| //===- Coroutines.cpp -----------------------------------------------------===// |
| // |
| // 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 file implements the common infrastructure for Coroutine Passes. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/Coroutines.h" |
| #include "llvm-c/Transforms/Coroutines.h" |
| #include "CoroInstr.h" |
| #include "CoroInternal.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/Analysis/CallGraph.h" |
| #include "llvm/Analysis/CallGraphSCCPass.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/IR/Attributes.h" |
| #include "llvm/IR/CallSite.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/DerivedTypes.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/InstIterator.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/Intrinsics.h" |
| #include "llvm/IR/LegacyPassManager.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/Type.h" |
| #include "llvm/Support/Casting.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Transforms/IPO.h" |
| #include "llvm/Transforms/IPO/PassManagerBuilder.h" |
| #include <cassert> |
| #include <cstddef> |
| #include <utility> |
| |
| using namespace llvm; |
| |
| void llvm::initializeCoroutines(PassRegistry &Registry) { |
| initializeCoroEarlyPass(Registry); |
| initializeCoroSplitPass(Registry); |
| initializeCoroElidePass(Registry); |
| initializeCoroCleanupPass(Registry); |
| } |
| |
| static void addCoroutineOpt0Passes(const PassManagerBuilder &Builder, |
| legacy::PassManagerBase &PM) { |
| PM.add(createCoroSplitPass()); |
| PM.add(createCoroElidePass()); |
| |
| PM.add(createBarrierNoopPass()); |
| PM.add(createCoroCleanupPass()); |
| } |
| |
| static void addCoroutineEarlyPasses(const PassManagerBuilder &Builder, |
| legacy::PassManagerBase &PM) { |
| PM.add(createCoroEarlyPass()); |
| } |
| |
| static void addCoroutineScalarOptimizerPasses(const PassManagerBuilder &Builder, |
| legacy::PassManagerBase &PM) { |
| PM.add(createCoroElidePass()); |
| } |
| |
| static void addCoroutineSCCPasses(const PassManagerBuilder &Builder, |
| legacy::PassManagerBase &PM) { |
| PM.add(createCoroSplitPass()); |
| } |
| |
| static void addCoroutineOptimizerLastPasses(const PassManagerBuilder &Builder, |
| legacy::PassManagerBase &PM) { |
| PM.add(createCoroCleanupPass()); |
| } |
| |
| void llvm::addCoroutinePassesToExtensionPoints(PassManagerBuilder &Builder) { |
| Builder.addExtension(PassManagerBuilder::EP_EarlyAsPossible, |
| addCoroutineEarlyPasses); |
| Builder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0, |
| addCoroutineOpt0Passes); |
| Builder.addExtension(PassManagerBuilder::EP_CGSCCOptimizerLate, |
| addCoroutineSCCPasses); |
| Builder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate, |
| addCoroutineScalarOptimizerPasses); |
| Builder.addExtension(PassManagerBuilder::EP_OptimizerLast, |
| addCoroutineOptimizerLastPasses); |
| } |
| |
| // Construct the lowerer base class and initialize its members. |
| coro::LowererBase::LowererBase(Module &M) |
| : TheModule(M), Context(M.getContext()), |
| Int8Ptr(Type::getInt8PtrTy(Context)), |
| ResumeFnType(FunctionType::get(Type::getVoidTy(Context), Int8Ptr, |
| /*isVarArg=*/false)), |
| NullPtr(ConstantPointerNull::get(Int8Ptr)) {} |
| |
| // Creates a sequence of instructions to obtain a resume function address using |
| // llvm.coro.subfn.addr. It generates the following sequence: |
| // |
| // call i8* @llvm.coro.subfn.addr(i8* %Arg, i8 %index) |
| // bitcast i8* %2 to void(i8*)* |
| |
| Value *coro::LowererBase::makeSubFnCall(Value *Arg, int Index, |
| Instruction *InsertPt) { |
| auto *IndexVal = ConstantInt::get(Type::getInt8Ty(Context), Index); |
| auto *Fn = Intrinsic::getDeclaration(&TheModule, Intrinsic::coro_subfn_addr); |
| |
| assert(Index >= CoroSubFnInst::IndexFirst && |
| Index < CoroSubFnInst::IndexLast && |
| "makeSubFnCall: Index value out of range"); |
| auto *Call = CallInst::Create(Fn, {Arg, IndexVal}, "", InsertPt); |
| |
| auto *Bitcast = |
| new BitCastInst(Call, ResumeFnType->getPointerTo(), "", InsertPt); |
| return Bitcast; |
| } |
| |
| #ifndef NDEBUG |
