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25 #ifndef IR_HIERARCHICAL_VISITOR_H
26 #define IR_HIERARCHICAL_VISITOR_H
29 * Enumeration values returned by visit methods to guide processing
31 enum ir_visitor_status
{
32 visit_continue
, /**< Continue visiting as normal. */
33 visit_continue_with_parent
, /**< Don't visit siblings, continue w/parent. */
34 visit_stop
/**< Stop visiting immediately. */
40 * Base class of hierarchical visitors of IR instruction trees
42 * Hierarchical visitors differ from traditional visitors in a couple of
43 * important ways. Rather than having a single \c visit method for each
44 * subclass in the composite, there are three kinds of visit methods.
45 * Leaf-node classes have a traditional \c visit method. Internal-node
46 * classes have a \c visit_enter method, which is invoked just before
47 * processing child nodes, and a \c visit_leave method which is invoked just
48 * after processing child nodes.
50 * In addition, each visit method and the \c accept methods in the composite
51 * have a return value which guides the navigation. Any of the visit methods
52 * can choose to continue visiting the tree as normal (by returning \c
53 * visit_continue), terminate visiting any further nodes immediately (by
54 * returning \c visit_stop), or stop visiting sibling nodes (by returning \c
55 * visit_continue_with_parent).
57 * These two changes combine to allow nagivation of children to be implemented
58 * in the composite's \c accept method. The \c accept method for a leaf-node
59 * class will simply call the \c visit method, as usual, and pass its return
60 * value on. The \c accept method for internal-node classes will call the \c
61 * visit_enter method, call the \c accept method of each child node, and,
62 * finally, call the \c visit_leave method. If any of these return a value
63 * other that \c visit_continue, the correct action must be taken.
65 * The final benefit is that the hierarchical visitor base class need not be
66 * abstract. Default implementations of every \c visit, \c visit_enter, and
67 * \c visit_leave method can be provided. By default each of these methods
68 * simply returns \c visit_continue. This allows a significant reduction in
71 * For more information about hierarchical visitors, see:
73 * http://c2.com/cgi/wiki?HierarchicalVisitorPattern
74 * http://c2.com/cgi/wiki?HierarchicalVisitorDiscussion
77 class ir_hierarchical_visitor
{
79 ir_hierarchical_visitor();
82 * \name Visit methods for leaf-node classes
85 virtual ir_visitor_status
visit(class ir_rvalue
*);
86 virtual ir_visitor_status
visit(class ir_variable
*);
87 virtual ir_visitor_status
visit(class ir_constant
*);
88 virtual ir_visitor_status
visit(class ir_loop_jump
*);
89 virtual ir_visitor_status
visit(class ir_barrier
*);
92 * ir_dereference_variable isn't technically a leaf, but it is treated as a
93 * leaf here for a couple reasons. By not automatically visiting the one
94 * child ir_variable node from the ir_dereference_variable, ir_variable
95 * nodes can always be handled as variable declarations. Code that used
96 * non-hierarchical visitors had to set an "in a dereference" flag to
97 * determine how to handle an ir_variable. By forcing the visitor to
98 * handle the ir_variable within the ir_dereference_variable visitor, this
99 * kludge can be avoided.
101 * In addition, I can envision no use for having separate enter and leave
102 * methods. Anything that could be done in the enter and leave methods
103 * that couldn't just be done in the visit method.
105 virtual ir_visitor_status
visit(class ir_dereference_variable
*);
109 * \name Visit methods for internal-node classes
112 virtual ir_visitor_status
visit_enter(class ir_loop
*);
113 virtual ir_visitor_status
visit_leave(class ir_loop
*);
114 virtual ir_visitor_status
visit_enter(class ir_function_signature
*);
115 virtual ir_visitor_status
visit_leave(class ir_function_signature
*);
116 virtual ir_visitor_status
visit_enter(class ir_function
*);
117 virtual ir_visitor_status
visit_leave(class ir_function
*);
118 virtual ir_visitor_status
visit_enter(class ir_expression
*);
119 virtual ir_visitor_status
visit_leave(class ir_expression
*);
120 virtual ir_visitor_status
visit_enter(class ir_texture
*);
121 virtual ir_visitor_status
visit_leave(class ir_texture
*);
122 virtual ir_visitor_status
visit_enter(class ir_swizzle
*);
123 virtual ir_visitor_status
visit_leave(class ir_swizzle
*);
124 virtual ir_visitor_status
visit_enter(class ir_dereference_array
*);
125 virtual ir_visitor_status
visit_leave(class ir_dereference_array
*);
126 virtual ir_visitor_status
visit_enter(class ir_dereference_record
*);
127 virtual ir_visitor_status
visit_leave(class ir_dereference_record
*);
128 virtual ir_visitor_status
visit_enter(class ir_assignment
*);
129 virtual ir_visitor_status
visit_leave(class ir_assignment
*);
130 virtual ir_visitor_status
visit_enter(class ir_call
*);
131 virtual ir_visitor_status
visit_leave(class ir_call
*);
132 virtual ir_visitor_status
visit_enter(class ir_return
*);
133 virtual ir_visitor_status
visit_leave(class ir_return
*);
134 virtual ir_visitor_status
visit_enter(class ir_discard
*);
135 virtual ir_visitor_status
visit_leave(class ir_discard
*);
136 virtual ir_visitor_status
visit_enter(class ir_if
*);
137 virtual ir_visitor_status
visit_leave(class ir_if
*);
138 virtual ir_visitor_status
visit_enter(class ir_emit_vertex
*);
139 virtual ir_visitor_status
visit_leave(class ir_emit_vertex
*);
140 virtual ir_visitor_status
visit_enter(class ir_end_primitive
*);
141 virtual ir_visitor_status
visit_leave(class ir_end_primitive
*);
146 * Utility function to process a linked list of instructions with a visitor
148 void run(struct exec_list
*instructions
);
150 /* Some visitors may need to insert new variable declarations and
151 * assignments for portions of a subtree, which means they need a
152 * pointer to the current instruction in the stream, not just their
153 * node in the tree rooted at that instruction.
155 * This is implemented by visit_list_elements -- if the visitor is
156 * not called by it, nothing good will happen.
158 class ir_instruction
*base_ir
;
161 * Callback function that is invoked on entry to each node visited.
164 * Visitor classes derived from \c ir_hierarchical_visitor \b may \b not
165 * invoke this function. This can be used, for example, to cause the
166 * callback to be invoked on every node type except one.
168 void (*callback_enter
)(class ir_instruction
*ir
, void *data
);
171 * Callback function that is invoked on exit of each node visited.
174 * Visitor classes derived from \c ir_hierarchical_visitor \b may \b not
175 * invoke this function. This can be used, for example, to cause the
176 * callback to be invoked on every node type except one.
178 void (*callback_leave
)(class ir_instruction
*ir
, void *data
);
181 * Extra data parameter passed to the per-node callback_enter function
186 * Extra data parameter passed to the per-node callback_leave function
191 * Currently in the LHS of an assignment?
193 * This is set and cleared by the \c ir_assignment::accept method.
198 void visit_tree(ir_instruction
*ir
,
199 void (*callback_enter
)(class ir_instruction
*ir
, void *data
),
201 void (*callback_leave
)(class ir_instruction
*ir
, void *data
) = NULL
,
202 void *data_leave
= NULL
);
204 ir_visitor_status
visit_list_elements(ir_hierarchical_visitor
*v
, exec_list
*l
,
205 bool statement_list
= true);
206 #endif /* __cplusplus */
208 #endif /* IR_HIERARCHICAL_VISITOR_H */