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https://github.com/llvm/llvm-project.git
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b311756450
This reverts commit 8bd1f9116aab879183f34707e6d21c7051d083b6. It appears that the commit broke msan bots.
1045 lines
39 KiB
C++
1045 lines
39 KiB
C++
//===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with C++ code generation of coroutines.
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//
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//===----------------------------------------------------------------------===//
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#include "CGCleanup.h"
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#include "CodeGenFunction.h"
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#include "llvm/ADT/ScopeExit.h"
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#include "clang/AST/StmtCXX.h"
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#include "clang/AST/StmtVisitor.h"
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using namespace clang;
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using namespace CodeGen;
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using llvm::Value;
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using llvm::BasicBlock;
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namespace {
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enum class AwaitKind { Init, Normal, Yield, Final };
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static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
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"final"};
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}
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struct clang::CodeGen::CGCoroData {
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// What is the current await expression kind and how many
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// await/yield expressions were encountered so far.
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// These are used to generate pretty labels for await expressions in LLVM IR.
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AwaitKind CurrentAwaitKind = AwaitKind::Init;
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unsigned AwaitNum = 0;
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unsigned YieldNum = 0;
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// How many co_return statements are in the coroutine. Used to decide whether
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// we need to add co_return; equivalent at the end of the user authored body.
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unsigned CoreturnCount = 0;
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// A branch to this block is emitted when coroutine needs to suspend.
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llvm::BasicBlock *SuspendBB = nullptr;
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// The promise type's 'unhandled_exception' handler, if it defines one.
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Stmt *ExceptionHandler = nullptr;
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// A temporary i1 alloca that stores whether 'await_resume' threw an
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// exception. If it did, 'true' is stored in this variable, and the coroutine
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// body must be skipped. If the promise type does not define an exception
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// handler, this is null.
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llvm::Value *ResumeEHVar = nullptr;
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// Stores the jump destination just before the coroutine memory is freed.
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// This is the destination that every suspend point jumps to for the cleanup
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// branch.
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CodeGenFunction::JumpDest CleanupJD;
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// Stores the jump destination just before the final suspend. The co_return
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// statements jumps to this point after calling return_xxx promise member.
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CodeGenFunction::JumpDest FinalJD;
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// Stores the llvm.coro.id emitted in the function so that we can supply it
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// as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
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// Note: llvm.coro.id returns a token that cannot be directly expressed in a
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// builtin.
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llvm::CallInst *CoroId = nullptr;
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// Stores the llvm.coro.begin emitted in the function so that we can replace
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// all coro.frame intrinsics with direct SSA value of coro.begin that returns
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// the address of the coroutine frame of the current coroutine.
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llvm::CallInst *CoroBegin = nullptr;
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// Stores the last emitted coro.free for the deallocate expressions, we use it
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// to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
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llvm::CallInst *LastCoroFree = nullptr;
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// If coro.id came from the builtin, remember the expression to give better
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// diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
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// EmitCoroutineBody.
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CallExpr const *CoroIdExpr = nullptr;
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};
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// Defining these here allows to keep CGCoroData private to this file.
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clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
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CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
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static void createCoroData(CodeGenFunction &CGF,
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CodeGenFunction::CGCoroInfo &CurCoro,
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llvm::CallInst *CoroId,
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CallExpr const *CoroIdExpr = nullptr) {
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if (CurCoro.Data) {
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if (CurCoro.Data->CoroIdExpr)
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CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
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"only one __builtin_coro_id can be used in a function");
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else if (CoroIdExpr)
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CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
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"__builtin_coro_id shall not be used in a C++ coroutine");
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else
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llvm_unreachable("EmitCoroutineBodyStatement called twice?");
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return;
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}
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CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
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CurCoro.Data->CoroId = CoroId;
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CurCoro.Data->CoroIdExpr = CoroIdExpr;
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}
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// Synthesize a pretty name for a suspend point.
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static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
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unsigned No = 0;
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switch (Kind) {
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case AwaitKind::Init:
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case AwaitKind::Final:
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break;
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case AwaitKind::Normal:
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No = ++Coro.AwaitNum;
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break;
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case AwaitKind::Yield:
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No = ++Coro.YieldNum;
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break;
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}
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SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
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if (No > 1) {
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Twine(No).toVector(Prefix);
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}
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return Prefix;
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}
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// Check if function can throw based on prototype noexcept, also works for
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// destructors which are implicitly noexcept but can be marked noexcept(false).
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static bool FunctionCanThrow(const FunctionDecl *D) {
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const auto *Proto = D->getType()->getAs<FunctionProtoType>();
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if (!Proto) {
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// Function proto is not found, we conservatively assume throwing.
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return true;
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}
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return !isNoexceptExceptionSpec(Proto->getExceptionSpecType()) ||
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Proto->canThrow() != CT_Cannot;
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}
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static bool StmtCanThrow(const Stmt *S) {
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if (const auto *CE = dyn_cast<CallExpr>(S)) {
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const auto *Callee = CE->getDirectCallee();
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if (!Callee)
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// We don't have direct callee. Conservatively assume throwing.
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return true;
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if (FunctionCanThrow(Callee))
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return true;
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// Fall through to visit the children.
