[Mesa-dev] [PATCH] radv: always export gl_SampleMask when the fragment shader uses it

[Bas Nieuwenhuizen]

Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

I'm assuming the real fix is for the shader to not write the sample
mask if we have 1 sample?

On Tue, Feb 12, 2019 at 6:52 PM Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
> For some reasons, this breaks trees rendering in Project Cars.
>
> Fixes: 85010585cde ("radv: only enable gl_SampleMask if MSAA is enabled too")
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109401
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/amd/vulkan/radv_pipeline.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
> index fb6c61cf3f0..a9df2b94b93 100644
> --- a/src/amd/vulkan/radv_pipeline.c
> +++ b/src/amd/vulkan/radv_pipeline.c
> @@ -3183,11 +3183,11 @@ radv_compute_db_shader_control(const struct radv_device *device,
>         bool disable_rbplus = device->physical_device->has_rbplus &&
>                               !device->physical_device->rbplus_allowed;
>
> -       /* Do not enable the gl_SampleMask fragment shader output if MSAA is
> -        * disabled.
> +       /* It shouldn't be needed to export gl_SampleMask when MSAA is disabled
> +        * but this appears to break Project Cars (DXVK). See
> +        * https://bugs.freedesktop.org/show_bug.cgi?id=109401
>          */
> -       bool mask_export_enable = ms->num_samples > 1 &&
> -                                 ps->info.info.ps.writes_sample_mask;
> +       bool mask_export_enable = ps->info.info.ps.writes_sample_mask;
>
>         return  S_02880C_Z_EXPORT_ENABLE(ps->info.info.ps.writes_z) |
>                 S_02880C_STENCIL_TEST_VAL_EXPORT_ENABLE(ps->info.info.ps.writes_stencil) |
> --
> 2.20.1
>
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