mesa: Drop -fno-builtin-memcmp.

According to the referenced bug report, gcc-4.5 and newer do not inline
memcmp(). I see no difference in performance of ipers with llvmpipe on a
Sandybridge (which does not have "Enhanced REP MOVSB/STOSB") by removing
this flag.

I attempted to confirm the problem with gcc-4.4, but it fails to compile
for quite a few different reasons.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

diff --git a/configure.ac b/configure.ac
index 1ca8359..accd1a1 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -306,10 +306,6 @@ if test "x$GCC" = xyes; then
     # We don't want floating-point math functions to set errno or trap
     CFLAGS="$CFLAGS -fno-math-errno -fno-trapping-math"
 
-    # gcc's builtin memcmp is slower than glibc's
-    # http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43052
-    CFLAGS="$CFLAGS -fno-builtin-memcmp"
-
     # Flags to help ensure that certain portions of the code -- and only those
     # portions -- can be built with MSVC:
     # - src/util, src/gallium/auxiliary, rc/gallium/drivers/llvmpipe, and
@@ -348,10 +344,6 @@ if test "x$GXX" = xyes; then
 
     # Work around aliasing bugs - developers should comment this out
     CXXFLAGS="$CXXFLAGS -fno-strict-aliasing"
-
-    # gcc's builtin memcmp is slower than glibc's
-    # http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43052
-    CXXFLAGS="$CXXFLAGS -fno-builtin-memcmp"
 fi
 
 AC_SUBST([MSVC2013_COMPAT_CFLAGS])