98 lines
3.4 KiB
C++
98 lines
3.4 KiB
C++
//===- LowerAtomic.cpp - Lower atomic intrinsics --------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass lowers atomic intrinsics to non-atomic form for use in a known
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// non-preemptible environment.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/LowerAtomic.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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using namespace llvm;
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#define DEBUG_TYPE "loweratomic"
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bool llvm::lowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI) {
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IRBuilder<> Builder(CXI);
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Value *Ptr = CXI->getPointerOperand();
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Value *Cmp = CXI->getCompareOperand();
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Value *Val = CXI->getNewValOperand();
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LoadInst *Orig = Builder.CreateLoad(Val->getType(), Ptr);
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Value *Equal = Builder.CreateICmpEQ(Orig, Cmp);
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Value *Res = Builder.CreateSelect(Equal, Val, Orig);
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Builder.CreateStore(Res, Ptr);
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Res = Builder.CreateInsertValue(PoisonValue::get(CXI->getType()), Orig, 0);
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Res = Builder.CreateInsertValue(Res, Equal, 1);
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CXI->replaceAllUsesWith(Res);
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CXI->eraseFromParent();
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return true;
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}
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Value *llvm::buildAtomicRMWValue(AtomicRMWInst::BinOp Op,
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IRBuilderBase &Builder, Value *Loaded,
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Value *Inc) {
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Value *NewVal;
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switch (Op) {
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case AtomicRMWInst::Xchg:
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return Inc;
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case AtomicRMWInst::Add:
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return Builder.CreateAdd(Loaded, Inc, "new");
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case AtomicRMWInst::Sub:
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return Builder.CreateSub(Loaded, Inc, "new");
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case AtomicRMWInst::And:
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return Builder.CreateAnd(Loaded, Inc, "new");
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case AtomicRMWInst::Nand:
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return Builder.CreateNot(Builder.CreateAnd(Loaded, Inc), "new");
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case AtomicRMWInst::Or:
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return Builder.CreateOr(Loaded, Inc, "new");
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case AtomicRMWInst::Xor:
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return Builder.CreateXor(Loaded, Inc, "new");
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case AtomicRMWInst::Max:
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NewVal = Builder.CreateICmpSGT(Loaded, Inc);
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return Builder.CreateSelect(NewVal, Loaded, Inc, "new");
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case AtomicRMWInst::Min:
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NewVal = Builder.CreateICmpSLE(Loaded, Inc);
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return Builder.CreateSelect(NewVal, Loaded, Inc, "new");
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case AtomicRMWInst::UMax:
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NewVal = Builder.CreateICmpUGT(Loaded, Inc);
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return Builder.CreateSelect(NewVal, Loaded, Inc, "new");
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case AtomicRMWInst::UMin:
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NewVal = Builder.CreateICmpULE(Loaded, Inc);
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return Builder.CreateSelect(NewVal, Loaded, Inc, "new");
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case AtomicRMWInst::FAdd:
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return Builder.CreateFAdd(Loaded, Inc, "new");
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case AtomicRMWInst::FSub:
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return Builder.CreateFSub(Loaded, Inc, "new");
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case AtomicRMWInst::FMax:
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return Builder.CreateMaxNum(Loaded, Inc);
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case AtomicRMWInst::FMin:
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return Builder.CreateMinNum(Loaded, Inc);
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default:
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llvm_unreachable("Unknown atomic op");
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}
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}
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bool llvm::lowerAtomicRMWInst(AtomicRMWInst *RMWI) {
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IRBuilder<> Builder(RMWI);
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Value *Ptr = RMWI->getPointerOperand();
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Value *Val = RMWI->getValOperand();
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LoadInst *Orig = Builder.CreateLoad(Val->getType(), Ptr);
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Value *Res = buildAtomicRMWValue(RMWI->getOperation(), Builder, Orig, Val);
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Builder.CreateStore(Res, Ptr);
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RMWI->replaceAllUsesWith(Orig);
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RMWI->eraseFromParent();
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return true;
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}
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