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Fix PR66 & ScalarRepl/2003-10-29-ArrayProblem.ll 

llvm-svn: 9585
This commit is contained in:
Chris Lattner 2003-10-29 17:55:44 +00:00
parent 9e761b40af
commit bcb0f4bf2e
1 changed files with 25 additions and 62 deletions
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87
llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
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@ -54,8 +54,7 @@ namespace {
private:
bool isSafeElementUse(Value *Ptr);
bool isSafeUseOfAllocation(Instruction *User);
bool isSafeStructAllocaToPromote(AllocationInst *AI);
bool isSafeArrayAllocaToPromote(AllocationInst *AI);
bool isSafeAllocaToPromote(AllocationInst *AI);
AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
};
@ -139,10 +138,7 @@ bool SROA::performScalarRepl(Function &F) {
// 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))
if (!isSafeAllocaToPromote(AI))
continue;
DEBUG(std::cerr << "Found inst to xform: " << *AI);
@ -230,10 +226,28 @@ bool SROA::isSafeUseOfAllocation(Instruction *User) {
!isa<Constant>(GEPI->getOperand(2)) ||
isa<ConstantExpr>(GEPI->getOperand(2)))
return false;
} else {
return false;
// If this is a use of an array allocation, do a bit more checking for
// sanity.
if (GEPI->getOperand(2)->getType() == Type::LongTy) {
const PointerType *PTy =cast<PointerType>(GEPI->getOperand(0)->getType());
const ArrayType *AT = cast<ArrayType>(PTy->getElementType());
int64_t NumElements = AT->getNumElements();
// 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 ||
cast<ConstantSInt>(GEPI->getOperand(2))->getValue() < 0)
return false;
}
// If there are any non-simple uses of this getelementptr, make sure to
// reject them.
if (isSafeElementUse(GEPI))
return true;
}
return true;
return false;
}
/// isSafeElementUse - Check to see if this use is an allowed use for a
@ -271,67 +285,16 @@ bool SROA::isSafeElementUse(Value *Ptr) {
/// isSafeStructAllocaToPromote - Check to see if the specified allocation of a
/// structure can be broken down into elements.
///
bool SROA::isSafeStructAllocaToPromote(AllocationInst *AI) {
bool SROA::isSafeAllocaToPromote(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) {
I != E; ++I)
if (!isSafeUseOfAllocation(cast<Instruction>(*I))) {
DEBUG(std::cerr << "Cannot transform: " << *AI << " due to user: "
<< *I);
return false;
}
// Pedantic check to avoid breaking broken programs...
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*I))
if (GEPI->getNumOperands() == 3 && !isSafeElementUse(GEPI))
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 (!isSafeElementUse(GEPI)) {
DEBUG(std::cerr << "Cannot transform: " << *AI
<< " due to uses of user: " << *GEPI);
return false;
}
}
}
return true;
}