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}
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if (const auto *TE = dyn_cast<CXXBindTemporaryExpr>(S)) {
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// Special handling of CXXBindTemporaryExpr here as calling of Dtor of the
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// temporary is not part of `children()` as covered in the fall through.
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// We need to mark entire statement as throwing if the destructor of the
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// temporary throws.
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const auto *Dtor = TE->getTemporary()->getDestructor();
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if (FunctionCanThrow(Dtor))
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return true;
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// Fall through to visit the children.
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}
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for (const auto *child : S->children())
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if (StmtCanThrow(child))
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return true;
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return false;
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}
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// Emit suspend expression which roughly looks like:
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//
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// auto && x = CommonExpr();
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// if (!x.await_ready()) {
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// llvm_coro_save();
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// llvm_coro_await_suspend(&x, frame, wrapper) (*) (**)
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// llvm_coro_suspend(); (***)
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// }
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// x.await_resume();
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//
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// where the result of the entire expression is the result of x.await_resume()
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//
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// (*) llvm_coro_await_suspend_{void, bool, handle} is lowered to
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// wrapper(&x, frame) when it's certain not to interfere with
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// coroutine transform. await_suspend expression is
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// asynchronous to the coroutine body and not all analyses
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// and transformations can handle it correctly at the moment.
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//
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// Wrapper function encapsulates x.await_suspend(...) call and looks like:
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//
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// auto __await_suspend_wrapper(auto& awaiter, void* frame) {
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// std::coroutine_handle<> handle(frame);
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// return awaiter.await_suspend(handle);
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// }
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//
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// (**) If x.await_suspend return type is bool, it allows to veto a suspend:
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// if (x.await_suspend(...))
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// llvm_coro_suspend();
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//
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// (***) llvm_coro_suspend() encodes three possible continuations as
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// a switch instruction:
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//
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// %where-to = call i8 @llvm.coro.suspend(...)
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// switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
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// i8 0, label %yield.ready ; go here when resumed
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// i8 1, label %yield.cleanup ; go here when destroyed
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// ]
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//
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// See llvm's docs/Coroutines.rst for more details.
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//
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namespace {
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struct LValueOrRValue {
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LValue LV;
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RValue RV;
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};
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}
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static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
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CoroutineSuspendExpr const &S,
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AwaitKind Kind, AggValueSlot aggSlot,
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bool ignoreResult, bool forLValue) {
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auto *E = S.getCommonExpr();
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auto CommonBinder =
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CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
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auto UnbindCommonOnExit =
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llvm::make_scope_exit([&] { CommonBinder.unbind(CGF); });
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auto Prefix = buildSuspendPrefixStr(Coro, Kind);
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BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
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BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
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BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
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// If expression is ready, no need to suspend.
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CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
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// Otherwise, emit suspend logic.
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CGF.EmitBlock(SuspendBlock);
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auto &Builder = CGF.Builder;
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llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
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auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
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auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
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auto SuspendWrapper = CodeGenFunction(CGF.CGM).generateAwaitSuspendWrapper(
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CGF.CurFn->getName(), Prefix, S);
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CGF.CurCoro.InSuspendBlock = true;
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assert(CGF.CurCoro.Data && CGF.CurCoro.Data->CoroBegin &&
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"expected to be called in coroutine context");
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SmallVector<llvm::Value *, 3> SuspendIntrinsicCallArgs;
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SuspendIntrinsicCallArgs.push_back(
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CGF.getOrCreateOpaqueLValueMapping(S.getOpaqueValue()).getPointer(CGF));
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SuspendIntrinsicCallArgs.push_back(CGF.CurCoro.Data->CoroBegin);
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SuspendIntrinsicCallArgs.push_back(SuspendWrapper);
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const auto SuspendReturnType = S.getSuspendReturnType();
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llvm::Intrinsic::ID AwaitSuspendIID;
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switch (SuspendReturnType) {
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case CoroutineSuspendExpr::SuspendReturnType::SuspendVoid:
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AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_void;
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break;
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case CoroutineSuspendExpr::SuspendReturnType::SuspendBool:
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AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_bool;
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break;
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case CoroutineSuspendExpr::SuspendReturnType::SuspendHandle:
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AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_handle;
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break;
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}
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llvm::Function *AwaitSuspendIntrinsic = CGF.CGM.getIntrinsic(AwaitSuspendIID);
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const auto AwaitSuspendCanThrow = StmtCanThrow(S.getSuspendExpr());
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llvm::CallBase *SuspendRet = nullptr;
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// FIXME: add call attributes?
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if (AwaitSuspendCanThrow)
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SuspendRet =
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CGF.EmitCallOrInvoke(AwaitSuspendIntrinsic, SuspendIntrinsicCallArgs);
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else
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SuspendRet = CGF.EmitNounwindRuntimeCall(AwaitSuspendIntrinsic,
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SuspendIntrinsicCallArgs);
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assert(SuspendRet);
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CGF.CurCoro.InSuspendBlock = false;
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switch (SuspendReturnType) {
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case CoroutineSuspendExpr::SuspendReturnType::SuspendVoid:
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assert(SuspendRet->getType()->isVoidTy());
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break;
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case CoroutineSuspendExpr::SuspendReturnType::SuspendBool: {
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assert(SuspendRet->getType()->isIntegerTy());
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// Veto suspension if requested by bool returning await_suspend.
