are not correct anymore) so only very simple things should
+// be done after the lowerinvoke pass has run (like generation of native code).
+// This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
+// support the invoke instruction yet" lowering pass.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lowerinvoke"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Target/TargetLowering.h"
+#include <csetjmp>
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumInvokes, "Number of invokes replaced");
+STATISTIC(NumUnwinds, "Number of unwinds replaced");
+STATISTIC(NumSpilled, "Number of registers live across unwind edges");
+
+static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
+ cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
+
+namespace {
+ class VISIBILITY_HIDDEN LowerInvoke : public FunctionPass {
+ // Used for both models.
+ Constant *WriteFn;
+ Constant *AbortFn;
+ Value *AbortMessage;
+ unsigned AbortMessageLength;
+
+ // Used for expensive EH support.
+ const Type *JBLinkTy;
+ GlobalVariable *JBListHead;
+ Constant *SetJmpFn, *LongJmpFn;
+
+ // We peek in TLI to grab the target's jmp_buf size and alignment
+ const TargetLowering *TLI;
+
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ LowerInvoke(const TargetLowering *tli = NULL) : FunctionPass((intptr_t)&ID),
+ TLI(tli) { }
+ bool doInitialization(Module &M);
+ bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // This is a cluster of orthogonal Transforms
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+
+ private:
+ void createAbortMessage(Module *M);
+ void writeAbortMessage(Instruction *IB);
+ bool insertCheapEHSupport(Function &F);
+ void splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes);
+ void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
+ AllocaInst *InvokeNum, SwitchInst *CatchSwitch);
+ bool insertExpensiveEHSupport(Function &F);
+ };
+
+ char LowerInvoke::ID = 0;
+ RegisterPass<LowerInvoke>
+ X("lowerinvoke", "Lower invoke and unwind, for unwindless code generators");
+}
+
+const PassInfo *llvm::LowerInvokePassID = X.getPassInfo();
+
+// Public Interface To the LowerInvoke pass.
+FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
+ return new LowerInvoke(TLI);
+}
+
+// doInitialization - Make sure that there is a prototype for abort in the
+// current module.
+bool LowerInvoke::doInitialization(Module &M) {
+ const Type *VoidPtrTy = PointerType::get(Type::Int8Ty);
+ AbortMessage = 0;
+ if (ExpensiveEHSupport) {
+ // Insert a type for the linked list of jump buffers.
+ unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
+ JBSize = JBSize ? JBSize : 200;
+ const Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
+
+ { // The type is recursive, so use a type holder.
+ std::vector<const Type*> Elements;
+ Elements.push_back(JmpBufTy);
+ OpaqueType *OT = OpaqueType::get();
+ Elements.push_back(PointerType::get(OT));
+ PATypeHolder JBLType(StructType::get(Elements));
+ OT->refineAbstractTypeTo(JBLType.get()); // Complete the cycle.
+ JBLinkTy = JBLType.get();
+ M.addTypeName("llvm.sjljeh.jmpbufty", JBLinkTy);
+ }
+
+ const Type *PtrJBList = PointerType::get(JBLinkTy);
+
+ // Now that we've done that, insert the jmpbuf list head global, unless it
+ // already exists.
+ if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
+ JBListHead = new GlobalVariable(PtrJBList, false,
+ GlobalValue::LinkOnceLinkage,
+ Constant::getNullValue(PtrJBList),
+ "llvm.sjljeh.jblist", &M);
+ }
+ SetJmpFn = M.getOrInsertFunction("llvm.setjmp", Type::Int32Ty,
+ PointerType::get(JmpBufTy), (Type *)0);
+ LongJmpFn = M.getOrInsertFunction("llvm.longjmp", Type::VoidTy,
+ PointerType::get(JmpBufTy),
+ Type::Int32Ty, (Type *)0);
+ }
+
+ // We need the 'write' and 'abort' functions for both models.
+ AbortFn = M.getOrInsertFunction("abort", Type::VoidTy, (Type *)0);
+#if 0 // "write" is Unix-specific.. code is going away soon anyway.
+ WriteFn = M.getOrInsertFunction("write", Type::VoidTy, Type::Int32Ty,
+ VoidPtrTy, Type::Int32Ty, (Type *)0);
+#else
+ WriteFn = 0;
+#endif
+ return true;
+}
+
+void LowerInvoke::createAbortMessage(Module *M) {
+ if (ExpensiveEHSupport) {
+ // The abort message for expensive EH support tells the user that the
+ // program 'unwound' without an 'invoke' instruction.
+ Constant *Msg =
+ ConstantArray::get("ERROR: Exception thrown, but not caught!\n");
+ AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
+
+ GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
+ GlobalValue::InternalLinkage,
+ Msg, "abortmsg", M);
+ std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
+ AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
+ } else {
+ // The abort message for cheap EH support tells the user that EH is not
+ // enabled.
+ Constant *Msg =
+ ConstantArray::get("Exception handler needed, but not enabled. Recompile"
+ " program with -enable-correct-eh-support.\n");
+ AbortMessageLength = Msg->getNumOperands()-1; // don't include \0
+
+ GlobalVariable *MsgGV = new GlobalVariable(Msg->getType(), true,
+ GlobalValue::InternalLinkage,
+ Msg, "abortmsg", M);
+ std::vector<Constant*> GEPIdx(2, Constant::getNullValue(Type::Int32Ty));
+ AbortMessage = ConstantExpr::getGetElementPtr(MsgGV, &GEPIdx[0], 2);
+ }
+}
+
+
+void LowerInvoke::writeAbortMessage(Instruction *IB) {
+#if 0
+ if (AbortMessage == 0)
+ createAbortMessage(IB->getParent()->getParent()->getParent());
+
+ // These are the arguments we WANT...
+ Value* Args[3];
+ Args[0] = ConstantInt::get(Type::Int32Ty, 2);
+ Args[1] = AbortMessage;
+ Args[2] = ConstantInt::get(Type::Int32Ty, AbortMessageLength);
+ (new CallInst(WriteFn, Args, 3, "", IB))->setTailCall();
+#endif
+}
+
+bool LowerInvoke::insertCheapEHSupport(Function &F) {
+ bool Changed = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
+ // Insert a normal call instruction...
+ CallInst *NewCall = new CallInst(II->getCalledValue(),
+ &CallArgs[0], CallArgs.size(), "", II);
+ NewCall->takeName(II);
+ NewCall->setCallingConv(II->getCallingConv());
+ II->replaceAllUsesWith(NewCall);
+
+ // Insert an unconditional branch to the normal destination.
+ new BranchInst(II->getNormalDest(), II);
+
+ // Remove any PHI node entries from the exception destination.
+ II->getUnwindDest()->removePredecessor(BB);
+
+ // Remove the invoke instruction now.
+ BB->getInstList().erase(II);
+
+ ++NumInvokes; Changed = true;
+ } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
+ // Insert a new call to write(2, AbortMessage, AbortMessageLength);
+ writeAbortMessage(UI);
+
+ // Insert a call to abort()
+ (new CallInst(AbortFn, "", UI))->setTailCall();
+
+ // Insert a return instruction. This really should be a "barrier", as it
+ // is unreachable.
+ new ReturnInst(F.getReturnType() == Type::VoidTy ? 0 :
+ Constant::getNullValue(F.getReturnType()), UI);
+
+ // Remove the unwind instruction now.
+ BB->getInstList().erase(UI);
+
+ ++NumUnwinds; Changed = true;
+ }
+ return Changed;
+}
+
+/// rewriteExpensiveInvoke - Insert code and hack the function to replace the
+/// specified invoke instruction with a call.
+void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
+ AllocaInst *InvokeNum,
+ SwitchInst *CatchSwitch) {
+ ConstantInt *InvokeNoC = ConstantInt::get(Type::Int32Ty, InvokeNo);
+
+ // Insert a store of the invoke num before the invoke and store zero into the
+ // location afterward.
+ new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
+
+ BasicBlock::iterator NI = II->getNormalDest()->begin();
+ while (isa<PHINode>(NI)) ++NI;
+ // nonvolatile.
+ new StoreInst(Constant::getNullValue(Type::Int32Ty), InvokeNum, false, NI);
+
+ // Add a switch case to our unwind block.
+ CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
+
+ // Insert a normal call instruction.
+ std::vector<Value*> CallArgs(II->op_begin()+3, II->op_end());
+ CallInst *NewCall = new CallInst(II->getCalledValue(),
+ &CallArgs[0], CallArgs.size(), "",
+ II);
+ NewCall->takeName(II);
+ NewCall->setCallingConv(II->getCallingConv());
+ II->replaceAllUsesWith(NewCall);
+
+ // Replace the invoke with an uncond branch.
+ new BranchInst(II->getNormalDest(), NewCall->getParent());
+ II->eraseFromParent();
+}
+
+/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
+/// we reach blocks we've already seen.
+static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
+ if (!LiveBBs.insert(BB).second) return; // already been here.
+
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ MarkBlocksLiveIn(*PI, LiveBBs);
+}
+
+// First thing we need to do is scan the whole function for values that are
+// live across unwind edges. Each value that is live across an unwind edge
+// we spill into a stack location, guaranteeing that there is nothing live
+// across the unwind edge. This process also splits all critical edges
+// coming out of invoke's.
+void LowerInvoke::
+splitLiveRangesLiveAcrossInvokes(std::vector<InvokeInst*> &Invokes) {
+ // First step, split all critical edges from invoke instructions.
+ for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
+ InvokeInst *II = Invokes[i];
+ SplitCriticalEdge(II, 0, this);
+ SplitCriticalEdge(II, 1, this);
+ assert(!isa<PHINode>(II->getNormalDest()) &&
+ !isa<PHINode>(II->getUnwindDest()) &&
+ "critical edge splitting left single entry phi nodes?");
+ }
+
+ Function *F = Invokes.back()->getParent()->getParent();
+
+ // To avoid having to handle incoming arguments specially, we lower each arg
+ // to a copy instruction in the entry block. This ensures that the argument
+ // value itself cannot be live across the entry block.
+ BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
+ while (isa<AllocaInst>(AfterAllocaInsertPt) &&
+ isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
+ ++AfterAllocaInsertPt;
+ for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
+ AI != E; ++AI) {
+ // This is always a no-op cast because we're casting AI to AI->getType() so
+ // src and destination types are identical. BitCast is the only possibility.
+ CastInst *NC = new BitCastInst(
+ AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
+ AI->replaceAllUsesWith(NC);
+ // Normally its is forbidden to replace a CastInst's operand because it
+ // could cause the opcode to reflect an illegal conversion. However, we're
+ // replacing it here with the same value it was constructed with to simply
+ // make NC its user.
+ NC->setOperand(0, AI);
+ }
+
+ // Finally, scan the code looking for instructions with bad live ranges.
+ for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
+ for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
+ // Ignore obvious cases we don't have to handle. In particular, most
+ // instructions either have no uses or only have a single use inside the
+ // current block. Ignore them quickly.
+ Instruction *Inst = II;
+ if (Inst->use_empty()) continue;
+ if (Inst->hasOneUse() &&
+ cast<Instruction>(Inst->use_back())->getParent() == BB &&
+ !isa<PHINode>(Inst->use_back())) continue;
+
+ // If this is an alloca in the entry block, it's not a real register
+ // value.
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
+ if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
+ continue;
+
+ // Avoid iterator invalidation by copying users to a temporary vector.
+ std::vector<Instruction*> Users;
+ for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
+ UI != E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (User->getParent() != BB || isa<PHINode>(User))
+ Users.push_back(User);
+ }
+
+ // Scan all of the uses and see if the live range is live across an unwind
+ // edge. If we find a use live across an invoke edge, create an alloca
+ // and spill the value.
+ std::set<InvokeInst*> InvokesWithStoreInserted;
+
+ // Find all of the blocks that this value is live in.
+ std::set<BasicBlock*> LiveBBs;
+ LiveBBs.insert(Inst->getParent());
+ while (!Users.empty()) {
+ Instruction *U = Users.back();
+ Users.pop_back();
+
+ if (!isa<PHINode>(U)) {
+ MarkBlocksLiveIn(U->getParent(), LiveBBs);
+ } else {
+ // Uses for a PHI node occur in their predecessor block.
+ PHINode *PN = cast<PHINode>(U);
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (PN->getIncomingValue(i) == Inst)
+ MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
+ }
+ }
+
+ // Now that we know all of the blocks that this thing is live in, see if
+ // it includes any of the unwind locations.
+ bool NeedsSpill = false;
+ for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
+ BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
+ if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
+ NeedsSpill = true;
+ }
+ }
+
+ // If we decided we need a spill, do it.
+ if (NeedsSpill) {
+ ++NumSpilled;
+ DemoteRegToStack(*Inst, true);
+ }
+ }
+}
+
+bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
+ std::vector<ReturnInst*> Returns;
+ std::vector<UnwindInst*> Unwinds;
+ std::vector<InvokeInst*> Invokes;
+
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
+ // Remember all return instructions in case we insert an invoke into this
+ // function.
+ Returns.push_back(RI);
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ Invokes.push_back(II);
+ } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
+ Unwinds.push_back(UI);
+ }
+
+ if (Unwinds.empty() && Invokes.empty()) return false;
+
+ NumInvokes += Invokes.size();
+ NumUnwinds += Unwinds.size();
+
+ // TODO: This is not an optimal way to do this. In particular, this always
+ // inserts setjmp calls into the entries of functions with invoke instructions
+ // even though there are possibly paths through the function that do not
+ // execute any invokes. In particular, for functions with early exits, e.g.
+ // the 'addMove' method in hexxagon, it would be nice to not have to do the
+ // setjmp stuff on the early exit path. This requires a bit of dataflow, but
+ // would not be too hard to do.
+
+ // If we have an invoke instruction, insert a setjmp that dominates all
+ // invokes. After the setjmp, use a cond branch that goes to the original
+ // code path on zero, and to a designated 'catch' block of nonzero.
+ Value *OldJmpBufPtr = 0;
+ if (!Invokes.empty()) {
+ // First thing we need to do is scan the whole function for values that are
+ // live across unwind edges. Each value that is live across an unwind edge
+ // we spill into a stack location, guaranteeing that there is nothing live
+ // across the unwind edge. This process also splits all critical edges
+ // coming out of invoke's.
+ splitLiveRangesLiveAcrossInvokes(Invokes);
+
+ BasicBlock *EntryBB = F.begin();
+
+ // Create an alloca for the incoming jump buffer ptr and the new jump buffer
+ // that needs to be restored on all exits from the function. This is an
+ // alloca because the value needs to be live across invokes.
+ unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
+ AllocaInst *JmpBuf =
+ new AllocaInst(JBLinkTy, 0, Align, "jblink", F.begin()->begin());
+
+ std::vector<Value*> Idx;
+ Idx.push_back(Constant::getNullValue(Type::Int32Ty));
+ Idx.push_back(ConstantInt::get(Type::Int32Ty, 1));
+ OldJmpBufPtr = new GetElementPtrInst(JmpBuf, &Idx[0], 2, "OldBuf",
+ EntryBB->getTerminator());
+
+ // Copy the JBListHead to the alloca.
+ Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
+ EntryBB->getTerminator());
+ new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
+
+ // Add the new jumpbuf to the list.
+ new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
+
+ // Create the catch block. The catch block is basically a big switch
+ // statement that goes to all of the invoke catch blocks.
+ BasicBlock *CatchBB = new BasicBlock("setjmp.catch", &F);
+
+ // Create an alloca which keeps track of which invoke is currently
+ // executing. For normal calls it contains zero.
+ AllocaInst *InvokeNum = new AllocaInst(Type::Int32Ty, 0, "invokenum",
+ EntryBB->begin());
+ new StoreInst(ConstantInt::get(Type::Int32Ty, 0), InvokeNum, true,
+ EntryBB->getTerminator());
+
+ // Insert a load in the Catch block, and a switch on its value. By default,
+ // we go to a block that just does an unwind (which is the correct action
+ // for a standard call).
+ BasicBlock *UnwindBB = new BasicBlock("unwindbb", &F);
+ Unwinds.push_back(new UnwindInst(UnwindBB));
+
+ Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
+ SwitchInst *CatchSwitch =
+ new SwitchInst(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
+
+ // Now that things are set up, insert the setjmp call itself.
+
+ // Split the entry block to insert the conditional branch for the setjmp.
+ BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
+ "setjmp.cont");
+
+ Idx[1] = ConstantInt::get(Type::Int32Ty, 0);
+ Value *JmpBufPtr = new GetElementPtrInst(JmpBuf, &Idx[0], Idx.size(),
+ "TheJmpBuf",
+ EntryBB->getTerminator());
+ Value *SJRet = new CallInst(SetJmpFn, JmpBufPtr, "sjret",
+ EntryBB->getTerminator());
+
+ // Compare the return value to zero.
+ Value *IsNormal = new ICmpInst(ICmpInst::ICMP_EQ, SJRet,
+ Constant::getNullValue(SJRet->getType()),
+ "notunwind", EntryBB->getTerminator());
+ // Nuke the uncond branch.
+ EntryBB->getTerminator()->eraseFromParent();
+
+ // Put in a new condbranch in its place.
+ new BranchInst(ContBlock, CatchBB, IsNormal, EntryBB);
+
+ // At this point, we are all set up, rewrite each invoke instruction.
+ for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
+ rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, CatchSwitch);
+ }
+
+ // We know that there is at least one unwind.
+
+ // Create three new blocks, the block to load the jmpbuf ptr and compare
+ // against null, the block to do the longjmp, and the error block for if it
+ // is null. Add them at the end of the function because they are not hot.
+ BasicBlock *UnwindHandler = new BasicBlock("dounwind", &F);
+ BasicBlock *UnwindBlock = new BasicBlock("unwind", &F);
+ BasicBlock *TermBlock = new BasicBlock("unwinderror", &F);
+
+ // If this function contains an invoke, restore the old jumpbuf ptr.
+ Value *BufPtr;
+ if (OldJmpBufPtr) {
+ // Before the return, insert a copy from the saved value to the new value.
+ BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
+ new StoreInst(BufPtr, JBListHead, UnwindHandler);
+ } else {
+ BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
+ }
+
+ // Load the JBList, if it's null, then there was no catch!
+ Value *NotNull = new ICmpInst(ICmpInst::ICMP_NE, BufPtr,
+ Constant::getNullValue(BufPtr->getType()),
+ "notnull", UnwindHandler);
+ new BranchInst(UnwindBlock, TermBlock, NotNull, UnwindHandler);
+
+ // Create the block to do the longjmp.
+ // Get a pointer to the jmpbuf and longjmp.
+ std::vector<Value*> Idx;
+ Idx.push_back(Constant::getNullValue(Type::Int32Ty));
+ Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
+ Idx[0] = new GetElementPtrInst(BufPtr, &Idx[0], 2, "JmpBuf", UnwindBlock);
+ Idx[1] = ConstantInt::get(Type::Int32Ty, 1);
+ new CallInst(LongJmpFn, &Idx[0], Idx.size(), "", UnwindBlock);
+ new UnreachableInst(UnwindBlock);
+
+ // Set up the term block ("throw without a catch").
