* configure.ac (--enable-link-time-optimization): Add clang support.
* INSTALL: Mention it. * etc/PROBLEMS: Mention potential problems with --enable-link-time-optimization and clang on Fedora 20.
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Dmitry Antipov
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5 changed files with 80 additions and 33 deletions
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@ -1,3 +1,8 @@
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2014-05-13 Dmitry Antipov <dmantipov@yandex.ru>
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* configure.ac (--enable-link-time-optimization): Add clang support.
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* INSTALL: Mention it.
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2014-05-12 Katsumi Yamaoka <yamaoka@jpl.org>
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* configure.ac (EMACS_CHECK_MODULES): Fix typo in previous change.
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17
INSTALL
17
INSTALL
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@ -331,12 +331,17 @@ and is useful with GNU-compatible compilers. On a recent GNU system
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there should be no warnings; on older and on non-GNU systems the
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generated warnings may still be useful.
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Use --enable-link-time-optimization to enable link-time optimizer, which
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is available in GNU compiler since version 4.5.0. If your compiler is not
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GNU or older than version 4.5.0, this option does nothing. If `configure'
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can determine number of online CPUS on your system, final link-time
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optimization and code generation is executed in parallel using one job
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per each available online CPU.
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Use --enable-link-time-optimization to enable link-time optimizer. If
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you're using GNU compiler, this feature is supported since version 4.5.0.
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If `configure' can determine number of online CPUS on your system, final
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link-time optimization and code generation is executed in parallel using
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one job per each available online CPU.
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This option is also supported for clang. You should have GNU binutils
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with `gold' linker and plugin support, and clang with LLVMgold.so plugin.
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Read http://llvm.org/docs/GoldPlugin.html for details. Also note that
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this feature is still experimental, so prepare to build binutils and
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clang from the corresponding source code repositories.
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The `--prefix=PREFIXDIR' option specifies where the installation process
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should put emacs and its data files. This defaults to `/usr/local'.
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72
configure.ac
72
configure.ac
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@ -762,32 +762,6 @@ AC_ARG_ENABLE([gcc-warnings],
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[gl_gcc_warnings=no]
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)
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AC_ARG_ENABLE(link-time-optimization,
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[AS_HELP_STRING([--enable-link-time-optimization],
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[build emacs with link-time optimization.
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This is supported only for GCC since 4.5.0.])],
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if test "${enableval}" != "no"; then
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AC_MSG_CHECKING([whether link-time optimization is supported])
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ac_lto_supported=no
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if test x$GCC = xyes; then
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CPUS=`getconf _NPROCESSORS_ONLN 2>/dev/null`
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if test x$CPUS != x; then
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LTO="-flto=$CPUS"
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else
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LTO="-flto"
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fi
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old_CFLAGS=$CFLAGS
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CFLAGS="$CFLAGS $LTO"
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
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[ac_lto_supported=yes], [ac_lto_supported=no])
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CFLAGS="$old_CFLAGS"
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fi
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AC_MSG_RESULT([$ac_lto_supported])
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if test "$ac_lto_supported" = "yes"; then
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CFLAGS="$CFLAGS $LTO"
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fi
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fi)
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# clang is unduly picky about some things.
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AC_CACHE_CHECK([whether the compiler is clang], [emacs_cv_clang],
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[AC_COMPILE_IFELSE(
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@ -913,7 +887,51 @@ edit_cflags="
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s/^ //
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"
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AC_ARG_ENABLE(link-time-optimization,
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[AS_HELP_STRING([--enable-link-time-optimization],
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[build emacs with link-time optimization.
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This is supported for gcc since 4.5.0 and clang.
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Note that clang support is experimental - see INSTALL])],
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if test "${enableval}" != "no"; then
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ac_lto_supported=no
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if test $emacs_cv_clang = yes; then
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AC_MSG_CHECKING([whether link-time optimization is supported by clang])
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GOLD_PLUGIN=`$CC -print-file-name=LLVMgold.so 2>/dev/null`
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if test -x "$GOLD_PLUGIN"; then
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LTO="-flto"
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fi
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elif test x$GCC = xyes; then
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AC_MSG_CHECKING([whether link-time optimization is supported by gcc])
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CPUS=`getconf _NPROCESSORS_ONLN 2>/dev/null`
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if test x$CPUS != x; then
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LTO="-flto=$CPUS"
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else
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LTO="-flto"
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fi
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else
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AC_MSG_ERROR([Link-time optimization is not supported with your compiler.])
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fi
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if test -z "$LTO"; then
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ac_lto_supported=no
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else
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old_CFLAGS=$CFLAGS
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CFLAGS="$CFLAGS $LTO"
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
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[ac_lto_supported=yes], [ac_lto_supported=no])
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CFLAGS="$old_CFLAGS"
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fi
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AC_MSG_RESULT([$ac_lto_supported])
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if test "$ac_lto_supported" = "yes"; then
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CFLAGS="$CFLAGS $LTO"
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if test x$emacs_cv_clang = xyes; then
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AC_MSG_WARN([Please read INSTALL before using link-time optimization with clang])
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# WARNING: 'ar --plugin ...' doesn't work without
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# command, so plugin name is appended to ARFLAGS.
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ARFLAGS="cru --plugin $GOLD_PLUGIN"
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RANLIB="$RANLIB --plugin $GOLD_PLUGIN"
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fi
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fi
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fi)
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dnl Some other nice autoconf tests.
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dnl These are commented out, since gl_EARLY and/or Autoconf already does them.
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@ -1,3 +1,8 @@
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2014-05-13 Dmitry Antipov <dmantipov@yandex.ru>
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* PROBLEMS: Mention potential problems with
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--enable-link-time-optimization and clang on Fedora 20.
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2014-05-04 Leo Liu <sdl.web@gmail.com>
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* NEWS: Mention support for Chinese dates in calendar and diary.
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14
etc/PROBLEMS
14
etc/PROBLEMS
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@ -836,6 +836,20 @@ you want to use fcitx with Emacs, you have two choices. Toggle fcitx
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by another key (e.g. C-\) by modifying ~/.fcitx/config, or be
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accustomed to use C-@ for `set-mark-command'.
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*** Link-time optimization with clang doesn't work on Fedora 20.
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As of May 2014, Fedora 20 has broken LLVMgold.so plugin support in clang
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(tested with clang-3.4-6.fc20) - `clang --print-file-name=LLVMgold.so'
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prints `LLVMgold.so' instead of full path to plugin shared library, and
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`clang -flto' is unable to find the plugin with the following error:
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/bin/ld: error: /usr/bin/../lib/LLVMgold.so: could not load plugin library:
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/usr/bin/../lib/LLVMgold.so: cannot open shared object file: No such file
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or directory
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The only way to avoid this is to build your own clang from source code
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repositories, as described at http://clang.llvm.org/get_started.html.
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*** M-SPC seems to be ignored as input.
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See if your X server is set up to use this as a command
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