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From: Paul Koning <pkoning@equallogic.com>
To: mark@codesourcery.com
Cc: ebotcazou@act-europe.fr, gcc@gcc.gnu.org
Subject: Re: GCC Status Report (2004-03-09)
Date: Tue, 16 Mar 2004 16:59:00 -0000	[thread overview]
Message-ID: <16471.12911.55000.733792@gargle.gargle.HOWL> (raw)
In-Reply-To: <40573108.4080602@codesourcery.com>

>>>>> "Mark" == Mark Mitchell <mark@codesourcery.com> writes:

 Mark> The other alternative I can think of is to introduce a
 Mark> scheduling barrier (e.g., a dummy vaolatile asm) after the
 Mark> clearing operation. 

It would be nice if there were a clearly documented way to do that.

I've found two:

     asm("")
     asm("":::"memory")

The former does what I want but isn't documented and (according to
what I was told) should NOT be counted on to be a barrier.

The latter is documented and does a superset of what I needed at the
time.  I say "superset" because it causes registers to be reloaded
with data from variables (due to the memory clobber).  That's a
performance hit if I didn't have any real memory clobbers in the
system.

Perhaps we need asm("":::"barrier")?

	paul

  reply	other threads:[~2004-03-16 16:59 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-03-09 18:09 Mark Mitchell
2004-03-11  9:45 ` Eric Botcazou
2004-03-11 12:48   ` Jakub Jelinek
2004-03-11 21:11     ` Richard Henderson
2004-03-16 16:53   ` Mark Mitchell
2004-03-16 16:59     ` Paul Koning [this message]
2004-03-16 17:11       ` Ian Lance Taylor
2004-03-16 17:24         ` Zack Weinberg
2004-03-16 17:25           ` Paul Koning
2004-03-17 10:56     ` Eric Botcazou
2004-03-17 11:49       ` Eric Botcazou
2004-03-17 15:55       ` Mark Mitchell
2004-03-18  8:25         ` Eric Botcazou
2004-03-18 18:31           ` Eric Botcazou
2004-03-18 19:15             ` Mark Mitchell
2004-03-18 23:36               ` Eric Botcazou
2004-03-18 23:41                 ` Jakub Jelinek
2004-03-19  1:23                   ` Eric Botcazou
2004-03-19 14:31                   ` Eric Botcazou
2004-03-19 19:29                     ` Mark Mitchell
2004-03-19 20:04                       ` Eric Botcazou
2004-03-19 20:23                         ` Mark Mitchell
2004-03-20 19:51                           ` Eric Botcazou
     [not found]                 ` <405A3F26.2050100@codesourcery.com>
     [not found]                   ` <200403190155.18981.ebotcazou@libertysurf.fr>
2004-03-19  6:42                     ` Mark Mitchell
2004-03-16  2:09 ` C++ status (Was: GCC Status Report (2004-03-09)) Giovanni Bajo
2004-03-11 12:15 GCC Status Report (2004-03-09) Richard Kenner
2004-03-11 12:39 ` Eric Botcazou
2004-03-11 12:49 Richard Kenner
2004-03-11 14:09 ` Eric Botcazou
2004-03-19  6:34 Richard Kenner
2004-03-19 12:18 ` Jakub Jelinek
2004-03-19 14:22 Richard Kenner
2004-03-19 20:08 Richard Kenner

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