CoroCleanup.cpp revision 360784 
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// This pass lowers all remaining coroutine intrinsics.
9//===----------------------------------------------------------------------===//
10
11#include "CoroInternal.h"
12#include "llvm/IR/IRBuilder.h"
13#include "llvm/IR/InstIterator.h"
14#include "llvm/IR/LegacyPassManager.h"
15#include "llvm/Pass.h"
16#include "llvm/Transforms/Scalar.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 lowerRemainingCoroIntrinsics(Function &F);
28};
29}
30
31static void simplifyCFG(Function &F) {
32  llvm::legacy::FunctionPassManager FPM(F.getParent());
33  FPM.add(createCFGSimplificationPass());
34
35  FPM.doInitialization();
36  FPM.run(F);
37  FPM.doFinalization();
38}
39
40static void lowerSubFn(IRBuilder<> &Builder, CoroSubFnInst *SubFn) {
41  Builder.SetInsertPoint(SubFn);
42  Value *FrameRaw = SubFn->getFrame();
43  int Index = SubFn->getIndex();
44
45  auto *FrameTy = StructType::get(
46      SubFn->getContext(), {Builder.getInt8PtrTy(), Builder.getInt8PtrTy()});
47  PointerType *FramePtrTy = FrameTy->getPointerTo();
48
49  Builder.SetInsertPoint(SubFn);
50  auto *FramePtr = Builder.CreateBitCast(FrameRaw, FramePtrTy);
51  auto *Gep = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index);
52  auto *Load = Builder.CreateLoad(FrameTy->getElementType(Index), Gep);
53
54  SubFn->replaceAllUsesWith(Load);
55}
56
57bool Lowerer::lowerRemainingCoroIntrinsics(Function &F) {
58  bool Changed = false;
59
60  for (auto IB = inst_begin(F), E = inst_end(F); IB != E;) {
61    Instruction &I = *IB++;
62    if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
63      switch (II->getIntrinsicID()) {
64      default:
65        continue;
66      case Intrinsic::coro_begin:
67        II->replaceAllUsesWith(II->getArgOperand(1));
68        break;
69      case Intrinsic::coro_free:
70        II->replaceAllUsesWith(II->getArgOperand(1));
71        break;
72      case Intrinsic::coro_alloc:
73        II->replaceAllUsesWith(ConstantInt::getTrue(Context));
74        break;
75      case Intrinsic::coro_id:
76      case Intrinsic::coro_id_retcon:
77      case Intrinsic::coro_id_retcon_once:
78        II->replaceAllUsesWith(ConstantTokenNone::get(Context));
79        break;
80      case Intrinsic::coro_subfn_addr:
81        lowerSubFn(Builder, cast<CoroSubFnInst>(II));
82        break;
83      }
84      II->eraseFromParent();
85      Changed = true;
86    }
87  }
88
89  if (Changed) {
90    // After replacement were made we can cleanup the function body a little.
91    simplifyCFG(F);
92  }
93  return Changed;
94}
95
96//===----------------------------------------------------------------------===//
97//                              Top Level Driver
98//===----------------------------------------------------------------------===//
99
100namespace {
101
102struct CoroCleanupLegacy : FunctionPass {
103  static char ID; // Pass identification, replacement for typeid
104
105  CoroCleanupLegacy() : FunctionPass(ID) {
106    initializeCoroCleanupLegacyPass(*PassRegistry::getPassRegistry());
107  }
108
109  std::unique_ptr<Lowerer> L;
110
111  // This pass has work to do only if we find intrinsics we are going to lower
112  // in the module.
113  bool doInitialization(Module &M) override {
114    if (coro::declaresIntrinsics(M, {"llvm.coro.alloc", "llvm.coro.begin",
115                                     "llvm.coro.subfn.addr", "llvm.coro.free",
116                                     "llvm.coro.id", "llvm.coro.id.retcon",
117                                     "llvm.coro.id.retcon.once"}))
118      L = std::make_unique<Lowerer>(M);
119    return false;
120  }
121
122  bool runOnFunction(Function &F) override {
123    if (L)
124      return L->lowerRemainingCoroIntrinsics(F);
125    return false;
126  }
127  void getAnalysisUsage(AnalysisUsage &AU) const override {
128    if (!L)
129      AU.setPreservesAll();
130  }
131  StringRef getPassName() const override { return "Coroutine Cleanup"; }
132};
133}
134
135char CoroCleanupLegacy::ID = 0;
136INITIALIZE_PASS(CoroCleanupLegacy, "coro-cleanup",
137                "Lower all coroutine related intrinsics", false, false)
138
139Pass *llvm::createCoroCleanupLegacyPass() { return new CoroCleanupLegacy(); }
140