nir: Add a pass to gather info from the shader

This pass fills out a bunch of the fields in nir_shader_info by inspecting
the shader.

src/glsl/Makefile.sources

@@ -32,6 +32,7 @@ NIR_FILES = \
 	nir/nir_control_flow_private.h \
 	nir/nir_dominance.c \
 	nir/nir_from_ssa.c \
+	nir/nir_gather_info.c \
 	nir/nir_gs_count_vertices.c \
 	nir/nir_intrinsics.c \
 	nir/nir_intrinsics.h \

src/glsl/nir/nir.h

@@ -1939,6 +1939,8 @@ void nir_lower_outputs_to_temporaries(nir_shader *shader);
 
 void nir_lower_outputs_to_temporaries(nir_shader *shader);
 
+void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
+
 void nir_assign_var_locations(struct exec_list *var_list,
                               unsigned *size,
                               int (*type_size)(const struct glsl_type *));

src/glsl/nir/nir_gather_info.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * 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 (including the next
+ * paragraph) 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 "nir.h"
+
+static void
+gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader)
+{
+   switch (instr->intrinsic) {
+   case nir_intrinsic_discard:
+      assert(shader->stage == MESA_SHADER_FRAGMENT);
+      shader->info.fs.uses_discard = true;
+      break;
+
+   case nir_intrinsic_load_front_face:
+   case nir_intrinsic_load_vertex_id:
+   case nir_intrinsic_load_vertex_id_zero_base:
+   case nir_intrinsic_load_base_vertex:
+   case nir_intrinsic_load_instance_id:
+   case nir_intrinsic_load_sample_id:
+   case nir_intrinsic_load_sample_pos:
+   case nir_intrinsic_load_sample_mask_in:
+   case nir_intrinsic_load_primitive_id:
+   case nir_intrinsic_load_invocation_id:
+   case nir_intrinsic_load_local_invocation_id:
+   case nir_intrinsic_load_work_group_id:
+   case nir_intrinsic_load_num_work_groups:
+      shader->info.system_values_read |=
+         (1 << nir_system_value_from_intrinsic(instr->intrinsic));
+      break;
+   default:
+      break;
+   }
+}
+
+static void
+gather_tex_info(nir_tex_instr *instr, nir_shader *shader)
+{
+   if (instr->op == nir_texop_tg4)
+      shader->info.uses_texture_gather = true;
+}
+
+static bool
+gather_info_block(nir_block *block, void *shader)
+{
+   nir_foreach_instr(block, instr) {
+      switch (instr->type) {
+      case nir_instr_type_intrinsic:
+         gather_intrinsic_info(nir_instr_as_intrinsic(instr), shader);
+         break;
+      case nir_instr_type_tex:
+         gather_tex_info(nir_instr_as_tex(instr), shader);
+         break;
+      case nir_instr_type_call:
+         assert(!"nir_shader_gather_info only works if functions are inlined");
+         break;
+      default:
+         break;
+      }
+   }
+
+   return true;
+}
+
+void
+nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint)
+{
+   shader->info.inputs_read = 0;
+   foreach_list_typed(nir_variable, var, node, &shader->inputs)
+      shader->info.inputs_read |= (1ull << var->data.location);
+
+   shader->info.outputs_written = 0;
+   foreach_list_typed(nir_variable, var, node, &shader->outputs)
+      shader->info.outputs_written |= (1ull << var->data.location);
+
+   shader->info.system_values_read = 0;
+   foreach_list_typed(nir_variable, var, node, &shader->system_values)
+      shader->info.system_values_read |= (1ull << var->data.location);
+
+   nir_foreach_block(entrypoint, gather_info_block, shader);
+}