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📄 ADCE.cpp(24.71 KB)
📄 AlignmentFromAssumptions.cpp(15.9 KB)
📄 BDCE.cpp(7.42 KB)
📄 CallSiteSplitting.cpp(21.43 KB)
📄 ConstantHoisting.cpp(38.95 KB)
📄 ConstantProp.cpp(4.13 KB)
📄 CorrelatedValuePropagation.cpp(32.36 KB)
📄 DCE.cpp(6.84 KB)
📄 DeadStoreElimination.cpp(91.51 KB)
📄 DivRemPairs.cpp(15.01 KB)
📄 EarlyCSE.cpp(57.05 KB)
📄 FlattenCFGPass.cpp(2.74 KB)
📄 Float2Int.cpp(18.19 KB)
📄 GVN.cpp(100.11 KB)
📄 GVNHoist.cpp(44.85 KB)
📄 GVNSink.cpp(29.97 KB)
📄 GuardWidening.cpp(32.36 KB)
📄 IVUsersPrinter.cpp(839 B)
📄 IndVarSimplify.cpp(113.49 KB)
📄 InductiveRangeCheckElimination.cpp(72.96 KB)
📄 InferAddressSpaces.cpp(44.22 KB)
📄 InstSimplifyPass.cpp(5.39 KB)
📄 JumpThreading.cpp(115.06 KB)
📄 LICM.cpp(92.71 KB)
📄 LoopAccessAnalysisPrinter.cpp(977 B)
📄 LoopDataPrefetch.cpp(14.54 KB)
📄 LoopDeletion.cpp(11.37 KB)
📄 LoopDistribute.cpp(40.25 KB)
📄 LoopFuse.cpp(68.6 KB)
📄 LoopIdiomRecognize.cpp(69.09 KB)
📄 LoopInstSimplify.cpp(9.38 KB)
📄 LoopInterchange.cpp(60.65 KB)
📄 LoopLoadElimination.cpp(26.71 KB)
📄 LoopPassManager.cpp(4.02 KB)
📄 LoopPredication.cpp(49.21 KB)
📄 LoopRerollPass.cpp(58.54 KB)
📄 LoopRotation.cpp(4.79 KB)
📄 LoopSimplifyCFG.cpp(28.59 KB)
📄 LoopSink.cpp(14.93 KB)
📄 LoopStrengthReduce.cpp(216.88 KB)
📄 LoopUnrollAndJamPass.cpp(21.07 KB)
📄 LoopUnrollPass.cpp(60.73 KB)
📄 LoopUnswitch.cpp(64.17 KB)
📄 LoopVersioningLICM.cpp(23.65 KB)
📄 LowerAtomic.cpp(5.12 KB)
📄 LowerConstantIntrinsics.cpp(5.8 KB)
📄 LowerExpectIntrinsic.cpp(15 KB)
📄 LowerGuardIntrinsic.cpp(2.82 KB)
📄 LowerMatrixIntrinsics.cpp(73.36 KB)
📄 LowerWidenableCondition.cpp(2.75 KB)
📄 MakeGuardsExplicit.cpp(3.83 KB)
📄 MemCpyOptimizer.cpp(52.16 KB)
📄 MergeICmps.cpp(35.61 KB)
📄 MergedLoadStoreMotion.cpp(15.18 KB)
📄 NaryReassociate.cpp(19.86 KB)
📄 NewGVN.cpp(170.95 KB)
📄 PartiallyInlineLibCalls.cpp(6.22 KB)
📄 PlaceSafepoints.cpp(27.5 KB)
📄 Reassociate.cpp(95.61 KB)
📄 Reg2Mem.cpp(4.34 KB)
📄 RewriteStatepointsForGC.cpp(116.35 KB)
📄 SCCP.cpp(76.12 KB)
📄 SROA.cpp(183.83 KB)
📄 Scalar.cpp(10.08 KB)
📄 Scalarizer.cpp(32.93 KB)
📄 SeparateConstOffsetFromGEP.cpp(52.99 KB)
📄 SimpleLoopUnswitch.cpp(124.57 KB)
📄 SimplifyCFGPass.cpp(12.31 KB)
📄 Sink.cpp(10.81 KB)
📄 SpeculateAroundPHIs.cpp(35.69 KB)
📄 SpeculativeExecution.cpp(11.54 KB)
📄 StraightLineStrengthReduce.cpp(28.92 KB)
📄 StructurizeCFG.cpp(32.49 KB)
📄 TailRecursionElimination.cpp(34.9 KB)
📄 WarnMissedTransforms.cpp(6.14 KB)

Editing: LowerAtomic.cpp

//===- LowerAtomic.cpp - Lower atomic intrinsics --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This pass lowers atomic intrinsics to non-atomic form for use in a known
// non-preemptible environment.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Scalar/LowerAtomic.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;

#define DEBUG_TYPE "loweratomic"

static bool LowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI) {
  IRBuilder<> Builder(CXI);
  Value *Ptr = CXI->getPointerOperand();
  Value *Cmp = CXI->getCompareOperand();
  Value *Val = CXI->getNewValOperand();

