| //===- CodeExtractor.cpp - Pull code region into a new function -----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file 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/LLVMContext.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/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/ADT/SetVector.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 extractor. 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 CodeExtractor { |
| typedef SetVector<Value*> Values; |
| SetVector<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->getFirstNonPHI(); |
| 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.remove(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 = PHINode::Create(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 (SetVector<BasicBlock*>::iterator I = BlocksToExtract.begin(), |
| E = BlocksToExtract.end(); I != E; ++I) |
| if (ReturnInst *RI = dyn_cast<ReturnInst>((*I)->getTerminator())) { |
| BasicBlock *New = (*I)->splitBasicBlock(RI, (*I)->getName()+".ret"); |
| if (DT) { |
| // Old dominates New. New node domiantes all other nodes dominated |
| //by Old. |
| DomTreeNode *OldNode = DT->getNode(*I); |
| SmallVector<DomTreeNode*, 8> Children; |
| for (DomTreeNode::iterator DI = OldNode->begin(), DE = OldNode->end(); |
| DI != DE; ++DI) |
| Children.push_back(*DI); |
| |
| DomTreeNode *NewNode = DT->addNewBlock(New, *I); |
| |
| for (SmallVector<DomTreeNode*, 8>::iterator I = Children.begin(), |
| E = Children.end(); I != E; ++I) |
| DT->changeImmediateDominator(*I, NewNode); |
| } |
| } |
| } |
| |
| // findInputsOutputs - Find inputs to, outputs from the code region. |
| // |
| void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs) { |
| std::set<BasicBlock*> ExitBlocks; |
| for (SetVector<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.insert(*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.insert(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(); |
| } |
| |
| /// 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) { |
| DEBUG(dbgs() << "inputs: " << inputs.size() << "\n"); |
| DEBUG(dbgs() << "outputs: " << outputs.size() << "\n"); |
| |
| // This function returns unsigned, outputs will go back by reference. |
| switch (NumExitBlocks) { |
| case 0: |
| case 1: RetTy = Type::getVoidTy(header->getContext()); break; |
| case 2: RetTy = Type::getInt1Ty(header->getContext()); break; |
| default: RetTy = Type::getInt16Ty(header->getContext()); 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; |
| DEBUG(dbgs() << "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) { |
| DEBUG(dbgs() << "instr used in func: " << **I << "\n"); |
| if (AggregateArgs) |
| paramTy.push_back((*I)->getType()); |
| else |
| paramTy.push_back(PointerType::getUnqual((*I)->getType())); |
| } |
| |
| DEBUG(dbgs() << "Function type: " << *RetTy << " f("); |
| for (std::vector<const Type*>::iterator i = paramTy.begin(), |
| e = paramTy.end(); i != e; ++i) |
| DEBUG(dbgs() << **i << ", "); |
| DEBUG(dbgs() << ")\n"); |
| |
| if (AggregateArgs && (inputs.size() + outputs.size() > 0)) { |
| PointerType *StructPtr = |
| PointerType::getUnqual(StructType::get(M->getContext(), paramTy)); |
| paramTy.clear(); |
| paramTy.push_back(StructPtr); |
| } |
| const FunctionType *funcType = |
| FunctionType::get(RetTy, paramTy, false); |
| |
| // Create the new function |
| Function *newFunction = Function::Create(funcType, |
| GlobalValue::InternalLinkage, |
| oldFunction->getName() + "_" + |
| header->getName(), M); |
| // If the old function is no-throw, so is the new one. |
| if (oldFunction->doesNotThrow()) |
| newFunction->setDoesNotThrow(true); |
| |
| 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 *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::getInt32Ty(header->getContext())); |
| Idx[1] = ConstantInt::get(Type::getInt32Ty(header->getContext()), i); |
| TerminatorInst *TI = newFunction->begin()->getTerminator(); |
| GetElementPtrInst *GEP = |
| GetElementPtrInst::Create(AI, Idx, Idx+2, |
| "gep_" + inputs[i]->getName(), TI); |
| RewriteVal = new LoadInst(GEP, "loadgep_" + inputs[i]->getName(), 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; |
| } |
| |
| /// FindPhiPredForUseInBlock - Given a value and a basic block, find a PHI |
