3 files changed, 5 insertions, 0 deletions
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index 839d5b3fdb4..970d8f3bac0 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1481,6 +1481,7 @@ ir_function_signature::ir_function_signature(const glsl_type *return_type)
 {
    this->ir_type = ir_type_function_signature;
    this->is_builtin = false;
+   this->origin = NULL;
 }
 
 
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index fe950861620..92be063747f 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -572,6 +572,9 @@ private:
    /** Function of which this signature is one overload. */
    class ir_function *_function;
 
+   /** Function signature of which this one is a prototype clone */
+   const ir_function_signature *origin;
+
    friend class ir_function;
 };
 
diff --git a/src/glsl/ir_clone.cpp b/src/glsl/ir_clone.cpp
index 5046ac372a1..591fe7b7756 100644
--- a/src/glsl/ir_clone.cpp
+++ b/src/glsl/ir_clone.cpp
@@ -324,6 +324,7 @@ ir_function_signature::clone_prototype(void *mem_ctx, struct hash_table *ht) con
 
    copy->is_defined = false;
    copy->is_builtin = this->is_builtin;
+   copy->origin = this;
 
    /* Clone the parameter list, but NOT the body.
     */