swscale/ops: mark all unused components as GARBAGE

This only affects the print-out of the SWS_OP_WRITE at the end of every op,
list, because the ops list print-out was otherwise already checking the unused
mask.

 rgb24 -> bgr24:
   [ u8 XXXX -> +++X] SWS_OP_READ         : 3 elem(s) packed >> 0
     min: {0 0 0 _}, max: {255 255 255 _}
   [ u8 ...X -> +++X] SWS_OP_SWIZZLE      : 2103
     min: {0 0 0 _}, max: {255 255 255 _}
-  [ u8 ...X -> +++X] SWS_OP_WRITE        : 3 elem(s) packed >> 0
+  [ u8 ...X -> XXXX] SWS_OP_WRITE        : 3 elem(s) packed >> 0
     min: {0 0 0 _}, max: {255 255 255 _}
     (X = unused, z = byteswapped, + = exact, 0 = zero)

Signed-off-by: Niklas Haas <git@haasn.dev>

libswscale/ops.c

@@ -472,6 +472,11 @@ void ff_sws_op_list_update_comps(SwsOpList *ops)
         SwsOp *op = &ops->ops[n];
         bool need_in[4] = { false, false, false, false };
 
+        for (int i = 0; i < 4; i++) {
+            if (!need_out[i])
+                op->comps.flags[i] = SWS_COMP_GARBAGE;
+        }
+
         switch (op->op) {
         case SWS_OP_READ:
         case SWS_OP_WRITE:

tests/ref/fate/sws-ops-list

@@ -1 +1 @@
-e5a6788fa43852d75544e7fb6ae7744d
+da5cdcd09fffb274b454a64f1d95b073