Reduce call of av1_get_interp_filter_params_with_block_size

Calls of av1_get_interp_filter_params_with_block_size to get filter
parameters for x and y direction are required only when convolve
is applied on that direction.

This change makes decoder a little bit faster ~0.3%.

Change-Id: I153e5e3792da42b826a677761005a41e90c99cc2

av1/common/convolve.c

diff --git a/av1/common/convolve.c b/av1/common/convolve.c
index ed962c7..0942131 100644
--- a/av1/common/convolve.c
+++ b/av1/common/convolve.c
@@ -520,12 +520,22 @@
   (void)y_step_q4;
   (void)dst;
   (void)dst_stride;
-  InterpFilter filter_x = av1_extract_interp_filter(interp_filters, 1);
-  InterpFilter filter_y = av1_extract_interp_filter(interp_filters, 0);
+  InterpFilter filter_x;
+  InterpFilter filter_y;
+  const int need_filter_params_x = (subpel_x_q4 != 0) | scaled;
+  const int need_filter_params_y = (subpel_y_q4 != 0) | scaled;
+  if (need_filter_params_x)
+    filter_x = av1_extract_interp_filter(interp_filters, 1);
+  if (need_filter_params_y)
+    filter_y = av1_extract_interp_filter(interp_filters, 0);
   const InterpFilterParams *filter_params_x =
-      av1_get_interp_filter_params_with_block_size(filter_x, w);
+      need_filter_params_x
+          ? av1_get_interp_filter_params_with_block_size(filter_x, w)
+          : NULL;
   const InterpFilterParams *filter_params_y =
-      av1_get_interp_filter_params_with_block_size(filter_y, h);
+      need_filter_params_y
+          ? av1_get_interp_filter_params_with_block_size(filter_y, h)
+          : NULL;
 
   if (scaled)
     convolve_2d_scale_wrapper(src, src_stride, dst, dst_stride, w, h,
@@ -976,12 +986,22 @@
   (void)dst_stride;
 
   const uint16_t *src = CONVERT_TO_SHORTPTR(src8);
-  InterpFilter filter_x = av1_extract_interp_filter(interp_filters, 1);
-  InterpFilter filter_y = av1_extract_interp_filter(interp_filters, 0);
+  InterpFilter filter_x;
+  InterpFilter filter_y;
+  const int need_filter_params_x = (subpel_x_q4 != 0) | scaled;
+  const int need_filter_params_y = (subpel_y_q4 != 0) | scaled;
+  if (need_filter_params_x)
+    filter_x = av1_extract_interp_filter(interp_filters, 1);
+  if (need_filter_params_y)
+    filter_y = av1_extract_interp_filter(interp_filters, 0);
   const InterpFilterParams *filter_params_x =
-      av1_get_interp_filter_params_with_block_size(filter_x, w);
+      need_filter_params_x
+          ? av1_get_interp_filter_params_with_block_size(filter_x, w)
+          : NULL;
   const InterpFilterParams *filter_params_y =
-      av1_get_interp_filter_params_with_block_size(filter_y, h);
+      need_filter_params_y
+          ? av1_get_interp_filter_params_with_block_size(filter_y, h)
+          : NULL;
 
   if (scaled) {
     uint16_t *dst = CONVERT_TO_SHORTPTR(dst8);