Use fully qualified name when printing S_CONSTANT records

[akhuang]

Summary

Before it was using the fully qualified name only for static data members.
Now it does for all variable names to match MSVC.

[akhuang]

Add case for enums in classes.

[rnk]

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

3080–3081 ↗

(On Diff #203609)

This seems like it would do the wrong thing for a regular constant that isn't an enum, but which has an enum type. This kind of thing:

namespace Bar {
enum Foo { FooA, FooB };
}
const Bar::Foo foo_gv = Bar::FooA;

... might come out as Bar::foo_gv when it should be just foo_gv.

I'm not actually sure what to do in this case, because we made enumerators look a lot like const ints, that was the whole idea. I mean, we could change clang to make them look like static const data members, I guess, but that seems like a step too far.

[akhuang]

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

3080–3081 ↗

(On Diff #203609)

It happens to do the right thing here because the type for global constants is a const tag.. but this seems kind of unreliable.

Other than making them look like static const data members or adding some enum type to the DIGlobalVariable, I can't really think of a good way to do this other than making the scope not global?

[rnk]

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

3080–3081 ↗

(On Diff #203609)

Making the scope not global seems like the most logical thing to me. It sounds like there's no particularly good reason why we use the global scope for static data members, other than that's the DWARF we want to emit, so we can go ahead and revise that decision for enums.

[akhuang]

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

3080–3081 ↗

(On Diff #203609)

Actually, enums in classes currently have global scope, so maybe that won't work

[akhuang]

Change to not emit DIGlobalVariable for enums when they are defined in a class, which
matches MSVC's behavior and gets around the issue of having to create a name with scope.

[rnk]

lgtm

cfe/trunk/lib/CodeGen/CGDebugInfo.cpp

void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD, const APValue &Init) {
   if (VD->hasAttr<NoDebugAttr>())
     return;
   auto Align = getDeclAlignIfRequired(VD, CGM.getContext());
   // Create the descriptor for the variable.
   llvm::DIFile *Unit = getOrCreateFile(VD->getLocation());
   StringRef Name = VD->getName();
   llvm::DIType *Ty = getOrCreateType(VD->getType(), Unit);
 
-  // Do not use global variables for enums, unless for CodeView.
+  // Do not use global variables for enums, unless in CodeView.
   if (const auto *ECD = dyn_cast<EnumConstantDecl>(VD)) {
     const auto *ED = cast<EnumDecl>(ECD->getDeclContext());
     assert(isa<EnumType>(ED->getTypeForDecl()) && "Enum without EnumType?");
     (void)ED;
 
-    if (!CGM.getCodeGenOpts().EmitCodeView)
+    // If CodeView, emit enums as global variables, unless they are defined
+    // inside a class. We do this because MSVC doesn't emit S_CONSTANTs for
+    // enums in classes, and because it is difficult to attach this scope
+    // information to the global variable.
+    if (!CGM.getCodeGenOpts().EmitCodeView ||
+        isa<RecordDecl>(ED->getDeclContext()))
       return;
   }
 
   llvm::DIScope *DContext = nullptr;
 
   // Do not emit separate definitions for function local consts.
   if (isa<FunctionDecl>(VD->getDeclContext()))
     return;

llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

if (const GlobalVariable *GV =
     uint8_t data[10];
     BinaryStreamWriter Writer(data, llvm::support::endianness::little);
     CodeViewRecordIO IO(Writer);
     cantFail(IO.mapEncodedInteger(Val));
     StringRef SRef((char *)data, Writer.getOffset());
     OS.EmitBinaryData(SRef);
 
     OS.AddComment("Name");
-    // Get fully qualified name if global is a static data member.
-    std::string Name = DIGV->getDisplayName();
+    const DIScope *Scope = DIGV->getScope();
+    // For static data members, get the scope from the declaration.
     if (const auto *MemberDecl = dyn_cast_or_null<DIDerivedType>(
             DIGV->getRawStaticDataMemberDeclaration()))
-      Name = getFullyQualifiedName(MemberDecl->getScope(), Name);
-    emitNullTerminatedSymbolName(OS, Name);
+      Scope = MemberDecl->getScope();
+    emitNullTerminatedSymbolName(OS,
+                                 getFullyQualifiedName(Scope, DIGV->getName()));
     endSymbolRecord(SConstantEnd);
   }
 }

llvm/trunk/test/DebugInfo/COFF/global-constants.ll

 ; RUN: llc < %s | FileCheck %s --check-prefix=ASM
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s --check-prefix=OBJ
 
