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From: "bonzini at gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/39543] [4.4 Regression] Reload failure on mplayer from SVN
Date: Tue, 24 Mar 2009 15:04:00 -0000 [thread overview]
Message-ID: <20090324150347.14379.qmail@sourceware.org> (raw)
In-Reply-To: <bug-39543-87@http.gcc.gnu.org/bugzilla/>
------- Comment #4 from bonzini at gnu dot org 2009-03-24 15:03 -------
The only thing to be careful is to have set_reg_equal == FALSE if the insn has
multiple sets, and find which set in a multiple-set insn is actually referring
to USE (a combination of note_stores and loc_mentioned_in_p will do). Such a
patch is definitely backportable to 4.4 even if it is not ready for 4.4.0.
However, I'm not sure it is good to have the best possible addressing mode in
an asm, because I wonder if this could cause other kinds of reload failure.
Think of:
char p[10];
...
a = b * 4 + c;
asm ("" : : "m" (p[a]))
Which fwprop would likely change to a base/index/displacement address, with 2
registers gone.
Setting cse_not_expected in practice would not use an addressing mode that is
more complicated than the one specified by the user; for an asm, I think this
is actually the least surprising behavior.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39543
next prev parent reply other threads:[~2009-03-24 15:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-24 11:25 [Bug rtl-optimization/39543] New: " jakub at gcc dot gnu dot org
2009-03-24 11:28 ` [Bug rtl-optimization/39543] " jakub at gcc dot gnu dot org
2009-03-24 12:54 ` jakub at gcc dot gnu dot org
2009-03-24 14:18 ` jakub at gcc dot gnu dot org
2009-03-24 15:04 ` bonzini at gnu dot org [this message]
2009-03-25 13:10 ` jakub at gcc dot gnu dot org
2009-03-25 15:49 ` jakub at gcc dot gnu dot org
2009-03-25 16:49 ` bonzini at gnu dot org
2009-03-25 18:32 ` jakub at gcc dot gnu dot org
2009-03-26 8:47 ` bonzini at gnu dot org
2009-03-26 13:42 ` matz at gcc dot gnu dot org
2009-03-30 14:45 ` [Bug rtl-optimization/39543] [4.4/4.5 " rguenth at gcc dot gnu dot org
2009-04-14 13:53 ` bonzini at gnu dot org
2009-04-14 13:59 ` matz at gcc dot gnu dot org
2009-04-14 14:02 ` bonzini at gnu dot org
2009-04-21 16:02 ` [Bug inline-asm/39543] " jakub at gcc dot gnu dot org
2009-04-26 18:56 ` jakub at gcc dot gnu dot org
2009-04-26 18:58 ` jakub at gcc dot gnu dot org
2009-04-26 19:09 ` jakub at gcc dot gnu dot org
2009-05-01 13:15 ` pinskia at gcc dot gnu dot org
2009-05-07 22:18 ` pinskia at gcc dot gnu dot org
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