IR: Handle self-referencing DICompositeTypes in DIBuilder
Add API to DIBuilder to handle self-referencing `DICompositeType`s.
Self-references aren't expected in the debug info graph, and we take
advantage of that by only calling `resolveCycles()` on nodes that were
once forward declarations (otherwise, DIBuilder needs an expensive
tracking reference to every unresolved node it creates, which in cyclic
graphs is *all of them*).
However, clang seems to create self-referencing `DICompositeType`s. Add
API to manage this safely. The paired commit to clang will include the
regression test.
I'll make the `DICompositeType` API `private` in a follow-up to prevent
misuse (I've separated that to prevent build failures from missing the
clang commit).
llvm-svn: 224482
diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index ee7e6a2..1874d31 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -1205,3 +1205,35 @@
MetadataAsValue::get(VMContext, Expr)};
return CallInst::Create(ValueFn, Args, "", InsertAtEnd);
}
+
+void DIBuilder::replaceVTableHolder(DICompositeType &T, DICompositeType VTableHolder) {
+ T.setContainingType(VTableHolder);
+
+ // If this didn't create a self-reference, just return.
+ if (T != VTableHolder)
+ return;
+
+ // Look for unresolved operands. T has dropped RAUW support and is already
+ // marked resolved, orphaning any cycles underneath it.
+ assert(T->isResolved() && "Expected self-reference to be resolved");
+ for (const MDOperand &O : T->operands())
+ if (auto *N = dyn_cast_or_null<MDNode>(O))
+ trackIfUnresolved(N);
+}
+
+void DIBuilder::replaceArrays(DICompositeType &T, DIArray Elements,
+ DIArray TParams) {
+ T.setArrays(Elements, TParams);
+
+ // If T isn't resolved, there's no problem.
+ if (!T->isResolved())
+ return;
+
+ // If "T" is resolved, it may be due to a self-reference cycle. Track the
+ // arrays explicitly if they're unresolved, or else the cycles will be
+ // orphaned.
+ if (Elements)
+ trackIfUnresolved(Elements);
+ if (TParams)
+ trackIfUnresolved(TParams);
+}