[DWARF-5] Support for DWARF-5 C++ language tags

[SouraVX]

Summary

This patch provides support for DW_LANG_C_plus_plus_11, DW_LANG_C_plus_plus_14 tags in clang C++ frontend.

[aprantl]

include/clang/AST/DeclCXX.h

2931

I understand that DWARF does not define a C++17 language constant, but in the AST I fell like we should represent it, even if it is being lowered into C++14 for the debug info.

lib/AST/DeclPrinter.cpp

1009

Can you turn this into a switch() statement?

1010

Why this weird spelling with the underscore?

[SouraVX]

include/clang/AST/DeclCXX.h

2931

It's represented in AST as enum in LangStandard.h file. We didn't add it here, as DWARF5 has no opcode for C++17. If we add it here some opcode, this might cause conflict with future upcoming DWARF standard.

lib/AST/DeclPrinter.cpp

1009

Done

[SouraVX]

Removed underscores from names.

[aprantl]

include/clang/AST/DeclCXX.h

2931

Since these are the DWARF DW_lang constants, we shouldn't repeat their numeric values here. Can we write this as
lang_c = llvm::dwarf::DW_LANG_C, etc?

[SouraVX]

include/clang/AST/DeclCXX.h

2931

We can do this, but not sure whether, we should do this in AST ?
Since it's a language specific part, if we integrate this from DWARF opcodes it will unnecessary pollute AST ? Other language opcodes will also be visible here.

[aprantl]

include/clang/AST/DeclCXX.h

2931

I'm not sure I understand the concern here. Are you worried about #Including "llvm/BinaryFormat/DWARF.h" and making these definitions visible to users of DeclCXX.h? All symbols there are in a separate namespace.

[SouraVX]

include/clang/AST/DeclCXX.h

2931

Thanks @aprantl for your review.
I was sceptical about, introducing DWARF related changes to AST, however you're correct, those are just language enums.
This will be heplfull in future, while adding language tag. If more C/C++ versions become part of DWARF standard.
Will address this change in next revision.

[SouraVX]

Updated AST to use DWARF language enums.

[aprantl]

Please be sure the watch the lldb (and other debugger) bots after committing this..

[SouraVX]

In D67613#1674597, @aprantl wrote:

Please be sure the watch the lldb (and other debugger) bots after committing this..

Thanks a lot!

[SouraVX]

In D67613#1674902, @SouraVX wrote:

In D67613#1674597, @aprantl wrote:

Please be sure the watch the lldb (and other debugger) bots after committing this..

Thanks a lot!

@aprantl , Could you commit these changes, I don't have commit access rights.
Thanks!

[SouraVX]

In D67613#1674597, @aprantl wrote:

Please be sure the watch the lldb (and other debugger) bots after committing this..

Could you please commit these changes.
Thanks!

[xbolva00]

/srv/llvm-buildbot-srcatch/llvm-build-dir/clang-x86_64-debian-fast/llvm.src/tools/clang/tools/extra/modularize/Modularize.cpp:583:13: warning: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Wswitch]
1 warning generated.

[JDevlieghere]

I reverted this in r372672 because it caused a test failure in LLDB: http://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/1748/

[uabelho]

In D67613#1679879, @xbolva00 wrote:

/srv/llvm-buildbot-srcatch/llvm-build-dir/clang-x86_64-debian-fast/llvm.src/tools/clang/tools/extra/modularize/Modularize.cpp:583:13: warning: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Wswitch]
1 warning generated.

We also get that warning when compiling with clang 8:

../../clang-tools-extra/modularize/Modularize.cpp:583:13: error: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Werror,-Wswitch]
    switch (D->getLanguage()) {
            ^
1 error generated.

[uabelho]

In D67613#1680176, @uabelho wrote:

In D67613#1679879, @xbolva00 wrote:

/srv/llvm-buildbot-srcatch/llvm-build-dir/clang-x86_64-debian-fast/llvm.src/tools/clang/tools/extra/modularize/Modularize.cpp:583:13: warning: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Wswitch]
1 warning generated.

We also get that warning when compiling with clang 8:

../../clang-tools-extra/modularize/Modularize.cpp:583:13: error: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Werror,-Wswitch]
    switch (D->getLanguage()) {
            ^
1 error generated.

I did something about it in r372714. Please take a look and see if it should be fixed differently.

[SouraVX]

In D67613#1680176, @uabelho wrote:

In D67613#1679879, @xbolva00 wrote:

/srv/llvm-buildbot-srcatch/llvm-build-dir/clang-x86_64-debian-fast/llvm.src/tools/clang/tools/extra/modularize/Modularize.cpp:583:13: warning: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Wswitch]
1 warning generated.

We also get that warning when compiling with clang 8:

../../clang-tools-extra/modularize/Modularize.cpp:583:13: error: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Werror,-Wswitch]
    switch (D->getLanguage()) {
            ^
1 error generated.

In D67613#1680398, @uabelho wrote:

In D67613#1680176, @uabelho wrote:

In D67613#1679879, @xbolva00 wrote:

/srv/llvm-buildbot-srcatch/llvm-build-dir/clang-x86_64-debian-fast/llvm.src/tools/clang/tools/extra/modularize/Modularize.cpp:583:13: warning: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Wswitch]
1 warning generated.

We also get that warning when compiling with clang 8:

../../clang-tools-extra/modularize/Modularize.cpp:583:13: error: enumeration values 'lang_cxx_11' and 'lang_cxx_14' not handled in switch [-Werror,-Wswitch]
    switch (D->getLanguage()) {
            ^
1 error generated.

