[PATCH] D31525: InstSimplify: Add a hook for shufflevector

[Sanjay Patel via Phabricator via llvm-commits]

spatel added reviewers: sanjoy, nlopes, majnemer.
spatel added a comment.

Why would a shuffle with undef mask automatically return undef? For example:
shufflevector <2 x i8> <i8 42, i8 42>, <2 x i8> <i8 42, i8 42>, <2 x i32> undef

Should this be constant folded to <i8 42, i8 42> , <2 x i8> undef or something else?



================
Comment at: lib/Analysis/InstructionSimplify.cpp:4114-4115
+
+  auto Op0Const = dyn_cast<Constant>(Op0);
+  auto Op1Const = dyn_cast<Constant>(Op1);
+
----------------
Prefer 'auto *' to make the pointer-ness of the cast explicit.


Repository:
  rL LLVM

https://reviews.llvm.org/D31525