[PATCH] D67192: [X86] Use MOVSX instead of CBW to extend i8 to AX for i8 sdiv.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

You can't peephole replace MOVSX %al, %eax with CBW without proving that the upper 48-bits of %rax are dead. CBW is  equivalent to MOVSX %al, %ax which leaves the upper 48-bits unmodified.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67192/new/

https://reviews.llvm.org/D67192