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 <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 20 insertions, 15 deletions

diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 1faae3c7259..811eac08878 100644
--- a/src/glsl/ir.h
+++ b/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();
 };
@@ -1030,13 +1048,6 @@ 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
     */
    exec_list_iterator iterator()
@@ -1078,12 +1089,6 @@ public:
    bool use_builtin;
 
 private:
-   ir_call()
-      : callee(NULL)
-   {
-      this->ir_type = ir_type_call;
-   }
-
    ir_function_signature *callee;
 };