anv: handle compiling of mesh shader separately from task shader

With EXT_shader_object, it became possible to compile shaders
independently and then use them together later, so we cannot rely on the
lack of task shader data to decide that no task shader will be used. The
flag VK_SHADER_CREATE_NO_TASK_SHADER_BIT_EXT exists for that purpose,
but it doesn't really make any difference for us. Always assume that if
the mesh shader is reading the task payload, it's going to be used with
one, as otherwise the application is doing it wrong.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13983
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37648>

src/intel/compiler/brw_compile_mesh.cpp

@@ -100,6 +100,8 @@ brw_nir_lower_launch_mesh_workgroups(nir_shader *nir)
                                        NULL);
 }
 
+#define BRW_PER_TASK_DATA_START_DW 8
+
 static void
 brw_nir_lower_tue_outputs(nir_shader *nir, brw_tue_map *map)
 {
@@ -113,7 +115,7 @@ brw_nir_lower_tue_outputs(nir_shader *nir, brw_tue_map *map)
     * alignment.  This allows the TUE Header to always be written as 32 bytes
     * with 32B alignment, the most optimal write performance case."
     */
-   map->per_task_data_start_dw = 8;
+   map->per_task_data_start_dw = BRW_PER_TASK_DATA_START_DW;
 
    /* Lowering to explicit types will start offsets from task_payload_size, so
     * set it to start after the header.
@@ -488,10 +490,13 @@ brw_compile_task(const struct brw_compiler *compiler,
 static void
 brw_nir_lower_tue_inputs(nir_shader *nir, const brw_tue_map *map)
 {
-   if (!map)
-      return;
-
-   nir->info.task_payload_size = map->per_task_data_start_dw * 4;
+   /* See brw_nir_lower_tue_outputs. If a task payload is read by this shader,
+    * task_payload_size will be used to start offsets, and that's always
+    * header + padding.
+    * We can't always use map, as it may not be present if task and mesh
+    * shaders are not compiled together. This is possible with shader objects.
+    */
+   nir->info.task_payload_size = BRW_PER_TASK_DATA_START_DW * 4;
 
    bool progress = false;
 
@@ -502,7 +507,7 @@ brw_nir_lower_tue_inputs(nir_shader *nir, const brw_tue_map *map)
       /* The types for Task Output and Mesh Input should match, so their sizes
        * should also match.
        */
-      assert(map->size_dw == ALIGN(DIV_ROUND_UP(nir->info.task_payload_size, 4), 8));
+      assert(!map || map->size_dw == ALIGN(DIV_ROUND_UP(nir->info.task_payload_size, 4), 8));
    } else {
       /* Mesh doesn't read any input, to make it clearer set the
        * task_payload_size to zero instead of keeping an incomplete size that