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BasicBlock *RealSuspendBlock =
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CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
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CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
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CGF.EmitBlock(RealSuspendBlock);
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break;
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}
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case CoroutineSuspendExpr::SuspendReturnType::SuspendHandle: {
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assert(SuspendRet->getType()->isPointerTy());
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auto ResumeIntrinsic = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_resume);
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Builder.CreateCall(ResumeIntrinsic, SuspendRet);
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break;
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}
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}
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// Emit the suspend point.
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const bool IsFinalSuspend = (Kind == AwaitKind::Final);
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llvm::Function *CoroSuspend =
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CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
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auto *SuspendResult = Builder.CreateCall(
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CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
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// Create a switch capturing three possible continuations.
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auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
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Switch->addCase(Builder.getInt8(0), ReadyBlock);
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Switch->addCase(Builder.getInt8(1), CleanupBlock);
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// Emit cleanup for this suspend point.
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CGF.EmitBlock(CleanupBlock);
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CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
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// Emit await_resume expression.
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CGF.EmitBlock(ReadyBlock);
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// Exception handling requires additional IR. If the 'await_resume' function
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// is marked as 'noexcept', we avoid generating this additional IR.
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CXXTryStmt *TryStmt = nullptr;
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if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
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StmtCanThrow(S.getResumeExpr())) {
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Coro.ResumeEHVar =
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CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
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Builder.CreateFlagStore(true, Coro.ResumeEHVar);
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auto Loc = S.getResumeExpr()->getExprLoc();
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auto *Catch = new (CGF.getContext())
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CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
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auto *TryBody = CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(),
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FPOptionsOverride(), Loc, Loc);
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TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
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CGF.EnterCXXTryStmt(*TryStmt);
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CGF.EmitStmt(TryBody);
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// We don't use EmitCXXTryStmt here. We need to store to ResumeEHVar that
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// doesn't exist in the body.
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Builder.CreateFlagStore(false, Coro.ResumeEHVar);
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CGF.ExitCXXTryStmt(*TryStmt);
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LValueOrRValue Res;
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// We are not supposed to obtain the value from init suspend await_resume().
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Res.RV = RValue::getIgnored();
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return Res;
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}
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LValueOrRValue Res;
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if (forLValue)
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Res.LV = CGF.EmitLValue(S.getResumeExpr());
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else
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Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
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return Res;
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}
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RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
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AggValueSlot aggSlot,
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bool ignoreResult) {
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return emitSuspendExpression(*this, *CurCoro.Data, E,
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CurCoro.Data->CurrentAwaitKind, aggSlot,
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ignoreResult, /*forLValue*/false).RV;
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}
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RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
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AggValueSlot aggSlot,
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bool ignoreResult) {
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return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
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aggSlot, ignoreResult, /*forLValue*/false).RV;
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}
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void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
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++CurCoro.Data->CoreturnCount;
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const Expr *RV = S.getOperand();
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if (RV && RV->getType()->isVoidType() && !isa<InitListExpr>(RV)) {
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// Make sure to evaluate the non initlist expression of a co_return
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// with a void expression for side effects.
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RunCleanupsScope cleanupScope(*this);
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EmitIgnoredExpr(RV);
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}
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EmitStmt(S.getPromiseCall());
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EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
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}
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#ifndef NDEBUG
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static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
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const CoroutineSuspendExpr *E) {
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const auto *RE = E->getResumeExpr();
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// Is it possible for RE to be a CXXBindTemporaryExpr wrapping
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// a MemberCallExpr?