I did something about it in r372714. Please take a look and see if it should be fixed differently.

Hi Thanks for doing this, I got occupied by something else. that seems good.
Thanks again!

include/clang/AST/DeclCXX.h

 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"

   /// ensure a stable ABI for this, we choose the DW_LANG_ encodings
   /// from the dwarf standard.
   enum LanguageIDs {
-    lang_c = /* DW_LANG_C */ 0x0002,
-    lang_cxx = /* DW_LANG_C_plus_plus */ 0x0004
+    lang_c = llvm::dwarf::DW_LANG_C,
+    lang_cxx = llvm::dwarf::DW_LANG_C_plus_plus,
+    lang_cxx_11 = llvm::dwarf::DW_LANG_C_plus_plus_11,
+    lang_cxx_14 = llvm::dwarf::DW_LANG_C_plus_plus_14
   };
 
 private:

lib/AST/DeclPrinter.cpp

 
 void DeclPrinter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
   const char *l;
-  if (D->getLanguage() == LinkageSpecDecl::lang_c)
+  switch (D->getLanguage()) {
+  case LinkageSpecDecl::lang_c:
     l = "C";
-  else {
-    assert(D->getLanguage() == LinkageSpecDecl::lang_cxx &&
-           "unknown language in linkage specification");
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    l = "C++14";
+    break;
+  case LinkageSpecDecl::lang_cxx_11:
+    l = "C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx:
     l = "C++";
+    break;
+  default:
+    llvm_unreachable("Unknown language in linkage specification");
+    break;
   }
 
   Out << "extern \"" << l << "\" ";

lib/AST/JSONNodeDumper.cpp

   switch (LSD->getLanguage()) {
   case LinkageSpecDecl::lang_c: Lang = "C"; break;
   case LinkageSpecDecl::lang_cxx: Lang = "C++"; break;
+  case LinkageSpecDecl::lang_cxx_11:
+    Lang = "C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    Lang = "C++14";
+    break;
   }
   JOS.attribute("language", Lang);
   attributeOnlyIfTrue("hasBraces", LSD->hasBraces());

lib/AST/TextNodeDumper.cpp

   case LinkageSpecDecl::lang_cxx:
     OS << " C++";
     break;
+  case LinkageSpecDecl::lang_cxx_11:
+    OS << " C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    OS << " C++14";
+    break;
   }
 }
 

lib/CodeGen/CGDebugInfo.cpp

   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
+    else if (LO.CPlusPlus14)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
+    else if (LO.CPlusPlus11)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
   } else if (LO.ObjC) {

 static bool hasCXXMangling(const TagDecl *TD, llvm::DICompileUnit *TheCU) {
   switch (TheCU->getSourceLanguage()) {
   case llvm::dwarf::DW_LANG_C_plus_plus:
+  case llvm::dwarf::DW_LANG_C_plus_plus_11:
+  case llvm::dwarf::DW_LANG_C_plus_plus_14:
     return true;
   case llvm::dwarf::DW_LANG_ObjC_plus_plus:
     return isa<CXXRecordDecl>(TD) || isa<EnumDecl>(TD);

lib/CodeGen/CodeGenModule.cpp

 // EmitLinkageSpec - Emit all declarations in a linkage spec.
 void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
   if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
-      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx &&
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx_11 &&
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx_14) {
     ErrorUnsupported(LSD, "linkage spec");
     return;
   }

lib/Sema/SemaDeclCXX.cpp

     Language = LinkageSpecDecl::lang_c;
   else if (Lang == "C++")
     Language = LinkageSpecDecl::lang_cxx;
+  else if (Lang == "C++11")
+    Language = LinkageSpecDecl::lang_cxx_11;
+  else if (Lang == "C++14")
+    Language = LinkageSpecDecl::lang_cxx_14;
   else {
     Diag(LangStr->getExprLoc(), diag::err_language_linkage_spec_unknown)
       << LangStr->getSourceRange();

lib/Sema/SemaModule.cpp

         ExternCLoc = LSD->getBeginLoc();
       break;
     case LinkageSpecDecl::lang_cxx:
+    case LinkageSpecDecl::lang_cxx_11:
+    case LinkageSpecDecl::lang_cxx_14:
       break;
     }
     DC = LSD->getParent();

test/Modules/ModuleDebugInfo.cpp

 
 // PCH:
 // RUN: %clang_cc1 -triple %itanium_abi_triple -x c++ -std=c++11  -debugger-tuning=lldb -emit-pch -fmodule-format=obj -I %S/Inputs -o %t.pch %S/Inputs/DebugCXX.h -mllvm -debug-only=pchcontainer &>%t-pch.ll
-// RUN: cat %t-pch.ll | FileCheck %s
+// RUN: cat %t-pch.ll | FileCheck --check-prefix=CHECK-CXX %s
 // RUN: cat %t-pch.ll | FileCheck --check-prefix=CHECK-NEG %s
 
 #ifdef MODULES

 // CHECK-MOD: distinct !DICompileUnit(language: DW_LANG_{{.*}}C_plus_plus,
 
 // CHECK: distinct !DICompileUnit(language: DW_LANG_{{.*}}C_plus_plus,
+// CHECK-CXX: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_11,
 // CHECK-SAME:                    isOptimized: false,
 // CHECK-NOT:                     splitDebugFilename:
 // CHECK-SAME:                    dwoId: