[clang][DebugInfo] Emit DW_AT_language_{name, version} for DWARFv6 #163208
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dwblaikie
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Oct 13, 2025
clang/lib/CodeGen/CGDebugInfo.cpp
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| if (LO.CPlusPlus26) | ||
| LangVersion = 202400; // No official language code yet. | ||
| else if (LO.CPlusPlus23) | ||
| LangVersion = llvm::dwarf::DW_LANG_VERSION_C_plus_plus_23; |
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Part of the point of the spec being defined as it was was, I think, hopefully, that the DWARF emission could share the constants that the compiler already has/knows.
But I see that the constants are currently hardcoded literally into the __cplusplus macro emission or similary in InitPreprocessor.cpp - not exactly in a place that's reusable here...
But /maybe/ they could be generalized to some utility function that produces the number that could be shared between these two places?
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Yea that could make sense. I now also notice that this is the constant that a bunch of places check __cplus_plus against. I think it makes sense for there to be a shared utility, though I'm not sure what it would be keyed off of (and could be provided by the callosities in LLVM and Clang).
But we could make them constants in some shared header? Perhaps even in libc++ (though at that point those constant will need to be standardised, which they de-facto already are?) I pinged @ldionne about it
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I was just thinking of the parts of Clang that could share it - and build it out of the LangOpts, since that's how the current place is doing it, and how the place you're adding is doing it too.
__cplusplus and its values are defined in the C++ standard, [cpp.predefined]
For the uses in LLVM and libc++ - they're kind of defined by the standard as the interface between these systems, so I think it's fine to use it separately on both sides of that boundary.
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Ah gotcha. So a utility to go from LangOpts -> version code, so we don't duplicate the logic between the Clang and CGDebugInfo. And leave the constants in LLVM as-is, because they're standard anyway, so no need to make them named.
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Yep - sounds good to me.
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But we could make them constants in some shared header?
Do you mean constants defined as macros in a shared header? For example:
#define _LIBCPP_CPLUSPLUS17 201703L
#define _LIBCPP_CPLUSPLUS20 202002L
// etc..
Or do you mean actual static constexpr constants? If the former, I think there's not a huge benefit from the libc++ side to do that, since we already define macros like #if _LIBCPP_STD_VER <= 17 to do our version checks, so we don't hardcode 201703L anywhere. We have some uses that look like they are hardcoded in <version>, but that header is auto-generated from a script.
If you're suggesting the latter (static constexpr constants), then that's a non-starter because we need the ability to compare the value in preprocessor #ifs, and the preprocessor doesn't understand constant variables, only literals.
Please let me know if I've misunderstood your suggestion and my reply doesn't make sense.
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Do you mean constants defined as macros in a shared header?
Yea that's what I initially meant. But I agree it's not very compelling. We actually took a slightly different approach in #163348
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…gOptions (#163348) Motivated by this discussion: #163208 (comment) We will soon want to emit language version codes into debug-info. Instead of replicating the `LangOptions -> version code` mapping we thought we'd try to share some of the logic with the Clang frontend. This patch teaches `LangStandard` about language versions (currently just C++ and C).
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…es from LangOptions (#163348) Motivated by this discussion: llvm/llvm-project#163208 (comment) We will soon want to emit language version codes into debug-info. Instead of replicating the `LangOptions -> version code` mapping we thought we'd try to share some of the logic with the Clang frontend. This patch teaches `LangStandard` about language versions (currently just C++ and C).
