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From: Paolo Bonzini <bonzini@gnu.org>
To: Eric Botcazou <ebotcazou@adacore.com>
Cc: Paolo Bonzini <bonzini@gnu.org>,
	Andrew Pinski <pinskia@gmail.com>,
	  gcc-patches@gcc.gnu.org, Mark Mitchell <mark@codesourcery.com>
Subject: Re: PR/32004, tree-ssa caused in/out asm constraints to often need  reloads
Date: Mon, 09 Jul 2007 13:12:00 -0000	[thread overview]
Message-ID: <469231B2.3010503@gnu.org> (raw)
In-Reply-To: <200707091455.31718.ebotcazou@adacore.com>

Eric Botcazou wrote:
>> Actually it is fixed by this trivial patch.  Ok for 4.2/4.1?
> 
> This patch is *not* trivial.  The RTL dataflow engine in flow.c has known 
> quirks and we should be conservative in changing how it is invoked.

That's why I'm invoking in GLOBAL_RM_NOTES rather than LOCAL which ought 
to be enough.  That's conservativeness.

I do believe the patch is trivial (note I didn't say obvious) if you 
investigated the failure mode.  The problem is that reg_equiv_regs is 
set when REG_N_REFS is 2 and in this case we have more than 2 after the 
new pass.  The patch is in testing now, and the gcc directory has 
already been tested fully on both the 4.1 and 4.2 branches.

If you want me to revert the patch on 4.1 and apply the combination in a 
few days, after letting it stay on 4.2 for a while, I can do that. 
Otherwise, I would very much prefer fixing PR21291/PR32004, which is as 
bad a regression as the one I introduced.  Of course, I'm not meaning 
I'm *not* sorry to have introduced a regression.

Paolo

  parent reply	other threads:[~2007-07-09 13:01 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-05 10:54 Paolo Bonzini
     [not found] ` <84fc9c000707050401h46157b0fye4b32c3e6b1c8063@mail.gmail.com>
2007-07-05 11:48   ` Paolo Bonzini
2007-07-05 18:34 ` Mark Mitchell
2007-07-05 19:39   ` Paolo Bonzini
2007-07-05 20:24     ` Mark Mitchell
2007-07-05 20:15   ` Paolo Bonzini
2007-07-07 16:29 ` Eric Botcazou
2007-07-07 18:24   ` Andrew Pinski
2007-07-07 18:30     ` Eric Botcazou
2007-07-09  2:23       ` Paolo Bonzini
2007-07-09  6:52         ` Eric Botcazou
2007-07-09 12:09           ` Paolo Bonzini
2007-07-09 12:32           ` Paolo Bonzini
2007-07-09 12:40             ` Richard Guenther
2007-07-09 13:01             ` Eric Botcazou
2007-07-09 13:01               ` Richard Guenther
2007-07-09 13:36                 ` Eric Botcazou
2007-07-09 13:12               ` Paolo Bonzini [this message]
2007-07-09 13:23                 ` Andrew Pinski
2007-07-09 13:45                   ` Eric Botcazou
2007-07-09 15:33                   ` Paolo Bonzini
2007-07-09 17:25                     ` Eric Botcazou
2007-07-09 14:00                 ` Eric Botcazou
2007-07-13  9:48       ` Paolo Bonzini
2007-07-13 13:42         ` Eric Botcazou

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