[PATCH] D41695: [Metadata] Extend 'count' field of DISubrange to take a metadata node

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added a comment.

It looks like this changes the layout of DISubrange from

Flags | Count |



================
Comment at: include/llvm/IR/DebugInfoMetadata.h:372
+
+  ConstantInt *getCount() const {
+    if (auto *MD = dyn_cast<ConstantAsMetadata>(getRawCountNode()))
----------------
Perhaps:
`Optional<ConstantInt *> getConstantCount()` ?


================
Comment at: lib/Bitcode/Writer/BitcodeWriter.cpp:1445
   Record.push_back(N->isDistinct());
-  Record.push_back(N->getCount());
+  Record.push_back(-1); // this field has become obsolete
+  Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
----------------
We typically version bitcode by adding a bit to the flags, like this:
` Record.push_back(N->isDistinct() | 1<<1);`
This way we don't have to waste the space for the obsoleted field.


https://reviews.llvm.org/D41695