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assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
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return cast<CallExpr>(RE)->getCallReturnType(Ctx);
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}
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#endif
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llvm::Function *
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CodeGenFunction::generateAwaitSuspendWrapper(Twine const &CoroName,
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Twine const &SuspendPointName,
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CoroutineSuspendExpr const &S) {
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std::string FuncName = "__await_suspend_wrapper_";
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FuncName += CoroName.str();
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FuncName += '_';
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FuncName += SuspendPointName.str();
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ASTContext &C = getContext();
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FunctionArgList args;
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ImplicitParamDecl AwaiterDecl(C, C.VoidPtrTy, ImplicitParamKind::Other);
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ImplicitParamDecl FrameDecl(C, C.VoidPtrTy, ImplicitParamKind::Other);
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QualType ReturnTy = S.getSuspendExpr()->getType();
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args.push_back(&AwaiterDecl);
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args.push_back(&FrameDecl);
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const CGFunctionInfo &FI =
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CGM.getTypes().arrangeBuiltinFunctionDeclaration(ReturnTy, args);
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llvm::FunctionType *LTy = CGM.getTypes().GetFunctionType(FI);
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llvm::Function *Fn = llvm::Function::Create(
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LTy, llvm::GlobalValue::PrivateLinkage, FuncName, &CGM.getModule());
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Fn->addParamAttr(0, llvm::Attribute::AttrKind::NonNull);
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Fn->addParamAttr(0, llvm::Attribute::AttrKind::NoUndef);
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Fn->addParamAttr(1, llvm::Attribute::AttrKind::NoUndef);
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Fn->setMustProgress();
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Fn->addFnAttr(llvm::Attribute::AttrKind::AlwaysInline);
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StartFunction(GlobalDecl(), ReturnTy, Fn, FI, args);
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// FIXME: add TBAA metadata to the loads
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llvm::Value *AwaiterPtr = Builder.CreateLoad(GetAddrOfLocalVar(&AwaiterDecl));
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auto AwaiterLValue =
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MakeNaturalAlignAddrLValue(AwaiterPtr, AwaiterDecl.getType());
|
||
|
||
CurAwaitSuspendWrapper.FramePtr =
|
||
Builder.CreateLoad(GetAddrOfLocalVar(&FrameDecl));
|
||
|
||
auto AwaiterBinder = CodeGenFunction::OpaqueValueMappingData::bind(
|
||
*this, S.getOpaqueValue(), AwaiterLValue);
|
||
|
||
auto *SuspendRet = EmitScalarExpr(S.getSuspendExpr());
|
||
|
||
auto UnbindCommonOnExit =
|
||
llvm::make_scope_exit([&] { AwaiterBinder.unbind(*this); });
|
||
if (SuspendRet != nullptr) {
|
||
Fn->addRetAttr(llvm::Attribute::AttrKind::NoUndef);
|
||
Builder.CreateStore(SuspendRet, ReturnValue);
|
||
}
|
||
|
||
CurAwaitSuspendWrapper.FramePtr = nullptr;
|
||
FinishFunction();
|
||
return Fn;
|
||
}
|
||
|
||
LValue
|
||
CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
|
||
assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
|
||
"Can't have a scalar return unless the return type is a "
|
||
"reference type!");
|
||
return emitSuspendExpression(*this, *CurCoro.Data, *E,
|
||
CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
|
||
/*ignoreResult*/false, /*forLValue*/true).LV;
|
||
}
|
||
|
||
LValue
|
||
CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
|
||
assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
|
||
"Can't have a scalar return unless the return type is a "
|
||
"reference type!");
|
||
return emitSuspendExpression(*this, *CurCoro.Data, *E,
|
||
AwaitKind::Yield, AggValueSlot::ignored(),
|
||
/*ignoreResult*/false, /*forLValue*/true).LV;
|
||
}
|
||
|
||
// Hunts for the parameter reference in the parameter copy/move declaration.
|
||
namespace {
|
||
struct GetParamRef : public StmtVisitor<GetParamRef> {
|
||
public:
|
||
DeclRefExpr *Expr = nullptr;
|
||
GetParamRef() {}
|
||
void VisitDeclRefExpr(DeclRefExpr *E) {
|
||
assert(Expr == nullptr && "multilple declref in param move");
|
||
Expr = E;
|
||
}
|
||
void VisitStmt(Stmt *S) {
|
||
for (auto *C : S->children()) {
|
||
if (C)
|
||
Visit(C);
|
||
}
|
||
}
|
||
};
|
||
}
|
||
|
||
// This class replaces references to parameters to their copies by changing
|
||
// the addresses in CGF.LocalDeclMap and restoring back the original values in
|
||
// its destructor.
|
||
|
||
namespace {
|
||
struct ParamReferenceReplacerRAII {
|
||
CodeGenFunction::DeclMapTy SavedLocals;
|
||
CodeGenFunction::DeclMapTy& LocalDeclMap;
|
||
|
||
ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
|
||
: LocalDeclMap(LocalDeclMap) {}
|
||
|
||
void addCopy(DeclStmt const *PM) {
|
||
// Figure out what param it refers to.
|
||
|
||
assert(PM->isSingleDecl());
|
||
VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
|
||
Expr const *InitExpr = VD->getInit();
|
||
GetParamRef Visitor;
|
||
Visitor.Visit(const_cast<Expr*>(InitExpr));
|
||
assert(Visitor.Expr);
|
||
DeclRefExpr *DREOrig = Visitor.Expr;
|
||
auto *PD = DREOrig->getDecl();
|
||
|
||
auto it = LocalDeclMap.find(PD);
|
||
assert(it != LocalDeclMap.end() && "parameter is not found");
|
||
SavedLocals.insert({ PD, it->second });
|
||
|
||
auto copyIt = LocalDeclMap.find(VD);
|
||
assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
|
||
it->second = copyIt->getSecond();
|
||
}
|
||
|
||
~ParamReferenceReplacerRAII() {
|
||
for (auto&& SavedLocal : SavedLocals) {
|
||
LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
|
||
}
|
||
}
|
||
};
|
||
}
|
||
|
||
// For WinEH exception representation backend needs to know what funclet coro.end
|
||
// belongs to. That information is passed in a funclet bundle.
|
||
static SmallVector<llvm::OperandBundleDef, 1>
|
||
getBundlesForCoroEnd(CodeGenFunction &CGF) {
|
||
SmallVector<llvm::OperandBundleDef, 1> BundleList;
|
||
|
||
if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
|
||
BundleList.emplace_back("funclet", EHPad);
|
||
|
||
return BundleList;
|
||
}
|
||
|
||
namespace {
|
||
// We will insert coro.end to cut any of the destructors for objects that
|
||
// do not need to be destroyed once the coroutine is resumed.
