[codeview] support emitting indirect virtual base class information

[inglorion]

Summary

Fixes PR28281.

MSVC lists indirect virtual base classes in the field list of a class,
using LF_IVBCLASS records. This change makes LLVM emit such records
when processing DW_TAG_inheritance tags with the DIFlagVirtual and
(newly introduced) DIFlagIndirect tags.

[rnk]

include/llvm/DebugInfo/CodeView/TypeRecord.h

1201–1202

Can you remove this ctor? We appear to use the wrong kind in VirtualBaseClassRecord::deserialize.

include/llvm/IR/DebugInfoFlags.def

44

@aprantl, should we sorry about running out of these bits now? We only want to use this flag with DW_TAG_inheritance types, so we could do something like reuse the StaticMember flag. We can still introduce a new name, and maybe make it hyper-specific, like IndirectVirtualBase.

This is worth thinking about since these flags go into bitcode, and we need to be backwards compatible with that once we release it.

test/DebugInfo/COFF/inheritance.ll

102

Interesting, it looks like something was able to optimize D's initializer when you regenerated the test. Seems fine.

[zturner]

include/llvm/DebugInfo/CodeView/TypeRecord.h

1201–1202

Remove which constructor? deserialize still needs to call this constructor right?

test/DebugInfo/COFF/inheritance.ll

33

What does the {{.*}} syntax mean here?

[inglorion]

include/llvm/DebugInfo/CodeView/TypeRecord.h

1201–1202

I think @rnk wants me to remove the constructor that does not take a Kind parameter, forcing callers to always specify if they want a VirtualBaseClass or an IndirectVirtualBaseClass. Makes sense, and I have updated the code to do that, which I'll send in the next version of this diff.

test/DebugInfo/COFF/inheritance.ll

33

The {{ and }} are used for regular expression matching. So this matches any sequence of characters enclosed by parentheses. It's the same matching we use in other clauses in the same file, where there needs to be something there, but we don't care about the exact value.

[inglorion]

Removed the old VirtualBaseClassRecord constructor, as @rnk suggested.

[rnk]

include/llvm/IR/DebugInfoFlags.def

44

Let's do this. We can reuse the FwdDecl flag as discussed. You can't forward declare a DW_TAG_inheritance node.

[aprantl]

Sorry, I missed this when it came up originally.
Reusing an otherwise not applicable bit seems fine to me.

[inglorion]

Made DIFlagIndirectVirtualBase == DIFlagVirtual | DIFlagFwdDecl, so that we don't need to allocate another bit.

[rnk]

lgtm

Sorry for the delay, I thought I stamped this already.

include/llvm/DebugInfo/CodeView/TypeRecord.h

struct Layout {
     TypeIndex BaseType;     // Base class type
     // BaseOffset: LF_NUMERIC encoded byte offset of base from derived.
   };
 };
 
 // LF_VBCLASS, LF_IVBCLASS
 class VirtualBaseClassRecord : public TypeRecord {
 public:
   explicit VirtualBaseClassRecord(TypeRecordKind Kind) : TypeRecord(Kind) {}
-  VirtualBaseClassRecord(MemberAccess Access, TypeIndex BaseType,
-                         TypeIndex VBPtrType, uint64_t Offset, uint64_t Index)
-      : TypeRecord(TypeRecordKind::VirtualBaseClass), Access(Access),
-        BaseType(BaseType), VBPtrType(VBPtrType), VBPtrOffset(Offset),
-        VTableIndex(Index) {}
+  VirtualBaseClassRecord(TypeRecordKind Kind, MemberAccess Access,
+                         TypeIndex BaseType, TypeIndex VBPtrType,
+                         uint64_t Offset, uint64_t Index)
+      : TypeRecord(Kind), Access(Access), BaseType(BaseType),
+        VBPtrType(VBPtrType), VBPtrOffset(Offset), VTableIndex(Index) {}
 
