[PATCH] D24279: [InstCombine] canonicalize vector select with constant vector condition to shuffle

[Michael Kuperstein via llvm-commits]

mkuper added a comment.

Thanks Sanjay, as I wrote on the email thread, I think this is probably the right canonicalization.
Did you happen to check that we don't regress codegen for the IR tests that changed? At least X86? (This should probably go in even if it does regress some cases, but a PR would be good.)


================
Comment at: test/Transforms/InstCombine/select.ll:1794
@@ +1793,3 @@
+; CHECK-LABEL: @cannot_canonicalize_to_shuffle2(
+; CHECK-NEXT:    [[SEL:%.*]] = select <4 x i1> <i1 true, i1 undef, i1 false, i1 icmp sle (i16 ptrtoint (i32* @g to i16), i16 4)>, <4 x i32> %a, <4 x i32> %b
+; CHECK-NEXT:    ret <4 x i32> [[SEL]]
----------------
Yikes.


https://reviews.llvm.org/D24279