3 files changed, 89 insertions, 4 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index ed2dfa6906f..6eba00be00e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1277,11 +1277,12 @@ TypeIndex CodeViewDebug::lowerTypeArray(const DICompositeType *Ty) {
            "codeview doesn't support subranges with lower bounds");
     int64_t Count = Subrange->getCount();
 
-    // Variable Length Array (VLA) has Count equal to '-1'.
-    // Replace with Count '1', assume it is the minimum VLA length.
+    // Variable length arrays and forward declarations of arrays without a size
+    // use a count of -1. Emit a count (and overall size) or zero in these cases
+    // to match what MSVC does for array declarations with no count.
     // FIXME: Make front-end support VLA subrange and emit LF_DIMVARLU.
     if (Count == -1)
-      Count = 1;
+      Count = 0;
 
     // Update the element size and element type index for subsequent subranges.
     ElementSize *= Count;
diff --git a/llvm/test/DebugInfo/COFF/types-array-advanced.ll b/llvm/test/DebugInfo/COFF/types-array-advanced.ll
index a2e7c19b74c..f13aa6ac853 100644
--- a/llvm/test/DebugInfo/COFF/types-array-advanced.ll
+++ b/llvm/test/DebugInfo/COFF/types-array-advanced.ll
@@ -47,7 +47,7 @@
 ; CHECK:     TypeLeafKind: LF_ARRAY (0x1503)
 ; CHECK:     ElementType: int (0x74)
 ; CHECK:     IndexType: unsigned long (0x22)
-; CHECK:     SizeOf: 4
+; CHECK:     SizeOf: 0
 ; CHECK:     Name: 
 ; CHECK:   }
 ; CHECK:   Pointer (0x1004) {
diff --git a/llvm/test/DebugInfo/COFF/types-array-unsized.ll b/llvm/test/DebugInfo/COFF/types-array-unsized.ll
new file mode 100644
index 00000000000..694e0a77b2c
--- /dev/null
+++ b/llvm/test/DebugInfo/COFF/types-array-unsized.ll
@@ -0,0 +1,84 @@
+; RUN: llc -filetype=obj < %s | llvm-readobj -codeview | FileCheck %s
+
+; We should emit two array types: one used to describe the static data member,
+; and the other used by the S_GDATA32 for the definition.
+
+; C++ source:
+; struct Foo {
+;   static const char str[];
+; };
+; const char Foo::str[] = "asdf";
+; Foo f; // FIXME: only needed to force emit 'Foo'
+
+; CHECK:      CodeViewTypes [
+; CHECK:        Array ([[ARRAY_COMPLETE:0x.*]]) {
+; CHECK-NEXT:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK-NEXT:     ElementType: const char ({{.*}})
+; CHECK-NEXT:     IndexType: unsigned __int64 (0x23)
+; CHECK-NEXT:     SizeOf: 5
+; CHECK-NEXT:     Name: 
+; CHECK-NEXT:   }
+; CHECK:        Array ([[ARRAY_FWD:0x.*]]) {
+; CHECK-NEXT:     TypeLeafKind: LF_ARRAY (0x1503)
+; CHECK-NEXT:     ElementType: const char ({{.*}})
+; CHECK-NEXT:     IndexType: unsigned __int64 (0x23)
+; CHECK-NEXT:     SizeOf: 0
+; CHECK-NEXT:     Name: 
+; CHECK-NEXT:   }
+; CHECK:        FieldList (0x1004) {
+; CHECK-NEXT:     TypeLeafKind: LF_FIELDLIST (0x1203)
+; CHECK-NEXT:     StaticDataMember {
+; CHECK-NEXT:       TypeLeafKind: LF_STMEMBER (0x150E)
+; CHECK-NEXT:       AccessSpecifier: Public (0x3)
+; CHECK-NEXT:       Type: [[ARRAY_FWD]]
+; CHECK-NEXT:       Name: str
+; CHECK-NEXT:     }
+; CHECK-NEXT:   }
+; CHECK:      ]
+
+; CHECK:          GlobalData {
+; CHECK-NEXT:       Kind: S_GDATA32 (0x110D)
+; CHECK-NEXT:       DataOffset: ?str@Foo@@2QBDB+0x0
+; CHECK-NEXT:       Type: [[ARRAY_COMPLETE]]
+; CHECK-NEXT:       DisplayName: str
+; CHECK-NEXT:       LinkageName: ?str@Foo@@2QBDB
+; 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-msvc19.0.24215"
+
+%struct.Foo = type { i8 }
+
+@"\01?str@Foo@@2QBDB" = constant [5 x i8] c"asdf\00", align 1, !dbg !0
+@"\01?f@@3UFoo@@A" = global %struct.Foo zeroinitializer, align 1, !dbg !6
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!19, !20, !21, !22}
+!llvm.ident = !{!23}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "str", linkageName: "\01?str@Foo@@2QBDB", scope: !2, file: !3, line: 4, type: !16, isLocal: false, isDefinition: true, declaration: !10)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 6.0.0 ", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Cllvm-project\5Cbuild", checksumkind: CSK_MD5, checksum: "15aa843c5a80301928caf03e71f87a54")
+!4 = !{}
+!5 = !{!0, !6}
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "f", linkageName: "\01?f@@3UFoo@@A", scope: !2, file: !3, line: 5, type: !8, isLocal: false, isDefinition: true)
+!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !3, line: 1, size: 8, elements: !9, identifier: ".?AUFoo@@")
+!9 = !{!10}
+!10 = !DIDerivedType(tag: DW_TAG_member, name: "str", scope: !8, file: !3, line: 2, baseType: !11, flags: DIFlagStaticMember)
+!11 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, elements: !14)
+!12 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !13)
+!13 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!14 = !{!15}
+!15 = !DISubrange(count: -1)
+!16 = !DICompositeType(tag: DW_TAG_array_type, baseType: !12, size: 40, elements: !17)
+!17 = !{!18}
+!18 = !DISubrange(count: 5)
+!19 = !{i32 2, !"CodeView", i32 1}
+!20 = !{i32 2, !"Debug Info Version", i32 3}
+!21 = !{i32 1, !"wchar_size", i32 2}
+!22 = !{i32 7, !"PIC Level", i32 2}
+!23 = !{!"clang version 6.0.0 "}