[codeview] Don't assert if the array element type is incomplete

This can happen when the frontend knows the debug info will be emitted
somewhere else. Usually this happens for dynamic classes with out of
line constructors or key functions, but it can also happen when modules
are enabled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281060 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

@@ -994,20 +994,25 @@ TypeIndex CodeViewDebug::lowerTypeArray(const DICompositeType *Ty) {
 
   uint64_t ElementSize = getBaseTypeSize(ElementTypeRef) / 8;
 
-  bool UndefinedSubrange = false;
 
-  // FIXME:
-  // There is a bug in the front-end where an array of a structure, which was
-  // declared as incomplete structure first, ends up not getting a size assigned
-  // to it. (PR28303)
+  // We want to assert that the element type multiplied by the array lengths
+  // match the size of the overall array. However, if we don't have complete
+  // type information for the base type, we can't make this assertion. This
+  // happens if limited debug info is enabled in this case:
+  //   struct VTableOptzn { VTableOptzn(); virtual ~VTableOptzn(); };
+  //   VTableOptzn array[3];
+  // The DICompositeType of VTableOptzn will have size zero, and the array will
+  // have size 3 * sizeof(void*), and we should avoid asserting.
+  //
+  // There is a related bug in the front-end where an array of a structure,
+  // which was declared as incomplete structure first, ends up not getting a
+  // size assigned to it. (PR28303)
   // Example:
   //   struct A(*p)[3];
   //   struct A { int f; } a[3];
-  //
-  // This needs to be fixed in the front-end, but in the meantime we don't want
-  // to trigger an assertion because of this.
-  if (Ty->getSizeInBits() == 0) {
-    UndefinedSubrange = true;
+  bool PartiallyIncomplete = false;
+  if (Ty->getSizeInBits() == 0 || ElementSize == 0) {
+    PartiallyIncomplete = true;
   }
 
   // Add subranges to array type.
@@ -1026,18 +1031,24 @@ TypeIndex CodeViewDebug::lowerTypeArray(const DICompositeType *Ty) {
     // FIXME: Make front-end support VLA subrange and emit LF_DIMVARLU.
     if (Count == -1) {
       Count = 1;
-      UndefinedSubrange = true;
+      PartiallyIncomplete = true;
     }
 
-    StringRef Name = (i == 0) ? Ty->getName() : "";
     // Update the element size and element type index for subsequent subranges.
     ElementSize *= Count;
+
+    // If this is the outermost array, use the size from the array. It will be
+    // more accurate if PartiallyIncomplete is true.
+    uint64_t ArraySize =
+        (i == 0 && ElementSize == 0) ? Ty->getSizeInBits() / 8 : ElementSize;
+
+    StringRef Name = (i == 0) ? Ty->getName() : "";
     ElementTypeIndex = TypeTable.writeKnownType(
-        ArrayRecord(ElementTypeIndex, IndexType, ElementSize, Name));
+        ArrayRecord(ElementTypeIndex, IndexType, ArraySize, Name));
   }
 
-  (void)UndefinedSubrange;
-  assert(UndefinedSubrange || ElementSize == (Ty->getSizeInBits() / 8));
+  (void)PartiallyIncomplete;
+  assert(PartiallyIncomplete || ElementSize == (Ty->getSizeInBits() / 8));
 
