[Bug target/95737] PPC: Unnecessary extsw after negative less than

[guihaoc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95737

HaoChen Gui <guihaoc at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |guihaoc at gcc dot gnu.org

--- Comment #6 from HaoChen Gui <guihaoc at gcc dot gnu.org> ---
//source code
unsigned long long negativeLessThan(unsigned long long a, unsigned long long b)
{
   return -(a < b);
}

//P8 with -O2
        subfc 4,4,3
        subfe 3,3,3
        extsw 3,3


//P9 with -O2
        li 10,0
        li 9,1
        cmpld 0,3,4
        isel 3,9,10,0
        neg 3,3

Seems cmp+isel on P9 is sub-optimal.