80 lines · cpp
1//===- Local.cpp - Functions to perform local transformations -------------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This family of functions perform various local transformations to the10// program.11//12//===----------------------------------------------------------------------===//13 14#include "llvm/Analysis/Utils/Local.h"15#include "llvm/ADT/Twine.h"16#include "llvm/IR/DataLayout.h"17#include "llvm/IR/GetElementPtrTypeIterator.h"18#include "llvm/IR/IRBuilder.h"19 20using namespace llvm;21 22Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,23 User *GEP, bool NoAssumptions) {24 GEPOperator *GEPOp = cast<GEPOperator>(GEP);25 Type *IntIdxTy = DL.getIndexType(GEP->getType());26 Value *Result = nullptr;27 28 // nusw implies nsw for the offset arithmetic.29 bool NSW = GEPOp->hasNoUnsignedSignedWrap() && !NoAssumptions;30 bool NUW = GEPOp->hasNoUnsignedWrap() && !NoAssumptions;31 auto AddOffset = [&](Value *Offset) {32 if (Result)33 Result = Builder->CreateAdd(Result, Offset, GEP->getName() + ".offs",34 NUW, NSW);35 else36 Result = Offset;37 };38 39 gep_type_iterator GTI = gep_type_begin(GEP);40 for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;41 ++i, ++GTI) {42 Value *Op = *i;43 if (Constant *OpC = dyn_cast<Constant>(Op)) {44 if (OpC->isZeroValue())45 continue;46 47 // Handle a struct index, which adds its field offset to the pointer.48 if (StructType *STy = GTI.getStructTypeOrNull()) {49 uint64_t OpValue = OpC->getUniqueInteger().getZExtValue();50 uint64_t Size = DL.getStructLayout(STy)->getElementOffset(OpValue);51 if (!Size)52 continue;53 54 AddOffset(ConstantInt::get(IntIdxTy, Size));55 continue;56 }57 }58 59 // Splat the index if needed.60 if (IntIdxTy->isVectorTy() && !Op->getType()->isVectorTy())61 Op = Builder->CreateVectorSplat(62 cast<VectorType>(IntIdxTy)->getElementCount(), Op);63 64 // Convert to correct type.65 if (Op->getType() != IntIdxTy)66 Op = Builder->CreateIntCast(Op, IntIdxTy, true, Op->getName() + ".c");67 TypeSize TSize = GTI.getSequentialElementStride(DL);68 if (TSize != TypeSize::getFixed(1)) {69 Value *Scale = Builder->CreateTypeSize(IntIdxTy->getScalarType(), TSize);70 if (IntIdxTy->isVectorTy())71 Scale = Builder->CreateVectorSplat(72 cast<VectorType>(IntIdxTy)->getElementCount(), Scale);73 // We'll let instcombine(mul) convert this to a shl if possible.74 Op = Builder->CreateMul(Op, Scale, GEP->getName() + ".idx", NUW, NSW);75 }76 AddOffset(Op);77 }78 return Result ? Result : Constant::getNullValue(IntIdxTy);79}80