From: Eric Botcazou <ebotcazou@adacore.com>
To: gcc-patches@gcc.gnu.org
Cc: Richard Sandiford <rdsandiford@googlemail.com>,
Richard Sandiford <richard.sandiford@arm.com>,
Alan Hayward <Alan.Hayward@arm.com>,
"steven@gcc.gnu.org" <steven@gcc.gnu.org>
Subject: Re: [PATCH][rtlanal.c][BE][1/2] Fix vector load/stores to not use ld1/st1
Date: Tue, 13 Jan 2015 19:04:00 -0000 [thread overview]
Message-ID: <13670880.MKCSlOSr3D@polaris> (raw)
In-Reply-To: <87a91qg50x.fsf@googlemail.com>
> Sorry for the slow response. Jeff has approved the patch in the
> meantime, but I didn't want to go ahead and apply it while there
> was still disagreement...
I still think that it isn't appropriate to short-circuit the main computation
as the patch does, but I don't want to block it after Jeff's approval.
> (1) we have a non-paradoxical subreg;
> (2) both (reg:ymode xregno) and (reg:xmode xregno) occupy full
> hard registers (no padding or unused upper bits);
> (3) (reg:ymode xregno) and (reg:xmode xregno) store the same number
> of bytes (X) in each constituent hard register;
> (4) the offset is a multiple of X, i.e. the data we're accessing
> is aligned to a register boundary; and
> (5) endianness is regular (no differences between words and bytes,
> or between registers and memory)
OK, that's a nice translation of the new code. :-)
It seems to me that the patch wants to extend the support of generic subregs
to modes whose sizes are not multiple of each other, which is a requirement of
the existing code, but does that in a very specific case for the sake of the
ARM port without saying where all the above restrictions come from.
--
Eric Botcazou
next prev parent reply other threads:[~2015-01-13 18:57 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-12 11:08 Alan Hayward
2014-12-12 16:21 ` Richard Sandiford
2014-12-13 11:34 ` Eric Botcazou
2014-12-15 9:21 ` Richard Sandiford
2014-12-15 20:52 ` Eric Botcazou
2014-12-15 21:56 ` Richard Sandiford
2014-12-19 22:53 ` Eric Botcazou
2015-01-10 14:59 ` Richard Sandiford
2015-01-13 19:04 ` Eric Botcazou [this message]
2015-01-14 8:37 ` Jeff Law
2015-01-14 9:55 ` Marcus Shawcroft
2015-01-20 21:45 ` Richard Sandiford
2015-01-21 1:48 ` Eric Botcazou
2015-01-21 18:03 ` Richard Sandiford
2015-01-14 7:48 ` Jeff Law
2015-01-09 7:12 ` Jeff Law
-- strict thread matches above, loose matches on Subject: below --
2014-12-10 9:51 Alan Hayward
2014-12-10 10:25 ` Marcus Shawcroft
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