1bdd1243dSDimitry Andric //===- Local.cpp - Functions to perform local transformations -------------===//
2bdd1243dSDimitry Andric //
3bdd1243dSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4bdd1243dSDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5bdd1243dSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6bdd1243dSDimitry Andric //
7bdd1243dSDimitry Andric //===----------------------------------------------------------------------===//
8bdd1243dSDimitry Andric //
9bdd1243dSDimitry Andric // This family of functions perform various local transformations to the
10bdd1243dSDimitry Andric // program.
11bdd1243dSDimitry Andric //
12bdd1243dSDimitry Andric //===----------------------------------------------------------------------===//
13bdd1243dSDimitry Andric
14bdd1243dSDimitry Andric #include "llvm/Analysis/Utils/Local.h"
15bdd1243dSDimitry Andric #include "llvm/ADT/Twine.h"
16bdd1243dSDimitry Andric #include "llvm/IR/DataLayout.h"
17bdd1243dSDimitry Andric #include "llvm/IR/GetElementPtrTypeIterator.h"
18bdd1243dSDimitry Andric #include "llvm/IR/IRBuilder.h"
19bdd1243dSDimitry Andric
20bdd1243dSDimitry Andric using namespace llvm;
21bdd1243dSDimitry Andric
emitGEPOffset(IRBuilderBase * Builder,const DataLayout & DL,User * GEP,bool NoAssumptions)22bdd1243dSDimitry Andric Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
23bdd1243dSDimitry Andric User *GEP, bool NoAssumptions) {
24bdd1243dSDimitry Andric GEPOperator *GEPOp = cast<GEPOperator>(GEP);
25bdd1243dSDimitry Andric Type *IntIdxTy = DL.getIndexType(GEP->getType());
26bdd1243dSDimitry Andric Value *Result = nullptr;
27bdd1243dSDimitry Andric
28bdd1243dSDimitry Andric // If the GEP is inbounds, we know that none of the addressing operations will
29bdd1243dSDimitry Andric // overflow in a signed sense.
30bdd1243dSDimitry Andric bool isInBounds = GEPOp->isInBounds() && !NoAssumptions;
315f757f3fSDimitry Andric auto AddOffset = [&](Value *Offset) {
325f757f3fSDimitry Andric if (Result)
335f757f3fSDimitry Andric Result = Builder->CreateAdd(Result, Offset, GEP->getName() + ".offs",
345f757f3fSDimitry Andric false /*NUW*/, isInBounds /*NSW*/);
355f757f3fSDimitry Andric else
365f757f3fSDimitry Andric Result = Offset;
375f757f3fSDimitry Andric };
38bdd1243dSDimitry Andric
39bdd1243dSDimitry Andric gep_type_iterator GTI = gep_type_begin(GEP);
40bdd1243dSDimitry Andric for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
41bdd1243dSDimitry Andric ++i, ++GTI) {
42bdd1243dSDimitry Andric Value *Op = *i;
43bdd1243dSDimitry Andric if (Constant *OpC = dyn_cast<Constant>(Op)) {
44bdd1243dSDimitry Andric if (OpC->isZeroValue())
45bdd1243dSDimitry Andric continue;
46bdd1243dSDimitry Andric
47bdd1243dSDimitry Andric // Handle a struct index, which adds its field offset to the pointer.
48bdd1243dSDimitry Andric if (StructType *STy = GTI.getStructTypeOrNull()) {
49bdd1243dSDimitry Andric uint64_t OpValue = OpC->getUniqueInteger().getZExtValue();
505f757f3fSDimitry Andric uint64_t Size = DL.getStructLayout(STy)->getElementOffset(OpValue);
51bdd1243dSDimitry Andric if (!Size)
52bdd1243dSDimitry Andric continue;
53bdd1243dSDimitry Andric
545f757f3fSDimitry Andric AddOffset(ConstantInt::get(IntIdxTy, Size));
555f757f3fSDimitry Andric continue;
56bdd1243dSDimitry Andric }
575f757f3fSDimitry Andric }
585f757f3fSDimitry Andric
59bdd1243dSDimitry Andric // Splat the index if needed.
60bdd1243dSDimitry Andric if (IntIdxTy->isVectorTy() && !Op->getType()->isVectorTy())
61bdd1243dSDimitry Andric Op = Builder->CreateVectorSplat(
625f757f3fSDimitry Andric cast<VectorType>(IntIdxTy)->getElementCount(), Op);
63bdd1243dSDimitry Andric
64bdd1243dSDimitry Andric // Convert to correct type.
65bdd1243dSDimitry Andric if (Op->getType() != IntIdxTy)
66bdd1243dSDimitry Andric Op = Builder->CreateIntCast(Op, IntIdxTy, true, Op->getName() + ".c");
67*1db9f3b2SDimitry Andric TypeSize TSize = GTI.getSequentialElementStride(DL);
685f757f3fSDimitry Andric if (TSize != TypeSize::getFixed(1)) {
695f757f3fSDimitry Andric Value *Scale = Builder->CreateTypeSize(IntIdxTy->getScalarType(), TSize);
705f757f3fSDimitry Andric if (IntIdxTy->isVectorTy())
715f757f3fSDimitry Andric Scale = Builder->CreateVectorSplat(
725f757f3fSDimitry Andric cast<VectorType>(IntIdxTy)->getElementCount(), Scale);
73bdd1243dSDimitry Andric // We'll let instcombine(mul) convert this to a shl if possible.
745f757f3fSDimitry Andric Op = Builder->CreateMul(Op, Scale, GEP->getName() + ".idx", false /*NUW*/,
75bdd1243dSDimitry Andric isInBounds /*NSW*/);
76bdd1243dSDimitry Andric }
775f757f3fSDimitry Andric AddOffset(Op);
78bdd1243dSDimitry Andric }
79bdd1243dSDimitry Andric return Result ? Result : Constant::getNullValue(IntIdxTy);
80bdd1243dSDimitry Andric }
81