1/* -*- c++ -*- */
2/*
3 * Copyright © 2010 Intel Corporation
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
23 */
24
25#pragma once
26#ifndef IR_HIERARCHICAL_VISITOR_H
27#define IR_HIERARCHICAL_VISITOR_H
28
29/**
30 * Enumeration values returned by visit methods to guide processing
31 */
32enum 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. */
36};
37
38
39/**
40 * Base class of hierarchical visitors of IR instruction trees
41 *
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.
49 *
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).
56 *
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 accpet 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.
64 *
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
69 * derived class code.
70 *
71 * For more information about hierarchical visitors, see:
72 *
73 *    http://c2.com/cgi/wiki?HierarchicalVisitorPattern
74 *    http://c2.com/cgi/wiki?HierarchicalVisitorDiscussion
75 */
76
77class ir_hierarchical_visitor {
78public:
79   ir_hierarchical_visitor();
80
81   /**
82    * \name Visit methods for leaf-node classes
83    */
84   /*@{*/
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
90   /**
91    * ir_dereference_variable isn't technically a leaf, but it is treated as a
92    * leaf here for a couple reasons.  By not automatically visiting the one
93    * child ir_variable node from the ir_dereference_variable, ir_variable
94    * nodes can always be handled as variable declarations.  Code that used
95    * non-hierarchical visitors had to set an "in a dereference" flag to
96    * determine how to handle an ir_variable.  By forcing the visitor to
97    * handle the ir_variable within the ir_dereference_variable visitor, this
98    * kludge can be avoided.
99    *
100    * In addition, I can envision no use for having separate enter and leave
101    * methods.  Anything that could be done in the enter and leave methods
102    * that couldn't just be done in the visit method.
103    */
104   virtual ir_visitor_status visit(class ir_dereference_variable *);
105   /*@}*/
106
107   /**
108    * \name Visit methods for internal-node classes
109    */
110   /*@{*/
111   virtual ir_visitor_status visit_enter(class ir_loop *);
112   virtual ir_visitor_status visit_leave(class ir_loop *);
113   virtual ir_visitor_status visit_enter(class ir_function_signature *);
114   virtual ir_visitor_status visit_leave(class ir_function_signature *);
115   virtual ir_visitor_status visit_enter(class ir_function *);
116   virtual ir_visitor_status visit_leave(class ir_function *);
117   virtual ir_visitor_status visit_enter(class ir_expression *);
118   virtual ir_visitor_status visit_leave(class ir_expression *);
119   virtual ir_visitor_status visit_enter(class ir_texture *);
120   virtual ir_visitor_status visit_leave(class ir_texture *);
121   virtual ir_visitor_status visit_enter(class ir_swizzle *);
122   virtual ir_visitor_status visit_leave(class ir_swizzle *);
123   virtual ir_visitor_status visit_enter(class ir_dereference_array *);
124   virtual ir_visitor_status visit_leave(class ir_dereference_array *);
125   virtual ir_visitor_status visit_enter(class ir_dereference_record *);
126   virtual ir_visitor_status visit_leave(class ir_dereference_record *);
127   virtual ir_visitor_status visit_enter(class ir_assignment *);
128   virtual ir_visitor_status visit_leave(class ir_assignment *);
129   virtual ir_visitor_status visit_enter(class ir_call *);
130   virtual ir_visitor_status visit_leave(class ir_call *);
131   virtual ir_visitor_status visit_enter(class ir_return *);
132   virtual ir_visitor_status visit_leave(class ir_return *);
133   virtual ir_visitor_status visit_enter(class ir_discard *);
134   virtual ir_visitor_status visit_leave(class ir_discard *);
135   virtual ir_visitor_status visit_enter(class ir_if *);
136   virtual ir_visitor_status visit_leave(class ir_if *);
137   /*@}*/
138
139
140   /**
141    * Utility function to process a linked list of instructions with a visitor
142    */
143   void run(struct exec_list *instructions);
144
145   /* Some visitors may need to insert new variable declarations and
146    * assignments for portions of a subtree, which means they need a
147    * pointer to the current instruction in the stream, not just their
148    * node in the tree rooted at that instruction.
149    *
150    * This is implemented by visit_list_elements -- if the visitor is
151    * not called by it, nothing good will happen.
152    */
153   class ir_instruction *base_ir;
154
155   /**
156    * Callback function that is invoked on entry to each node visited.
157    *
158    * \warning
159    * Visitor classes derived from \c ir_hierarchical_visitor \b may \b not
160    * invoke this function.  This can be used, for example, to cause the
161    * callback to be invoked on every node type execpt one.
162    */
163   void (*callback)(class ir_instruction *ir, void *data);
164
165   /**
166    * Extra data parameter passed to the per-node callback function
167    */
168   void *data;
169
170   /**
171    * Currently in the LHS of an assignment?
172    *
173    * This is set and cleared by the \c ir_assignment::accept method.
174    */
175   bool in_assignee;
176};
177
178void visit_tree(ir_instruction *ir,
179		void (*callback)(class ir_instruction *ir, void *data),
180		void *data);
181
182ir_visitor_status visit_list_elements(ir_hierarchical_visitor *v, exec_list *l,
183                                      bool statement_list = true);
184
185#endif /* IR_HIERARCHICAL_VISITOR_H */
186