| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2019 University of Waterloo
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| 3 | //
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| 4 | // The contents of this file are covered under the licence agreement in the
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| 5 | // file "LICENCE" distributed with Cforall.
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| 6 | //
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| 7 | // Pass.impl.hpp --
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| 8 | //
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| 9 | // Author           : Thierry Delisle
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| 10 | // Created On       : Thu May 09 15::37::05 2019
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| 11 | // Last Modified By :
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| 12 | // Last Modified On :
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| 13 | // Update Count     :
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| 14 | //
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| 15 | 
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| 16 | #pragma once
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| 17 | // IWYU pragma: private, include "Pass.hpp"
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| 18 | 
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| 19 | namespace ast {
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| 20 | template<typename pass_type>
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| 21 | class Pass;
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| 22 | 
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| 23 | namespace __pass {
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| 24 |         typedef std::function<void( void * )> cleanup_func_t;
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| 25 |         typedef std::function<void( cleanup_func_t, void * )> at_cleanup_t;
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| 26 | 
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| 27 | 
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| 28 |         // boolean reference that may be null
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| 29 |         // either refers to a boolean value or is null and returns true
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| 30 |         class bool_ref {
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| 31 |         public:
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| 32 |                 bool_ref() = default;
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| 33 |                 ~bool_ref() = default;
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| 34 | 
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| 35 |                 operator bool() { return m_ref ? *m_ref : true; }
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| 36 |                 bool operator=( bool val ) { assert(m_ref); return *m_ref = val; }
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| 37 | 
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| 38 |         private:
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| 39 | 
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| 40 |                 friend class visit_children_guard;
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| 41 | 
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| 42 |                 bool * set( bool * val ) {
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| 43 |                         bool * prev = m_ref;
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| 44 |                         m_ref = val;
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| 45 |                         return prev;
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| 46 |                 }
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| 47 | 
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| 48 |                 bool * m_ref = nullptr;
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| 49 |         };
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| 50 | 
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| 51 |         // Implementation of the guard value
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| 52 |         // Created inside the visit scope
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| 53 |         class guard_value {
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| 54 |         public:
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| 55 |                 /// Push onto the cleanup
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| 56 |                 guard_value( at_cleanup_t * at_cleanup ) {
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| 57 |                         if( at_cleanup ) {
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| 58 |                                 *at_cleanup = [this]( cleanup_func_t && func, void* val ) {
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| 59 |                                         push( std::move( func ), val );
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| 60 |                                 };
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| 61 |                         }
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| 62 |                 }
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| 63 | 
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| 64 |                 ~guard_value() {
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| 65 |                         while( !cleanups.empty() ) {
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| 66 |                                 auto& cleanup = cleanups.top();
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| 67 |                                 cleanup.func( cleanup.val );
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| 68 |                                 cleanups.pop();
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| 69 |                         }
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| 70 |                 }
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| 71 | 
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| 72 |                 void push( cleanup_func_t && func, void* val ) {
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| 73 |                         cleanups.emplace( std::move(func), val );
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| 74 |                 }
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| 75 | 
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| 76 |         private:
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| 77 |                 struct cleanup_t {
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| 78 |                         cleanup_func_t func;
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| 79 |                         void * val;
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| 80 | 
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| 81 |                         cleanup_t( cleanup_func_t&& func, void * val ) : func(func), val(val) {}
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| 82 |                 };
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| 83 | 
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| 84 |                 std::stack< cleanup_t > cleanups;
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| 85 |         };
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| 86 | 
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| 87 |         // Guard structure implementation for whether or not children should be visited
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| 88 |         class visit_children_guard {
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| 89 |         public:
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| 90 | 
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| 91 |                 visit_children_guard( bool_ref * ref )
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| 92 |                         : m_val ( true )
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| 93 |                         , m_prev( ref ? ref->set( &m_val ) : nullptr )
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| 94 |                         , m_ref ( ref )
