[Mesa-dev] [PATCH 07/15] i965/vec4: Simplify reswizzle() using the swizzle utils.

[Matt Turner]

On Fri, Mar 20, 2015 at 7:11 AM, Francisco Jerez <currojerez at riseup.net> wrote:
> ---
>  src/mesa/drivers/dri/i965/brw_vec4.cpp | 40 ++++++++++------------------------
>  1 file changed, 11 insertions(+), 29 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index 60f85f8..3e5f6c4 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -998,43 +998,25 @@ vec4_instruction::can_reswizzle(int dst_writemask,
>  void
>  vec4_instruction::reswizzle(int dst_writemask, int swizzle)
>  {
> -   int new_writemask = 0;
> -   int new_swizzle[4] = { 0 };
> -
> -   /* Dot product instructions write a single result into all channels. */
> +   /* Destination write mask doesn't correspond to source swizzle for the dot
> +    * product and pack_bytes instructions.
> +    */
>     if (opcode != BRW_OPCODE_DP4 && opcode != BRW_OPCODE_DPH &&
> -       opcode != BRW_OPCODE_DP3 && opcode != BRW_OPCODE_DP2) {
> +       opcode != BRW_OPCODE_DP3 && opcode != BRW_OPCODE_DP2 &&
> +       opcode != VEC4_OPCODE_PACK_BYTES) {
>        for (int i = 0; i < 3; i++) {
>           if (src[i].file == BAD_FILE || src[i].file == IMM)
>              continue;
>
> -         /* Destination write mask doesn't correspond to source swizzle for the
> -          * pack_bytes instruction.
> -          */
> -         if (opcode == VEC4_OPCODE_PACK_BYTES)
> -            continue;
> -
> -         for (int c = 0; c < 4; c++) {
> -            new_swizzle[c] = BRW_GET_SWZ(src[i].swizzle, BRW_GET_SWZ(swizzle, c));
> -         }
> -
> -         src[i].swizzle = BRW_SWIZZLE4(new_swizzle[0], new_swizzle[1],
> -                                       new_swizzle[2], new_swizzle[3]);
> +         src[i].swizzle = brw_compose_swizzle(swizzle, src[i].swizzle);
>        }
>     }
>
> -   for (int c = 0; c < 4; c++) {
> -      int bit = 1 << BRW_GET_SWZ(swizzle, c);
> -      /* Skip components of the swizzle not used by the dst. */
> -      if (!(dst_writemask & (1 << c)))
> -         continue;
> -      /* If we were populating this component, then populate the
> -       * corresponding channel of the new dst.
> -       */
> -      if (dst.writemask & bit)
> -         new_writemask |= (1 << c);
> -   }
> -   dst.writemask = new_writemask;
> +   /* Apply the specified swizzle and writemask to the original mask of
> +    * written components.
> +    */
> +   dst.writemask = dst_writemask &
> +      brw_apply_swizzle_to_mask(swizzle, dst.writemask);

I'd indent this to line up vertically with dst_writemask.