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RFC: Changing AC_DEFINE
From: |
Akim Demaille |
Subject: |
RFC: Changing AC_DEFINE |
Date: |
01 Jun 2001 17:12:05 +0200 |
User-agent: |
Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.1 (GTK) |
I would like to address the issues raised in
http://gcc.gnu.org/ml/gcc/2001-03/msg00814.html for 2.51. This
basically means try to use `echo' instead of a heredoc when there are
no funky characters.
Another idea that _might_ improve performances too would be to use a
fd for confdefs.h, just like for config.log. This raises two
questions:
1. what is the next fd we can use? Is 7 OK?
2. is it safe to use both an FD to confdefs.h and redirections to
confdefs.h?
Just for the record, the figures are quite impressive:
| Subject: Re: libstdc++ configure time
| From: Richard Henderson <rth at redhat dot com>
|
| I've hacked autoconf to use echo in a number of key places.
|
| With just AC_DEFINE, AC_DEFINE_UNQUOTED, and AC_TRY_LINK,
| the number of here documents is down from 485 to 156. This
| takes 16:20.3 to run configure on Solaris.
|
| Transforming AC_TRY_COMPILE, AC_TRY_CPP bring the number
| down to 29. A few more here and there bring us to 21.
| This takes 2:14.7 to run configure.
|
|
| r~
Note: I will _not_ use the solution they advocate (e.g., in
http://gcc.gnu.org/ml/gcc/2001-03/msg00975.html), but something based
on AC_VAR_IFELSE or so which will decide, case by case, whether echo
can be used, or whether heredocs should.
- RFC: Changing AC_DEFINE,
Akim Demaille <=