https://github.com/mmha created https://github.com/llvm/llvm-project/pull/231050
The initial await_resume() result may have a throwing destructor. Destroy it inside the resumption try/catch before marking resumption successful, so a destructor exception calls unhandled_exception() and skips the coroutine body. >From 7bfa85a19bed2ff34583957013da0b647ea9d8b3 Mon Sep 17 00:00:00 2001 From: Morris Hafner <[email protected]> Date: Sun, 11 Oct 2026 23:50:26 +0000 Subject: [PATCH] [CIR] Handle throwing destructors of initial await_resume results The initial await_resume() result may have a throwing destructor. Destroy it inside the resumption try/catch before marking resumption successful, so a destructor exception calls unhandled_exception() and skips the coroutine body. Co-Authored-By: Claude Opus 5.5 <[email protected]> --- clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp | 46 ++++-- clang/test/CIR/CodeGenCoroutines/coro-agg.cpp | 144 +++++++++++++++++- 2 files changed, 172 insertions(+), 18 deletions(-) diff --git a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp index ad34df762fe19..7e0f61121595a 100644 --- a/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp +++ b/clang/lib/CIR/CodeGen/CIRGenCoroutine.cpp @@ -634,14 +634,29 @@ CIRGenFunction::emitCoroutineBody(const CoroutineBodyStmt &s) { return res; } -static bool memberCallExpressionCanThrow(const Expr *e) { - if (const auto *ce = dyn_cast<CXXMemberCallExpr>(e)) - if (const auto *proto = - ce->getMethodDecl()->getType()->getAs<FunctionProtoType>()) - if (isNoexceptExceptionSpec(proto->getExceptionSpecType()) && - proto->canThrow() == CT_Cannot) - return false; - return true; +static bool functionCanThrow(const FunctionDecl *d) { + const auto *proto = d->getType()->getAs<FunctionProtoType>(); + if (!proto) + return true; + return !isNoexceptExceptionSpec(proto->getExceptionSpecType()) || + proto->canThrow() != CT_Cannot; +} + +static bool stmtCanThrow(const Stmt *s) { + if (const auto *ce = dyn_cast<CallExpr>(s)) { + const FunctionDecl *callee = ce->getDirectCallee(); + if (!callee || functionCanThrow(callee)) + return true; + } + + // The destructor call of a bound temporary is not among the children. + if (const auto *te = dyn_cast<CXXBindTemporaryExpr>(s)) + if (functionCanThrow(te->getTemporary()->getDestructor())) + return true; + + return llvm::any_of(s->children(), [](const Stmt *child) { + return child && stmtCanThrow(child); + }); } // Given a suspend expression which roughly looks like: @@ -667,6 +682,12 @@ struct LValueOrRValue { }; } // namespace +static bool isResumeExprInTryCatch(const CGCoroData &coro, cir::AwaitKind kind, + const CoroutineSuspendExpr &s) { + return coro.exceptionHandler && kind == cir::AwaitKind::Init && + stmtCanThrow(s.getResumeExpr()); +} + static LValueOrRValue emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro, CoroutineSuspendExpr const &s, cir::AwaitKind kind, @@ -681,10 +702,9 @@ emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro, CIRGenBuilderTy &builder = cgf.getBuilder(); // Exception handling requires additional IR. We avoid generating it when - // the resume expression is a direct call to a 'noexcept' member function. - const bool resumeInTry = coro.exceptionHandler && - kind == cir::AwaitKind::Init && - memberCallExpressionCanThrow(s.getResumeExpr()); + // neither the await_resume() call nor the destruction of its result can + // throw. + const bool resumeInTry = isResumeExprInTryCatch(coro, kind, s); // If the await_resume() result needs a destructor, take over its // destruction, unless the destination owns it. The try/catch path destroys @@ -768,8 +788,10 @@ emitSuspendExpression(CIRGenFunction &cgf, CGCoroData &coro, resumeEHVar(resumeEHVar.getPointer()) {} mlir::LogicalResult