IR: Use an explicit map for debug info type uniquing
Rather than relying on the structural equivalence of DICompositeType to
merge type definitions, use an explicit map on the LLVMContext that
LLParser and BitcodeReader consult when constructing new nodes.
Each non-forward-declaration DICompositeType with a non-empty
'identifier:' field is stored/loaded from the type map, and the first
definiton will "win".
This map is opt-in: clients that expect ODR types from different modules
to be merged must call LLVMContext::ensureDITypeMap.
- Clients that just happen to load more than one Module in the same
LLVMContext won't magically merge types.
- Clients (like LTO) that want to continue to merge types based on ODR
identifiers should opt-in immediately.
I have updated LTOCodeGenerator.cpp, the two "linking" spots in
gold-plugin.cpp, and llvm-link (unless -disable-debug-info-type-map) to
set this.
With this in place, it will be straightforward to remove the DITypeRef
concept (i.e., referencing types by their 'identifier:' string rather
than pointing at them directly).
llvm-svn: 266549
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index c72b719..34f7ec4 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -3839,11 +3839,25 @@
PARSE_MD_FIELDS();
#undef VISIT_MD_FIELDS
+ // If this isn't a forward declaration and it has a UUID, check for it in the
+ // type map in the context.
+ DIType **MappedT = nullptr;
+ if (!(flags.Val & DINode::FlagFwdDecl) && identifier.Val &&
+ (MappedT = Context.getOrInsertDITypeMapping(*identifier.Val)) &&
+ *MappedT) {
+ Result = *MappedT;
+ return false;
+ }
+
+ // Create a new node, and save it in the context if it belongs in the type
+ // map.
Result = GET_OR_DISTINCT(
DICompositeType,
(Context, tag.Val, name.Val, file.Val, line.Val, scope.Val, baseType.Val,
size.Val, align.Val, offset.Val, flags.Val, elements.Val,
runtimeLang.Val, vtableHolder.Val, templateParams.Val, identifier.Val));
+ if (MappedT)
+ *MappedT = cast<DIType>(Result);
return false;
}