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/IPO/PruneEH.cpp b/lib/Transforms/IPO/PruneEH.cpp
new file mode 100644
index 0000000..a783272
--- /dev/null
+++ b/lib/Transforms/IPO/PruneEH.cpp
@@ -0,0 +1,233 @@
+//===- PruneEH.cpp - Pass which deletes unused exception handlers ---------===//
+//
+// 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 a simple interprocedural pass which walks the
+// call-graph, turning invoke instructions into calls, iff the callee cannot
+// throw an exception. It implements this as a bottom-up traversal of the
+// call-graph.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "prune-eh"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/CallGraphSCCPass.h"
+#include "llvm/Constants.h"
+#include "llvm/Function.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Instructions.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include <set>
+#include <algorithm>
+using namespace llvm;
+
+STATISTIC(NumRemoved, "Number of invokes removed");
+STATISTIC(NumUnreach, "Number of noreturn calls optimized");
+
+namespace {
+ struct VISIBILITY_HIDDEN PruneEH : public CallGraphSCCPass {
+ static char ID; // Pass identification, replacement for typeid
+ PruneEH() : CallGraphSCCPass((intptr_t)&ID) {}
+
+ /// DoesNotUnwind - This set contains all of the functions which we have
+ /// determined cannot unwind.
+ std::set<CallGraphNode*> DoesNotUnwind;
+
+ /// DoesNotReturn - This set contains all of the functions which we have
+ /// determined cannot return normally (but might unwind).
+ std::set<CallGraphNode*> DoesNotReturn;
+
+ // runOnSCC - Analyze the SCC, performing the transformation if possible.
+ bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
+
+ bool SimplifyFunction(Function *F);
+ void DeleteBasicBlock(BasicBlock *BB);
+ };
+
+ char PruneEH::ID = 0;
+ RegisterPass<PruneEH> X("prune-eh", "Remove unused exception handling info");
+}
+
+Pass *llvm::createPruneEHPass() { return new PruneEH(); }
+
+
+bool PruneEH::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
+ CallGraph &CG = getAnalysis<CallGraph>();
+ bool MadeChange = false;
+
+ // First pass, scan all of the functions in the SCC, simplifying them
+ // according to what we know.
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+ if (Function *F = SCC[i]->getFunction())
+ MadeChange |= SimplifyFunction(F);
+
+ // Next, check to see if any callees might throw or if there are any external
+ // functions in this SCC: if so, we cannot prune any functions in this SCC.
+ // If this SCC includes the unwind instruction, we KNOW it throws, so
+ // obviously the SCC might throw.
+ //
+ bool SCCMightUnwind = false, SCCMightReturn = false;
+ for (unsigned i = 0, e = SCC.size();
+ (!SCCMightUnwind || !SCCMightReturn) && i != e; ++i) {
+ Function *F = SCC[i]->getFunction();
+ if (F == 0 || (F->isDeclaration() && !F->getIntrinsicID())) {
+ SCCMightUnwind = true;
+ SCCMightReturn = true;
+ } else {
+ if (F->isDeclaration())
+ SCCMightReturn = true;
+
+ // Check to see if this function performs an unwind or calls an
+ // unwinding function.
+ for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+ if (isa<UnwindInst>(BB->getTerminator())) { // Uses unwind!
+ SCCMightUnwind = true;
+ } else if (isa<ReturnInst>(BB->getTerminator())) {
+ SCCMightReturn = true;
+ }
+
+ // Invoke instructions don't allow unwinding to continue, so we are
+ // only interested in call instructions.
+ if (!SCCMightUnwind)
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+ if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ if (Function *Callee = CI->getCalledFunction()) {
+ CallGraphNode *CalleeNode = CG[Callee];
+ // If the callee is outside our current SCC, or if it is not
+ // known to throw, then we might throw also.
+ if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()&&
+ !DoesNotUnwind.count(CalleeNode)) {
+ SCCMightUnwind = true;
+ break;
+ }
+ } else {
+ // Indirect call, it might throw.
+ SCCMightUnwind = true;
+ break;
+ }
+ }
+ if (SCCMightUnwind && SCCMightReturn) break;
+ }
+ }
+ }
+
+ // If the SCC doesn't unwind or doesn't throw, note this fact.