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@llvm/pr-subscribers-clang-codegen @llvm/pr-subscribers-clang Author: Michael Buch (Michael137) ChangesDepends on:
Full diff: https://github.com/llvm/llvm-project/pull/163208.diff 11 Files Affected:
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 9fe9a13610296..79079ccb216cd 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -41,8 +41,10 @@
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
+#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
@@ -647,6 +649,77 @@ StringRef CGDebugInfo::getCurrentDirname() {
return CGM.getCodeGenOpts().DebugCompilationDir;
}
+static llvm::dwarf::SourceLanguage GetSourceLanguage(const CodeGenModule &CGM) {
+ const CodeGenOptions &CGO = CGM.getCodeGenOpts();
+ const LangOptions &LO = CGM.getLangOpts();
+
+ assert(CGO.DwarfVersion <= 5);
+
+ llvm::dwarf::SourceLanguage LangTag;
+ if (LO.CPlusPlus) {
+ if (LO.ObjC)
+ LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
+ else if (CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)
+ LangTag = llvm::dwarf::DW_LANG_C_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) {
+ LangTag = llvm::dwarf::DW_LANG_ObjC;
+ } else if (LO.OpenCL && (!CGO.DebugStrictDwarf || CGO.DwarfVersion >= 5)) {
+ LangTag = llvm::dwarf::DW_LANG_OpenCL;
+ } else if (LO.C11 && !(CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)) {
+ LangTag = llvm::dwarf::DW_LANG_C11;
+ } else if (LO.C99) {
+ LangTag = llvm::dwarf::DW_LANG_C99;
+ } else {
+ LangTag = llvm::dwarf::DW_LANG_C89;
+ }
+
+ return LangTag;
+}
+
+static std::pair<llvm::dwarf::SourceLanguageName, uint32_t>
+GetSourceLanguageName(const CodeGenModule &CGM) {
+ const CodeGenOptions &CGO = CGM.getCodeGenOpts();
+ const LangOptions &LO = CGM.getLangOpts();
+
+ assert(CGO.DwarfVersion >= 6);
+
+ uint32_t LangVersion = 0;
+ llvm::dwarf::SourceLanguageName LangTag;
+ if (LO.CPlusPlus) {
+ if (LO.ObjC) {
+ LangTag = llvm::dwarf::DW_LNAME_ObjC_plus_plus;
+ } else {
+ LangTag = llvm::dwarf::DW_LNAME_C_plus_plus;
+ LangVersion = LO.getCPlusPlusLangStd().value_or(0);
+ }
+ } else if (LO.ObjC) {
+ LangTag = llvm::dwarf::DW_LNAME_ObjC;
+ } else if (LO.OpenCL) {
+ LangTag = llvm::dwarf::DW_LNAME_OpenCL_C;
+ } else {
+ LangTag = llvm::dwarf::DW_LNAME_C;
+ LangVersion = LO.getCLangStd().value_or(0);
+ }
+
+ return {LangTag, LangVersion};
+}
+
+static llvm::DISourceLanguageName
+GetDISourceLanguageName(const CodeGenModule &CGM) {
+ // Emit pre-DWARFv6 language codes.
+ if (CGM.getCodeGenOpts().DwarfVersion < 6)
+ return llvm::DISourceLanguageName(GetSourceLanguage(CGM));
+
+ auto [LName, LVersion] = GetSourceLanguageName(CGM);
+ return llvm::DISourceLanguageName(LName, LVersion);
+}
+
void CGDebugInfo::CreateCompileUnit() {
SmallString<64> Checksum;
std::optional<llvm::DIFile::ChecksumKind> CSKind;
@@ -702,31 +775,6 @@ void CGDebugInfo::CreateCompileUnit() {
}
}
- llvm::dwarf::SourceLanguage LangTag;
- if (LO.CPlusPlus) {
- if (LO.ObjC)
- LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
- else if (CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)
- LangTag = llvm::dwarf::DW_LANG_C_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) {
- LangTag = llvm::dwarf::DW_LANG_ObjC;
- } else if (LO.OpenCL && (!CGM.getCodeGenOpts().DebugStrictDwarf ||
- CGM.getCodeGenOpts().DwarfVersion >= 5)) {
- LangTag = llvm::dwarf::DW_LANG_OpenCL;
- } else if (LO.C11 && !(CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)) {
- LangTag = llvm::dwarf::DW_LANG_C11;
- } else if (LO.C99) {
- LangTag = llvm::dwarf::DW_LANG_C99;
- } else {
- LangTag = llvm::dwarf::DW_LANG_C89;
- }
-
std::string Producer = getClangFullVersion();
// Figure out which version of the ObjC runtime we have.
