https://github.com/Michael137 created https://github.com/llvm/llvm-project/pull/122897
We currently don't emit `DW_AT_object_pointer` on function declarations or definitions. GCC suffers from the same issue: https://godbolt.org/z/h4jeT54G5 If I interpreted the DWARFv5 spec correctly, it doesn't mandate this attribute be present *only* for implicit object parameters: ``` If the member function entry describes a non-static member function, then that entry has a DW_AT_object_pointer attribute whose value is a reference to the formal parameter entry that corresponds to the object for which the function is called. That parameter also has a DW_AT_artificial attribute whose value is true. ``` This patch attaches the `DW_AT_object_pointer` for function *defintions*. The declarations will be handled in a separate patch. The part about `DW_AT_artificial` seems overly restrictive, and not true for explicit object parameters. We probably should relax this part of the DWARF spec. This will help LLDB identify static vs. non-static member functions (see https://github.com/llvm/llvm-project/issues/120856). Partially fixes https://github.com/llvm/llvm-project/issues/120974 >From d221dd5ef2c54f63fb6966ca5de8e41c5a8dd6bf Mon Sep 17 00:00:00 2001 From: Michael Buch <michaelbuc...@gmail.com> Date: Tue, 14 Jan 2025 11:33:33 +0000 Subject: [PATCH] [clang][DebugInfo] Emit DW_AT_object_pointer on function definitions with explicit `this` We currently don't emit `DW_AT_object_pointer` on function declarations or definitions. The DWARFv5 spec doesn't mandate this attribute be present *only* for implicit object parameters: ``` If the member function entry describes a non-static member function, then that entry has a DW_AT_object_pointer attribute whose value is a reference to the formal parameter entry that corresponds to the object for which the function is called. That parameter also has a DW_AT_artificial attribute whose value is true. ``` The part about `DW_AT_artificial` seems overly restrictive, and not true for explicit object parameters. We probably should relax this part of the DWARF spec. This will help LLDB identify static vs. non-static member functions (see https://github.com/llvm/llvm-project/issues/120856). GCC suffers from the same issue: https://godbolt.org/z/h4jeT54G5 Partially fixes https://github.com/llvm/llvm-project/issues/120974 --- clang/lib/CodeGen/CGDebugInfo.cpp | 3 ++ .../CodeGenCXX/debug-info-object-pointer.cpp | 29 +++++++++++++++++++ 2 files changed, 32 insertions(+) create mode 100644 clang/test/CodeGenCXX/debug-info-object-pointer.cpp diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp index d7e5e95b7873a0..f9cba414dcfe2c 100644 --- a/clang/lib/CodeGen/CGDebugInfo.cpp +++ b/clang/lib/CodeGen/CGDebugInfo.cpp @@ -4829,6 +4829,9 @@ llvm::DILocalVariable *CGDebugInfo::EmitDeclare(const VarDecl *VD, if (IPD->getParameterKind() == ImplicitParamKind::CXXThis || IPD->getParameterKind() == ImplicitParamKind::ObjCSelf) Flags |= llvm::DINode::FlagObjectPointer; + } else if (const auto *PVD = dyn_cast<ParmVarDecl>(VD)) { + if (PVD->isExplicitObjectParameter()) + Flags |= llvm::DINode::FlagObjectPointer; } // Note: Older versions of clang used to emit byval references with an extra diff --git a/clang/test/CodeGenCXX/debug-info-object-pointer.cpp b/clang/test/CodeGenCXX/debug-info-object-pointer.cpp new file mode 100644 index 00000000000000..594d4da791ee84 --- /dev/null +++ b/clang/test/CodeGenCXX/debug-info-object-pointer.cpp @@ -0,0 +1,29 @@ +// RUN: %clang_cc1 -x c++ -std=c++23 -debug-info-kind=limited -emit-llvm < %s | FileCheck %s + +// CHECK: !DISubprogram(name: "bar", +// CHECK-SAME: flags: DIFlagPrototyped +// CHECK: !DIDerivedType(tag: DW_TAG_pointer_type +// CHECK-SAME: flags: DIFlagArtificial | DIFlagObjectPointer +// +// // FIXME: DIFlagObjectPointer not attached to the explicit object +// // argument in the subprogram declaration. +// CHECK: !DISubprogram(name: "explicit_this", +// flags: DIFlagPrototyped +// CHECK-NOT: DIFlagObjectPointer +// CHECK-NOT: DIFlagArtificial +// +// CHECK: !DILocalVariable(name: "this", arg: 1 +// CHECK-SAME: flags: DIFlagArtificial | DIFlagObjectPointer +// +// CHECK-NOT: DIFlagArtificial +// CHECK: !DILocalVariable(arg: 1, {{.*}}, flags: DIFlagObjectPointer) + +struct Foo { + void bar() {} + void explicit_this(this Foo &&) {} +}; + +void f() { + Foo{}.bar(); + Foo{}.explicit_this(); +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
