[PATCH] D126939: [SLP] Avoid converting undef to poison when gathering.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

Please change the summary (commit message) to describe the commit caused regression.
It helps other rolling-update users to find a stable state in llvm.



================
Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:7564
     }
-    UniqueValues.append(VF - UniqueValues.size(),
-                        PoisonValue::get(VL[0]->getType()));
+    // Don't convert an undef to poison while padding.
+    UniqueValues.append(
----------------
Better to reword the comment what this append does, and how it avoids appending poison.

The new code isn't clear how poison is avoided (while the old is).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126939/new/

https://reviews.llvm.org/D126939