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Re: [PATCH, i386]: Rewrite x87 sqrt patterns
- From: Michael Matz <matz at suse dot de>
- To: Andrew Haley <aph at redhat dot com>
- Cc: Uros Bizjak <ubizjak at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 22 Nov 2006 14:04:49 +0100 (CET)
- Subject: Re: [PATCH, i386]: Rewrite x87 sqrt patterns
- References: <45636E1E.email@example.com> <firstname.lastname@example.org>
On Wed, 22 Nov 2006, Andrew Haley wrote:
> Uros Bizjak writes:
> > The i386 sqrt patterns doesn't truncate the result of fsqrt x87
> > instruction.
> And neither do add, sub. mult, or div. What's special about sqrt that
> it deserves this treatement?
Right. If you _really_ want to fix x87 you'll have to explicitely
truncate every intermediate result, just like -ffloat-store. I guess
nobody wants that, so why do it for sqrt?