   /// Rewrite member type indices with IndexMap. Returns false if a type index
   /// is not in the map.
   bool remapTypeIndices(ArrayRef<TypeIndex> IndexMap);
 
   static Expected<VirtualBaseClassRecord>
   deserialize(TypeRecordKind Kind, msf::StreamReader &Reader);
 

include/llvm/IR/DebugInfoFlags.def

 HANDLE_DI_FLAG((1 << 14), RValueReference)
 HANDLE_DI_FLAG((1 << 15), ExternalTypeRef)
 HANDLE_DI_FLAG((1 << 16), SingleInheritance)
 HANDLE_DI_FLAG((2 << 16), MultipleInheritance)
 HANDLE_DI_FLAG((3 << 16), VirtualInheritance)
 HANDLE_DI_FLAG((1 << 18), IntroducedVirtual)
 HANDLE_DI_FLAG((1 << 19), BitField)
 HANDLE_DI_FLAG((1 << 20), NoReturn)
 
+// To avoid needing a dedicated value for IndirectVirtualBase, we use
+// the bitwise or of Virtual and FwdDecl, which does not otherwise
+// make sense for inheritance.
+HANDLE_DI_FLAG((1 << 2) | (1 << 5), IndirectVirtualBase)
+
 #ifdef DI_FLAG_LARGEST_NEEDED
 // intended to be used with ADT/BitmaskEnum.h
 // NOTE: always must be equal to largest flag, check this when adding new flag
 HANDLE_DI_FLAG((1 << 20), Largest)
 #undef DI_FLAG_LARGEST_NEEDED
 #endif
 
 #undef HANDLE_DI_FLAG

lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

CodeViewDebug::lowerRecordFieldList(const DICompositeType *Ty) {
   // Create base classes.
   for (const DIDerivedType *I : Info.Inheritance) {
     if (I->getFlags() & DINode::FlagVirtual) {
       // Virtual base.
       // FIXME: Emit VBPtrOffset when the frontend provides it.
       unsigned VBPtrOffset = 0;
       // FIXME: Despite the accessor name, the offset is really in bytes.
       unsigned VBTableIndex = I->getOffsetInBits() / 4;
+      auto RecordKind = (I->getFlags() & DINode::FlagIndirectVirtualBase) == DINode::FlagIndirectVirtualBase
+                            ? TypeRecordKind::IndirectVirtualBaseClass
+                            : TypeRecordKind::VirtualBaseClass;
       Fields.writeMemberType(VirtualBaseClassRecord(
-          translateAccessFlags(Ty->getTag(), I->getFlags()),
+          RecordKind, translateAccessFlags(Ty->getTag(), I->getFlags()),
           getTypeIndex(I->getBaseType()), getVBPTypeIndex(), VBPtrOffset,
           VBTableIndex));
     } else {
       assert(I->getOffsetInBits() % 8 == 0 &&
              "bases must be on byte boundaries");
       Fields.writeMemberType(BaseClassRecord(
           translateAccessFlags(Ty->getTag(), I->getFlags()),
           getTypeIndex(I->getBaseType()), I->getOffsetInBits() / 8));

lib/DebugInfo/CodeView/TypeRecord.cpp

 
 Expected<VirtualBaseClassRecord>
 VirtualBaseClassRecord::deserialize(TypeRecordKind Kind,
                                     msf::StreamReader &Reader) {
   const Layout *L = nullptr;
   uint64_t Offset;
   uint64_t Index;
   CV_DESERIALIZE(Reader, L, CV_NUMERIC_FIELD(Offset), CV_NUMERIC_FIELD(Index));
-  return VirtualBaseClassRecord(L->Attrs.getAccess(), L->BaseType, L->VBPtrType,
-                                Offset, Index);
+  return VirtualBaseClassRecord(Kind, L->Attrs.getAccess(), L->BaseType,
+                                L->VBPtrType, Offset, Index);
 }
 
 Expected<ListContinuationRecord>
 ListContinuationRecord::deserialize(TypeRecordKind Kind,
                                     msf::StreamReader &Reader) {
   const Layout *L = nullptr;
   CV_DESERIALIZE(Reader, L);
   return ListContinuationRecord(L->ContinuationIndex);

lib/IR/DebugInfoMetadata.cpp

case Flag##NAME:                                                             \
     return "DIFlag" #NAME;
 #include "llvm/IR/DebugInfoFlags.def"
   }
   return "";
 }
 
