140 lines
6.2 KiB
C++
140 lines
6.2 KiB
C++
/* -*- c++ -*- */
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/*
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* Copyright © 2010 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#pragma once
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#ifndef IR_HIERARCHICAL_VISITOR_H
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#define IR_HIERARCHICAL_VISITOR_H
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/**
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* Enumeration values returned by visit methods to guide processing
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*/
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enum ir_visitor_status {
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visit_continue, /**< Continue visiting as normal. */
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visit_continue_with_parent, /**< Don't visit siblings, continue w/parent. */
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visit_stop /**< Stop visiting immediately. */
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};
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/**
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* Base class of hierarchical visitors of IR instruction trees
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*
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* Hierarchical visitors differ from traditional visitors in a couple of
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* important ways. Rather than having a single \c visit method for each
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* subclass in the composite, there are three kinds of visit methods.
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* Leaf-node classes have a traditional \c visit method. Internal-node
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* classes have a \c visit_enter method, which is invoked just before
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* processing child nodes, and a \c visit_leave method which is invoked just
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* after processing child nodes.
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*
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* In addition, each visit method and the \c accept methods in the composite
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* have a return value which guides the navigation. Any of the visit methods
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* can choose to continue visiting the tree as normal (by returning \c
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* visit_continue), terminate visiting any further nodes immediately (by
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* returning \c visit_stop), or stop visiting sibling nodes (by returning \c
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* visit_continue_with_parent).
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*
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* These two changes combine to allow nagivation of children to be implemented
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* in the composite's \c accept method. The \c accept method for a leaf-node
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* class will simply call the \c visit method, as usual, and pass its return
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* value on. The \c accept method for internal-node classes will call the \c
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* visit_enter method, call the \c accpet method of each child node, and,
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* finally, call the \c visit_leave method. If any of these return a value
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* other that \c visit_continue, the correct action must be taken.
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*
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* The final benefit is that the hierarchical visitor base class need not be
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* abstract. Default implementations of every \c visit, \c visit_enter, and
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* \c visit_leave method can be provided. By default each of these methods
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* simply returns \c visit_continue. This allows a significant reduction in
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* derived class code.
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*
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* For more information about hierarchical visitors, see:
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*
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* http://c2.com/cgi/wiki?HierarchicalVisitorPattern
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* http://c2.com/cgi/wiki?HierarchicalVisitorDiscussion
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*/
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class ir_hierarchical_visitor {
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public:
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/**
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* \name Visit methods for leaf-node classes
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*/
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/*@{*/
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virtual ir_visitor_status visit(class ir_variable *);
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virtual ir_visitor_status visit(class ir_constant *);
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virtual ir_visitor_status visit(class ir_loop_jump *);
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/**
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* ir_dereference_variable isn't technically a leaf, but it is treated as a
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* leaf here for a couple reasons. By not automatically visiting the one
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* child ir_variable node from the ir_dereference_variable, ir_variable
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* nodes can always be handled as variable declarations. Code that used
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* non-hierarchical visitors had to set an "in a dereference" flag to
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* determine how to handle an ir_variable. By forcing the visitor to
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* handle the ir_variable within the ir_dereference_varaible visitor, this
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* kludge can be avoided.
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*
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* In addition, I can envision no use for having separate enter and leave
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* methods. Anything that could be done in the enter and leave methods
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* that couldn't just be done in the visit method.
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*/
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virtual ir_visitor_status visit(class ir_dereference_variable *);
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/*@}*/
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/**
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* \name Visit methods for internal-node classes
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*/
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/*@{*/
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virtual ir_visitor_status visit_enter(class ir_loop *);
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virtual ir_visitor_status visit_leave(class ir_loop *);
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virtual ir_visitor_status visit_enter(class ir_function_signature *);
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virtual ir_visitor_status visit_leave(class ir_function_signature *);
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virtual ir_visitor_status visit_enter(class ir_function *);
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virtual ir_visitor_status visit_leave(class ir_function *);
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virtual ir_visitor_status visit_enter(class ir_expression *);
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virtual ir_visitor_status visit_leave(class ir_expression *);
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virtual ir_visitor_status visit_enter(class ir_swizzle *);
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virtual ir_visitor_status visit_leave(class ir_swizzle *);
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virtual ir_visitor_status visit_enter(class ir_dereference_array *);
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virtual ir_visitor_status visit_leave(class ir_dereference_array *);
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virtual ir_visitor_status visit_enter(class ir_dereference_record *);
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virtual ir_visitor_status visit_leave(class ir_dereference_record *);
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virtual ir_visitor_status visit_enter(class ir_assignment *);
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virtual ir_visitor_status visit_leave(class ir_assignment *);
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virtual ir_visitor_status visit_enter(class ir_call *);
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virtual ir_visitor_status visit_leave(class ir_call *);
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virtual ir_visitor_status visit_enter(class ir_return *);
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virtual ir_visitor_status visit_leave(class ir_return *);
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virtual ir_visitor_status visit_enter(class ir_if *);
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virtual ir_visitor_status visit_leave(class ir_if *);
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/*@}*/
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/**
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* Utility function to process a linked list of instructions with a visitor
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*/
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void run(struct exec_list *instructions);
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};
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#endif /* IR_HIERARCHICAL_VISITOR_H */
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