Use ir_function::add_signature to create link between function and signature

ir_function_signature now has a pointer back to the ir_function that owns it.

ast_to_hir.cpp

@@ -1530,7 +1530,7 @@ ast_function_definition::hir(exec_list *instructions,
     */
    if (signature == NULL) {
       signature = new ir_function_signature(return_type);
-      f->signatures.push_tail(signature);
+      f->add_signature(signature);
    } else {
       /* Destroy all of the previous parameter information.  The previous
        * parameter information comes from the function prototype, and it can

builtin_function.cpp

@@ -214,7 +214,7 @@ generate_function_instance(ir_function *f,
    ir_variable *declarations[17];
 
    ir_function_signature *const sig = new ir_function_signature(type);
-   f->signatures.push_tail(sig);
+   f->add_signature(sig);
 
    ir_label *const label = new ir_label(name);
    instructions->push_tail(label);

glsl_types.cpp

@@ -129,7 +129,7 @@ glsl_type::generate_constructor_prototype(glsl_symbol_table *symtab) const
    assert(added);
 
    ir_function_signature *const sig = new ir_function_signature(this);
-   f->signatures.push_tail(sig);
+   f->add_signature(sig);
 
    for (unsigned i = 0; i < length; i++) {
       char *const param_name = (char *) malloc(10);
@@ -433,7 +433,7 @@ generate_constructor(glsl_symbol_table *symtab, const struct glsl_type *types,
        * appropriate from-scalars constructor.
        */
       ir_function_signature *const sig = new ir_function_signature(& types[i]);
-      f->signatures.push_tail(sig);
+      f->add_signature(sig);
 
       sig->definition =
 	 generate_constructor_intro(& types[i], 1, & sig->parameters,
@@ -444,7 +444,7 @@ generate_constructor(glsl_symbol_table *symtab, const struct glsl_type *types,
 
 	 ir_function_signature *const vec_sig =
 	    new ir_function_signature(& types[i]);
-	 f->signatures.push_tail(vec_sig);
+	 f->add_signature(vec_sig);
 
 	 vec_sig->definition =
 	    generate_constructor_intro(& types[i], types[i].vector_elements,
@@ -458,7 +458,7 @@ generate_constructor(glsl_symbol_table *symtab, const struct glsl_type *types,
 
 	 ir_function_signature *const mat_sig =
 	    new ir_function_signature(& types[i]);
-	 f->signatures.push_tail(mat_sig);
+	 f->add_signature(mat_sig);
 
 	 mat_sig->definition =
 	    generate_constructor_intro(& types[i],

ir.h

@@ -160,6 +160,12 @@ public:
     * Pointer to the label that begins the function definition.
     */
    ir_label *definition;
+
+private:
+   /** Function of which this signature is one overload. */
+   class ir_function *function;
+
+   friend class ir_function;
 };
 
 
@@ -175,6 +181,12 @@ public:
       v->visit(this);
    }
 
+   void add_signature(ir_function_signature *sig)
+   {
+      sig->function = this;
+      signatures.push_tail(sig);
+   }
+
    /**
     * Find a signature that matches a set of actual parameters.
     */