DebugInfo: Add ability to not emit DW_AT_vtable_elem_location for virtual functions.

A virtual index of -1u indicates that the subprogram's virtual index is
unrepresentable (for example, when using the relative vtable ABI), so do
not emit a DW_AT_vtable_elem_location attribute for it.

Differential Revision: http://reviews.llvm.org/D18236

llvm-svn: 263765

1 files changed, 71 insertions, 0 deletions

diff --git a/llvm/test/DebugInfo/Generic/virtual-index.ll b/llvm/test/DebugInfo/Generic/virtual-index.ll
new file mode 100644
index 00000000000..23869f10157
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/virtual-index.ll
@@ -0,0 +1,71 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; Generated from the following C++ source code:
+;
+; struct A {
+;   virtual void f();
+;   virtual void g();
+; };
+;
+; void A::f() {}
+; void A::g() {}
+;
+; and manually edited to set virtualIndex attribute on the A::g subprogram to
+; 4294967295.
+
+; CHECK: DW_TAG_subprogram [
+; CHECK: DW_AT_vtable_elem_location [DW_FORM_exprloc]  (<0x2> 10 00 )
+
+; CHECK: DW_TAG_subprogram [
+; CHECK-NOT: DW_AT_vtable_elem_location
+
+%struct.A = type { i32 (...)** }
+
+@_ZTV1A = unnamed_addr constant [4 x i8*] [i8* null, i8* null, i8* bitcast (void (%struct.A*)* @_ZN1A1fEv to i8*), i8* bitcast (void (%struct.A*)* @_ZN1A1gEv to i8*)], align 8
+
+define void @_ZN1A1fEv(%struct.A* %this) unnamed_addr !dbg !18 {
+  ret void
+}
+
+define void @_ZN1A1gEv(%struct.A* %this) unnamed_addr !dbg !19 {
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!20, !21}
+!llvm.ident = !{!22}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !3, subprograms: !17)
+!1 = !DIFile(filename: "x", directory: "x")
+!2 = !{}
+!3 = !{!4}
+!4 = !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !1, line: 1, size: 64, align: 64, elements: !5, vtableHolder: !"_ZTS1A", identifier: "_ZTS1A")
+!5 = !{!6, !12, !16}
+!6 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$A", scope: !1, file: !1, baseType: !7, size: 64, flags: DIFlagArtificial)
+!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64)
+!8 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: !9, size: 64)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11}
+!11 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!12 = !DISubprogram(name: "f", linkageName: "_ZN1A1fEv", scope: !"_ZTS1A", file: !1, line: 2, type: !13, isLocal: false, isDefinition: false, scopeLine: 2, containingType: !"_ZTS1A", virtuality: DW_VIRTUALITY_virtual, virtualIndex: 0, flags: DIFlagPrototyped, isOptimized: false)
+!13 = !DISubroutineType(types: !14)
+!14 = !{null, !15}
+!15 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!16 = !DISubprogram(name: "g", linkageName: "_ZN1A1gEv", scope: !"_ZTS1A", file: !1, line: 3, type: !13, isLocal: false, isDefinition: false, scopeLine: 3, containingType: !"_ZTS1A", virtuality: DW_VIRTUALITY_virtual, virtualIndex: 4294967295, flags: DIFlagPrototyped, isOptimized: false)
+!17 = !{!18, !19}
+!18 = distinct !DISubprogram(name: "f", linkageName: "_ZN1A1fEv", scope: !"_ZTS1A", file: !1, line: 6, type: !13, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: false, declaration: !12, variables: !2)
+!19 = distinct !DISubprogram(name: "g", linkageName: "_ZN1A1gEv", scope: !"_ZTS1A", file: !1, line: 7, type: !13, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, declaration: !16, variables: !2)
+!20 = !{i32 2, !"Dwarf Version", i32 4}
+!21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !{!"clang version 3.9.0 (trunk 263469) (llvm/trunk 263156)"}
+!23 = !DILocalVariable(name: "this", arg: 1, scope: !18, type: !24, flags: DIFlagArtificial | DIFlagObjectPointer)
+!24 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64)
+!25 = !DIExpression()
+!26 = !DILocation(line: 0, scope: !18)
+!27 = !DILocation(line: 6, column: 14, scope: !18)
+!28 = !DILocalVariable(name: "this", arg: 1, scope: !19, type: !24, flags: DIFlagArtificial | DIFlagObjectPointer)
+!29 = !DILocation(line: 0, scope: !19)
+!30 = !DILocation(line: 7, column: 14, scope: !19)