 DINode::DIFlags DINode::splitFlags(DIFlags Flags,
                                    SmallVectorImpl<DIFlags> &SplitFlags) {
-  // Accessibility and member pointer flags need to be specially handled, since
-  // they're packed together.
+  // Flags that are packed together need to be specially handled, so
+  // that, for example, we emit "DIFlagPublic" and not
+  // "DIFlagPrivate | DIFlagProtected".
   if (DIFlags A = Flags & FlagAccessibility) {
     if (A == FlagPrivate)
       SplitFlags.push_back(FlagPrivate);
     else if (A == FlagProtected)
       SplitFlags.push_back(FlagProtected);
     else
       SplitFlags.push_back(FlagPublic);
     Flags &= ~A;
   }
   if (DIFlags R = Flags & FlagPtrToMemberRep) {
     if (R == FlagSingleInheritance)
       SplitFlags.push_back(FlagSingleInheritance);
     else if (R == FlagMultipleInheritance)
       SplitFlags.push_back(FlagMultipleInheritance);
     else
       SplitFlags.push_back(FlagVirtualInheritance);
     Flags &= ~R;
   }
+  if ((Flags & FlagIndirectVirtualBase) == FlagIndirectVirtualBase) {
+    Flags &= ~FlagIndirectVirtualBase;
+    SplitFlags.push_back(FlagIndirectVirtualBase);
+  }
 
 #define HANDLE_DI_FLAG(ID, NAME)                                               \
   if (DIFlags Bit = Flags & Flag##NAME) {                                      \
     SplitFlags.push_back(Bit);                                                 \
     Flags &= ~Bit;                                                             \
   }
 #include "llvm/IR/DebugInfoFlags.def"
   return Flags;

test/DebugInfo/COFF/inheritance.ll

 ; CHECK-NEXT:       BaseOffset: 0x8
 ; CHECK-NEXT:     }
 ; CHECK-NEXT:     BaseClass {
 ; CHECK-NEXT:       TypeLeafKind: LF_BCLASS (0x1400)
 ; CHECK-NEXT:       AccessSpecifier: Public (0x3)
 ; CHECK-NEXT:       BaseType: C ({{.*}})
 ; CHECK-NEXT:       BaseOffset: 0x18
 ; CHECK-NEXT:     }
+; CHECK-NEXT:     IndirectVirtualBaseClass {
+; CHECK-NEXT:       TypeLeafKind: LF_IVBCLASS (0x1402)
+; CHECK-NEXT:       AccessSpecifier: Public (0x3)
+; CHECK-NEXT:       BaseType: A ({{.*}})
+; CHECK-NEXT:       VBPtrType: const int* ({{.*}})
+; CHECK-NEXT:       VBPtrOffset: 0x0
+; CHECK-NEXT:       VBTableIndex: 0x1
+; CHECK-NEXT:     }
 ; CHECK:        }
 
 ; Then B's field list.
 ; CHECK:        FieldList ({{.*}}) {
 ; CHECK-NEXT:     TypeLeafKind: LF_FIELDLIST (0x1203)
 ; CHECK-NEXT:     VirtualBaseClass {
 ; CHECK-NEXT:       TypeLeafKind: LF_VBCLASS (0x1401)
 ; CHECK-NEXT:       AccessSpecifier: Public (0x3)

 source_filename = "t.cpp"
 target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-windows-msvc19.0.23918"
 
 %struct.D = type { i32 (...)**, %struct.B.base, %struct.C.base, i32, [4 x i8], %struct.A }
 %struct.B.base = type { i32*, i32 }
 %struct.C.base = type { i32*, i32 }
 %struct.A = type { i32 }
-%struct.B = type { i32*, i32, [4 x i8], %struct.A }
-%struct.C = type { i32*, i32, [4 x i8], %struct.A }
-
-$"\01??0D@@QEAA@XZ" = comdat any
-
-$"\01??0B@@QEAA@XZ" = comdat any
-
-$"\01??0C@@QEAA@XZ" = comdat any
 