+ new UnreachableInst(TermBlock);
+
+ // Insert a new call to write(2, AbortMessage, AbortMessageLength);
+ writeAbortMessage(TermBlock->getTerminator());
+
+ // Insert a call to abort()
+ (new CallInst(AbortFn, "",
+ TermBlock->getTerminator()))->setTailCall();
+
+
+ // Replace all unwinds with a branch to the unwind handler.
+ for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
+ new BranchInst(UnwindHandler, Unwinds[i]);
+ Unwinds[i]->eraseFromParent();
+ }
+
+ // Finally, for any returns from this function, if this function contains an
+ // invoke, restore the old jmpbuf pointer to its input value.
+ if (OldJmpBufPtr) {
+ for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
+ ReturnInst *R = Returns[i];
+
+ // Before the return, insert a copy from the saved value to the new value.
+ Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
+ new StoreInst(OldBuf, JBListHead, true, R);
+ }
+ }
+
+ return true;
+}
+
+bool LowerInvoke::runOnFunction(Function &F) {
+ if (ExpensiveEHSupport)
+ return insertExpensiveEHSupport(F);
+ else
+ return insertCheapEHSupport(F);
+}
diff --git a/lib/Transforms/Utils/LowerSelect.cpp b/lib/Transforms/Utils/LowerSelect.cpp
new file mode 100644
index 0000000..1882695
--- /dev/null
+++ b/lib/Transforms/Utils/LowerSelect.cpp
@@ -0,0 +1,105 @@
+//===- LowerSelect.cpp - Transform select insts to branches ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers select instructions into conditional branches for targets
+// that do not have conditional moves or that have not implemented the select
+// instruction yet.
+//
+// Note that this pass could be improved. In particular it turns every select
+// instruction into a new conditional branch, even though some common cases have
+// select instructions on the same predicate next to each other. It would be
+// better to use the same branch for the whole group of selects.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Type.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+namespace {
+ /// LowerSelect - Turn select instructions into conditional branches.
+ ///
+ class VISIBILITY_HIDDEN LowerSelect : public FunctionPass {
+ bool OnlyFP; // Only lower FP select instructions?
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ LowerSelect(bool onlyfp = false) : FunctionPass((intptr_t)&ID),
+ OnlyFP(onlyfp) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // This certainly destroys the CFG.
+ // This is a cluster of orthogonal Transforms:
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+
+ bool runOnFunction(Function &F);
+ };
+
+ char LowerSelect::ID = 0;
+ RegisterPass<LowerSelect>
+ X("lowerselect", "Lower select instructions to branches");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LowerSelectID = X.getPassInfo();
+//===----------------------------------------------------------------------===//
+// This pass converts SelectInst instructions into conditional branch and PHI
+// instructions. If the OnlyFP flag is set to true, then only floating point
+// select instructions are lowered.
+//
+FunctionPass *llvm::createLowerSelectPass(bool OnlyFP) {
+ return new LowerSelect(OnlyFP);
+}
+
+
+bool LowerSelect::runOnFunction(Function &F) {
+ bool Changed = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ if (SelectInst *SI = dyn_cast<SelectInst>(I))
+ if (!OnlyFP || SI->getType()->isFloatingPoint()) {
+ // Split this basic block in half right before the select instruction.
+ BasicBlock *NewCont =
+ BB->splitBasicBlock(I, BB->getName()+".selectcont");
+
+ // Make the true block, and make it branch to the continue block.
+ BasicBlock *NewTrue = new BasicBlock(BB->getName()+".selecttrue",
+ BB->getParent(), NewCont);
+ new BranchInst(NewCont, NewTrue);
+
+ // Make the unconditional branch in the incoming block be a
+ // conditional branch on the select predicate.
+ BB->getInstList().erase(BB->getTerminator());
+ new BranchInst(NewTrue, NewCont, SI->getCondition(), BB);
+
+ // Create a new PHI node in the cont block with the entries we need.
+ PHINode *PN = new PHINode(SI->getType(), "", NewCont->begin());
+ PN->takeName(SI);
+ PN->addIncoming(SI->getTrueValue(), NewTrue);
+ PN->addIncoming(SI->getFalseValue(), BB);
+
+ // Use the PHI instead of the select.
+ SI->replaceAllUsesWith(PN);
+ NewCont->getInstList().erase(SI);
+
+ Changed = true;
+ break; // This block is done with.
+ }
+ }
+ return Changed;
+}
diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp
new file mode 100644
index 0000000..633633d
--- /dev/null
+++ b/lib/Transforms/Utils/LowerSwitch.cpp
@@ -0,0 +1,324 @@
+//===- LowerSwitch.cpp - Eliminate Switch instructions --------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The LowerSwitch transformation rewrites switch statements with a sequence of
+// branches, which allows targets to get away with not implementing the switch
+// statement until it is convenient.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Constants.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include <algorithm>
+using namespace llvm;
+
+namespace {
+ /// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch
+ /// instructions. Note that this cannot be a BasicBlock pass because it
+ /// modifies the CFG!
+ class VISIBILITY_HIDDEN LowerSwitch : public FunctionPass {
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ LowerSwitch() : FunctionPass((intptr_t) &ID) {}
+
+ virtual bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // This is a cluster of orthogonal Transforms
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerInvokePassID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+
+ struct CaseRange {
+ Constant* Low;
+ Constant* High;
+ BasicBlock* BB;
+
+ CaseRange() : Low(0), High(0), BB(0) { }
+ CaseRange(Constant* low, Constant* high, BasicBlock* bb) :
+ Low(low), High(high), BB(bb) { }
+ };
+
+ typedef std::vector<CaseRange> CaseVector;
+ typedef std::vector<CaseRange>::iterator CaseItr;
+ private:
+ void processSwitchInst(SwitchInst *SI);
+
+ BasicBlock* switchConvert(CaseItr Begin, CaseItr End, Value* Val,
+ BasicBlock* OrigBlock, BasicBlock* Default);
+ BasicBlock* newLeafBlock(CaseRange& Leaf, Value* Val,
+ BasicBlock* OrigBlock, BasicBlock* Default);
+ unsigned Clusterify(CaseVector& Cases, SwitchInst *SI);
+ };
+
+ /// The comparison function for sorting the switch case values in the vector.
+ /// WARNING: Case ranges should be disjoint!
+ struct CaseCmp {
+ bool operator () (const LowerSwitch::CaseRange& C1,
+ const LowerSwitch::CaseRange& C2) {
+
+ const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
+ const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
+ return CI1->getValue().slt(CI2->getValue());
+ }
+ };
+
+ char LowerSwitch::ID = 0;
+ RegisterPass<LowerSwitch>
+ X("lowerswitch", "Lower SwitchInst's to branches");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LowerSwitchID = X.getPassInfo();
+// createLowerSwitchPass - Interface to this file...
+FunctionPass *llvm::createLowerSwitchPass() {
+ return new LowerSwitch();
+}
+
+bool LowerSwitch::runOnFunction(Function &F) {
+ bool Changed = false;
+
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
+ BasicBlock *Cur = I++; // Advance over block so we don't traverse new blocks
+
+ if (SwitchInst *SI = dyn_cast<SwitchInst>(Cur->getTerminator())) {
+ Changed = true;
+ processSwitchInst(SI);
+ }
+ }
+
+ return Changed;
+}
+
+// operator<< - Used for debugging purposes.
+//
+static std::ostream& operator<<(std::ostream &O,
+ const LowerSwitch::CaseVector &C) {
+ O << "[";
+
+ for (LowerSwitch::CaseVector::const_iterator B = C.begin(),
+ E = C.end(); B != E; ) {
+ O << *B->Low << " -" << *B->High;
+ if (++B != E) O << ", ";
+ }
+
+ return O << "]";
+}
+
+static OStream& operator<<(OStream &O, const LowerSwitch::CaseVector &C) {
+ if (O.stream()) *O.stream() << C;
+ return O;
+}
+
+// switchConvert - Convert the switch statement into a binary lookup of
+// the case values. The function recursively builds this tree.
+//
+BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
+ Value* Val, BasicBlock* OrigBlock,
+ BasicBlock* Default)
+{
+ unsigned Size = End - Begin;
+
+ if (Size == 1)
+ return newLeafBlock(*Begin, Val, OrigBlock, Default);
+
+ unsigned Mid = Size / 2;
+ std::vector<CaseRange> LHS(Begin, Begin + Mid);
+ DOUT << "LHS: " << LHS << "\n";
+ std::vector<CaseRange> RHS(Begin + Mid, End);
+ DOUT << "RHS: " << RHS << "\n";
+
+ CaseRange& Pivot = *(Begin + Mid);
+ DEBUG( DOUT << "Pivot ==> "
+ << cast<ConstantInt>(Pivot.Low)->getValue().toStringSigned(10)
+ << " -"
+ << cast<ConstantInt>(Pivot.High)->getValue().toStringSigned(10)
+ << "\n");
+
+ BasicBlock* LBranch = switchConvert(LHS.begin(), LHS.end(), Val,
+ OrigBlock, Default);
+ BasicBlock* RBranch = switchConvert(RHS.begin(), RHS.end(), Val,
+ OrigBlock, Default);
+
+ // Create a new node that checks if the value is < pivot. Go to the
+ // left branch if it is and right branch if not.
+ Function* F = OrigBlock->getParent();
+ BasicBlock* NewNode = new BasicBlock("NodeBlock");
+ Function::iterator FI = OrigBlock;
+ F->getBasicBlockList().insert(++FI, NewNode);
+
+ ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT, Val, Pivot.Low, "Pivot");
+ NewNode->getInstList().push_back(Comp);
+ new BranchInst(LBranch, RBranch, Comp, NewNode);
+ return NewNode;
+}
+
+// newLeafBlock - Create a new leaf block for the binary lookup tree. It
+// checks if the switch's value == the case's value. If not, then it
+// jumps to the default branch. At this point in the tree, the value
+// can't be another valid case value, so the jump to the "default" branch
+// is warranted.
+//
+BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val,
+ BasicBlock* OrigBlock,
+ BasicBlock* Default)
+{
+ Function* F = OrigBlock->getParent();
+ BasicBlock* NewLeaf = new BasicBlock("LeafBlock");
+ Function::iterator FI = OrigBlock;
+ F->getBasicBlockList().insert(++FI, NewLeaf);
+
+ // Emit comparison
+ ICmpInst* Comp = NULL;
+ if (Leaf.Low == Leaf.High) {
+ // Make the seteq instruction...
+ Comp = new ICmpInst(ICmpInst::ICMP_EQ, Val, Leaf.Low,
+ "SwitchLeaf", NewLeaf);
+ } else {
+ // Make range comparison
+ if (cast<ConstantInt>(Leaf.Low)->isMinValue(true /*isSigned*/)) {
+ // Val >= Min && Val <= Hi --> Val <= Hi
+ Comp = new ICmpInst(ICmpInst::ICMP_SLE, Val, Leaf.High,
+ "SwitchLeaf", NewLeaf);
+ } else if (cast<ConstantInt>(Leaf.Low)->isZero()) {
+ // Val >= 0 && Val <= Hi --> Val <=u Hi
+ Comp = new ICmpInst(ICmpInst::ICMP_ULE, Val, Leaf.High,
+ "SwitchLeaf", NewLeaf);
+ } else {
+ // Emit V-Lo <=u Hi-Lo
+ Constant* NegLo = ConstantExpr::getNeg(Leaf.Low);
+ Instruction* Add = BinaryOperator::createAdd(Val, NegLo,
+ Val->getName()+".off",
+ NewLeaf);
+ Constant *UpperBound = ConstantExpr::getAdd(NegLo, Leaf.High);
+ Comp = new ICmpInst(ICmpInst::ICMP_ULE, Add, UpperBound,
+ "SwitchLeaf", NewLeaf);
+ }
+ }
+
+ // Make the conditional branch...
+ BasicBlock* Succ = Leaf.BB;
+ new BranchInst(Succ, Default, Comp, NewLeaf);
+
+ // If there were any PHI nodes in this successor, rewrite one entry
+ // from OrigBlock to come from NewLeaf.
+ for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
+ PHINode* PN = cast<PHINode>(I);
+ // Remove all but one incoming entries from the cluster
+ uint64_t Range = cast<ConstantInt>(Leaf.High)->getSExtValue() -
+ cast<ConstantInt>(Leaf.Low)->getSExtValue();
+ for (uint64_t j = 0; j < Range; ++j) {
+ PN->removeIncomingValue(OrigBlock);
+ }
+
+ int BlockIdx = PN->getBasicBlockIndex(OrigBlock);
+ assert(BlockIdx != -1 && "Switch didn't go to this successor??");
+ PN->setIncomingBlock((unsigned)BlockIdx, NewLeaf);
+ }
+
+ return NewLeaf;
+}
+
+// Clusterify - Transform simple list of Cases into list of CaseRange's
+unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
+ unsigned numCmps = 0;
+
+ // Start with "simple" cases
+ for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
+ Cases.push_back(CaseRange(SI->getSuccessorValue(i),
+ SI->getSuccessorValue(i),
+ SI->getSuccessor(i)));
+ sort(Cases.begin(), Cases.end(), CaseCmp());
+
+ // Merge case into clusters
+ if (Cases.size()>=2)
+ for (CaseItr I=Cases.begin(), J=++(Cases.begin()), E=Cases.end(); J!=E; ) {
+ int64_t nextValue = cast<ConstantInt>(J->Low)->getSExtValue();
+ int64_t currentValue = cast<ConstantInt>(I->High)->getSExtValue();
+ BasicBlock* nextBB = J->BB;
+ BasicBlock* currentBB = I->BB;
+
+ // If the two neighboring cases go to the same destination, merge them
+ // into a single case.
+ if ((nextValue-currentValue==1) && (currentBB == nextBB)) {
+ I->High = J->High;
+ J = Cases.erase(J);
+ } else {
+ I = J++;
+ }
+ }
+
+ for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) {
+ if (I->Low != I->High)
+ // A range counts double, since it requires two compares.
+ ++numCmps;
+ }
+
+ return numCmps;
+}
+
+// processSwitchInst - Replace the specified switch instruction with a sequence
+// of chained if-then insts in a balanced binary search.
+//
+void LowerSwitch::processSwitchInst(SwitchInst *SI) {
+ BasicBlock *CurBlock = SI->getParent();
+ BasicBlock *OrigBlock = CurBlock;
+ Function *F = CurBlock->getParent();
+ Value *Val = SI->getOperand(0); // The value we are switching on...
+ BasicBlock* Default = SI->getDefaultDest();
+
+ // If there is only the default destination, don't bother with the code below.
+ if (SI->getNumOperands() == 2) {
+ new BranchInst(SI->getDefaultDest(), CurBlock);
+ CurBlock->getInstList().erase(SI);
+ return;
+ }
+
+ // Create a new, empty default block so that the new hierarchy of
+ // if-then statements go to this and the PHI nodes are happy.
+ BasicBlock* NewDefault = new BasicBlock("NewDefault");
+ F->getBasicBlockList().insert(Default, NewDefault);
+
+ new BranchInst(Default, NewDefault);
+
+ // If there is an entry in any PHI nodes for the default edge, make sure
+ // to update them as well.
+ for (BasicBlock::iterator I = Default->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ int BlockIdx = PN->getBasicBlockIndex(OrigBlock);
+ assert(BlockIdx != -1 && "Switch didn't go to this successor??");
+ PN->setIncomingBlock((unsigned)BlockIdx, NewDefault);
+ }
+
+ // Prepare cases vector.
+ CaseVector Cases;
+ unsigned numCmps = Clusterify(Cases, SI);
+
+ DOUT << "Clusterify finished. Total clusters: " << Cases.size()
+ << ". Total compares: " << numCmps << "\n";
+ DOUT << "Cases: " << Cases << "\n";
+
+ BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val,
+ OrigBlock, NewDefault);
+
+ // Branch to our shiny new if-then stuff...
+ new BranchInst(SwitchBlock, OrigBlock);
+
+ // We are now done with the switch instruction, delete it.
+ CurBlock->getInstList().erase(SI);
+}
diff --git a/lib/Transforms/Utils/Makefile b/lib/Transforms/Utils/Makefile
new file mode 100644
index 0000000..26fc426
--- /dev/null
+++ b/lib/Transforms/Utils/Makefile
@@ -0,0 +1,15 @@
+##===- lib/Transforms/Utils/Makefile -----------------------*- Makefile -*-===##
+#
+# The LLVM Compiler Infrastructure
+#
+# This file was developed by the LLVM research group and is distributed under
+# the University of Illinois Open Source License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+LIBRARYNAME = LLVMTransformUtils
+BUILD_ARCHIVE = 1
+
+include $(LEVEL)/Makefile.common
+
diff --git a/lib/Transforms/Utils/Mem2Reg.cpp b/lib/Transforms/Utils/Mem2Reg.cpp
new file mode 100644
index 0000000..d67b3de
--- /dev/null
+++ b/lib/Transforms/Utils/Mem2Reg.cpp
@@ -0,0 +1,93 @@
+//===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is a simple pass wrapper around the PromoteMemToReg function call
+// exposed by the Utils library.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "mem2reg"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+STATISTIC(NumPromoted, "Number of alloca's promoted");
+
+namespace {
+ struct VISIBILITY_HIDDEN PromotePass : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ PromotePass() : FunctionPass((intptr_t)&ID) {}
+
+ // runOnFunction - To run this pass, first we calculate the alloca
+ // instructions that are safe for promotion, then we promote each one.
+ //
+ virtual bool runOnFunction(Function &F);
+
+ // getAnalysisUsage - We need dominance frontiers
+ //
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTree>();
+ AU.addRequired<DominanceFrontier>();
+ AU.setPreservesCFG();
+ // This is a cluster of orthogonal Transforms
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ AU.addPreservedID(LowerAllocationsID);
+ }
+ };
+
+ char PromotePass::ID = 0;
+ RegisterPass<PromotePass> X("mem2reg", "Promote Memory to Register");
+} // end of anonymous namespace
+
+bool PromotePass::runOnFunction(Function &F) {
+ std::vector<AllocaInst*> Allocas;
+
+ BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
+
+ bool Changed = false;
+
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
+
+ while (1) {
+ Allocas.clear();
+
+ // Find allocas that are safe to promote, by looking at all instructions in
+ // the entry node
+ for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
+ if (isAllocaPromotable(AI))
+ Allocas.push_back(AI);
+
+ if (Allocas.empty()) break;
+
+ PromoteMemToReg(Allocas, DT, DF);
+ NumPromoted += Allocas.size();
+ Changed = true;
+ }
+
+ return Changed;
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::PromoteMemoryToRegisterID = X.getPassInfo();
+// createPromoteMemoryToRegister - Provide an entry point to create this pass.
+//
+FunctionPass *llvm::createPromoteMemoryToRegisterPass() {
+ return new PromotePass();
+}
diff --git a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
new file mode 100644
index 0000000..259a5a2
--- /dev/null
+++ b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -0,0 +1,835 @@
+//===- PromoteMemoryToRegister.cpp - Convert allocas to registers ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file promote memory references to be register references. It promotes
+// alloca instructions which only have loads and stores as uses. An alloca is
+// transformed by using dominator frontiers to place PHI nodes, then traversing
+// the function in depth-first order to rewrite loads and stores as appropriate.
