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Re: What's the status of autovectorization for MMX and 3DNow!?
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: "Zuxy Meng" <zuxy dot meng at gmail dot com>
- Date: Mon, 11 Dec 2006 21:41:16 +0100
- Subject: Re: What's the status of autovectorization for MMX and 3DNow!?
Hello!
> I'm particularly interested in this patch
> (http://gcc.gnu.org/ml/gcc-patches/2005-07/msg01128.html); pretty
nice for
> users of Pentium 3 and Athlon. Has it been or will it be integrated into
> mainline?
This patch heavily depends on the functionality of optimize mode
switching pass. Unfortunatelly, there is currently no way to tell
optimize_mode_switching() which modes are exclusive. Due to the way how
the emms switching patch was designed, it expects that either MMX or X87
mode can be active at once, to properly switch between x87 and MMX
registers.
PR target/19161 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161)
comment #17 has an example of the control flow that can block both
register sets at once. Otherwise, the patch works as expected.
Uros.