glsl: Use ir_rvalue to represent generic error_type values.

Currently, ir_call can be used as either a statement (for void
functions) or a value (for non-void functions).  This is rather awkward,
as it's the only class that can be used in both forms.

A number of places use ir_call::get_error_instruction() to construct a
generic value of error_type.  If ir_call is to become a statement, it
can no longer serve this purpose.

Unfortunately, none of our classes are particularly well suited for
this, and creating a new one would be rather aggrandizing.  So, this
patch introduces ir_rvalue::error_value(), a static method that creates
an instance of the base class, ir_rvalue.  This has the nice property
that you can't accidentally try and access uninitialized fields (as it
doesn't have any).  The downside is that the base class is no longer
abstract.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/glsl/ast_function.cpp

@@ -602,7 +602,7 @@ process_array_constructor(exec_list *instructions,
 		       "parameter%s",
 		       (constructor_type->length != 0) ? "at least" : "exactly",
 		       min_param, (min_param <= 1) ? "" : "s");
-      return ir_call::get_error_instruction(ctx);
+      return ir_rvalue::error_value(ctx);
    }
 
    if (constructor_type->length == 0) {
@@ -1239,7 +1239,7 @@ ast_function_expression::hir(exec_list *instructions,
 	 _mesa_glsl_error(& loc, state, "unknown type `%s' (structure name "
 			  "may be shadowed by a variable with the same name)",
 			  type->type_name);
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
       }
 
 
@@ -1248,14 +1248,14 @@ ast_function_expression::hir(exec_list *instructions,
       if (constructor_type->is_sampler()) {
 	 _mesa_glsl_error(& loc, state, "cannot construct sampler type `%s'",
 			  constructor_type->name);
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
       }
 
       if (constructor_type->is_array()) {
 	 if (state->language_version <= 110) {
 	    _mesa_glsl_error(& loc, state,
 			     "array constructors forbidden in GLSL 1.10");
-	    return ir_call::get_error_instruction(ctx);
+	    return ir_rvalue::error_value(ctx);
 	 }
 
 	 return process_array_constructor(instructions, constructor_type,
@@ -1286,7 +1286,7 @@ ast_function_expression::hir(exec_list *instructions,
 				"insufficient parameters to constructor "
 				"for `%s'",
 				constructor_type->name);
-	       return ir_call::get_error_instruction(ctx);
+	       return ir_rvalue::error_value(ctx);
 	    }
 
 	    if (apply_implicit_conversion(constructor_type->fields.structure[i].type,
@@ -1300,7 +1300,7 @@ ast_function_expression::hir(exec_list *instructions,
 				constructor_type->fields.structure[i].name,
 				ir->type->name,
 				constructor_type->fields.structure[i].type->name);
-	       return ir_call::get_error_instruction(ctx);;
+	       return ir_rvalue::error_value(ctx);;
 	    }
 
 	    node = node->next;
@@ -1309,7 +1309,7 @@ ast_function_expression::hir(exec_list *instructions,
 	 if (!node->is_tail_sentinel()) {
 	    _mesa_glsl_error(&loc, state, "too many parameters in constructor "
 			     "for `%s'", constructor_type->name);
-	    return ir_call::get_error_instruction(ctx);
+	    return ir_rvalue::error_value(ctx);
 	 }
 
 	 ir_rvalue *const constant =
@@ -1323,7 +1323,7 @@ ast_function_expression::hir(exec_list *instructions,
       }
 
       if (!constructor_type->is_numeric() && !constructor_type->is_boolean())
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
 
       /* Total number of components of the type being constructed. */
       const unsigned type_components = constructor_type->components();
@@ -1350,14 +1350,14 @@ ast_function_expression::hir(exec_list *instructions,
 	    _mesa_glsl_error(& loc, state, "too many parameters to `%s' "
 			     "constructor",
 			     constructor_type->name);
-	    return ir_call::get_error_instruction(ctx);
+	    return ir_rvalue::error_value(ctx);
 	 }
 
 	 if (!result->type->is_numeric() && !result->type->is_boolean()) {
 	    _mesa_glsl_error(& loc, state, "cannot construct `%s' from a "
 			     "non-numeric data type",
 			     constructor_type->name);
-	    return ir_call::get_error_instruction(ctx);
+	    return ir_rvalue::error_value(ctx);
 	 }
 
