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1 #include "llvm/IR/Operator.h"
2 #include "llvm/IR/GetElementPtrTypeIterator.h"
3 #include "llvm/IR/Instructions.h"
4 #include "llvm/IR/Type.h"
5 
6 #include "ConstantsContext.h"
7 
8 namespace llvm {
getSourceElementType() const9 Type *GEPOperator::getSourceElementType() const {
10   if (auto *I = dyn_cast<GetElementPtrInst>(this))
11     return I->getSourceElementType();
12   return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
13 }
14 
accumulateConstantOffset(const DataLayout & DL,APInt & Offset) const15 bool GEPOperator::accumulateConstantOffset(const DataLayout &DL,
16                                            APInt &Offset) const {
17   assert(Offset.getBitWidth() ==
18              DL.getPointerSizeInBits(getPointerAddressSpace()) &&
19          "The offset must have exactly as many bits as our pointer.");
20 
21   for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
22        GTI != GTE; ++GTI) {
23     ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
24     if (!OpC)
25       return false;
26     if (OpC->isZero())
27       continue;
28 
29     // Handle a struct index, which adds its field offset to the pointer.
30     if (StructType *STy = dyn_cast<StructType>(*GTI)) {
31       unsigned ElementIdx = OpC->getZExtValue();
32       const StructLayout *SL = DL.getStructLayout(STy);
33       Offset += APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
34       continue;
35     }
36 
37     // For array or vector indices, scale the index by the size of the type.
38     APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
39     Offset += Index * APInt(Offset.getBitWidth(),
40                             DL.getTypeAllocSize(GTI.getIndexedType()));
41   }
42   return true;
43 }
44 }
45