Simplify conditional code in nested loops of encode_b functions

This patch simplifies the conditional code in nested 'for' loops
in encode_superblock() and av1_update_state().

Speed data for RT preset.
     Instruction Count
cpu    Reduction(%)
 7       0.214
 8       0.242
 9       0.458
10       0.502

Change-Id: I0fb4edac721a687fa90c71016faedddb7ab65e21

av1/encoder/encodeframe_utils.c

diff --git a/av1/encoder/encodeframe_utils.c b/av1/encoder/encodeframe_utils.c
index 4271338..c5c8686 100644
--- a/av1/encoder/encodeframe_utils.c
+++ b/av1/encoder/encodeframe_utils.c
@@ -347,13 +347,13 @@
   for (i = 0; i < 2; ++i) pd[i].color_index_map = ctx->color_index_map[i];
   // Restore the coding context of the MB to that that was in place
   // when the mode was picked for it
-  for (y = 0; y < mi_height; y++) {
-    for (x_idx = 0; x_idx < mi_width; x_idx++) {
-      if ((xd->mb_to_right_edge >> (3 + MI_SIZE_LOG2)) + mi_width > x_idx &&
-          (xd->mb_to_bottom_edge >> (3 + MI_SIZE_LOG2)) + mi_height > y) {
-        xd->mi[x_idx + y * mis] = mi_addr;
-      }
-    }
+
+  const int cols =
+      AOMMIN((xd->mb_to_right_edge >> (3 + MI_SIZE_LOG2)) + mi_width, mi_width);
+  const int rows = AOMMIN(
+      (xd->mb_to_bottom_edge >> (3 + MI_SIZE_LOG2)) + mi_height, mi_height);
+  for (y = 0; y < rows; y++) {
+    for (x_idx = 0; x_idx < cols; x_idx++) xd->mi[x_idx + y * mis] = mi_addr;
   }
 
   if (cpi->oxcf.q_cfg.aq_mode)

av1/encoder/partition_search.c

diff --git a/av1/encoder/partition_search.c b/av1/encoder/partition_search.c
index 45458c9..75747a8 100644
--- a/av1/encoder/partition_search.c
+++ b/av1/encoder/partition_search.c
@@ -530,11 +530,11 @@
         intra_tx_size = mbmi->tx_size;
       }
 
-      for (j = 0; j < mi_height; j++)
-        for (i = 0; i < mi_width; i++)
-          if (mi_col + i < cm->mi_params.mi_cols &&
-              mi_row + j < cm->mi_params.mi_rows)
-            mi_4x4[mis * j + i]->tx_size = intra_tx_size;
+      const int cols = AOMMIN(cm->mi_params.mi_cols - mi_col, mi_width);
+      const int rows = AOMMIN(cm->mi_params.mi_rows - mi_row, mi_height);
+      for (j = 0; j < rows; j++) {
+        for (i = 0; i < cols; i++) mi_4x4[mis * j + i]->tx_size = intra_tx_size;
+      }
 
       if (intra_tx_size != max_txsize_rect_lookup[bsize])
         ++x->txfm_search_info.txb_split_count;