This patch register spills the mvc_max variable when x264_ultrahardened is defined.
The work in this patch is released under whichever license the x264 project has now or on the future.
Patch is: © (c) 2013 Francisco Blas Izquierdo Riera (klondike) klondike (a t ) gentoo.org
--- common/x86/util.h	2013-09-12 22:45:04.000000000 +0200
+++ common/x86/util.h	2013-11-03 20:35:18.646888328 +0100
@@ -121,11 +121,18 @@
     return amvd;
 }
 
+/*Some hardened systems only have available 4 registers on x86 systems. If that's he case we have to register spill mvc_max*/
+#ifdef x264_ultrahardened
+#define mvc_max_mode "=m"
+#else
+#define mvc_max_mode "+r"
+#endif
+
 #define x264_predictor_clip x264_predictor_clip_mmx2
 static int ALWAYS_INLINE x264_predictor_clip_mmx2( int16_t (*dst)[2], int16_t (*mvc)[2], int i_mvc, int16_t mv_limit[2][2], uint32_t pmv )
 {
     static const uint32_t pd_32 = 0x20;
-    intptr_t tmp = (intptr_t)mv_limit, mvc_max = i_mvc, i = 0;
+    intptr_t tmp = (intptr_t)mv_limit, mvc_max = ((uint32_t *)mvc)+i_mvc, i = 0;
 
     asm(
         "movq       (%2), %%mm5 \n"
@@ -137,7 +145,6 @@
         "punpckldq %%mm3, %%mm3 \n"
         "punpckldq %%mm5, %%mm5 \n"
         "movd         %7, %%mm4 \n"
-        "lea   (%0,%3,4), %3    \n"
         "1:                     \n"
         "movq       (%0), %%mm0 \n"
         "add          $8, %0    \n"
@@ -176,7 +183,7 @@
         "and          $1, %k2   \n"
         "sub          %2, %4    \n" // output += !(mv == pmv || mv == 0)
         "3:                     \n"
-        :"+r"(mvc), "=m"(M64( dst )), "+r"(tmp), "+r"(mvc_max), "+r"(i)
+        :"+r"(mvc), "=m"(M64( dst )), "+r"(tmp), mvc_max_mode(mvc_max), "+r"(i)
         :"r"(dst), "g"(pmv), "m"(pd_32), "m"(M64( mvc ))
     );
     return i;
@@ -188,7 +195,7 @@
 {
     static const uint64_t pw_2 = 0x0002000200020002ULL;
     static const uint32_t pd_32 = 0x20;
-    intptr_t tmp = (intptr_t)mv_limit, mvc_max = i_mvc, i = 0;
+    intptr_t tmp = (intptr_t)mv_limit, mvc_max = ((uint32_t *)mvc)+i_mvc, i = 0;
 
     asm(
         "movq       (%2), %%mm5 \n"
@@ -200,7 +207,6 @@
         "punpckldq %%mm3, %%mm3 \n"
         "punpckldq %%mm5, %%mm5 \n"
         "movd         %8, %%mm4 \n"
-        "lea   (%0,%3,4), %3    \n"
         "1:                     \n"
         "movq       (%0), %%mm0 \n"
         "add          $8, %0    \n"
@@ -243,7 +249,7 @@
         "and          $1, %k2   \n"
         "sub          %2, %4    \n"
         "3:                     \n"
-        :"+r"(mvc), "=m"(M64( dst )), "+r"(tmp), "+r"(mvc_max), "+r"(i)
+        :"+r"(mvc), "=m"(M64( dst )), "+r"(tmp), mvc_max_mode(mvc_max), "+r"(i)
         :"r"(dst), "m"(pw_2), "g"(pmv), "m"(pd_32), "m"(M64( mvc ))
     );
     return i;