llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-debuginfo Author: Jeremy Morse (jmorse) <details> <summary>Changes</summary> At this time (immediately prior to llvm21 branching) we haven't instrumented coroutine generation to identify the "key" instructions of things like co_return and similar. This will lead to worse stepping behaviours, as there won't be any key instruction for those lines. This patch removes the key-instructions flag from the DISubprograms for coroutines, which will cause AsmPrinter to use the "old" / existing linetable stepping behaviour, avoiding a regression until we can instrument these constructs. (I'm going to post on discourse about whether this is a good idea or not in a moment) --- Full diff: https://github.com/llvm/llvm-project/pull/147551.diff 2 Files Affected: - (modified) clang/lib/CodeGen/CGDebugInfo.cpp (+5-1) - (added) clang/test/DebugInfo/KeyInstructions/coro-dwarf-key-instrs.cpp (+81) ``````````diff diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp index 8bf7d24d8551d..5240853199c11 100644 --- a/clang/lib/CodeGen/CGDebugInfo.cpp +++ b/clang/lib/CodeGen/CGDebugInfo.cpp @@ -4629,6 +4629,7 @@ void CGDebugInfo::emitFunctionStart(GlobalDecl GD, SourceLocation Loc, llvm::DIFile *Unit = getOrCreateFile(Loc); llvm::DIScope *FDContext = Unit; llvm::DINodeArray TParamsArray; + bool KeyInstructions = CGM.getCodeGenOpts().DebugKeyInstructions; if (!HasDecl) { // Use llvm function name. LinkageName = Fn->getName(); @@ -4645,6 +4646,9 @@ void CGDebugInfo::emitFunctionStart(GlobalDecl GD, SourceLocation Loc, } collectFunctionDeclProps(GD, Unit, Name, LinkageName, FDContext, TParamsArray, Flags); + // Disable KIs if this is a coroutine. + KeyInstructions = + KeyInstructions && !isa_and_present<CoroutineBodyStmt>(FD->getBody()); } else if (const auto *OMD = dyn_cast<ObjCMethodDecl>(D)) { Name = getObjCMethodName(OMD); Flags |= llvm::DINode::FlagPrototyped; @@ -4706,7 +4710,7 @@ void CGDebugInfo::emitFunctionStart(GlobalDecl GD, SourceLocation Loc, llvm::DISubprogram *SP = DBuilder.createFunction( FDContext, Name, LinkageName, Unit, LineNo, DIFnType, ScopeLine, FlagsForDef, SPFlagsForDef, TParamsArray.get(), Decl, nullptr, - Annotations, "", CGM.getCodeGenOpts().DebugKeyInstructions); + Annotations, "", KeyInstructions); Fn->setSubprogram(SP); // We might get here with a VarDecl in the case we're generating diff --git a/clang/test/DebugInfo/KeyInstructions/coro-dwarf-key-instrs.cpp b/clang/test/DebugInfo/KeyInstructions/coro-dwarf-key-instrs.cpp new file mode 100644 index 0000000000000..66537db88155d --- /dev/null +++ b/clang/test/DebugInfo/KeyInstructions/coro-dwarf-key-instrs.cpp @@ -0,0 +1,81 @@ +// RUN: %clang_cc1 -disable-llvm-optzns -std=c++20 \ +// RUN: -triple=x86_64 -dwarf-version=4 -debug-info-kind=limited \ +// RUN: -emit-llvm -o - %s -gkey-instructions | \ +// RUN: FileCheck %s + +// Check that for the coroutine below, we mark the created DISubprogram as +// not having key instructions. This will prevent AsmPrinter from trying to +// instrument the linetable with key-instructions for source-locations in +// the coroutine scope. +// +// This is a temporary workaround for key instructions: we can instrument +// coroutine code in the future, but it hasn't been done yet. +// +// File contents copied from coro-dwarf.cpp. + +namespace std { +template <typename... T> struct coroutine_traits; + +template <class Promise = void> struct coroutine_handle { + coroutine_handle() = default; + static coroutine_handle from_address(void *) noexcept; +}; +template <> struct coroutine_handle<void> { + static coroutine_handle from_address(void *) noexcept; + coroutine_handle() = default; + template <class PromiseType> + coroutine_handle(coroutine_handle<PromiseType>) noexcept; +}; +} // namespace std + +struct suspend_always { + bool await_ready() noexcept; + void await_suspend(std::coroutine_handle<>) noexcept; + void await_resume() noexcept; +}; + +template <typename... Args> struct std::coroutine_traits<void, Args...> { + struct promise_type { + void get_return_object() noexcept; + suspend_always initial_suspend() noexcept; + suspend_always final_suspend() noexcept; + void return_void() noexcept; + promise_type(); + ~promise_type() noexcept; + void unhandled_exception() noexcept; + }; +}; + +// TODO: Not supported yet +struct CopyOnly { + int val; + CopyOnly(const CopyOnly &) noexcept; + CopyOnly(CopyOnly &&) = delete; + ~CopyOnly(); +}; + +struct MoveOnly { + int val; + MoveOnly(const MoveOnly &) = delete; + MoveOnly(MoveOnly &&) noexcept; + ~MoveOnly(); +}; + +struct MoveAndCopy { + int val; + MoveAndCopy(const MoveAndCopy &) noexcept; + MoveAndCopy(MoveAndCopy &&) noexcept; + ~MoveAndCopy(); +}; + +void consume(int, int, int) noexcept; + +void f_coro(int val, MoveOnly moParam, MoveAndCopy mcParam) { + consume(val, moParam.val, mcParam.val); + co_return; +} + +// CHECK: ![[SP:[0-9]+]] = distinct !DISubprogram(name: "f_coro", linkageName: "_Z6f_coroi8MoveOnly11MoveAndCopy" +// CHECK-NOT: keyInstructions: +// CHECK: !DIFil + `````````` </details> https://github.com/llvm/llvm-project/pull/147551 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
