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Re: [PATCH, x86_64]: Provide longlong.h definitions for 128bit operations
- From: Eric Botcazou <ebotcazou at libertysurf dot fr>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Rask Ingemann Lambertsen <rask at sygehus dot dk>, Uros Bizjak <ubizjak at gmail dot com>, Paolo Bonzini <bonzini at gnu dot org>, Chris Lattner <clattner at apple dot com>
- Date: Fri, 18 May 2007 22:38:35 +0200
- Subject: Re: [PATCH, x86_64]: Provide longlong.h definitions for 128bit operations
- References: <464B6834.1050600@gmail.com> <200705180912.20137.ebotcazou@libertysurf.fr> <m3r6peaxku.fsf@localhost.localdomain>
> From the backend perspective, the best way to take advantage of
> lower-subreg is conceptually simple if sometimes awkward in practice:
> for multi-word operations, use define_insn_and_split and split the
> insns before reload.
OK, I see, thanks.
> For a non-CC0 style machine things are simpler. Just split multi-word
> operations before reload. There was never any particular need to wait
> until after reload to split them in the past. And now you really
> don't want to wait.
Of course SPARC-V8 is the perfect counter-example since you have a pairing
instruction "ldd" for consecutive integer registers. :-)
--
Eric Botcazou