what's the best way to toggle simd register

[blackoil]

toggle xmm0: //cost 2 instructions, 2 registers
vpcmpeqd xmm1,xmm1,xmm1
vpcmpeqd xmm0,xmm0,xmm1

is there single instruction method?

[Combuster]

By using a memory operand pointing to a constant (pxor to all ones would be the most obvious). Actually inverting the preceding test so you don't need this in the first place would be a much better idea though

You currently appear to be doing

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x = (x == true) ? true : false;

instead of false : true, so it doesn't actually toggle anything.

[blackoil]

it should be

Code: Select all

vpcmpeqd xmm1,xmm1,xmm1
vpxor xmm0,xmm0,xmm1

I wonder why there isn't vpnot instruction.