1//===- CoroCleanup.cpp - Coroutine Cleanup Pass ---------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/Transforms/Coroutines/CoroCleanup.h"
10#include "CoroInternal.h"
11#include "llvm/IR/Function.h"
12#include "llvm/IR/IRBuilder.h"
13#include "llvm/IR/InstIterator.h"
14#include "llvm/IR/Module.h"
15#include "llvm/IR/PassManager.h"
16#include "llvm/Transforms/Scalar/SimplifyCFG.h"
17
18using namespace llvm;
19
20#define DEBUG_TYPE "coro-cleanup"
21
22namespace {
23// Created on demand if CoroCleanup pass has work to do.
24struct Lowerer : coro::LowererBase {
25 IRBuilder<> Builder;
26 Lowerer(Module &M) : LowererBase(M), Builder(Context) {}
27 bool lower(Function &F);
28};
29}
30
31static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
32 Builder.SetInsertPoint(SubFn);
33 Value *FramePtr = SubFn->getFrame();
34 int Index = SubFn->getIndex();
35
36 auto *FrameTy = StructType::get(Context&: SubFn->getContext(),
37 Elements: {Builder.getPtrTy(), Builder.getPtrTy()});
38
39 Builder.SetInsertPoint(SubFn);
40 auto *Gep = Builder.CreateConstInBoundsGEP2_32(Ty: FrameTy, Ptr: FramePtr, Idx0: 0, Idx1: Index);
41 auto *Load = Builder.CreateLoad(Ty: FrameTy->getElementType(N: Index), Ptr: Gep);
42
43 SubFn->replaceAllUsesWith(V: Load);
44}
45
46bool Lowerer::lower(Function &F) {
47 bool IsPrivateAndUnprocessed = F.isPresplitCoroutine() && F.hasLocalLinkage();
48 bool Changed = false;
49
50 for (Instruction &I : llvm::make_early_inc_range(Range: instructions(F))) {
51 if (auto *II = dyn_cast<IntrinsicInst>(Val: &I)) {
52 switch (II->getIntrinsicID()) {
53 default:
54 continue;
55 case Intrinsic::coro_begin:
56 II->replaceAllUsesWith(V: II->getArgOperand(i: 1));
57 break;
58 case Intrinsic::coro_free:
59 II->replaceAllUsesWith(V: II->getArgOperand(i: 1));
60 break;
61 case Intrinsic::coro_alloc:
62 II->replaceAllUsesWith(V: ConstantInt::getTrue(Context));
63 break;
64 case Intrinsic::coro_async_resume:
65 II->replaceAllUsesWith(
66 V: ConstantPointerNull::get(T: cast<PointerType>(Val: I.getType())));
67 break;
68 case Intrinsic::coro_id:
69 case Intrinsic::coro_id_retcon:
70 case Intrinsic::coro_id_retcon_once:
71 case Intrinsic::coro_id_async:
72 II->replaceAllUsesWith(V: ConstantTokenNone::get(Context));
73 break;
74 case Intrinsic::coro_subfn_addr:
75 lowerSubFn(Builder, SubFn: cast<CoroSubFnInst>(Val: II));
76 break;
77 case Intrinsic::coro_end:
78 case Intrinsic::coro_suspend_retcon:
79 if (IsPrivateAndUnprocessed) {
80 II->replaceAllUsesWith(V: UndefValue::get(T: II->getType()));
81 } else
82 continue;
83 break;
84 case Intrinsic::coro_async_size_replace:
85 auto *Target = cast<ConstantStruct>(
86 Val: cast<GlobalVariable>(Val: II->getArgOperand(i: 0)->stripPointerCasts())
87 ->getInitializer());
88 auto *Source = cast<ConstantStruct>(
89 Val: cast<GlobalVariable>(Val: II->getArgOperand(i: 1)->stripPointerCasts())
90 ->getInitializer());
91 auto *TargetSize = Target->getOperand(i_nocapture: 1);
92 auto *SourceSize = Source->getOperand(i_nocapture: 1);
93 if (TargetSize->isElementWiseEqual(Y: SourceSize)) {
94 break;
95 }
96 auto *TargetRelativeFunOffset = Target->getOperand(i_nocapture: 0);
97 auto *NewFuncPtrStruct = ConstantStruct::get(
98 T: Target->getType(), Vs: TargetRelativeFunOffset, Vs: SourceSize);
99 Target->replaceAllUsesWith(V: NewFuncPtrStruct);
100 break;
101 }
102 II->eraseFromParent();
103 Changed = true;
104 }
105 }
106
107 return Changed;
108}
109
110static bool declaresCoroCleanupIntrinsics(const Module &M) {
111 return coro::declaresIntrinsics(
112 M, {"llvm.coro.alloc", "llvm.coro.begin", "llvm.coro.subfn.addr",
113 "llvm.coro.free", "llvm.coro.id", "llvm.coro.id.retcon",
114 "llvm.coro.id.async", "llvm.coro.id.retcon.once",
115 "llvm.coro.async.size.replace", "llvm.coro.async.resume"});
116}
117
118PreservedAnalyses CoroCleanupPass::run(Module &M,
119 ModuleAnalysisManager &MAM) {
120 if (!declaresCoroCleanupIntrinsics(M))
121 return PreservedAnalyses::all();
122
123 FunctionAnalysisManager &FAM =
124 MAM.getResult<FunctionAnalysisManagerModuleProxy>(IR&: M).getManager();
125
126 FunctionPassManager FPM;
127 FPM.addPass(Pass: SimplifyCFGPass());
128
129 PreservedAnalyses FuncPA;
130 FuncPA.preserveSet<CFGAnalyses>();
131
132 Lowerer L(M);
133 for (auto &F : M) {
134 if (L.lower(F)) {
135 FAM.invalidate(IR&: F, PA: FuncPA);
136 FPM.run(IR&: F, AM&: FAM);
137 }
138 }
139
140 return PreservedAnalyses::none();
141}
142