check for __builtin_expect (used by libmpeg2)

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@14015 b3059339-0415-0410-9bf9-f77b7e298cf2

1 files changed, 22 insertions, 0 deletions

diff --git a/configure b/configure
index efad5d2507..d5ac8632aa 100755
--- a/configure
+++ b/configure
@@ -2309,6 +2309,25 @@ else
 fi
 
 
+echocheck "__builtin_expect"
+# GCC branch prediction hint
+cat > $TMPC << EOF
+int foo (int a) {
+    a = __builtin_expect (a, 10);
+    return a == 10 ? 0 : 1;
+}
+int main() { return foo(10) && foo(0); }
+EOF
+_builtin_expect=no
+cc_check && _builtin_expect=yes
+if test "$_builtin_expect" = yes ; then
+  _def_builtin_expect='#define HAVE_BUILTIN_EXPECT 1'
+else
+  _def_builtin_expect='#undef HAVE_BUILTIN_EXPECT'
+fi
+echores "$_builtin_expect"
+
+
 echocheck "kstat"
 cat > $TMPC << EOF
 #include <kstat.h>
@@ -6672,6 +6691,9 @@ $_def_dynamic_plugins
 /* "restrict" keyword */
 $_def_restrict_keyword
 
+/* __builtin_expect branch prediction hint */
+$_def_builtin_expect
+
 /* attribute(used) as needed by some compilers */
 #if (__GNUC__ * 100 + __GNUC_MINOR__ >= 300)
 # define attribute_used __attribute__((used))