glsl: Store a predicate for whether a built-in signature is available.

For the upcoming built-in function rewrite, we'll need to be able to
answer "Is this built-in function signature available?".

This is actually a somewhat complex question, since it depends on the
language version, GLSL vs. GLSL ES, enabled extensions, and the current
shader stage.

Storing such a set of constraints in a structure would be painful, so
instead we store a function pointer.  When creating a signature, we
simply point to a predicate that inspects _mesa_glsl_parse_state and
answers whether the signature is available in the current shader.

Unfortunately, IR reader doesn't actually know when built-in functions
are available, so this patch makes it lie and say that they're always
present.  This allows us to hook up the new functionality; it just won't
be useful until real data is populated.  In the meantime, the existing
profile mechanism ensures built-ins are available in the right places.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Matt Turner <[email protected]>
Reviewed-by: Paul Berry <[email protected]>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index b45e6cbd831..d785259cc86 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -591,6 +591,11 @@ public:
    const glsl_type *interface_type;
 };
 
+/**
+ * A function that returns whether a built-in function is available in the
+ * current shading language (based on version, ES or desktop, and extensions).
+ */
+typedef bool (*builtin_available_predicate)(const _mesa_glsl_parse_state *);
 
 /*@{*/
 /**
@@ -602,7 +607,8 @@ class ir_function_signature : public ir_instruction {
     * an ir_function.
     */
 public:
-   ir_function_signature(const glsl_type *return_type);
+   ir_function_signature(const glsl_type *return_type,
+                         builtin_available_predicate builtin_info = NULL);
 
    virtual ir_function_signature *clone(void *mem_ctx,
 					struct hash_table *ht) const;
@@ -684,6 +690,12 @@ public:
    struct exec_list body;
 
 private:
+   /**
+    * A function pointer to a predicate that answers whether a built-in
+    * function is available in the current shader.  NULL if not a built-in.
+    */
+   builtin_available_predicate builtin_info;
+
    /** Function of which this signature is one overload. */
    class ir_function *_function;