[PATCH] D126638: [CGP] Also freeze ctlz/cttz operand when despeculating

Wed Jun 8 07:15:06 PDT 2022

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

https://alive2.llvm.org/ce/z/iwd4ba
This is needed for correctness, so LGTM.

It might be good to add tests for other targets. I didn't step through this to see why, but the code for AArch and ARM actually looks better when we re-use the frozen value.

  rbit	w9, w0
  mov	w8, #32
  clz	w9, w9
  cmp	w0, #0
  csel	w0, w8, w9, eq

vs.

  rbit	w8, w0
  clz	w0, w8

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126638/new/

https://reviews.llvm.org/D126638