glsl: plumb num_views down to shader_info::view_mask

this is needed for drivers to more effectively compile multiview-enabled
shaders

Reviewed-by: Timothy Arceri <tarceri@itqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33016>

src/compiler/glsl/ast_type.cpp

@@ -524,10 +524,10 @@ ast_type_qualifier::merge_qualifier(YYLTYPE *loc,
       unsigned num_views;
       if (process_qualifier_constant(state, loc, "num_views",
                                      this->num_views, &num_views)){
-        if (!validate_view_qualifier(loc, state, num_views)){
-            _mesa_glsl_error(loc, state,
-                  "Invalid num_views specified");
-        }
+         if (!validate_view_qualifier(loc, state, num_views)){
+            _mesa_glsl_error(loc, state, "Invalid num_views specified");
+         }
+         state->view_mask = BITFIELD_MASK(num_views);
       }
    }
 

src/compiler/glsl/gl_nir_linker.c

@@ -2722,6 +2722,7 @@ link_intrastage_shaders(void *mem_ctx,
 {
    bool arb_fragment_coord_conventions_enable = false;
    bool KHR_shader_subgroup_basic_enable = false;
+   int32_t view_mask = -1;
 
    /* Check that global variables defined in multiple shaders are consistent.
     */
@@ -2736,6 +2737,14 @@ link_intrastage_shaders(void *mem_ctx,
          arb_fragment_coord_conventions_enable = true;
       if (shader_list[i]->KHR_shader_subgroup_basic_enable)
          KHR_shader_subgroup_basic_enable = true;
+
+      if (view_mask != -1 && view_mask != shader_list[i]->view_mask) {
+         linker_error(prog, "vertex shader defined with "
+                        "conflicting num_views (%d and %d)\n",
+                        ffs(view_mask) - 1, ffs(shader_list[i]->view_mask) - 1);
+         return NULL;
+      }
+      view_mask = shader_list[i]->view_mask;
    }
 
    if (!prog->data->LinkStatus)
@@ -2833,6 +2842,7 @@ link_intrastage_shaders(void *mem_ctx,
 
    link_layer_viewport_relative_qualifier(prog, gl_prog, shader_list, num_shaders);
 
+   gl_prog->nir->info.view_mask = view_mask;
    gl_prog->nir->info.subgroup_size = KHR_shader_subgroup_basic_enable ?
       SUBGROUP_SIZE_API_CONSTANT : SUBGROUP_SIZE_UNIFORM;
 

src/compiler/glsl/glsl_parser_extras.cpp

@@ -2095,6 +2095,7 @@ set_shader_inout_layout(struct gl_shader *shader,
       break;
    }
 
+   shader->view_mask = state->view_mask;
    shader->bindless_sampler = state->bindless_sampler_specified;
    shader->bindless_image = state->bindless_image_specified;
    shader->bound_sampler = state->bound_sampler_specified;

src/compiler/glsl/glsl_parser_extras.h

@@ -1015,6 +1015,9 @@ struct _mesa_glsl_parse_state {
     * so we can check totals aren't too large.
     */
    unsigned clip_dist_size, cull_dist_size;
+
+   /* for OVR_multiview */
+   uint32_t view_mask;
 };
 
 # define YYLLOC_DEFAULT(Current, Rhs, N)                        \

src/mesa/main/shader_types.h

@@ -233,6 +233,9 @@ struct gl_shader
    /** Global xfb_stride out qualifier if any */
    GLuint TransformFeedbackBufferStride[MAX_FEEDBACK_BUFFERS];
 
+   /* for OVR_multiview */
+   uint32_t view_mask;
+
    struct gl_shader_info info;
 
    /* ARB_gl_spirv related data */