[PATCH] D153846: [SelectionDAG] do not fold (sext i32 undef to i64) to 0

[Nikita Popov via Phabricator via llvm-commits]

nikic requested changes to this revision.
nikic added a comment.
This revision now requires changes to proceed.
Herald added a subscriber: StephenFan.

This is not legal, because the result of sext must have the top bits either all zero or all ones, which undef does not guarantee. This change will lead to miscompiles.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D153846/new/

https://reviews.llvm.org/D153846