+// This is just the standard SSA construction algorithm to construct "pruned"
+// SSA form.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/AliasSetTracker.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include <algorithm>
+using namespace llvm;
+
+// Provide DenseMapKeyInfo for all pointers.
+namespace llvm {
+template<>
+struct DenseMapKeyInfo<std::pair<BasicBlock*, unsigned> > {
+ static inline std::pair<BasicBlock*, unsigned> getEmptyKey() {
+ return std::make_pair((BasicBlock*)-1, ~0U);
+ }
+ static inline std::pair<BasicBlock*, unsigned> getTombstoneKey() {
+ return std::make_pair((BasicBlock*)-2, 0U);
+ }
+ static unsigned getHashValue(const std::pair<BasicBlock*, unsigned> &Val) {
+ return DenseMapKeyInfo<void*>::getHashValue(Val.first) + Val.second*2;
+ }
+ static bool isPod() { return true; }
+};
+}
+
+/// isAllocaPromotable - Return true if this alloca is legal for promotion.
+/// This is true if there are only loads and stores to the alloca.
+///
+bool llvm::isAllocaPromotable(const AllocaInst *AI) {
+ // FIXME: If the memory unit is of pointer or integer type, we can permit
+ // assignments to subsections of the memory unit.
+
+ // Only allow direct loads and stores...
+ for (Value::use_const_iterator UI = AI->use_begin(), UE = AI->use_end();
+ UI != UE; ++UI) // Loop over all of the uses of the alloca
+ if (isa<LoadInst>(*UI)) {
+ // noop
+ } else if (const StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ if (SI->getOperand(0) == AI)
+ return false; // Don't allow a store OF the AI, only INTO the AI.
+ } else {
+ return false; // Not a load or store.
+ }
+
+ return true;
+}
+
+namespace {
+
+ // Data package used by RenamePass()
+ class VISIBILITY_HIDDEN RenamePassData {
+ public:
+ RenamePassData(BasicBlock *B, BasicBlock *P,
+ const std::vector<Value *> &V) : BB(B), Pred(P), Values(V) {}
+ BasicBlock *BB;
+ BasicBlock *Pred;
+ std::vector<Value *> Values;
+ };
+
+ struct VISIBILITY_HIDDEN PromoteMem2Reg {
+ /// Allocas - The alloca instructions being promoted.
+ ///
+ std::vector<AllocaInst*> Allocas;
+ SmallVector<AllocaInst*, 16> &RetryList;
+ DominatorTree &DT;
+ DominanceFrontier &DF;
+
+ /// AST - An AliasSetTracker object to update. If null, don't update it.
+ ///
+ AliasSetTracker *AST;
+
+ /// AllocaLookup - Reverse mapping of Allocas.
+ ///
+ std::map<AllocaInst*, unsigned> AllocaLookup;
+
+ /// NewPhiNodes - The PhiNodes we're adding.
+ ///
+ DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*> NewPhiNodes;
+
+ /// PhiToAllocaMap - For each PHI node, keep track of which entry in Allocas
+ /// it corresponds to.
+ DenseMap<PHINode*, unsigned> PhiToAllocaMap;
+
+ /// PointerAllocaValues - If we are updating an AliasSetTracker, then for
+ /// each alloca that is of pointer type, we keep track of what to copyValue
+ /// to the inserted PHI nodes here.
+ ///
+ std::vector<Value*> PointerAllocaValues;
+
+ /// Visited - The set of basic blocks the renamer has already visited.
+ ///
+ SmallPtrSet<BasicBlock*, 16> Visited;
+
+ /// BBNumbers - Contains a stable numbering of basic blocks to avoid
+ /// non-determinstic behavior.
+ DenseMap<BasicBlock*, unsigned> BBNumbers;
+
+ /// RenamePassWorkList - Worklist used by RenamePass()
+ std::vector<RenamePassData> RenamePassWorkList;
+
+ public:
+ PromoteMem2Reg(const std::vector<AllocaInst*> &A,
+ SmallVector<AllocaInst*, 16> &Retry, DominatorTree &dt,
+ DominanceFrontier &df, AliasSetTracker *ast)
+ : Allocas(A), RetryList(Retry), DT(dt), DF(df), AST(ast) {}
+
+ void run();
+
+ /// properlyDominates - Return true if I1 properly dominates I2.
+ ///
+ bool properlyDominates(Instruction *I1, Instruction *I2) const {
+ if (InvokeInst *II = dyn_cast<InvokeInst>(I1))
+ I1 = II->getNormalDest()->begin();
+ return DT.properlyDominates(I1->getParent(), I2->getParent());
+ }
+
+ /// dominates - Return true if BB1 dominates BB2 using the DominatorTree.
+ ///
+ bool dominates(BasicBlock *BB1, BasicBlock *BB2) const {
+ return DT.dominates(BB1, BB2);
+ }
+
+ private:
+ void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
+ SmallPtrSet<PHINode*, 16> &DeadPHINodes);
+ bool PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
+ void PromoteLocallyUsedAllocas(BasicBlock *BB,
+ const std::vector<AllocaInst*> &AIs);
+
+ void RenamePass(BasicBlock *BB, BasicBlock *Pred,
+ std::vector<Value*> &IncVals);
+ bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version,
+ SmallPtrSet<PHINode*, 16> &InsertedPHINodes);
+ };
+
+} // end of anonymous namespace
+
+void PromoteMem2Reg::run() {
+ Function &F = *DF.getRoot()->getParent();
+
+ // LocallyUsedAllocas - Keep track of all of the alloca instructions which are
+ // only used in a single basic block. These instructions can be efficiently
+ // promoted by performing a single linear scan over that one block. Since
+ // individual basic blocks are sometimes large, we group together all allocas
+ // that are live in a single basic block by the basic block they are live in.
+ std::map<BasicBlock*, std::vector<AllocaInst*> > LocallyUsedAllocas;
+
+ if (AST) PointerAllocaValues.resize(Allocas.size());
+
+ for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
+ AllocaInst *AI = Allocas[AllocaNum];
+
+ assert(isAllocaPromotable(AI) &&
+ "Cannot promote non-promotable alloca!");
+ assert(AI->getParent()->getParent() == &F &&
+ "All allocas should be in the same function, which is same as DF!");
+
+ if (AI->use_empty()) {
+ // If there are no uses of the alloca, just delete it now.
+ if (AST) AST->deleteValue(AI);
+ AI->eraseFromParent();
+
+ // Remove the alloca from the Allocas list, since it has been processed
+ Allocas[AllocaNum] = Allocas.back();
+ Allocas.pop_back();
+ --AllocaNum;
+ continue;
+ }
+
+ // Calculate the set of read and write-locations for each alloca. This is
+ // analogous to finding the 'uses' and 'definitions' of each variable.
+ std::vector<BasicBlock*> DefiningBlocks;
+ std::vector<BasicBlock*> UsingBlocks;
+
+ StoreInst *OnlyStore = 0;
+ BasicBlock *OnlyBlock = 0;
+ bool OnlyUsedInOneBlock = true;
+
+ // As we scan the uses of the alloca instruction, keep track of stores, and
+ // decide whether all of the loads and stores to the alloca are within the
+ // same basic block.
+ Value *AllocaPointerVal = 0;
+ for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E;++U){
+ Instruction *User = cast<Instruction>(*U);
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ // Remember the basic blocks which define new values for the alloca
+ DefiningBlocks.push_back(SI->getParent());
+ AllocaPointerVal = SI->getOperand(0);
+ OnlyStore = SI;
+ } else {
+ LoadInst *LI = cast<LoadInst>(User);
+ // Otherwise it must be a load instruction, keep track of variable reads
+ UsingBlocks.push_back(LI->getParent());
+ AllocaPointerVal = LI;
+ }
+
+ if (OnlyUsedInOneBlock) {
+ if (OnlyBlock == 0)
+ OnlyBlock = User->getParent();
+ else if (OnlyBlock != User->getParent())
+ OnlyUsedInOneBlock = false;
+ }
+ }
+
+ // If the alloca is only read and written in one basic block, just perform a
+ // linear sweep over the block to eliminate it.
+ if (OnlyUsedInOneBlock) {
+ LocallyUsedAllocas[OnlyBlock].push_back(AI);
+
+ // Remove the alloca from the Allocas list, since it will be processed.
+ Allocas[AllocaNum] = Allocas.back();
+ Allocas.pop_back();
+ --AllocaNum;
+ continue;
+ }
+
+ // If there is only a single store to this value, replace any loads of
+ // it that are directly dominated by the definition with the value stored.
+ if (DefiningBlocks.size() == 1) {
+ // Be aware of loads before the store.
+ std::set<BasicBlock*> ProcessedBlocks;
+ for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
+ // If the store dominates the block and if we haven't processed it yet,
+ // do so now.
+ if (dominates(OnlyStore->getParent(), UsingBlocks[i]))
+ if (ProcessedBlocks.insert(UsingBlocks[i]).second) {
+ BasicBlock *UseBlock = UsingBlocks[i];
+
+ // If the use and store are in the same block, do a quick scan to
+ // verify that there are no uses before the store.
+ if (UseBlock == OnlyStore->getParent()) {
+ BasicBlock::iterator I = UseBlock->begin();
+ for (; &*I != OnlyStore; ++I) { // scan block for store.
+ if (isa<LoadInst>(I) && I->getOperand(0) == AI)
+ break;
+ }
+ if (&*I != OnlyStore) break; // Do not handle this case.
+ }
+
+ // Otherwise, if this is a different block or if all uses happen
+ // after the store, do a simple linear scan to replace loads with
+ // the stored value.
+ for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
+ I != E; ) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
+ if (LI->getOperand(0) == AI) {
+ LI->replaceAllUsesWith(OnlyStore->getOperand(0));
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ LI->eraseFromParent();
+ }
+ }
+ }
+
+ // Finally, remove this block from the UsingBlock set.
+ UsingBlocks[i] = UsingBlocks.back();
+ --i; --e;
+ }
+
+ // Finally, after the scan, check to see if the store is all that is left.
+ if (UsingBlocks.empty()) {
+ // The alloca has been processed, move on.
+ Allocas[AllocaNum] = Allocas.back();
+ Allocas.pop_back();
+ --AllocaNum;
+ continue;
+ }
+ }
+
+
+ if (AST)
+ PointerAllocaValues[AllocaNum] = AllocaPointerVal;
+
+ // If we haven't computed a numbering for the BB's in the function, do so
+ // now.
+ if (BBNumbers.empty()) {
+ unsigned ID = 0;
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ BBNumbers[I] = ID++;
+ }
+
+ // Compute the locations where PhiNodes need to be inserted. Look at the
+ // dominance frontier of EACH basic-block we have a write in.
+ //
+ unsigned CurrentVersion = 0;
+ SmallPtrSet<PHINode*, 16> InsertedPHINodes;
+ std::vector<std::pair<unsigned, BasicBlock*> > DFBlocks;
+ while (!DefiningBlocks.empty()) {
+ BasicBlock *BB = DefiningBlocks.back();
+ DefiningBlocks.pop_back();
+
+ // Look up the DF for this write, add it to PhiNodes
+ DominanceFrontier::const_iterator it = DF.find(BB);
+ if (it != DF.end()) {
+ const DominanceFrontier::DomSetType &S = it->second;
+
+ // In theory we don't need the indirection through the DFBlocks vector.
+ // In practice, the order of calling QueuePhiNode would depend on the
+ // (unspecified) ordering of basic blocks in the dominance frontier,
+ // which would give PHI nodes non-determinstic subscripts. Fix this by
+ // processing blocks in order of the occurance in the function.
+ for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
+ PE = S.end(); P != PE; ++P)
+ DFBlocks.push_back(std::make_pair(BBNumbers[*P], *P));
+
+ // Sort by which the block ordering in the function.
+ std::sort(DFBlocks.begin(), DFBlocks.end());
+
+ for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i) {
+ BasicBlock *BB = DFBlocks[i].second;
+ if (QueuePhiNode(BB, AllocaNum, CurrentVersion, InsertedPHINodes))
+ DefiningBlocks.push_back(BB);
+ }
+ DFBlocks.clear();
+ }
+ }
+
+ // Now that we have inserted PHI nodes along the Iterated Dominance Frontier
+ // of the writes to the variable, scan through the reads of the variable,
+ // marking PHI nodes which are actually necessary as alive (by removing them
+ // from the InsertedPHINodes set). This is not perfect: there may PHI
+ // marked alive because of loads which are dominated by stores, but there
+ // will be no unmarked PHI nodes which are actually used.
+ //
+ for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
+ MarkDominatingPHILive(UsingBlocks[i], AllocaNum, InsertedPHINodes);
+ UsingBlocks.clear();
+
+ // If there are any PHI nodes which are now known to be dead, remove them!
+ for (SmallPtrSet<PHINode*, 16>::iterator I = InsertedPHINodes.begin(),
+ E = InsertedPHINodes.end(); I != E; ++I) {
+ PHINode *PN = *I;
+ bool Erased=NewPhiNodes.erase(std::make_pair(PN->getParent(), AllocaNum));
+ Erased=Erased;
+ assert(Erased && "PHI already removed?");
+
+ if (AST && isa<PointerType>(PN->getType()))
+ AST->deleteValue(PN);
+ PN->eraseFromParent();
+ PhiToAllocaMap.erase(PN);
+ }
+
+ // Keep the reverse mapping of the 'Allocas' array.
+ AllocaLookup[Allocas[AllocaNum]] = AllocaNum;
+ }
+
+ // Process all allocas which are only used in a single basic block.
+ for (std::map<BasicBlock*, std::vector<AllocaInst*> >::iterator I =
+ LocallyUsedAllocas.begin(), E = LocallyUsedAllocas.end(); I != E; ++I){
+ const std::vector<AllocaInst*> &LocAllocas = I->second;
+ assert(!LocAllocas.empty() && "empty alloca list??");
+
+ // It's common for there to only be one alloca in the list. Handle it
+ // efficiently.
+ if (LocAllocas.size() == 1) {
+ // If we can do the quick promotion pass, do so now.
+ if (PromoteLocallyUsedAlloca(I->first, LocAllocas[0]))
+ RetryList.push_back(LocAllocas[0]); // Failed, retry later.
+ } else {
+ // Locally promote anything possible. Note that if this is unable to
+ // promote a particular alloca, it puts the alloca onto the Allocas vector
+ // for global processing.
+ PromoteLocallyUsedAllocas(I->first, LocAllocas);
+ }
+ }
+
+ if (Allocas.empty())
+ return; // All of the allocas must have been trivial!
+
+ // Set the incoming values for the basic block to be null values for all of
+ // the alloca's. We do this in case there is a load of a value that has not
+ // been stored yet. In this case, it will get this null value.
+ //
+ std::vector<Value *> Values(Allocas.size());
+ for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
+ Values[i] = UndefValue::get(Allocas[i]->getAllocatedType());
+
+ // Walks all basic blocks in the function performing the SSA rename algorithm
+ // and inserting the phi nodes we marked as necessary
+ //
+ RenamePassWorkList.clear();
+ RenamePassWorkList.push_back(RenamePassData(F.begin(), 0, Values));
+ while(!RenamePassWorkList.empty()) {
+ RenamePassData RPD = RenamePassWorkList.back();
+ RenamePassWorkList.pop_back();
+ // RenamePass may add new worklist entries.
+ RenamePass(RPD.BB, RPD.Pred, RPD.Values);
+ }
+
+ // The renamer uses the Visited set to avoid infinite loops. Clear it now.
+ Visited.clear();
+
+ // Remove the allocas themselves from the function.
+ for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
+ Instruction *A = Allocas[i];
+
+ // If there are any uses of the alloca instructions left, they must be in
+ // sections of dead code that were not processed on the dominance frontier.
+ // Just delete the users now.
+ //
+ if (!A->use_empty())
+ A->replaceAllUsesWith(UndefValue::get(A->getType()));
+ if (AST) AST->deleteValue(A);
+ A->eraseFromParent();
+ }
+
+
+ // Loop over all of the PHI nodes and see if there are any that we can get
+ // rid of because they merge all of the same incoming values. This can
+ // happen due to undef values coming into the PHI nodes. This process is
+ // iterative, because eliminating one PHI node can cause others to be removed.
+ bool EliminatedAPHI = true;
+ while (EliminatedAPHI) {
+ EliminatedAPHI = false;
+
+ for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
+ NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E;) {
+ PHINode *PN = I->second;
+
+ // If this PHI node merges one value and/or undefs, get the value.
+ if (Value *V = PN->hasConstantValue(true)) {
+ if (!isa<Instruction>(V) ||
+ properlyDominates(cast<Instruction>(V), PN)) {
+ if (AST && isa<PointerType>(PN->getType()))
+ AST->deleteValue(PN);
+ PN->replaceAllUsesWith(V);
+ PN->eraseFromParent();
+ NewPhiNodes.erase(I++);
+ EliminatedAPHI = true;
+ continue;
+ }
+ }
+ ++I;
+ }
+ }
+
+ // At this point, the renamer has added entries to PHI nodes for all reachable
+ // code. Unfortunately, there may be unreachable blocks which the renamer
+ // hasn't traversed. If this is the case, the PHI nodes may not
+ // have incoming values for all predecessors. Loop over all PHI nodes we have
+ // created, inserting undef values if they are missing any incoming values.
+ //
+ for (DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator I =
+ NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E; ++I) {
+ // We want to do this once per basic block. As such, only process a block
+ // when we find the PHI that is the first entry in the block.
+ PHINode *SomePHI = I->second;
+ BasicBlock *BB = SomePHI->getParent();
+ if (&BB->front() != SomePHI)
+ continue;
+
+ // Count the number of preds for BB.
+ SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
+
+ // Only do work here if there the PHI nodes are missing incoming values. We
+ // know that all PHI nodes that were inserted in a block will have the same
+ // number of incoming values, so we can just check any of them.
+ if (SomePHI->getNumIncomingValues() == Preds.size())
+ continue;
+
+ // Ok, now we know that all of the PHI nodes are missing entries for some
+ // basic blocks. Start by sorting the incoming predecessors for efficient
+ // access.
+ std::sort(Preds.begin(), Preds.end());
+
+ // Now we loop through all BB's which have entries in SomePHI and remove
+ // them from the Preds list.
+ for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i) {
+ // Do a log(n) search of the Preds list for the entry we want.
+ SmallVector<BasicBlock*, 16>::iterator EntIt =
+ std::lower_bound(Preds.begin(), Preds.end(),
+ SomePHI->getIncomingBlock(i));
+ assert(EntIt != Preds.end() && *EntIt == SomePHI->getIncomingBlock(i)&&
+ "PHI node has entry for a block which is not a predecessor!");
+
+ // Remove the entry
+ Preds.erase(EntIt);
+ }
+
+ // At this point, the blocks left in the preds list must have dummy
+ // entries inserted into every PHI nodes for the block. Update all the phi
+ // nodes in this block that we are inserting (there could be phis before
+ // mem2reg runs).
