This improves my PC's performance on RS2 Hoth by... 0.1% or so, which I
think is within the margin of error. But this change also cuts down on
boilerplate.
If the call to `Open` a perf map fails don't set `s_is_enabled` (though
it could already be true if you're also using VTUNE) and don't call
`std::setvbuf` with a null stream.
Also fix a typo in a comment (`if` -> `in`)
If all inputs to an fmadds instruction (including cousins like fmsubs,
fnmadd...) are single-precision, then the result is identical between a
double-precision calculation with an error-free transform (whether the
calculation is fused or not) and a single-precision FMA instruction
(must be fused). So as a performance optimization in JitArm64, if we
were going to use double precision with EFT but the inputs are singles,
instead we'll use a normal single-precision FMA instruction without
anything extra. This lets us skip both the EFT and double-to-single
conversions.
Also renaming `inaccurate_fma` to `nonfused` because it's confusing that
`inaccurate_fma` and `m_accurate_fmadds` have such similar names
despite controlling separate things.
If result_reg is set to a temporary register instead of VD because of
accurate NaNs, there's no need to allocate a secondary temporary
register because of inaccurate FMA.