LoadInst *Orig = Builder.CreateLoad(Val->getType(), Ptr);
  Value *Equal = Builder.CreateICmpEQ(Orig, Cmp);
  Value *Res = Builder.CreateSelect(Equal, Val, Orig);
  Builder.CreateStore(Res, Ptr);

Res = Builder.CreateInsertValue(UndefValue::get(CXI->getType()), Orig, 0);
  Res = Builder.CreateInsertValue(Res, Equal, 1);

CXI->replaceAllUsesWith(Res);
  CXI->eraseFromParent();
  return true;
}

static bool LowerAtomicRMWInst(AtomicRMWInst *RMWI) {
  IRBuilder<> Builder(RMWI);
  Value *Ptr = RMWI->getPointerOperand();
  Value *Val = RMWI->getValOperand();

LoadInst *Orig = Builder.CreateLoad(Val->getType(), Ptr);
  Value *Res = nullptr;

switch (RMWI->getOperation()) {
  default: llvm_unreachable("Unexpected RMW operation");
  case AtomicRMWInst::Xchg:
    Res = Val;
    break;
  case AtomicRMWInst::Add:
    Res = Builder.CreateAdd(Orig, Val);
    break;
  case AtomicRMWInst::Sub:
    Res = Builder.CreateSub(Orig, Val);
    break;
  case AtomicRMWInst::And:
    Res = Builder.CreateAnd(Orig, Val);
    break;
  case AtomicRMWInst::Nand:
    Res = Builder.CreateNot(Builder.CreateAnd(Orig, Val));
    break;
  case AtomicRMWInst::Or:
    Res = Builder.CreateOr(Orig, Val);
    break;
  case AtomicRMWInst::Xor:
    Res = Builder.CreateXor(Orig, Val);
    break;
  case AtomicRMWInst::Max:
    Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Val),
                               Val, Orig);
    break;
  case AtomicRMWInst::Min:
    Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Val),
                               Orig, Val);
    break;
  case AtomicRMWInst::UMax:
    Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Val),
                               Val, Orig);
    break;
  case AtomicRMWInst::UMin:
    Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Val),
                               Orig, Val);
    break;
  case AtomicRMWInst::FAdd:
    Res = Builder.CreateFAdd(Orig, Val);
    break;
  case AtomicRMWInst::FSub:
    Res = Builder.CreateFSub(Orig, Val);
    break;
  }
  Builder.CreateStore(Res, Ptr);
  RMWI->replaceAllUsesWith(Orig);
  RMWI->eraseFromParent();
  return true;
}

static bool LowerFenceInst(FenceInst *FI) {
  FI->eraseFromParent();
  return true;
}

static bool LowerLoadInst(LoadInst *LI) {
  LI->setAtomic(AtomicOrdering::NotAtomic);
  return true;
}

static bool LowerStoreInst(StoreInst *SI) {
  SI->setAtomic(AtomicOrdering::NotAtomic);
  return true;
}

static bool runOnBasicBlock(BasicBlock &BB) {
  bool Changed = false;
  for (Instruction &Inst : make_early_inc_range(BB)) {
    if (FenceInst *FI = dyn_cast<FenceInst>(&Inst))
      Changed |= LowerFenceInst(FI);
    else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(&Inst))
      Changed |= LowerAtomicCmpXchgInst(CXI);
    else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(&Inst))
      Changed |= LowerAtomicRMWInst(RMWI);
    else if (LoadInst *LI = dyn_cast<LoadInst>(&Inst)) {
      if (LI->isAtomic())
        LowerLoadInst(LI);
    } else if (StoreInst *SI = dyn_cast<StoreInst>(&Inst)) {
      if (SI->isAtomic())
        LowerStoreInst(SI);
    }
  }
  return Changed;
}

static bool lowerAtomics(Function &F) {
  bool Changed = false;
  for (BasicBlock &BB : F) {
    Changed |= runOnBasicBlock(BB);
  }
  return Changed;
}

PreservedAnalyses LowerAtomicPass::run(Function &F, FunctionAnalysisManager &) {
  if (lowerAtomics(F))
    return PreservedAnalyses::none();
  return PreservedAnalyses::all();
}

namespace {
class LowerAtomicLegacyPass : public FunctionPass {
public:
  static char ID;

LowerAtomicLegacyPass() : FunctionPass(ID) {
    initializeLowerAtomicLegacyPassPass(*PassRegistry::getPassRegistry());
  }

bool runOnFunction(Function &F) override {
    // Don't skip optnone functions; atomics still need to be lowered.
    FunctionAnalysisManager DummyFAM;
    auto PA = Impl.run(F, DummyFAM);
    return !PA.areAllPreserved();
  }

private:
  LowerAtomicPass Impl;
  };
}

char LowerAtomicLegacyPass::ID = 0;
INITIALIZE_PASS(LowerAtomicLegacyPass, "loweratomic",
                "Lower atomic intrinsics to non-atomic form", false, false)

Pass *llvm::createLowerAtomicPass() { return new LowerAtomicLegacyPass(); }

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Editing: LowerAtomic.cpp

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