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Re: -mno-80387 and MMX autovectorisation
- From: Rask Ingemann Lambertsen <rask at sygehus dot dk>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: Uros Bizjak <ubizjak at gmail dot com>, GCC Development <gcc at gcc dot gnu dot org>, Roger Sayle <roger at eyesopen dot com>
- Date: Sun, 16 Jul 2006 16:00:27 +0200
- Subject: Re: -mno-80387 and MMX autovectorisation
- References: <email@example.com> <F8026F98-43E0-4729-B6AB-17DF2C3A1724@physics.uc.edu>
On Thu, Jun 08, 2006 at 08:50:13AM -0700, Andrew Pinski wrote:
> On Jun 7, 2006, at 11:13 PM, Uros Bizjak wrote:
> >Current mainline gcc can efficiently disable x87 instruction when
> >-mno-80387 switch is used. In this case, MMX registers can be used for
> >the autovectorisation even without emms or femms instructions to
> >switch back to x87 mode.
> I don't think so, because another function could use x87 instructions
> even without you knowing it.
But it would not be difficult to check regs_ever_live and emit the
(f)emms instruction in the epilogue if an MMX register was ever used.
Rask Ingemann Lambertsen