+ if (!SCCMightUnwind)
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+ DoesNotUnwind.insert(SCC[i]);
+ if (!SCCMightReturn)
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+ DoesNotReturn.insert(SCC[i]);
+
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+ // Convert any invoke instructions to non-throwing functions in this node
+ // into call instructions with a branch. This makes the exception blocks
+ // dead.
+ if (Function *F = SCC[i]->getFunction())
+ MadeChange |= SimplifyFunction(F);
+ }
+
+ return MadeChange;
+}
+
+
+// SimplifyFunction - Given information about callees, simplify the specified
+// function if we have invokes to non-unwinding functions or code after calls to
+// no-return functions.
+bool PruneEH::SimplifyFunction(Function *F) {
+ CallGraph &CG = getAnalysis<CallGraph>();
+ bool MadeChange = false;
+ for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+ if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
+ if (Function *F = II->getCalledFunction())
+ if (DoesNotUnwind.count(CG[F])) {
+ SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
+ // Insert a call instruction before the invoke.
+ CallInst *Call = new CallInst(II->getCalledValue(),
+ &Args[0], Args.size(), "", II);
+ Call->takeName(II);
+ Call->setCallingConv(II->getCallingConv());
+
+ // Anything that used the value produced by the invoke instruction
+ // now uses the value produced by the call instruction.
+ II->replaceAllUsesWith(Call);
+ BasicBlock *UnwindBlock = II->getUnwindDest();
+ UnwindBlock->removePredecessor(II->getParent());
+
+ // Insert a branch to the normal destination right before the
+ // invoke.
+ new BranchInst(II->getNormalDest(), II);
+
+ // Finally, delete the invoke instruction!
+ BB->getInstList().pop_back();
+
+ // If the unwind block is now dead, nuke it.
+ if (pred_begin(UnwindBlock) == pred_end(UnwindBlock))
+ DeleteBasicBlock(UnwindBlock); // Delete the new BB.
+
+ ++NumRemoved;
+ MadeChange = true;
+ }
+
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
+ if (CallInst *CI = dyn_cast<CallInst>(I++))
+ if (Function *Callee = CI->getCalledFunction())
+ if (DoesNotReturn.count(CG[Callee]) && !isa<UnreachableInst>(I)) {
+ // This call calls a function that cannot return. Insert an
+ // unreachable instruction after it and simplify the code. Do this
+ // by splitting the BB, adding the unreachable, then deleting the
+ // new BB.
+ BasicBlock *New = BB->splitBasicBlock(I);
+
+ // Remove the uncond branch and add an unreachable.
+ BB->getInstList().pop_back();
+ new UnreachableInst(BB);
+
+ DeleteBasicBlock(New); // Delete the new BB.
+ MadeChange = true;
+ ++NumUnreach;
+ break;
+ }
+
+ }
+ return MadeChange;
+}
+
+/// DeleteBasicBlock - remove the specified basic block from the program,
+/// updating the callgraph to reflect any now-obsolete edges due to calls that
+/// exist in the BB.
+void PruneEH::DeleteBasicBlock(BasicBlock *BB) {
+ assert(pred_begin(BB) == pred_end(BB) && "BB is not dead!");
+ CallGraph &CG = getAnalysis<CallGraph>();
+
+ CallGraphNode *CGN = CG[BB->getParent()];
+ for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
+ --I;
+ if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ if (Function *Callee = CI->getCalledFunction())
+ CGN->removeCallEdgeTo(CG[Callee]);
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
+ if (Function *Callee = II->getCalledFunction())
+ CGN->removeCallEdgeTo(CG[Callee]);
+ }
+ if (!I->use_empty())
+ I->replaceAllUsesWith(UndefValue::get(I->getType()));
+ }
+
+ // Get the list of successors of this block.
+ std::vector<BasicBlock*> Succs(succ_begin(BB), succ_end(BB));
+
+ for (unsigned i = 0, e = Succs.size(); i != e; ++i)
+ Succs[i]->removePredecessor(BB);
+
+ BB->eraseFromParent();
+}