operator()(CIRGenFunction &cgf) override { + CIRGenFunction::RunCleanupsScope resumeCleanups(cgf); mlir::LogicalResult res = cgf.emitStmt(tryStmt.getTryBlock(), /*useCurrentScope=*/true); + resumeCleanups.forceCleanup(); cgf.getBuilder().createFlagStore(loc, true, resumeEHVar); return res; } diff --git a/clang/test/CIR/CodeGenCoroutines/coro-agg.cpp b/clang/test/CIR/CodeGenCoroutines/coro-agg.cpp index a966537abf918..83262823ed72a 100644 --- a/clang/test/CIR/CodeGenCoroutines/coro-agg.cpp +++ b/clang/test/CIR/CodeGenCoroutines/coro-agg.cpp @@ -1,9 +1,11 @@ // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -Wno-coroutine-missing-unhandled-exception -emit-cir %s -o %t.cir -// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR +// RUN: FileCheck --input-file=%t.cir %s -check-prefixes=CIR,CIR-COMMON,CIR-NOEH // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -fcxx-exceptions -fexceptions -Wno-coroutine-missing-unhandled-exception -emit-cir %s -o %t.eh.cir -// RUN: FileCheck --input-file=%t.eh.cir %s -check-prefix=CIR-EH +// RUN: FileCheck --input-file=%t.eh.cir %s -check-prefixes=CIR-EH,CIR-COMMON // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -emit-llvm -disable-llvm-passes -Wno-coroutine-missing-unhandled-exception %s -o %t.ll // RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG +// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fcxx-exceptions -fexceptions -emit-llvm -disable-llvm-passes -Wno-coroutine-missing-unhandled-exception %s -o %t.eh.ll +// RUN: FileCheck --input-file=%t.eh.ll %s -check-prefix=OGCG-EH #include "Inputs/coroutine.h" @@ -425,18 +427,25 @@ struct coro_init_final_nt_t { // CIR-NEXT: } cleanup normal { // CIR-NEXT: cir.call @_ZN2NTD1Ev(%[[FINAL]]) -// With exceptions, the initial await_resume() is emitted in a try/catch that -// owns and destroys the result; nothing is pushed after the cir.await. +// With exceptions, destroy the initial resume result in the try block before +// setting the flag that allows the body to run. // CIR-EH-LABEL: cir.func coroutine {{.*}} @_Z21init_final_nontrivialv +// CIR-EH: %[[RESUME_EH:.*]] = cir.alloca "resume.eh" // CIR-EH: cir.coroutine initialSuspend : { // CIR-EH: cir.await(init, ready : { // CIR-EH: }, resume : { // CIR-EH: cir.try { // CIR-EH-NEXT: cir.call @_ZN11InitAwaitNT12await_resumeEv(%[[INIT:.*]], %{{.*}}) // CIR-EH-NEXT: cir.cleanup.scope { -// CIR-EH: } cleanup all { +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } cleanup all { // CIR-EH-NEXT: cir.call @_ZN2NTD1Ev(%[[INIT]]) -// CIR-EH: } catch all +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } +// CIR-EH-NEXT: %[[TRUE:.*]] = cir.const #true +// CIR-EH-NEXT: cir.store %[[TRUE]], %[[RESUME_EH]] +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } catch all // CIR-EH: },) // CIR-EH-NEXT: cir.yield // CIR-EH-NEXT: }, body : { @@ -458,4 +467,127 @@ struct coro_init_final_nt_t { // OGCG: final.ready: // OGCG-NEXT: call void @_ZN12FinalAwaitNT12await_resumeEv(ptr {{.*}} %[[FINAL:.*]], ptr // OGCG-NEXT: call void @_ZN2NTD1Ev(ptr {{.*}} %[[FINAL]]) + +// OGCG-EH-LABEL: define {{.*}} void @_Z21init_final_nontrivialv( +// OGCG-EH: init.ready: +// OGCG-EH-NEXT: store i1 true, ptr %[[RESUME_EH:.*]], align 1 +// OGCG-EH-NEXT: invoke void @_ZN11InitAwaitNT12await_resumeEv(ptr {{.*}} %[[INIT:.*]], ptr +// OGCG-EH-NEXT: to label %[[CONT:.*]] unwind label +// OGCG-EH: [[CONT]]: +// OGCG-EH-NEXT: call void @_ZN2NTD1Ev(ptr {{.