5 files changed, 99 insertions, 6 deletions
diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h
index 279a2e7e352..731e71ed9ea 100644
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h
@@ -104,6 +104,11 @@ public:
   /// getAsFoo functions below return the extracted value as Foo if only
   /// DWARFFormValue has form class is suitable for representing Foo.
   Optional<uint64_t> getAsReference() const;
+  struct UnitOffset {
+    DWARFUnit *Unit;
+    uint64_t Offset;
+  };
+  Optional<UnitOffset> getAsRelativeReference() const;
   Optional<uint64_t> getAsUnsignedConstant() const;
   Optional<int64_t> getAsSignedConstant() const;
   Optional<const char *> getAsCString() const;
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 3aa404ed4e9..d9e680846b3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -639,7 +639,8 @@ DIE *DwarfUnit::createTypeDIE(const DIScope *Context, DIE &ContextDIE,
   else if (auto *STy = dyn_cast<DISubroutineType>(Ty))
     constructTypeDIE(TyDIE, STy);
   else if (auto *CTy = dyn_cast<DICompositeType>(Ty)) {
-    if (DD->generateTypeUnits() && !Ty->isForwardDecl()) {
+    if (DD->generateTypeUnits() && !Ty->isForwardDecl() &&
+        (Ty->getRawName() || CTy->getRawIdentifier())) {
       // Skip updating the accelerator tables since this is not the full type.
       if (MDString *TypeId = CTy->getRawIdentifier())
         DD->addDwarfTypeUnitType(getCU(), TypeId->getString(), TyDIE, CTy);
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index 3015ce2e94b..7d80f2eb75b 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -429,9 +429,11 @@ DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
 
 DWARFDie
 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
-  if (auto SpecRef = toReference(V)) {
-    if (auto SpecUnit = U->getUnitVector().getUnitForOffset(*SpecRef))
-      return SpecUnit->getDIEForOffset(*SpecRef);
+  if (auto SpecRef = V.getAsRelativeReference()) {
+    if (SpecRef->Unit)
+      return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
+    if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
+      return SpecUnit->getDIEForOffset(SpecRef->Offset);
   }
   return DWARFDie();
 }
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
index bdc2e54b3e9..8f2524246a8 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -639,6 +639,12 @@ DWARFFormValue::getAsSectionedAddress() const {
 }
 
 Optional<uint64_t> DWARFFormValue::getAsReference() const {
+  if (auto R = getAsRelativeReference())
+    return R->Unit ? R->Unit->getOffset() + R->Offset : R->Offset;
+  return None;
+}
+  
+Optional<DWARFFormValue::UnitOffset> DWARFFormValue::getAsRelativeReference() const {
   if (!isFormClass(FC_Reference))
     return None;
   switch (Form) {
@@ -649,11 +655,11 @@ Optional<uint64_t> DWARFFormValue::getAsReference() const {
   case DW_FORM_ref_udata:
     if (!U)
       return None;
-    return Value.uval + U->getOffset();
+    return UnitOffset{const_cast<DWARFUnit*>(U), Value.uval};
   case DW_FORM_ref_addr:
   case DW_FORM_ref_sig8:
   case DW_FORM_GNU_ref_alt:
-    return Value.uval;
+    return UnitOffset{nullptr, Value.uval};
   default:
     return None;
   }
diff --git a/llvm/test/DebugInfo/X86/tu-to-non-named-type.ll b/llvm/test/DebugInfo/X86/tu-to-non-named-type.ll
new file mode 100644
index 00000000000..556e2adb193
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/tu-to-non-named-type.ll
@@ -0,0 +1,79 @@
+; REQUIRES: object-emission
+
+; RUN: llc -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu < %s \
+; RUN:     | llvm-dwarfdump -debug-info -debug-types - | FileCheck %s
+
+; CHECK: Compile Unit:
+
+; CHECK: Type Unit:
+; CHECK:   DW_TAG_structure
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:     DW_AT_name      ("foo")
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:     DW_TAG_member
+; CHECK-NEXT:       DW_AT_name    ("x")
+; CHECK-NEXT:       DW_AT_type    ({{.*}} "int[1]"
+
+; But make sure we still use a type unit for an anonymous type that still has a
+; name for linkage purposes (due to being defined in a typedef).
+
+; CHECK: Type Unit:
+; CHECK:   DW_TAG_structure
+; CHECK-NEXT:     DW_AT_calling_convention
+; CHECK-NEXT:     DW_AT_byte_size
+; CHECK-NEXT:     DW_AT_decl_file
+; CHECK-NEXT:     DW_AT_decl_line
+; CHECK-NOT: DW
+; CHECK:   NULL
+
+%struct.foo = type { [1 x i32] }
+%struct.bar = type { i8 }
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @_Z1f3foo3bar(i32 %.coerce) #0 !dbg !7 {
+entry:
+  %0 = alloca %struct.foo, align 4
+  %1 = alloca %struct.bar, align 1
+  %coerce.dive = getelementptr inbounds %struct.foo, %struct.foo* %0, i32 0, i32 0
+  %2 = bitcast [1 x i32]* %coerce.dive to i32*
+  store i32 %.coerce, i32* %2, align 4
+  call void @llvm.dbg.declare(metadata %struct.foo* %0, metadata !19, metadata !DIExpression()), !dbg !20
+  call void @llvm.dbg.declare(metadata %struct.bar* %1, metadata !21, metadata !DIExpression()), !dbg !22
+  ret void, !dbg !23
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { noinline nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 9.0.0 (trunk 360374) (llvm/trunk 360380)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "named_types.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 9.0.0 (trunk 360374) (llvm/trunk 360380)"}
+!7 = distinct !DISubprogram(name: "f", linkageName: "_Z1f3foo3bar", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10, !17}
+!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "foo", file: !1, line: 1, size: 32, flags: DIFlagTypePassByValue, elements: !11, identifier: "_ZTS3foo")
+!11 = !{!12}
+!12 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !10, file: !1, line: 2, baseType: !13, size: 32)
+!13 = !DICompositeType(tag: DW_TAG_array_type, baseType: !14, size: 32, elements: !15)
+!14 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!15 = !{!16}
+!16 = !DISubrange(count: 1)
+!17 = !DIDerivedType(tag: DW_TAG_typedef, name: "bar", file: !1, line: 5, baseType: !18)
+!18 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !1, line: 4, size: 8, flags: DIFlagTypePassByValue, elements: !2, identifier: "_ZTS3bar")
+!19 = !DILocalVariable(arg: 1, scope: !7, file: !1, line: 6, type: !10)
+!20 = !DILocation(line: 6, column: 11, scope: !7)
+!21 = !DILocalVariable(arg: 2, scope: !7, file: !1, line: 6, type: !17)
+!22 = !DILocation(line: 6, column: 16, scope: !7)
+!23 = !DILocation(line: 7, column: 1, scope: !7)
+