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Re: GCC 3.3 compile speed regression - AN ANSWER
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- To: Matt Austern <austern at apple dot com>
- Cc: Linus Torvalds <torvalds at transmeta dot com>, <gcc at gcc dot gnu dot org>
- Date: Wed, 12 Feb 2003 07:52:35 +0000 (GMT)
- Subject: Re: GCC 3.3 compile speed regression - AN ANSWER
On Tue, 11 Feb 2003, Matt Austern wrote:
> All of my measurements suggest that improving the speed of optimization
> phases is irrelevant. What's slow is the front end: parsing and
> semantic analysis. -O0 compilations are slow, not just -O3.
The -fsyntax-only figures posted
<http://gcc.gnu.org/ml/gcc/2003-02/msg00488.html> show it is not the front
end; -O0 -fsyntax-only has become faster, while the time for unoptimized
code generation (the time for -O0 minus that for -O0 -fsyntax-only) has
doubled between 2.95 branch and mainline and the times to optimize have
become worse as well. (This is for the C front end.) (In absolute terms,
the front end may still count as slow, but not if what you're comparing
with is GCC 2.95.)
--
Joseph S. Myers
jsm28@cam.ac.uk