 $"\01??_8D@@7BB@@@" = comdat any
 
 $"\01??_8D@@7BC@@@" = comdat any
 
 $"\01??_7D@@6B@" = comdat any
 
-$"\01??_8B@@7B@" = comdat any
-
-$"\01??_8C@@7B@" = comdat any
-
-@"\01?d@@3UD@@A" = global %struct.D zeroinitializer, align 8, !dbg !4
+@"\01?d@@3UD@@A" = local_unnamed_addr global %struct.D { i32 (...)** bitcast ([1 x i8*]* @"\01??_7D@@6B@" to i32 (...)**), %struct.B.base { i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8D@@7BB@@@", i32 0, i32 0), i32 0 }, %struct.C.base { i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8D@@7BC@@@", i32 0, i32 0), i32 0 }, i32 0, [4 x i8] zeroinitializer, %struct.A zeroinitializer }, align 8, !dbg !0
 @"\01??_8D@@7BB@@@" = linkonce_odr unnamed_addr constant [2 x i32] [i32 0, i32 40], comdat
 @"\01??_8D@@7BC@@@" = linkonce_odr unnamed_addr constant [2 x i32] [i32 0, i32 24], comdat
 @"\01??_7D@@6B@" = linkonce_odr unnamed_addr constant [1 x i8*] [i8* bitcast (void (%struct.D*)* @"\01?f@D@@UEAAXXZ" to i8*)], comdat
-@"\01??_8B@@7B@" = linkonce_odr unnamed_addr constant [2 x i32] [i32 0, i32 16], comdat
-@"\01??_8C@@7B@" = linkonce_odr unnamed_addr constant [2 x i32] [i32 0, i32 16], comdat
[e-mail]_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_t.cpp, i8* null }]
-
-; Function Attrs: uwtable
-define internal void @"\01??__Ed@@YAXXZ"() #0 !dbg !37 {
-entry:
-  %call = call %struct.D* @"\01??0D@@QEAA@XZ"(%struct.D* @"\01?d@@3UD@@A", i32 1) #4, !dbg !40
-  ret void, !dbg !40
-}
-
-; Function Attrs: inlinehint nounwind uwtable
-define linkonce_odr %struct.D* @"\01??0D@@QEAA@XZ"(%struct.D* returned %this, i32 %is_most_derived) unnamed_addr #1 comdat align 2 !dbg !41 {
-entry:
-  %retval = alloca %struct.D*, align 8
-  %is_most_derived.addr = alloca i32, align 4
-  %this.addr = alloca %struct.D*, align 8
-  store i32 %is_most_derived, i32* %is_most_derived.addr, align 4
-  call void @llvm.dbg.declare(metadata i32* %is_most_derived.addr, metadata !43, metadata !44), !dbg !45
-  store %struct.D* %this, %struct.D** %this.addr, align 8
-  call void @llvm.dbg.declare(metadata %struct.D** %this.addr, metadata !46, metadata !44), !dbg !45
-  %this1 = load %struct.D*, %struct.D** %this.addr, align 8
-  store %struct.D* %this1, %struct.D** %retval, align 8
-  %is_most_derived2 = load i32, i32* %is_most_derived.addr, align 4
-  %is_complete_object = icmp ne i32 %is_most_derived2, 0, !dbg !48
-  br i1 %is_complete_object, label %ctor.init_vbases, label %ctor.skip_vbases, !dbg !48
-
-ctor.init_vbases:                                 ; preds = %entry
-  %this.int8 = bitcast %struct.D* %this1 to i8*, !dbg !48
-  %0 = getelementptr inbounds i8, i8* %this.int8, i64 8, !dbg !48
-  %vbptr.D = bitcast i8* %0 to i32**, !dbg !48
-  store i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8D@@7BB@@@", i32 0, i32 0), i32** %vbptr.D, align 8, !dbg !48
-  %1 = getelementptr inbounds i8, i8* %this.int8, i64 24, !dbg !48
-  %vbptr.C = bitcast i8* %1 to i32**, !dbg !48
-  store i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8D@@7BC@@@", i32 0, i32 0), i32** %vbptr.C, align 8, !dbg !48
-  %2 = bitcast %struct.D* %this1 to i8*, !dbg !48
-  %3 = getelementptr inbounds i8, i8* %2, i64 48, !dbg !48
-  %4 = bitcast i8* %3 to %struct.A*, !dbg !48
-  br label %ctor.skip_vbases, !dbg !48
-
-ctor.skip_vbases:                                 ; preds = %ctor.init_vbases, %entry
-  %5 = bitcast %struct.D* %this1 to i8*, !dbg !48
-  %6 = getelementptr inbounds i8, i8* %5, i64 8, !dbg !48
-  %7 = bitcast i8* %6 to %struct.B*, !dbg !48
-  %call = call %struct.B* @"\01??0B@@QEAA@XZ"(%struct.B* %7, i32 0) #4, !dbg !48
-  %8 = bitcast %struct.D* %this1 to i8*, !dbg !48
