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 18 using namespace llvm; 19 20 #define DEBUG_TYPE "coro-cleanup" 21 22 namespace { 23 // Created on demand if CoroCleanup pass has work to do. 24 struct Lowerer : coro::LowererBase { 25 IRBuilder<> Builder; 26 Lowerer(Module &M) : LowererBase(M), Builder(Context) {} 27 bool lowerRemainingCoroIntrinsics(Function &F); 28 }; 29 } 30 31 static 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 40 static 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 57 bool 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 II->replaceAllUsesWith(ConstantTokenNone::get(Context)); 77 break; 78 case Intrinsic::coro_subfn_addr: 79 lowerSubFn(Builder, cast<CoroSubFnInst>(II)); 80 break; 81 } 82 II->eraseFromParent(); 83 Changed = true; 84 } 85 } 86 87 if (Changed) { 88 // After replacement were made we can cleanup the function body a little. 89 simplifyCFG(F); 90 } 91 return Changed; 92 } 93 94 //===----------------------------------------------------------------------===// 95 // Top Level Driver 96 //===----------------------------------------------------------------------===// 97 98 namespace { 99 100 struct CoroCleanup : FunctionPass { 101 static char ID; // Pass identification, replacement for typeid 102 103 CoroCleanup() : FunctionPass(ID) { 104 initializeCoroCleanupPass(*PassRegistry::getPassRegistry()); 105 } 106 107 std::unique_ptr<Lowerer> L; 108 109 // This pass has work to do only if we find intrinsics we are going to lower 110 // in the module. 111 bool doInitialization(Module &M) override { 112 if (coro::declaresIntrinsics(M, {"llvm.coro.alloc", "llvm.coro.begin", 113 "llvm.coro.subfn.addr", "llvm.coro.free", 114 "llvm.coro.id"})) 115 L = llvm::make_unique<Lowerer>(M); 116 return false; 117 } 118 119 bool runOnFunction(Function &F) override { 120 if (L) 121 return L->lowerRemainingCoroIntrinsics(F); 122 return false; 123 } 124 void getAnalysisUsage(AnalysisUsage &AU) const override { 125 if (!L) 126 AU.setPreservesAll(); 127 } 128 StringRef getPassName() const override { return "Coroutine Cleanup"; } 129 }; 130 } 131 132 char CoroCleanup::ID = 0; 133 INITIALIZE_PASS(CoroCleanup, "coro-cleanup", 134 "Lower all coroutine related intrinsics", false, false) 135 136 Pass *llvm::createCoroCleanupPass() { return new CoroCleanup(); } 137