@@ -787,7 +835,7 @@ void CGDebugInfo::CreateCompileUnit() {
// Create new compile unit.
TheCU = DBuilder.createCompileUnit(
- llvm::DISourceLanguageName(LangTag), CUFile,
+ GetDISourceLanguageName(CGM), CUFile,
CGOpts.EmitVersionIdentMetadata ? Producer : "",
CGOpts.OptimizationLevel != 0 || CGOpts.PrepareForLTO ||
CGOpts.PrepareForThinLTO,
@@ -1234,20 +1282,46 @@ llvm::DIType *CGDebugInfo::CreateType(const PointerType *Ty,
Ty->getPointeeType(), Unit);
}
-/// \return whether a C++ mangling exists for the type defined by TD.
-static bool hasCXXMangling(const TagDecl *TD, llvm::DICompileUnit *TheCU) {
- switch (TheCU->getSourceLanguage().getUnversionedName()) {
+static bool hasCXXMangling(llvm::dwarf::SourceLanguage Lang, bool IsTagDecl) {
+ switch (Lang) {
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);
+ return IsTagDecl;
default:
return false;
}
}
+static bool hasCXXMangling(llvm::dwarf::SourceLanguageName Lang,
+ bool IsTagDecl) {
+ switch (Lang) {
+ case llvm::dwarf::DW_LNAME_C_plus_plus:
+ return true;
+ case llvm::dwarf::DW_LNAME_ObjC_plus_plus:
+ return IsTagDecl;
+ default:
+ return false;
+ }
+}
+
+/// \return whether a C++ mangling exists for the type defined by TD.
+static bool hasCXXMangling(const TagDecl *TD, llvm::DICompileUnit *TheCU) {
+ const bool IsTagDecl = isa<CXXRecordDecl>(TD) || isa<EnumDecl>(TD);
+
+ if (llvm::DISourceLanguageName SourceLang = TheCU->getSourceLanguage();
+ SourceLang.hasVersionedName())
+ return hasCXXMangling(
+ static_cast<llvm::dwarf::SourceLanguageName>(SourceLang.getName()),
+ IsTagDecl);
+ else
+ return hasCXXMangling(
+ static_cast<llvm::dwarf::SourceLanguage>(SourceLang.getName()),
+ IsTagDecl);
+}
+
// Determines if the debug info for this tag declaration needs a type
// identifier. The purpose of the unique identifier is to deduplicate type
// information for identical types across TUs. Because of the C++ one definition
diff --git a/clang/test/DebugInfo/CXX/versioned-language.cpp b/clang/test/DebugInfo/CXX/versioned-language.cpp
new file mode 100644
index 0000000000000..a57531412db68
--- /dev/null
+++ b/clang/test/DebugInfo/CXX/versioned-language.cpp
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=5 -std=c++98 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageName" --implicit-check-not "sourceLanguageVersion"
+//
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++98 | FileCheck %s --check-prefix=CHECK-CPP98
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++03 | FileCheck %s --check-prefix=CHECK-CPP03
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++11 | FileCheck %s --check-prefix=CHECK-CPP11
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++14 | FileCheck %s --check-prefix=CHECK-CPP14
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++17 | FileCheck %s --check-prefix=CHECK-CPP17
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++20 | FileCheck %s --check-prefix=CHECK-CPP20
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++23 | FileCheck %s --check-prefix=CHECK-CPP23
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c++2c | FileCheck %s --check-prefix=CHECK-CPP2C
+
+int globalVar = 10;
+
+// CHECK-CPP98: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 199711
+// FIXME: C++03 technically has no official standard version code. From Clang's point of view C++03 and C++98 are interchangable.
