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In s_cmp_lg_i32 what LG stands for?

Question asked by realhet on Jan 11, 2014
Latest reply on Jan 21, 2014 by realhet

Hi,

 

I just wonder how comes this abbreviation in the GCN ISA.

In the manual it also mentions that it should be NotEqual. -> S_CMP_{EQ,NE,GT,GE,LE,LT}_{I32,U32}

But when it comes to the section where the details for each instructions are, then it says about LG instead of NE.

 

Another interesting thing is, that every v_cmp instruction has it's negated twin: for example there is

v_cmp_lg_f32   //D(sgpr).u = (S0 <> S1), signal on sNaN input only; D = VCC in VOPC

and also

v_cmp_neq_f32  //D(sgpr).u = !(S0 == S1), signal on sNaN input only; D = VCC in VOPC

It seems like both of them are for the same thing, but they have different machine codes. Anyone knows why?

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