DebugInfo: Only move types out of type units if they're named or type united

Follow up to r359122, after a bug was reported in it - the original
change too aggressively tried to move related types out of type units,
which included unnamed types (like array types) which can't reasonably
be declared-but-not-defined.

A step beyond that is that some types in type units can be anonymous, if
they are types with a name for linkage purposes (eg: "typedef struct { }
x;"). So ensure those don't get turned into plain declarations (without
signatures) because, lacking names, they can't be resolved to the
definition.

[Also include a fix for llvm-dwarfdump/libDebugInfoDWARF to pretty print
types in type units]

llvm-svn: 360458

3 files changed, 15 insertions, 6 deletions

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;
   }