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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/PassManager.h"
#include "llvm/IR/Function.h"
#include "llvm/Transforms/Scalar/SimplifyCFG.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 lower(Function &F);
};
}
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::lower(Function &F) {
bool IsPrivateAndUnprocessed = F.isPresplitCoroutine() && F.hasLocalLinkage();
bool Changed = false;
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;
}
}
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(Module &M,
ModuleAnalysisManager &MAM) {
if (!declaresCoroCleanupIntrinsics(M))
return PreservedAnalyses::all();
FunctionAnalysisManager &FAM =
MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
FunctionPassManager FPM;
FPM.addPass(SimplifyCFGPass());
Lowerer L(M);
for (auto &F : M)
if (L.lower(F))
FPM.run(F, FAM);
return PreservedAnalyses::none();
}
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