From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: 17806@debbugs.gnu.org
Subject: bug#17806: 24.4.50; Branch emacs-24 fails to beuild on Debian
Date: Tue, 24 Jun 2014 09:27:50 -0700 [thread overview]
Message-ID: <53A9A706.70505@cs.ucla.edu> (raw)
In-Reply-To: <53A99196.3030308@yandex.ru>
Dmitry Antipov wrote:
> RedHat's compiler engineer claims that LTO has made substantial progress
> in gcc-4.9: http://vmakarov.fedorapeople.org/spec/2014/2014.html
Those comments say that GCC 4.9.0 compiles much faster than GCC 4.8.3
when LTO is used. And that's understandable: in 4.9.0, -flto defaults
to -fno-fat-lto-objects. Unfortunately, this is the change that broke
the Emacs build. Emacs has worked around the problem by compiling with
-ffat-lto-objects, but this negates the compile-time performance
advantage of 4.9.0.
4.9.0 has not made significant improvements in run-time performance over
4.8.3 when LTO is used, and for Emacs LTO has only minor (and sometimes
even negative) run-time performance improvements compared to non-LTO.
next prev parent reply other threads:[~2014-06-24 16:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-18 22:37 bug#17806: 24.4.50; Branch emacs-24 fails to beuild on Debian Manoj Srivastava
2014-06-19 2:56 ` Eli Zaretskii
2014-06-19 3:41 ` Glenn Morris
2014-06-19 6:35 ` Manoj Srivastava
2014-06-19 8:42 ` Dmitry Antipov
2014-06-19 17:22 ` Manoj Srivastava
2014-06-19 18:39 ` Sven Joachim
2014-06-20 6:17 ` Paul Eggert
2014-06-20 7:20 ` Eli Zaretskii
2014-06-20 7:56 ` Paul Eggert
2014-06-20 8:15 ` Eli Zaretskii
2014-06-20 17:15 ` Glenn Morris
2014-06-20 19:48 ` Paul Eggert
2014-06-20 21:06 ` Stefan Monnier
2014-06-20 23:55 ` Paul Eggert
2014-06-21 12:54 ` Stefan Monnier
2014-06-21 3:46 ` Dmitry Antipov
2014-06-21 19:58 ` Glenn Morris
2014-06-24 14:56 ` Dmitry Antipov
2014-06-24 16:27 ` Paul Eggert [this message]
2014-06-24 16:39 ` Eli Zaretskii
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