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Re: Faster compilation speed
- From: Neil Booth <neil at daikokuya dot co dot uk>
- To: Stan Shebs <shebs at apple dot com>
- Cc: Noel Yap <yap_noel at yahoo dot com>, Mike Stump <mrs at apple dot com>,gcc at gcc dot gnu dot org
- Date: Fri, 9 Aug 2002 23:16:20 +0100
- Subject: Re: Faster compilation speed
- References: <email@example.com> <3D543E54.firstname.lastname@example.org>
Stan Shebs wrote:-
> Is this assertion based on empirical measurement, and if so, for what
> source code and what system? For instance, the longest source file
> in GCC is about 15K lines, and at -O2, only a small percentage of
> time is spent messing with files. If I use -save-temps on cp/decl.c on
> one of my (Linux) machines, I get a total time of about 38 sec from
> source to asm. If I just compile decl.i, it's about 37 sec, so that's
> 1 sec for *all* preprocessing, including all file opening/closing.
Yes, it's very rare that preprocessing is more than 2% of -O2 time;
it's often less than 1%. IMO that says more about the efficiency
of the rest than of CPP.