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refactor the SROA code out into its own method, no functionality change.

llvm-svn: 36426
This commit is contained in:
Chris Lattner 2007-04-25 05:02:56 +00:00
parent ca7480e8cb
commit cf27f9705f

View File

@ -65,6 +65,8 @@ namespace {
bool isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI); bool isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI);
bool isSafeUseOfBitCastedAllocation(BitCastInst *User, AllocationInst *AI); bool isSafeUseOfBitCastedAllocation(BitCastInst *User, AllocationInst *AI);
int isSafeAllocaToScalarRepl(AllocationInst *AI); int isSafeAllocaToScalarRepl(AllocationInst *AI);
void DoScalarReplacement(AllocationInst *AI,
std::vector<AllocationInst*> &WorkList);
void CanonicalizeAllocaUsers(AllocationInst *AI); void CanonicalizeAllocaUsers(AllocationInst *AI);
AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base); AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
@ -166,118 +168,125 @@ bool SROA::performScalarRepl(Function &F) {
// We cannot transform the allocation instruction if it is an array // We cannot transform the allocation instruction if it is an array
// allocation (allocations OF arrays are ok though), and an allocation of a // allocation (allocations OF arrays are ok though), and an allocation of a
// scalar value cannot be decomposed at all. // scalar value cannot be decomposed at all.
// if (!AI->isArrayAllocation() &&
if (AI->isArrayAllocation() || (isa<StructType>(AI->getAllocatedType()) ||
(!isa<StructType>(AI->getAllocatedType()) && isa<ArrayType>(AI->getAllocatedType()))) {
!isa<ArrayType>(AI->getAllocatedType()))) continue; // Check that all of the users of the allocation are capable of being
// transformed.
// Check that all of the users of the allocation are capable of being switch (isSafeAllocaToScalarRepl(AI)) {
// transformed. default: assert(0 && "Unexpected value!");
switch (isSafeAllocaToScalarRepl(AI)) { case 0: // Not safe to scalar replace.
default: assert(0 && "Unexpected value!"); break;
case 0: // Not safe to scalar replace. case 1: // Safe, but requires cleanup/canonicalizations first
continue; CanonicalizeAllocaUsers(AI);
case 1: // Safe, but requires cleanup/canonicalizations first // FALL THROUGH.
CanonicalizeAllocaUsers(AI); case 3: // Safe to scalar replace.
case 3: // Safe to scalar replace. DoScalarReplacement(AI, WorkList);
break; Changed = true;
}
DOUT << "Found inst to xform: " << *AI;
Changed = true;
SmallVector<AllocaInst*, 32> ElementAllocas;
if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
ElementAllocas.reserve(ST->getNumContainedTypes());
for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
AI->getAlignment(),
AI->getName() + "." + utostr(i), AI);
ElementAllocas.push_back(NA);
WorkList.push_back(NA); // Add to worklist for recursive processing
}
} else {
const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
ElementAllocas.reserve(AT->getNumElements());
const Type *ElTy = AT->getElementType();
for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(),
AI->getName() + "." + utostr(i), AI);
ElementAllocas.push_back(NA);
WorkList.push_back(NA); // Add to worklist for recursive processing
}
}
// Now that we have created the alloca instructions that we want to use,
// expand the getelementptr instructions to use them.
//
while (!AI->use_empty()) {
Instruction *User = cast<Instruction>(AI->use_back());
if (BitCastInst *BCInst = dyn_cast<BitCastInst>(User)) {
RewriteBitCastUserOfAlloca(BCInst, AI, ElementAllocas);
BCInst->eraseFromParent();
continue; continue;
} }
GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
// We now know that the GEP is of the form: GEP <ptr>, 0, <cst>
unsigned Idx =
(unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
assert(Idx < ElementAllocas.size() && "Index out of range?");
AllocaInst *AllocaToUse = ElementAllocas[Idx];
Value *RepValue;
if (GEPI->getNumOperands() == 3) {
// Do not insert a new getelementptr instruction with zero indices, only
// to have it optimized out later.
RepValue = AllocaToUse;
} else {
// We are indexing deeply into the structure, so we still need a
// getelement ptr instruction to finish the indexing. This may be
