| //===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file 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/LLVMContext.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 *FreeFunc; // Functions in the module we are processing |
| // Initialized by doInitialization |
| bool LowerMallocArgToInteger; |
| public: |
| static char ID; // Pass ID, replacement for typeid |
| explicit LowerAllocations(bool LowerToInt = false) |
| : BasicBlockPass(&ID), 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(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 doInitialization(*F.getParent()); |
| } |
| |
| /// 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; |
| static RegisterPass<LowerAllocations> |
| X("lowerallocs", "Lower allocations from instructions to calls"); |
| |
| // Publically exposed interface to pass... |
| const PassInfo *const llvm::LowerAllocationsID = &X; |
| // 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 = Type::getInt8PtrTy(M.getContext()); |
| FreeFunc = M.getOrInsertFunction("free" , Type::getVoidTy(M.getContext()), |
| 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(FreeFunc && "Pass not initialized!"); |
| |
| BasicBlock::InstListType &BBIL = BB.getInstList(); |
| |
| const TargetData &TD = getAnalysis<TargetData>(); |
| const Type *IntPtrTy = TD.getIntPtrType(BB.getContext()); |
| |
| // 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)) { |
| Value *ArraySize = MI->getOperand(0); |
| if (ArraySize->getType() != IntPtrTy) |
| ArraySize = CastInst::CreateIntegerCast(ArraySize, IntPtrTy, |
| false /*ZExt*/, "", I); |
| Value *MCast = CallInst::CreateMalloc(I, IntPtrTy, |
| MI->getAllocatedType(), ArraySize); |
| |
| // 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), |
| Type::getInt8PtrTy(BB.getContext()), "", I); |
| |
| // Insert a call to the free function... |
| CallInst::Create(FreeFunc, PtrCast, "", I)->setTailCall(); |
| |
| // Delete the old free instruction |
| I = --BBIL.erase(I); |
| Changed = true; |
| ++NumLowered; |
| } |
| } |
| |
| return Changed; |
| } |
| |