glsl2: Define new ir_discard instruction.

src/glsl/ir.h

@@ -793,6 +793,33 @@ private:
    /** Loop containing this break instruction. */
    ir_loop *loop;
 };
+
+/**
+ * IR instruction representing discard statements.
+ */
+class ir_discard : public ir_jump {
+public:
+   ir_discard()
+   {
+      this->condition = NULL;
+   }
+
+   ir_discard(ir_rvalue *cond)
+   {
+      this->condition = cond;
+   }
+
+   virtual ir_instruction *clone(struct hash_table *ht) const;
+
+   virtual void accept(ir_visitor *v)
+   {
+      v->visit(this);
+   }
+
+   virtual ir_visitor_status accept(ir_hierarchical_visitor *);
+
+   ir_rvalue *condition;
+};
 /*@}*/
 
 

src/glsl/ir_clone.cpp

@@ -74,6 +74,18 @@ ir_return::clone(struct hash_table *ht) const
    return new(ctx) ir_return(new_value);
 }
 
+ir_instruction *
+ir_discard::clone(struct hash_table *ht) const
+{
+   void *ctx = talloc_parent(this);
+   ir_rvalue *new_condition = NULL;
+
+   if (this->condition != NULL)
+      new_condition = (ir_rvalue *) this->condition->clone(ht);
+
+   return new(ctx) ir_discard(new_condition);
+}
+
 ir_instruction *
 ir_loop_jump::clone(struct hash_table *ht) const
 {

src/glsl/ir_constant_expression.cpp

@@ -75,6 +75,7 @@ public:
    virtual void visit(ir_constant *);
    virtual void visit(ir_call *);
    virtual void visit(ir_return *);
+   virtual void visit(ir_discard *);
    virtual void visit(ir_if *);
    virtual void visit(ir_loop *);
    virtual void visit(ir_loop_jump *);
@@ -647,6 +648,14 @@ ir_constant_visitor::visit(ir_return *ir)
 }
 
 
+void
+ir_constant_visitor::visit(ir_discard *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
 void
 ir_constant_visitor::visit(ir_if *ir)
 {

src/glsl/ir_constant_folding.cpp

@@ -68,6 +68,7 @@ public:
    virtual void visit(ir_constant *);
    virtual void visit(ir_call *);
    virtual void visit(ir_return *);
+   virtual void visit(ir_discard *);
    virtual void visit(ir_if *);
    virtual void visit(ir_loop *);
    virtual void visit(ir_loop_jump *);
@@ -190,6 +191,13 @@ ir_constant_folding_visitor::visit(ir_return *ir)
 }
 
 
+void
+ir_constant_folding_visitor::visit(ir_discard *ir)
+{
+   (void) ir;
+}
+
+
 void
 ir_constant_folding_visitor::visit(ir_if *ir)
 {

src/glsl/ir_hierarchical_visitor.cpp

@@ -242,6 +242,22 @@ ir_hierarchical_visitor::visit_leave(ir_return *ir)
    return visit_continue;
 }
 
+ir_visitor_status
+ir_hierarchical_visitor::visit_enter(ir_discard *ir)
+{
+   if (this->callback != NULL)
+      this->callback(ir, this->data);
+
+   return visit_continue;
+}
+
+ir_visitor_status
+ir_hierarchical_visitor::visit_leave(ir_discard *ir)
+{
+   (void) ir;
+   return visit_continue;
+}
+
 ir_visitor_status
 ir_hierarchical_visitor::visit_enter(ir_if *ir)
 {

src/glsl/ir_hierarchical_visitor.h

@@ -129,6 +129,8 @@ public:
    virtual ir_visitor_status visit_leave(class ir_call *);
    virtual ir_visitor_status visit_enter(class ir_return *);
    virtual ir_visitor_status visit_leave(class ir_return *);
+   virtual ir_visitor_status visit_enter(class ir_discard *);
+   virtual ir_visitor_status visit_leave(class ir_discard *);
    virtual ir_visitor_status visit_enter(class ir_if *);
    virtual ir_visitor_status visit_leave(class ir_if *);
    /*@}*/

src/glsl/ir_hv_accept.cpp

@@ -321,6 +321,23 @@ ir_return::accept(ir_hierarchical_visitor *v)
 }
 
 
+ir_visitor_status
+ir_discard::accept(ir_hierarchical_visitor *v)
+{
+   ir_visitor_status s = v->visit_enter(this);
+   if (s != visit_continue)
+      return (s == visit_continue_with_parent) ? visit_continue : s;
+
+   if (this->condition != NULL) {
+      s = this->condition->accept(v);
+      if (s != visit_continue)
+	 return (s == visit_continue_with_parent) ? visit_continue : s;
+   }
+
+   return v->visit_leave(this);
+}
+
+
 ir_visitor_status
 ir_if::accept(ir_hierarchical_visitor *v)
 {

src/glsl/ir_print_visitor.cpp

@@ -314,6 +314,20 @@ ir_print_visitor::visit(ir_return *ir)
 }
 
 
+void
+ir_print_visitor::visit(ir_discard *ir)
+{
+   printf("(discard ");
+
+   if (ir->condition != NULL) {
+      printf(" ");
+      ir->condition->accept(this);
+   }
+
+   printf(")");
+}
+
+
 void
 ir_print_visitor::visit(ir_if *ir)
 {

src/glsl/ir_print_visitor.h

@@ -69,6 +69,7 @@ public:
    virtual void visit(ir_constant *);
    virtual void visit(ir_call *);
    virtual void visit(ir_return *);
+   virtual void visit(ir_discard *);
    virtual void visit(ir_if *);
    virtual void visit(ir_loop *);
    virtual void visit(ir_loop_jump *);

src/glsl/ir_visitor.h

@@ -57,6 +57,7 @@ public:
    virtual void visit(class ir_constant *) = 0;
    virtual void visit(class ir_call *) = 0;
    virtual void visit(class ir_return *) = 0;
+   virtual void visit(class ir_discard *) = 0;
    virtual void visit(class ir_if *) = 0;
    virtual void visit(class ir_loop *) = 0;
    virtual void visit(class ir_loop_jump *) = 0;

src/mesa/shader/ir_to_mesa.cpp

@@ -134,6 +134,7 @@ public:
    virtual void visit(ir_constant *);
    virtual void visit(ir_call *);
    virtual void visit(ir_return *);
+   virtual void visit(ir_discard *);
    virtual void visit(ir_texture *);
    virtual void visit(ir_if *);
    /*@}*/
@@ -1321,6 +1322,13 @@ ir_to_mesa_visitor::visit(ir_return *ir)
    ir->get_value()->accept(this);
 }
 
+void
+ir_to_mesa_visitor::visit(ir_discard *ir)
+{
+   assert(0);
+
+   ir->condition->accept(this);
+}
 
 void
 ir_to_mesa_visitor::visit(ir_if *ir)