Re: Inline assembler fallback for _FPU_SETCW() missing in MINGW libraries (issue 577450043 by address@hidden)

[Thomas Morley]

Am Sa., 1. Feb. 2020 um 16:49 Uhr schrieb David Kastrup <address@hidden>:
>
> Thomas Morley <address@hidden> writes:
>
> > Am Sa., 1. Feb. 2020 um 12:39 Uhr schrieb David Kastrup <address@hidden>:
> >>
> >> Dan Eble <address@hidden> writes:
> >>
> >> > On Feb 1, 2020, at 05:05, David Kastrup <address@hidden> wrote:
> >> >>
> >> >> Frankly, I think that it would be better if our Windows executables just
> >> >> moved to 64bit but that seems like the more complicated option yet. And
> >> >> 32bit systems kept around a whole lot longer even after processors
> >> >> became 64bit-capable because they tended to require less memory.
> >> >
> >> > You provided a lot of good information in your post, but the
> >> > conclusion was not entirely clear.
> >> > Are you suggesting requiring SSE2 at this time?
> >>
> >> Yes.  It appears to get used anyway for 64bit executables, and it seems
> >> safe enough to demand it for 32bit executables.
> >>
> >> For SSE there would be the danger of libraries stomping over the
> >> registers that share memory with the FPU stack, but I think that SSE2 is
> >> not affected.
> >>
> >> --
> >> David Kastrup
> >>
> >
> > Well, Arnold encountered the problem (iirc he will not be online
> > during the weekend) and there may several other older 32-bit OS
> > around.
> > What shoud those people do?
>
> Nothing?  I am currently proposing that we compile with
>
> -mfpmath=sse -msse2
>
> as options which should shift arithmetic off to the SSE2 instruction set
> which doesn't work with 80-bit arithmetic.  That would be a default way
> of compilation.
>
> --
> David Kastrup

Ok, thanks for the explanation.

Iiuc, this would make this patch superfluous and it should be abandoned.
As I'm only shepherding it, I'll wait for Arnold.
For now I'll set the issue to 'waiting' to get it out of Jame's hairs for now.

Tbh, I have no clue how to implement a -mfpmath=sse -msse2 option myself.

Thanks,
  Harm

P.S.
Just seen the patch at
https://codereview.appspot.com/565600045/