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enhance heap-sra to apply to fixed sized array allocations, not just

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variable sized array allocations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61051 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-12-15 21:44:34 +00:00
parent 93b3b928d7
commit 101f44e81f
1 changed files with 43 additions and 4 deletions
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45
lib/Transforms/IPO/GlobalOpt.cpp
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@ -988,6 +988,23 @@ static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc,
// PHI.
unsigned PredNo = Alloc->use_begin().getOperandNo()/2;
InsertPt = PN->getIncomingBlock(PredNo)->getTerminator();
} else if (isa<BitCastInst>(U)) {
// Must be bitcast between the malloc and store to initialize the global.
ReplaceUsesOfMallocWithGlobal(U, GV);
U->eraseFromParent();
continue;
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) {
// If this is a "GEP bitcast" and the user is a store to the global, then
// just process it as a bitcast.
if (GEPI->hasAllZeroIndices() && GEPI->hasOneUse())
if (StoreInst *SI = dyn_cast<StoreInst>(GEPI->use_back()))
if (SI->getOperand(1) == GV) {
// Must be bitcast GEP between the malloc and store to initialize
// the global.
ReplaceUsesOfMallocWithGlobal(GEPI, GV);
GEPI->eraseFromParent();
continue;
}
}
// Insert a load from the global, and use it instead of the malloc.
@ -1339,12 +1356,34 @@ static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV,
// If the allocation is an array of structures, consider transforming this
// into multiple malloc'd arrays, one for each field. This is basically
// SRoA for malloc'd memory.
if (const StructType *AllocTy =
dyn_cast<StructType>(MI->getAllocatedType())) {
const Type *AllocTy = MI->getAllocatedType();
// If this is an allocation of a fixed size array of structs, analyze as a
// variable size array. malloc [100 x struct],1 -> malloc struct, 100
if (!MI->isArrayAllocation())
if (const ArrayType *AT = dyn_cast<ArrayType>(AllocTy))
AllocTy = AT->getElementType();
if (const StructType *AllocSTy = dyn_cast<StructType>(AllocTy)) {
// This the structure has an unreasonable number of fields, leave it
// alone.
if (AllocTy->getNumElements() <= 16 && AllocTy->getNumElements() > 0 &&
if (AllocSTy->getNumElements() <= 16 && AllocSTy->getNumElements() != 0 &&
GlobalLoadUsesSimpleEnoughForHeapSRA(GV, MI)) {
// If this is a fixed size array, transform the Malloc to be an alloc of
// structs. malloc [100 x struct],1 -> malloc struct, 100
if (const ArrayType *AT = dyn_cast<ArrayType>(MI->getAllocatedType())) {
MallocInst *NewMI =
new MallocInst(AllocSTy,
ConstantInt::get(Type::Int32Ty, AT->getNumElements()),
"", MI);
NewMI->takeName(MI);
Value *Cast = new BitCastInst(NewMI, MI->getType(), "tmp", MI);
MI->replaceAllUsesWith(Cast);
MI->eraseFromParent();
MI = NewMI;
}
GVI = PerformHeapAllocSRoA(GV, MI);
return true;
}