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

2 files changed, 35 insertions, 0 deletions

diff --git a/llvm/test/Bitcode/dityperefs-3.8.ll b/llvm/test/Bitcode/dityperefs-3.8.ll
new file mode 100644
index 00000000000..4025f21f0cd
--- /dev/null
+++ b/llvm/test/Bitcode/dityperefs-3.8.ll
@@ -0,0 +1,35 @@
+; RUN: llvm-dis < %s.bc | FileCheck %s
+; RUN: verify-uselistorder %s.bc
+
+; Establish a stable order.
+!named = !{!0, !1, !2, !3, !4, !6, !7, !8, !9, !10, !11, !12}
+
+; CHECK:      !0 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
+; CHECK-NEXT: !1 = !DICompositeType(tag: DW_TAG_structure_type, name: "T1"{{.*}}, identifier: "T1")
+; CHECK-NEXT: !2 = !DICompositeType(tag: DW_TAG_structure_type, name: "T2", scope: !1{{.*}}, baseType: !1, vtableHolder: !1, identifier: "T2")
+; CHECK-NEXT: !3 = !DIDerivedType(tag: DW_TAG_member, name: "M1", scope: !1{{.*}}, baseType: !2)
+; CHECK-NEXT: !4 = !DISubroutineType(types: !5)
+; CHECK-NEXT: !5 = !{!1, !2}
+; CHECK-NEXT: !6 = !DISubprogram(scope: !1,{{.*}} containingType: !1{{[,)]}}
+; CHECK-NEXT: !7 = !DILocalVariable(name: "V1", scope: !6, type: !2)
+; CHECK-NEXT: !8 = !DIObjCProperty(name: "P1", type: !1)
+; CHECK-NEXT: !9 = !DITemplateTypeParameter(type: !1)
+; CHECK-NEXT: !10 = !DIGlobalVariable(name: "G",{{.*}} type: !1,{{.*}} variable: i32* @G1)
+; CHECK-NEXT: !11 = !DITemplateValueParameter(type: !1, value: i32* @G1)
+; CHECK-NEXT: !12 = !DIImportedEntity(tag: DW_TAG_imported_module, name: "T2", scope: !0, entity: !1)
+
+!0 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
+!1 = !DICompositeType(tag: DW_TAG_structure_type, name: "T1", file: !0, identifier: "T1")
+!2 = !DICompositeType(tag: DW_TAG_structure_type, name: "T2", file: !0, scope: !"T1", baseType: !"T1", vtableHolder: !"T1", identifier: "T2")
+!3 = !DIDerivedType(tag: DW_TAG_member, name: "M1", file: !0, scope: !"T1", baseType: !"T2")
+!4 = !DISubroutineType(types: !5)
+!5 = !{!"T1", !"T2"}
+!6 = !DISubprogram(scope: !"T1", isDefinition: false, containingType: !"T1")
+!7 = !DILocalVariable(name: "V1", scope: !6, type: !"T2")
+!8 = !DIObjCProperty(name: "P1", type: !"T1")
+!9 = !DITemplateTypeParameter(type: !"T1")
+!10 = !DIGlobalVariable(name: "G", type: !"T1", isDefinition: false, variable: i32* @G1)
+!11 = !DITemplateValueParameter(type: !"T1", value: i32* @G1)
+!12 = !DIImportedEntity(tag: DW_TAG_imported_module, name: "T2", scope: !0, entity: !"T1")
+
+@G1 = global i32 0
diff --git a/llvm/test/Bitcode/dityperefs-3.8.ll.bc b/llvm/test/Bitcode/dityperefs-3.8.ll.bc
new file mode 100644
index 00000000000..0808389c7c5
--- /dev/null
+++ b/llvm/test/Bitcode/dityperefs-3.8.ll.bc