+ unsigned NumBadPreds = SomePHI->getNumIncomingValues();
+ BasicBlock::iterator BBI = BB->begin();
+ while ((SomePHI = dyn_cast<PHINode>(BBI++)) &&
+ SomePHI->getNumIncomingValues() == NumBadPreds) {
+ Value *UndefVal = UndefValue::get(SomePHI->getType());
+ for (unsigned pred = 0, e = Preds.size(); pred != e; ++pred)
+ SomePHI->addIncoming(UndefVal, Preds[pred]);
+ }
+ }
+
+ NewPhiNodes.clear();
+}
+
+// MarkDominatingPHILive - Mem2Reg wants to construct "pruned" SSA form, not
+// "minimal" SSA form. To do this, it inserts all of the PHI nodes on the IDF
+// as usual (inserting the PHI nodes in the DeadPHINodes set), then processes
+// each read of the variable. For each block that reads the variable, this
+// function is called, which removes used PHI nodes from the DeadPHINodes set.
+// After all of the reads have been processed, any PHI nodes left in the
+// DeadPHINodes set are removed.
+//
+void PromoteMem2Reg::MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
+ SmallPtrSet<PHINode*, 16> &DeadPHINodes) {
+ // Scan the immediate dominators of this block looking for a block which has a
+ // PHI node for Alloca num. If we find it, mark the PHI node as being alive!
+ DomTreeNode *IDomNode = DT.getNode(BB);
+ for (DomTreeNode *IDom = IDomNode; IDom; IDom = IDom->getIDom()) {
+ BasicBlock *DomBB = IDom->getBlock();
+ DenseMap<std::pair<BasicBlock*, unsigned>, PHINode*>::iterator
+ I = NewPhiNodes.find(std::make_pair(DomBB, AllocaNum));
+ if (I != NewPhiNodes.end()) {
+ // Ok, we found an inserted PHI node which dominates this value.
+ PHINode *DominatingPHI = I->second;
+
+ // Find out if we previously thought it was dead. If so, mark it as being
+ // live by removing it from the DeadPHINodes set.
+ if (DeadPHINodes.erase(DominatingPHI)) {
+ // Now that we have marked the PHI node alive, also mark any PHI nodes
+ // which it might use as being alive as well.
+ for (pred_iterator PI = pred_begin(DomBB), PE = pred_end(DomBB);
+ PI != PE; ++PI)
+ MarkDominatingPHILive(*PI, AllocaNum, DeadPHINodes);
+ }
+ }
+ }
+}
+
+/// PromoteLocallyUsedAlloca - Many allocas are only used within a single basic
+/// block. If this is the case, avoid traversing the CFG and inserting a lot of
+/// potentially useless PHI nodes by just performing a single linear pass over
+/// the basic block using the Alloca.
+///
+/// If we cannot promote this alloca (because it is read before it is written),
+/// return true. This is necessary in cases where, due to control flow, the
+/// alloca is potentially undefined on some control flow paths. e.g. code like
+/// this is potentially correct:
+///
+/// for (...) { if (c) { A = undef; undef = B; } }
+///
+/// ... so long as A is not used before undef is set.
+///
+bool PromoteMem2Reg::PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI) {
+ assert(!AI->use_empty() && "There are no uses of the alloca!");
+
+ // Handle degenerate cases quickly.
+ if (AI->hasOneUse()) {
+ Instruction *U = cast<Instruction>(AI->use_back());
+ if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ // Must be a load of uninitialized value.
+ LI->replaceAllUsesWith(UndefValue::get(AI->getAllocatedType()));
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ } else {
+ // Otherwise it must be a store which is never read.
+ assert(isa<StoreInst>(U));
+ }
+ BB->getInstList().erase(U);
+ } else {
+ // Uses of the uninitialized memory location shall get undef.
+ Value *CurVal = 0;
+
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
+ Instruction *Inst = I++;
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ if (LI->getOperand(0) == AI) {
+ if (!CurVal) return true; // Could not locally promote!
+
+ // Loads just returns the "current value"...
+ LI->replaceAllUsesWith(CurVal);
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ BB->getInstList().erase(LI);
+ }
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ if (SI->getOperand(1) == AI) {
+ // Store updates the "current value"...
+ CurVal = SI->getOperand(0);
+ BB->getInstList().erase(SI);
+ }
+ }
+ }
+ }
+
+ // After traversing the basic block, there should be no more uses of the
+ // alloca, remove it now.
+ assert(AI->use_empty() && "Uses of alloca from more than one BB??");
+ if (AST) AST->deleteValue(AI);
+ AI->getParent()->getInstList().erase(AI);
+ return false;
+}
+
+/// PromoteLocallyUsedAllocas - This method is just like
+/// PromoteLocallyUsedAlloca, except that it processes multiple alloca
+/// instructions in parallel. This is important in cases where we have large
+/// basic blocks, as we don't want to rescan the entire basic block for each
+/// alloca which is locally used in it (which might be a lot).
+void PromoteMem2Reg::
+PromoteLocallyUsedAllocas(BasicBlock *BB, const std::vector<AllocaInst*> &AIs) {
+ std::map<AllocaInst*, Value*> CurValues;
+ for (unsigned i = 0, e = AIs.size(); i != e; ++i)
+ CurValues[AIs[i]] = 0; // Insert with null value
+
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
+ Instruction *Inst = I++;
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ // Is this a load of an alloca we are tracking?
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(LI->getOperand(0))) {
+ std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
+ if (AIt != CurValues.end()) {
+ // If loading an uninitialized value, allow the inter-block case to
+ // handle it. Due to control flow, this might actually be ok.
+ if (AIt->second == 0) { // Use of locally uninitialized value??
+ RetryList.push_back(AI); // Retry elsewhere.
+ CurValues.erase(AIt); // Stop tracking this here.
+ if (CurValues.empty()) return;
+ } else {
+ // Loads just returns the "current value"...
+ LI->replaceAllUsesWith(AIt->second);
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ BB->getInstList().erase(LI);
+ }
+ }
+ }
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(SI->getOperand(1))) {
+ std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
+ if (AIt != CurValues.end()) {
+ // Store updates the "current value"...
+ AIt->second = SI->getOperand(0);
+ BB->getInstList().erase(SI);
+ }
+ }
+ }
+ }
+}
+
+
+
+// QueuePhiNode - queues a phi-node to be added to a basic-block for a specific
+// Alloca returns true if there wasn't already a phi-node for that variable
+//
+bool PromoteMem2Reg::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo,
+ unsigned &Version,
+ SmallPtrSet<PHINode*, 16> &InsertedPHINodes) {
+ // Look up the basic-block in question.
+ PHINode *&PN = NewPhiNodes[std::make_pair(BB, AllocaNo)];
+
+ // If the BB already has a phi node added for the i'th alloca then we're done!
+ if (PN) return false;
+
+ // Create a PhiNode using the dereferenced type... and add the phi-node to the
+ // BasicBlock.
+ PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
+ Allocas[AllocaNo]->getName() + "." +
+ utostr(Version++), BB->begin());
+ PhiToAllocaMap[PN] = AllocaNo;
+
+ InsertedPHINodes.insert(PN);
+
+ if (AST && isa<PointerType>(PN->getType()))
+ AST->copyValue(PointerAllocaValues[AllocaNo], PN);
+
+ return true;
+}
+
+
+// RenamePass - Recursively traverse the CFG of the function, renaming loads and
+// stores to the allocas which we are promoting. IncomingVals indicates what
+// value each Alloca contains on exit from the predecessor block Pred.
+//
+void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
+ std::vector<Value*> &IncomingVals) {
+ // If we are inserting any phi nodes into this BB, they will already be in the
+ // block.
+ if (PHINode *APN = dyn_cast<PHINode>(BB->begin())) {
+ // Pred may have multiple edges to BB. If so, we want to add N incoming
+ // values to each PHI we are inserting on the first time we see the edge.
+ // Check to see if APN already has incoming values from Pred. This also
+ // prevents us from modifying PHI nodes that are not currently being
+ // inserted.
+ bool HasPredEntries = false;
+ for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
+ if (APN->getIncomingBlock(i) == Pred) {
+ HasPredEntries = true;
+ break;
+ }
+ }
+
+ // If we have PHI nodes to update, compute the number of edges from Pred to
+ // BB.
+ if (!HasPredEntries) {
+ TerminatorInst *PredTerm = Pred->getTerminator();
+ unsigned NumEdges = 0;
+ for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) {
+ if (PredTerm->getSuccessor(i) == BB)
+ ++NumEdges;
+ }
+ assert(NumEdges && "Must be at least one edge from Pred to BB!");
+
+ // Add entries for all the phis.
+ BasicBlock::iterator PNI = BB->begin();
+ do {
+ unsigned AllocaNo = PhiToAllocaMap[APN];
+
+ // Add N incoming values to the PHI node.
+ for (unsigned i = 0; i != NumEdges; ++i)
+ APN->addIncoming(IncomingVals[AllocaNo], Pred);
+
+ // The currently active variable for this block is now the PHI.
+ IncomingVals[AllocaNo] = APN;
+
+ // Get the next phi node.
+ ++PNI;
+ APN = dyn_cast<PHINode>(PNI);
+ if (APN == 0) break;
+
+ // Verify it doesn't already have entries for Pred. If it does, it is
+ // not being inserted by this mem2reg invocation.
+ HasPredEntries = false;
+ for (unsigned i = 0, e = APN->getNumIncomingValues(); i != e; ++i) {
+ if (APN->getIncomingBlock(i) == Pred) {
+ HasPredEntries = true;
+ break;
+ }
+ }
+ } while (!HasPredEntries);
+ }
+ }
+
+ // Don't revisit blocks.
+ if (!Visited.insert(BB)) return;
+
+ for (BasicBlock::iterator II = BB->begin(); !isa<TerminatorInst>(II); ) {
+ Instruction *I = II++; // get the instruction, increment iterator
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ if (AllocaInst *Src = dyn_cast<AllocaInst>(LI->getPointerOperand())) {
+ std::map<AllocaInst*, unsigned>::iterator AI = AllocaLookup.find(Src);
+ if (AI != AllocaLookup.end()) {
+ Value *V = IncomingVals[AI->second];
+
+ // walk the use list of this load and replace all uses with r
+ LI->replaceAllUsesWith(V);
+ if (AST && isa<PointerType>(LI->getType()))
+ AST->deleteValue(LI);
+ BB->getInstList().erase(LI);
+ }
+ }
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ // Delete this instruction and mark the name as the current holder of the
+ // value
+ if (AllocaInst *Dest = dyn_cast<AllocaInst>(SI->getPointerOperand())) {
+ std::map<AllocaInst *, unsigned>::iterator ai = AllocaLookup.find(Dest);
+ if (ai != AllocaLookup.end()) {
+ // what value were we writing?
+ IncomingVals[ai->second] = SI->getOperand(0);
+ BB->getInstList().erase(SI);
+ }
+ }
+ }
+ }
+
+ // Recurse to our successors.
+ TerminatorInst *TI = BB->getTerminator();
+ for (unsigned i = 0; i != TI->getNumSuccessors(); i++)
+ RenamePassWorkList.push_back(RenamePassData(TI->getSuccessor(i), BB, IncomingVals));
+}
+
+/// PromoteMemToReg - Promote the specified list of alloca instructions into
+/// scalar registers, inserting PHI nodes as appropriate. This function makes
+/// use of DominanceFrontier information. This function does not modify the CFG
+/// of the function at all. All allocas must be from the same function.
+///
+/// If AST is specified, the specified tracker is updated to reflect changes
+/// made to the IR.
+///
+void llvm::PromoteMemToReg(const std::vector<AllocaInst*> &Allocas,
+ DominatorTree &DT, DominanceFrontier &DF,
+ AliasSetTracker *AST) {
+ // If there is nothing to do, bail out...
+ if (Allocas.empty()) return;
+
+ SmallVector<AllocaInst*, 16> RetryList;
+ PromoteMem2Reg(Allocas, RetryList, DT, DF, AST).run();
+
+ // PromoteMem2Reg may not have been able to promote all of the allocas in one
+ // pass, run it again if needed.
+ std::vector<AllocaInst*> NewAllocas;
+ while (!RetryList.empty()) {
+ // If we need to retry some allocas, this is due to there being no store
+ // before a read in a local block. To counteract this, insert a store of
+ // undef into the alloca right after the alloca itself.
+ for (unsigned i = 0, e = RetryList.size(); i != e; ++i) {
+ BasicBlock::iterator BBI = RetryList[i];
+
+ new StoreInst(UndefValue::get(RetryList[i]->getAllocatedType()),
+ RetryList[i], ++BBI);
+ }
+
+ NewAllocas.assign(RetryList.begin(), RetryList.end());
+ RetryList.clear();
+ PromoteMem2Reg(NewAllocas, RetryList, DT, DF, AST).run();
+ NewAllocas.clear();
+ }
+}
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
new file mode 100644
index 0000000..6c34d02
--- /dev/null
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -0,0 +1,1905 @@
+//===- SimplifyCFG.cpp - Code to perform CFG simplification ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Peephole optimize the CFG.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "simplifycfg"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include <algorithm>
+#include <functional>
+#include <set>
+#include <map>
+using namespace llvm;
+
+/// SafeToMergeTerminators - Return true if it is safe to merge these two
+/// terminator instructions together.
+///
+static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) {
+ if (SI1 == SI2) return false; // Can't merge with self!
+
+ // It is not safe to merge these two switch instructions if they have a common
+ // successor, and if that successor has a PHI node, and if *that* PHI node has
+ // conflicting incoming values from the two switch blocks.
+ BasicBlock *SI1BB = SI1->getParent();
+ BasicBlock *SI2BB = SI2->getParent();
+ SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB));
+
+ for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I)
+ if (SI1Succs.count(*I))
+ for (BasicBlock::iterator BBI = (*I)->begin();
+ isa<PHINode>(BBI); ++BBI) {
+ PHINode *PN = cast<PHINode>(BBI);
+ if (PN->getIncomingValueForBlock(SI1BB) !=
+ PN->getIncomingValueForBlock(SI2BB))
+ return false;
+ }
+
+ return true;
+}
+
+/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will
+/// now be entries in it from the 'NewPred' block. The values that will be
+/// flowing into the PHI nodes will be the same as those coming in from
+/// ExistPred, an existing predecessor of Succ.
+static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred,
+ BasicBlock *ExistPred) {
+ assert(std::find(succ_begin(ExistPred), succ_end(ExistPred), Succ) !=
+ succ_end(ExistPred) && "ExistPred is not a predecessor of Succ!");
+ if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do
+
+ for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ Value *V = PN->getIncomingValueForBlock(ExistPred);
+ PN->addIncoming(V, NewPred);
+ }
+}
+
+// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
+// almost-empty BB ending in an unconditional branch to Succ, into succ.
+//
+// Assumption: Succ is the single successor for BB.
+//
+static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
+ assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
+
+ // Check to see if one of the predecessors of BB is already a predecessor of
+ // Succ. If so, we cannot do the transformation if there are any PHI nodes
+ // with incompatible values coming in from the two edges!
+ //
+ if (isa<PHINode>(Succ->front())) {
+ SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
+ for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
+ PI != PE; ++PI)
+ if (BBPreds.count(*PI)) {
+ // Loop over all of the PHI nodes checking to see if there are
+ // incompatible values coming in.
+ for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ // Loop up the entries in the PHI node for BB and for *PI if the
+ // values coming in are non-equal, we cannot merge these two blocks
+ // (instead we should insert a conditional move or something, then
+ // merge the blocks).
+ if (PN->getIncomingValueForBlock(BB) !=
+ PN->getIncomingValueForBlock(*PI))
+ return false; // Values are not equal...
+ }
+ }
+ }
+
+ // Finally, if BB has PHI nodes that are used by things other than the PHIs in
+ // Succ and Succ has predecessors that are not Succ and not Pred, we cannot
+ // fold these blocks, as we don't know whether BB dominates Succ or not to
+ // update the PHI nodes correctly.
+ if (!isa<PHINode>(BB->begin()) || Succ->getSinglePredecessor()) return true;
+
+ // If the predecessors of Succ are only BB and Succ itself, handle it.
+ bool IsSafe = true;
+ for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
+ if (*PI != Succ && *PI != BB) {
+ IsSafe = false;
+ break;
+ }
+ if (IsSafe) return true;
+
+ // If the PHI nodes in BB are only used by instructions in Succ, we are ok if
+ // BB and Succ have no common predecessors.
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end(); UI != E;
+ ++UI)
+ if (cast<Instruction>(*UI)->getParent() != Succ)
+ return false;
+ }
+
+ // Scan the predecessor sets of BB and Succ, making sure there are no common
+ // predecessors. Common predecessors would cause us to build a phi node with
+ // differing incoming values, which is not legal.
+ SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
+ for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
+ if (BBPreds.count(*PI))
+ return false;
+
+ return true;
+}
+
+/// TryToSimplifyUncondBranchFromEmptyBlock - BB contains an unconditional
+/// branch to Succ, and contains no instructions other than PHI nodes and the
+/// branch. If possible, eliminate BB.
+static bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
+ BasicBlock *Succ) {
+ // If our successor has PHI nodes, then we need to update them to include
+ // entries for BB's predecessors, not for BB itself. Be careful though,
+ // if this transformation fails (returns true) then we cannot do this
+ // transformation!
+ //
+ if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
+
+ DOUT << "Killing Trivial BB: \n" << *BB;
+
+ if (isa<PHINode>(Succ->begin())) {
+ // If there is more than one pred of succ, and there are PHI nodes in
+ // the successor, then we need to add incoming edges for the PHI nodes
+ //
+ const std::vector<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB));
+
+ // Loop over all of the PHI nodes in the successor of BB.
+ for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ Value *OldVal = PN->removeIncomingValue(BB, false);
+ assert(OldVal && "No entry in PHI for Pred BB!");
+
+ // If this incoming value is one of the PHI nodes in BB, the new entries
+ // in the PHI node are the entries from the old PHI.
+ if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
+ PHINode *OldValPN = cast<PHINode>(OldVal);
+ for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i)
+ PN->addIncoming(OldValPN->getIncomingValue(i),
+ OldValPN->getIncomingBlock(i));
+ } else {
+ for (std::vector<BasicBlock*>::const_iterator PredI = BBPreds.begin(),
+ End = BBPreds.end(); PredI != End; ++PredI) {
+ // Add an incoming value for each of the new incoming values...
+ PN->addIncoming(OldVal, *PredI);
+ }
+ }
+ }
+ }
+
+ if (isa<PHINode>(&BB->front())) {
+ std::vector<BasicBlock*>
+ OldSuccPreds(pred_begin(Succ), pred_end(Succ));
+
+ // Move all PHI nodes in BB to Succ if they are alive, otherwise
+ // delete them.
+ while (PHINode *PN = dyn_cast<PHINode>(&BB->front()))
+ if (PN->use_empty()) {
+ // Just remove the dead phi. This happens if Succ's PHIs were the only
+ // users of the PHI nodes.
+ PN->eraseFromParent();
+ } else {
+ // The instruction is alive, so this means that Succ must have
+ // *ONLY* had BB as a predecessor, and the PHI node is still valid
+ // now. Simply move it into Succ, because we know that BB
+ // strictly dominated Succ.