| static bool isCoroutineIntrinsicName(StringRef Name) { |
| // NOTE: Must be sorted! |
| static const char *const CoroIntrinsics[] = { |
| "llvm.coro.alloc", "llvm.coro.begin", "llvm.coro.destroy", |
| "llvm.coro.done", "llvm.coro.end", "llvm.coro.frame", |
| "llvm.coro.free", "llvm.coro.id", "llvm.coro.noop", |
| "llvm.coro.param", "llvm.coro.promise", "llvm.coro.resume", |
| "llvm.coro.save", "llvm.coro.size", "llvm.coro.subfn.addr", |
| "llvm.coro.suspend", |
| }; |
| return Intrinsic::lookupLLVMIntrinsicByName(CoroIntrinsics, Name) != -1; |
| } |
| #endif |
| |
| // Verifies if a module has named values listed. Also, in debug mode verifies |
| // that names are intrinsic names. |
| bool coro::declaresIntrinsics(Module &M, |
| std::initializer_list<StringRef> List) { |
| for (StringRef Name : List) { |
| assert(isCoroutineIntrinsicName(Name) && "not a coroutine intrinsic"); |
| if (M.getNamedValue(Name)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| // Replace all coro.frees associated with the provided CoroId either with 'null' |
| // if Elide is true and with its frame parameter otherwise. |
| void coro::replaceCoroFree(CoroIdInst *CoroId, bool Elide) { |
| SmallVector<CoroFreeInst *, 4> CoroFrees; |
| for (User *U : CoroId->users()) |
| if (auto CF = dyn_cast<CoroFreeInst>(U)) |
| CoroFrees.push_back(CF); |
| |
| if (CoroFrees.empty()) |
| return; |
| |
| Value *Replacement = |
| Elide ? ConstantPointerNull::get(Type::getInt8PtrTy(CoroId->getContext())) |
| : CoroFrees.front()->getFrame(); |
| |
| for (CoroFreeInst *CF : CoroFrees) { |
| CF->replaceAllUsesWith(Replacement); |
| CF->eraseFromParent(); |
| } |
| } |
| |
| // FIXME: This code is stolen from CallGraph::addToCallGraph(Function *F), which |
| // happens to be private. It is better for this functionality exposed by the |
| // CallGraph. |
| static void buildCGN(CallGraph &CG, CallGraphNode *Node) { |
| Function *F = Node->getFunction(); |
| |
| // Look for calls by this function. |
| for (Instruction &I : instructions(F)) |
| if (CallSite CS = CallSite(cast<Value>(&I))) { |
| const Function *Callee = CS.getCalledFunction(); |
| if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID())) |
| // Indirect calls of intrinsics are not allowed so no need to check. |
| // We can be more precise here by using TargetArg returned by |
| // Intrinsic::isLeaf. |
| Node->addCalledFunction(CS, CG.getCallsExternalNode()); |
| else if (!Callee->isIntrinsic()) |
| Node->addCalledFunction(CS, CG.getOrInsertFunction(Callee)); |
| } |
| } |
| |
| // Rebuild CGN after we extracted parts of the code from ParentFunc into |
| // NewFuncs. Builds CGNs for the NewFuncs and adds them to the current SCC. |
| void coro::updateCallGraph(Function &ParentFunc, ArrayRef<Function *> NewFuncs, |
| CallGraph &CG, CallGraphSCC &SCC) { |
| // Rebuild CGN from scratch for the ParentFunc |
| auto *ParentNode = CG[&ParentFunc]; |
| ParentNode->removeAllCalledFunctions(); |
| buildCGN(CG, ParentNode); |
| |
| SmallVector<CallGraphNode *, 8> Nodes(SCC.begin(), SCC.end()); |
| |
| for (Function *F : NewFuncs) { |
| CallGraphNode *Callee = CG.getOrInsertFunction(F); |
| Nodes.push_back(Callee); |
| buildCGN(CG, Callee); |
| } |
| |
| SCC.initialize(Nodes); |
| } |
| |
| static void clear(coro::Shape &Shape) { |
| Shape.CoroBegin = nullptr; |
| Shape.CoroEnds.clear(); |
| Shape.CoroSizes.clear(); |
| Shape.CoroSuspends.clear(); |
| |
| Shape.FrameTy = nullptr; |
| Shape.FramePtr = nullptr; |
| Shape.AllocaSpillBlock = nullptr; |
| Shape.ResumeSwitch = nullptr; |
| Shape.PromiseAlloca = nullptr; |
| Shape.HasFinalSuspend = false; |
| } |
| |
| static CoroSaveInst *createCoroSave(CoroBeginInst *CoroBegin, |
| CoroSuspendInst *SuspendInst) { |
| Module *M = SuspendInst->getModule(); |
| auto *Fn = Intrinsic::getDeclaration(M, Intrinsic::coro_save); |
| auto *SaveInst = |
| cast<CoroSaveInst>(CallInst::Create(Fn, CoroBegin, "", SuspendInst)); |
| assert(!SuspendInst->getCoroSave()); |
| SuspendInst->setArgOperand(0, SaveInst); |
| return SaveInst; |
| } |
| |
| // Collect "interesting" coroutine intrinsics. |
| void coro::Shape::buildFrom(Function &F) { |