// expanded itself once the worklist is rerun.
//
SmallVector<Value*, 8> NewArgs;
NewArgs.push_back(Constant::getNullValue(Type::Int32Ty));
NewArgs.append(GEPI->op_begin()+3, GEPI->op_end());
RepValue = new GetElementPtrInst(AllocaToUse, &NewArgs[0],
NewArgs.size(), "", GEPI);
RepValue->takeName(GEPI);
}
// If this GEP is to the start of the aggregate, check for memcpys.
if (Idx == 0) {
bool IsStartOfAggregateGEP = true;
for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i) {
if (!isa<ConstantInt>(GEPI->getOperand(i))) {
IsStartOfAggregateGEP = false;
break;
}
if (!cast<ConstantInt>(GEPI->getOperand(i))->isZero()) {
IsStartOfAggregateGEP = false;
break;
}
}
if (IsStartOfAggregateGEP)
RewriteBitCastUserOfAlloca(GEPI, AI, ElementAllocas);
}
// Move all of the users over to the new GEP.
GEPI->replaceAllUsesWith(RepValue);
// Delete the old GEP
GEPI->eraseFromParent();
} }
// Finally, delete the Alloca instruction // Otherwise, couldn't process this.
AI->eraseFromParent();
NumReplaced++;
} }
return Changed; return Changed;
} }
/// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl
/// predicate, do SROA now.
void SROA::DoScalarReplacement(AllocationInst *AI,
std::vector<AllocationInst*> &WorkList) {
DOUT << "Found inst to xform: " << *AI;
SmallVector<AllocaInst*, 32> ElementAllocas;
if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
ElementAllocas.reserve(ST->getNumContainedTypes());
for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
AI->getAlignment(),
AI->getName() + "." + utostr(i), AI);
ElementAllocas.push_back(NA);
WorkList.push_back(NA); // Add to worklist for recursive processing
}
} else {
const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
ElementAllocas.reserve(AT->getNumElements());
const Type *ElTy = AT->getElementType();
for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(),
AI->getName() + "." + utostr(i), AI);
ElementAllocas.push_back(NA);
WorkList.push_back(NA); // Add to worklist for recursive processing
}
}
// Now that we have created the alloca instructions that we want to use,
// expand the getelementptr instructions to use them.
//
while (!AI->use_empty()) {
Instruction *User = cast<Instruction>(AI->use_back());
if (BitCastInst *BCInst = dyn_cast<BitCastInst>(User)) {
RewriteBitCastUserOfAlloca(BCInst, AI, ElementAllocas);
BCInst->eraseFromParent();
continue;
}
GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
// We now know that the GEP is of the form: GEP <ptr>, 0, <cst>
unsigned Idx =
(unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
assert(Idx < ElementAllocas.size() && "Index out of range?");
AllocaInst *AllocaToUse = ElementAllocas[Idx];
Value *RepValue;
if (GEPI->getNumOperands() == 3) {
// Do not insert a new getelementptr instruction with zero indices, only
// to have it optimized out later.
RepValue = AllocaToUse;
} else {
// We are indexing deeply into the structure, so we still need a
// getelement ptr instruction to finish the indexing. This may be
// expanded itself once the worklist is rerun.
//
SmallVector<Value*, 8> NewArgs;
NewArgs.push_back(Constant::getNullValue(Type::Int32Ty));
NewArgs.append(GEPI->op_begin()+3, GEPI->op_end());
RepValue = new GetElementPtrInst(AllocaToUse, &NewArgs[0],
NewArgs.size(), "", GEPI);
RepValue->takeName(GEPI);
}
// If this GEP is to the start of the aggregate, check for memcpys.
if (Idx == 0) {
bool IsStartOfAggregateGEP = true;
for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i) {
if (!isa<ConstantInt>(GEPI->getOperand(i))) {
IsStartOfAggregateGEP = false;
break;
}
if (!cast<ConstantInt>(GEPI->getOperand(i))->isZero()) {
IsStartOfAggregateGEP = false;
break;
}
}
if (IsStartOfAggregateGEP)
RewriteBitCastUserOfAlloca(GEPI, AI, ElementAllocas);
}
// Move all of the users over to the new GEP.
GEPI->replaceAllUsesWith(RepValue);
// Delete the old GEP
GEPI->eraseFromParent();
}
// Finally, delete the Alloca instruction
AI->eraseFromParent();
NumReplaced++;
}
/// isSafeElementUse - Check to see if this use is an allowed use for a /// isSafeElementUse - Check to see if this use is an allowed use for a
/// getelementptr instruction of an array aggregate allocation. isFirstElt /// getelementptr instruction of an array aggregate allocation. isFirstElt