[PATCH] D40524: Handle the case of live 16-bit subregisters in X86FixupBWInsts

[Andrei Elovikov via Phabricator via llvm-commits]

a.elovikov added a comment.

I'm not sure if the following is possible/legal but it fails even with this patch:

  body:             |
    bb.0:
      successors:
      liveins: %ch, %bl
  
      %cl = MOV8rr %bl, implicit-def %cx, implicit killed %ch, implicit-def %eflags
      ; CHECK-NOT: MOV32rr
      RETQ %cx

If that's a valid testcase than "a little more checking to do." (isLive before this patch) has to be fixed. If it's invalid - we'd need an assert for that too (or some mir-verify?). However, that should not be a part of this change, probably. Hence, just asking what's your opinion about that testcase.


https://reviews.llvm.org/D40524