+// CHECK-CPP03: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 199711
+// CHECK-CPP11: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 201103
+// CHECK-CPP14: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 201402
+// CHECK-CPP17: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 201703
+// CHECK-CPP20: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 202002
+// CHECK-CPP23: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 202302
+// CHECK-CPP2C: !DICompileUnit(sourceLanguageName: DW_LNAME_C_plus_plus, sourceLanguageVersion: 202400
diff --git a/clang/test/DebugInfo/Generic/versioned-language.c b/clang/test/DebugInfo/Generic/versioned-language.c
new file mode 100644
index 0000000000000..1faa7b4b56d4e
--- /dev/null
+++ b/clang/test/DebugInfo/Generic/versioned-language.c
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=5 -std=c99 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageName" --implicit-check-not "sourceLanguageVersion"
+//
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c89 | FileCheck %s --check-prefix=CHECK-C89 --implicit-check-not "sourceLanguageVersion"
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c99 | FileCheck %s --check-prefix=CHECK-C99
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c17 | FileCheck %s --check-prefix=CHECK-C17
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c23 | FileCheck %s --check-prefix=CHECK-C23
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 -std=c2y | FileCheck %s --check-prefix=CHECK-C2Y
+
+int globalVar = 10;
+
+// CHECK-C89: !DICompileUnit(sourceLanguageName: DW_LNAME_C,
+// CHECK-C99: !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 199901
+// CHECK-C11: !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 201112
+// CHECK-C17: !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 201710
+// CHECK-C23: !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 202311
+// CHECK-C2Y: !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 202400
diff --git a/clang/test/DebugInfo/ObjC/versioned-language.m b/clang/test/DebugInfo/ObjC/versioned-language.m
new file mode 100644
index 0000000000000..178c47bf8c841
--- /dev/null
+++ b/clang/test/DebugInfo/ObjC/versioned-language.m
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=5 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageName" --implicit-check-not "sourceLanguageVersion"
+//
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageVersion" --check-prefix=CHECK-OBJC
+
+int globalVar = 10;
+
+// CHECK-OBJC: !DICompileUnit(sourceLanguageName: DW_LNAME_ObjC,
diff --git a/clang/test/DebugInfo/ObjCXX/versioned-language.mm b/clang/test/DebugInfo/ObjCXX/versioned-language.mm
new file mode 100644
index 0000000000000..bfdce462b2bf1
--- /dev/null
+++ b/clang/test/DebugInfo/ObjCXX/versioned-language.mm
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=5 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageName" --implicit-check-not "sourceLanguageVersion"
+//
+// RUN: %clang_cc1 -emit-llvm %s -o - -debug-info-kind=limited -dwarf-version=6 \
+// RUN: | FileCheck %s --implicit-check-not "sourceLanguageVersion" --check-prefix=CHECK-OBJCXX
+
+int globalVar = 10;
+
+// CHECK-OBJCXX: !DICompileUnit(sourceLanguageName: DW_LNAME_ObjC_plus_plus,
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 7a3cd83cdd887..cf6328580fd21 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -5876,6 +5876,7 @@ bool LLParser::parseDICompileUnit(MDNode *&Result, bool IsDistinct) {
REQUIRED(file, MDField, (/* AllowNull */ false)); \
OPTIONAL(language, DwarfLangField, ); \
OPTIONAL(sourceLanguageName, DwarfSourceLangNameField, ); \
+ OPTIONAL(sourceLanguageVersion, MDUnsignedField, (0, UINT32_MAX)); \
