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Move the ConstantFoldLoadThroughGEPConstantExpr function out of the InstCombine

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pass.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23444 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-09-26 05:27:10 +00:00
parent c5406b55d5
commit c5f52e6da1
1 changed files with 45 additions and 1 deletions
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46
lib/Transforms/Utils/Local.cpp
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@ -12,11 +12,13 @@
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/MathExtras.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include <cerrno>
#include <cmath>
using namespace llvm;
@ -366,6 +368,48 @@ Constant *llvm::ConstantFoldCall(Function *F,
}
/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
/// getelementptr constantexpr, return the constant value being addressed by the
/// constant expression, or null if something is funny and we can't decide.
Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
ConstantExpr *CE) {
if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
return 0; // Do not allow stepping over the value!
// Loop over all of the operands, tracking down which value we are
// addressing...
gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
for (++I; I != E; ++I)
if (const StructType *STy = dyn_cast<StructType>(*I)) {
ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
assert(CU->getValue() < STy->getNumElements() &&
"Struct index out of range!");
unsigned El = (unsigned)CU->getValue();
if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
C = CS->getOperand(El);
} else if (isa<ConstantAggregateZero>(C)) {
C = Constant::getNullValue(STy->getElementType(El));
} else if (isa<UndefValue>(C)) {
C = UndefValue::get(STy->getElementType(El));
} else {
return 0;
}
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
const ArrayType *ATy = cast<ArrayType>(*I);
if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
C = CA->getOperand((unsigned)CI->getRawValue());
else if (isa<ConstantAggregateZero>(C))
C = Constant::getNullValue(ATy->getElementType());
else if (isa<UndefValue>(C))
C = UndefValue::get(ATy->getElementType());
else
return 0;
} else {
return 0;
}
return C;
}
//===----------------------------------------------------------------------===//