Oh, yeah - so the trick here is that you don't just drop the typedef, but you drop an context for that typedef (if it's not otherwise used) - like namespaces (probably otherwise used) and classes (in the class of C++ type traits these aren't generally referenced in ways other than the typedef they contain).
See http://lists.llvm.org/pipermail/libcxx-commits/2019-June/004697.html for some stats/usage. On Mon, Jun 17, 2019 at 11:00 AM <paul.robin...@sony.com> wrote: > Is this really measurable? All you're suppressing are the typedef DIEs > and their names; the DIEs are small, although I admit the names can take > up space. > (I'm not really objecting, it's just hard to intuit a big size benefit.) > --paulr > > > -----Original Message----- > > From: cfe-commits [mailto:cfe-commits-boun...@lists.llvm.org] On Behalf > Of > > David Blaikie via cfe-commits > > Sent: Friday, June 07, 2019 8:01 PM > > To: cfe-commits@lists.llvm.org > > Subject: r362856 - DebugInfo: Add support for 'nodebug' attribute on > > typedefs and alias templates > > > > Author: dblaikie > > Date: Fri Jun 7 17:01:21 2019 > > New Revision: 362856 > > > > URL: http://llvm.org/viewvc/llvm-project?rev=362856&view=rev > > Log: > > DebugInfo: Add support for 'nodebug' attribute on typedefs and alias > > templates > > > > Seems like a logical extension to me - and of interest because it might > > help reduce the debug info size of libc++ by applying this attribute to > > type traits that have a disproportionate debug info cost compared to the > > benefit (& possibly harm/confusion) they cause users. > > > > Modified: > > cfe/trunk/include/clang/Basic/Attr.td > > cfe/trunk/lib/CodeGen/CGDebugInfo.cpp > > cfe/trunk/test/CodeGenCXX/debug-info-nodebug.cpp > > cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test > > cfe/trunk/test/Sema/attr-nodebug.c > > > > Modified: cfe/trunk/include/clang/Basic/Attr.td > > URL: http://llvm.org/viewvc/llvm- > > > project/cfe/trunk/include/clang/Basic/Attr.td?rev=362856&r1=362855&r2=3628 > > 56&view=diff > > > ========================================================================== > > ==== > > --- cfe/trunk/include/clang/Basic/Attr.td (original) > > +++ cfe/trunk/include/clang/Basic/Attr.td Fri Jun 7 17:01:21 2019 > > @@ -1434,7 +1434,7 @@ def NoCommon : InheritableAttr { > > > > def NoDebug : InheritableAttr { > > let Spellings = [GCC<"nodebug">]; > > - let Subjects = SubjectList<[FunctionLike, ObjCMethod, NonParmVar]>; > > + let Subjects = SubjectList<[TypedefName, FunctionLike, ObjCMethod, > > NonParmVar]>; > > let Documentation = [NoDebugDocs]; > > } > > > > > > Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp > > URL: http://llvm.org/viewvc/llvm- > > > project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=362856&r1=362855&r2=3628 > > 56&view=diff > > > ========================================================================== > > ==== > > --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original) > > +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Fri Jun 7 17:01:21 2019 > > @@ -1091,15 +1091,18 @@ llvm::DIType *CGDebugInfo::CreateType(co > > assert(Ty->isTypeAlias()); > > llvm::DIType *Src = getOrCreateType(Ty->getAliasedType(), Unit); > > > > + auto *AliasDecl = > > + cast<TypeAliasTemplateDecl>(Ty- > > >getTemplateName().getAsTemplateDecl()) > > + ->getTemplatedDecl(); > > + > > + if (AliasDecl->hasAttr<NoDebugAttr>()) > > + return Src; > > + > > SmallString<128> NS; > > llvm::raw_svector_ostream OS(NS); > > Ty->getTemplateName().print(OS, getPrintingPolicy(), /*qualified*/ > > false); > > printTemplateArgumentList(OS, Ty->template_arguments(), > > getPrintingPolicy()); > > > > - auto *AliasDecl = > > - cast<TypeAliasTemplateDecl>(Ty- > > >getTemplateName().getAsTemplateDecl()) > > - ->getTemplatedDecl(); > > - > > SourceLocation Loc = AliasDecl->getLocation(); > > return DBuilder.createTypedef(Src, OS.str(), getOrCreateFile(Loc), > > getLineNumber(Loc), > > @@ -1108,15 +1111,20 @@ llvm::DIType *CGDebugInfo::CreateType(co > > > > llvm::DIType *CGDebugInfo::CreateType(const TypedefType *Ty, > > llvm::DIFile *Unit) { > > + llvm::DIType *Underlying = > > + getOrCreateType(Ty->getDecl()->getUnderlyingType(), Unit); > > + > > + if (Ty->getDecl()->hasAttr<NoDebugAttr>()) > > + return Underlying; > > + > > // We don't set size information, but do specify where the typedef was > > // declared. > > SourceLocation Loc = Ty->getDecl()->getLocation(); > > > > // Typedefs are