Add a CPU flag for the Atom processor.

The Atom has SSSE3 support, which is useful in many cases, but sometimes the
SSSE3 version is slower than the SSE2 equivalent on the Atom, but is generally
faster on other processors supporting SSSE3. This flag allows for selectively
disabling certain SSSE3 functions on the Atom.

libavutil/cpu.c

@@ -58,6 +58,7 @@ int main(void)
            cpu_flags & AV_CPU_FLAG_SSE3     ? "SSE3 "       : "",
            cpu_flags & AV_CPU_FLAG_SSE3SLOW ? "SSE3(slow) " : "",
            cpu_flags & AV_CPU_FLAG_SSSE3    ? "SSSE3 "      : "",
+           cpu_flags & AV_CPU_FLAG_ATOM     ? "Atom "       : "",
            cpu_flags & AV_CPU_FLAG_SSE4     ? "SSE4.1 "     : "",
            cpu_flags & AV_CPU_FLAG_SSE42    ? "SSE4.2 "     : "",
            cpu_flags & AV_CPU_FLAG_AVX      ? "AVX "        : "",

libavutil/cpu.h

@@ -34,6 +34,7 @@
 #define AV_CPU_FLAG_SSE3         0x0040 ///< Prescott SSE3 functions
 #define AV_CPU_FLAG_SSE3SLOW 0x20000000 ///< SSE3 supported, but usually not faster
 #define AV_CPU_FLAG_SSSE3        0x0080 ///< Conroe SSSE3 functions
+#define AV_CPU_FLAG_ATOM     0x10000000 ///< Atom processor, some SSSE3 instructions are slower
 #define AV_CPU_FLAG_SSE4         0x0100 ///< Penryn SSE4.1 functions
 #define AV_CPU_FLAG_SSE42        0x0200 ///< Nehalem SSE4.2 functions
 #define AV_CPU_FLAG_AVX          0x4000 ///< AVX functions: requires OS support even if YMM registers aren't used

libavutil/x86/cpu.c

@@ -135,8 +135,8 @@ int ff_get_cpu_flags_x86(void)
         }
     }
 
-    if (!strncmp(vendor.c, "GenuineIntel", 12) &&
-        family == 6 && (model == 9 || model == 13 || model == 14)) {
+    if (!strncmp(vendor.c, "GenuineIntel", 12)) {
+        if (family == 6 && (model == 9 || model == 13 || model == 14)) {
         /* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and 6/14 (core1 "yonah")
          * theoretically support sse2, but it's usually slower than mmx,
          * so let's just pretend they don't. AV_CPU_FLAG_SSE2 is disabled and
@@ -145,6 +145,14 @@ int ff_get_cpu_flags_x86(void)
          * situation applies for AV_CPU_FLAG_SSE3 and AV_CPU_FLAG_SSE3SLOW. */
         if (rval & AV_CPU_FLAG_SSE2) rval ^= AV_CPU_FLAG_SSE2SLOW|AV_CPU_FLAG_SSE2;
         if (rval & AV_CPU_FLAG_SSE3) rval ^= AV_CPU_FLAG_SSE3SLOW|AV_CPU_FLAG_SSE3;
+        }
+        /* The Atom processor has SSSE3 support, which is useful in many cases,
+         * but sometimes the SSSE3 version is slower than the SSE2 equivalent
+         * on the Atom, but is generally faster on other processors supporting
+         * SSSE3. This flag allows for selectively disabling certain SSSE3
+         * functions on the Atom. */
+        if (family == 6 && model == 28)
+            rval |= AV_CPU_FLAG_ATOM;
     }
 
     return rval;