Add 2x2 variance function

Change-Id: I73bcb8ab5727e2d07e34ca35e9e014f3c6f63d56

aom_dsp/aom_dsp_rtcd_defs.pl

@@ -1555,6 +1555,9 @@ specialize qw/aom_get4x4sse_cs neon msa/;
 #
 # Variance / Subpixel Variance / Subpixel Avg Variance
 #
+  add_proto qw/unsigned int/, "aom_variance2x2", "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse";
+  specialize qw/aom_variance2x2/;
+
 foreach (@block_sizes) {
   ($w, $h) = @$_;
   add_proto qw/unsigned int/, "aom_variance${w}x${h}", "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse";

aom_dsp/variance.c

@@ -233,6 +233,7 @@ VARIANCES(8, 8)
 VARIANCES(8, 4)
 VARIANCES(4, 8)
 VARIANCES(4, 4)
+VARIANCES(2, 2)
 
 GET_VAR(16, 16)
 GET_VAR(8, 8)

av1/encoder/encoder.c

@@ -2290,6 +2290,10 @@ AV1_COMP *av1_create_compressor(AV1EncoderConfig *oxcf,
       aom_sub_pixel_variance4x4, aom_sub_pixel_avg_variance4x4, aom_sad4x4x3,
       aom_sad4x4x8, aom_sad4x4x4d)
 
+#if CONFIG_CB4X4
+  BFP(BLOCK_2X2, NULL, NULL, aom_variance2x2, NULL, NULL, NULL, NULL, NULL)
+#endif
+
 #if CONFIG_MOTION_VAR
 #define OBFP(BT, OSDF, OVF, OSVF) \
   cpi->fn_ptr[BT].osdf = OSDF;    \