derived from some other type. > > - return DBuilder.createTypedef( > > - getOrCreateType(Ty->getDecl()->getUnderlyingType(), Unit), > > - Ty->getDecl()->getName(), getOrCreateFile(Loc), > getLineNumber(Loc), > > - getDeclContextDescriptor(Ty->getDecl())); > > + return DBuilder.createTypedef(Underlying, Ty->getDecl()->getName(), > > + getOrCreateFile(Loc), > getLineNumber(Loc), > > + > getDeclContextDescriptor(Ty->getDecl())); > > } > > > > static unsigned getDwarfCC(CallingConv CC) { > > > > Modified: cfe/trunk/test/CodeGenCXX/debug-info-nodebug.cpp > > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug- > > info-nodebug.cpp?rev=362856&r1=362855&r2=362856&view=diff > > > ========================================================================== > > ==== > > --- cfe/trunk/test/CodeGenCXX/debug-info-nodebug.cpp (original) > > +++ cfe/trunk/test/CodeGenCXX/debug-info-nodebug.cpp Fri Jun 7 17:01:21 > > 2019 > > @@ -1,5 +1,5 @@ > > -// RUN: %clang_cc1 -DSETNODEBUG=0 -emit-llvm -debug-info-kind=limited %s > > -o - | FileCheck %s --check-prefix=YESINFO > > -// RUN: %clang_cc1 -DSETNODEBUG=1 -emit-llvm -debug-info-kind=limited %s > > -o - | FileCheck %s --check-prefix=NOINFO > > +// RUN: %clang_cc1 -DSETNODEBUG=0 -emit-llvm -std=c++14 -debug-info- > > kind=limited %s -o - | FileCheck %s --check-prefix=YESINFO > > +// RUN: %clang_cc1 -DSETNODEBUG=1 -emit-llvm -std=c++14 -debug-info- > > kind=limited %s -o - | FileCheck %s --check-prefix=NOINFO > > > > #if SETNODEBUG > > #define NODEBUG __attribute__((nodebug)) > > @@ -53,3 +53,15 @@ void func4() { > > // NOINFO-NOT: !DIGlobalVariable(name: "static_local" > > // YESINFO-DAG: !DILocalVariable(name: "normal_local" > > // NOINFO-NOT: !DILocalVariable(name: "normal_local" > > + > > +template <typename T> > > +using y NODEBUG = int; > > +void func5() { > > + NODEBUG typedef int x; > > + x a; > > + y<int> b; > > +} > > +// YESINFO-DAG: !DIDerivedType(tag: DW_TAG_typedef, name: "x" > > +// NOINFO-NOT: !DIDerivedType(tag: DW_TAG_typedef, name: "x" > > +// YESINFO-DAG: !DIDerivedType(tag: DW_TAG_typedef, name: "y<int>" > > +// NOINFO-NOT: !DIDerivedType(tag: DW_TAG_typedef, name: "y<int>" > > > > Modified: cfe/trunk/test/Misc/pragma-attribute-supported-attributes- > > list.test > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Misc/pragma- > > attribute-supported-attributes- > > list.test?rev=362856&r1=362855&r2=362856&view=diff > > > ========================================================================== > > ==== > > --- cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test > > (original) > > +++ cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test > > Fri Jun 7 17:01:21 2019 > > @@ -72,7 +72,7 @@ > > // CHECK-NEXT: NSConsumesSelf (SubjectMatchRule_objc_method) > > // CHECK-NEXT: Naked (SubjectMatchRule_function) > > // CHECK-NEXT: NoCommon (SubjectMatchRule_variable) > > -// CHECK-NEXT: NoDebug (SubjectMatchRule_hasType_functionType, > > SubjectMatchRule_objc_method, SubjectMatchRule_variable_not_is_parameter) > > +// CHECK-NEXT: NoDebug (SubjectMatchRule_type_alias, > > SubjectMatchRule_hasType_functionType, SubjectMatchRule_objc_method, > > SubjectMatchRule_variable_not_is_parameter) > > // CHECK-NEXT: NoDestroy (SubjectMatchRule_variable) > > // CHECK-NEXT: NoDuplicate (SubjectMatchRule_function) > > // CHECK-NEXT: NoEscape (SubjectMatchRule_variable_is_parameter) > > > > Modified: cfe/trunk/test/Sema/attr-nodebug.c > > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/attr- > > nodebug.c?rev=362856&r1=362855&r2=362856&view=diff > > > ========================================================================== > > ==== > > --- cfe/trunk/test/Sema/attr-nodebug.c (original) > > +++ cfe/trunk/test/Sema/attr-nodebug.c Fri Jun 7 17:01:21 2019 > > @@ -2,7 +2,7 @@ > > > > int a __attribute__((nodebug)); > > > > -void b(int p __attribute__((nodebug))) { // expected-warning {{'nodebug' > > attribute only applies to functions, function pointers, Objective-C > > methods, and variables}} > > +void b(int p __attribute__((nodebug))) { // expected-warning {{'nodebug' > > attribute only applies to typedefs, functions, function pointers, > > Objective-C methods, and variables}} > > int b __attribute__((nodebug)); > > } > > > > > > > > _______________________________________________ > > cfe-commits mailing list > > cfe-commits@lists.llvm.org > > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
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