Re: floating point woes on i386

At Tue, 30 Sep 2025 12:00:31 +0200, Jörg Sonnenberger <[email protected]> wrote:
Subject: Re: floating point woes on i386
> 
> On 9/30/25 9:30 AM, Greg A. Woods wrote:
> 
> > At Sat, 27 Sep 2025 10:36:59 +0200, Joerg Sonnenberger <[email protected]> wrote:
> > Subject: Re: floating point woes on i386
> >> 
> >> There is on newer i386 also the option of
> >> using -mfpmath=sse. That's strictly
> >> speaking the only way to get IEEE754
> >> semantics on i386.
> > 
> > On NetBSD/i386 10.0 with the system's GCC-10.5 the -mfpmath=sse option
> > doesn't actually do anything:
> 
> Well, of course. You also need to use a
> CPU that supports SSE2 and/or enable the
> feature with -msse2.

Well, of course indeed!  Thanks for the reminder!  GCC is so much fun!
It is all really well documented in NetBSD's gcc(1) manual page, if I
had dared to read enough of it carefully!

Yes, with "-msse2 -mfpmath=sse" paranoia completes with zero flaws.

Adding "+387" to the latter also requires "-fexcess-precision=standard",
i.e. "-std=c89", but then it also completes, possibly slightly faster,
with zero flaws.

-- 
					Greg A. Woods <[email protected]>

Kelowna, BC     +1 250 762-7675           RoboHack <[email protected]>
Planix, Inc. <[email protected]>     Avoncote Farms <[email protected]>

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