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Implement transmogriphication of allocation instructions

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9654 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-11-02 05:57:39 +00:00
parent fc424c39de
commit bc61e661bd
1 changed files with 33 additions and 2 deletions
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35
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -34,14 +34,15 @@
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Constants.h"
#include "llvm/ConstantHandling.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Support/CallSite.h"
@ -57,6 +58,7 @@ namespace {
public InstVisitor<InstCombiner, Instruction*> {
// Worklist of all of the instructions that need to be simplified.
std::vector<Instruction*> WorkList;
TargetData *TD;
void AddUsesToWorkList(Instruction &I) {
// The instruction was simplified, add all users of the instruction to
@ -73,6 +75,7 @@ namespace {
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetData>();
AU.setPreservesCFG();
}
@ -1536,6 +1539,33 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
}
}
// If we are casting a malloc or alloca to a pointer to a type of the same
// size, rewrite the allocation instruction to allocate the "right" type.
//
if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
if (AI->hasOneUse())
if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
// Get the type really allocated and the type casted to...
const Type *AllocElTy = AI->getAllocatedType();
unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
const Type *CastElTy = PTy->getElementType();
unsigned CastElTySize = TD->getTypeSize(CastElTy);
// If the allocation is for an even multiple of the cast type size
if (AllocElTySize % CastElTySize == 0) {
Value *Amt = ConstantUInt::get(Type::UIntTy,
AllocElTySize/CastElTySize);
std::string Name = AI->getName(); AI->setName("");
AllocationInst *New;
if (isa<MallocInst>(AI))
New = new MallocInst(CastElTy, Amt, Name);
else
New = new AllocaInst(CastElTy, Amt, Name);
InsertNewInstBefore(New, CI);
return ReplaceInstUsesWith(CI, New);
}
}
// If the source value is an instruction with only this use, we can attempt to
// propagate the cast into the instruction. Also, only handle integral types
// for now.
@ -1975,6 +2005,7 @@ void InstCombiner::removeFromWorkList(Instruction *I) {
bool InstCombiner::runOnFunction(Function &F) {
bool Changed = false;
TD = &getAnalysis<TargetData>();
WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));