|
||
// See llvm/docs/Coroutines.rst for more details about coro.end.
|
||
struct CallCoroEnd final : public EHScopeStack::Cleanup {
|
||
void Emit(CodeGenFunction &CGF, Flags flags) override {
|
||
auto &CGM = CGF.CGM;
|
||
auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
|
||
llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
|
||
// See if we have a funclet bundle to associate coro.end with. (WinEH)
|
||
auto Bundles = getBundlesForCoroEnd(CGF);
|
||
auto *CoroEnd =
|
||
CGF.Builder.CreateCall(CoroEndFn,
|
||
{NullPtr, CGF.Builder.getTrue(),
|
||
llvm::ConstantTokenNone::get(CoroEndFn->getContext())},
|
||
Bundles);
|
||
if (Bundles.empty()) {
|
||
// Otherwise, (landingpad model), create a conditional branch that leads
|
||
// either to a cleanup block or a block with EH resume instruction.
|
||
auto *ResumeBB = CGF.getEHResumeBlock(/*isCleanup=*/true);
|
||
auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
|
||
CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
|
||
CGF.EmitBlock(CleanupContBB);
|
||
}
|
||
}
|
||
};
|
||
}
|
||
|
||
namespace {
|
||
// Make sure to call coro.delete on scope exit.
|
||
struct CallCoroDelete final : public EHScopeStack::Cleanup {
|
||
Stmt *Deallocate;
|
||
|
||
// Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
|
||
|
||
// Note: That deallocation will be emitted twice: once for a normal exit and
|
||
// once for exceptional exit. This usage is safe because Deallocate does not
|
||
// contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
|
||
// builds a single call to a deallocation function which is safe to emit
|
||
// multiple times.
|
||
void Emit(CodeGenFunction &CGF, Flags) override {
|
||
// Remember the current point, as we are going to emit deallocation code
|
||
// first to get to coro.free instruction that is an argument to a delete
|
||
// call.
|
||
BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
|
||
|
||
auto *FreeBB = CGF.createBasicBlock("coro.free");
|
||
CGF.EmitBlock(FreeBB);
|
||
CGF.EmitStmt(Deallocate);
|
||
|
||
auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
|
||
CGF.EmitBlock(AfterFreeBB);
|
||
|
||
// We should have captured coro.free from the emission of deallocate.
|
||
auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
|
||
if (!CoroFree) {
|
||
CGF.CGM.Error(Deallocate->getBeginLoc(),
|
||
"Deallocation expressoin does not refer to coro.free");
|
||
return;
|
||
}
|
||
|
||
// Get back to the block we were originally and move coro.free there.
|
||
auto *InsertPt = SaveInsertBlock->getTerminator();
|
||
CoroFree->moveBefore(InsertPt);
|
||
CGF.Builder.SetInsertPoint(InsertPt);
|
||
|
||
// Add if (auto *mem = coro.free) Deallocate;
|
||
auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
|
||
auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
|
||
CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
|
||
|
||
// No longer need old terminator.
|
||
InsertPt->eraseFromParent();
|
||
CGF.Builder.SetInsertPoint(AfterFreeBB);
|
||
}
|
||
explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
|
||
};
|
||
}
|
||
|
||
namespace {
|
||
struct GetReturnObjectManager {
|
||
CodeGenFunction &CGF;
|
||
CGBuilderTy &Builder;
|
||
const CoroutineBodyStmt &S;
|
||
// When true, performs RVO for the return object.
|
||
bool DirectEmit = false;
|
||
|
||
Address GroActiveFlag;
|
||
CodeGenFunction::AutoVarEmission GroEmission;
|
||
|
||
GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
|
||
: CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
|
||
GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {
|
||
// The call to get_return_object is sequenced before the call to
|
||
// initial_suspend and is invoked at most once, but there are caveats
|
||
// regarding on whether the prvalue result object may be initialized
|
||
// directly/eager or delayed, depending on the types involved.
|
||
//
|
||
// More info at https://github.com/cplusplus/papers/issues/1414
|
||
//
|
||
// The general cases:
|
||
// 1. Same type of get_return_object and coroutine return type (direct
|
||
// emission):
|
||
// - Constructed in the return slot.
|
||
// 2. Different types (delayed emission):
|
||
// - Constructed temporary object prior to initial suspend initialized with
|
||
// a call to get_return_object()
|
||
// - When coroutine needs to to return to the caller and needs to construct
|
||
// return value for the coroutine it is initialized with expiring value of
|
||
// the temporary obtained above.
|
||
//
|
||
// Direct emission for void returning coroutines or GROs.
