lib/IR/Operator.cpp

   1 //===-- Operator.cpp - Implement the LLVM operators -----------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the non-inline methods for the LLVM Operator classes.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/IR/Operator.h"
  15 #include "llvm/IR/DataLayout.h"
  16 #include "llvm/IR/GetElementPtrTypeIterator.h"
  17 #include "llvm/IR/Instructions.h"
  18 #include "llvm/IR/Type.h"
  19
  20 #include "ConstantsContext.h"
  21
  22 namespace llvm {
  23 Type *GEPOperator::getSourceElementType() const {
  24   if (auto *I = dyn_cast<GetElementPtrInst>(this))
  25     return I->getSourceElementType();
  26   return cast<GetElementPtrConstantExpr>(this)->getSourceElementType();
  27 }
  28
  29 Type *GEPOperator::getResultElementType() const {
  30   if (auto *I = dyn_cast<GetElementPtrInst>(this))
  31     return I->getResultElementType();
  32   return cast<GetElementPtrConstantExpr>(this)->getResultElementType();
  33 }
  34
  35 bool GEPOperator::accumulateConstantOffset(const DataLayout &DL,
  36                                            APInt &Offset) const {
  37   assert(Offset.getBitWidth() ==
  38              DL.getIndexSizeInBits(getPointerAddressSpace()) &&
  39          "The offset bit width does not match DL specification.");
  40
  41   for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this);
  42        GTI != GTE; ++GTI) {
  43     ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
  44     if (!OpC)
  45       return false;
  46     if (OpC->isZero())
  47       continue;
  48
  49     // Handle a struct index, which adds its field offset to the pointer.
  50     if (StructType *STy = GTI.getStructTypeOrNull()) {
  51       unsigned ElementIdx = OpC->getZExtValue();
  52       const StructLayout *SL = DL.getStructLayout(STy);
  53       Offset += APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
  54       continue;
  55     }
  56
  57     // For array or vector indices, scale the index by the size of the type.
  58     APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
  59     Offset += Index * APInt(Offset.getBitWidth(),
  60                             DL.getTypeAllocSize(GTI.getIndexedType()));
  61   }
  62   return true;
  63 }
  64 }