[Emacs-diffs] emacs-24 r117269: * configure.ac: Warn about --enable-link-time-optimization's issues

[Paul Eggert]

------------------------------------------------------------
revno: 117269
revision-id: address@hidden
parent: address@hidden
fixes bug: http://debbugs.gnu.org/17806
committer: Paul Eggert <address@hidden>
branch nick: emacs-24
timestamp: Fri 2014-06-20 12:46:18 -0700
message:
  * configure.ac: Warn about --enable-link-time-optimization's issues
  
  in --help message.
modified:
  ChangeLog                      changelog-20091113204419-o5vbwnq5f7feedwu-1538
  configure.ac                   
configure.in-20091113204419-o5vbwnq5f7feedwu-783

=== modified file 'ChangeLog'
--- a/ChangeLog 2014-06-20 06:07:47 +0000
+++ b/ChangeLog 2014-06-20 19:46:18 +0000
@@ -1,5 +1,8 @@
 2014-06-20  Paul Eggert  <address@hidden>
 
+       * 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

=== modified file 'configure.ac'
--- a/configure.ac      2014-06-20 06:07:47 +0000
+++ b/configure.ac      2014-06-20 19:46:18 +0000
@@ -757,7 +757,10 @@
 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