llvm/lib/IR/Operator.cpp
Peter Collingbourne 06115803f9 IR: Change the gep_type_iterator API to avoid always exposing the "current" type.
Instead, expose whether the current type is an array or a struct, if an array
what the upper bound is, and if a struct the struct type itself. This is
in preparation for a later change which will make PointerType derive from
Type rather than SequentialType.

Differential Revision: https://reviews.llvm.org/D26594

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288458 91177308-0d34-0410-b5e6-96231b3b80d8
2016-12-02 02:24:42 +00:00

51 lines
1.7 KiB
C++

#include "llvm/IR/Operator.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Type.h"
#include "ConstantsContext.h"
namespace llvm {
Type *GEPOperator::getSourceElementType() const {
if (auto *I = dyn_cast<GetElementPtrInst>(this))
return I->getSourceElementType();
return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
}
Type *GEPOperator::getResultElementType() const {
if (auto *I = dyn_cast<GetElementPtrInst>(this))
return I->getResultElementType();
return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
}
bool GEPOperator::accumulateConstantOffset(const DataLayout &DL,
APInt &Offset) const {
assert(Offset.getBitWidth() ==
DL.getPointerSizeInBits(getPointerAddressSpace()) &&
"The offset must have exactly as many bits as our pointer.");
for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
GTI != GTE; ++GTI) {
ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
if (!OpC)
return false;
if (OpC->isZero())
continue;
// Handle a struct index, which adds its field offset to the pointer.
if (StructType *STy = GTI.getStructTypeOrNull()) {
unsigned ElementIdx = OpC->getZExtValue();
const StructLayout *SL = DL.getStructLayout(STy);
Offset += APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
continue;
}
// For array or vector indices, scale the index by the size of the type.
APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
Offset += Index * APInt(Offset.getBitWidth(),
DL.getTypeAllocSize(GTI.getIndexedType()));
}
return true;
}
}