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Re: [PATCH] Fix PR optimization/10876
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Eric Botcazou <ebotcazou at libertysurf dot fr>
- Cc: Chris Lattner <sabre at nondot dot org>, kenner at vlsi1 dot ultra dot nyu dot edu, gcc-patches at gcc dot gnu dot org
- Date: Sat, 24 May 2003 02:51:47 -0400
- Subject: Re: [PATCH] Fix PR optimization/10876
- References: <Pine.LNX.4.44.0305232040530.3374-100000@nondot.org> <200305240738.35883.ebotcazou@libertysurf.fr>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Sat, May 24, 2003 at 07:39:35AM +0200, Eric Botcazou wrote:
> > http://gcc.gnu.org/onlinedocs/gccint/Insn-Canonicalizations.html#Insn%20Ca
> >nonicalizations
>
> Yes, thanks for the link.
>
> > Explanation:
> > (minus (reg) (const_int))
> > Should be represented as:
> > (plus (reg) (-const_int))
>
> There is exactly one case for which this transformation is not possible on
> SPARC: with CONST_INT == -4096. So we'll resort to putting the constant in a
> register.
Better add a new constraint for arith_4096_operand and
arith_double_4096_operand and change *adddi3_sp64 and *addsi3 to handle that
alternative.
Jakub