enable using link-time optimization

This commit enables LTO for all shared libraries.
Build takes much longer. Use just with gcc-4.5 or later.

1 files changed, 19 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index 536ca8ba5e27..87522f7ac525 100755
--- a/configure.in
+++ b/configure.in
@@ -244,6 +244,13 @@ AC_ARG_ENABLE(dbgutil,
         [Include additional debugging utilities, such as assertions, object
          counting, etc. Larger build. Independent from --enable-debug]))
 
+AC_ARG_ENABLE(lto,
+    AS_HELP_STRING([--enable-lto],
+        [Enable link-time optimization. Suitable for product builds.
+         Building takes longer but libraries are optimized for speed.
+         (possible only with gcc-4.5 or later,
+          better to use gcc-4.6 and 'gold' as linker)]))
+
 AC_ARG_ENABLE(crashdump,
     AS_HELP_STRING([--enable-crashdump],
         [Enable the crashdump feature.]))
@@ -2229,6 +2236,18 @@ AC_SUBST(PRODUCT)
 AC_SUBST(PROFULLSWITCH)
 AC_SUBST(PROEXT)
 
+# Set the ENABLE_LTO variable
+# ===================================================================
+AC_MSG_CHECKING([whether to use link-time optimization])
+if test -n "$enable_lto" -a "$enable_lto" != "no"; then
+    ENABLE_LTO="TRUE"
+    AC_MSG_RESULT([yes])
+else
+    ENABLE_LTO=""
+    AC_MSG_RESULT([no])
+fi
+AC_SUBST(ENABLE_LTO)
+
 dnl whether to include symbols into final build.
 dnl ===================================================================
 AC_MSG_CHECKING([whether to include symbols])