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Re: [PATCH, i386] Optionally use %xmm0 to return float and/or doublevalues

> When you make the new ABI user visible (which I'm not 100% sure
> is the right thing, especially in the 4.0 timeframe), then it should
> IMHO be a full new ABI, that uses not just return value passing in
> register, but also argument passing in registers (at least float,
> double arguments, structs containing just one, two floats/doubles or
> something similar), otherwise we end up with a multitude of different > ABIs.

This would surely not be the right thing in the 4.0 timeframe. Also, a better ABI may also take advantage of regparm, etc., and it would be much bigger a work. Unlike this hack, that effort would need to coordinate at least with libc, and I'm not sure if the x86_64 future is "near enough" that it's worth it.

However, tomorrow (unless Uros beats me to it :-) I'll benchmark povray: a much simpler patch that only does this for local functions might still provide a good bang for the buck.


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