draw: add mesh shader infrastructure

This adds draw mesh shader infrastructure, as mesh shaders have
to be able to feed into the post vs stages like clipping, so
we have to wire informational things up.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23066>

src/gallium/auxiliary/draw/draw_context.c

@@ -44,6 +44,7 @@
 #include "draw_vs.h"
 #include "draw_gs.h"
 #include "draw_tess.h"
+#include "draw_mesh.h"
 
 #ifdef DRAW_LLVM_AVAILABLE
 #include "gallivm/lp_bld_init.h"
@@ -626,7 +627,9 @@ draw_remove_extra_vertex_attribs(struct draw_context *draw)
 struct tgsi_shader_info *
 draw_get_shader_info(const struct draw_context *draw)
 {
-   if (draw->gs.geometry_shader) {
+   if (draw->ms.mesh_shader) {
+      return &draw->ms.mesh_shader->info;
+   } else if (draw->gs.geometry_shader) {
       return &draw->gs.geometry_shader->info;
    } else if (draw->tes.tess_eval_shader) {
       return &draw->tes.tess_eval_shader->info;
@@ -921,6 +924,8 @@ void draw_do_flush(struct draw_context *draw, unsigned flags)
 uint
 draw_current_shader_outputs(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.num_ms_outputs;
    if (draw->gs.geometry_shader)
       return draw->gs.num_gs_outputs;
    if (draw->tes.tess_eval_shader)
@@ -936,6 +941,8 @@ draw_current_shader_outputs(const struct draw_context *draw)
 uint
 draw_current_shader_position_output(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.position_output;
    if (draw->gs.geometry_shader)
       return draw->gs.position_output;
    if (draw->tes.tess_eval_shader)
@@ -951,6 +958,8 @@ draw_current_shader_position_output(const struct draw_context *draw)
 uint
 draw_current_shader_viewport_index_output(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.mesh_shader->viewport_index_output;
    if (draw->gs.geometry_shader)
       return draw->gs.geometry_shader->viewport_index_output;
    else if (draw->tes.tess_eval_shader)
@@ -966,6 +975,8 @@ draw_current_shader_viewport_index_output(const struct draw_context *draw)
 boolean
 draw_current_shader_uses_viewport_index(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.mesh_shader->info.writes_viewport_index;
    if (draw->gs.geometry_shader)
       return draw->gs.geometry_shader->info.writes_viewport_index;
    else if (draw->tes.tess_eval_shader)
@@ -983,6 +994,8 @@ draw_current_shader_uses_viewport_index(const struct draw_context *draw)
 uint
 draw_current_shader_clipvertex_output(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.clipvertex_output;
    if (draw->gs.geometry_shader)
       return draw->gs.clipvertex_output;
    if (draw->tes.tess_eval_shader)
@@ -995,6 +1008,8 @@ uint
 draw_current_shader_ccdistance_output(const struct draw_context *draw, int index)
 {
    assert(index < PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT);
+   if (draw->ms.mesh_shader)
+      return draw->ms.mesh_shader->ccdistance_output[index];
    if (draw->gs.geometry_shader)
       return draw->gs.geometry_shader->ccdistance_output[index];
    if (draw->tes.tess_eval_shader)
@@ -1006,6 +1021,8 @@ draw_current_shader_ccdistance_output(const struct draw_context *draw, int index
 uint
 draw_current_shader_num_written_clipdistances(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.mesh_shader->info.num_written_clipdistance;
    if (draw->gs.geometry_shader)
       return draw->gs.geometry_shader->info.num_written_clipdistance;
    if (draw->tes.tess_eval_shader)
@@ -1016,6 +1033,8 @@ draw_current_shader_num_written_clipdistances(const struct draw_context *draw)
 uint
 draw_current_shader_num_written_culldistances(const struct draw_context *draw)
 {
+   if (draw->ms.mesh_shader)
+      return draw->ms.mesh_shader->info.num_written_culldistance;
    if (draw->gs.geometry_shader)
       return draw->gs.geometry_shader->info.num_written_culldistance;
    if (draw->tes.tess_eval_shader)

src/gallium/auxiliary/draw/draw_context.h

@@ -48,6 +48,7 @@ struct draw_vertex_shader;
 struct draw_geometry_shader;
 struct draw_tess_ctrl_shader;
 struct draw_tess_eval_shader;
+struct draw_mesh_shader;
 struct draw_fragment_shader;
 struct tgsi_sampler;
 struct tgsi_image;
@@ -281,6 +282,17 @@ void draw_set_tess_state(struct draw_context *draw,
                          const float default_outer_level[4],
                          const float default_inner_level[2]);
 
