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Fix bug: ScalarRepl/2003-05-29-ArrayFail.ll

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6425 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-05-30 04:15:41 +00:00
parent 6607fbec94
commit 5e062a1eda
1 changed files with 128 additions and 42 deletions
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170
lib/Transforms/Scalar/ScalarReplAggregates.cpp
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@ -23,6 +23,10 @@ namespace {
bool runOnFunction(Function &F);
private:
bool isSafeArrayElementUse(Value *Ptr);
bool isSafeUseOfAllocation(Instruction *User);
bool isSafeStructAllocaToPromote(AllocationInst *AI);
bool isSafeArrayAllocaToPromote(AllocationInst *AI);
AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
};
@ -59,48 +63,13 @@ bool SROA::runOnFunction(Function &F) {
(!isa<StructType>(AI->getAllocatedType()) &&
!isa<ArrayType>(AI->getAllocatedType()))) continue;
const ArrayType *AT = dyn_cast<ArrayType>(AI->getAllocatedType());
// Loop over the use list of the alloca. We can only transform it if there
// are only getelementptr instructions (with a zero first index) and free
// instructions.
//
bool CannotTransform = false;
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
I != E; ++I) {
Instruction *User = cast<Instruction>(*I);
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
// The GEP is safe to transform if it is of the form GEP <ptr>, 0, <cst>
if (GEPI->getNumOperands() <= 2 ||
GEPI->getOperand(1) != Constant::getNullValue(Type::LongTy) ||
!isa<Constant>(GEPI->getOperand(2)) ||
isa<ConstantExpr>(GEPI->getOperand(2))) {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< User);
CannotTransform = true;
break;
}
// If this is an array access, check to make sure that index falls
// within the array. If not, something funny is going on, so we won't
// do the optimization.
if (AT && cast<ConstantSInt>(GEPI->getOperand(2))->getValue() >=
AT->getNumElements()) {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< User);
CannotTransform = true;
break;
}
} else {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< User);
CannotTransform = true;
break;
}
}
if (CannotTransform) continue;
// Check that all of the users of the allocation are capable of being
// transformed.
if (isa<StructType>(AI->getAllocatedType())) {
if (!isSafeStructAllocaToPromote(AI))
continue;
} else if (!isSafeArrayAllocaToPromote(AI))
continue;
DEBUG(std::cerr << "Found inst to xform: " << *AI);
Changed = true;
@ -115,6 +84,7 @@ bool SROA::runOnFunction(Function &F) {
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) {
@ -177,3 +147,119 @@ bool SROA::runOnFunction(Function &F) {
return Changed;
}
/// isSafeUseOfAllocation - Check to see if this user is an allowed use for an
/// aggregate allocation.
///
bool SROA::isSafeUseOfAllocation(Instruction *User) {
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
// The GEP is safe to transform if it is of the form GEP <ptr>, 0, <cst>
if (GEPI->getNumOperands() <= 2 ||
GEPI->getOperand(1) != Constant::getNullValue(Type::LongTy) ||
!isa<Constant>(GEPI->getOperand(2)) ||
isa<ConstantExpr>(GEPI->getOperand(2)))
return false;
} else {
return false;
}
return true;
}
/// isSafeArrayElementUse - Check to see if this use is an allowed use for a
/// getelementptr instruction of an array aggregate allocation.
///
bool SROA::isSafeArrayElementUse(Value *Ptr) {
for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
I != E; ++I) {
Instruction *User = cast<Instruction>(*I);
switch (User->getOpcode()) {
case Instruction::Load: return true;
case Instruction::Store: return User->getOperand(0) != Ptr;
case Instruction::GetElementPtr: {
GetElementPtrInst *GEP = cast<GetElementPtrInst>(User);
if (GEP->getNumOperands() > 1) {
if (!isa<Constant>(GEP->getOperand(1)) ||
!cast<Constant>(GEP->getOperand(1))->isNullValue())
return false; // Using pointer arithmetic to navigate the array...
// Check to see if there are any structure indexes involved in this GEP.
// If so, then we can safely break the array up until at least the
// structure.
for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
if (GEP->getOperand(i)->getType()->isUnsigned())
break;
}
return isSafeArrayElementUse(GEP);
}
default:
DEBUG(std::cerr << " Transformation preventing inst: " << *User);
return false;
}
}
return true; // All users look ok :)
}
/// isSafeStructAllocaToPromote - Check to see if the specified allocation of a
/// structure can be broken down into elements.
///
bool SROA::isSafeStructAllocaToPromote(AllocationInst *AI) {
// Loop over the use list of the alloca. We can only transform it if all of
// the users are safe to transform.
//
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
I != E; ++I)
if (!isSafeUseOfAllocation(cast<Instruction>(*I))) {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< *I);
return false;
}
return true;
}
/// isSafeArrayAllocaToPromote - Check to see if the specified allocation of a
/// structure can be broken down into elements.
///
bool SROA::isSafeArrayAllocaToPromote(AllocationInst *AI) {
const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
int64_t NumElements = AT->getNumElements();
// Loop over the use list of the alloca. We can only transform it if all of
// the users are safe to transform. Array allocas have extra constraints to
// meet though.
//
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
I != E; ++I) {
Instruction *User = cast<Instruction>(*I);
if (!isSafeUseOfAllocation(User)) {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< User);
return false;
}
// Check to make sure that getelementptr follow the extra rules for arrays:
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
// Check to make sure that index falls within the array. If not,
// something funny is going on, so we won't do the optimization.
//
if (cast<ConstantSInt>(GEPI->getOperand(2))->getValue() >= NumElements)
return false;
// Check to make sure that the only thing that uses the resultant pointer
// is safe for an array access. For example, code that looks like:
// P = &A[0]; P = P + 1
// is legal, and should prevent promotion.
//
if (!isSafeArrayElementUse(GEPI)) {
DEBUG(std::cerr << "Cannot transform: " << *AI
<< " due to uses of user: " << *GEPI);
return false;
}
}
}
return true;
}