[Mesa-dev] [PATCH] llvmpipe: handle shader sample mask output

[Brian Paul]

LGTM.  Reviewed-by: Brian Paul <brianp at vmware.com>

On 10/17/2017 01:58 PM, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
>
> This probably isn't all that useful for GL, but there are apis where
> sample_mask is a valid output even without msaa.
> Just discard the pixel if the sample_mask doesn't include the bit for
> sample 0.
> ---
>   src/gallium/drivers/llvmpipe/lp_state_fs.c | 26 ++++++++++++++++++++++++--
>   1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/drivers/llvmpipe/lp_state_fs.c b/src/gallium/drivers/llvmpipe/lp_state_fs.c
> index 05984b3..9223ce6 100644
> --- a/src/gallium/drivers/llvmpipe/lp_state_fs.c
> +++ b/src/gallium/drivers/llvmpipe/lp_state_fs.c
> @@ -84,6 +84,7 @@
>   #include "gallivm/lp_bld_flow.h"
>   #include "gallivm/lp_bld_debug.h"
>   #include "gallivm/lp_bld_arit.h"
> +#include "gallivm/lp_bld_bitarit.h"
>   #include "gallivm/lp_bld_pack.h"
>   #include "gallivm/lp_bld_format.h"
>   #include "gallivm/lp_bld_quad.h"
> @@ -347,7 +348,8 @@ generate_fs_loop(struct gallivm_state *gallivm,
>         if (!shader->info.base.writes_z && !shader->info.base.writes_stencil) {
>            if (key->alpha.enabled ||
>                key->blend.alpha_to_coverage ||
> -             shader->info.base.uses_kill) {
> +             shader->info.base.uses_kill ||
> +             shader->info.base.writes_samplemask) {
>               /* With alpha test and kill, can do the depth test early
>                * and hopefully eliminate some quads.  But need to do a
>                * special deferred depth write once the final mask value
> @@ -516,6 +518,25 @@ generate_fs_loop(struct gallivm_state *gallivm,
>         }
>      }
>
> +   if (shader->info.base.writes_samplemask) {
> +      int smaski = find_output_by_semantic(&shader->info.base,
> +                                           TGSI_SEMANTIC_SAMPLEMASK,
> +                                           0);
> +      LLVMValueRef smask;
> +      struct lp_build_context smask_bld;
> +      lp_build_context_init(&smask_bld, gallivm, int_type);
> +
> +      assert(smaski >= 0);
> +      smask = LLVMBuildLoad(builder, outputs[smaski][0], "smask");
> +      /*
> +       * Pixel is alive according to the first sample in the mask.
> +       */
> +      smask = LLVMBuildBitCast(builder, smask, smask_bld.vec_type, "");
> +      smask = lp_build_and(&smask_bld, smask, smask_bld.one);
> +      smask = lp_build_cmp(&smask_bld, PIPE_FUNC_NOTEQUAL, smask, smask_bld.zero);
> +      lp_build_mask_update(&mask, smask);
> +   }
> +
>      /* Late Z test */
>      if (depth_mode & LATE_DEPTH_TEST) {
>         int pos0 = find_output_by_semantic(&shader->info.base,
> @@ -2818,7 +2839,8 @@ generate_variant(struct llvmpipe_context *lp,
>            !key->alpha.enabled &&
>            !key->blend.alpha_to_coverage &&
>            !key->depth.enabled &&
> -         !shader->info.base.uses_kill
> +         !shader->info.base.uses_kill &&
> +         !shader->info.base.writes_samplemask
>         ? TRUE : FALSE;
>
>      if ((shader->info.base.num_tokens <= 1) &&
>