|
||
DirectEmit = [&]() {
|
||
auto *RVI = S.getReturnValueInit();
|
||
assert(RVI && "expected RVI");
|
||
auto GroType = RVI->getType();
|
||
return CGF.getContext().hasSameType(GroType, CGF.FnRetTy);
|
||
}();
|
||
}
|
||
|
||
// The gro variable has to outlive coroutine frame and coroutine promise, but,
|
||
// it can only be initialized after coroutine promise was created, thus, we
|
||
// split its emission in two parts. EmitGroAlloca emits an alloca and sets up
|
||
// cleanups. Later when coroutine promise is available we initialize the gro
|
||
// and sets the flag that the cleanup is now active.
|
||
void EmitGroAlloca() {
|
||
if (DirectEmit)
|
||
return;
|
||
|
||
auto *GroDeclStmt = dyn_cast_or_null<DeclStmt>(S.getResultDecl());
|
||
if (!GroDeclStmt) {
|
||
// If get_return_object returns void, no need to do an alloca.
|
||
return;
|
||
}
|
||
|
||
auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
|
||
|
||
// Set GRO flag that it is not initialized yet
|
||
GroActiveFlag = CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(),
|
||
"gro.active");
|
||
Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
|
||
|
||
GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
|
||
auto *GroAlloca = dyn_cast_or_null<llvm::AllocaInst>(
|
||
GroEmission.getOriginalAllocatedAddress().getPointer());
|
||
assert(GroAlloca && "expected alloca to be emitted");
|
||
GroAlloca->setMetadata(llvm::LLVMContext::MD_coro_outside_frame,
|
||
llvm::MDNode::get(CGF.CGM.getLLVMContext(), {}));
|
||
|
||
// Remember the top of EHStack before emitting the cleanup.
|
||
auto old_top = CGF.EHStack.stable_begin();
|
||
CGF.EmitAutoVarCleanups(GroEmission);
|
||
auto top = CGF.EHStack.stable_begin();
|
||
|
||
// Make the cleanup conditional on gro.active
|
||
for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top); b != e;
|
||
b++) {
|
||
if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
|
||
assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
|
||
Cleanup->setActiveFlag(GroActiveFlag);
|
||
Cleanup->setTestFlagInEHCleanup();
|
||
Cleanup->setTestFlagInNormalCleanup();
|
||
}
|
||
}
|
||
}
|
||
|
||
void EmitGroInit() {
|
||
if (DirectEmit) {
|
||
// ReturnValue should be valid as long as the coroutine's return type
|
||
// is not void. The assertion could help us to reduce the check later.
|
||
assert(CGF.ReturnValue.isValid() == (bool)S.getReturnStmt());
|
||
// Now we have the promise, initialize the GRO.
|
||
// We need to emit `get_return_object` first. According to:
|
||
// [dcl.fct.def.coroutine]p7
|
||
// The call to get_return_object is sequenced before the call to
|
||
// initial_suspend and is invoked at most once.
|
||
//
|
||
// So we couldn't emit return value when we emit return statment,
|
||
// otherwise the call to get_return_object wouldn't be in front
|
||
// of initial_suspend.
|
||
if (CGF.ReturnValue.isValid()) {
|
||
CGF.EmitAnyExprToMem(S.getReturnValue(), CGF.ReturnValue,
|
||
S.getReturnValue()->getType().getQualifiers(),
|
||
/*IsInit*/ true);
|
||
}
|
||
return;
|
||
}
|
||
|
||
if (!GroActiveFlag.isValid()) {
|
||
// No Gro variable was allocated. Simply emit the call to
|
||
// get_return_object.
|
||
CGF.EmitStmt(S.getResultDecl());
|
||
return;
|
||
}
|
||
|
||
CGF.EmitAutoVarInit(GroEmission);
|
||
Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
|
||
}
|
||
};
|
||
} // namespace
|
||
|
||
static void emitBodyAndFallthrough(CodeGenFunction &CGF,
|
||
const CoroutineBodyStmt &S, Stmt *Body) {
|
||
CGF.EmitStmt(Body);
|
||
const bool CanFallthrough = CGF.Builder.GetInsertBlock();
|
||
if (CanFallthrough)
|
||
if (Stmt *OnFallthrough = S.getFallthroughHandler())
|
||
CGF.EmitStmt(OnFallthrough);
|
||
}
|
||
|
||
void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
|
||
auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getPtrTy());
|
||
auto &TI = CGM.getContext().getTargetInfo();
|
||
unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
|
||
|
||
auto *EntryBB = Builder.GetInsertBlock();
|
||
auto *AllocBB = createBasicBlock("coro.alloc");
|
||
auto *InitBB = createBasicBlock("coro.init");
|
||
auto *FinalBB = createBasicBlock("coro.final");
|
||
auto *RetBB = createBasicBlock("coro.ret");
|
||
|
||
auto *CoroId = Builder.CreateCall(
|
||
CGM.getIntrinsic(llvm::Intrinsic::coro_id),
|
||
{Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
|
||
createCoroData(*this, CurCoro, CoroId);
|
||
CurCoro.Data->SuspendBB = RetBB;
|
||
assert(ShouldEmitLifetimeMarkers &&
|
||
"Must emit lifetime intrinsics for coroutines");
|
||
|
||
// Backend is allowed to elide memory allocations, to help it, emit
|
||
// auto mem = coro.alloc() ? 0 : ... allocation code ...;
|
||
auto *CoroAlloc = Builder.CreateCall(
|
||
CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
|
||
|
||
Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
|
||
|
||
EmitBlock(AllocBB);
|
||
auto *AllocateCall = EmitScalarExpr(S.getAllocate());
|
||
auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
|
||
|
||
// Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
|
||
if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
|
||
auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
|
||
|
||
// See if allocation was successful.
