lib/IR/Operator.cpp

   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 {
  22 Type *GEPOperator::getSourceElementType() const {
  23   if (auto *I = dyn_cast<GetElementPtrInst>(this))
  24     return I->getSourceElementType();
  25   return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
  26 }
  27
  28 Type *GEPOperator::getResultElementType() const {
  29   if (auto *I = dyn_cast<GetElementPtrInst>(this))
  30     return I->getResultElementType();
  31   return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
  32 }
  33
  34 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 }