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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/44883] Combine separate shift and add instructions into a single one
Date: Fri, 09 Jul 2010 00:06:00 -0000 [thread overview]
Message-ID: <20100709000634.27342.qmail@sourceware.org> (raw)
In-Reply-To: <bug-44883-17659@http.gcc.gnu.org/bugzilla/>
------- Comment #3 from pinskia at gcc dot gnu dot org 2010-07-09 00:06 -------
(In reply to comment #2)
> Give it a single register, the cost is 6. Give it the rtx (plus (reg 144) (reg
> 143)), the cost is 4. So a single register is more expensive than a plus
> expression, not reasonable.
And that causes forwprop to do what it does; it is a lower total cost according
to the cost function :).
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |missed-optimization
Last reconfirmed|0000-00-00 00:00:00 |2010-07-09 00:06:33
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44883
next prev parent reply other threads:[~2010-07-09 0:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-08 23:18 [Bug rtl-optimization/44883] New: " carrot at google dot com
2010-07-08 23:22 ` [Bug target/44883] " pinskia at gcc dot gnu dot org
2010-07-09 0:04 ` carrot at google dot com
2010-07-09 0:06 ` pinskia at gcc dot gnu dot org [this message]
2010-07-09 22:11 ` carrot at google dot com
[not found] <bug-44883-4@http.gcc.gnu.org/bugzilla/>
2021-09-26 22:43 ` pinskia at gcc dot gnu.org
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