src/glsl/ir_hierarchical_visitor.h

   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  */
  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. */
  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
  77 class ir_hierarchical_visitor {
  78 public:
  79    ir_hierarchical_visitor();
  80
  81    /**
  82     * \name Visit methods for leaf-node classes
  83     */
  84    /*@{*/
  85    virtual ir_visitor_status visit(class ir_variable *);
  86    virtual ir_visitor_status visit(class ir_constant *);
  87    virtual ir_visitor_status visit(class ir_loop_jump *);
  88
  89    /**
  90     * ir_dereference_variable isn't technically a leaf, but it is treated as a
  91     * leaf here for a couple reasons.  By not automatically visiting the one
  92     * child ir_variable node from the ir_dereference_variable, ir_variable
  93     * nodes can always be handled as variable declarations.  Code that used
  94     * non-hierarchical visitors had to set an "in a dereference" flag to
  95     * determine how to handle an ir_variable.  By forcing the visitor to
  96     * handle the ir_variable within the ir_dereference_variable visitor, this
  97     * kludge can be avoided.
  98     *
  99     * In addition, I can envision no use for having separate enter and leave
 100     * methods.  Anything that could be done in the enter and leave methods
 101     * that couldn't just be done in the visit method.
 102     */
 103    virtual ir_visitor_status visit(class ir_dereference_variable *);
 104    /*@}*/
 105
 106    /**
 107     * \name Visit methods for internal-node classes
 108     */
 109    /*@{*/
 110    virtual ir_visitor_status visit_enter(class ir_loop *);
 111    virtual ir_visitor_status visit_leave(class ir_loop *);
 112    virtual ir_visitor_status visit_enter(class ir_function_signature *);
 113    virtual ir_visitor_status visit_leave(class ir_function_signature *);
 114    virtual ir_visitor_status visit_enter(class ir_function *);
 115    virtual ir_visitor_status visit_leave(class ir_function *);
 116    virtual ir_visitor_status visit_enter(class ir_expression *);
 117    virtual ir_visitor_status visit_leave(class ir_expression *);
 118    virtual ir_visitor_status visit_enter(class ir_texture *);
 119    virtual ir_visitor_status visit_leave(class ir_texture *);
 120    virtual ir_visitor_status visit_enter(class ir_swizzle *);
 121    virtual ir_visitor_status visit_leave(class ir_swizzle *);
 122    virtual ir_visitor_status visit_enter(class ir_dereference_array *);
 123    virtual ir_visitor_status visit_leave(class ir_dereference_array *);
 124    virtual ir_visitor_status visit_enter(class ir_dereference_record *);
 125    virtual ir_visitor_status visit_leave(class ir_dereference_record *);
 126    virtual ir_visitor_status visit_enter(class ir_assignment *);
 127    virtual ir_visitor_status visit_leave(class ir_assignment *);
 128    virtual ir_visitor_status visit_enter(class ir_call *);
 129    virtual ir_visitor_status visit_leave(class ir_call *);
 130    virtual ir_visitor_status visit_enter(class ir_return *);
 131    virtual ir_visitor_status visit_leave(class ir_return *);
 132    virtual ir_visitor_status visit_enter(class ir_discard *);
 133    virtual ir_visitor_status visit_leave(class ir_discard *);
 134    virtual ir_visitor_status visit_enter(class ir_if *);
 135    virtual ir_visitor_status visit_leave(class ir_if *);
 136    /*@}*/
 137
 138
 139    /**
 140     * Utility function to process a linked list of instructions with a visitor
 141     */
 142    void run(struct exec_list *instructions);
 143
 144    /* Some visitors may need to insert new variable declarations and
 145     * assignments for portions of a subtree, which means they need a
 146     * pointer to the current instruction in the stream, not just their
 147     * node in the tree rooted at that instruction.
 148     *
 149     * This is implemented by visit_list_elements -- if the visitor is
 150     * not called by it, nothing good will happen.
 151     */
 152    class ir_instruction *base_ir;
 153
 154    /**
 155     * Callback function that is invoked on entry to each node visited.
 156     *
 157     * \warning
 158     * Visitor classes derived from \c ir_hierarchical_visitor \b may \b not
 159     * invoke this function.  This can be used, for example, to cause the
 160     * callback to be invoked on every node type execpt one.
 161     */
 162    void (*callback)(class ir_instruction *ir, void *data);
 163
 164    /**
 165     * Extra data parameter passed to the per-node callback function
 166     */
 167    void *data;
 168
 169    /**
 170     * Currently in the LHS of an assignment?
 171     *
 172     * This is set and cleared by the \c ir_assignment::accept method.
 173     */
 174    bool in_assignee;
 175 };
 176
 177 void visit_tree(ir_instruction *ir,
 178                 void (*callback)(class ir_instruction *ir, void *data),
 179                 void *data);
 180
 181 ir_visitor_status visit_list_elements(ir_hierarchical_visitor *v, exec_list *l);
 182
 183 #endif /* IR_HIERARCHICAL_VISITOR_H */