glsl: move some compiler code out of st

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22846>

src/compiler/glsl/gl_nir_linker.c

@@ -22,6 +22,7 @@
  */
 
 #include "nir.h"
+#include "nir_builder.h"
 #include "gl_nir.h"
 #include "gl_nir_linker.h"
 #include "linker_util.h"
@@ -125,6 +126,39 @@ gl_nir_opts(nir_shader *nir)
    NIR_PASS_V(nir, nir_lower_var_copies);
 }
 
+bool
+gl_nir_can_add_pointsize_to_program(const struct gl_constants *consts,
+                                    struct gl_program *prog)
+{
+   nir_shader *nir = prog->nir;
+   if (!nir)
+      return true; /* fixedfunction */
+
+   assert(nir->info.stage == MESA_SHADER_VERTEX ||
+          nir->info.stage == MESA_SHADER_TESS_EVAL ||
+          nir->info.stage == MESA_SHADER_GEOMETRY);
+   if (nir->info.outputs_written & VARYING_BIT_PSIZ)
+      return false;
+
+   unsigned max_components = nir->info.stage == MESA_SHADER_GEOMETRY ?
+                             consts->MaxGeometryTotalOutputComponents :
+                             consts->Program[nir->info.stage].MaxOutputComponents;
+   unsigned num_components = 0;
+   unsigned needed_components = nir->info.stage == MESA_SHADER_GEOMETRY ? nir->info.gs.vertices_out : 1;
+   nir_foreach_shader_out_variable(var, nir) {
+      num_components += glsl_count_dword_slots(var->type, false);
+   }
+
+   /* Ensure that there is enough attribute space to emit at least one primitive */
+   if (nir->info.stage == MESA_SHADER_GEOMETRY) {
+      if (num_components + needed_components > consts->Program[nir->info.stage].MaxOutputComponents)
+         return false;
+      num_components *= nir->info.gs.vertices_out;
+   }
+
+   return num_components + needed_components <= max_components;
+}
+
 static void
 gl_nir_link_opts(nir_shader *producer, nir_shader *consumer)
 {
@@ -752,6 +786,44 @@ nir_build_program_resource_list(const struct gl_constants *consts,
    _mesa_set_destroy(resource_set, NULL);
 }
 
+/* - create a gl_PointSize variable
+ * - find every gl_Position write
+ * - store 1.0 to gl_PointSize after every gl_Position write
+ */
+void
+gl_nir_add_point_size(nir_shader *nir)
+{
+   nir_variable *psiz = nir_create_variable_with_location(nir, nir_var_shader_out,
+                                                          VARYING_SLOT_PSIZ, glsl_float_type());
+   psiz->data.how_declared = nir_var_hidden;
+
+   nir_function_impl *impl = nir_shader_get_entrypoint(nir);
+   nir_builder b = nir_builder_create(impl);
+   bool found = false;
+   nir_foreach_block_safe(block, impl) {
+      nir_foreach_instr_safe(instr, block) {
+         if (instr->type == nir_instr_type_intrinsic) {
+            nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+            if (intr->intrinsic == nir_intrinsic_store_deref ||
+                intr->intrinsic == nir_intrinsic_copy_deref) {
+               nir_variable *var = nir_intrinsic_get_var(intr, 0);
+               if (var->data.location == VARYING_SLOT_POS) {
+                  b.cursor = nir_after_instr(instr);
+                  nir_deref_instr *deref = nir_build_deref_var(&b, psiz);
+                  nir_store_deref(&b, deref, nir_imm_float(&b, 1.0), BITFIELD_BIT(0));
+                  found = true;
+               }
+            }
+         }
+      }
+   }
+   if (!found) {
+      b.cursor = nir_before_cf_list(&impl->body);
+      nir_deref_instr *deref = nir_build_deref_var(&b, psiz);
+      nir_store_deref(&b, deref, nir_imm_float(&b, 1.0), BITFIELD_BIT(0));
+   }
+}
+
 bool
 gl_nir_link_spirv(const struct gl_constants *consts,
                   struct gl_shader_program *prog,

src/compiler/glsl/gl_nir_linker.h

@@ -38,6 +38,7 @@ struct gl_constants;
 struct gl_extensions;
 struct gl_linked_shader;
 struct gl_shader_program;
+struct gl_program;
 struct gl_transform_feedback_info;
 struct xfb_decl;
 struct nir_xfb_info;
@@ -113,6 +114,13 @@ void gl_nir_link_assign_xfb_resources(const struct gl_constants *consts,
 
 bool gl_nir_link_uniform_blocks(struct gl_shader_program *prog);
 
+bool
+gl_nir_can_add_pointsize_to_program(const struct gl_constants *consts,
+                                    struct gl_program *prog);
+
+void
+gl_nir_add_point_size(struct nir_shader *nir);
+
 bool lower_packed_varying_needs_lowering(nir_shader *shader, nir_variable *var,
                                          bool xfb_enabled,
                                          bool disable_xfb_packing,