+ Succ->getInstList().splice(Succ->begin(),
+ BB->getInstList(), BB->begin());
+
+ // We need to add new entries for the PHI node to account for
+ // predecessors of Succ that the PHI node does not take into
+ // account. At this point, since we know that BB dominated succ,
+ // this means that we should any newly added incoming edges should
+ // use the PHI node as the value for these edges, because they are
+ // loop back edges.
+ for (unsigned i = 0, e = OldSuccPreds.size(); i != e; ++i)
+ if (OldSuccPreds[i] != BB)
+ PN->addIncoming(PN, OldSuccPreds[i]);
+ }
+ }
+
+ // Everything that jumped to BB now goes to Succ.
+ BB->replaceAllUsesWith(Succ);
+ if (!Succ->hasName()) Succ->takeName(BB);
+ BB->eraseFromParent(); // Delete the old basic block.
+ return true;
+}
+
+/// GetIfCondition - Given a basic block (BB) with two predecessors (and
+/// presumably PHI nodes in it), check to see if the merge at this block is due
+/// to an "if condition". If so, return the boolean condition that determines
+/// which entry into BB will be taken. Also, return by references the block
+/// that will be entered from if the condition is true, and the block that will
+/// be entered if the condition is false.
+///
+///
+static Value *GetIfCondition(BasicBlock *BB,
+ BasicBlock *&IfTrue, BasicBlock *&IfFalse) {
+ assert(std::distance(pred_begin(BB), pred_end(BB)) == 2 &&
+ "Function can only handle blocks with 2 predecessors!");
+ BasicBlock *Pred1 = *pred_begin(BB);
+ BasicBlock *Pred2 = *++pred_begin(BB);
+
+ // We can only handle branches. Other control flow will be lowered to
+ // branches if possible anyway.
+ if (!isa<BranchInst>(Pred1->getTerminator()) ||
+ !isa<BranchInst>(Pred2->getTerminator()))
+ return 0;
+ BranchInst *Pred1Br = cast<BranchInst>(Pred1->getTerminator());
+ BranchInst *Pred2Br = cast<BranchInst>(Pred2->getTerminator());
+
+ // Eliminate code duplication by ensuring that Pred1Br is conditional if
+ // either are.
+ if (Pred2Br->isConditional()) {
+ // If both branches are conditional, we don't have an "if statement". In
+ // reality, we could transform this case, but since the condition will be
+ // required anyway, we stand no chance of eliminating it, so the xform is
+ // probably not profitable.
+ if (Pred1Br->isConditional())
+ return 0;
+
+ std::swap(Pred1, Pred2);
+ std::swap(Pred1Br, Pred2Br);
+ }
+
+ if (Pred1Br->isConditional()) {
+ // If we found a conditional branch predecessor, make sure that it branches
+ // to BB and Pred2Br. If it doesn't, this isn't an "if statement".
+ if (Pred1Br->getSuccessor(0) == BB &&
+ Pred1Br->getSuccessor(1) == Pred2) {
+ IfTrue = Pred1;
+ IfFalse = Pred2;
+ } else if (Pred1Br->getSuccessor(0) == Pred2 &&
+ Pred1Br->getSuccessor(1) == BB) {
+ IfTrue = Pred2;
+ IfFalse = Pred1;
+ } else {
+ // We know that one arm of the conditional goes to BB, so the other must
+ // go somewhere unrelated, and this must not be an "if statement".
+ return 0;
+ }
+
+ // The only thing we have to watch out for here is to make sure that Pred2
+ // doesn't have incoming edges from other blocks. If it does, the condition
+ // doesn't dominate BB.
+ if (++pred_begin(Pred2) != pred_end(Pred2))
+ return 0;
+
+ return Pred1Br->getCondition();
+ }
+
+ // Ok, if we got here, both predecessors end with an unconditional branch to
+ // BB. Don't panic! If both blocks only have a single (identical)
+ // predecessor, and THAT is a conditional branch, then we're all ok!
+ if (pred_begin(Pred1) == pred_end(Pred1) ||
+ ++pred_begin(Pred1) != pred_end(Pred1) ||
+ pred_begin(Pred2) == pred_end(Pred2) ||
+ ++pred_begin(Pred2) != pred_end(Pred2) ||
+ *pred_begin(Pred1) != *pred_begin(Pred2))
+ return 0;
+
+ // Otherwise, if this is a conditional branch, then we can use it!
+ BasicBlock *CommonPred = *pred_begin(Pred1);
+ if (BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator())) {
+ assert(BI->isConditional() && "Two successors but not conditional?");
+ if (BI->getSuccessor(0) == Pred1) {
+ IfTrue = Pred1;
+ IfFalse = Pred2;
+ } else {
+ IfTrue = Pred2;
+ IfFalse = Pred1;
+ }
+ return BI->getCondition();
+ }
+ return 0;
+}
+
+
+// If we have a merge point of an "if condition" as accepted above, return true
+// if the specified value dominates the block. We don't handle the true
+// generality of domination here, just a special case which works well enough
+// for us.
+//
+// If AggressiveInsts is non-null, and if V does not dominate BB, we check to
+// see if V (which must be an instruction) is cheap to compute and is
+// non-trapping. If both are true, the instruction is inserted into the set and
+// true is returned.
+static bool DominatesMergePoint(Value *V, BasicBlock *BB,
+ std::set<Instruction*> *AggressiveInsts) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) {
+ // Non-instructions all dominate instructions, but not all constantexprs
+ // can be executed unconditionally.
+ if (ConstantExpr *C = dyn_cast<ConstantExpr>(V))
+ if (C->canTrap())
+ return false;
+ return true;
+ }
+ BasicBlock *PBB = I->getParent();
+
+ // We don't want to allow weird loops that might have the "if condition" in
+ // the bottom of this block.
+ if (PBB == BB) return false;
+
+ // If this instruction is defined in a block that contains an unconditional
+ // branch to BB, then it must be in the 'conditional' part of the "if
+ // statement".
+ if (BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator()))
+ if (BI->isUnconditional() && BI->getSuccessor(0) == BB) {
+ if (!AggressiveInsts) return false;
+ // Okay, it looks like the instruction IS in the "condition". Check to
+ // see if its a cheap instruction to unconditionally compute, and if it
+ // only uses stuff defined outside of the condition. If so, hoist it out.
+ switch (I->getOpcode()) {
+ default: return false; // Cannot hoist this out safely.
+ case Instruction::Load:
+ // We can hoist loads that are non-volatile and obviously cannot trap.
+ if (cast<LoadInst>(I)->isVolatile())
+ return false;
+ if (!isa<AllocaInst>(I->getOperand(0)) &&
+ !isa<Constant>(I->getOperand(0)))
+ return false;
+
+ // Finally, we have to check to make sure there are no instructions
+ // before the load in its basic block, as we are going to hoist the loop
+ // out to its predecessor.
+ if (PBB->begin() != BasicBlock::iterator(I))
+ return false;
+ break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::ICmp:
+ case Instruction::FCmp:
+ break; // These are all cheap and non-trapping instructions.
+ }
+
+ // Okay, we can only really hoist these out if their operands are not
+ // defined in the conditional region.
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (!DominatesMergePoint(I->getOperand(i), BB, 0))
+ return false;
+ // Okay, it's safe to do this! Remember this instruction.
+ AggressiveInsts->insert(I);
+ }
+
+ return true;
+}
+
+// GatherConstantSetEQs - Given a potentially 'or'd together collection of
+// icmp_eq instructions that compare a value against a constant, return the
+// value being compared, and stick the constant into the Values vector.
+static Value *GatherConstantSetEQs(Value *V, std::vector<ConstantInt*> &Values){
+ if (Instruction *Inst = dyn_cast<Instruction>(V))
+ if (Inst->getOpcode() == Instruction::ICmp &&
+ cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_EQ) {
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(1))) {
+ Values.push_back(C);
+ return Inst->getOperand(0);
+ } else if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(0))) {
+ Values.push_back(C);
+ return Inst->getOperand(1);
+ }
+ } else if (Inst->getOpcode() == Instruction::Or) {
+ if (Value *LHS = GatherConstantSetEQs(Inst->getOperand(0), Values))
+ if (Value *RHS = GatherConstantSetEQs(Inst->getOperand(1), Values))
+ if (LHS == RHS)
+ return LHS;
+ }
+ return 0;
+}
+
+// GatherConstantSetNEs - Given a potentially 'and'd together collection of
+// setne instructions that compare a value against a constant, return the value
+// being compared, and stick the constant into the Values vector.
+static Value *GatherConstantSetNEs(Value *V, std::vector<ConstantInt*> &Values){
+ if (Instruction *Inst = dyn_cast<Instruction>(V))
+ if (Inst->getOpcode() == Instruction::ICmp &&
+ cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_NE) {
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(1))) {
+ Values.push_back(C);
+ return Inst->getOperand(0);
+ } else if (ConstantInt *C = dyn_cast<ConstantInt>(Inst->getOperand(0))) {
+ Values.push_back(C);
+ return Inst->getOperand(1);
+ }
+ } else if (Inst->getOpcode() == Instruction::And) {
+ if (Value *LHS = GatherConstantSetNEs(Inst->getOperand(0), Values))
+ if (Value *RHS = GatherConstantSetNEs(Inst->getOperand(1), Values))
+ if (LHS == RHS)
+ return LHS;
+ }
+ return 0;
+}
+
+
+
+/// GatherValueComparisons - If the specified Cond is an 'and' or 'or' of a
+/// bunch of comparisons of one value against constants, return the value and
+/// the constants being compared.
+static bool GatherValueComparisons(Instruction *Cond, Value *&CompVal,
+ std::vector<ConstantInt*> &Values) {
+ if (Cond->getOpcode() == Instruction::Or) {
+ CompVal = GatherConstantSetEQs(Cond, Values);
+
+ // Return true to indicate that the condition is true if the CompVal is
+ // equal to one of the constants.
+ return true;
+ } else if (Cond->getOpcode() == Instruction::And) {
+ CompVal = GatherConstantSetNEs(Cond, Values);
+
+ // Return false to indicate that the condition is false if the CompVal is
+ // equal to one of the constants.
+ return false;
+ }
+ return false;
+}
+
+/// ErasePossiblyDeadInstructionTree - If the specified instruction is dead and
+/// has no side effects, nuke it. If it uses any instructions that become dead
+/// because the instruction is now gone, nuke them too.
+static void ErasePossiblyDeadInstructionTree(Instruction *I) {
+ if (!isInstructionTriviallyDead(I)) return;
+
+ std::vector<Instruction*> InstrsToInspect;
+ InstrsToInspect.push_back(I);
+
+ while (!InstrsToInspect.empty()) {
+ I = InstrsToInspect.back();
+ InstrsToInspect.pop_back();
+
+ if (!isInstructionTriviallyDead(I)) continue;
+
+ // If I is in the work list multiple times, remove previous instances.
+ for (unsigned i = 0, e = InstrsToInspect.size(); i != e; ++i)
+ if (InstrsToInspect[i] == I) {
+ InstrsToInspect.erase(InstrsToInspect.begin()+i);
+ --i, --e;
+ }
+
+ // Add operands of dead instruction to worklist.
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
+ InstrsToInspect.push_back(OpI);
+
+ // Remove dead instruction.
+ I->eraseFromParent();
+ }
+}
+
+// isValueEqualityComparison - Return true if the specified terminator checks to
+// see if a value is equal to constant integer value.
+static Value *isValueEqualityComparison(TerminatorInst *TI) {
+ if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ // Do not permit merging of large switch instructions into their
+ // predecessors unless there is only one predecessor.
+ if (SI->getNumSuccessors() * std::distance(pred_begin(SI->getParent()),
+ pred_end(SI->getParent())) > 128)
+ return 0;
+
+ return SI->getCondition();
+ }
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI))
+ if (BI->isConditional() && BI->getCondition()->hasOneUse())
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
+ if ((ICI->getPredicate() == ICmpInst::ICMP_EQ ||
+ ICI->getPredicate() == ICmpInst::ICMP_NE) &&
+ isa<ConstantInt>(ICI->getOperand(1)))
+ return ICI->getOperand(0);
+ return 0;
+}
+
+// Given a value comparison instruction, decode all of the 'cases' that it
+// represents and return the 'default' block.
+static BasicBlock *
+GetValueEqualityComparisonCases(TerminatorInst *TI,
+ std::vector<std::pair<ConstantInt*,
+ BasicBlock*> > &Cases) {
+ if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ Cases.reserve(SI->getNumCases());
+ for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
+ Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i)));
+ return SI->getDefaultDest();
+ }
+
+ BranchInst *BI = cast<BranchInst>(TI);
+ ICmpInst *ICI = cast<ICmpInst>(BI->getCondition());
+ Cases.push_back(std::make_pair(cast<ConstantInt>(ICI->getOperand(1)),
+ BI->getSuccessor(ICI->getPredicate() ==
+ ICmpInst::ICMP_NE)));
+ return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ);
+}
+
+
+// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries
+// in the list that match the specified block.
+static void EliminateBlockCases(BasicBlock *BB,
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases) {
+ for (unsigned i = 0, e = Cases.size(); i != e; ++i)
+ if (Cases[i].second == BB) {
+ Cases.erase(Cases.begin()+i);
+ --i; --e;
+ }
+}
+
+// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as
+// well.
+static bool
+ValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1,
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) {
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2;
+
+ // Make V1 be smaller than V2.
+ if (V1->size() > V2->size())
+ std::swap(V1, V2);
+
+ if (V1->size() == 0) return false;
+ if (V1->size() == 1) {
+ // Just scan V2.
+ ConstantInt *TheVal = (*V1)[0].first;
+ for (unsigned i = 0, e = V2->size(); i != e; ++i)
+ if (TheVal == (*V2)[i].first)
+ return true;
+ }
+
+ // Otherwise, just sort both lists and compare element by element.
+ std::sort(V1->begin(), V1->end());
+ std::sort(V2->begin(), V2->end());
+ unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size();
+ while (i1 != e1 && i2 != e2) {
+ if ((*V1)[i1].first == (*V2)[i2].first)
+ return true;
+ if ((*V1)[i1].first < (*V2)[i2].first)
+ ++i1;
+ else
+ ++i2;
+ }
+ return false;
+}
+
+// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a
+// terminator instruction and its block is known to only have a single
+// predecessor block, check to see if that predecessor is also a value
+// comparison with the same value, and if that comparison determines the outcome
+// of this comparison. If so, simplify TI. This does a very limited form of
+// jump threading.
+static bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
+ BasicBlock *Pred) {
+ Value *PredVal = isValueEqualityComparison(Pred->getTerminator());
+ if (!PredVal) return false; // Not a value comparison in predecessor.
+
+ Value *ThisVal = isValueEqualityComparison(TI);
+ assert(ThisVal && "This isn't a value comparison!!");
+ if (ThisVal != PredVal) return false; // Different predicates.
+
+ // Find out information about when control will move from Pred to TI's block.
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases;
+ BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(),
+ PredCases);
+ EliminateBlockCases(PredDef, PredCases); // Remove default from cases.
+
+ // Find information about how control leaves this block.
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases;
+ BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases);
+ EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases.
+
+ // If TI's block is the default block from Pred's comparison, potentially
+ // simplify TI based on this knowledge.
+ if (PredDef == TI->getParent()) {
+ // If we are here, we know that the value is none of those cases listed in
+ // PredCases. If there are any cases in ThisCases that are in PredCases, we
+ // can simplify TI.
+ if (ValuesOverlap(PredCases, ThisCases)) {
+ if (BranchInst *BTI = dyn_cast<BranchInst>(TI)) {
+ // Okay, one of the successors of this condbr is dead. Convert it to a
+ // uncond br.
+ assert(ThisCases.size() == 1 && "Branch can only have one case!");
+ Value *Cond = BTI->getCondition();
+ // Insert the new branch.
+ Instruction *NI = new BranchInst(ThisDef, TI);
+
+ // Remove PHI node entries for the dead edge.
+ ThisCases[0].second->removePredecessor(TI->getParent());
+
+ DOUT << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n";
+
+ TI->eraseFromParent(); // Nuke the old one.
+ // If condition is now dead, nuke it.
+ if (Instruction *CondI = dyn_cast<Instruction>(Cond))
+ ErasePossiblyDeadInstructionTree(CondI);
+ return true;
+
+ } else {
+ SwitchInst *SI = cast<SwitchInst>(TI);
+ // Okay, TI has cases that are statically dead, prune them away.
+ SmallPtrSet<Constant*, 16> DeadCases;
+ for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
+ DeadCases.insert(PredCases[i].first);
+
+ DOUT << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI;
+
+ for (unsigned i = SI->getNumCases()-1; i != 0; --i)
+ if (DeadCases.count(SI->getCaseValue(i))) {
+ SI->getSuccessor(i)->removePredecessor(TI->getParent());
+ SI->removeCase(i);
+ }
+
+ DOUT << "Leaving: " << *TI << "\n";
+ return true;
+ }
+ }
+
+ } else {
+ // Otherwise, TI's block must correspond to some matched value. Find out
+ // which value (or set of values) this is.
+ ConstantInt *TIV = 0;
+ BasicBlock *TIBB = TI->getParent();
+ for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
+ if (PredCases[i].second == TIBB)
+ if (TIV == 0)
+ TIV = PredCases[i].first;
+ else
+ return false; // Cannot handle multiple values coming to this block.
+ assert(TIV && "No edge from pred to succ?");
+
+ // Okay, we found the one constant that our value can be if we get into TI's
+ // BB. Find out which successor will unconditionally be branched to.
+ BasicBlock *TheRealDest = 0;
+ for (unsigned i = 0, e = ThisCases.size(); i != e; ++i)
+ if (ThisCases[i].first == TIV) {
+ TheRealDest = ThisCases[i].second;
+ break;
+ }
+
+ // If not handled by any explicit cases, it is handled by the default case.
+ if (TheRealDest == 0) TheRealDest = ThisDef;
+
+ // Remove PHI node entries for dead edges.
+ BasicBlock *CheckEdge = TheRealDest;
+ for (succ_iterator SI = succ_begin(TIBB), e = succ_end(TIBB); SI != e; ++SI)
+ if (*SI != CheckEdge)
+ (*SI)->removePredecessor(TIBB);
+ else
+ CheckEdge = 0;
+
+ // Insert the new branch.
+ Instruction *NI = new BranchInst(TheRealDest, TI);
+
+ DOUT << "Threading pred instr: " << *Pred->getTerminator()
+ << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n";
+ Instruction *Cond = 0;
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI))
+ Cond = dyn_cast<Instruction>(BI->getCondition());
+ TI->eraseFromParent(); // Nuke the old one.
+
+ if (Cond) ErasePossiblyDeadInstructionTree(Cond);
+ return true;
+ }
+ return false;
+}
+
+// FoldValueComparisonIntoPredecessors - The specified terminator is a value
+// equality comparison instruction (either a switch or a branch on "X == c").
+// See if any of the predecessors of the terminator block are value comparisons
+// on the same value. If so, and if safe to do so, fold them together.
+static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
+ BasicBlock *BB = TI->getParent();
+ Value *CV = isValueEqualityComparison(TI); // CondVal
+ assert(CV && "Not a comparison?");
+ bool Changed = false;
+
+ std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ while (!Preds.empty()) {
+ BasicBlock *Pred = Preds.back();
+ Preds.pop_back();
+
+ // See if the predecessor is a comparison with the same value.