| size_t FinalSuspendIndex = 0; |
| clear(*this); |
| SmallVector<CoroFrameInst *, 8> CoroFrames; |
| SmallVector<CoroSaveInst *, 2> UnusedCoroSaves; |
| |
| for (Instruction &I : instructions(F)) { |
| if (auto II = dyn_cast<IntrinsicInst>(&I)) { |
| switch (II->getIntrinsicID()) { |
| default: |
| continue; |
| case Intrinsic::coro_size: |
| CoroSizes.push_back(cast<CoroSizeInst>(II)); |
| break; |
| case Intrinsic::coro_frame: |
| CoroFrames.push_back(cast<CoroFrameInst>(II)); |
| break; |
| case Intrinsic::coro_save: |
| // After optimizations, coro_suspends using this coro_save might have |
| // been removed, remember orphaned coro_saves to remove them later. |
| if (II->use_empty()) |
| UnusedCoroSaves.push_back(cast<CoroSaveInst>(II)); |
| break; |
| case Intrinsic::coro_suspend: |
| CoroSuspends.push_back(cast<CoroSuspendInst>(II)); |
| if (CoroSuspends.back()->isFinal()) { |
| if (HasFinalSuspend) |
| report_fatal_error( |
| "Only one suspend point can be marked as final"); |
| HasFinalSuspend = true; |
| FinalSuspendIndex = CoroSuspends.size() - 1; |
| } |
| break; |
| case Intrinsic::coro_begin: { |
| auto CB = cast<CoroBeginInst>(II); |
| if (CB->getId()->getInfo().isPreSplit()) { |
| if (CoroBegin) |
| report_fatal_error( |
| "coroutine should have exactly one defining @llvm.coro.begin"); |
| CB->addAttribute(AttributeList::ReturnIndex, Attribute::NonNull); |
| CB->addAttribute(AttributeList::ReturnIndex, Attribute::NoAlias); |
| CB->removeAttribute(AttributeList::FunctionIndex, |
| Attribute::NoDuplicate); |
| CoroBegin = CB; |
| } |
| break; |
| } |
| case Intrinsic::coro_end: |
| CoroEnds.push_back(cast<CoroEndInst>(II)); |
| if (CoroEnds.back()->isFallthrough()) { |
| // Make sure that the fallthrough coro.end is the first element in the |
| // CoroEnds vector. |
| if (CoroEnds.size() > 1) { |
| if (CoroEnds.front()->isFallthrough()) |
| report_fatal_error( |
| "Only one coro.end can be marked as fallthrough"); |
| std::swap(CoroEnds.front(), CoroEnds.back()); |
| } |
| } |
| break; |
| } |
| } |
| } |
| |
| // If for some reason, we were not able to find coro.begin, bailout. |
| if (!CoroBegin) { |
| // Replace coro.frame which are supposed to be lowered to the result of |
| // coro.begin with undef. |
| auto *Undef = UndefValue::get(Type::getInt8PtrTy(F.getContext())); |
| for (CoroFrameInst *CF : CoroFrames) { |
| CF->replaceAllUsesWith(Undef); |
| CF->eraseFromParent(); |
| } |
| |
| // Replace all coro.suspend with undef and remove related coro.saves if |
| // present. |
| for (CoroSuspendInst *CS : CoroSuspends) { |
| CS->replaceAllUsesWith(UndefValue::get(CS->getType())); |
| CS->eraseFromParent(); |
| if (auto *CoroSave = CS->getCoroSave()) |
| CoroSave->eraseFromParent(); |
| } |
| |
| // Replace all coro.ends with unreachable instruction. |
| for (CoroEndInst *CE : CoroEnds) |
| changeToUnreachable(CE, /*UseLLVMTrap=*/false); |
| |
| return; |
| } |
| |
| // The coro.free intrinsic is always lowered to the result of coro.begin. |
| for (CoroFrameInst *CF : CoroFrames) { |
| CF->replaceAllUsesWith(CoroBegin); |
| CF->eraseFromParent(); |
| } |
| |
| // Canonicalize coro.suspend by inserting a coro.save if needed. |
| for (CoroSuspendInst *CS : CoroSuspends) |
| if (!CS->getCoroSave()) |
| createCoroSave(CoroBegin, CS); |
| |
| // Move final suspend to be the last element in the CoroSuspends vector. |
| if (HasFinalSuspend && |
| FinalSuspendIndex != CoroSuspends.size() - 1) |
| std::swap(CoroSuspends[FinalSuspendIndex], CoroSuspends.back()); |
| |
| // Remove orphaned coro.saves. |
| for (CoroSaveInst *CoroSave : UnusedCoroSaves) |
| CoroSave->eraseFromParent(); |
| } |
| |
| void LLVMAddCoroEarlyPass(LLVMPassManagerRef PM) { |
| unwrap(PM)->add(createCoroEarlyPass()); |
| } |
| |
| void LLVMAddCoroSplitPass(LLVMPassManagerRef PM) { |
| unwrap(PM)->add(createCoroSplitPass()); |
| } |
| |
| void LLVMAddCoroElidePass(LLVMPassManagerRef PM) { |
| unwrap(PM)->add(createCoroElidePass()); |
| } |
| |
| void LLVMAddCoroCleanupPass(LLVMPassManagerRef PM) { |
| unwrap(PM)->add(createCoroCleanupPass()); |
| } |