DebugInfo: Remove MDString-based type references

Eliminate DITypeIdentifierMap and make DITypeRef a thin wrapper around
DIType*.  It is no longer legal to refer to a DICompositeType by its
'identifier:', and DIBuilder no longer retains all types with an
'identifier:' automatically.

Aside from the bitcode upgrade, this is mainly removing logic to resolve
an MDString-based reference to an actualy DIType.  The commits leading
up to this have made the implicit type map in DICompileUnit's
'retainedTypes:' field superfluous.

This does not remove DITypeRef, DIScopeRef, DINodeRef, and
DITypeRefArray, or stop using them in DI-related metadata.  Although as
of this commit they aren't serving a useful purpose, there are patchces
under review to reuse them for CodeView support.

The tests in LLVM were updated with deref-typerefs.sh, which is attached
to the thread "[RFC] Lazy-loading of debug info metadata":

  http://lists.llvm.org/pipermail/llvm-dev/2016-April/098318.html

llvm-svn: 267296

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/test/DebugInfo/X86/nodebug_with_debug_loc.ll b/llvm/test/DebugInfo/X86/nodebug_with_debug_loc.ll
index 72255a0aa53..c6d3e64ea01 100644
--- a/llvm/test/DebugInfo/X86/nodebug_with_debug_loc.ll
+++ b/llvm/test/DebugInfo/X86/nodebug_with_debug_loc.ll
@@ -104,7 +104,7 @@ attributes #3 = { nounwind }
 !4 = !DICompositeType(tag: DW_TAG_structure_type, name: "string", line: 7, size: 32, align: 32, file: !5, elements: !6, identifier: "_ZTS6string")
 !5 = !DIFile(filename: "repro.cpp", directory: "/tmp/dbginfo")
 !6 = !{!7}
-!7 = !DIDerivedType(tag: DW_TAG_member, name: "mem", line: 8, size: 32, align: 32, file: !5, scope: !"_ZTS6string", baseType: !8)
+!7 = !DIDerivedType(tag: DW_TAG_member, name: "mem", line: 8, size: 32, align: 32, file: !5, scope: !4, baseType: !8)
 !8 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 32, align: 32, baseType: !9)
 !9 = !DIBasicType(tag: DW_TAG_base_type, name: "unsigned int", size: 32, align: 32, encoding: DW_ATE_unsigned)
 !11 = distinct !DISubprogram(name: "f", linkageName: "_Z1fv", line: 14, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 14, file: !5, scope: !12, type: !13, variables: !15)
@@ -112,11 +112,11 @@ attributes #3 = { nounwind }
 !13 = !DISubroutineType(types: !14)
 !14 = !{null}
 !15 = !{!16}
-!16 = !DILocalVariable(name: "str2", line: 15, scope: !11, file: !12, type: !"_ZTS6string")
+!16 = !DILocalVariable(name: "str2", line: 15, scope: !11, file: !12, type: !4)
 !17 = distinct !DISubprogram(name: "s2", linkageName: "_Z2s2P6string", line: 13, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 13, file: !5, scope: !12, type: !18, variables: !21)
 !18 = !DISubroutineType(types: !19)
 !19 = !{null, !20}
-!20 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 32, align: 32, baseType: !"_ZTS6string")
+!20 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 32, align: 32, baseType: !4)
 !21 = !{!22}
 !22 = !DILocalVariable(name: "lhs", line: 13, arg: 1, scope: !17, file: !12, type: !20)
 !23 = !{i32 2, !"Dwarf Version", i32 4}
@@ -129,7 +129,7 @@ attributes #3 = { nounwind }
 !30 = !DILocation(line: 17, scope: !11)
 !31 = !DILocation(line: 18, scope: !11)
 !32 = !{!33, !34, i64 0}
-!33 = !{!"_ZTS6string", !34, i64 0}
+!33 = !{!4, !34, i64 0}
 !34 = !{!"any pointer", !35, i64 0}
 !35 = !{!"omnipotent char", !36, i64 0}
 !36 = !{!"Simple C/C++ TBAA"}