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Re: PATCH C++: speed up templates

From: Mark Mitchell <mark at codesourcery dot com>
To: Ziemowit Laski <zlaski at apple dot com>
Cc: Matt Austern <austern at apple dot com>, Mike Stump <mrs at apple dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Date: Wed, 19 Feb 2003 13:38:44 -0800
Subject: Re: PATCH C++: speed up templates

--On Wednesday, February 19, 2003 12:29:31 PM -0800 Ziemowit Laski <zlaski at apple dot com> wrote:

I was not aware

of this functionality (and, it would appear, neither was Mark) until
Devang pointed it out to me yesterday.

I actually wrote walk_tree. :-)

The reason you can't use walk_tree_without_duplicates is given in for_each_template_parm. The addition of the hash table there is necessary both for correctness *and for compile-time performance* in some situations. The fact that it is not a win in other situations is a consequence of a broken design -- namely that we have to use for_each_template_parm in situations we should not.

Optimizing this at the low level is fine, but the real problems are further up the chain.

--
Mark Mitchell                mark at codesourcery dot com
CodeSourcery, LLC            http://www.codesourcery.com

References:
- Re: PATCH C++: speed up templates
  - From: Ziemowit Laski

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