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Add helper function.

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Don't touch GEPs for which DecomposeArrayRef is not going to do anything
special (e.g., < 2 indices, or 2 indices and the last one is a constant.)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14647 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Brian Gaeke 2004-07-06 18:15:39 +00:00
parent a9e7781b3b
commit 10585d92da
1 changed files with 14 additions and 2 deletions
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16
lib/Transforms/Scalar/DecomposeMultiDimRefs.cpp
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@ -24,6 +24,7 @@
#include "llvm/BasicBlock.h"
#include "llvm/Pass.h"
#include "Support/Statistic.h"
#include "Support/Debug.h"
using namespace llvm;
namespace {
@ -52,6 +53,10 @@ FunctionPass *llvm::createDecomposeMultiDimRefsPass() {
return new DecomposePass();
}
static inline bool isZeroConst (Value *V) {
return isa<Constant> (V) && (cast<Constant>(V)->isNullValue());
}
// Function: DecomposeArrayRef()
//
// For any GetElementPtrInst with 2 or more array and structure indices:
@ -76,8 +81,15 @@ FunctionPass *llvm::createDecomposeMultiDimRefsPass() {
// Return value: true if the instruction was replaced; false otherwise.
//
bool llvm::DecomposeArrayRef(GetElementPtrInst* GEP) {
if (GEP->getNumIndices() < 2)
if (GEP->getNumIndices() < 2
|| (GEP->getNumIndices() == 2
&& isZeroConst(GEP->getOperand(1))
&& isa<ConstantInt>(GEP->getOperand(2)))) {
DEBUG (std::cerr << "DecomposeArrayRef: Skipping " << *GEP);
return false;
} else {
DEBUG (std::cerr << "DecomposeArrayRef: Decomposing " << *GEP);
}
BasicBlock *BB = GEP->getParent();
Value *LastPtr = GEP->getPointerOperand();
@ -90,7 +102,7 @@ bool llvm::DecomposeArrayRef(GetElementPtrInst* GEP) {
// If this is the first index and is 0, skip it and move on!
if (OI == GEP->idx_begin()) {
if (*OI == ConstantInt::getNullValue((*OI)->getType()))
if (isZeroConst (*OI))
continue;
}
else // Not the first index: include initial [0] to deref the last ptr