   return ElementTypeIndex;
 }

test/DebugInfo/COFF/vtable-optzn-array.ll

@@ -0,0 +1,140 @@
+; RUN: llc < %s -filetype=obj -o - | llvm-readobj - -codeview | FileCheck %s
+
+; We used to crash on this input because UnicodeString is a forward declaration
+; with no size. Our array type logic wanted to assert the size of the elements
+; times the length matched the overall size.
+
+; C++ source to regenerate:
+; struct UnicodeString;
+; struct GetFwdDecl {
+;   static UnicodeString format;
+; };
+; GetFwdDecl force_fwd_decl;
+; struct UnicodeString {
+; private:
+;   virtual ~UnicodeString();
+; };
+; struct UseCompleteType {
+;   UseCompleteType();
+;   ~UseCompleteType();
+;   UnicodeString currencySpcAfterSym[1];
+; };
+; UseCompleteType require_complete;
+
+; CHECK:      Array ({{.*}}) {
+; CHECK-NEXT:   TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK-NEXT:   ElementType: UnicodeString
+; CHECK-NEXT:   IndexType: unsigned __int64 (0x23)
+; CHECK-NEXT:   SizeOf: 8
+; CHECK-NEXT:   Name:
+; CHECK-NEXT: }
+
+; 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-pc-windows-msvc"
+
+%struct.GetFwdDecl = type { i8 }
+%struct.UseCompleteType = type { [1 x %struct.UnicodeString] }
+%struct.UnicodeString = type { i32 (...)** }
+
+$"\01??_DUseCompleteType@@QEAA@XZ" = comdat any
+
+@"\01?force_fwd_decl@@3UGetFwdDecl@@A" = global %struct.GetFwdDecl zeroinitializer, align 1
+@"\01?require_complete@@3UUseCompleteType@@A" = global %struct.UseCompleteType zeroinitializer, align 8
+@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_t.cpp, i8* null }]
+
+; Function Attrs: nounwind
+define internal void @"\01??__Erequire_complete@@YAXXZ"() #0 !dbg !25 {
+entry:
+  %call = call %struct.UseCompleteType* @"\01??0UseCompleteType@@QEAA@XZ"(%struct.UseCompleteType* @"\01?require_complete@@3UUseCompleteType@@A"), !dbg !28
+  %0 = call i32 @atexit(void ()* @"\01??__Frequire_complete@@YAXXZ") #2, !dbg !28
+  ret void, !dbg !28
+}
+
+declare %struct.UseCompleteType* @"\01??0UseCompleteType@@QEAA@XZ"(%struct.UseCompleteType* returned) unnamed_addr #1
+
+; Function Attrs: nounwind
+define linkonce_odr void @"\01??_DUseCompleteType@@QEAA@XZ"(%struct.UseCompleteType* %this) unnamed_addr #0 comdat align 2 !dbg !29 {
+entry:
+  %this.addr = alloca %struct.UseCompleteType*, align 8
+  store %struct.UseCompleteType* %this, %struct.UseCompleteType** %this.addr, align 8
+  call void @llvm.dbg.declare(metadata %struct.UseCompleteType** %this.addr, metadata !30, metadata !32), !dbg !33
+  %this1 = load %struct.UseCompleteType*, %struct.UseCompleteType** %this.addr, align 8
+  call void @"\01??1UseCompleteType@@QEAA@XZ"(%struct.UseCompleteType* %this1), !dbg !34
+  ret void, !dbg !34
+}
+
+; Function Attrs: nounwind
+define internal void @"\01??__Frequire_complete@@YAXXZ"() #0 !dbg !35 {
+entry:
+  call void @"\01??_DUseCompleteType@@QEAA@XZ"(%struct.UseCompleteType* @"\01?require_complete@@3UUseCompleteType@@A"), !dbg !36
+  ret void, !dbg !37
+}
+
+; Function Attrs: nounwind
+declare i32 @atexit(void ()*) #2
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #3
+
+declare void @"\01??1UseCompleteType@@QEAA@XZ"(%struct.UseCompleteType*) unnamed_addr #1
+
+; Function Attrs: nounwind
+define internal void @_GLOBAL__sub_I_t.cpp() #0 !dbg !39 {
+entry:
+  call void @"\01??__Erequire_complete@@YAXXZ"(), !dbg !41
+  ret void
+}
+
+attributes #0 = { nounwind "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-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "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-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind }
+attributes #3 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!22, !23}
+!llvm.ident = !{!24}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0 (trunk 281056) (llvm/trunk 281051)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