OPTIONAL(producer, MDStringField, ); \
OPTIONAL(isOptimized, MDBoolField, ); \
OPTIONAL(flags, MDStringField, ); \
@@ -5905,10 +5906,15 @@ bool LLParser::parseDICompileUnit(MDNode *&Result, bool IsDistinct) {
return error(Loc, "can only specify one of 'language' and "
"'sourceLanguageName' on !DICompileUnit");
+ if (sourceLanguageVersion.Seen && !sourceLanguageName.Seen)
+ return error(Loc, "'sourceLanguageVersion' requires an associated "
+ "'sourceLanguageName' on !DICompileUnit");
+
Result = DICompileUnit::getDistinct(
Context,
language.Seen ? DISourceLanguageName(language.Val)
- : DISourceLanguageName(sourceLanguageName.Val, 0),
+ : DISourceLanguageName(sourceLanguageName.Val,
+ sourceLanguageVersion.Val),
file.Val, producer.Val, isOptimized.Val, flags.Val, runtimeVersion.Val,
splitDebugFilename.Val, emissionKind.Val, enums.Val, retainedTypes.Val,
globals.Val, imports.Val, macros.Val, dwoId.Val, splitDebugInlining.Val,
diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
index cdcf7a80ffac7..ed0443f599a44 100644
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -1860,7 +1860,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
break;
}
case bitc::METADATA_COMPILE_UNIT: {
- if (Record.size() < 14 || Record.size() > 22)
+ if (Record.size() < 14 || Record.size() > 23)
return error("Invalid record");
// Ignore Record[0], which indicates whether this compile unit is
@@ -1869,11 +1869,13 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
const auto LangVersionMask = (uint64_t(1) << 63);
const bool HasVersionedLanguage = Record[1] & LangVersionMask;
+ const uint32_t LanguageVersion = Record.size() > 22 ? Record[22] : 0;
auto *CU = DICompileUnit::getDistinct(
Context,
HasVersionedLanguage
- ? DISourceLanguageName(Record[1] & ~LangVersionMask, 0)
+ ? DISourceLanguageName(Record[1] & ~LangVersionMask,
+ LanguageVersion)
: DISourceLanguageName(Record[1]),
getMDOrNull(Record[2]), getMDString(Record[3]), Record[4],
getMDString(Record[5]), Record[6], getMDString(Record[7]), Record[8],
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 54e916e2dcfe1..8ff3aa9817571 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -2142,6 +2142,7 @@ void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
Record.push_back(N->getRangesBaseAddress());
Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
Record.push_back(VE.getMetadataOrNullID(N->getRawSDK()));
+ Record.push_back(Lang.hasVersionedName() ? Lang.getVersion() : 0);
Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
Record.clear();
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 2430d988ddb04..3908a78f48412 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2374,16 +2374,21 @@ static void writeDICompileUnit(raw_ostream &Out, const DICompileUnit *N,
Out << "!DICompileUnit(";
MDFieldPrinter Printer(Out, WriterCtx);
- auto Lang = N->getSourceLanguage();
- if (Lang.hasVersionedName())
+ DISourceLanguageName Lang = N->getSourceLanguage();
+
+ if (Lang.hasVersionedName()) {
Printer.printDwarfEnum(
"sourceLanguageName",
static_cast<llvm::dwarf::SourceLanguageName>(Lang.getName()),
dwarf::SourceLanguageNameString,
/* ShouldSkipZero */ false);
- else
+
+ Printer.printInt("sourceLanguageVersion", Lang.getVersion(),
+ /*ShouldSkipZero=*/true);
+ } else {
Printer.printDwarfEnum("language", Lang.getName(), dwarf::LanguageString,
/* ShouldSkipZero */ false);
+ }
Printer.printMetadata("file", N->getRawFile(), /* ShouldSkipNull */ false);
Printer.printString("producer", N->getProducer());
diff --git a/llvm/test/Assembler/dicompileunit-invalid-language-version.ll b/llvm/test/Assembler/dicompileunit-invalid-language-version.ll
new file mode 100644
index 0000000000000..b3794ac749f60
--- /dev/null
+++ b/llvm/test/Assembler/dicompileunit-invalid-language-version.ll
