r325081 - Implement function attribute artificial

Tue Feb 13 17:38:40 PST 2018

On 13 February 2018 at 16:14, Erich Keane via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: erichkeane
> Date: Tue Feb 13 16:14:07 2018
> New Revision: 325081
>
> URL: http://llvm.org/viewvc/llvm-project?rev=325081&view=rev
> Log:
> Implement function attribute artificial
>
> Added support in clang for GCC function attribute 'artificial'. This
> attribute
> is used to control stepping behavior of debugger with respect to inline
> functions.
>
> Patch By: Elizabeth Andrews (eandrews)
>
> Differential Revision: https://reviews.llvm.org/D43259
>
>
> Added:
>     cfe/trunk/test/CodeGen/artificial.c
>     cfe/trunk/test/Sema/artificial.c
> Modified:
>     cfe/trunk/include/clang/Basic/Attr.td
>     cfe/trunk/include/clang/Basic/AttrDocs.td
>     cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
>     cfe/trunk/lib/Sema/SemaDeclAttr.cpp
>
> Modified: cfe/trunk/include/clang/Basic/Attr.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/
> clang/Basic/Attr.td?rev=325081&r1=325080&r2=325081&view=diff
> ============================================================
> ==================
> --- cfe/trunk/include/clang/Basic/Attr.td (original)
> +++ cfe/trunk/include/clang/Basic/Attr.td Tue Feb 13 16:14:07 2018
> @@ -111,6 +111,9 @@ def SharedVar : SubsetSubject<Var,
>  def GlobalVar : SubsetSubject<Var,
>                               [{S->hasGlobalStorage()}], "global
> variables">;
>
> +def InlineFunction : SubsetSubject<Function,
> +                             [{S->isInlineSpecified()}], "inline
> functions">;
> +
>  // FIXME: this hack is needed because DeclNodes.td defines the base Decl
> node
>  // type to be a class, not a definition. This makes it impossible to
> create an
>  // attribute subject which accepts a Decl. Normally, this is not a
> problem,
> @@ -588,6 +591,12 @@ def AlwaysInline : InheritableAttr {
>    let Documentation = [Undocumented];
>  }
>
> +def Artificial : InheritableAttr {
> +  let Spellings = [GCC<"artificial">];
> +  let Subjects = SubjectList<[InlineFunction], WarnDiag>;
> +  let Documentation = [ArtificialDocs];
> +}
> +
>  def XRayInstrument : InheritableAttr {
>    let Spellings = [Clang<"xray_always_instrument">,
>                     Clang<"xray_never_instrument">];
>
> Modified: cfe/trunk/include/clang/Basic/AttrDocs.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/
> clang/Basic/AttrDocs.td?rev=325081&r1=325080&r2=325081&view=diff
> ============================================================
> ==================
> --- cfe/trunk/include/clang/Basic/AttrDocs.td (original)
> +++ cfe/trunk/include/clang/Basic/AttrDocs.td Tue Feb 13 16:14:07 2018
> @@ -3273,3 +3273,13 @@ For more information see
>  or `msvc documentation <https://docs.microsoft.com/
> pl-pl/cpp/cpp/selectany>`_.
>  }];
>  }
> +
> +def ArtificialDocs : Documentation {
> +  let Category = DocCatFunction;
> +  let Content = [{
> +The ``artificial`` attribute is used with inline functions to treat the
> inline
> +function as a unit while debugging. For more information see GCC_
> documentation.
>

I find this to be hard to understand. What does "treat the inline function
as a unit" actually mean? How about something like:

The ``artificial`` attribute can be applied to an inline function. If such
a function is inlined, the attribute indicates that debuggers should
associate the resulting instructions with the call site, rather than with
the corresponding line within the inlined callee.

+
> +.. _GCC: https://gcc.gnu.org/onlinedocs/gcc-4.6.4/gcc/
> Function-Attributes.html

If you still want to reference the GCC documentation, could you pick a
newer version? :)

+  }];
> +}
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/
> CGDebugInfo.cpp?rev=325081&r1=325080&r2=325081&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Tue Feb 13 16:14:07 2018
> @@ -3235,7 +3235,7 @@ void CGDebugInfo::EmitFunctionStart(Glob
>    if (Name.startswith("\01"))
>      Name = Name.substr(1);
>
> -  if (!HasDecl || D->isImplicit()) {
> +  if (!HasDecl || D->isImplicit() || D->hasAttr<ArtificialAttr>()) {
>      Flags |= llvm::DINode::FlagArtificial;
>      // Artificial functions should not silently reuse CurLoc.
>      CurLoc = SourceLocation();
>
> Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/
> SemaDeclAttr.cpp?rev=325081&r1=325080&r2=325081&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Tue Feb 13 16:14:07 2018
> @@ -6057,6 +6057,9 @@ static void ProcessDeclAttribute(Sema &S
>    case AttributeList::AT_AlwaysInline:
>      handleAlwaysInlineAttr(S, D, Attr);
>      break;
> +  case AttributeList::AT_Artificial:
> +    handleSimpleAttribute<ArtificialAttr>(S, D, Attr);
> +    break;
>    case AttributeList::AT_AnalyzerNoReturn:
>      handleAnalyzerNoReturnAttr(S, D, Attr);
>      break;
>
> Added: cfe/trunk/test/CodeGen/artificial.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/
> CodeGen/artificial.c?rev=325081&view=auto
> ============================================================
> ==================
> --- cfe/trunk/test/CodeGen/artificial.c (added)
> +++ cfe/trunk/test/CodeGen/artificial.c Tue Feb 13 16:14:07 2018
> @@ -0,0 +1,10 @@
> +// RUN: %clang_cc1 -triple=x86_64-unknown-linux-gnu -emit-llvm
> -debug-info-kind=limited %s -o - | FileCheck %s
> +
> +extern void foo();
> +// CHECK: !DISubprogram(name: "foo"
> +// CHECK-SAME: flags: DIFlagArtificial
> +inline void __attribute__((artificial)) foo() {}
> +
> +void baz() {
> +  foo();
> +}
>
> Added: cfe/trunk/test/Sema/artificial.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/
> artificial.c?rev=325081&view=auto
> ============================================================
> ==================
> --- cfe/trunk/test/Sema/artificial.c (added)
> +++ cfe/trunk/test/Sema/artificial.c Tue Feb 13 16:14:07 2018
> @@ -0,0 +1,4 @@
> +// RUN: %clang_cc1 -fsyntax-only -verify %s
> +
> +inline void __attribute__((artificial)) foo() {}
> +void __attribute__((artificial)) bar() {} // expected-warning
> {{'artificial' attribute only applies to inline functions}}
>
>
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