[Bug rtl-optimization/85925] [7/8/9 regression] Mis-compilation at -02, masking with 257 goes wrong in combine

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85925

--- Comment #10 from Segher Boessenkool <segher at gcc dot gnu.org> ---
I get this:

       alpha  100.905%  
         arm  100.072%  
         c6x  100.000%  
        csky  100.063%  
       h8300  100.000%  
        i386  100.000%  
  microblaze  100.001%  
        mips  100.052%  
      mips64  100.043%  
       nios2  100.000%  
      parisc  100.049%  
    parisc64  100.031%  
   powerpc64   99.952%   
     riscv64  100.049%  
        s390  100.000%  
          sh  100.006%  
     shnommu  100.002%  
       sparc  100.003%  
     sparc64  100.007%  
      x86_64  100.000%

(the other 9 did not build, sigh.  And this is code size).

The alpha one looks really bad.  Only the powerpc64 is a win.