@@ -0,0 +1,25 @@
+; RUN: split-file %s %t
+; RUN: not llvm-as < %t/dw_lang_with_version.ll -disable-output 2>&1 | FileCheck %s --check-prefix=WRONG-ATTR
+; RUN: not llvm-as < %t/overflow.ll -disable-output 2>&1 | FileCheck %s --check-prefix=OVERFLOW
+; RUN: not llvm-as < %t/version_without_name.ll -disable-output 2>&1 | FileCheck %s --check-prefix=NO-NAME
+; RUN: not llvm-as < %t/negative.ll -disable-output 2>&1 | FileCheck %s --check-prefix=NEGATIVE
+
+; WRONG-ATTR: error: 'sourceLanguageVersion' requires an associated 'sourceLanguageName' on !DICompileUnit
+; OVERFLOW: error: value for 'sourceLanguageVersion' too large, limit is 4294967295
+; NEGATIVE: error: expected unsigned integer
+; NO-NAME: error: missing one of 'language' or 'sourceLanguageName', required for !DICompileUnit
+
+;--- dw_lang_with_version.ll
+!0 = distinct !DICompileUnit(language: DW_LANG_C, sourceLanguageVersion: 1,
+ file: !DIFile(filename: "", directory: ""))
+
+;--- overflow.ll
+!0 = distinct !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: 4294967298)
+
+;--- negative.ll
+!0 = distinct !DICompileUnit(sourceLanguageName: DW_LNAME_C, sourceLanguageVersion: -1,
+ file: !DIFile(filename: "", directory: ""))
+
+;--- version_without_name.ll
+!0 = distinct !DICompileUnit(sourceLanguageVersion: 1,
+ file: !DIFile(filename: "", directory: ""))
diff --git a/llvm/test/Bitcode/dwarf-source-language-version.ll b/llvm/test/Bitcode/dwarf-source-language-version.ll
new file mode 100644
index 0000000000000..311afd5a99afe
--- /dev/null
+++ b/llvm/test/Bitcode/dwarf-source-language-version.ll
@@ -0,0 +1,17 @@
+; RUN: llvm-as < %s | llvm-dis | llvm-as | llvm-dis | FileCheck %s --implicit-check-not "sourceLanguageVersion: 0"
+
+; CHECK: sourceLanguageVersion: 120
+
+source_filename = "cu.cpp"
+target triple = "arm64-apple-macosx"
+
+!llvm.dbg.cu = !{!0, !5}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(sourceLanguageName: DW_LNAME_ObjC_plus_plus, sourceLanguageVersion: 120, file: !1, producer: "handwritten", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2, splitDebugInlining: false, nameTableKind: Apple, sysroot: "/")
+!1 = !DIFile(filename: "cu.cpp", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DICompileUnit(sourceLanguageName: DW_LNAME_ObjC_plus_plus, sourceLanguageVersion: 0, file: !6, producer: "handwritten", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2, splitDebugInlining: false, nameTableKind: Apple, sysroot: "/")
+!6 = !DIFile(filename: "cu2.cpp", directory: "/tmp")
|
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Oct 15, 2025
clang/lib/CodeGen/CGDebugInfo.cpp
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| if (CGM.getCodeGenOpts().DwarfVersion < 6) | ||
| return llvm::DISourceLanguageName(GetSourceLanguage(CGM)); | ||
|
|
||
| auto [LName, LVersion] = GetSourceLanguageName(CGM); |
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Maybe inline GetSourceLanguageName here - since this is the only caller & doesn't seem much benefit to having a std::pair result that then has to be remapped into the DISourceLanguageName.
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Depends on:
With this patch Clang will start emitting
DW_AT_language_{name, version}for C++/C/Objective-C/Objective-C++ when using-gdwarf-6. We adjust theDISourceLanguageName(which we pass toDICompileUnit) to hold aDW_AT_language_name_and version code when in DWARFv6. Otherwise we continue using theDW_LANG_version ofDISourceLanguageName.We didn't back-port emitting
DW_AT_language_name/DW_AT_language_versionto DWARFv5 (unlike GCC, which emits both the new and old language attributes in DWARFv5) because there wasn't a compelling reason to do so (yet).