 	 /* Count the number of matrix and nonmatrix parameters.  This
@@ -1382,7 +1382,7 @@ ast_function_expression::hir(exec_list *instructions,
 	 _mesa_glsl_error(& loc, state, "cannot construct `%s' from a "
 			  "matrix in GLSL 1.10",
 			  constructor_type->name);
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
       }
 
       /* From page 50 (page 56 of the PDF) of the GLSL 1.50 spec:
@@ -1396,7 +1396,7 @@ ast_function_expression::hir(exec_list *instructions,
 	 _mesa_glsl_error(& loc, state, "for matrix `%s' constructor, "
 			  "matrix must be only parameter",
 			  constructor_type->name);
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
       }
 
       /* From page 28 (page 34 of the PDF) of the GLSL 1.10 spec:
@@ -1410,7 +1410,7 @@ ast_function_expression::hir(exec_list *instructions,
 	 _mesa_glsl_error(& loc, state, "too few components to construct "
 			  "`%s'",
 			  constructor_type->name);
-	 return ir_call::get_error_instruction(ctx);
+	 return ir_rvalue::error_value(ctx);
       }
 
       /* Later, we cast each parameter to the same base type as the
@@ -1505,10 +1505,10 @@ ast_function_expression::hir(exec_list *instructions,
       ir_rvalue *value = NULL;
       if (sig == NULL) {
 	 no_matching_function_error(func_name, &loc, &actual_parameters, state);
-	 value = ir_call::get_error_instruction(ctx);
+	 value = ir_rvalue::error_value(ctx);
       } else if (!verify_parameter_modes(state, sig, actual_parameters, this->expressions)) {
 	 /* an error has already been emitted */
-	 value = ir_call::get_error_instruction(ctx);
+	 value = ir_rvalue::error_value(ctx);
       } else {
 	 value = generate_call(instructions, sig, &loc, &actual_parameters,
 			       &call, state);
@@ -1517,5 +1517,5 @@ ast_function_expression::hir(exec_list *instructions,
       return value;
    }
 
-   return ir_call::get_error_instruction(ctx);
+   return ir_rvalue::error_value(ctx);
 }

src/glsl/ast_to_hir.cpp

@@ -1699,7 +1699,7 @@ ast_expression::hir(exec_list *instructions,
 	 _mesa_glsl_error(& loc, state, "`%s' undeclared",
 			  this->primary_expression.identifier);
 
-	 result = ir_call::get_error_instruction(ctx);
+	 result = ir_rvalue::error_value(ctx);
 	 error_emitted = true;
       }
       break;

src/glsl/hir_field_selection.cpp

@@ -98,5 +98,5 @@ _mesa_ast_field_selection_to_hir(const ast_expression *expr,
 		       expr->primary_expression.identifier);
    }
 
-   return result ? result : ir_call::get_error_instruction(ctx);
+   return result ? result : ir_rvalue::error_value(ctx);
 }

src/glsl/ir.cpp

@@ -1458,13 +1458,13 @@ ir_function::has_user_signature()
 }
 
 
-ir_call *
-ir_call::get_error_instruction(void *ctx)
+ir_rvalue *
+ir_rvalue::error_value(void *mem_ctx)
 {
-   ir_call *call = new(ctx) ir_call;
+   ir_rvalue *v = new(mem_ctx) ir_rvalue;
 
-   call->type = glsl_type::error_type;
-   return call;
+   v->type = glsl_type::error_type;
+   return v;
 }
 
 void

src/glsl/ir.h

@@ -132,11 +132,21 @@ protected:
 };
 
 
+/**
+ * The base class for all "values"/expression trees.
+ */
 class ir_rvalue : public ir_instruction {
 public:
-   virtual ir_rvalue *clone(void *mem_ctx, struct hash_table *) const = 0;
+   virtual ir_rvalue *clone(void *mem_ctx, struct hash_table *) const;
 
-   virtual ir_constant *constant_expression_value() = 0;
+   virtual void accept(ir_visitor *v)
+   {
+      v->visit(this);
+   }
+
+   virtual ir_visitor_status accept(ir_hierarchical_visitor *);
+
+   virtual ir_constant *constant_expression_value();
 
    virtual ir_rvalue * as_rvalue()
    {
@@ -209,6 +219,14 @@ public:
     */
    virtual bool is_negative_one() const;
 
+
+   /**
+    * Return a generic value of error_type.
+    *
+    * Allocation will be performed with 'mem_ctx' as ralloc owner.
+    */
+   static ir_rvalue *error_value(void *mem_ctx);
+
 protected:
    ir_rvalue();
 };
@@ -1029,13 +1047,6 @@ public:
 
    virtual ir_visitor_status accept(ir_hierarchical_visitor *);
 
