[Mesa-dev] [PATCH 1/2] blorp: Don't try to use R32_UNORM for R24_UNORM_X8_TYPELESS rendering.

[Jason Ekstrand]

On August 10, 2018 03:19:18 Kenneth Graunke <kenneth at whitecape.org> wrote:

> The hardware doesn't support rendering to R24_UNORM_X8_TYPELESS, so
> Jason decided to fake it with a bit of shader math and R32_UNORM RTs.
>
> The only problem is that R32_UNORM isn't renderable either...so we've
> just traded one bad format for another.
>
> This patch makes us use R32_UINT instead.
> ---
> src/intel/blorp/blorp_blit.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/src/intel/blorp/blorp_blit.c b/src/intel/blorp/blorp_blit.c
> index c85ec8543a9..7b49f9afa35 100644
> --- a/src/intel/blorp/blorp_blit.c
> +++ b/src/intel/blorp/blorp_blit.c
> @@ -984,14 +984,15 @@ convert_color(struct nir_builder *b, nir_ssa_def *color,
>    nir_ssa_def *value;
>
>    if (key->dst_format == ISL_FORMAT_R24_UNORM_X8_TYPELESS) {
> -      /* The destination image is bound as R32_UNORM but the data needs to be
> +      /* The destination image is bound as R32_UINT but the data needs to be
>        * in R24_UNORM_X8_TYPELESS.  The bottom 24 are the actual data and the
>        * top 8 need to be zero.  We can accomplish this by simply multiplying
>        * by a factor to scale things down.
>        */
> -      float factor = (float)((1 << 24) - 1) / (float)UINT32_MAX;
> -      value = nir_fmul(b, nir_fsat(b, nir_channel(b, color, 0)),
> -                          nir_imm_float(b, factor));
> +      unsigned factor = (1 << 24) - 1;
> +      value = nir_fsat(b, nir_channel(b, color, 0));
> +      value = nir_fmul(b, value, nir_imm_float(b, factor));
> +      value = nir_iand(b, nir_f2i32(b, value), nir_imm_int(b, factor));

Do we really need the and?

>    } else if (key->dst_format == ISL_FORMAT_L8_UNORM_SRGB) {
>       value = nir_format_linear_to_srgb(b, nir_channel(b, color, 0));
>    } else if (key->dst_format == ISL_FORMAT_R8G8B8_UNORM_SRGB) {
> @@ -1976,7 +1977,7 @@ try_blorp_blit(struct blorp_batch *batch,
>          isl_format_rgbx_to_rgba(params->dst.view.format);
>    } else if (params->dst.view.format == ISL_FORMAT_R24_UNORM_X8_TYPELESS) {
>       wm_prog_key->dst_format = params->dst.view.format;
> -      params->dst.view.format = ISL_FORMAT_R32_UNORM;
> +      params->dst.view.format = ISL_FORMAT_R32_UINT;
>    } else if (params->dst.view.format == ISL_FORMAT_A4B4G4R4_UNORM) {
>       params->dst.view.swizzle =
>          isl_swizzle_compose(params->dst.view.swizzle,
> --
> 2.18.0
>
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