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RE: [patches] Re: Mode switching for i386 (Was: Re: [patches] Re: better fp truncation sequence on i386)
- To: "'Jan Hubicka'" <jh at suse dot cz>, Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org, patches at x86-64 dot org, "Prince, Timothy C" <timothy dot c dot prince at intel dot com>, gcc at gcc dot gnu dot org
- Subject: RE: [patches] Re: Mode switching for i386 (Was: Re: [patches] Re: better fp truncation sequence on i386)
- From: "Prince, Timothy C" <timothy dot c dot prince at intel dot com>
- Date: Tue, 26 Jun 2001 06:48:29 -0700
-----Original Message-----
From: Jan Hubicka [mailto:jh@suse.cz]
Sent: Tuesday, June 26, 2001 1:06 AM
To: Richard Henderson; Jan Hubicka; gcc-patches@gcc.gnu.org;
patches@x86-64.org; timothy.c.prince@intel.com; gcc@gcc.gnu.org
Subject: Re: [patches] Re: Mode switching for i386 (Was: Re: [patches]
Re: better fp truncation sequence on i386)
> Two solutions. One, spill in XFmode, which some people have
> wanted for various purposes anyway. Two, recognize that such
>Spilling in the XFmode is about 5 times more expensive, so we shouldnot go
for it by >>default.
XFmode spills will be expensive if they produce cache line splits (i.e.
16-byte alignments must be maintained, thus eating more cache). My last
copy of the Lahey/Fujitsu compiler had problems with this.