[Mesa-dev] [PATCH V3 6/6] mesa: simplify sampler indexing

[Timothy Arceri]

Removes another dependency on the UniformHash hash table.
---
 src/mesa/program/sampler.cpp | 123 +++++++++++++++++++------------------------
 1 file changed, 53 insertions(+), 70 deletions(-)

diff --git a/src/mesa/program/sampler.cpp b/src/mesa/program/sampler.cpp
index ea3024d..01150fa 100644
--- a/src/mesa/program/sampler.cpp
+++ b/src/mesa/program/sampler.cpp
@@ -35,71 +35,56 @@
 #include "program/program.h"
 
 
-class get_sampler_name : public ir_hierarchical_visitor
+/* Calculate the sampler index based on array indicies and also
+ * calculate the base uniform location for struct members.
+ */
+static void
+calc_sampler_offsets(ir_dereference *deref, unsigned *array_elements,
+                     unsigned *location_offset, unsigned *sampler_offset,
+                     struct gl_shader_program *shader_program)
 {
-public:
-   get_sampler_name(ir_dereference *last,
-		    struct gl_shader_program *shader_program)
-   {
-      this->mem_ctx = ralloc_context(NULL);
-      this->shader_program = shader_program;
-      this->name = NULL;
-      this->offset = 0;
-      this->last = last;
-   }
+   switch (deref->ir_type) {
+   case ir_type_dereference_array: {
+      ir_dereference_array *ir = deref->as_dereference_array();
+      calc_sampler_offsets(ir->array->as_dereference(), array_elements,
+                           location_offset, sampler_offset, shader_program);
 
-   ~get_sampler_name()
-   {
-      ralloc_free(this->mem_ctx);
+      ir_constant *index = ir->array_index->as_constant();
+      if (index) {
+         *sampler_offset += index->value.i[0] * *array_elements;
+      } else {
+        /* GLSL 1.10 and 1.20 allowed variable sampler array indices,
+         * while GLSL 1.30 requires that the array indices be
+         * constant integer expressions.  We don't expect any driver
+         * to actually work with a really variable array index, so
+         * all that would work would be an unrolled loop counter that ends
+         * up being constant above.
+         */
+        ralloc_strcat(&shader_program->InfoLog,
+                      "warning: Variable sampler array index unsupported.\n"
+                      "This feature of the language was removed in GLSL 1.20 "
+                      "and is unlikely to be supported for 1.10 in Mesa.\n");
+      }
+      break;
    }
 
-   virtual ir_visitor_status visit(ir_dereference_variable *ir)
-   {
-      this->name = ir->var->name;
-      return visit_continue;
+   case ir_type_dereference_record: {
+      ir_dereference_record *ir = deref->as_dereference_record();
+      *location_offset += ir->record->type->field_index(ir->field);
+      calc_sampler_offsets(ir->record->as_dereference(), array_elements,
+                           location_offset, sampler_offset, shader_program);
+      break;
    }
 
-   virtual ir_visitor_status visit_leave(ir_dereference_record *ir)
-   {
-      this->name = ralloc_asprintf(mem_ctx, "%s.%s", name, ir->field);
-      return visit_continue;
+   case ir_type_dereference_variable: {
+      return;
    }
 
-   virtual ir_visitor_status visit_leave(ir_dereference_array *ir)
-   {
-      ir_constant *index = ir->array_index->as_constant();
-      int i;
-
-      if (index) {
-	 i = index->value.i[0];
-      } else {
-	 /* GLSL 1.10 and 1.20 allowed variable sampler array indices,
-	  * while GLSL 1.30 requires that the array indices be
-	  * constant integer expressions.  We don't expect any driver
-	  * to actually work with a really variable array index, so
-	  * all that would work would be an unrolled loop counter that ends
-	  * up being constant above.
-	  */
-	 ralloc_strcat(&shader_program->InfoLog,
-		       "warning: Variable sampler array index unsupported.\n"
-		       "This feature of the language was removed in GLSL 1.20 "
-		       "and is unlikely to be supported for 1.10 in Mesa.\n");
-	 i = 0;
-      }
-      if (ir != last) {
-	 this->name = ralloc_asprintf(mem_ctx, "%s[%d]", name, i);
-      } else {
-	 offset = i;
-      }
-      return visit_continue;
+   default:
+      unreachable("Invalid deref type");
+      break;
    }
-
-   struct gl_shader_program *shader_program;
-   const char *name;
-   void *mem_ctx;
-   int offset;
-   ir_dereference *last;
-};
+}
 
 
 int
@@ -107,30 +92,28 @@ _mesa_get_sampler_uniform_value(class ir_dereference *sampler,
 				struct gl_shader_program *shader_program,
 				const struct gl_program *prog)
 {
-   get_sampler_name getname(sampler, shader_program);
-
+   unsigned array_elements = 1;
+   unsigned location_offset = 0;
+   unsigned sampler_offset = 0;
    GLuint shader = _mesa_program_enum_to_shader_stage(prog->Target);
 
-   sampler->accept(&getname);
+   calc_sampler_offsets(sampler, &array_elements, &location_offset,
+                        &sampler_offset, shader_program);
 
-   unsigned location;
-   if (!shader_program->UniformHash->get(location, getname.name)) {
-      linker_error(shader_program,
-		   "failed to find sampler named %s.\n", getname.name);
-      return 0;
-   }
+   unsigned location = sampler->variable_referenced()->data.location +
+      location_offset;
 
-   if (!shader_program->UniformStorage[location].sampler[shader].active) {
+   if (location > shader_program->NumUniformStorage - 1 ||
+       !shader_program->UniformStorage[location].sampler[shader].active) {
       assert(0 && "cannot return a sampler");
       linker_error(shader_program,
-		   "cannot return a sampler named %s, because it is not "
-                   "used in this shader stage. This is a driver bug.\n",
-                   getname.name);
+		   "cannot return a sampler, because it is not "
+                   "used in this shader stage. This is a driver bug.\n");
       return 0;
    }
 
    return shader_program->UniformStorage[location].sampler[shader].index +
-          getname.offset;
+      sampler_offset;
 }
 
 
-- 
2.4.3