//===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===//
//
-// The LowerAllocations transformation is a target dependant tranformation
+// 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.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/ChangeAllocations.h"
+#define DEBUG_TYPE "lowerallocs"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
#include "llvm/Module.h"
-#include "llvm/Function.h"
-#include "llvm/BasicBlock.h"
#include "llvm/DerivedTypes.h"
-#include "llvm/iMemory.h"
-#include "llvm/iOther.h"
+#include "llvm/Instructions.h"
#include "llvm/Constants.h"
#include "llvm/Pass.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Target/TargetData.h"
-#include "Support/StatisticReporter.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
-static Statistic<> NumLowered("lowerallocs\t- Number of allocations lowered");
-using std::vector;
+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
+ explicit 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(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ }
-// LowerAllocations - Turn malloc and free instructions into %malloc and %free
-// calls.
-//
-class LowerAllocations : public BasicBlockPass {
- Function *MallocFunc; // Functions in the module we are processing
- Function *FreeFunc; // Initialized by doInitialization
-
- const TargetData &DataLayout;
-public:
- inline LowerAllocations(const TargetData &TD) : DataLayout(TD) {
- MallocFunc = FreeFunc = 0;
- }
-
- const char *getPassName() const { return "Lower Allocations"; }
+ /// 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);
- // 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);
-};
+ /// 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 *createLowerAllocationsPass(const TargetData &TD) {
- return new LowerAllocations(TD);
+Pass *llvm::createLowerAllocationsPass(bool LowerMallocArgToInteger) {
+ return new LowerAllocations(LowerMallocArgToInteger);
}
// This function is always successful.
//
bool LowerAllocations::doInitialization(Module &M) {
- const FunctionType *MallocType =
- FunctionType::get(PointerType::get(Type::SByteTy),
- vector<const Type*>(1, Type::UIntTy), false);
- const FunctionType *FreeType =
- FunctionType::get(Type::VoidTy,
- vector<const Type*>(1, PointerType::get(Type::SByteTy)),
- false);
-
- MallocFunc = M.getOrInsertFunction("malloc", MallocType);
- FreeFunc = M.getOrInsertFunction("free" , FreeType);
-
+ const Type *BPTy = PointerType::getUnqual(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;
}
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)) {
- BBIL.remove(I); // remove the malloc instr...
-
+ if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
const Type *AllocTy = MI->getType()->getElementType();
-
- // Get the number of bytes to be allocated for one element of the
- // requested type...
- unsigned Size = DataLayout.getTypeSize(AllocTy);
-
- // malloc(type) becomes sbyte *malloc(constint)
- Value *MallocArg = ConstantUInt::get(Type::UIntTy, Size);
- if (MI->getNumOperands() && Size == 1) {
- MallocArg = MI->getOperand(0); // Operand * 1 = Operand
- } else if (MI->getNumOperands()) {
- // Multiply it by the array size if neccesary...
- MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
- MallocArg);
- I = ++BBIL.insert(I, cast<Instruction>(MallocArg));
+
+ // malloc(type) becomes sbyte *malloc(size)
+ Value *MallocArg;
+ if (LowerMallocArgToInteger)
+ MallocArg = ConstantInt::get(Type::Int64Ty, TD.getABITypeSize(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,
- vector<Value*>(1, MallocArg));
- I = BBIL.insert(I, MCall);
-
+
+ // Create the call to Malloc.
+ CallInst *MCall = new CallInst(MallocFunc, MallocArg, "", I);
+ MCall->setTailCall();
+
// Create a cast instruction to convert to the right type...
- CastInst *MCast = new CastInst(MCall, MI->getType());
- I = BBIL.insert(++I, MCast);
-
+ 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);
- delete MI; // Delete the malloc inst
+ I = --BBIL.erase(I); // remove and delete the malloc instr...
Changed = true;
++NumLowered;
- } else if (FreeInst *FI = dyn_cast<FreeInst>(&*I)) {
- BBIL.remove(I);
-
- // Cast the argument to free into a ubyte*...
- CastInst *MCast = new CastInst(FI->getOperand(0),
- PointerType::get(Type::UByteTy));
- I = ++BBIL.insert(I, MCast);
-
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(I)) {
+ Value *PtrCast =
+ new BitCastInst(FI->getOperand(0),
+ PointerType::getUnqual(Type::Int8Ty), "", I);
+
// Insert a call to the free function...
- CallInst *FCall = new CallInst(FreeFunc, vector<Value*>(1, MCast));
- I = BBIL.insert(I, FCall);
-
+ (new CallInst(FreeFunc, PtrCast, "", I))->setTailCall();
+
// Delete the old free instruction
- delete FI;
+ I = --BBIL.erase(I);
Changed = true;
++NumLowered;
}
return Changed;
}
+