+ TerminatorInst *PTI = Pred->getTerminator();
+ Value *PCV = isValueEqualityComparison(PTI); // PredCondVal
+
+ if (PCV == CV && SafeToMergeTerminators(TI, PTI)) {
+ // Figure out which 'cases' to copy from SI to PSI.
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases;
+ BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases);
+
+ std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases;
+ BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases);
+
+ // Based on whether the default edge from PTI goes to BB or not, fill in
+ // PredCases and PredDefault with the new switch cases we would like to
+ // build.
+ std::vector<BasicBlock*> NewSuccessors;
+
+ if (PredDefault == BB) {
+ // If this is the default destination from PTI, only the edges in TI
+ // that don't occur in PTI, or that branch to BB will be activated.
+ std::set<ConstantInt*> PTIHandled;
+ for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
+ if (PredCases[i].second != BB)
+ PTIHandled.insert(PredCases[i].first);
+ else {
+ // The default destination is BB, we don't need explicit targets.
+ std::swap(PredCases[i], PredCases.back());
+ PredCases.pop_back();
+ --i; --e;
+ }
+
+ // Reconstruct the new switch statement we will be building.
+ if (PredDefault != BBDefault) {
+ PredDefault->removePredecessor(Pred);
+ PredDefault = BBDefault;
+ NewSuccessors.push_back(BBDefault);
+ }
+ for (unsigned i = 0, e = BBCases.size(); i != e; ++i)
+ if (!PTIHandled.count(BBCases[i].first) &&
+ BBCases[i].second != BBDefault) {
+ PredCases.push_back(BBCases[i]);
+ NewSuccessors.push_back(BBCases[i].second);
+ }
+
+ } else {
+ // If this is not the default destination from PSI, only the edges
+ // in SI that occur in PSI with a destination of BB will be
+ // activated.
+ std::set<ConstantInt*> PTIHandled;
+ for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
+ if (PredCases[i].second == BB) {
+ PTIHandled.insert(PredCases[i].first);
+ std::swap(PredCases[i], PredCases.back());
+ PredCases.pop_back();
+ --i; --e;
+ }
+
+ // Okay, now we know which constants were sent to BB from the
+ // predecessor. Figure out where they will all go now.
+ for (unsigned i = 0, e = BBCases.size(); i != e; ++i)
+ if (PTIHandled.count(BBCases[i].first)) {
+ // If this is one we are capable of getting...
+ PredCases.push_back(BBCases[i]);
+ NewSuccessors.push_back(BBCases[i].second);
+ PTIHandled.erase(BBCases[i].first);// This constant is taken care of
+ }
+
+ // If there are any constants vectored to BB that TI doesn't handle,
+ // they must go to the default destination of TI.
+ for (std::set<ConstantInt*>::iterator I = PTIHandled.begin(),
+ E = PTIHandled.end(); I != E; ++I) {
+ PredCases.push_back(std::make_pair(*I, BBDefault));
+ NewSuccessors.push_back(BBDefault);
+ }
+ }
+
+ // Okay, at this point, we know which new successor Pred will get. Make
+ // sure we update the number of entries in the PHI nodes for these
+ // successors.
+ for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i)
+ AddPredecessorToBlock(NewSuccessors[i], Pred, BB);
+
+ // Now that the successors are updated, create the new Switch instruction.
+ SwitchInst *NewSI = new SwitchInst(CV, PredDefault, PredCases.size(),PTI);
+ for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
+ NewSI->addCase(PredCases[i].first, PredCases[i].second);
+
+ Instruction *DeadCond = 0;
+ if (BranchInst *BI = dyn_cast<BranchInst>(PTI))
+ // If PTI is a branch, remember the condition.
+ DeadCond = dyn_cast<Instruction>(BI->getCondition());
+ Pred->getInstList().erase(PTI);
+
+ // If the condition is dead now, remove the instruction tree.
+ if (DeadCond) ErasePossiblyDeadInstructionTree(DeadCond);
+
+ // Okay, last check. If BB is still a successor of PSI, then we must
+ // have an infinite loop case. If so, add an infinitely looping block
+ // to handle the case to preserve the behavior of the code.
+ BasicBlock *InfLoopBlock = 0;
+ for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i)
+ if (NewSI->getSuccessor(i) == BB) {
+ if (InfLoopBlock == 0) {
+ // Insert it at the end of the loop, because it's either code,
+ // or it won't matter if it's hot. :)
+ InfLoopBlock = new BasicBlock("infloop", BB->getParent());
+ new BranchInst(InfLoopBlock, InfLoopBlock);
+ }
+ NewSI->setSuccessor(i, InfLoopBlock);
+ }
+
+ Changed = true;
+ }
+ }
+ return Changed;
+}
+
+/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and
+/// BB2, hoist any common code in the two blocks up into the branch block. The
+/// caller of this function guarantees that BI's block dominates BB1 and BB2.
+static bool HoistThenElseCodeToIf(BranchInst *BI) {
+ // This does very trivial matching, with limited scanning, to find identical
+ // instructions in the two blocks. In particular, we don't want to get into
+ // O(M*N) situations here where M and N are the sizes of BB1 and BB2. As
+ // such, we currently just scan for obviously identical instructions in an
+ // identical order.
+ BasicBlock *BB1 = BI->getSuccessor(0); // The true destination.
+ BasicBlock *BB2 = BI->getSuccessor(1); // The false destination
+
+ Instruction *I1 = BB1->begin(), *I2 = BB2->begin();
+ if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
+ isa<InvokeInst>(I1) || !I1->isIdenticalTo(I2))
+ return false;
+
+ // If we get here, we can hoist at least one instruction.
+ BasicBlock *BIParent = BI->getParent();
+
+ do {
+ // If we are hoisting the terminator instruction, don't move one (making a
+ // broken BB), instead clone it, and remove BI.
+ if (isa<TerminatorInst>(I1))
+ goto HoistTerminator;
+
+ // For a normal instruction, we just move one to right before the branch,
+ // then replace all uses of the other with the first. Finally, we remove
+ // the now redundant second instruction.
+ BIParent->getInstList().splice(BI, BB1->getInstList(), I1);
+ if (!I2->use_empty())
+ I2->replaceAllUsesWith(I1);
+ BB2->getInstList().erase(I2);
+
+ I1 = BB1->begin();
+ I2 = BB2->begin();
+ } while (I1->getOpcode() == I2->getOpcode() && I1->isIdenticalTo(I2));
+
+ return true;
+
+HoistTerminator:
+ // Okay, it is safe to hoist the terminator.
+ Instruction *NT = I1->clone();
+ BIParent->getInstList().insert(BI, NT);
+ if (NT->getType() != Type::VoidTy) {
+ I1->replaceAllUsesWith(NT);
+ I2->replaceAllUsesWith(NT);
+ NT->takeName(I1);
+ }
+
+ // Hoisting one of the terminators from our successor is a great thing.
+ // Unfortunately, the successors of the if/else blocks may have PHI nodes in
+ // them. If they do, all PHI entries for BB1/BB2 must agree for all PHI
+ // nodes, so we insert select instruction to compute the final result.
+ std::map<std::pair<Value*,Value*>, SelectInst*> InsertedSelects;
+ for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) {
+ PHINode *PN;
+ for (BasicBlock::iterator BBI = SI->begin();
+ (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+ Value *BB1V = PN->getIncomingValueForBlock(BB1);
+ Value *BB2V = PN->getIncomingValueForBlock(BB2);
+ if (BB1V != BB2V) {
+ // These values do not agree. Insert a select instruction before NT
+ // that determines the right value.
+ SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)];
+ if (SI == 0)
+ SI = new SelectInst(BI->getCondition(), BB1V, BB2V,
+ BB1V->getName()+"."+BB2V->getName(), NT);
+ // Make the PHI node use the select for all incoming values for BB1/BB2
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2)
+ PN->setIncomingValue(i, SI);
+ }
+ }
+ }
+
+ // Update any PHI nodes in our new successors.
+ for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI)
+ AddPredecessorToBlock(*SI, BIParent, BB1);
+
+ BI->eraseFromParent();
+ return true;
+}
+
+/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch
+/// across this block.
+static bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) {
+ BranchInst *BI = cast<BranchInst>(BB->getTerminator());
+ unsigned Size = 0;
+
+ // If this basic block contains anything other than a PHI (which controls the
+ // branch) and branch itself, bail out. FIXME: improve this in the future.
+ for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI, ++Size) {
+ if (Size > 10) return false; // Don't clone large BB's.
+
+ // We can only support instructions that are do not define values that are
+ // live outside of the current basic block.
+ for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end();
+ UI != E; ++UI) {
+ Instruction *U = cast<Instruction>(*UI);
+ if (U->getParent() != BB || isa<PHINode>(U)) return false;
+ }
+
+ // Looks ok, continue checking.
+ }
+
+ return true;
+}
+
+/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value
+/// that is defined in the same block as the branch and if any PHI entries are
+/// constants, thread edges corresponding to that entry to be branches to their
+/// ultimate destination.
+static bool FoldCondBranchOnPHI(BranchInst *BI) {
+ BasicBlock *BB = BI->getParent();
+ PHINode *PN = dyn_cast<PHINode>(BI->getCondition());
+ // NOTE: we currently cannot transform this case if the PHI node is used
+ // outside of the block.
+ if (!PN || PN->getParent() != BB || !PN->hasOneUse())
+ return false;
+
+ // Degenerate case of a single entry PHI.
+ if (PN->getNumIncomingValues() == 1) {
+ if (PN->getIncomingValue(0) != PN)
+ PN->replaceAllUsesWith(PN->getIncomingValue(0));
+ else
+ PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+ PN->eraseFromParent();
+ return true;
+ }
+
+ // Now we know that this block has multiple preds and two succs.
+ if (!BlockIsSimpleEnoughToThreadThrough(BB)) return false;
+
+ // Okay, this is a simple enough basic block. See if any phi values are
+ // constants.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ ConstantInt *CB;
+ if ((CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i))) &&
+ CB->getType() == Type::Int1Ty) {
+ // Okay, we now know that all edges from PredBB should be revectored to
+ // branch to RealDest.
+ BasicBlock *PredBB = PN->getIncomingBlock(i);
+ BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue());
+
+ if (RealDest == BB) continue; // Skip self loops.
+
+ // The dest block might have PHI nodes, other predecessors and other
+ // difficult cases. Instead of being smart about this, just insert a new
+ // block that jumps to the destination block, effectively splitting
+ // the edge we are about to create.
+ BasicBlock *EdgeBB = new BasicBlock(RealDest->getName()+".critedge",
+ RealDest->getParent(), RealDest);
+ new BranchInst(RealDest, EdgeBB);
+ PHINode *PN;
+ for (BasicBlock::iterator BBI = RealDest->begin();
+ (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+ Value *V = PN->getIncomingValueForBlock(BB);
+ PN->addIncoming(V, EdgeBB);
+ }
+
+ // BB may have instructions that are being threaded over. Clone these
+ // instructions into EdgeBB. We know that there will be no uses of the
+ // cloned instructions outside of EdgeBB.
+ BasicBlock::iterator InsertPt = EdgeBB->begin();
+ std::map<Value*, Value*> TranslateMap; // Track translated values.
+ for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) {
+ if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
+ TranslateMap[PN] = PN->getIncomingValueForBlock(PredBB);
+ } else {
+ // Clone the instruction.
+ Instruction *N = BBI->clone();
+ if (BBI->hasName()) N->setName(BBI->getName()+".c");
+
+ // Update operands due to translation.
+ for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+ std::map<Value*, Value*>::iterator PI =
+ TranslateMap.find(N->getOperand(i));
+ if (PI != TranslateMap.end())
+ N->setOperand(i, PI->second);
+ }
+
+ // Check for trivial simplification.
+ if (Constant *C = ConstantFoldInstruction(N)) {
+ TranslateMap[BBI] = C;
+ delete N; // Constant folded away, don't need actual inst
+ } else {
+ // Insert the new instruction into its new home.
+ EdgeBB->getInstList().insert(InsertPt, N);
+ if (!BBI->use_empty())
+ TranslateMap[BBI] = N;
+ }
+ }
+ }
+
+ // Loop over all of the edges from PredBB to BB, changing them to branch
+ // to EdgeBB instead.
+ TerminatorInst *PredBBTI = PredBB->getTerminator();
+ for (unsigned i = 0, e = PredBBTI->getNumSuccessors(); i != e; ++i)
+ if (PredBBTI->getSuccessor(i) == BB) {
+ BB->removePredecessor(PredBB);
+ PredBBTI->setSuccessor(i, EdgeBB);
+ }
+
+ // Recurse, simplifying any other constants.
+ return FoldCondBranchOnPHI(BI) | true;
+ }
+ }
+
+ return false;
+}
+
+/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry
+/// PHI node, see if we can eliminate it.
+static bool FoldTwoEntryPHINode(PHINode *PN) {
+ // Ok, this is a two entry PHI node. Check to see if this is a simple "if
+ // statement", which has a very simple dominance structure. Basically, we
+ // are trying to find the condition that is being branched on, which
+ // subsequently causes this merge to happen. We really want control
+ // dependence information for this check, but simplifycfg can't keep it up
+ // to date, and this catches most of the cases we care about anyway.
+ //
+ BasicBlock *BB = PN->getParent();
+ BasicBlock *IfTrue, *IfFalse;
+ Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse);
+ if (!IfCond) return false;
+
+ // Okay, we found that we can merge this two-entry phi node into a select.
+ // Doing so would require us to fold *all* two entry phi nodes in this block.
+ // At some point this becomes non-profitable (particularly if the target
+ // doesn't support cmov's). Only do this transformation if there are two or
+ // fewer PHI nodes in this block.
+ unsigned NumPhis = 0;
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++NumPhis, ++I)
+ if (NumPhis > 2)
+ return false;
+
+ DOUT << "FOUND IF CONDITION! " << *IfCond << " T: "
+ << IfTrue->getName() << " F: " << IfFalse->getName() << "\n";
+
+ // Loop over the PHI's seeing if we can promote them all to select
+ // instructions. While we are at it, keep track of the instructions
+ // that need to be moved to the dominating block.
+ std::set<Instruction*> AggressiveInsts;
+
+ BasicBlock::iterator AfterPHIIt = BB->begin();
+ while (isa<PHINode>(AfterPHIIt)) {
+ PHINode *PN = cast<PHINode>(AfterPHIIt++);
+ if (PN->getIncomingValue(0) == PN->getIncomingValue(1)) {
+ if (PN->getIncomingValue(0) != PN)
+ PN->replaceAllUsesWith(PN->getIncomingValue(0));
+ else
+ PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+ } else if (!DominatesMergePoint(PN->getIncomingValue(0), BB,
+ &AggressiveInsts) ||
+ !DominatesMergePoint(PN->getIncomingValue(1), BB,
+ &AggressiveInsts)) {
+ return false;
+ }
+ }
+
+ // If we all PHI nodes are promotable, check to make sure that all
+ // instructions in the predecessor blocks can be promoted as well. If
+ // not, we won't be able to get rid of the control flow, so it's not
+ // worth promoting to select instructions.
+ BasicBlock *DomBlock = 0, *IfBlock1 = 0, *IfBlock2 = 0;
+ PN = cast<PHINode>(BB->begin());
+ BasicBlock *Pred = PN->getIncomingBlock(0);
+ if (cast<BranchInst>(Pred->getTerminator())->isUnconditional()) {
+ IfBlock1 = Pred;
+ DomBlock = *pred_begin(Pred);
+ for (BasicBlock::iterator I = Pred->begin();
+ !isa<TerminatorInst>(I); ++I)
+ if (!AggressiveInsts.count(I)) {
+ // This is not an aggressive instruction that we can promote.
+ // Because of this, we won't be able to get rid of the control
+ // flow, so the xform is not worth it.
+ return false;
+ }
+ }
+
+ Pred = PN->getIncomingBlock(1);
+ if (cast<BranchInst>(Pred->getTerminator())->isUnconditional()) {
+ IfBlock2 = Pred;
+ DomBlock = *pred_begin(Pred);
+ for (BasicBlock::iterator I = Pred->begin();
+ !isa<TerminatorInst>(I); ++I)
+ if (!AggressiveInsts.count(I)) {
+ // This is not an aggressive instruction that we can promote.
+ // Because of this, we won't be able to get rid of the control
+ // flow, so the xform is not worth it.
+ return false;
+ }
+ }
+
+ // If we can still promote the PHI nodes after this gauntlet of tests,
+ // do all of the PHI's now.
+
+ // Move all 'aggressive' instructions, which are defined in the
+ // conditional parts of the if's up to the dominating block.
+ if (IfBlock1) {
+ DomBlock->getInstList().splice(DomBlock->getTerminator(),
+ IfBlock1->getInstList(),
+ IfBlock1->begin(),
+ IfBlock1->getTerminator());
+ }
+ if (IfBlock2) {
+ DomBlock->getInstList().splice(DomBlock->getTerminator(),
+ IfBlock2->getInstList(),
+ IfBlock2->begin(),
+ IfBlock2->getTerminator());
+ }
+
+ while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
+ // Change the PHI node into a select instruction.
+ Value *TrueVal =
+ PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse);
+ Value *FalseVal =
+ PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue);
+
+ Value *NV = new SelectInst(IfCond, TrueVal, FalseVal, "", AfterPHIIt);
+ PN->replaceAllUsesWith(NV);
+ NV->takeName(PN);
+
+ BB->getInstList().erase(PN);
+ }
+ return true;
+}
+
+namespace {
+ /// ConstantIntOrdering - This class implements a stable ordering of constant
+ /// integers that does not depend on their address. This is important for
+ /// applications that sort ConstantInt's to ensure uniqueness.
+ struct ConstantIntOrdering {
+ bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const {
+ return LHS->getValue().ult(RHS->getValue());
+ }
+ };
+}
+
+// SimplifyCFG - This function is used to do simplification of a CFG. For
+// example, it adjusts branches to branches to eliminate the extra hop, it
+// eliminates unreachable basic blocks, and does other "peephole" optimization
+// of the CFG. It returns true if a modification was made.
+//
+// WARNING: The entry node of a function may not be simplified.
+//
+bool llvm::SimplifyCFG(BasicBlock *BB) {
+ bool Changed = false;
+ Function *M = BB->getParent();
+
+ assert(BB && BB->getParent() && "Block not embedded in function!");
+ assert(BB->getTerminator() && "Degenerate basic block encountered!");
+ assert(&BB->getParent()->getEntryBlock() != BB &&
+ "Can't Simplify entry block!");
+
+ // Remove basic blocks that have no predecessors... which are unreachable.
+ if (pred_begin(BB) == pred_end(BB) ||
+ *pred_begin(BB) == BB && ++pred_begin(BB) == pred_end(BB)) {
+ DOUT << "Removing BB: \n" << *BB;
+
+ // Loop through all of our successors and make sure they know that one
+ // of their predecessors is going away.
