Added --with-sse2 configure flag for SSE2 heuristic optimizations

configure.ac

@@ -122,6 +122,17 @@ AC_C_BIGENDIAN(
 	AC_DEFINE(ENDIAN_LITTLE, 1, [Little endian]),
 	AC_MSG_ERROR([Can't determine endianness]) )
 
+# If we're compiling with the SSE2 build flag, add that flag to CFLAGS and CXXFLAGS.
+# (Handwritten SSE/SSE2 code isn't in the binary, but GCC's heuristics optimize enough
+# vector arithmetic in Rage that this produces a noticeable speedup on SSE2 processors.)
+
+AC_ARG_WITH(sse2, AC_HELP_STRING([--with-sse2], [Enable SSE2 optimization]), with_sse2=$withval, with_sse2=no)
+
+if test "$with_sse2" = "yes"; then
+	CFLAGS="$CFLAGS -msse2"
+	CXXFLAGS="$CXXFLAGS -msse2"
+fi
+
 AC_ARG_WITH(prof, AS_HELP_STRING([--with-prof],[Enable profiling]), with_prof=$withval, with_prof=no)
 if test "$with_prof" = "yes"; then
 	test "$DEFAULT_CFLAGS" = "yes" && CFLAGS="$CFLAGS -pg"