-  %9 = getelementptr inbounds i8, i8* %8, i64 24, !dbg !48
-  %10 = bitcast i8* %9 to %struct.C*, !dbg !48
-  %call3 = call %struct.C* @"\01??0C@@QEAA@XZ"(%struct.C* %10, i32 0) #4, !dbg !48
-  %11 = bitcast %struct.D* %this1 to i32 (...)***, !dbg !48
-  store i32 (...)** bitcast ([1 x i8*]* @"\01??_7D@@6B@" to i32 (...)**), i32 (...)*** %11, align 8, !dbg !48
-  %12 = load %struct.D*, %struct.D** %retval, align 8, !dbg !48
-  ret %struct.D* %12, !dbg !48
-}
-
-; Function Attrs: nounwind readnone
-declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
-
-; Function Attrs: inlinehint nounwind uwtable
-define linkonce_odr %struct.B* @"\01??0B@@QEAA@XZ"(%struct.B* returned %this, i32 %is_most_derived) unnamed_addr #1 comdat align 2 !dbg !49 {
-entry:
-  %retval = alloca %struct.B*, align 8
-  %is_most_derived.addr = alloca i32, align 4
-  %this.addr = alloca %struct.B*, align 8
-  store i32 %is_most_derived, i32* %is_most_derived.addr, align 4
-  call void @llvm.dbg.declare(metadata i32* %is_most_derived.addr, metadata !54, metadata !44), !dbg !55
-  store %struct.B* %this, %struct.B** %this.addr, align 8
-  call void @llvm.dbg.declare(metadata %struct.B** %this.addr, metadata !56, metadata !44), !dbg !55
-  %this1 = load %struct.B*, %struct.B** %this.addr, align 8
-  store %struct.B* %this1, %struct.B** %retval, align 8
-  %is_most_derived2 = load i32, i32* %is_most_derived.addr, align 4
-  %is_complete_object = icmp ne i32 %is_most_derived2, 0, !dbg !58
-  br i1 %is_complete_object, label %ctor.init_vbases, label %ctor.skip_vbases, !dbg !58
-
-ctor.init_vbases:                                 ; preds = %entry
-  %this.int8 = bitcast %struct.B* %this1 to i8*, !dbg !58
-  %0 = getelementptr inbounds i8, i8* %this.int8, i64 0, !dbg !58
-  %vbptr.B = bitcast i8* %0 to i32**, !dbg !58
-  store i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8B@@7B@", i32 0, i32 0), i32** %vbptr.B, align 8, !dbg !58
-  %1 = bitcast %struct.B* %this1 to i8*, !dbg !58
-  %2 = getelementptr inbounds i8, i8* %1, i64 16, !dbg !58
-  %3 = bitcast i8* %2 to %struct.A*, !dbg !58
-  br label %ctor.skip_vbases, !dbg !58
-
-ctor.skip_vbases:                                 ; preds = %ctor.init_vbases, %entry
-  %4 = load %struct.B*, %struct.B** %retval, align 8, !dbg !58
-  ret %struct.B* %4, !dbg !58
-}
-
-; Function Attrs: inlinehint nounwind uwtable
-define linkonce_odr %struct.C* @"\01??0C@@QEAA@XZ"(%struct.C* returned %this, i32 %is_most_derived) unnamed_addr #1 comdat align 2 !dbg !59 {
-entry:
-  %retval = alloca %struct.C*, align 8
-  %is_most_derived.addr = alloca i32, align 4
-  %this.addr = alloca %struct.C*, align 8
-  store i32 %is_most_derived, i32* %is_most_derived.addr, align 4
-  call void @llvm.dbg.declare(metadata i32* %is_most_derived.addr, metadata !64, metadata !44), !dbg !65
-  store %struct.C* %this, %struct.C** %this.addr, align 8
-  call void @llvm.dbg.declare(metadata %struct.C** %this.addr, metadata !66, metadata !44), !dbg !65
-  %this1 = load %struct.C*, %struct.C** %this.addr, align 8
-  store %struct.C* %this1, %struct.C** %retval, align 8
-  %is_most_derived2 = load i32, i32* %is_most_derived.addr, align 4
-  %is_complete_object = icmp ne i32 %is_most_derived2, 0, !dbg !68
-  br i1 %is_complete_object, label %ctor.init_vbases, label %ctor.skip_vbases, !dbg !68
-
-ctor.init_vbases:                                 ; preds = %entry
-  %this.int8 = bitcast %struct.C* %this1 to i8*, !dbg !68
-  %0 = getelementptr inbounds i8, i8* %this.int8, i64 0, !dbg !68
-  %vbptr.C = bitcast i8* %0 to i32**, !dbg !68
-  store i32* getelementptr inbounds ([2 x i32], [2 x i32]* @"\01??_8C@@7B@", i32 0, i32 0), i32** %vbptr.C, align 8, !dbg !68
