[Mesa-dev] [PATCH 5/6] gallivm: generalize the compressed format soa fetch a bit

[Jose Fonseca]

On 12/12/16 00:12, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
>
> This can now handle rgtc (unorm) too - this path no longer handles plain
> formats, but that's unnecessary they now all have their proper SoA unpack
> (this will still be dog-slow though due to the actual fetch being per-pixel
> util fallbacks).
> ---
>  src/gallium/auxiliary/gallivm/lp_bld_format_soa.c | 86 +++++++++++++----------
>  1 file changed, 49 insertions(+), 37 deletions(-)
>
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_format_soa.c b/src/gallium/auxiliary/gallivm/lp_bld_format_soa.c
> index 9550f26..68cbb10 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_format_soa.c
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_format_soa.c
> @@ -733,64 +733,69 @@ lp_build_fetch_rgba_soa(struct gallivm_state *gallivm,
>
>     /*
>      * Try calling lp_build_fetch_rgba_aos for all pixels.
> +    * Should only really hit subsampled, compressed
> +    * (for s3tc srgb too, for rgtc the unorm ones only) by now.
> +    * (This is invalid for plain 8unorm formats because we're lazy with
> +    * the swizzle since some results would arrive swizzled, some not.)
>      */
>
> -   if (util_format_fits_8unorm(format_desc) &&
> +   if ((format_desc->layout != UTIL_FORMAT_LAYOUT_PLAIN) &&
> +       (util_format_fits_8unorm(format_desc) ||
> +        format_desc->layout == UTIL_FORMAT_LAYOUT_S3TC) &&
>         type.floating && type.width == 32 &&
>         (type.length == 1 || (type.length % 4 == 0))) {
>        struct lp_type tmp_type;
> -      LLVMValueRef tmp;
> +      struct lp_build_context bld;
> +      LLVMValueRef packed, rgba[4];
> +      const struct util_format_description *flinear_desc;
> +      const struct util_format_description *frgba8_desc;
> +      unsigned chan;
>
> +      lp_build_context_init(&bld, gallivm, type);
> +
> +      /*
> +       * Make sure the conversion in aos really only does convert to rgba8
> +       * and not anything more (so use linear format, adjust type).
> +       */
> +      flinear_desc = util_format_description(util_format_linear(format));
>        memset(&tmp_type, 0, sizeof tmp_type);
>        tmp_type.width = 8;
>        tmp_type.length = type.length * 4;
>        tmp_type.norm = TRUE;
>
> -      tmp = lp_build_fetch_rgba_aos(gallivm, format_desc, tmp_type,
> -                                    aligned, base_ptr, offset, i, j, cache);
> +      packed = lp_build_fetch_rgba_aos(gallivm, flinear_desc, tmp_type,
> +                                       aligned, base_ptr, offset, i, j, cache);
> +      packed = LLVMBuildBitCast(builder, packed, bld.int_vec_type, "");
>
> -      lp_build_rgba8_to_fi32_soa(gallivm,
> -                                type,
> -                                tmp,
> -                                rgba_out);
> -
> -      return;
> -   }
> -
> -   if (format_desc->layout == UTIL_FORMAT_LAYOUT_S3TC &&
> -       /* non-srgb case is already handled above */
> -       format_desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB &&
> -       type.floating && type.width == 32 &&
> -       (type.length == 1 || (type.length % 4 == 0)) &&
> -       cache) {
> -      const struct util_format_description *format_decompressed;
> -      const struct util_format_description *flinear_desc;
> -      LLVMValueRef packed;
> -      flinear_desc = util_format_description(util_format_linear(format_desc->format));
> -      /* This probably only works with aligned data */
> -      packed = lp_build_fetch_cached_texels(gallivm,
> -                                            flinear_desc,
> -                                            type.length,
> -                                            base_ptr,
> -                                            offset,
> -                                            i, j,
> -                                            cache);
> -      packed = LLVMBuildBitCast(builder, packed,
> -                                lp_build_int_vec_type(gallivm, type), "");
>        /*
> -       * The values are now packed so they match ordinary srgb RGBA8 format,
> +       * The values are now packed so they match ordinary (srgb) RGBA8 format,
>         * hence need to use matching format for unpack.
>         */
> -      format_decompressed = util_format_description(PIPE_FORMAT_R8G8B8A8_SRGB);
> -
> +      frgba8_desc = util_format_description(PIPE_FORMAT_R8G8B8A8_UNORM);
> +      if (format_desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) {
> +         assert(format_desc->layout == UTIL_FORMAT_LAYOUT_S3TC);
> +         frgba8_desc = util_format_description(PIPE_FORMAT_R8G8B8A8_SRGB);
> +      }
>        lp_build_unpack_rgba_soa(gallivm,
> -                               format_decompressed,
> +                               frgba8_desc,
>                                 type,
> -                               packed, rgba_out);
> +                               packed, rgba);
>
> +      /*
> +       * We converted 4 channels. Make sure llvm can drop unneeded ones
> +       * (luckily the rgba order is fixed, only la needs special case).

"la" is confusing.  It's better to use upper-case, like LA, RGTC,

> +       */
> +      for (chan = 0; chan < 4; chan++) {
> +         enum pipe_swizzle swizzle = format_desc->swizzle[chan];
> +         if (chan == 3 && util_format_is_luminance_alpha(format)) {
> +            swizzle = PIPE_SWIZZLE_W;
> +         }
> +         rgba_out[chan] = lp_build_swizzle_soa_channel(&bld, rgba, swizzle);
> +      }
>        return;
>     }
>
> +
>     /*
>      * Fallback to calling lp_build_fetch_rgba_aos for each pixel.
>      *
> @@ -798,6 +803,13 @@ lp_build_fetch_rgba_soa(struct gallivm_state *gallivm,
>      * miss some opportunities to do vectorization, but this is
>      * convenient for formats or scenarios for which there was no
>      * opportunity or incentive to optimize.
> +    *
> +    * We do NOT want to end up here, this typically is quite terrible,
> +    * in particular if the formats have less than 4 channels.
> +    *
> +    * Right now, this should only be hit for:
> +    * - rgtc snorm formats
> +    *   (those miss fast fetch functions hence they are terrible anyway)
>      */
>
>     {
>


Otherwise looks good AFAICT.

Reviewed-by: Jose Fonseca <jfonseca at vmware.com>