build: Use -Bsymbolic-functions by default if available

While we have much larger performance problems right now, using
-Bsymbolic-functions to avoid internal PLT indirection is an easy win.

This is the same code that both GLib and GTK+ have.

https://bugzilla.gnome.org/show_bug.cgi?id=689456

diff --git a/Makefile-girepository.am b/Makefile-girepository.am
index eb55a54..11549d4 100644 (file)
--- a/Makefile-girepository.am
+++ b/Makefile-girepository.am
@@ -72,7 +72,10 @@ libgirepository_1_0_la_SOURCES =                     \
 
 libgirepository_1_0_la_CPPFLAGS = $(GIREPO_CFLAGS) -I$(top_srcdir)/girepository -DG_IREPOSITORY_COMPILATION
 libgirepository_1_0_la_LIBADD = libgirepository-gthash.la $(GIREPO_LIBS)
-libgirepository_1_0_la_LDFLAGS = -no-undefined -version-number 1:0:0 -export-symbols $(srcdir)/girepository/girepository.symbols
+libgirepository_1_0_la_LDFLAGS = \
+       $(EXTRA_LINK_FLAGS) \
+       -no-undefined -version-number 1:0:0 \
+       -export-symbols $(srcdir)/girepository/girepository.symbols
 
 gdumpdir = $(datadir)/gobject-introspection-1.0/
 gdump_DATA = girepository/gdump.c

diff --git a/configure.ac b/configure.ac
index 74a44de..b1e8ea9 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -287,7 +287,28 @@ AM_CONDITIONAL(WITH_GLIBSRC, test x"$GLIBSRC" != x)
 AC_SUBST(GLIBSRC)
 AC_MSG_RESULT([$GLIBSRC])
 
+dnl
+dnl Check for -Bsymbolic-functions linker flag used to avoid
+dnl intra-library PLT jumps, if available.
+dnl
+AC_ARG_ENABLE(Bsymbolic,
+              [AS_HELP_STRING([--disable-Bsymbolic],
+                              [avoid linking with -Bsymbolic])],,
+              [SAVED_LDFLAGS="${LDFLAGS}"
+               AC_MSG_CHECKING([for -Bsymbolic-functions linker flag])
+               LDFLAGS=-Wl,-Bsymbolic-functions
+               AC_TRY_LINK([], [int main (void) { return 0; }],
+                           AC_MSG_RESULT(yes)
+                           enable_Bsymbolic=yes,
+                           AC_MSG_RESULT(no)
+                           enable_Bsymbolic=no)
+               LDFLAGS="${SAVED_LDFLAGS}"])
+
+if test "x${enable_Bsymbolic}" = "xyes"; then
+  EXTRA_LINK_FLAGS=-Wl,-Bsymbolic-functions
+fi
 
+AC_SUBST(EXTRA_LINK_FLAGS)
 
 AC_CONFIG_FILES([
 Makefile