-//===- llvm/Transforms/LowerAllocations.h - Remove Malloc & Free Insts ------=//
+//===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===//
//
-// This file implements a pass that lowers malloc and free instructions to
-// calls to %malloc & %free functions. This transformation is a target
-// dependant tranformation because we depend on the size of data types and
-// alignment constraints.
+// 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/LowerAllocations.h"
-#include "llvm/Target/TargetData.h"
+#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/iMemory.h"
-#include "llvm/iOther.h"
-#include "llvm/SymbolTable.h"
-#include "llvm/ConstantVals.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
+ 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(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");
+}
-// doPassInitialization - For the lower allocations pass, this ensures that a
+// 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::doPassInitialization(Module *M) {
- bool Changed = false;
- const MethodType *MallocType =
- MethodType::get(PointerType::get(Type::SByteTy),
- vector<const Type*>(1, Type::UIntTy), false);
-
- SymbolTable *SymTab = M->getSymbolTableSure();
-
- // Check for a definition of malloc
- if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) {
- MallocMeth = cast<Method>(V); // Yup, got it
- } else { // Nope, add one
- M->getMethodList().push_back(MallocMeth = new Method(MallocType, false,
- "malloc"));
- Changed = true;
- }
-
- const MethodType *FreeType =
- MethodType::get(Type::VoidTy,
- vector<const Type*>(1, PointerType::get(Type::SByteTy)),
- false);
-
- // Check for a definition of free
- if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) {
- FreeMeth = cast<Method>(V); // Yup, got it
- } else { // Nope, add one
- M->getMethodList().push_back(FreeMeth = new Method(FreeType, false,"free"));
- Changed = true;
- }
-
- return Changed; // Always successful
+bool LowerAllocations::doInitialization(Module &M) {
+ 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;
}
-// doPerMethodWork - This method does the actual work of converting
+// runOnBasicBlock - This method does the actual work of converting
// instructions over, assuming that the pass has already been initialized.
//
-bool LowerAllocations::doPerMethodWork(Method *M) {
+bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
bool Changed = false;
- assert(MallocMeth && FreeMeth && M && "Pass not initialized!");
+ 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 (Method::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) {
- BasicBlock *BB = *BBI;
- for (unsigned i = 0; i < BB->size(); ++i) {
- BasicBlock::InstListType &BBIL = BB->getInstList();
- if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) {
- BBIL.remove(BBIL.begin()+i); // remove the malloc instr...
-
- const Type *AllocTy =cast<PointerType>(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) {
+ 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.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 (MI->getNumOperands()) {
- // Multiply it by the array size if neccesary...
- MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
- MallocArg);
- BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg));
+ } 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(MallocMeth,
- vector<Value*>(1, MallocArg));
- BBIL.insert(BBIL.begin()+i, MCall);
-
- // Create a cast instruction to convert to the right type...
- CastInst *MCast = new CastInst(MCall, MI->getType());
- BBIL.insert(BBIL.begin()+i+1, MCast);
-
- // Replace all uses of the old malloc inst with the cast inst
- MI->replaceAllUsesWith(MCast);
- delete MI; // Delete the malloc inst
- Changed = true;
- } else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) {
- BBIL.remove(BB->getInstList().begin()+i);
-
- // Cast the argument to free into a ubyte*...
- CastInst *MCast = new CastInst(FI->getOperand(0),
- PointerType::get(Type::UByteTy));
- BBIL.insert(BBIL.begin()+i, MCast);
-
- // Insert a call to the free function...
- CallInst *FCall = new CallInst(FreeMeth,
- vector<Value*>(1, MCast));
- BBIL.insert(BBIL.begin()+i+1, FCall);
-
- // Delete the old free instruction
- delete FI;
- Changed = true;
}
+
+ // 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::getUnqual(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;
}
}
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