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From: Toon Moene <toon@moene.indiv.nluug.nl>
To: Richard Henderson <rth@cygnus.com>
Cc: egcs@cygnus.com
Subject: Re: more on fortran array indexing
Date: Sat, 04 Oct 1997 08:12:00 -0000	[thread overview]
Message-ID: <9710041510.AA01646@moene.indiv.nluug.nl> (raw)
In-Reply-To: <19971003110425.58522@dot.cygnus.com>

I wrote:

>> Please try the following patch:
>>
>> 	* fold-const (fold): Also simplify FLOOR_DIV_EXPR
>> 	  iff dividend is a multiple of divisor

Richard:

>  No good.  The problem being, I believe, that n*64 is
>  wrapped in a save_expr, and so we can't get rid of it.
>  I'd actually already tried making the ARRAY_REF expansion
>  use EXACT_DIV_EXPR..

After some testing, I'm less and less convinced that this is the  
problem.  There are still "subreg ... sign_extend"'s lying around in  
the -dL (resid.f.loop) output, which means that there are  
"unnecessary" conversions being done.

Note that fold-const.c knows how to get rid of divisions within  
SAVE_EXPR's (at least in principle).

IMHO, there's nothing wrong with the division.

Unfortunately, I haven't been able to track the real problem down.

Cheers,
Toon.

  reply	other threads:[~1997-10-04  8:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1997-10-02 13:04 Richard Henderson
1997-10-03  1:33 ` Toon Moene
1997-10-03 11:05   ` Richard Henderson
1997-10-04  8:12     ` Toon Moene [this message]
1997-10-05  3:12       ` Toon Moene
1997-10-26  9:05   ` Jeffrey A Law

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