[dev.simd] simd, cmd/compile: generated files to add 'blend' and 'blendMasked'
Generated by arch/internal/simdgen CL 693175
These methods are not public because of simdgen-induced name/signature
issues, and because their addition was motivated by the need for
emulation tools.
The specific name signature problems are:
1) one set of instructions has the "Masked" suffix (because of how
that is incorporated into names) and the other set does not (though I
suppose the operation could be renamed).
2) because the AVX2 instruction is bytes-only, to get the signature
right, requires "OverwriteBase" but OverwriteBase also requires
OverwriteClass and "simdgen does not support [OverwriteClass] in
inputs".
3) the default operation order is false, true, but we want this in a
"x.Merged(y, mask)" that pairs with "x.Masked(mask)" where the true
case is x and the false case is y/zero, but the default ordering for
VPBLENDVB and VPBLENDMB is false->x and true->y.
4) VPBLENDVB only comes in byte width, which causes problems
for floats.
All this may get fixed in the future, for now it is just an
implementation detail.