Commit 81e5c6fc authored by Paul Eggert's avatar Paul Eggert

* configure.ac: Warn about --enable-link-time-optimization's issues

in --help message.

Fixes: debbugs:17806
parent f49b4978
2014-06-20 Paul Eggert <eggert@cs.ucla.edu>
* configure.ac: Warn about --enable-link-time-optimization's issues
in --help message (Bug#17806).
Port to GCC 4.9.0 with link time optimization (Bug#17806).
* configure.ac (CFLAGS): With link time optimization,
use -ffat-lto-objects if supported; otherwise Emacs won't
......
......@@ -757,7 +757,10 @@ AC_ARG_ENABLE([gcc-warnings],
AC_ARG_ENABLE(link-time-optimization,
[AS_HELP_STRING([--enable-link-time-optimization],
[build emacs with link-time optimization.
This is supported only for GCC since 4.5.0.])],
This requires GCC 4.5.0 or later.
It also makes Emacs harder to debug, and when we tried it
with GCC 4.9.0 x86-64 it made Emacs slower, so it's not
recommended for typical use.])],
if test "${enableval}" != "no"; then
AC_MSG_CHECKING([whether link-time optimization is supported])
ac_lto_supported=no
......
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