Enable LTO by default.

LTO for Windows is disabled for now, as TDM-GCC does not work well with it.
LTO for Travis is also disabled, due to the extra time linking with LTO takes.

.travis.yml

@@ -57,7 +57,7 @@ script:
           ./utils/travis/check_utf8.sh;
           ./utils/travis/utf8_bom_dog.sh;
           "$CXX" --version;
-          scons wesnoth wesnothd campaignd boost_unit_tests build=release ctool="$CC" cxxtool="$CXX" --debug=time extra_flags_config="-pipe" extra_flags_release="$EXTRA_FLAGS_RELEASE" strict=true cxx_std="$CXXSTD" nls="$NLS" jobs=2;
+          scons wesnoth wesnothd campaignd boost_unit_tests build=release ctool="$CC" cxxtool="$CXX" --debug=time extra_flags_config="-pipe" extra_flags_release="$EXTRA_FLAGS_RELEASE" strict=true cxx_std="$CXXSTD" nls="$NLS" jobs=2 enable_lto=false;
       else
           export DISPLAY=:99.0;
           /sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1024x768x24;

CMakeLists.txt

@@ -151,10 +151,14 @@ option(ENABLE_STRICT_COMPILATION "Sets the strict compilation mode" OFF)
 option(ENABLE_PEDANTIC_COMPILATION "Sets the pedantic compilation mode" OFF)
 option(ENABLE_DEBUG_WINDOW_LAYOUT "Add the debug option to allow the generation of debug layout files in dot format" OFF)
 option(ENABLE_DESIGN_DOCUMENTS "Enables the generation of design documents, and has additional dependencies" OFF)
-option(ENABLE_LTO "Sets Link Time Optimization for Release builds" OFF)
+option(ENABLE_LTO "Sets Link Time Optimization for Release builds" ON)
 option(GLIBCXX_DEBUG "Whether to define _GLIBCXX_DEBUG and _GLIBCXX_DEBUG_PEDANTIC" OFF)
 option(ENABLE_POT_UPDATE_TARGET "Enables the tools to update the pot files and manuals. This target has extra dependencies." OFF)
 
+if(WIN32)
+	set(ENABLE_LTO OFF)
+endif(WIN32)
+
 if(UNIX AND NOT APPLE AND NOT CYGWIN)
 	option(ENABLE_NOTIFICATIONS "Enable Window manager notification messages" ON)
 endif(UNIX AND NOT APPLE AND NOT CYGWIN)

SConstruct

@@ -53,7 +53,7 @@ opts.AddVariables(
     ('extra_flags_release', 'Extra compiler and linker flags to use for release builds', ""),
     ('extra_flags_debug', 'Extra compiler and linker flags to use for debug builds', ""),
     ('extra_flags_profile', 'Extra compiler and linker flags to use for profile builds', ""),
-    BoolVariable('enable_lto', 'Whether to enable Link Time Optimization for build=release', False),
+    BoolVariable('enable_lto', 'Whether to enable Link Time Optimization for build=release', True),
     ('arch', 'What -march option to use for build=release, will default to pentiumpro on Windows', ""),
     BoolVariable('glibcxx_debug', 'Whether to define _GLIBCXX_DEBUG and _GLIBCXX_DEBUG_PEDANTIC for build=debug', False),
     EnumVariable('profiler', 'profiler to be used for build=profile', "gprof", ["gprof", "gcov", "gperftools", "perf"]),
@@ -504,6 +504,10 @@ for env in [test_env, client_env, env]:
 # Start setting options for release build
 # #
 
+# disable LTO for Windows only - does not work with TDM-GCC
+        if env["PLATFORM"] == "win32":
+            env["enable_lto"] = False
+
 # default compiler flags
         rel_comp_flags = "-O3"
         rel_link_flags = ""

docker_run.sh

@@ -49,9 +49,9 @@ if [ "$NLS" == "true" ]; then
 else
 # if not doing the translations, build wesnoth, wesnothd, campaignd, boost_unit_tests
   if [ "$TOOL" == "cmake" ]; then
-    cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GAME=true -DENABLE_SERVER=true -DENABLE_CAMPAIGN_SERVER=true -DENABLE_TESTS=true -DENABLE_NLS=false -DEXTRA_FLAGS_CONFIG="-pipe" -DEXTRA_FLAGS_RELEASE="$EXTRA_FLAGS_RELEASE" -DENABLE_STRICT_COMPILATION="$STRICT" && make VERBOSE=1 -j2
+    cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GAME=true -DENABLE_SERVER=true -DENABLE_CAMPAIGN_SERVER=true -DENABLE_TESTS=true -DENABLE_NLS=false -DEXTRA_FLAGS_CONFIG="-pipe" -DEXTRA_FLAGS_RELEASE="$EXTRA_FLAGS_RELEASE" -DENABLE_STRICT_COMPILATION="$STRICT" -DENABLE_LTO=false && make VERBOSE=1 -j2
   else
-    scons wesnoth wesnothd campaignd boost_unit_tests build=release ctool=$CC cxxtool=$CXX --debug=time extra_flags_config="-pipe" extra_flags_release="$EXTRA_FLAGS_RELEASE" strict="$STRICT" cxx_std=$CXXSTD nls=false jobs=2
+    scons wesnoth wesnothd campaignd boost_unit_tests build=release ctool=$CC cxxtool=$CXX --debug=time extra_flags_config="-pipe" extra_flags_release="$EXTRA_FLAGS_RELEASE" strict="$STRICT" cxx_std=$CXXSTD nls=false jobs=2 enable_lto=false
   fi
 
 # check if the build was successful