pass user/maintainer provided CXXFLAGS to the Scintilla build process

 * Usually, Scintilla will now be built with -O2
 * this can improve performance significantly over the standard Scintilla -Os
   (up to 10%).
 * this also allows link-time-optimizing both Scintilla and SciTECO
   (which are linked statically) by adding -flto to CFLAGS, CXXFLAGS and LDFLAGS.
   Link-time-optimization will both reduce the total binary size
   and improve performance slightly since scintilla_send_message() can be
   inlined.
   An -O3 optimized Scintilla when linked with LTO results in an only 300kb
   larger SciTECO binary.
 * the highest possible optimization thus requires the following maintainer
   flags on the ./configure command line:
   CFLAGS="-O3 -mtune=native -march=native -flto"
   CXXFLAGS="-O3 -mtune=native -march=native -flto"
   LDFLAGS="-flto"
 * Windows and Debian builds use link-time-optimization now.
   On Windows - where we link in everything statically - building
   the dependant libraries with -flto could improve performance
   even more.
 * Debian builds respect the default hardening flags of the build
   server now. This should ensure that SciTECO is built for the
   correct architecture at the recommended optimization level etc.

5 files changed, 22 insertions, 7 deletions

diff --git a/TODO b/TODO
index 1349d4d..94ef048 100644
--- a/TODO
+++ b/TODO
@@ -184,9 +184,6 @@ Features:
    Use Autotest for instance.
 
 Optimizations:
- * Support link-time-optimization for Scintilla and SciTECO.
-   This could significantly improve performance esp. when linking
-   in everything statically as is done on Windows.
  * Instead of using RTTI to implement the immediate editing command
    behaviours in Cmdline::process_edit_cmd() depending on the current
    state, this could be modelled via virtual methods in State.
diff --git a/configure.ac b/configure.ac
index d44689b..56e61c9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,6 +19,14 @@ AC_CONFIG_HEADERS([config.h])
 AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
 
+# Use the user provided CXXFLAGS for Scintilla as well.
+# This makes sure that the same optimizations are applied
+# to SciTECO and Scintilla.
+# We cannot pass CXXFLAGS directly to Scintilla since
+# we modify it during library checking.
+SCINTILLA_CXXFLAGS="$CXXFLAGS"
+AC_SUBST(SCINTILLA_CXXFLAGS)
+
 # Automake build flag substitutions.
 # Necessary so we can change their default values here
 AC_SUBST(AM_CPPFLAGS)
diff --git a/debian/rules b/debian/rules
index c8bea8d..7d6302c 100755
--- a/debian/rules
+++ b/debian/rules
@@ -12,6 +12,11 @@
 # build dependencies.
 export TERM=
 
+# Build with link-time-optimizations
+export DEB_CFLAGS_MAINT_APPEND=-flto
+export DEB_CXXFLAGS_MAINT_APPEND=-flto
+export DEB_LDFLAGS_MAINT_APPEND=-flto
+
 %:
 	dh $@
 
@@ -19,7 +24,8 @@ build:
 	dh_testdir
 	dh_auto_configure -- \
 			  --enable-bootstrap \
-			  --with-interface=ncurses
+			  --with-interface=ncurses \
+	                  $(shell dpkg-buildflags --export=configure)
 	dh_auto_build
 	touch $@
 
diff --git a/distribute b/distribute
index 24f9494..d8304dc 100755
--- a/distribute
+++ b/distribute
@@ -111,7 +111,8 @@ sciteco-$(SCITECO_VERSION)-win32.zip : $(SCITECO_SRC)
 		     --with-interface=$(MINGW_UI) \
 		     --disable-bootstrap \
 		     --enable-html-manual \
-		     CFLAGS="-g -O3" CXXFLAGS="-g -O3"; \
+		     CFLAGS="-g -O3 -flto" CXXFLAGS="-g -O3 -flto"; \
+	             LDFLAGS="-flto" \
 	)
 	$(MAKE) -C sciteco-$(SCITECO_VERSION) \
 		install-strip DESTDIR=`pwd`/temp-install
diff --git a/scintilla.am b/scintilla.am
index df340bf..c9cf4c6 100644
--- a/scintilla.am
+++ b/scintilla.am
@@ -4,10 +4,13 @@
 
 if INTERFACE_GTK
 MAKE_SCINTILLA = $(MAKE) -C @SCINTILLA_PATH@/gtk \
-                 GTK3=yes CONFIGFLAGS='@LIBGTK_CFLAGS@'
+                 GTK3=yes CONFIGFLAGS='@LIBGTK_CFLAGS@' \
+                 CXXFLAGS='@SCINTILLA_CXXFLAGS@'
 else
+# FIXME: There is currently no way to override the standard optimization
+# flags of Scinterm, so we pass them in CURSES_FLAGS.
 MAKE_SCINTILLA = $(MAKE) -C @SCINTERM_PATH@ \
-                 CURSES_FLAGS='@PDCURSES_CFLAGS@ @XCURSES_CFLAGS@ @NCURSES_CFLAGS@'
+                 CURSES_FLAGS='@PDCURSES_CFLAGS@ @XCURSES_CFLAGS@ @NCURSES_CFLAGS@ @SCINTILLA_CXXFLAGS@'
 endif
 
 # Pass toolchain configuration to Scintilla.