-  %1 = bitcast %struct.C* %this1 to i8*, !dbg !68
-  %2 = getelementptr inbounds i8, i8* %1, i64 16, !dbg !68
-  %3 = bitcast i8* %2 to %struct.A*, !dbg !68
-  br label %ctor.skip_vbases, !dbg !68
-
-ctor.skip_vbases:                                 ; preds = %ctor.init_vbases, %entry
-  %4 = load %struct.C*, %struct.C** %retval, align 8, !dbg !68
-  ret %struct.C* %4, !dbg !68
-}
-
-declare void @"\01?f@D@@UEAAXXZ"(%struct.D*) unnamed_addr #3
-
-; Function Attrs: uwtable
-define internal void @_GLOBAL__sub_I_t.cpp() #0 !dbg !69 {
-entry:
-  call void @"\01??__Ed@@YAXXZ"(), !dbg !71
-  ret void
-}
-
-attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
-attributes #1 = { inlinehint nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
-attributes #2 = { nounwind readnone }
-attributes #3 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
-attributes #4 = { nounwind }
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!33, !34, !35}
-!llvm.ident = !{!36}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.9.0 ", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
-!1 = !DIFile(filename: "t.cpp", directory: "D:\5Csrc\5Cllvm\5Cbuild")
-!2 = !{}
-!3 = !{!4}
-!4 = distinct !DIGlobalVariable(name: "d", linkageName: "\01?d@@3UD@@A", scope: !0, file: !1, line: 9, type: !5, isLocal: false, isDefinition: true)
-!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "D", file: !1, line: 4, size: 448, align: 64, elements: !6, vtableHolder: !5, identifier: ".?AUD@@")
-!6 = !{!7, !21, !27, !28, !29}
-!7 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !5, baseType: !8, offset: 64)
-!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "B", file: !1, line: 2, size: 192, align: 64, elements: !9, vtableHolder: !8, identifier: ".?AUB@@")
-!9 = !{!10, !15, !20}
-!10 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !8, baseType: !11, offset: 4, flags: DIFlagVirtual)
-!11 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !1, line: 1, size: 32, align: 32, elements: !12, identifier: ".?AUA@@")
-!12 = !{!13}
-!13 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !11, file: !1, line: 1, baseType: !14, size: 32, align: 32)
-!14 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
-!15 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$B", scope: !1, file: !1, baseType: !16, size: 64, flags: DIFlagArtificial)
-!16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !17, size: 64)
-!17 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: !18, size: 64)
-!18 = !DISubroutineType(types: !19)
-!19 = !{!14}
-!20 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !8, file: !1, line: 2, baseType: !14, size: 32, align: 32, offset: 64)
-!21 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !5, baseType: !22, offset: 192)
-!22 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "C", file: !1, line: 3, size: 192, align: 64, elements: !23, vtableHolder: !22, identifier: ".?AUC@@")
-!23 = !{!24, !25, !26}
-!24 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !22, baseType: !11, offset: 4, flags: DIFlagVirtual)
-!25 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$C", scope: !1, file: !1, baseType: !16, size: 64, flags: DIFlagArtificial)
-!26 = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: !22, file: !1, line: 3, baseType: !14, size: 32, align: 32, offset: 64)
-!27 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$D", scope: !1, file: !1, baseType: !16, size: 64, flags: DIFlagArtificial)
-!28 = !DIDerivedType(tag: DW_TAG_member, name: "d", scope: !5, file: !1, line: 6, baseType: !14, size: 32, align: 32, offset: 320)
