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1 //===-- Operator.cpp - Implement the LLVM operators -----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the non-inline methods for the LLVM Operator classes.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/IR/Operator.h"
14 #include "llvm/IR/DataLayout.h"
15 #include "llvm/IR/GetElementPtrTypeIterator.h"
16 #include "llvm/IR/Instructions.h"
17 #include "llvm/IR/Type.h"
18 
19 #include "ConstantsContext.h"
20 
21 namespace llvm {
getSourceElementType() const22 Type *GEPOperator::getSourceElementType() const {
23   if (auto *I = dyn_cast<GetElementPtrInst>(this))
24     return I->getSourceElementType();
25   return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
26 }
27 
getResultElementType() const28 Type *GEPOperator::getResultElementType() const {
29   if (auto *I = dyn_cast<GetElementPtrInst>(this))
30     return I->getResultElementType();
31   return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
32 }
33 
accumulateConstantOffset(const DataLayout & DL,APInt & Offset) const34 bool GEPOperator::accumulateConstantOffset(const DataLayout &DL,
35                                            APInt &Offset) const {
36   assert(Offset.getBitWidth() ==
37              DL.getIndexSizeInBits(getPointerAddressSpace()) &&
38          "The offset bit width does not match DL specification.");
39 
40   for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
41        GTI != GTE; ++GTI) {
42     ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
43     if (!OpC)
44       return false;
45     if (OpC->isZero())
46       continue;
47 
48     // Handle a struct index, which adds its field offset to the pointer.
49     if (StructType *STy = GTI.getStructTypeOrNull()) {
50       unsigned ElementIdx = OpC->getZExtValue();
51       const StructLayout *SL = DL.getStructLayout(STy);
52       Offset += APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
53       continue;
54     }
55 
56     // For array or vector indices, scale the index by the size of the type.
57     APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
58     Offset += Index * APInt(Offset.getBitWidth(),
59                             DL.getTypeAllocSize(GTI.getIndexedType()));
60   }
61   return true;
62 }
63 }
64