shithub: libvpx

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Cache optimizations in optimize_b().

Move best index into the token state. Shrink it down to one byte. This
is more cache friendly (access are group together) and uses less total
memory.

Results in 4% fewer cycles in optimize_b().

Change-Id: I75db484fb3dc82f59928d54b659d79c80ee40452

--- a/vp9/encoder/vp9_encodemb.c

+++ b/vp9/encoder/vp9_encodemb.c

@@ -57,6 +57,7 @@

   int16_t       token;

   tran_low_t    qc;

   tran_low_t    dqc;

+  uint8_t       best_index;

 } vp9_token_state;

 static const int plane_rd_mult[REF_TYPES][PLANE_TYPES] ={ {10, 6}, {8, 5}, };

@@ -87,7 +88,6 @@

   struct macroblockd_plane *const pd = &xd->plane[plane];

   const int ref = is_inter_block(xd->mi[0]);

   vp9_token_state tokens[1025][2];

-  unsigned best_index[1025][2];

   uint8_t token_cache[1024];

   const tran_low_t *const coeff = BLOCK_OFFSET(mb->plane[plane].coeff, block);

   tran_low_t *const qcoeff = BLOCK_OFFSET(p->qcoeff, block);

@@ -172,7 +172,7 @@

       tokens[i][0].token = t0;

       tokens[i][0].qc = x;

       tokens[i][0].dqc = dqcoeff[rc];

-      best_index[i][0] = best;

+      tokens[i][0].best_index = best;

       /* Evaluate the second possibility for this state. */

       rate0 = tokens[next][0].rate;

@@ -190,7 +190,6 @@

         x -= 2 * sz + 1;

       } else {

         tokens[i][1] = tokens[i][0];

-        best_index[i][1] = best_index[i][0];

         next = i;

         continue;

       }

@@ -261,7 +260,7 @@

         tokens[i][1].dqc = 0;

       }

-      best_index[i][1] = best;

+      tokens[i][1].best_index = best;

       /* Finally, make this the new head of the trellis. */

       next = i;

     } else {

@@ -283,7 +282,7 @@

             mb->token_costs[tx_size][type][ref][band][1][pt][t1];

         tokens[next][1].token = ZERO_TOKEN;

       }

-      best_index[i][0] = best_index[i][1] = 0;

+      tokens[i][0].best_index = tokens[i][1].best_index = 0;

       /* Don't update next, because we didn't add a new node. */

     }

   }

@@ -309,7 +308,7 @@

     qcoeff[rc] = x;

     dqcoeff[rc] = tokens[i][best].dqc;

     next = tokens[i][best].next;

-    best = best_index[i][best];

+    best = tokens[i][best].best_index;

   }

   final_eob++;