* 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.

1 files changed, 11 insertions, 6 deletions

diff --git a/INSTALL b/INSTALL
index 496c6c8c376..3502631cbcf 100644
--- a/INSTALL
+++ b/INSTALL
@@ -331,12 +331,17 @@ and is useful with GNU-compatible compilers.  On a recent GNU system
 there should be no warnings; on older and on non-GNU systems the
 generated warnings may still be useful.
 
-Use --enable-link-time-optimization to enable link-time optimizer, which
-is available in GNU compiler since version 4.5.0.  If your compiler is not
-GNU or older than version 4.5.0, this option does nothing.  If `configure'
-can determine number of online CPUS on your system, final link-time
-optimization and code generation is executed in parallel using one job
-per each available online CPU.
+Use --enable-link-time-optimization to enable link-time optimizer.  If
+you're using GNU compiler, this feature is supported since version 4.5.0.
+If `configure' can determine number of online CPUS on your system, final
+link-time optimization and code generation is executed in parallel using
+one job per each available online CPU.
+
+This option is also supported for clang.  You should have GNU binutils
+with `gold' linker and plugin support, and clang with LLVMgold.so plugin.
+Read http://llvm.org/docs/GoldPlugin.html for details.  Also note that
+this feature is still experimental, so prepare to build binutils and
+clang from the corresponding source code repositories.
 
 The `--prefix=PREFIXDIR' option specifies where the installation process
 should put emacs and its data files.  This defaults to `/usr/local'.