| /// that uses the value within the basic block, and return the predecessor |
| /// block associated with that use, or return 0 if none is found. |
| static BasicBlock* FindPhiPredForUseInBlock(Value* Used, BasicBlock* BB) { |
| for (Value::use_iterator UI = Used->use_begin(), |
| UE = Used->use_end(); UI != UE; ++UI) { |
| PHINode *P = dyn_cast<PHINode>(*UI); |
| if (P && P->getParent() == BB) |
| return P->getIncomingBlock(UI); |
| } |
| |
| return 0; |
| } |
| |
| /// 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, Reloads; |
| |
| LLVMContext &Context = newFunction->getContext(); |
| |
| // 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(newFunction->getContext(), 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 *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context)); |
| Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), i); |
| GetElementPtrInst *GEP = |
| GetElementPtrInst::Create(Struct, Idx, Idx + 2, |
| "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 = CallInst::Create(newFunction, params.begin(), params.end(), |
| 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 *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context)); |
| Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), FirstOut + i); |
| GetElementPtrInst *GEP |
| = GetElementPtrInst::Create(Struct, Idx, Idx + 2, |
| "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"); |
| Reloads.push_back(load); |
| 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 = |
| SwitchInst::Create(Constant::getNullValue(Type::getInt16Ty(Context)), |
| 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 (SetVector<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 = BasicBlock::Create(Context, |
| 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::getInt1Ty(Context), !SuccNum); |
| break; |
| default: |
| brVal = ConstantInt::get(Type::getInt16Ty(Context), SuccNum); |
| break; |
| } |
| |
| ReturnInst *NTRet = ReturnInst::Create(Context, brVal, NewTarget); |
| |
| // Update the switch instruction. |
| TheSwitch->addCase(ConstantInt::get(Type::getInt16Ty(Context), |
| 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 the output value is used by a phi in the target block, |
| // then we need to test for dominance of the phi's predecessor |
| // instead. Unfortunately, this a little complicated since we |
| // have already rewritten uses of the value to uses of the reload. |
| BasicBlock* pred = FindPhiPredForUseInBlock(Reloads[out], |
| OldTarget); |
| if (pred && DT && DT->dominates(DefBlock, pred)) |
| DominatesDef = true; |
| } |
| |
| if (DominatesDef) { |
| if (AggregateArgs) { |
| Value *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context)); |
| Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), |
| FirstOut+out); |
| GetElementPtrInst *GEP = |
| GetElementPtrInst::Create(OAI, Idx, Idx + 2, |
| "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->isVoidTy()) { |
| ReturnInst::Create(Context, 0, TheSwitch); // Return void |
| } else if (OldFnRetTy == TheSwitch->getCondition()->getType()) { |
| // return what we have |
| ReturnInst::Create(Context, TheSwitch->getCondition(), TheSwitch); |
| } else { |
| // Otherwise we must have code extracted an unwind or something, just |
| // return whatever we want. |
| ReturnInst::Create(Context, |
| Constant::getNullValue(OldFnRetTy), TheSwitch); |
| } |
| |
| TheSwitch->eraseFromParent(); |
| break; |
| case 1: |
| // Only a single destination, change the switch into an unconditional |
| // branch. |
| BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch); |
| TheSwitch->eraseFromParent(); |
| break; |
| case 2: |
| BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch->getSuccessor(2), |
| call, TheSwitch); |
| TheSwitch->eraseFromParent(); |
| 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 (SetVector<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 = BasicBlock::Create(header->getContext(), |
| "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 = BasicBlock::Create(header->getContext(), |
| "newFuncRoot"); |
| newFuncRoot->getInstList().push_back(BranchInst::Create(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)) |
| llvm_report_error("verifyFunction failed!")); |
| 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); |
| } |