Expand borders before chroma weightp analysis

Prevents mc from using uninitialized source pixels.

common/frame.c

@@ -542,6 +542,13 @@ void x264_frame_expand_border_lowres( x264_frame_t *frame )
         plane_expand_border( frame->lowres[i], frame->i_stride_lowres, frame->i_width_lowres, frame->i_lines_lowres, PADH, PADV, 1, 1, 0 );
 }
 
+void x264_frame_expand_border_chroma( x264_t *h, x264_frame_t *frame, int plane )
+{
+    int shift = !CHROMA444;
+    plane_expand_border( frame->plane[plane], frame->i_stride[plane], 16*h->mb.i_mb_width, 16*h->mb.i_mb_height>>shift,
+                         PADH, PADV>>shift, 1, 1, shift );
+}
+
 void x264_frame_expand_border_mod16( x264_t *h, x264_frame_t *frame )
 {
     for( int i = 0; i < frame->i_plane; i++ )

common/frame.h

@@ -198,6 +198,7 @@ int           x264_frame_copy_picture( x264_t *h, x264_frame_t *dst, x264_pictur
 void          x264_frame_expand_border( x264_t *h, x264_frame_t *frame, int mb_y, int b_end );
 void          x264_frame_expand_border_filtered( x264_t *h, x264_frame_t *frame, int mb_y, int b_end );
 void          x264_frame_expand_border_lowres( x264_frame_t *frame );
+void          x264_frame_expand_border_chroma( x264_t *h, x264_frame_t *frame, int plane );
 void          x264_frame_expand_border_mod16( x264_t *h, x264_frame_t *frame );
 void          x264_expand_border_mbpair( x264_t *h, int mb_x, int mb_y );
 

encoder/slicetype.c

@@ -115,6 +115,7 @@ static NOINLINE void x264_weight_cost_init_chroma( x264_t *h, x264_frame_t *fenc
 
     if( fenc->lowres_mvs[0][ref0_distance][0][0] != 0x7FFF )
     {
+        x264_frame_expand_border_chroma( h, ref, 1 );
         for( int y = 0, mb_xy = 0, pel_offset_y = 0; y < i_lines; y += 8, pel_offset_y = y*i_stride )
             for( int x = 0, pel_offset_x = 0; x < i_width; x += 8, mb_xy++, pel_offset_x += 8 )
             {
@@ -141,6 +142,7 @@ static NOINLINE pixel *x264_weight_cost_init_chroma444( x264_t *h, x264_frame_t
 
     if( fenc->lowres_mvs[0][ref0_distance][0][0] != 0x7FFF )
     {
+        x264_frame_expand_border_chroma( h, ref, p );
         for( int y = 0, mb_xy = 0, pel_offset_y = 0; y < i_lines; y += 16, pel_offset_y = y*i_stride )
             for( int x = 0, pel_offset_x = 0; x < i_width; x += 16, mb_xy++, pel_offset_x += 16 )
             {