-!29 = !DISubprogram(name: "f", linkageName: "\01?f@D@@UEAAXXZ", scope: !5, file: !1, line: 5, type: !30, isLocal: false, isDefinition: false, scopeLine: 5, containingType: !5, virtuality: DW_VIRTUALITY_virtual, virtualIndex: 0, flags: DIFlagPrototyped | DIFlagIntroducedVirtual, isOptimized: false)
-!30 = !DISubroutineType(types: !31)
-!31 = !{null, !32}
-!32 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
-!33 = !{i32 2, !"CodeView", i32 1}
-!34 = !{i32 2, !"Debug Info Version", i32 3}
-!35 = !{i32 1, !"PIC Level", i32 2}
-!36 = !{!"clang version 3.9.0 "}
-!37 = distinct !DISubprogram(name: "??__Ed@@YAXXZ", scope: !1, file: !1, line: 9, type: !38, isLocal: true, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
-!38 = !DISubroutineType(types: !39)
-!39 = !{null}
-!40 = !DILocation(line: 9, column: 3, scope: !37)
-!41 = distinct !DISubprogram(name: "D", linkageName: "\01??0D@@QEAA@XZ", scope: !5, file: !1, line: 4, type: !30, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !0, declaration: !42, variables: !2)
-!42 = !DISubprogram(name: "D", scope: !5, type: !30, isLocal: false, isDefinition: false, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false)
-!43 = !DILocalVariable(name: "is_most_derived", arg: 2, scope: !41, type: !14, flags: DIFlagArtificial)
-!44 = !DIExpression()
-!45 = !DILocation(line: 0, scope: !41)
-!46 = !DILocalVariable(name: "this", arg: 1, scope: !41, type: !47, flags: DIFlagArtificial | DIFlagObjectPointer)
-!47 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64, align: 64)
-!48 = !DILocation(line: 4, column: 8, scope: !41)
-!49 = distinct !DISubprogram(name: "B", linkageName: "\01??0B@@QEAA@XZ", scope: !8, file: !1, line: 2, type: !50, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !0, declaration: !53, variables: !2)
-!50 = !DISubroutineType(types: !51)
-!51 = !{null, !52}
-!52 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
-!53 = !DISubprogram(name: "B", scope: !8, type: !50, isLocal: false, isDefinition: false, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false)
-!54 = !DILocalVariable(name: "is_most_derived", arg: 2, scope: !49, type: !14, flags: DIFlagArtificial)
-!55 = !DILocation(line: 0, scope: !49)
-!56 = !DILocalVariable(name: "this", arg: 1, scope: !49, type: !57, flags: DIFlagArtificial | DIFlagObjectPointer)
-!57 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64, align: 64)
-!58 = !DILocation(line: 2, column: 8, scope: !49)
-!59 = distinct !DISubprogram(name: "C", linkageName: "\01??0C@@QEAA@XZ", scope: !22, file: !1, line: 3, type: !60, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !0, declaration: !63, variables: !2)
-!60 = !DISubroutineType(types: !61)
-!61 = !{null, !62}
-!62 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !22, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
-!63 = !DISubprogram(name: "C", scope: !22, type: !60, isLocal: false, isDefinition: false, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false)
-!64 = !DILocalVariable(name: "is_most_derived", arg: 2, scope: !59, type: !14, flags: DIFlagArtificial)
-!65 = !DILocation(line: 0, scope: !59)
-!66 = !DILocalVariable(name: "this", arg: 1, scope: !59, type: !67, flags: DIFlagArtificial | DIFlagObjectPointer)
-!67 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !22, size: 64, align: 64)
-!68 = !DILocation(line: 3, column: 8, scope: !59)
-!69 = distinct !DISubprogram(linkageName: "_GLOBAL__sub_I_t.cpp", scope: !1, file: !1, type: !70, isLocal: true, isDefinition: true, flags: DIFlagArtificial, isOptimized: false, unit: !0, variables: !2)
-!70 = !DISubroutineType(types: !2)
-!71 = !DILocation(line: 0, scope: !69)
