From: Denis Chertykov <chertykov@gmail.com>
To: Georg-Johann Lay <avr@gjlay.de>
Cc: gcc-patches@gcc.gnu.org,
Eric Weddington <eric.weddington@atmel.com>,
Anatoly Sokolov <aesok@post.ru>
Subject: Re: [Path,AVR]: Improve loading of 32-bit constants
Date: Wed, 06 Jul 2011 13:57:00 -0000 [thread overview]
Message-ID: <CADOs=za9td8ge_3K1m23oRP_AHEXGgGGy1exK5RyGP5ZQizoaQ@mail.gmail.com> (raw)
In-Reply-To: <4E144C61.60600@gjlay.de>
2011/7/6 Georg-Johann Lay <avr@gjlay.de>:
> For loading a 32-bit constant in a register, there is room for
> improvement:
>
> * SF can be handled the same way as SI and therefore the patch
> adds a peep2 to produce a *reload_insf analogon to *reload_insi.
>
> * If the destination register overlaps NO_LD_REGS, values already
> loaded into some other byte can be reused by a simple MOV.
> This is helpful then moving values like, e.g. -2, -100 etc. because
> all high bytes are 0xff.
>
> * 0.0f can be directly moved to memory.
>
> * The mov insns contain "!d" constraint. I see no reason to make "d"
> expensive and discourage use of d-regs. A "*d" to hide is better
> because it does it neither puts additional pressure on "d" nor
> discourages "d".
>
I would like to have a real code examples.
Denis.
next prev parent reply other threads:[~2011-07-06 13:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-06 11:54 Georg-Johann Lay
2011-07-06 13:57 ` Denis Chertykov [this message]
2011-07-06 16:08 ` Georg-Johann Lay
2011-07-06 17:27 ` Denis Chertykov
2011-07-06 18:06 ` Georg-Johann Lay
2011-07-06 18:40 ` Georg-Johann Lay
2011-07-07 7:38 ` Denis Chertykov
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