mesa: glGetProgramResourceLocation

Patch adds required helper functions to shaderapi.h and
the actual implementation.

corresponding Piglit test:
   arb_program_interface_query-resource-location

The added functionality can be tested by tests for following
functions that are refactored by later patches:

   GetAttribLocation
   GetUniformLocation
   GetFragDataLocation

v2: code cleanup, changes to array element
    syntax checking (Ilia Mirkin)

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Martin Peres <martin.peres@linux.intel.com>

src/mesa/main/program_resource.c

@@ -278,11 +278,90 @@ _mesa_GetProgramResourceiv(GLuint program, GLenum programInterface,
 {
 }
 
+/**
+ * Function verifies syntax of given name for GetProgramResourceLocation
+ * and GetProgramResourceLocationIndex for the following cases:
+ *
+ * "array element portion of a string passed to GetProgramResourceLocation
+ * or GetProgramResourceLocationIndex must not have, a "+" sign, extra
+ * leading zeroes, or whitespace".
+ *
+ * Check is written to be compatible with GL_ARB_array_of_arrays.
+ */
+static bool
+invalid_array_element_syntax(const GLchar *name)
+{
+   char *first = strchr(name, '[');
+   char *last = strrchr(name, '[');
+
+   if (!first)
+      return false;
+
+   /* No '+' or ' ' allowed anywhere. */
+   if (strchr(first, '+') || strchr(first, ' '))
+      return true;
+
+   /* Check that last array index is 0. */
+   if (last[1] == '0' && last[2] != ']')
+      return true;
+
+   return false;
+}
+
+static struct gl_shader_program *
+lookup_linked_program(GLuint program, const char *caller)
+{
+   GET_CURRENT_CONTEXT(ctx);
+   struct gl_shader_program *prog =
+      _mesa_lookup_shader_program_err(ctx, program, caller);
+
+   if (!prog)
+      return NULL;
+
+   if (prog->LinkStatus == GL_FALSE) {
+      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(program not linked)",
+                  caller);
+      return NULL;
+   }
+   return prog;
+}
+
 GLint GLAPIENTRY
 _mesa_GetProgramResourceLocation(GLuint program, GLenum programInterface,
                                  const GLchar *name)
 {
-   return -1;
+   GET_CURRENT_CONTEXT(ctx);
+   struct gl_shader_program *shProg =
+      lookup_linked_program(program, "glGetProgramResourceLocation");
+
+   if (!shProg || !name || invalid_array_element_syntax(name))
+      return -1;
+
+   /* Validate programInterface. */
+   switch (programInterface) {
+   case GL_UNIFORM:
+   case GL_PROGRAM_INPUT:
+   case GL_PROGRAM_OUTPUT:
+      break;
+
+   /* For reference valid cases requiring additional extension support:
+    * GL_ARB_shader_subroutine
+    * GL_ARB_tessellation_shader
+    * GL_ARB_compute_shader
+    */
+   case GL_VERTEX_SUBROUTINE_UNIFORM:
+   case GL_TESS_CONTROL_SUBROUTINE_UNIFORM:
+   case GL_TESS_EVALUATION_SUBROUTINE_UNIFORM:
+   case GL_GEOMETRY_SUBROUTINE_UNIFORM:
+   case GL_FRAGMENT_SUBROUTINE_UNIFORM:
+   case GL_COMPUTE_SUBROUTINE_UNIFORM:
+
+   default:
+      _mesa_error(ctx, GL_INVALID_ENUM, "glGetProgramResourceLocation(%s %s)",
+                  _mesa_lookup_enum_by_nr(programInterface), name);
+   }
+
+   return _mesa_program_resource_location(shProg, programInterface, name);
 }
 
 GLint GLAPIENTRY

src/mesa/main/shader_query.cpp

@@ -754,3 +754,70 @@ _mesa_get_program_resource_name(struct gl_shader_program *shProg,
    }
    return true;
 }
+
+static GLint
+program_resource_location(struct gl_shader_program *shProg,
+                          struct gl_program_resource *res, const char *name)
+{
+   unsigned index, offset;
+   int array_index = -1;
+
+   if (res->Type == GL_PROGRAM_INPUT || res->Type == GL_PROGRAM_OUTPUT) {
+      array_index = array_index_of_resource(res, name);
+      if (array_index < 0)
+         return -1;
+   }
+
+   /* VERT_ATTRIB_GENERIC0 and FRAG_RESULT_DATA0 are decremented as these
+    * offsets are used internally to differentiate between built-in attributes
+    * and user-defined attributes.
+    */
+   switch (res->Type) {
+   case GL_PROGRAM_INPUT:
+      return RESOURCE_VAR(res)->data.location + array_index - VERT_ATTRIB_GENERIC0;
+   case GL_PROGRAM_OUTPUT:
+      return RESOURCE_VAR(res)->data.location + array_index - FRAG_RESULT_DATA0;
+   case GL_UNIFORM:
+      index = _mesa_get_uniform_location(shProg, name, &offset);
+
+      if (index == GL_INVALID_INDEX)
+         return -1;
+
+      /* From the GL_ARB_uniform_buffer_object spec:
+       *
+       *     "The value -1 will be returned if <name> does not correspond to an
+       *     active uniform variable name in <program>, if <name> is associated
+       *     with a named uniform block, or if <name> starts with the reserved
+       *     prefix "gl_"."
+       */
+      if (RESOURCE_UNI(res)->block_index != -1 ||
+          RESOURCE_UNI(res)->atomic_buffer_index != -1)
+         return -1;
+
+      /* location in remap table + array element offset */
+      return RESOURCE_UNI(res)->remap_location + offset;
+
+   default:
+      return -1;
+   }
+}
+
+/**
+ * Function implements following location queries:
+ *    glGetAttribLocation
+ *    glGetFragDataLocation
+ *    glGetUniformLocation
+ */
+GLint
+_mesa_program_resource_location(struct gl_shader_program *shProg,
+                                GLenum interface, const char *name)
+{
+   struct gl_program_resource *res =
+      _mesa_program_resource_find_name(shProg, interface, name);
+
+   /* Resource not found. */
+   if (!res)
+      return -1;
+
+   return program_resource_location(shProg, res, name);
+}

src/mesa/main/shaderapi.h

@@ -244,6 +244,10 @@ _mesa_get_program_resource_name(struct gl_shader_program *shProg,
                                 GLsizei bufSize, GLsizei *length,
                                 GLchar *name, const char *caller);
 
+extern GLint
+_mesa_program_resource_location(struct gl_shader_program *shProg,
+                                GLenum interface, const char *name);
+
 #ifdef __cplusplus
 }
 #endif