 ; C++ source to regenerate:
+; namespace Test1 {
 ; const float TestConst1 = 3.14;
+; }
 ; struct S {
 ;   static const int TestConst2 = -10;
+;   enum { SEnum = 42 };
 ; }
 ; enum TestEnum : int {
 ;    ENUM_A = 2147000000,
 ;    ENUM_B = -2147000000,
 ; };
 ; void useConst(int);
 ; void foo() {
-;   useConst(TestConst1);
+;   useConst(Test1::TestConst1);
 ;   useConst(S::TestConst2);
 ;   useConst(ENUM_B);
+;   useConst(S::SEnum);
 ; }
 ; $ clang t.cpp -S -emit-llvm -g -gcodeview -o t.ll
 
 ; ASM-LABEL:  .long 241                     # Symbol subsection for globals
 ; ASM:        .short {{.*-.*}}              # Record length
 ; ASM:        .short 4359                   # Record kind: S_CONSTANT
-; ASM-NEXT:   .long 4099                    # Type
+; ASM-NEXT:   .long 4102                    # Type
 ; ASM-NEXT:   .byte 0x04, 0x80, 0xc3, 0xf5  # Value
 ; ASM-NEXT:   .byte 0x48, 0x40
-; ASM-NEXT:   .asciz "TestConst1"           # Name
+; ASM-NEXT:   .asciz "Test1::TestConst1"    # Name
 ; ASM:        .short {{.*-.*}}              # Record length
 ; ASM:        .short 4359                   # Record kind: S_CONSTANT
-; ASM-NEXT:   .long 4100                    # Type
+; ASM-NEXT:   .long 4103                    # Type
 ; ASM-NEXT:   .byte 0x61, 0x00              # Value
 ; ASM-NEXT:   .asciz "S::TestConst2"        # Name
 ; ASM:        .short {{.*-.*}}              # Record length
 ; ASM:        .short 4359                   # Record kind: S_CONSTANT
-; ASM-NEXT:   .long 4102                    # Type
+; ASM-NEXT:   .long 4105                    # Type
 ; ASM-NEXT:   .byte 0x0a, 0x80, 0x40, 0x61  # Value
 ; ASM-NEXT:   .byte 0x07, 0x80, 0xff, 0xff
 ; ASM-NEXT:   .byte 0xff, 0xff
 ; ASM-NEXT:   .asciz "ENUM_B"               # Name
+; ASM-NOT:    .asciz "S::SEnum"             # Name
 
 ; OBJ:        CodeViewDebugInfo [
 ; OBJ:          Section: .debug$S
 ; OBJ:          Magic: 0x4
 ; OBJ:          Subsection [
 ; OBJ:            SubSectionType: Symbols (0xF1)
 ; OBJ:            ConstantSym {
 ; OBJ-NEXT:         Kind: S_CONSTANT (0x1107)
-; OBJ-NEXT:         Type: const float (0x1003)
+; OBJ-NEXT:         Type: const float (0x1006)
 ; OBJ-NEXT:         Value: 1078523331
-; OBJ-NEXT:         Name: TestConst1
+; OBJ-NEXT:         Name: Test1::TestConst1
 ; OBJ-NEXT:       }
 ; OBJ-NEXT:       ConstantSym {
 ; OBJ-NEXT:         Kind: S_CONSTANT (0x1107)
-; OBJ-NEXT:         Type: const char (0x1004)
+; OBJ-NEXT:         Type: const char (0x1007)
 ; OBJ-NEXT:         Value: 97
 ; OBJ-NEXT:         Name: S::TestConst2
 ; OBJ-NEXT:       }
 ; OBJ-NEXT:       ConstantSym {
 ; OBJ-NEXT:         Kind: S_CONSTANT (0x1107)
-; OBJ-NEXT:         Type: TestEnum (0x1006)
+; OBJ-NEXT:         Type: TestEnum (0x1009)
 ; OBJ-NEXT:         Value: 18446744071562551616
 ; OBJ-NEXT:         Name: ENUM_B
 ; OBJ-NEXT:       }
-
+; OBJ-NOT:          Name: S::SEnum
 
 ; ModuleID = 't.cpp'
 source_filename = "t.cpp"
 target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-w64-windows-gnu"
+target triple = "x86_64-pc-windows-msvc19.16.27030"
 