*}} %[[INIT]]) +// OGCG-EH-NEXT: store i1 false, ptr %[[RESUME_EH]], align 1 coro_init_final_nt_t init_final_nontrivial() { co_return; } + +void next(); + +// The try/catch is only needed if the resume expression can throw: here +// neither await_resume() nor the result's destructor can. + +struct NoexceptInitAw { + bool await_ready() noexcept; + void await_suspend(std::coroutine_handle<>) noexcept; + NT await_resume() noexcept; +}; + +struct NoexceptInitTask { + struct promise_type { + NoexceptInitTask get_return_object() noexcept; + NoexceptInitAw initial_suspend() noexcept; + std::suspend_never final_suspend() noexcept; + void return_void() noexcept; + void unhandled_exception() noexcept; + }; +}; + +NoexceptInitTask noexcept_initial_resume() { + next(); + co_return; +} + +// CIR-COMMON-LABEL: cir.func coroutine {{.*}} @_Z23noexcept_initial_resumev( +// CIR-COMMON-NOT: resume.eh +// CIR-COMMON: %[[INIT:.*]] = cir.alloca "agg.tmp.ensured" align(4) : !cir.ptr<!rec_NT> +// CIR-COMMON-NOT: resume.eh +// CIR-COMMON: cir.await(init, ready : { +// CIR-COMMON: }, resume : { +// CIR-COMMON-NEXT: cir.call @_ZN14NoexceptInitAw12await_resumeEv(%[[INIT]], %{{.*}}) +// CIR-COMMON-NEXT: cir.yield +// CIR-COMMON-NEXT: },) +// CIR-COMMON-NEXT: cir.cleanup.scope { +// CIR-COMMON-NEXT: cir.yield +// CIR-NOEH-NEXT: } cleanup normal { +// CIR-EH-NEXT: } cleanup all { +// CIR-COMMON-NEXT: cir.call @_ZN2NTD1Ev(%[[INIT]]) +// CIR-COMMON-NEXT: cir.yield +// CIR-COMMON-NEXT: } +// CIR-COMMON-NEXT: cir.yield +// CIR-COMMON-NEXT: }, body : { +// CIR-COMMON-NOT: resume.eh +// CIR-COMMON: }, finalSuspend : { + +// OGCG-EH-LABEL: define {{.*}} void @_Z23noexcept_initial_resumev( +// OGCG-EH-NOT: initresume.eh +// OGCG-EH: init.ready: +// OGCG-EH-NEXT: call void @_ZN14NoexceptInitAw12await_resumeEv(ptr {{.*}} %[[INIT:.*]], ptr +// OGCG-EH-NEXT: call void @_ZN2NTD1Ev(ptr {{.*}} %[[INIT]]) +// OGCG-EH-NOT: initresume.eh +// OGCG-EH: define + +// With a destructor that may throw, a noexcept await_resume() call is still in +// the try/catch, and the result is destroyed before the flag is set. + +struct TD { + int x; + ~TD() noexcept(false); +}; + +struct ThrowingDtorInitAw { + bool await_ready() noexcept; + void await_suspend(std::coroutine_handle<>) noexcept; + TD await_resume() noexcept; +}; + +struct ThrowingDtorInitTask { + struct promise_type { + ThrowingDtorInitTask get_return_object() noexcept; + ThrowingDtorInitAw initial_suspend() noexcept; + std::suspend_never final_suspend() noexcept; + void return_void() noexcept; + void unhandled_exception() noexcept; + }; +}; + +ThrowingDtorInitTask throwing_dtor_initial_resume() { + next(); + co_return; +} + +// CIR-COMMON-LABEL: cir.func coroutine {{.*}} @_Z28throwing_dtor_initial_resumev( +// CIR-EH: %[[RESUME_EH:.*]] = cir.alloca "resume.eh" +// CIR-COMMON: cir.await(init, ready : { +// CIR-COMMON: }, resume : { +// CIR-EH: cir.try { +// CIR-EH-NEXT: cir.call @_ZN18ThrowingDtorInitAw12await_resumeEv(%[[INIT:.*]], %{{.*}}) +// CIR-EH-NEXT: cir.cleanup.scope { +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } cleanup all { +// CIR-EH-NEXT: cir.call @_ZN2TDD1Ev(%[[INIT]]) +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } +// CIR-EH-NEXT: %[[TRUE:.*]] = cir.const #true +// CIR-EH-NEXT: cir.store %[[TRUE]], %[[RESUME_EH]] +// CIR-EH-NEXT: cir.yield +// CIR-EH-NEXT: } catch all +// CIR-COMMON: }, body : { +// CIR-EH-NEXT: %[[RESUMED:.*]] = cir.load {{.*}} %[[RESUME_EH]] +// CIR-EH-NEXT: cir.if %[[RESUMED]] { +// CIR-EH: cir.call @_Z4nextv() + +// OGCG-EH-LABEL: define {{.*}} void @_Z28throwing_dtor_initial_resumev( +// OGCG-EH: init.ready: +// OGCG-EH-NEXT: store i1 true, ptr %[[RESUME_EH:.*]], align 1 +// OGCG-EH-NEXT: call void @_ZN18ThrowingDtorInitAw12await_resumeEv(ptr {{.*}} %[[INIT:.*]], ptr +// OGCG-EH-NEXT: invoke void @_ZN2TDD1Ev(ptr {{.*}} %[[INIT]]) +// OGCG-EH-NEXT: to label %[[CONT:.*]] unwind label +// OGCG-EH: [[CONT]]: +// OGCG-EH-NEXT: store i1 false, ptr %[[RESUME_EH]], align 1 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