+ for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
+ SI->removePredecessor(BB);
+
+ while (!BB->empty()) {
+ Instruction &I = BB->back();
+ // If this instruction is used, replace uses with an arbitrary
+ // value. Because control flow can't get here, we don't care
+ // what we replace the value with. Note that since this block is
+ // unreachable, and all values contained within it must dominate their
+ // uses, that all uses will eventually be removed.
+ if (!I.use_empty())
+ // Make all users of this instruction use undef instead
+ I.replaceAllUsesWith(UndefValue::get(I.getType()));
+
+ // Remove the instruction from the basic block
+ BB->getInstList().pop_back();
+ }
+ M->getBasicBlockList().erase(BB);
+ return true;
+ }
+
+ // Check to see if we can constant propagate this terminator instruction
+ // away...
+ Changed |= ConstantFoldTerminator(BB);
+
+ // If this is a returning block with only PHI nodes in it, fold the return
+ // instruction into any unconditional branch predecessors.
+ //
+ // If any predecessor is a conditional branch that just selects among
+ // different return values, fold the replace the branch/return with a select
+ // and return.
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
+ BasicBlock::iterator BBI = BB->getTerminator();
+ if (BBI == BB->begin() || isa<PHINode>(--BBI)) {
+ // Find predecessors that end with branches.
+ std::vector<BasicBlock*> UncondBranchPreds;
+ std::vector<BranchInst*> CondBranchPreds;
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
+ TerminatorInst *PTI = (*PI)->getTerminator();
+ if (BranchInst *BI = dyn_cast<BranchInst>(PTI))
+ if (BI->isUnconditional())
+ UncondBranchPreds.push_back(*PI);
+ else
+ CondBranchPreds.push_back(BI);
+ }
+
+ // If we found some, do the transformation!
+ if (!UncondBranchPreds.empty()) {
+ while (!UncondBranchPreds.empty()) {
+ BasicBlock *Pred = UncondBranchPreds.back();
+ DOUT << "FOLDING: " << *BB
+ << "INTO UNCOND BRANCH PRED: " << *Pred;
+ UncondBranchPreds.pop_back();
+ Instruction *UncondBranch = Pred->getTerminator();
+ // Clone the return and add it to the end of the predecessor.
+ Instruction *NewRet = RI->clone();
+ Pred->getInstList().push_back(NewRet);
+
+ // If the return instruction returns a value, and if the value was a
+ // PHI node in "BB", propagate the right value into the return.
+ if (NewRet->getNumOperands() == 1)
+ if (PHINode *PN = dyn_cast<PHINode>(NewRet->getOperand(0)))
+ if (PN->getParent() == BB)
+ NewRet->setOperand(0, PN->getIncomingValueForBlock(Pred));
+ // Update any PHI nodes in the returning block to realize that we no
+ // longer branch to them.
+ BB->removePredecessor(Pred);
+ Pred->getInstList().erase(UncondBranch);
+ }
+
+ // If we eliminated all predecessors of the block, delete the block now.
+ if (pred_begin(BB) == pred_end(BB))
+ // We know there are no successors, so just nuke the block.
+ M->getBasicBlockList().erase(BB);
+
+ return true;
+ }
+
+ // Check out all of the conditional branches going to this return
+ // instruction. If any of them just select between returns, change the
+ // branch itself into a select/return pair.
+ while (!CondBranchPreds.empty()) {
+ BranchInst *BI = CondBranchPreds.back();
+ CondBranchPreds.pop_back();
+ BasicBlock *TrueSucc = BI->getSuccessor(0);
+ BasicBlock *FalseSucc = BI->getSuccessor(1);
+ BasicBlock *OtherSucc = TrueSucc == BB ? FalseSucc : TrueSucc;
+
+ // Check to see if the non-BB successor is also a return block.
+ if (isa<ReturnInst>(OtherSucc->getTerminator())) {
+ // Check to see if there are only PHI instructions in this block.
+ BasicBlock::iterator OSI = OtherSucc->getTerminator();
+ if (OSI == OtherSucc->begin() || isa<PHINode>(--OSI)) {
+ // Okay, we found a branch that is going to two return nodes. If
+ // there is no return value for this function, just change the
+ // branch into a return.
+ if (RI->getNumOperands() == 0) {
+ TrueSucc->removePredecessor(BI->getParent());
+ FalseSucc->removePredecessor(BI->getParent());
+ new ReturnInst(0, BI);
+ BI->getParent()->getInstList().erase(BI);
+ return true;
+ }
+
+ // Otherwise, figure out what the true and false return values are
+ // so we can insert a new select instruction.
+ Value *TrueValue = TrueSucc->getTerminator()->getOperand(0);
+ Value *FalseValue = FalseSucc->getTerminator()->getOperand(0);
+
+ // Unwrap any PHI nodes in the return blocks.
+ if (PHINode *TVPN = dyn_cast<PHINode>(TrueValue))
+ if (TVPN->getParent() == TrueSucc)
+ TrueValue = TVPN->getIncomingValueForBlock(BI->getParent());
+ if (PHINode *FVPN = dyn_cast<PHINode>(FalseValue))
+ if (FVPN->getParent() == FalseSucc)
+ FalseValue = FVPN->getIncomingValueForBlock(BI->getParent());
+
+ // In order for this transformation to be safe, we must be able to
+ // unconditionally execute both operands to the return. This is
+ // normally the case, but we could have a potentially-trapping
+ // constant expression that prevents this transformation from being
+ // safe.
+ if ((!isa<ConstantExpr>(TrueValue) ||
+ !cast<ConstantExpr>(TrueValue)->canTrap()) &&
+ (!isa<ConstantExpr>(TrueValue) ||
+ !cast<ConstantExpr>(TrueValue)->canTrap())) {
+ TrueSucc->removePredecessor(BI->getParent());
+ FalseSucc->removePredecessor(BI->getParent());
+
+ // Insert a new select instruction.
+ Value *NewRetVal;
+ Value *BrCond = BI->getCondition();
+ if (TrueValue != FalseValue)
+ NewRetVal = new SelectInst(BrCond, TrueValue,
+ FalseValue, "retval", BI);
+ else
+ NewRetVal = TrueValue;
+
+ DOUT << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:"
+ << "\n " << *BI << "Select = " << *NewRetVal
+ << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc;
+
+ new ReturnInst(NewRetVal, BI);
+ BI->eraseFromParent();
+ if (Instruction *BrCondI = dyn_cast<Instruction>(BrCond))
+ if (isInstructionTriviallyDead(BrCondI))
+ BrCondI->eraseFromParent();
+ return true;
+ }
+ }
+ }
+ }
+ }
+ } else if (isa<UnwindInst>(BB->begin())) {
+ // Check to see if the first instruction in this block is just an unwind.
+ // If so, replace any invoke instructions which use this as an exception
+ // destination with call instructions, and any unconditional branch
+ // predecessor with an unwind.
+ //
+ std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ while (!Preds.empty()) {
+ BasicBlock *Pred = Preds.back();
+ if (BranchInst *BI = dyn_cast<BranchInst>(Pred->getTerminator())) {
+ if (BI->isUnconditional()) {
+ Pred->getInstList().pop_back(); // nuke uncond branch
+ new UnwindInst(Pred); // Use unwind.
+ Changed = true;
+ }
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
+ if (II->getUnwindDest() == BB) {
+ // Insert a new branch instruction before the invoke, because this
+ // is now a fall through...
+ BranchInst *BI = new BranchInst(II->getNormalDest(), II);
+ Pred->getInstList().remove(II); // Take out of symbol table
+
+ // Insert the call now...
+ SmallVector<Value*,8> Args(II->op_begin()+3, II->op_end());
+ CallInst *CI = new CallInst(II->getCalledValue(),
+ &Args[0], Args.size(), II->getName(), BI);
+ CI->setCallingConv(II->getCallingConv());
+ // If the invoke produced a value, the Call now does instead
+ II->replaceAllUsesWith(CI);
+ delete II;
+ Changed = true;
+ }
+
+ Preds.pop_back();
+ }
+
+ // If this block is now dead, remove it.
+ if (pred_begin(BB) == pred_end(BB)) {
+ // We know there are no successors, so just nuke the block.
+ M->getBasicBlockList().erase(BB);
+ return true;
+ }
+
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
+ if (isValueEqualityComparison(SI)) {
+ // If we only have one predecessor, and if it is a branch on this value,
+ // see if that predecessor totally determines the outcome of this switch.
+ if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
+ if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred))
+ return SimplifyCFG(BB) || 1;
+
+ // If the block only contains the switch, see if we can fold the block
+ // away into any preds.
+ if (SI == &BB->front())
+ if (FoldValueComparisonIntoPredecessors(SI))
+ return SimplifyCFG(BB) || 1;
+ }
+ } else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
+ if (BI->isUnconditional()) {
+ BasicBlock::iterator BBI = BB->begin(); // Skip over phi nodes...
+ while (isa<PHINode>(*BBI)) ++BBI;
+
+ BasicBlock *Succ = BI->getSuccessor(0);
+ if (BBI->isTerminator() && // Terminator is the only non-phi instruction!
+ Succ != BB) // Don't hurt infinite loops!
+ if (TryToSimplifyUncondBranchFromEmptyBlock(BB, Succ))
+ return 1;
+
+ } else { // Conditional branch
+ if (isValueEqualityComparison(BI)) {
+ // If we only have one predecessor, and if it is a branch on this value,
+ // see if that predecessor totally determines the outcome of this
+ // switch.
+ if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
+ if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred))
+ return SimplifyCFG(BB) || 1;
+
+ // This block must be empty, except for the setcond inst, if it exists.
+ BasicBlock::iterator I = BB->begin();
+ if (&*I == BI ||
+ (&*I == cast<Instruction>(BI->getCondition()) &&
+ &*++I == BI))
+ if (FoldValueComparisonIntoPredecessors(BI))
+ return SimplifyCFG(BB) | true;
+ }
+
+ // If this is a branch on a phi node in the current block, thread control
+ // through this block if any PHI node entries are constants.
+ if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition()))
+ if (PN->getParent() == BI->getParent())
+ if (FoldCondBranchOnPHI(BI))
+ return SimplifyCFG(BB) | true;
+
+ // If this basic block is ONLY a setcc and a branch, and if a predecessor
+ // branches to us and one of our successors, fold the setcc into the
+ // predecessor and use logical operations to pick the right destination.
+ BasicBlock *TrueDest = BI->getSuccessor(0);
+ BasicBlock *FalseDest = BI->getSuccessor(1);
+ if (Instruction *Cond = dyn_cast<Instruction>(BI->getCondition())) {
+ BasicBlock::iterator CondIt = Cond;
+ if ((isa<CmpInst>(Cond) || isa<BinaryOperator>(Cond)) &&
+ Cond->getParent() == BB && &BB->front() == Cond &&
+ &*++CondIt == BI && Cond->hasOneUse() &&
+ TrueDest != BB && FalseDest != BB)
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI!=E; ++PI)
+ if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator()))
+ if (PBI->isConditional() && SafeToMergeTerminators(BI, PBI)) {
+ BasicBlock *PredBlock = *PI;
+ if (PBI->getSuccessor(0) == FalseDest ||
+ PBI->getSuccessor(1) == TrueDest) {
+ // Invert the predecessors condition test (xor it with true),
+ // which allows us to write this code once.
+ Value *NewCond =
+ BinaryOperator::createNot(PBI->getCondition(),
+ PBI->getCondition()->getName()+".not", PBI);
+ PBI->setCondition(NewCond);
+ BasicBlock *OldTrue = PBI->getSuccessor(0);
+ BasicBlock *OldFalse = PBI->getSuccessor(1);
+ PBI->setSuccessor(0, OldFalse);
+ PBI->setSuccessor(1, OldTrue);
+ }
+
+ if ((PBI->getSuccessor(0) == TrueDest && FalseDest != BB) ||
+ (PBI->getSuccessor(1) == FalseDest && TrueDest != BB)) {
+ // Clone Cond into the predecessor basic block, and or/and the
+ // two conditions together.
+ Instruction *New = Cond->clone();
+ PredBlock->getInstList().insert(PBI, New);
+ New->takeName(Cond);
+ Cond->setName(New->getName()+".old");
+ Instruction::BinaryOps Opcode =
+ PBI->getSuccessor(0) == TrueDest ?
+ Instruction::Or : Instruction::And;
+ Value *NewCond =
+ BinaryOperator::create(Opcode, PBI->getCondition(),
+ New, "bothcond", PBI);
+ PBI->setCondition(NewCond);
+ if (PBI->getSuccessor(0) == BB) {
+ AddPredecessorToBlock(TrueDest, PredBlock, BB);
+ PBI->setSuccessor(0, TrueDest);
+ }
+ if (PBI->getSuccessor(1) == BB) {
+ AddPredecessorToBlock(FalseDest, PredBlock, BB);
+ PBI->setSuccessor(1, FalseDest);
+ }
+ return SimplifyCFG(BB) | 1;
+ }
+ }
+ }
+
+ // Scan predessor blocks for conditional branches.
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator()))
+ if (PBI != BI && PBI->isConditional()) {
+
+ // If this block ends with a branch instruction, and if there is a
+ // predecessor that ends on a branch of the same condition, make
+ // this conditional branch redundant.
+ if (PBI->getCondition() == BI->getCondition() &&
+ PBI->getSuccessor(0) != PBI->getSuccessor(1)) {
+ // Okay, the outcome of this conditional branch is statically
+ // knowable. If this block had a single pred, handle specially.
+ if (BB->getSinglePredecessor()) {
+ // Turn this into a branch on constant.
+ bool CondIsTrue = PBI->getSuccessor(0) == BB;
+ BI->setCondition(ConstantInt::get(Type::Int1Ty, CondIsTrue));
+ return SimplifyCFG(BB); // Nuke the branch on constant.
+ }
+
+ // Otherwise, if there are multiple predecessors, insert a PHI
+ // that merges in the constant and simplify the block result.
+ if (BlockIsSimpleEnoughToThreadThrough(BB)) {
+ PHINode *NewPN = new PHINode(Type::Int1Ty,
+ BI->getCondition()->getName()+".pr",
+ BB->begin());
+ for (PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ if ((PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) &&
+ PBI != BI && PBI->isConditional() &&
+ PBI->getCondition() == BI->getCondition() &&
+ PBI->getSuccessor(0) != PBI->getSuccessor(1)) {
+ bool CondIsTrue = PBI->getSuccessor(0) == BB;
+ NewPN->addIncoming(ConstantInt::get(Type::Int1Ty,
+ CondIsTrue), *PI);
+ } else {
+ NewPN->addIncoming(BI->getCondition(), *PI);
+ }
+
+ BI->setCondition(NewPN);
+ // This will thread the branch.
+ return SimplifyCFG(BB) | true;
+ }
+ }
+
+ // If this is a conditional branch in an empty block, and if any
+ // predecessors is a conditional branch to one of our destinations,
+ // fold the conditions into logical ops and one cond br.
+ if (&BB->front() == BI) {
+ int PBIOp, BIOp;
+ if (PBI->getSuccessor(0) == BI->getSuccessor(0)) {
+ PBIOp = BIOp = 0;
+ } else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) {
+ PBIOp = 0; BIOp = 1;
+ } else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) {
+ PBIOp = 1; BIOp = 0;
+ } else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) {
+ PBIOp = BIOp = 1;
+ } else {
+ PBIOp = BIOp = -1;
+ }
+
+ // Check to make sure that the other destination of this branch
+ // isn't BB itself. If so, this is an infinite loop that will
+ // keep getting unwound.
+ if (PBIOp != -1 && PBI->getSuccessor(PBIOp) == BB)
+ PBIOp = BIOp = -1;
+
+ // Do not perform this transformation if it would require
+ // insertion of a large number of select instructions. For targets
+ // without predication/cmovs, this is a big pessimization.
+ if (PBIOp != -1) {
+ BasicBlock *CommonDest = PBI->getSuccessor(PBIOp);
+
+ unsigned NumPhis = 0;
+ for (BasicBlock::iterator II = CommonDest->begin();
+ isa<PHINode>(II); ++II, ++NumPhis) {
+ if (NumPhis > 2) {
+ // Disable this xform.
+ PBIOp = -1;
+ break;
+ }
+ }
+ }
+
+ // Finally, if everything is ok, fold the branches to logical ops.
+ if (PBIOp != -1) {
+ BasicBlock *CommonDest = PBI->getSuccessor(PBIOp);
+ BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1);
+
+ // If OtherDest *is* BB, then this is a basic block with just
+ // a conditional branch in it, where one edge (OtherDesg) goes
+ // back to the block. We know that the program doesn't get
+ // stuck in the infinite loop, so the condition must be such
+ // that OtherDest isn't branched through. Forward to CommonDest,
+ // and avoid an infinite loop at optimizer time.
+ if (OtherDest == BB)
+ OtherDest = CommonDest;
+
+ DOUT << "FOLDING BRs:" << *PBI->getParent()
+ << "AND: " << *BI->getParent();
+
+ // BI may have other predecessors. Because of this, we leave
+ // it alone, but modify PBI.
+
+ // Make sure we get to CommonDest on True&True directions.
+ Value *PBICond = PBI->getCondition();
+ if (PBIOp)
+ PBICond = BinaryOperator::createNot(PBICond,
+ PBICond->getName()+".not",
+ PBI);
+ Value *BICond = BI->getCondition();
+ if (BIOp)
+ BICond = BinaryOperator::createNot(BICond,
+ BICond->getName()+".not",
+ PBI);
+ // Merge the conditions.
+ Value *Cond =
+ BinaryOperator::createOr(PBICond, BICond, "brmerge", PBI);
+
+ // Modify PBI to branch on the new condition to the new dests.
+ PBI->setCondition(Cond);
+ PBI->setSuccessor(0, CommonDest);
+ PBI->setSuccessor(1, OtherDest);
+
+ // OtherDest may have phi nodes. If so, add an entry from PBI's
+ // block that are identical to the entries for BI's block.
+ PHINode *PN;
+ for (BasicBlock::iterator II = OtherDest->begin();
+ (PN = dyn_cast<PHINode>(II)); ++II) {
+ Value *V = PN->getIncomingValueForBlock(BB);
+ PN->addIncoming(V, PBI->getParent());
+ }
+
+ // We know that the CommonDest already had an edge from PBI to
+ // it. If it has PHIs though, the PHIs may have different
+ // entries for BB and PBI's BB. If so, insert a select to make
+ // them agree.
+ for (BasicBlock::iterator II = CommonDest->begin();
+ (PN = dyn_cast<PHINode>(II)); ++II) {
+ Value * BIV = PN->getIncomingValueForBlock(BB);
+ unsigned PBBIdx = PN->getBasicBlockIndex(PBI->getParent());
+ Value *PBIV = PN->getIncomingValue(PBBIdx);
+ if (BIV != PBIV) {
+ // Insert a select in PBI to pick the right value.
+ Value *NV = new SelectInst(PBICond, PBIV, BIV,
+ PBIV->getName()+".mux", PBI);
+ PN->setIncomingValue(PBBIdx, NV);
+ }
+ }
+
+ DOUT << "INTO: " << *PBI->getParent();
+
+ // This basic block is probably dead. We know it has at least
+ // one fewer predecessor.
