[PATCH] D34652: [x86] add SBB optimization for SETAE (uge) condition code

[Zvi Rackover via Phabricator via llvm-commits]

zvi added inline comments.


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Comment at: test/CodeGen/X86/sbb.ll:149
 ; CHECK:       # BB#0:
-; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    cmpl %esi, %edi
+; CHECK-NEXT:    sbbl %eax, %eax
----------------
AFAIK, the processor does avoid false-dependency stalls for the case 'sbb EAX EAX' (unlike xor's and sub's).
So we may want to ensure a 'xor EAX EAX' is placed before.


https://reviews.llvm.org/D34652