-   /**
-    * Get a generic ir_call object when an error occurs
-    *
-    * Any allocation will be performed with 'ctx' as ralloc owner.
-    */
-   static ir_call *get_error_instruction(void *ctx);
-
    /**
     * Get an iterator for the set of acutal parameters
     */
@@ -1078,12 +1089,6 @@ public:
    bool use_builtin;
 
 private:
-   ir_call()
-      : callee(NULL)
-   {
-      this->ir_type = ir_type_call;
-   }
-
    ir_function_signature *callee;
 };
 

src/glsl/ir_clone.cpp

@@ -27,6 +27,13 @@
 #include "glsl_types.h"
 #include "program/hash_table.h"
 
+ir_rvalue *
+ir_rvalue::clone(void *mem_ctx, struct hash_table *ht) const
+{
+   /* The only possible instantiation is the generic error value. */
+   return error_value(mem_ctx);
+}
+
 /**
  * Duplicate an IR variable
  *
@@ -160,9 +167,6 @@ ir_loop::clone(void *mem_ctx, struct hash_table *ht) const
 ir_call *
 ir_call::clone(void *mem_ctx, struct hash_table *ht) const
 {
-   if (this->type == glsl_type::error_type)
-      return ir_call::get_error_instruction(mem_ctx);
-
    exec_list new_parameters;
 
    foreach_iter(exec_list_iterator, iter, this->actual_parameters) {

src/glsl/ir_constant_expression.cpp

@@ -70,6 +70,13 @@ dot(ir_constant *op0, ir_constant *op1)
    return result;
 }
 
+ir_constant *
+ir_rvalue::constant_expression_value()
+{
+   assert(this->type->is_error());
+   return NULL;
+}
+
 ir_constant *
 ir_expression::constant_expression_value()
 {

src/glsl/ir_hierarchical_visitor.cpp

@@ -32,6 +32,15 @@ ir_hierarchical_visitor::ir_hierarchical_visitor()
    this->in_assignee = false;
 }
 
+ir_visitor_status
+ir_hierarchical_visitor::visit(ir_rvalue *ir)
+{
+   if (this->callback != NULL)
+      this->callback(ir, this->data);
+
+   return visit_continue;
+}
+
 ir_visitor_status
 ir_hierarchical_visitor::visit(ir_variable *ir)
 {

src/glsl/ir_hierarchical_visitor.h

@@ -82,6 +82,7 @@ public:
     * \name Visit methods for leaf-node classes
     */
    /*@{*/
+   virtual ir_visitor_status visit(class ir_rvalue *);
    virtual ir_visitor_status visit(class ir_variable *);
    virtual ir_visitor_status visit(class ir_constant *);
    virtual ir_visitor_status visit(class ir_loop_jump *);

src/glsl/ir_hv_accept.cpp

@@ -65,6 +65,13 @@ visit_list_elements(ir_hierarchical_visitor *v, exec_list *l,
 }
 
 
+ir_visitor_status
+ir_rvalue::accept(ir_hierarchical_visitor *v)
+{
+   return v->visit(this);
+}
+
+
 ir_visitor_status
 ir_variable::accept(ir_hierarchical_visitor *v)
 {

src/glsl/ir_print_visitor.cpp

@@ -135,6 +135,10 @@ print_type(const glsl_type *t)
    }
 }
 
+void ir_print_visitor::visit(ir_rvalue *ir)
+{
+   printf("error");
+}
 
 void ir_print_visitor::visit(ir_variable *ir)
 {

src/glsl/ir_print_visitor.h

@@ -54,6 +54,7 @@ public:
     * the hierarchy should not have \c visit methods.
     */
    /*@{*/
+   virtual void visit(ir_rvalue *);
    virtual void visit(ir_variable *);
    virtual void visit(ir_function_signature *);
    virtual void visit(ir_function *);

src/glsl/ir_visitor.h

@@ -44,6 +44,7 @@ public:
     * the hierarchy should not have \c visit methods.
     */
    /*@{*/
+   virtual void visit(class ir_rvalue *) { assert(!"unhandled error_type"); }
    virtual void visit(class ir_variable *) = 0;
    virtual void visit(class ir_function_signature *) = 0;
    virtual void visit(class ir_function *) = 0;