add PHP_LTO='n'

- disabled by default for now due to bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68384

centmin.sh

@@ -315,6 +315,7 @@ GENERAL_DEVTOOLSETGCC='n'     # Use devtoolset-4 GCC 5.3 whereever possible/code
 CRYPTO_DEVTOOLSETGCC='n'      # Use devtoolset-4 GCC 5.3 for libressl or openssl compiles
 NGX_GSPLITDWARF='y'           # for Nginx compile https://community.centminmod.com/posts/44072/
 PHP_GSPLITDWARF='y'           # for PHP compile https://community.centminmod.com/posts/44072/
+PHP_LTO='n'                   # enable -flto compiler for GCC 4.8.5+ PHP-FPM compiles currently not working with PHP 7.x
 NGX_LDGOLD='y'                # for Nginx compile i.e. passing ld.gold linker -fuse-ld=bfd or -fuse-ld=gold https://community.centminmod.com/posts/44037/
 
 # When set to =y, will disable those listed installed services 

inc/php_configure.inc

@@ -518,8 +518,12 @@ if [[ "$GCCINTEL_PHP" = [yY] ]]; then
   gcc -c -Q -march=native --help=target | egrep '\[enabled\]|mtune|march|mfpmath' | tee -a ${CENTMINLOGDIR}/gcc_php_native.log
 
 
-  if [[ "$(gcc --version | head -n1 | awk '{print $3}' | cut -d . -f1-3 | sed "s|\.|0|g")" -ge '40805' && "$PHP_GSPLITDWARF" = [yY] ]]; then
+  if [[ "$(gcc --version | head -n1 | awk '{print $3}' | cut -d . -f1-3 | sed "s|\.|0|g")" -ge '40805' && "$PHP_GSPLITDWARF" = [yY] && "$PHP_LTO" = [yY] ]]; then
+    PHPEXTRA_CFLAGS="$PHPEXTRA_CFLAGS -gsplit-dwarf -flto -flto-partition=max"
+  elif [[ "$(gcc --version | head -n1 | awk '{print $3}' | cut -d . -f1-3 | sed "s|\.|0|g")" -ge '40805' && "$PHP_GSPLITDWARF" = [yY] && "$PHP_LTO" = [nN] ]]; then
     PHPEXTRA_CFLAGS="$PHPEXTRA_CFLAGS -gsplit-dwarf"
+  elif [[ "$(gcc --version | head -n1 | awk '{print $3}' | cut -d . -f1-3 | sed "s|\.|0|g")" -ge '40805' && "$PHP_LTO" = [yY] ]]; then
+    PHPEXTRA_CFLAGS="$PHPEXTRA_CFLAGS -flto -flto-partition=max"
   fi
 
 	if [[ "$(uname -m)" = 'x86_64' && "$CPUVENDOR" = 'GenuineIntel' && "$SSECHECK" = '[enabled]' ]] && [[ "$CLANG_PHP" = [nN] ]]; then