assembly - Efficient three valued compare -


for unsigned integers getting result of 

if (a>b) => 1 if (a=b) => 0 if (a<b) => -1

can optimized branchless version

return ((a > b) - (a < b))

this can written x86 assembly so:

4829d1           cmp rcx,rdx 0f94c1           setz cl     19c0             sbb eax,eax     83d8ff           sbb eax,-$01     d3e8             shr eax,cl  13 bytes in total

is there way without branches in less 5 instructions or in fewer bytes?

a solution less bytes (11 bytes) , 1 less instruction (4 instructions) may faster:

483bca          cmp     rcx,rdx 1bc0            sbb     eax,eax 483bd1          cmp     rdx,rcx 83d000          adc     eax,0

this can improved upon 10 bytes if have spare register known null.

... 11d8            adc     eax,ebx

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