+!1 = !DIFile(filename: "<stdin>", directory: "C:\5Csrc\5Cllvm\5Cbuild")
+!2 = !{}
+!3 = !{!4, !10}
+!4 = distinct !DIGlobalVariable(name: "force_fwd_decl", linkageName: "\01?force_fwd_decl@@3UGetFwdDecl@@A", scope: !0, file: !5, line: 5, type: !6, isLocal: false, isDefinition: true, variable: %struct.GetFwdDecl* @"\01?force_fwd_decl@@3UGetFwdDecl@@A")
+!5 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Cllvm\5Cbuild")
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "GetFwdDecl", file: !5, line: 2, size: 8, align: 8, elements: !7, identifier: ".?AUGetFwdDecl@@")
+!7 = !{!8}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "format", scope: !6, file: !5, line: 3, baseType: !9, flags: DIFlagStaticMember)
+!9 = !DICompositeType(tag: DW_TAG_structure_type, name: "UnicodeString", file: !5, line: 1, flags: DIFlagFwdDecl, identifier: ".?AUUnicodeString@@")
+!10 = distinct !DIGlobalVariable(name: "require_complete", linkageName: "\01?require_complete@@3UUseCompleteType@@A", scope: !0, file: !5, line: 15, type: !11, isLocal: false, isDefinition: true, variable: %struct.UseCompleteType* @"\01?require_complete@@3UUseCompleteType@@A")
+!11 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "UseCompleteType", file: !5, line: 10, size: 64, align: 64, elements: !12, identifier: ".?AUUseCompleteType@@")
+!12 = !{!13, !17, !21}
+!13 = !DIDerivedType(tag: DW_TAG_member, name: "currencySpcAfterSym", scope: !11, file: !5, line: 13, baseType: !14, size: 64, align: 64)
+!14 = !DICompositeType(tag: DW_TAG_array_type, baseType: !9, size: 64, align: 64, elements: !15)
+!15 = !{!16}
+!16 = !DISubrange(count: 1)
+!17 = !DISubprogram(name: "UseCompleteType", scope: !11, file: !5, line: 11, type: !18, isLocal: false, isDefinition: false, scopeLine: 11, flags: DIFlagPrototyped, isOptimized: false)
+!18 = !DISubroutineType(types: !19)
+!19 = !{null, !20}
+!20 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!21 = !DISubprogram(name: "~UseCompleteType", scope: !11, file: !5, line: 12, type: !18, isLocal: false, isDefinition: false, scopeLine: 12, flags: DIFlagPrototyped, isOptimized: false)
+!22 = !{i32 2, !"CodeView", i32 1}
+!23 = !{i32 2, !"Debug Info Version", i32 3}
+!24 = !{!"clang version 4.0.0 (trunk 281056) (llvm/trunk 281051)"}
+!25 = distinct !DISubprogram(name: "??__Erequire_complete@@YAXXZ", scope: !5, file: !5, line: 15, type: !26, isLocal: true, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!26 = !DISubroutineType(types: !27)
+!27 = !{null}
+!28 = !DILocation(line: 15, scope: !25)
+!29 = distinct !DISubprogram(name: "~UseCompleteType", linkageName: "\01??_DUseCompleteType@@QEAA@XZ", scope: !11, file: !5, line: 12, type: !18, isLocal: false, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: false, unit: !0, declaration: !21, variables: !2)
+!30 = !DILocalVariable(name: "this", arg: 1, scope: !29, type: !31, flags: DIFlagArtificial | DIFlagObjectPointer)
+!31 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, align: 64)
+!32 = !DIExpression()
+!33 = !DILocation(line: 0, scope: !29)
+!34 = !DILocation(line: 15, scope: !29)
+!35 = distinct !DISubprogram(name: "??__Frequire_complete@@YAXXZ", scope: !1, file: !1, line: 15, type: !26, isLocal: true, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!36 = !DILocation(line: 15, scope: !35)
+!37 = !DILocation(line: 15, scope: !38)
+!38 = !DILexicalBlockFile(scope: !35, file: !5, discriminator: 0)
+!39 = distinct !DISubprogram(linkageName: "_GLOBAL__sub_I_t.cpp", scope: !1, file: !1, type: !40, isLocal: true, isDefinition: true, flags: DIFlagArtificial, isOptimized: false, unit: !0, variables: !2)
+!40 = !DISubroutineType(types: !2)
+!41 = !DILocation(line: 0, scope: !39)