VP8: idct_mb optimizations

Currently uses AV_RL32 instead of AV_RL32A, as the latter doesn't exist yet.
(cherry picked from commit 62457f90)

libavcodec/vp8.c

@@ -1421,17 +1421,17 @@ static av_always_inline void idct_mb(VP8Context *s, uint8_t *dst[3], VP8Macroblo
     if (mb->mode != MODE_I4x4) {
         uint8_t *y_dst = dst[0];
         for (y = 0; y < 4; y++) {
-            uint32_t nnz4 = AV_RN32A(s->non_zero_count_cache[y]);
+            uint32_t nnz4 = AV_RL32(s->non_zero_count_cache[y]);
             if (nnz4) {
                 if (nnz4&~0x01010101) {
                     for (x = 0; x < 4; x++) {
-                        int nnz = s->non_zero_count_cache[y][x];
-                        if (nnz) {
-                            if (nnz == 1)
-                                s->vp8dsp.vp8_idct_dc_add(y_dst+4*x, s->block[y][x], s->linesize);
-                            else
-                                s->vp8dsp.vp8_idct_add(y_dst+4*x, s->block[y][x], s->linesize);
-                        }
+                        if ((uint8_t)nnz4 == 1)
+                            s->vp8dsp.vp8_idct_dc_add(y_dst+4*x, s->block[y][x], s->linesize);
+                        else if((uint8_t)nnz4 > 1)
+                            s->vp8dsp.vp8_idct_add(y_dst+4*x, s->block[y][x], s->linesize);
+                        nnz4 >>= 8;
+                        if (!nnz4)
+                            break;
                     }
                 } else {
                     s->vp8dsp.vp8_idct_dc_add4y(y_dst, s->block[y], s->linesize);
@@ -1442,19 +1442,19 @@ static av_always_inline void idct_mb(VP8Context *s, uint8_t *dst[3], VP8Macroblo
     }
 
     for (ch = 0; ch < 2; ch++) {
-        uint32_t nnz4 = AV_RN32A(s->non_zero_count_cache[4+ch]);
+        uint32_t nnz4 = AV_RL32(s->non_zero_count_cache[4+ch]);
         if (nnz4) {
             uint8_t *ch_dst = dst[1+ch];
             if (nnz4&~0x01010101) {
                 for (y = 0; y < 2; y++) {
                     for (x = 0; x < 2; x++) {
-                        int nnz = s->non_zero_count_cache[4+ch][(y<<1)+x];
-                        if (nnz) {
-                            if (nnz == 1)
-                                s->vp8dsp.vp8_idct_dc_add(ch_dst+4*x, s->block[4+ch][(y<<1)+x], s->uvlinesize);
-                            else
-                                s->vp8dsp.vp8_idct_add(ch_dst+4*x, s->block[4+ch][(y<<1)+x], s->uvlinesize);
-                        }
+                        if ((uint8_t)nnz4 == 1)
+                            s->vp8dsp.vp8_idct_dc_add(ch_dst+4*x, s->block[4+ch][(y<<1)+x], s->uvlinesize);
+                        else if((uint8_t)nnz4 > 1)
+                            s->vp8dsp.vp8_idct_add(ch_dst+4*x, s->block[4+ch][(y<<1)+x], s->uvlinesize);
+                        nnz4 >>= 8;
+                        if (!nnz4)
+                            break;
                     }
                     ch_dst += 4*s->uvlinesize;
                 }