[PATCH] D81634: Remove assert from ShuffleVectorInst

[Sanjay Patel via Phabricator via llvm-commits]

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

LGTM



================
Comment at: llvm/lib/IR/Instructions.cpp:2056
   }
-  assert((UsesLHS ^ UsesRHS) && "Should have selected from exactly 1 source");
-  return true;
+  // Allow for degenerate case: completely undef mask means neither source is used.
+  return UsesLHS || UsesRHS;
----------------
Formatting: 80-column.


================
Comment at: llvm/test/Transforms/CodeGenPrepare/X86/cgp_shuffle_crash.ll:13
+CF:                                               ; preds = %CF, %BB
+  %Cmp82 = icmp slt i32 480483, undef
+  br i1 undef, label %CF, label %CF242
----------------
bugpoint tends to produce tests like this with undef/unused values, and then those tests wiggle or become worthless when unrelated improvements are made. For that reason, I still prefer my more-defined version of the test. :)


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81634/new/

https://reviews.llvm.org/D81634