-; Function Attrs: noinline nounwind optnone
-define dso_local void @_Z3foov() #0 !dbg !28 {
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @"?useConst@@YAXH@Z"(i32) #0 !dbg !32 {
 entry:
-  call void @_Z8useConsti(i32 3), !dbg !32
-  call void @_Z8useConsti(i32 97), !dbg !33
-  call void @_Z8useConsti(i32 -2147000000), !dbg !34
-  ret void, !dbg !35
+  %.addr = alloca i32, align 4
+  store i32 %0, i32* %.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %.addr, metadata !36, metadata !DIExpression()), !dbg !37
+  ret void, !dbg !37
 }
 
-declare dso_local void @_Z8useConsti(i32) #1
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: noinline norecurse nounwind optnone uwtable
+define dso_local i32 @main() #2 !dbg !38 {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  call void @"?useConst@@YAXH@Z"(i32 3), !dbg !41
+  call void @"?useConst@@YAXH@Z"(i32 97), !dbg !42
+  call void @"?useConst@@YAXH@Z"(i32 -2147000000), !dbg !43
+  call void @"?useConst@@YAXH@Z"(i32 42), !dbg !44
+  call void @llvm.debugtrap(), !dbg !45
+  ret i32 0, !dbg !46
+}
+
+; Function Attrs: nounwind
+declare void @llvm.debugtrap() #3
+
+attributes #0 = { noinline nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone speculatable }
+attributes #2 = { noinline norecurse nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { nounwind }
 
