[PATCH] D83303: [SelectionDAG] Fix incorrect offset when expanding CONCAT_VECTORS.

Tue Jul 7 07:57:28 PDT 2020

cameron.mcinally accepted this revision.
cameron.mcinally added a comment.
This revision is now accepted and ready to land.

LGTM

================
Comment at: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:1429
+                                         PtrInfo.getWithOffset(Offset), MemVT));
+    else
       Stores.push_back(DAG.getStore(DAG.getEntryNode(), dl, Node->getOperand(i),
----------------
Nit: Not specific to this patch, but I think we can hoist `Node->getOperand(i).getValueType()` out of the loop. All the BUILD_VECTOR/CONCAT_VECTOR operand types should be the same.

Looking deeper, the BUILD_VECTOR description is a little vague though:

```
   /// The types of the operands must all be
   /// the same and must match the vector element type, except that integer types
   /// are allowed to be larger than the element type, in which case the operands
   /// are implicitly truncated.
```

I assume the larger integer operand types must all be the same type. Maybe I'm misinterpreting this though. 

Just queried llvm-dev about BUILD_VECTOR and will report back...

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D83303/new/

https://reviews.llvm.org/D83303