+ return SimplifyCFG(BB) | true;
+ }
+ }
+ }
+ }
+ } else if (isa<UnreachableInst>(BB->getTerminator())) {
+ // If there are any instructions immediately before the unreachable that can
+ // be removed, do so.
+ Instruction *Unreachable = BB->getTerminator();
+ while (Unreachable != BB->begin()) {
+ BasicBlock::iterator BBI = Unreachable;
+ --BBI;
+ if (isa<CallInst>(BBI)) break;
+ // Delete this instruction
+ BB->getInstList().erase(BBI);
+ Changed = true;
+ }
+
+ // If the unreachable instruction is the first in the block, take a gander
+ // at all of the predecessors of this instruction, and simplify them.
+ if (&BB->front() == Unreachable) {
+ std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+ for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
+ TerminatorInst *TI = Preds[i]->getTerminator();
+
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+ if (BI->isUnconditional()) {
+ if (BI->getSuccessor(0) == BB) {
+ new UnreachableInst(TI);
+ TI->eraseFromParent();
+ Changed = true;
+ }
+ } else {
+ if (BI->getSuccessor(0) == BB) {
+ new BranchInst(BI->getSuccessor(1), BI);
+ BI->eraseFromParent();
+ } else if (BI->getSuccessor(1) == BB) {
+ new BranchInst(BI->getSuccessor(0), BI);
+ BI->eraseFromParent();
+ Changed = true;
+ }
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
+ if (SI->getSuccessor(i) == BB) {
+ BB->removePredecessor(SI->getParent());
+ SI->removeCase(i);
+ --i; --e;
+ Changed = true;
+ }
+ // If the default value is unreachable, figure out the most popular
+ // destination and make it the default.
+ if (SI->getSuccessor(0) == BB) {
+ std::map<BasicBlock*, unsigned> Popularity;
+ for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
+ Popularity[SI->getSuccessor(i)]++;
+
+ // Find the most popular block.
+ unsigned MaxPop = 0;
+ BasicBlock *MaxBlock = 0;
+ for (std::map<BasicBlock*, unsigned>::iterator
+ I = Popularity.begin(), E = Popularity.end(); I != E; ++I) {
+ if (I->second > MaxPop) {
+ MaxPop = I->second;
+ MaxBlock = I->first;
+ }
+ }
+ if (MaxBlock) {
+ // Make this the new default, allowing us to delete any explicit
+ // edges to it.
+ SI->setSuccessor(0, MaxBlock);
+ Changed = true;
+
+ // If MaxBlock has phinodes in it, remove MaxPop-1 entries from
+ // it.
+ if (isa<PHINode>(MaxBlock->begin()))
+ for (unsigned i = 0; i != MaxPop-1; ++i)
+ MaxBlock->removePredecessor(SI->getParent());
+
+ for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
+ if (SI->getSuccessor(i) == MaxBlock) {
+ SI->removeCase(i);
+ --i; --e;
+ }
+ }
+ }
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) {
+ if (II->getUnwindDest() == BB) {
+ // Convert the invoke to a call instruction. This would be a good
+ // place to note that the call does not throw though.
+ BranchInst *BI = new BranchInst(II->getNormalDest(), II);
+ II->removeFromParent(); // Take out of symbol table
+
+ // Insert the call now...
+ SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
+ CallInst *CI = new CallInst(II->getCalledValue(),
+ &Args[0], Args.size(),
+ II->getName(), BI);
+ CI->setCallingConv(II->getCallingConv());
+ // If the invoke produced a value, the Call does now instead.
+ II->replaceAllUsesWith(CI);
+ delete II;
+ Changed = true;
+ }
+ }
+ }
+
+ // If this block is now dead, remove it.
+ if (pred_begin(BB) == pred_end(BB)) {
+ // We know there are no successors, so just nuke the block.
+ M->getBasicBlockList().erase(BB);
+ return true;
+ }
+ }
+ }
+
+ // Merge basic blocks into their predecessor if there is only one distinct
+ // pred, and if there is only one distinct successor of the predecessor, and
+ // if there are no PHI nodes.
+ //
+ pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
+ BasicBlock *OnlyPred = *PI++;
+ for (; PI != PE; ++PI) // Search all predecessors, see if they are all same
+ if (*PI != OnlyPred) {
+ OnlyPred = 0; // There are multiple different predecessors...
+ break;
+ }
+
+ BasicBlock *OnlySucc = 0;
+ if (OnlyPred && OnlyPred != BB && // Don't break self loops
+ OnlyPred->getTerminator()->getOpcode() != Instruction::Invoke) {
+ // Check to see if there is only one distinct successor...
+ succ_iterator SI(succ_begin(OnlyPred)), SE(succ_end(OnlyPred));
+ OnlySucc = BB;
+ for (; SI != SE; ++SI)
+ if (*SI != OnlySucc) {
+ OnlySucc = 0; // There are multiple distinct successors!
+ break;
+ }
+ }
+
+ if (OnlySucc) {
+ DOUT << "Merging: " << *BB << "into: " << *OnlyPred;
+
+ // Resolve any PHI nodes at the start of the block. They are all
+ // guaranteed to have exactly one entry if they exist, unless there are
+ // multiple duplicate (but guaranteed to be equal) entries for the
+ // incoming edges. This occurs when there are multiple edges from
+ // OnlyPred to OnlySucc.
+ //
+ while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
+ PN->replaceAllUsesWith(PN->getIncomingValue(0));
+ BB->getInstList().pop_front(); // Delete the phi node.
+ }
+
+ // Delete the unconditional branch from the predecessor.
+ OnlyPred->getInstList().pop_back();
+
+ // Move all definitions in the successor to the predecessor.
+ OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
+
+ // Make all PHI nodes that referred to BB now refer to Pred as their
+ // source.
+ BB->replaceAllUsesWith(OnlyPred);
+
+ // Inherit predecessors name if it exists.
+ if (!OnlyPred->hasName())
+ OnlyPred->takeName(BB);
+
+ // Erase basic block from the function.
+ M->getBasicBlockList().erase(BB);
+
+ return true;
+ }
+
+ // Otherwise, if this block only has a single predecessor, and if that block
+ // is a conditional branch, see if we can hoist any code from this block up
+ // into our predecessor.
+ if (OnlyPred)
+ if (BranchInst *BI = dyn_cast<BranchInst>(OnlyPred->getTerminator()))
+ if (BI->isConditional()) {
+ // Get the other block.
+ BasicBlock *OtherBB = BI->getSuccessor(BI->getSuccessor(0) == BB);
+ PI = pred_begin(OtherBB);
+ ++PI;
+ if (PI == pred_end(OtherBB)) {
+ // We have a conditional branch to two blocks that are only reachable
+ // from the condbr. We know that the condbr dominates the two blocks,
+ // so see if there is any identical code in the "then" and "else"
+ // blocks. If so, we can hoist it up to the branching block.
+ Changed |= HoistThenElseCodeToIf(BI);
+ }
+ }
+
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ if (BranchInst *BI = dyn_cast<BranchInst>((*PI)->getTerminator()))
+ // Change br (X == 0 | X == 1), T, F into a switch instruction.
+ if (BI->isConditional() && isa<Instruction>(BI->getCondition())) {
+ Instruction *Cond = cast<Instruction>(BI->getCondition());
+ // If this is a bunch of seteq's or'd together, or if it's a bunch of
+ // 'setne's and'ed together, collect them.
+ Value *CompVal = 0;
+ std::vector<ConstantInt*> Values;
+ bool TrueWhenEqual = GatherValueComparisons(Cond, CompVal, Values);
+ if (CompVal && CompVal->getType()->isInteger()) {
+ // There might be duplicate constants in the list, which the switch
+ // instruction can't handle, remove them now.
+ std::sort(Values.begin(), Values.end(), ConstantIntOrdering());
+ Values.erase(std::unique(Values.begin(), Values.end()), Values.end());
+
+ // Figure out which block is which destination.
+ BasicBlock *DefaultBB = BI->getSuccessor(1);
+ BasicBlock *EdgeBB = BI->getSuccessor(0);
+ if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB);
+
+ // Create the new switch instruction now.
+ SwitchInst *New = new SwitchInst(CompVal, DefaultBB,Values.size(),BI);
+
+ // Add all of the 'cases' to the switch instruction.
+ for (unsigned i = 0, e = Values.size(); i != e; ++i)
+ New->addCase(Values[i], EdgeBB);
+
+ // We added edges from PI to the EdgeBB. As such, if there were any
+ // PHI nodes in EdgeBB, they need entries to be added corresponding to
+ // the number of edges added.
+ for (BasicBlock::iterator BBI = EdgeBB->begin();
+ isa<PHINode>(BBI); ++BBI) {
+ PHINode *PN = cast<PHINode>(BBI);
+ Value *InVal = PN->getIncomingValueForBlock(*PI);
+ for (unsigned i = 0, e = Values.size()-1; i != e; ++i)
+ PN->addIncoming(InVal, *PI);
+ }
+
+ // Erase the old branch instruction.
+ (*PI)->getInstList().erase(BI);
+
+ // Erase the potentially condition tree that was used to computed the
+ // branch condition.
+ ErasePossiblyDeadInstructionTree(Cond);
+ return true;
+ }
+ }
+
+ // If there is a trivial two-entry PHI node in this basic block, and we can
+ // eliminate it, do so now.
+ if (PHINode *PN = dyn_cast<PHINode>(BB->begin()))
+ if (PN->getNumIncomingValues() == 2)
+ Changed |= FoldTwoEntryPHINode(PN);
+
+ return Changed;
+}
diff --git a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
new file mode 100644
index 0000000..b545ad3
--- /dev/null
+++ b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -0,0 +1,138 @@
+//===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is used to ensure that functions have at most one return
+// instruction in them. Additionally, it keeps track of which node is the new
+// exit node of the CFG. If there are no exit nodes in the CFG, the getExitNode
+// method will return a null pointer.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+using namespace llvm;
+
+char UnifyFunctionExitNodes::ID = 0;
+static RegisterPass<UnifyFunctionExitNodes>
+X("mergereturn", "Unify function exit nodes");
+
+int UnifyFunctionExitNodes::stub;
+
+Pass *llvm::createUnifyFunctionExitNodesPass() {
+ return new UnifyFunctionExitNodes();
+}
+
+void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
+ // We preserve the non-critical-edgeness property
+ AU.addPreservedID(BreakCriticalEdgesID);
+ // This is a cluster of orthogonal Transforms
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerSwitchID);
+}
+
+// UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
+// BasicBlock, and converting all returns to unconditional branches to this
+// new basic block. The singular exit node is returned.
+//
+// If there are no return stmts in the Function, a null pointer is returned.
+//
+bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
+ // Loop over all of the blocks in a function, tracking all of the blocks that
+ // return.
+ //
+ std::vector<BasicBlock*> ReturningBlocks;
+ std::vector<BasicBlock*> UnwindingBlocks;
+ std::vector<BasicBlock*> UnreachableBlocks;
+ for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ if (isa<ReturnInst>(I->getTerminator()))
+ ReturningBlocks.push_back(I);
+ else if (isa<UnwindInst>(I->getTerminator()))
+ UnwindingBlocks.push_back(I);
+ else if (isa<UnreachableInst>(I->getTerminator()))
+ UnreachableBlocks.push_back(I);
+
+ // Handle unwinding blocks first.
+ if (UnwindingBlocks.empty()) {
+ UnwindBlock = 0;
+ } else if (UnwindingBlocks.size() == 1) {
+ UnwindBlock = UnwindingBlocks.front();
+ } else {
+ UnwindBlock = new BasicBlock("UnifiedUnwindBlock", &F);
+ new UnwindInst(UnwindBlock);
+
+ for (std::vector<BasicBlock*>::iterator I = UnwindingBlocks.begin(),
+ E = UnwindingBlocks.end(); I != E; ++I) {
+ BasicBlock *BB = *I;
+ BB->getInstList().pop_back(); // Remove the unwind insn
+ new BranchInst(UnwindBlock, BB);
+ }
+ }
+
+ // Then unreachable blocks.
+ if (UnreachableBlocks.empty()) {
+ UnreachableBlock = 0;
+ } else if (UnreachableBlocks.size() == 1) {
+ UnreachableBlock = UnreachableBlocks.front();
+ } else {
+ UnreachableBlock = new BasicBlock("UnifiedUnreachableBlock", &F);
+ new UnreachableInst(UnreachableBlock);
+
+ for (std::vector<BasicBlock*>::iterator I = UnreachableBlocks.begin(),
+ E = UnreachableBlocks.end(); I != E; ++I) {
+ BasicBlock *BB = *I;
+ BB->getInstList().pop_back(); // Remove the unreachable inst.
+ new BranchInst(UnreachableBlock, BB);
+ }
+ }
+
+ // Now handle return blocks.
+ if (ReturningBlocks.empty()) {
+ ReturnBlock = 0;
+ return false; // No blocks return
+ } else if (ReturningBlocks.size() == 1) {
+ ReturnBlock = ReturningBlocks.front(); // Already has a single return block
+ return false;
+ }
+
+ // Otherwise, we need to insert a new basic block into the function, add a PHI
+ // node (if the function returns a value), and convert all of the return
+ // instructions into unconditional branches.
+ //
+ BasicBlock *NewRetBlock = new BasicBlock("UnifiedReturnBlock", &F);
+
+ PHINode *PN = 0;
+ if (F.getReturnType() != Type::VoidTy) {
+ // If the function doesn't return void... add a PHI node to the block...
+ PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+ NewRetBlock->getInstList().push_back(PN);
+ }
+ new ReturnInst(PN, NewRetBlock);
+
+ // Loop over all of the blocks, replacing the return instruction with an
+ // unconditional branch.
+ //
+ for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
+ E = ReturningBlocks.end(); I != E; ++I) {
+ BasicBlock *BB = *I;
+
+ // Add an incoming element to the PHI node for every return instruction that
+ // is merging into this new block...
+ if (PN) PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
+
+ BB->getInstList().pop_back(); // Remove the return insn
+ new BranchInst(NewRetBlock, BB);
+ }
+ ReturnBlock = NewRetBlock;
+ return true;
+}
diff --git a/lib/Transforms/Utils/ValueMapper.cpp b/lib/Transforms/Utils/ValueMapper.cpp
new file mode 100644
index 0000000..0b8c5c2
--- /dev/null
+++ b/lib/Transforms/Utils/ValueMapper.cpp
@@ -0,0 +1,118 @@
+//===- ValueMapper.cpp - Interface shared by lib/Transforms/Utils ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MapValue function, which is shared by various parts of
+// the lib/Transforms/Utils library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ValueMapper.h"
+#include "llvm/Constants.h"
+#include "llvm/GlobalValue.h"
+#include "llvm/Instruction.h"
+using namespace llvm;
+
+Value *llvm::MapValue(const Value *V, ValueMapTy &VM) {
+ Value *&VMSlot = VM[V];
+ if (VMSlot) return VMSlot; // Does it exist in the map yet?
+
+ // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
+ // DenseMap. This includes any recursive calls to MapValue.
+
+ // Global values do not need to be seeded into the ValueMap if they are using
+ // the identity mapping.
+ if (isa<GlobalValue>(V) || isa<InlineAsm>(V))
+ return VMSlot = const_cast<Value*>(V);
+
+ if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V))) {
+ if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
+ isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
+ isa<UndefValue>(C))
+ return VMSlot = C; // Primitive constants map directly
+ else if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
+ for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
+ Value *MV = MapValue(CA->getOperand(i), VM);
+ if (MV != CA->getOperand(i)) {
+ // This array must contain a reference to a global, make a new array
+ // and return it.
+ //
+ std::vector<Constant*> Values;
+ Values.reserve(CA->getNumOperands());
+ for (unsigned j = 0; j != i; ++j)
+ Values.push_back(CA->getOperand(j));
+ Values.push_back(cast<Constant>(MV));
+ for (++i; i != e; ++i)
+ Values.push_back(cast<Constant>(MapValue(CA->getOperand(i), VM)));
+ return VM[V] = ConstantArray::get(CA->getType(), Values);
+ }
+ }
+ return VM[V] = C;
+
+ } else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
+ for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
+ Value *MV = MapValue(CS->getOperand(i), VM);
+ if (MV != CS->getOperand(i)) {
+ // This struct must contain a reference to a global, make a new struct
+ // and return it.
+ //
+ std::vector<Constant*> Values;
+ Values.reserve(CS->getNumOperands());
+ for (unsigned j = 0; j != i; ++j)
+ Values.push_back(CS->getOperand(j));
+ Values.push_back(cast<Constant>(MV));
+ for (++i; i != e; ++i)
+ Values.push_back(cast<Constant>(MapValue(CS->getOperand(i), VM)));
+ return VM[V] = ConstantStruct::get(CS->getType(), Values);
+ }
+ }
+ return VM[V] = C;
+
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
+ std::vector<Constant*> Ops;
+ for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
+ Ops.push_back(cast<Constant>(MapValue(CE->getOperand(i), VM)));
+ return VM[V] = CE->getWithOperands(Ops);
+ } else if (ConstantVector *CP = dyn_cast<ConstantVector>(C)) {
+ for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
+ Value *MV = MapValue(CP->getOperand(i), VM);
+ if (MV != CP->getOperand(i)) {
+ // This vector value must contain a reference to a global, make a new
+ // vector constant and return it.
+ //
+ std::vector<Constant*> Values;
+ Values.reserve(CP->getNumOperands());
+ for (unsigned j = 0; j != i; ++j)
+ Values.push_back(CP->getOperand(j));
+ Values.push_back(cast<Constant>(MV));
+ for (++i; i != e; ++i)
+ Values.push_back(cast<Constant>(MapValue(CP->getOperand(i), VM)));
+ return VM[V] = ConstantVector::get(Values);
+ }
+ }
+ return VM[V] = C;
+
+ } else {
+ assert(0 && "Unknown type of constant!");
+ }
+ }
+
+ return 0;
+}
+
+/// RemapInstruction - Convert the instruction operands from referencing the
+/// current values into those specified by ValueMap.
+///
+void llvm::RemapInstruction(Instruction *I, ValueMapTy &ValueMap) {
+ for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
+ const Value *Op = I->getOperand(op);
+ Value *V = MapValue(Op, ValueMap);
+ assert(V && "Referenced value not in value map!");
+ I->setOperand(op, V);
+ }
+}
diff --git a/lib/Transforms/Utils/ValueMapper.h b/lib/Transforms/Utils/ValueMapper.h
new file mode 100644
index 0000000..51319db
--- /dev/null
+++ b/lib/Transforms/Utils/ValueMapper.h
@@ -0,0 +1,29 @@
+//===- ValueMapper.h - Interface shared by lib/Transforms/Utils -*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MapValue interface which is used by various parts of
+// the Transforms/Utils library to implement cloning and linking facilities.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef VALUEMAPPER_H
+#define VALUEMAPPER_H
+
+#include "llvm/ADT/DenseMap.h"
+
+namespace llvm {
+ class Value;
+ class Instruction;
+ typedef DenseMap<const Value *, Value *> ValueMapTy;
+
+ Value *MapValue(const Value *V, ValueMapTy &VM);
+ void RemapInstruction(Instruction *I, ValueMapTy &VM);
+} // End llvm namespace
+
+#endif