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//===- CoroCleanup.cpp - Coroutine Cleanup Pass ---------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Coroutines/CoroCleanup.h"
#include "CoroInternal.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;
#define DEBUG_TYPE "coro-cleanup"
namespace {
// Created on demand if CoroCleanup pass has work to do.
struct Lowerer : coro::LowererBase {
IRBuilder<> Builder;
Lowerer(Module &M) : LowererBase(M), Builder(Context) {}
bool lowerRemainingCoroIntrinsics(Function &F);
};
}
static void simplifyCFG(Function &F) {
llvm::legacy::FunctionPassManager FPM(F.getParent());
FPM.add(createCFGSimplificationPass());
FPM.doInitialization();
FPM.run(F);
FPM.doFinalization();
}
static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
Builder.SetInsertPoint(SubFn);
Value *FrameRaw = SubFn->getFrame();
int Index = SubFn->getIndex();
auto *FrameTy = StructType::get(
SubFn->getContext(), {Builder.getInt8PtrTy(), Builder.getInt8PtrTy()});
PointerType *FramePtrTy = FrameTy->getPointerTo();
Builder.SetInsertPoint(SubFn);
auto *FramePtr = Builder.CreateBitCast(FrameRaw, FramePtrTy);
auto *Gep = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index);
auto *Load = Builder.CreateLoad(FrameTy->getElementType(Index), Gep);
SubFn->replaceAllUsesWith(Load);
}
bool Lowerer::lowerRemainingCoroIntrinsics(Function &F) {
bool Changed = false;
bool IsPrivateAndUnprocessed =
F.hasFnAttribute(CORO_PRESPLIT_ATTR) && F.hasLocalLinkage();
for (Instruction &I : llvm::make_early_inc_range(instructions(F))) {
if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
switch (II->getIntrinsicID()) {
default:
continue;
case Intrinsic::coro_begin:
II->replaceAllUsesWith(II->getArgOperand(1));
break;
case Intrinsic::coro_free:
II->replaceAllUsesWith(II->getArgOperand(1));
break;
case Intrinsic::coro_alloc:
II->replaceAllUsesWith(ConstantInt::getTrue(Context));
break;
case Intrinsic::coro_async_resume:
II->replaceAllUsesWith(
ConstantPointerNull::get(cast<PointerType>(I.getType())));
break;
case Intrinsic::coro_id:
case Intrinsic::coro_id_retcon:
case Intrinsic::coro_id_retcon_once:
case Intrinsic::coro_id_async:
II->replaceAllUsesWith(ConstantTokenNone::get(Context));
break;
case Intrinsic::coro_subfn_addr:
lowerSubFn(Builder, cast<CoroSubFnInst>(II));
break;
case Intrinsic::coro_end:
case Intrinsic::coro_suspend_retcon:
if (IsPrivateAndUnprocessed) {
II->replaceAllUsesWith(UndefValue::get(II->getType()));
} else
continue;
break;
case Intrinsic::coro_async_size_replace:
auto *Target = cast<ConstantStruct>(
cast<GlobalVariable>(II->getArgOperand(0)->stripPointerCasts())
->getInitializer());
auto *Source = cast<ConstantStruct>(
cast<GlobalVariable>(II->getArgOperand(1)->stripPointerCasts())
->getInitializer());
auto *TargetSize = Target->getOperand(1);
auto *SourceSize = Source->getOperand(1);
if (TargetSize->isElementWiseEqual(SourceSize)) {
break;
}
auto *TargetRelativeFunOffset = Target->getOperand(0);
auto *NewFuncPtrStruct = ConstantStruct::get(
Target->getType(), TargetRelativeFunOffset, SourceSize);
Target->replaceAllUsesWith(NewFuncPtrStruct);
break;
}
II->eraseFromParent();
Changed = true;
}
}
if (Changed) {
// After replacement were made we can cleanup the function body a little.
simplifyCFG(F);
}
return Changed;
}
static bool declaresCoroCleanupIntrinsics(const Module &M) {
return coro::declaresIntrinsics(
M, {"llvm.coro.alloc", "llvm.coro.begin", "llvm.coro.subfn.addr",
"llvm.coro.free", "llvm.coro.id", "llvm.coro.id.retcon",
"llvm.coro.id.retcon.once", "llvm.coro.async.size.replace",
"llvm.coro.async.resume"});
}
PreservedAnalyses CoroCleanupPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &M = *F.getParent();
if (!declaresCoroCleanupIntrinsics(M) ||
!Lowerer(M).lowerRemainingCoroIntrinsics(F))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
namespace {
struct CoroCleanupLegacy : FunctionPass {
static char ID; // Pass identification, replacement for typeid
CoroCleanupLegacy() : FunctionPass(ID) {
initializeCoroCleanupLegacyPass(*PassRegistry::getPassRegistry());
}
std::unique_ptr<Lowerer> L;
// This pass has work to do only if we find intrinsics we are going to lower
// in the module.
bool doInitialization(Module &M) override {
if (declaresCoroCleanupIntrinsics(M))
L = std::make_unique<Lowerer>(M);
return false;
}
bool runOnFunction(Function &F) override {
if (L)
return L->lowerRemainingCoroIntrinsics(F);
return false;
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
if (!L)
AU.setPreservesAll();
}
StringRef getPassName() const override { return "Coroutine Cleanup"; }
};
}
char CoroCleanupLegacy::ID = 0;
INITIALIZE_PASS(CoroCleanupLegacy, "coro-cleanup",
"Lower all coroutine related intrinsics", false, false)
Pass *llvm::createCoroCleanupLegacyPass() { return new CoroCleanupLegacy(); }
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