[e-mail]_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer
+
+declare void @"\01?f@D@@UEAAXXZ"(%struct.D*) unnamed_addr #0
+
+attributes #0 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="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"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!1}
+!llvm.module.flags = !{!31, !32, !33}
+!llvm.ident = !{!34}
+
+!0 = distinct !DIGlobalVariable(name: "d", linkageName: "\01?d@@3UD@@A", scope: !1, file: !5, line: 8, type: !6, isLocal: false, isDefinition: true)
+!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "clang version 4.0.0 (http://llvm.org/git/clang.git 95626d54d6db7e13087089396a80ebaccc4ffe7c) (http://llvm.org/git/llvm.git 374b6e2fa0b230d13c0fb9ee7af69b2146bfad8a)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3, globals: !4)
+!2 = !DIFile(filename: "t.cpp", directory: "D:\5Csrc\5Cllvm\5Cbuild")
+!3 = !{}
+!4 = !{!0}
+!5 = !DIFile(filename: "t.cpp", directory: "C:\5Cbuild\5Cllvm\5Cbuild")
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "D", file: !5, line: 4, size: 448, elements: !7, vtableHolder: !6, identifier: ".?AUD@@")
+!7 = !{!8, !17, !22, !23, !24, !26, !27}
+!8 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !6, baseType: !9, offset: 64)
+!9 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "B", file: !5, line: 2, size: 192, elements: !10, vtableHolder: !9, identifier: ".?AUB@@")
+!10 = !{!11, !16}
+!11 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !9, baseType: !12, offset: 4, flags: DIFlagVirtual)
+!12 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !5, line: 1, size: 32, elements: !13, identifier: ".?AUA@@")
+!13 = !{!14}
+!14 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !12, file: !5, line: 1, baseType: !15, size: 32)
+!15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !9, file: !5, line: 2, baseType: !15, size: 32, offset: 64)
+!17 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !6, baseType: !18, offset: 192)
+!18 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "C", file: !5, line: 3, size: 192, elements: !19, vtableHolder: !18, identifier: ".?AUC@@")
+!19 = !{!20, !21}
+!20 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !18, baseType: !12, offset: 4, flags: DIFlagVirtual)
+!21 = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: !18, file: !5, line: 3, baseType: !15, size: 32, offset: 64)
+!22 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !6, baseType: !12, offset: 4, flags: DIFlagIndirectVirtualBase)
+!23 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: null, size: 64)
+!24 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$D", scope: !5, file: !5, baseType: !25, size: 64, flags: DIFlagArtificial)
+!25 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !23, size: 64)
+!26 = !DIDerivedType(tag: DW_TAG_member, name: "d", scope: !6, file: !5, line: 6, baseType: !15, size: 32, offset: 320)
+!27 = !DISubprogram(name: "f", linkageName: "\01?f@D@@UEAAXXZ", scope: !6, file: !5, line: 5, type: !28, isLocal: false, isDefinition: false, scopeLine: 5, containingType: !6, virtuality: DW_VIRTUALITY_virtual, virtualIndex: 0, flags: DIFlagPrototyped | DIFlagIntroducedVirtual, isOptimized: true)
+!28 = !DISubroutineType(types: !29)
+!29 = !{null, !30}
+!30 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !6, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!31 = !{i32 2, !"CodeView", i32 1}
+!32 = !{i32 2, !"Debug Info Version", i32 3}
+!33 = !{i32 1, !"PIC Level", i32 2}
+!34 = !{!"clang version 4.0.0 (http://llvm.org/git/clang.git 95626d54d6db7e13087089396a80ebaccc4ffe7c) (http://llvm.org/git/llvm.git 374b6e2fa0b230d13c0fb9ee7af69b2146bfad8a)"}