Debug Info: Add basic support for external types references.

This is a necessary prerequisite for bootstrapping the emission
of debug info inside modules.

- Adds a FlagExternalTypeRef to DICompositeType.
  External types must have a unique identifier.
- External type references are emitted using a forward declaration
  with a DW_AT_signature([DW_FORM_ref_sig8]) based on the UID.

http://reviews.llvm.org/D9612

llvm-svn: 242302

1 files changed, 51 insertions, 0 deletions

diff --git a/llvm/test/DebugInfo/X86/externaltyperef.ll b/llvm/test/DebugInfo/X86/externaltyperef.ll
new file mode 100644
index 00000000000..c344d5f068c
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/externaltyperef.ll
@@ -0,0 +1,51 @@
+; REQUIRES: object-emission
+; RUN: %llc_dwarf -filetype=obj -O0 < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+; Manually derived by externalizing the composite types from:
+;
+;   namespace N { class B; }
+;   using N::B;
+;   class A;
+;   A *a;
+;
+; Test the direct use of an external type.
+; CHECK: DW_TAG_variable
+; CHECK:   DW_AT_type [DW_FORM_ref4]	  {{.*}}{[[PTR:.*]]}
+; CHECK: [[PTR]]: DW_TAG_pointer_type
+; CHECK:   DW_AT_type [DW_FORM_ref4]  	  {{.*}}{[[A:.*]]}
+; CHECK: [[A]]: DW_TAG_class_type
+; CHECK:   DW_AT_declaration [DW_FORM_flag]	(0x01)
+; CHECK:   DW_AT_signature [DW_FORM_ref_sig8]	(0x4e834ea939695c24)
+; CHECK: [[B:.*]]: DW_TAG_class_type
+; CHECK:   DW_AT_declaration [DW_FORM_flag]	(0x01)
+; CHECK:   DW_AT_signature [DW_FORM_ref_sig8]	(0x942e51c7addda5f7)
+; CHECK:   DW_TAG_imported_declaration
+; CHECK:     DW_AT_import [DW_FORM_ref4]  {{.*}}[[B]]
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+%class.A = type opaque
+
+@a = global %class.A* null, align 8
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!13, !14, !15}
+!llvm.ident = !{!16}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.7.0 (trunk 242039) (llvm/trunk 242046)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !3, globals: !5, imports: !11)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{}
+!3 = !{!4, !9}
+!4 = !DICompositeType(tag: DW_TAG_class_type, name: "A", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTS1A")
+!5 = !{!6}
+!6 = !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 2, type: !7, isLocal: false, isDefinition: true, variable: %class.A** @a)
+!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A", size: 64, align: 64)
+!8 = !DICompositeType(tag: DW_TAG_class_type, name: "B", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTS1B")
+!9 = !DICompositeType(tag: DW_TAG_class_type, name: "A", file: !1, flags: DIFlagExternalTypeRef, identifier: "_ZTSN1N1BE")
+!10 = !DINamespace(name: "N", scope: null, file: !1, line: 1)
+!11 = !{!12}
+!12 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !"_ZTSN1N1BE", line: 4)
+!13 = !{i32 2, !"Dwarf Version", i32 2}
+!14 = !{i32 2, !"Debug Info Version", i32 3}
+!15 = !{i32 1, !"PIC Level", i32 2}
+!16 = !{!"clang version 3.7.0 (trunk 242039) (llvm/trunk 242046)"}