[OpenCL] Use DW_LANG_OpenCL language tag for OpenCL C

[stuart]

Summary

Note regarding C++ for OpenCL:

When compiling C++ for OpenCL, DW_LANG_C_plus_plus* is emitted.

There is no DWARF language code defined for C++ for OpenCL as of yet, but DWARF issue 210514.1 has been raised to request one.

In the mean time, continuing to emit DW_LANG_C_plus_plus* for C++ for OpenCL allows the potential to distinguish between C++ for OpenCL and OpenCL C in !DICompileUnit nodes, whereas using DW_LANG_OpenCL for C++ for OpenCL would prevent this.

This change therefore leaves C++ for OpenCL as-is.

[stuart]

Note: there is currently no DWARF language code defined for C++ for OpenCL, so we must use DW_LANG_C_plus_plus* if we wish to be able to determine whether output has been generated from C++ for OpenCL source or from OpenCL C source. I have raised DWARF issue 210514.1 to add a dedicated C++ for OpenCL code in the next version of DWARF, but for now I believe that it is best to use DW_LANG_OpenCL for OpenCL C only, and not for C++ for OpenCL.

I could perhaps add a note regarding this to the commit message but am concerned about overcomplicating the message.

[stuart]

Add missing trailing commas to CHECK lines of FileCheck test.

[SouraVX]

In D104118#2813358, @stuart wrote:

Note: there is currently no DWARF language code defined for C++ for OpenCL, so we must use DW_LANG_C_plus_plus* if we wish to be able to determine whether output has been generated from C++ for OpenCL source or from OpenCL C source. I have raised DWARF issue 210514.1 to add a dedicated C++ for OpenCL code in the next version of DWARF, but for now I believe that it is best to use DW_LANG_OpenCL for OpenCL C only, and not for C++ for OpenCL.

I could perhaps add a note regarding this to the commit message but am concerned about overcomplicating the message.

NIT: It would be nice to have this as part of the commit summary/message itself. Min. at least the DWARF issue part.

[shchenz]

clang/lib/CodeGen/CGDebugInfo.cpp

579

I think for non-strict DWARF mode, we still can generate DW_LANG_OpenCL for the DWARF version lower than 5? Seems we also need to fix above DW_LANG_C_plus_plus_14 and DW_LANG_C_plus_plus_11

[stuart]

clang/lib/CodeGen/CGDebugInfo.cpp

579

If we have a -gstrict-dwarf option for this, then it would seem better to add DW_LANG_C_plus_plus_17 and DW_LANG_C_plus_plus_20 definitions and generate those for the !CGM.getCodeGenOpts().DebugStrictDwarf case. C++ for OpenCL would then use one of the more recent language tag values for the time being (without any special logic).

[shchenz]

clang/lib/CodeGen/CGDebugInfo.cpp

579

I added a patch https://reviews.llvm.org/D104291 for DW_LANG_C_plus_plus_14 and DW_LANG_C_plus_plus_11.
I think DW_LANG_OpenCL should be in the same situation?

[stuart]

clang/lib/CodeGen/CGDebugInfo.cpp

579

Thanks. I will wait until D104291 is accepted, and then update this change correspondingly. Yes, I believe DW_LANG_OpenCL is in the same situation.

Looking more closely, I notice that DW_LANG_RenderScript was also introduced in DWARF 5, and we don't use it (at all) in Clang, but instead use the vendor-specific DW_LANG_GOOGLE_RenderScript value. It should probably fall back to the vendor-specific value if the DWARF 5 value is not available, instead.

[stuart]

Changes will be required to align this with D104291.

[stuart]

Added handling of -gstrict-dwarf and updated tests accordingly.

[shchenz]

LGTM. Thanks.

[Anastasia]

LGTM! Thanks!

[stuart]

On reflection, I don't think it makes sense to make use of DW_LANG_C_plus_plus_17 or DW_LANG_C_plus_plus_20 in Clang just yet, as these are generally not supported by other tooling. I am a bit confused by DWARF publishing these tags ahead of time, yet tooling having not been updated to recognize them. Regardless, it is clear that support in debuggers needs to come first, which is something that I am not planning to add.

clang/lib/CodeGen/CGDebugInfo.cpp

if (LO.CPlusPlus) {
     else if (LO.CPlusPlus14 && CGM.getCodeGenOpts().DwarfVersion >= 5)
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
     else if (LO.CPlusPlus11 && CGM.getCodeGenOpts().DwarfVersion >= 5)
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
   } else if (LO.ObjC) {
     LangTag = llvm::dwarf::DW_LANG_ObjC;
+  } else if (LO.OpenCL && CGM.getCodeGenOpts().DwarfVersion >= 5) {
+    LangTag = llvm::dwarf::DW_LANG_OpenCL;
   } else if (LO.RenderScript) {
     LangTag = llvm::dwarf::DW_LANG_GOOGLE_RenderScript;
   } else if (LO.C99) {
     LangTag = llvm::dwarf::DW_LANG_C99;
   } else {
     LangTag = llvm::dwarf::DW_LANG_C89;
   }
 

clang/test/CodeGenOpenCL/debug-info-programming-language.cl

+// RUN: %clang_cc1 -dwarf-version=5  -emit-llvm -triple %itanium_abi_triple %s -o - \
+// RUN:   -x cl -O0 -disable-llvm-passes -debug-info-kind=limited \
+// RUN: | FileCheck --check-prefix=CHECK-DWARF5 %s
+// RUN: %clang_cc1 -dwarf-version=3  -emit-llvm -triple %itanium_abi_triple %s -o - \
+// RUN:   -x cl -O0 -disable-llvm-passes -debug-info-kind=limited \
+// RUN: | FileCheck --check-prefix=CHECK-DWARF3 %s
+
+kernel void empty() {}
+
+// CHECK-DWARF5: distinct !DICompileUnit(language: DW_LANG_OpenCL
+// CHECK-DWARF3: distinct !DICompileUnit(language: DW_LANG_C99