From: Mark Mitchell <mark@codesourcery.com>
To: Peter Barada <peter@the-baradas.com>
Cc: nathan@codesourcery.com, richard.guenther@gmail.com,
stevenb@suse.de, joseph@codesourcery.com,
ian@wasabisystems.com, gcc@gcc.gnu.org
Subject: Re: Compiler uses a lot of memory for large initialized arrays
Date: Thu, 02 Dec 2004 17:39:00 -0000 [thread overview]
Message-ID: <41AF5335.50509@codesourcery.com> (raw)
In-Reply-To: <20041202172949.9C1119842C@baradas.org>
Peter Barada wrote:
>>>Or can't we seek in the asm output and overwrite previously written values?
>>>Might be slow, though.
>>
>>Even if that were sensible, where will we remember the file offsets
>>of each and every element :)
I think overwriting stuff in the assembler is a horrible idea.
I also think that trying to acheive 2.95.3 memory usage for huge arrays
is foolish. Since then, we've deliberately substantially increased the
amount of memory we need for lots of things: function-at-a-time is more
expensive than statement-at-a-time, and now we're unit-at-a-time for
many compilations -- as we should be. Most compilers suck up lots of
memory with vast arrays; I don't think we need to be different, alleged
regression or not.
However, the C++ front end (and perhaps the C front end) do some pretty
silly stuff when contstructing the arrays. I believe that when I
analyzed this, I determined that there were factor-of-eight sorts of
improvements possible. That's what I think we should fix.
We've already got some of that, in that, for example, Nathan's changed
things so that we share integer constants. The next major step is to
change CONSTRUCTOR to use an array, rather than a linked list, of
elements for CONSTRUCTOR_ELTS.
--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304
next prev parent reply other threads:[~2004-12-02 17:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-02 16:08 Ian Lance Taylor
2004-12-02 16:34 ` Joseph S. Myers
2004-12-02 17:03 ` Ian Lance Taylor
2004-12-02 17:05 ` Steven Bosscher
2004-12-02 17:12 ` Richard Guenther
2004-12-02 17:17 ` Nathan Sidwell
2004-12-02 17:29 ` Peter Barada
2004-12-02 17:39 ` Mark Mitchell [this message]
2004-12-02 17:42 ` Ian Lance Taylor
2004-12-02 17:49 ` Dave Korn
2004-12-02 17:36 ` Andreas Schwab
2004-12-02 18:18 ` Joe Buck
2004-12-02 18:23 ` Mark Mitchell
2004-12-02 17:31 ` Mark Mitchell
2004-12-02 17:33 ` Giovanni Bajo
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