|
||
auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
|
||
auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
|
||
// Expect the allocation to be successful.
|
||
emitCondLikelihoodViaExpectIntrinsic(Cond, Stmt::LH_Likely);
|
||
Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
|
||
|
||
// If not, return OnAllocFailure object.
|
||
EmitBlock(RetOnFailureBB);
|
||
EmitStmt(RetOnAllocFailure);
|
||
}
|
||
else {
|
||
Builder.CreateBr(InitBB);
|
||
}
|
||
|
||
EmitBlock(InitBB);
|
||
|
||
// Pass the result of the allocation to coro.begin.
|
||
auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
|
||
Phi->addIncoming(NullPtr, EntryBB);
|
||
Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
|
||
auto *CoroBegin = Builder.CreateCall(
|
||
CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
|
||
CurCoro.Data->CoroBegin = CoroBegin;
|
||
|
||
GetReturnObjectManager GroManager(*this, S);
|
||
GroManager.EmitGroAlloca();
|
||
|
||
CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
|
||
{
|
||
CGDebugInfo *DI = getDebugInfo();
|
||
ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
|
||
CodeGenFunction::RunCleanupsScope ResumeScope(*this);
|
||
EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
|
||
|
||
// Create mapping between parameters and copy-params for coroutine function.
|
||
llvm::ArrayRef<const Stmt *> ParamMoves = S.getParamMoves();
|
||
assert(
|
||
(ParamMoves.size() == 0 || (ParamMoves.size() == FnArgs.size())) &&
|
||
"ParamMoves and FnArgs should be the same size for coroutine function");
|
||
if (ParamMoves.size() == FnArgs.size() && DI)
|
||
for (const auto Pair : llvm::zip(FnArgs, ParamMoves))
|
||
DI->getCoroutineParameterMappings().insert(
|
||
{std::get<0>(Pair), std::get<1>(Pair)});
|
||
|
||
// Create parameter copies. We do it before creating a promise, since an
|
||
// evolution of coroutine TS may allow promise constructor to observe
|
||
// parameter copies.
|
||
for (auto *PM : S.getParamMoves()) {
|
||
EmitStmt(PM);
|
||
ParamReplacer.addCopy(cast<DeclStmt>(PM));
|
||
// TODO: if(CoroParam(...)) need to surround ctor and dtor
|
||
// for the copy, so that llvm can elide it if the copy is
|
||
// not needed.
|
||
}
|
||
|
||
EmitStmt(S.getPromiseDeclStmt());
|
||
|
||
Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
|
||
auto *PromiseAddrVoidPtr =
|
||
new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
|
||
// Update CoroId to refer to the promise. We could not do it earlier because
|
||
// promise local variable was not emitted yet.
|
||
CoroId->setArgOperand(1, PromiseAddrVoidPtr);
|
||
|
||
// Now we have the promise, initialize the GRO
|
||
GroManager.EmitGroInit();
|
||
|
||
EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
|
||
|
||
CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
|
||
CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
|
||
EmitStmt(S.getInitSuspendStmt());
|
||
CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
|
||
|
||
CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
|
||
|
||
if (CurCoro.Data->ExceptionHandler) {
|
||
// If we generated IR to record whether an exception was thrown from
|
||
// 'await_resume', then use that IR to determine whether the coroutine
|
||
// body should be skipped.
|
||
// If we didn't generate the IR (perhaps because 'await_resume' was marked
|
||
// as 'noexcept'), then we skip this check.
|
||
BasicBlock *ContBB = nullptr;
|
||
if (CurCoro.Data->ResumeEHVar) {
|
||
BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
|
||
ContBB = createBasicBlock("coro.resumed.cont");
|
||
Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
|
||
"coro.resumed.eh");
|
||
Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
|
||
EmitBlock(BodyBB);
|
||
}
|
||
|
||
auto Loc = S.getBeginLoc();
|
||
CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
|
||
CurCoro.Data->ExceptionHandler);
|
||
auto *TryStmt =
|
||
CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
|
||
|
||
EnterCXXTryStmt(*TryStmt);
|
||
emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
|
||
ExitCXXTryStmt(*TryStmt);
|
||
|
||
if (ContBB)
|
||
EmitBlock(ContBB);
|
||
}
|
||
else {
|
||
emitBodyAndFallthrough(*this, S, S.getBody());
|
||
}
|
||
|
||
// See if we need to generate final suspend.
|
||
const bool CanFallthrough = Builder.GetInsertBlock();
|
||
const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
|
||
if (CanFallthrough || HasCoreturns) {
|
||
EmitBlock(FinalBB);
|
||
CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
|
||
EmitStmt(S.getFinalSuspendStmt());
|
||
} else {
|
||
// We don't need FinalBB. Emit it to make sure the block is deleted.
