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https://github.com/c64scene-ar/llvm-6502.git
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2684ddd72e
Ideally only those transform passes that run at -O0 remain enabled, in reality we get as close as we reasonably can. Passes are responsible for disabling themselves, it's not the job of the pass manager to do it for them. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200892 91177308-0d34-0410-b5e6-96231b3b80d8
145 lines
4.3 KiB
C++
145 lines
4.3 KiB
C++
//===- LowerAtomic.cpp - Lower atomic intrinsics --------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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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#define DEBUG_TYPE "loweratomic"
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#include "llvm/Transforms/Scalar.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/IR/IntrinsicInst.h"
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#include "llvm/Pass.h"
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using namespace llvm;
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static bool LowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI) {
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IRBuilder<> Builder(CXI->getParent(), 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(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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CXI->replaceAllUsesWith(Orig);
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CXI->eraseFromParent();
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return true;
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}
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static bool LowerAtomicRMWInst(AtomicRMWInst *RMWI) {
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IRBuilder<> Builder(RMWI->getParent(), 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(Ptr);
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Value *Res = NULL;
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switch (RMWI->getOperation()) {
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default: llvm_unreachable("Unexpected RMW operation");
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case AtomicRMWInst::Xchg:
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Res = Val;
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break;
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case AtomicRMWInst::Add:
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Res = Builder.CreateAdd(Orig, Val);
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break;
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case AtomicRMWInst::Sub:
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Res = Builder.CreateSub(Orig, Val);
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break;
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case AtomicRMWInst::And:
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Res = Builder.CreateAnd(Orig, Val);
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break;
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case AtomicRMWInst::Nand:
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Res = Builder.CreateNot(Builder.CreateAnd(Orig, Val));
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break;
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case AtomicRMWInst::Or:
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Res = Builder.CreateOr(Orig, Val);
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break;
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case AtomicRMWInst::Xor:
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Res = Builder.CreateXor(Orig, Val);
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break;
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case AtomicRMWInst::Max:
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Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Val),
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Val, Orig);
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break;
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case AtomicRMWInst::Min:
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Res = Builder.CreateSelect(Builder.CreateICmpSLT(Orig, Val),
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Orig, Val);
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break;
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case AtomicRMWInst::UMax:
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Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Val),
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Val, Orig);
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break;
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case AtomicRMWInst::UMin:
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Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Val),
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Orig, Val);
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break;
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}
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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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static bool LowerFenceInst(FenceInst *FI) {
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FI->eraseFromParent();
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return true;
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}
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static bool LowerLoadInst(LoadInst *LI) {
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LI->setAtomic(NotAtomic);
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return true;
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}
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static bool LowerStoreInst(StoreInst *SI) {
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SI->setAtomic(NotAtomic);
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return true;
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}
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namespace {
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struct LowerAtomic : public BasicBlockPass {
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static char ID;
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LowerAtomic() : BasicBlockPass(ID) {
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initializeLowerAtomicPass(*PassRegistry::getPassRegistry());
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}
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bool runOnBasicBlock(BasicBlock &BB) {
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if (skipOptnoneFunction(BB))
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return false;
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bool Changed = false;
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for (BasicBlock::iterator DI = BB.begin(), DE = BB.end(); DI != DE; ) {
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Instruction *Inst = DI++;
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if (FenceInst *FI = dyn_cast<FenceInst>(Inst))
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Changed |= LowerFenceInst(FI);
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else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(Inst))
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Changed |= LowerAtomicCmpXchgInst(CXI);
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else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(Inst))
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Changed |= LowerAtomicRMWInst(RMWI);
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else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
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if (LI->isAtomic())
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LowerLoadInst(LI);
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} else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
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if (SI->isAtomic())
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LowerStoreInst(SI);
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}
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}
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return Changed;
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}
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};
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}
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char LowerAtomic::ID = 0;
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INITIALIZE_PASS(LowerAtomic, "loweratomic",
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"Lower atomic intrinsics to non-atomic form",
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false, false)
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Pass *llvm::createLowerAtomicPass() { return new LowerAtomic(); }
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