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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
//
//===----------------------------------------------------------------------===//
// This pass lowers all remaining coroutine intrinsics.
//===----------------------------------------------------------------------===//
#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;
for (auto IB = inst_begin(F), E = inst_end(F); IB != E;) {
Instruction &I = *IB++;
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_id:
II->replaceAllUsesWith(ConstantTokenNone::get(Context));
break;
case Intrinsic::coro_subfn_addr:
lowerSubFn(Builder, cast<CoroSubFnInst>(II));
break;
}
II->eraseFromParent();
Changed = true;
}
}
if (Changed) {
// After replacement were made we can cleanup the function body a little.
simplifyCFG(F);
}
return Changed;
}
//===----------------------------------------------------------------------===//
// Top Level Driver
//===----------------------------------------------------------------------===//
namespace {
struct CoroCleanup : FunctionPass {
static char ID; // Pass identification, replacement for typeid
CoroCleanup() : FunctionPass(ID) {
initializeCoroCleanupPass(*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 (coro::declaresIntrinsics(M, {"llvm.coro.alloc", "llvm.coro.begin",
"llvm.coro.subfn.addr", "llvm.coro.free",
"llvm.coro.id"}))
L = llvm::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 CoroCleanup::ID = 0;
INITIALIZE_PASS(CoroCleanup, "coro-cleanup",
"Lower all coroutine related intrinsics", false, false)
Pass *llvm::createCoroCleanupPass() { return new CoroCleanup(); }
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