From: Georg-Johann Lay <avr@gjlay.de>
To: Denis Chertykov <chertykov@gmail.com>
Cc: gcc-patches@gcc.gnu.org, Anatoly Sokolov <aesok@post.ru>,
Eric Weddington <eric.weddington@atmel.com>
Subject: Re: [Patch,AVR]: Fix PR27663
Date: Wed, 11 May 2011 19:39:00 -0000 [thread overview]
Message-ID: <4DCAD237.3010008@gjlay.de> (raw)
In-Reply-To: <BANLkTintaKGhzHAEv8yuDcKhOALYgNRa+A@mail.gmail.com>
Denis Chertykov schrieb:
> 2011/5/2 Georg-Johann Lay <avr@gjlay.de>:
>
>>This is a fix for an optimization flaw when a long value is composed
>>from byte values.
>>
>>For -fsplit-wide-types (which is still default for avr) the code is
>>worse than with -fno-split-wide-types. The code for the test case is
>>better in either situations, i.e. compared to code without the patch,
>>but it is still not optimal.
>>
>>Fixing this by some combine patterns is the only thing the BE can do.
>>I did not write more complex patterns because things get too complex
>>with little performance gain.
>>
>>Tested without regressions.
>>
>>Johann
>>
>>2011-05-02 Georg-Johann Lay <avr@gjlay.de>
>>
>> PR target/27663
>> * config/avr/predicates.md (const_8_16_24_operand): New predicate.
>> * config/avr/avr.md ("*ior<mode>qi.byte0",
>> "*ior<mode>qi.byte1-3"): New define_insn_and_split patterns.
>>
> I'm sorry, but I dot'n like to have a both combiner related patches in
> port because code improvement isn't much and your patterns are
> difficult to understand and maintain.
>
> May be somebody else have a different oppinion ?
> I'm open to discussion.
>
> Denis.
Let me add that the patch is generic enough to also improve ORing HI
against QI like described in
http://gcc.gnu.org/PR41076
which is not uncommon on avr.
Johann
next prev parent reply other threads:[~2011-05-11 18:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-02 14:31 Georg-Johann Lay
2011-05-02 15:18 ` Denis Chertykov
2011-05-06 13:54 ` Georg-Johann Lay
2011-05-11 19:39 ` Georg-Johann Lay [this message]
2011-05-13 9:34 ` Denis Chertykov
2011-05-16 17:40 ` Georg-Johann Lay
2011-05-16 19:37 ` Denis Chertykov
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