+/*
+ * Mesh shader functions
+ */
+struct draw_mesh_shader *
+draw_create_mesh_shader(struct draw_context *draw,
+                        const struct pipe_shader_state *shader);
+void draw_bind_mesh_shader(struct draw_context *draw,
+                           struct draw_mesh_shader *dvs);
+void draw_delete_mesh_shader(struct draw_context *draw,
+                             struct draw_mesh_shader *dvs);
+
 /*
  * Vertex data functions
  */

src/gallium/auxiliary/draw/draw_mesh.c

@@ -0,0 +1,101 @@
+/**************************************************************************
+ *
+ * Copyright 2023 Red Hat.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#include "draw_mesh.h"
+#include "draw_context.h"
+
+#include "tgsi/tgsi_scan.h"
+#include "nir/nir_to_tgsi_info.h"
+#include "pipe/p_shader_tokens.h"
+
+struct draw_mesh_shader *
+draw_create_mesh_shader(struct draw_context *draw,
+                        const struct pipe_shader_state *state)
+{
+   struct draw_mesh_shader *ms;
+
+   ms = CALLOC_STRUCT(draw_mesh_shader);
+
+   if (!ms)
+      return NULL;
+
+   ms->draw = draw;
+
+   nir_tgsi_scan_shader(state->ir.nir, &ms->info, true);
+
+   nir_shader *nir = state->ir.nir;
+
+   ms->output_primitive = nir->info.mesh.primitive_type;
+
+   ms->position_output = -1;
+   bool found_clipvertex = false;
+   for (unsigned i = 0; i < ms->info.num_outputs; i++) {
+      if (ms->info.output_semantic_name[i] == TGSI_SEMANTIC_POSITION &&
+          ms->info.output_semantic_index[i] == 0)
+         ms->position_output = i;
+      if (ms->info.output_semantic_name[i] == TGSI_SEMANTIC_VIEWPORT_INDEX)
+         ms->viewport_index_output = i;
+      if (ms->info.output_semantic_name[i] == TGSI_SEMANTIC_CLIPVERTEX &&
+          ms->info.output_semantic_index[i] == 0) {
+         found_clipvertex = true;
+         ms->clipvertex_output = i;
+      }
+      if (ms->info.output_semantic_name[i] == TGSI_SEMANTIC_CLIPDIST) {
+         assert(ms->info.output_semantic_index[i] <
+                      PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT);
+         ms->ccdistance_output[ms->info.output_semantic_index[i]] = i;
+      }
+   }
+   if (!found_clipvertex)
+      ms->clipvertex_output = ms->position_output;
+   return ms;
+}
+
+void
+draw_bind_mesh_shader(struct draw_context *draw,
+                      struct draw_mesh_shader *dms)
+{
+   draw_do_flush(draw, DRAW_FLUSH_STATE_CHANGE);
+
+   if (dms) {
+      draw->ms.mesh_shader = dms;
+      draw->ms.num_ms_outputs = dms->info.num_outputs;
+      draw->ms.position_output = dms->position_output;
+      draw->ms.clipvertex_output = dms->clipvertex_output;
+   } else {
+      draw->ms.mesh_shader = NULL;
+      draw->ms.num_ms_outputs = 0;
+   }
+}
+
+void
+draw_delete_mesh_shader(struct draw_context *draw,
+                        struct draw_mesh_shader *dms)
+{
+   if (!dms)
+      return;
+
+   FREE(dms);
+}

src/gallium/auxiliary/draw/draw_mesh.h

@@ -0,0 +1,48 @@
+/**************************************************************************
+ *
+ * Copyright 2023 Red Hat.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#ifndef DRAW_MESH_H
+#define DRAW_MESH_H
+
+#include "draw_context.h"
+#include "draw_private.h"
+#include "tgsi/tgsi_exec.h"
+#include "tgsi/tgsi_scan.h"
+
+struct draw_context;
+
+struct draw_mesh_shader {
+   struct draw_context *draw;
+
+   struct tgsi_shader_info info;
+
+   unsigned position_output;
+   unsigned viewport_index_output;
+   unsigned clipvertex_output;
+   unsigned ccdistance_output[PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT];
+   unsigned output_primitive;
+};
+
+#endif

src/gallium/auxiliary/draw/draw_private.h

@@ -356,6 +356,13 @@ struct draw_context
       struct draw_fragment_shader *fragment_shader;
    } fs;
 
+   struct {
+      struct draw_mesh_shader *mesh_shader;
+      uint num_ms_outputs;  /**< convenience, from geometry_shader */
+      uint position_output;
+      uint clipvertex_output;
+   } ms;
+
    /** Stream output (vertex feedback) state */
    struct {
       struct draw_so_target *targets[PIPE_MAX_SO_BUFFERS];

src/gallium/auxiliary/draw/draw_pt_so_emit.c

@@ -61,6 +61,8 @@ draw_so_info(const struct draw_context *draw)
 {
    const struct pipe_stream_output_info *state = NULL;
 
+   if (draw->ms.mesh_shader)
+      return state;
    if (draw->gs.geometry_shader) {
       state = &draw->gs.geometry_shader->state.stream_output;
    } else if (draw->tes.tess_eval_shader) {

src/gallium/auxiliary/meson.build

@@ -34,6 +34,8 @@ files_libgallium = files(
   'draw/draw_gs.c',
   'draw/draw_gs.h',
   'draw/draw_gs_tmp.h',
+  'draw/draw_mesh.c',
+  'draw/draw_mesh.h',
   'draw/draw_pipe_aaline.c',
   'draw/draw_pipe_aapoint.c',
   'draw/draw_pipe.c',