|
||
EmitBlock(FinalBB, /*IsFinished=*/true);
|
||
}
|
||
}
|
||
|
||
EmitBlock(RetBB);
|
||
// Emit coro.end before getReturnStmt (and parameter destructors), since
|
||
// resume and destroy parts of the coroutine should not include them.
|
||
llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
|
||
Builder.CreateCall(CoroEnd,
|
||
{NullPtr, Builder.getFalse(),
|
||
llvm::ConstantTokenNone::get(CoroEnd->getContext())});
|
||
|
||
if (Stmt *Ret = S.getReturnStmt()) {
|
||
// Since we already emitted the return value above, so we shouldn't
|
||
// emit it again here.
|
||
if (GroManager.DirectEmit)
|
||
cast<ReturnStmt>(Ret)->setRetValue(nullptr);
|
||
EmitStmt(Ret);
|
||
}
|
||
|
||
// LLVM require the frontend to mark the coroutine.
|
||
CurFn->setPresplitCoroutine();
|
||
|
||
if (CXXRecordDecl *RD = FnRetTy->getAsCXXRecordDecl();
|
||
RD && RD->hasAttr<CoroOnlyDestroyWhenCompleteAttr>())
|
||
CurFn->setCoroDestroyOnlyWhenComplete();
|
||
}
|
||
|
||
// Emit coroutine intrinsic and patch up arguments of the token type.
|
||
RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
|
||
unsigned int IID) {
|
||
SmallVector<llvm::Value *, 8> Args;
|
||
switch (IID) {
|
||
default:
|
||
break;
|
||
// The coro.frame builtin is replaced with an SSA value of the coro.begin
|
||
// intrinsic.
|
||
case llvm::Intrinsic::coro_frame: {
|
||
if (CurCoro.Data && CurCoro.Data->CoroBegin) {
|
||
return RValue::get(CurCoro.Data->CoroBegin);
|
||
}
|
||
|
||
if (CurAwaitSuspendWrapper.FramePtr) {
|
||
return RValue::get(CurAwaitSuspendWrapper.FramePtr);
|
||
}
|
||
|
||
CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
|
||
"has been used earlier in this function");
|
||
auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getPtrTy());
|
||
return RValue::get(NullPtr);
|
||
}
|
||
case llvm::Intrinsic::coro_size: {
|
||
auto &Context = getContext();
|
||
CanQualType SizeTy = Context.getSizeType();
|
||
llvm::IntegerType *T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
|
||
llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::coro_size, T);
|
||
return RValue::get(Builder.CreateCall(F));
|
||
}
|
||
case llvm::Intrinsic::coro_align: {
|
||
auto &Context = getContext();
|
||
CanQualType SizeTy = Context.getSizeType();
|
||
llvm::IntegerType *T = Builder.getIntNTy(Context.getTypeSize(SizeTy));
|
||
llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::coro_align, T);
|
||
return RValue::get(Builder.CreateCall(F));
|
||
}
|
||
// The following three intrinsics take a token parameter referring to a token
|
||
// returned by earlier call to @llvm.coro.id. Since we cannot represent it in
|
||
// builtins, we patch it up here.
|
||
case llvm::Intrinsic::coro_alloc:
|
||
case llvm::Intrinsic::coro_begin:
|
||
case llvm::Intrinsic::coro_free: {
|
||
if (CurCoro.Data && CurCoro.Data->CoroId) {
|
||
Args.push_back(CurCoro.Data->CoroId);
|
||
break;
|
||
}
|
||
CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
|
||
" been used earlier in this function");
|
||
// Fallthrough to the next case to add TokenNone as the first argument.
|
||
[[fallthrough]];
|
||
}
|
||
// @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
|
||
// argument.
|
||
case llvm::Intrinsic::coro_suspend:
|
||
Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
|
||
break;
|
||
}
|
||
for (const Expr *Arg : E->arguments())
|
||
Args.push_back(EmitScalarExpr(Arg));
|
||
// @llvm.coro.end takes a token parameter. Add token 'none' as the last
|
||
// argument.
|
||
if (IID == llvm::Intrinsic::coro_end)
|
||
Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
|
||
|
||
llvm::Function *F = CGM.getIntrinsic(IID);
|
||
llvm::CallInst *Call = Builder.CreateCall(F, Args);
|
||
|
||
// Note: The following code is to enable to emit coro.id and coro.begin by
|
||
// hand to experiment with coroutines in C.
|
||
// If we see @llvm.coro.id remember it in the CoroData. We will update
|
||
// coro.alloc, coro.begin and coro.free intrinsics to refer to it.
|
||
if (IID == llvm::Intrinsic::coro_id) {
|
||
createCoroData(*this, CurCoro, Call, E);
|
||
}
|
||
else if (IID == llvm::Intrinsic::coro_begin) {
|
||
if (CurCoro.Data)
|
||
CurCoro.Data->CoroBegin = Call;
|
||
}
|
||
else if (IID == llvm::Intrinsic::coro_free) {
|
||
// Remember the last coro_free as we need it to build the conditional
|
||
// deletion of the coroutine frame.
|
||
if (CurCoro.Data)
|
||
CurCoro.Data->LastCoroFree = Call;
|
||
}
|
||
return RValue::get(Call);
|
||
}
|