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