[PATCH] D63318: [DAGCombine] Teach DAGCombine to fold the aext + select pattern

[Qing Shan Zhang via Phabricator via llvm-commits]

steven.zhang marked an inline comment as done.
steven.zhang added inline comments.


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Comment at: llvm/test/CodeGen/X86/cmov-promotion.ll:130
+; CMOV-NEXT:    movl $4294967295, %eax # imm = 0xFFFFFFFF
+; CMOV-NEXT:    cmovneq %rcx, %rax
 ; CMOV-NEXT:    retq
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craig.topper wrote:
> This is slightly worse. Maybe don't do this when zext is free?
I check the scheduling information for cmovneq and cmovnel, both latency are 1. I didn't catch the "slightly worse" you mean ... Could you explain it more, as I am new to X86 instr. Thank you!


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