[Bug target/107172] [13 Regression] wrong code with "-O1 -ftree-vrp" on x86_64-linux-gnu since r13-1268-g8c99e307b20c502e

["crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107172

--- Comment #19 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to H.J. Lu from comment #18)
> (In reply to Segher Boessenkool from comment #16)
> > Hi Roger,
> > 
> > (In reply to Roger Sayle from comment #15)
> > > Yes, a COMPARE rtx can be used to set various flags on x86, but many other
> > > operations also legitimately set and/or use MODE_CC, often in a parallel
> > > with the primary operation.
> > 
> > *Any* MODE_CC setter sets the flags as-if from a compare.  This is what
> > MODE_CC *is*.
> > 
> > Setting something as ne:CC and then using it as somethingelse:CC has no
> > defined meaning.
> 
> This
> 
> (parallel [
>             (set (reg:SI 97) 
>                 (neg:SI (ltu:SI (reg:CCC 17 flags)
>                         (const_int 0 [0]))))
>             (clobber (reg:CC 17 flags))
>         ])
> 
> still won't work correctly if reg:CCC 17 flags is set by a compare of
> 2 known values.

I guess Segher means it should be NE instead of LTU in the
x86_mov<mode>cc_0_m1_neg, since the setters is NE to const 0.

 (ne:CCC (reg:SI 87 [ a_lsm.8 ])
                    (const_int 0 [0])))

 (define_expand "x86_mov<mode>cc_0_m1_neg"
   [(parallel
     [(set (match_operand:SWI48 0 "register_operand")
-         (neg:SWI48 (ltu:SWI48 (reg:CCC FLAGS_REG) (const_int 0))))
+         (neg:SWI48 (ne:SWI48 (reg:CCC FLAGS_REG) (const_int 0))))
      (clobber (reg:CC FLAGS_REG))])])

It can pass the PR, but failed pr101617.c, the f1 case.

generate:
        testl   %edi, %edi
        movl    $1, %edx
        movl    $-1, %eax
        cmove   %edx, %eax

origin:
        negl    %edi
        sbbl    %eax, %eax
        orl     $1, %eax