 !llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!24, !25, !26}
-!llvm.ident = !{!27}
+!llvm.module.flags = !{!27, !28, !29, !30}
+!llvm.ident = !{!31}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 9.0.0 (https://github.com/llvm/llvm-project.git dee1891507401f396290b5d9cb5717d6b0755337)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !9, globals: !15, nameTableKind: None)
-!1 = !DIFile(filename: "<stdin>", directory: "C:\5Csrc\5Ctest", checksumkind: CSK_MD5, checksum: "6d700c7d582557a012214ac1f1f8721b")
-!2 = !{!3}
-!3 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "TestEnum", file: !4, line: 5, baseType: !5, size: 32, elements: !6, identifier: "_ZTS8TestEnum")
-!4 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Ctest", checksumkind: CSK_MD5, checksum: "6d700c7d582557a012214ac1f1f8721b")
-!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!6 = !{!7, !8}
-!7 = !DIEnumerator(name: "ENUM_A", value: 2147000000)
-!8 = !DIEnumerator(name: "ENUM_B", value: -2147000000)
-!9 = !{!10}
-!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !4, line: 2, size: 8, flags: DIFlagTypePassByValue, elements: !11, identifier: "_ZTS1S")
-!11 = !{!12}
-!12 = !DIDerivedType(tag: DW_TAG_member, name: "TestConst2", scope: !10, file: !4, line: 3, baseType: !13, flags: DIFlagStaticMember, extraData: i8 97)
-!13 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !14)
-!14 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
-!15 = !{!16, !20, !22}
-!16 = !DIGlobalVariableExpression(var: !17, expr: !DIExpression(DW_OP_constu, 1078523331, DW_OP_stack_value))
-!17 = distinct !DIGlobalVariable(name: "TestConst1", scope: !0, file: !4, line: 1, type: !18, isLocal: true, isDefinition: true)
-!18 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !19)
-!19 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
-!20 = !DIGlobalVariableExpression(var: !21, expr: !DIExpression(DW_OP_constu, 97, DW_OP_stack_value))
-!21 = distinct !DIGlobalVariable(name: "TestConst2", scope: !0, file: !4, line: 3, type: !13, isLocal: true, isDefinition: true, declaration: !12)
-!22 = !DIGlobalVariableExpression(var: !23, expr: !DIExpression(DW_OP_constu, 18446744071562551616, DW_OP_stack_value))
-!23 = distinct !DIGlobalVariable(name: "ENUM_B", scope: !0, file: !4, line: 7, type: !3, isLocal: true, isDefinition: true)
-!24 = !{i32 2, !"CodeView", i32 1}
-!25 = !{i32 2, !"Debug Info Version", i32 3}
-!26 = !{i32 1, !"wchar_size", i32 2}
-!27 = !{!"clang version 9.0.0 (https://github.com/llvm/llvm-project.git dee1891507401f396290b5d9cb5717d6b0755337)"}
-!28 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !4, file: !4, line: 10, type: !29, scopeLine: 10, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !31)
-!29 = !DISubroutineType(types: !30)
-!30 = !{null}
-!31 = !{}
-!32 = !DILocation(line: 11, scope: !28)
-!33 = !DILocation(line: 12, scope: !28)
-!34 = !DILocation(line: 13, scope: !28)
-!35 = !DILocation(line: 14, scope: !28)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 9.0.0 (https://github.com/llvm/llvm-project.git f60f863075c7056f26e701b0405fc5752f0db576)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !16, globals: !17, nameTableKind: None)
+!1 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Ctesting", checksumkind: CSK_MD5, checksum: "70da26ef1009521e2127bf71f8d532a2")
+!2 = !{!3, !12}
+!3 = !DICompositeType(tag: DW_TAG_enumeration_type, scope: !4, file: !1, line: 6, baseType: !9, size: 32, elements: !10, identifier: ".?AW4<unnamed-enum-SEnum>@S@@")
+!4 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !1, line: 4, size: 8, flags: DIFlagTypePassByValue, elements: !5, identifier: ".?AUS@@")
+!5 = !{!6, !3}
+!6 = !DIDerivedType(tag: DW_TAG_member, name: "TestConst2", scope: !4, file: !1, line: 5, baseType: !7, flags: DIFlagStaticMember, extraData: i8 97)
+!7 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !8)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{!11}
+!11 = !DIEnumerator(name: "SEnum", value: 42)
+!12 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "TestEnum", file: !1, line: 8, baseType: !9, size: 32, elements: !13, identifier: ".?AW4TestEnum@@")
+!13 = !{!14, !15}
+!14 = !DIEnumerator(name: "ENUM_A", value: 2147000000)
+!15 = !DIEnumerator(name: "ENUM_B", value: -2147000000)
+!16 = !{!4}
+!17 = !{!18, !23, !25}
+!18 = !DIGlobalVariableExpression(var: !19, expr: !DIExpression(DW_OP_constu, 1078523331, DW_OP_stack_value))
+!19 = distinct !DIGlobalVariable(name: "TestConst1", scope: !20, file: !1, line: 2, type: !21, isLocal: true, isDefinition: true)
+!20 = !DINamespace(name: "Test1", scope: null)
+!21 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !22)
+!22 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+!23 = !DIGlobalVariableExpression(var: !24, expr: !DIExpression(DW_OP_constu, 97, DW_OP_stack_value))
+!24 = distinct !DIGlobalVariable(name: "TestConst2", scope: !0, file: !1, line: 5, type: !7, isLocal: true, isDefinition: true, declaration: !6)
+!25 = !DIGlobalVariableExpression(var: !26, expr: !DIExpression(DW_OP_constu, 18446744071562551616, DW_OP_stack_value))
+!26 = distinct !DIGlobalVariable(name: "ENUM_B", scope: !0, file: !1, line: 10, type: !12, isLocal: true, isDefinition: true)
+!27 = !{i32 2, !"CodeView", i32 1}
+!28 = !{i32 2, !"Debug Info Version", i32 3}
+!29 = !{i32 1, !"wchar_size", i32 2}
+!30 = !{i32 7, !"PIC Level", i32 2}
+!31 = !{!"clang version 9.0.0 (https://github.com/llvm/llvm-project.git f60f863075c7056f26e701b0405fc5752f0db576)"}
+!32 = distinct !DISubprogram(name: "useConst", linkageName: "?useConst@@YAXH@Z", scope: !1, file: !1, line: 12, type: !33, scopeLine: 12, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !35)
+!33 = !DISubroutineType(types: !34)
+!34 = !{null, !9}
+!35 = !{}
+!36 = !DILocalVariable(arg: 1, scope: !32, file: !1, line: 12, type: !9)
+!37 = !DILocation(line: 12, scope: !32)
+!38 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 13, type: !39, scopeLine: 13, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !35)
+!39 = !DISubroutineType(types: !40)
+!40 = !{!9}
+!41 = !DILocation(line: 14, scope: !38)
+!42 = !DILocation(line: 15, scope: !38)
+!43 = !DILocation(line: 16, scope: !38)
+!44 = !DILocation(line: 17, scope: !38)
+!45 = !DILocation(line: 18, scope: !38)
+!46 = !DILocation(line: 19, scope: !38)