Adds a --enable-lto option (Link Time Optimization)

Author: zwoop

configure.ac

@@ -233,6 +233,17 @@ AC_ARG_ENABLE([tsan],
 )
 AC_MSG_RESULT([$enable_tsan])
 
+#
+# Enable Link Time Optimization. This may need different settings per compiler?
+#
+AC_MSG_CHECKING([whether to enable LTO])
+AC_ARG_ENABLE([lto],
+  [AS_HELP_STRING([--enable-lto],[turn on Link Time Optomization])],
+  [],
+  [enable_lto=no]
+)
+AC_MSG_RESULT([$enable_lto])
+
 #
 # Fast SDK APIs, this disables the parameter checks (assert)
 # on all APIs.
@@ -938,6 +949,13 @@ AS_IF([test x"$enable_werror" = "xyes"], [
   TS_ADDTO(debug_opt, -Werror)
 ])
 
+# Add the necessary flags for LTO, but only for release builds
+AS_IF([test x"$enable_lto" = "xyes"], [
+  TS_ADDTO(AM_CXXFLAGS, "-flto")
+  TS_ADDTO(AM_CFLAGS, "-flto")
+  TS_ADDTO(AM_LDFLAGS, "-flto")
+])
+
 cc_oflag_opt=$release_opt
 cc_oflag_dbg=$debug_opt
 cxx_oflag_opt="$release_opt $cxx_opt $cxx_rel"