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| 95 |                 {}
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| 96 | 
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| 97 |                 ~visit_children_guard() {
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| 98 |                         if( m_ref ) {
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| 99 |                                 m_ref->set( m_prev );
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| 100 |                         }
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| 101 |                 }
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| 102 | 
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| 103 |                 operator bool() { return m_val; }
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| 104 | 
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| 105 |         private:
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| 106 |                 bool       m_val;
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| 107 |                 bool     * m_prev;
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| 108 |                 bool_ref * m_ref;
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| 109 |         };
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| 110 | 
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| 111 |         /// "Short hand" to check if this is a valid previsit function
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| 112 |         /// Mostly used to make the static_assert look (and print) prettier
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| 113 |         template<typename pass_t, typename node_t>
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| 114 |         struct is_valid_previsit {
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| 115 |                 using ret_t = decltype( ((pass_t*)nullptr)->previsit( (const node_t *)nullptr ) );
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| 116 | 
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| 117 |                 static constexpr bool value = std::is_void< ret_t >::value ||
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| 118 |                         std::is_base_of<const node_t, typename std::remove_pointer<ret_t>::type >::value;
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| 119 |         };
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| 120 | 
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| 121 |         /// Used by previsit implementation
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| 122 |         /// We need to reassign the result to 'node', unless the function
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| 123 |         /// returns void, then we just leave 'node' unchanged
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| 124 |         template<bool is_void>
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| 125 |         struct __assign;
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| 126 | 
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| 127 |         template<>
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| 128 |         struct __assign<true> {
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| 129 |                 template<typename pass_t, typename node_t>
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| 130 |                 static inline void result( pass_t & pass, const node_t * & node ) {
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| 131 |                         pass.previsit( node );
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| 132 |                 }
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| 133 |         };
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| 134 | 
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| 135 |         template<>
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| 136 |         struct __assign<false> {
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| 137 |                 template<typename pass_t, typename node_t>
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| 138 |                 static inline void result( pass_t & pass, const node_t * & node ) {
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| 139 |                         node = pass.previsit( node );
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| 140 |                         assertf(node, "Previsit must not return NULL");
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| 141 |                 }
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| 142 |         };
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| 143 | 
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| 144 |         /// Used by postvisit implementation
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| 145 |         /// We need to return the result unless the function
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| 146 |         /// returns void, then we just return the original node
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| 147 |         template<bool is_void>
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| 148 |         struct __return;
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| 149 | 
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| 150 |         template<>
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| 151 |         struct __return<true> {
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| 152 |                 template<typename pass_t, typename node_t>
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| 153 |                 static inline const node_t * result( pass_t & pass, const node_t * & node ) {
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| 154 |                         pass.postvisit( node );
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| 155 |                         return node;
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| 156 |                 }
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| 157 |         };
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| 158 | 
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| 159 |         template<>
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| 160 |         struct __return<false> {
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| 161 |                 template<typename pass_t, typename node_t>
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| 162 |                 static inline auto result( pass_t & pass, const node_t * & node ) {
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| 163 |                         return pass.postvisit( node );
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| 164 |                 }
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| 165 |         };
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| 166 | 
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| 167 |         //-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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| 168 |         // Deep magic (a.k.a template meta programming) to make the templated visitor work
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| 169 |         // Basically the goal is to make 2 previsit
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| 170 |         // 1 - Use when a pass implements a valid previsit. This uses overloading which means the any overload of
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| 171 |         //     'pass.previsit( node )' that compiles will be used for that node for that type
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| 172 |         //     This requires that this option only compile for passes that actually define an appropriate visit.
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| 173 |         //     SFINAE will make sure the compilation errors in this function don't halt the build.
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| 174 |         //     See http://en.cppreference.com/w/cpp/language/sfinae for details on SFINAE
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| 175 |         // 2 - Since the first implementation might not be specilizable, the second implementation exists and does nothing.
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| 176 |         //     This is needed only to eliminate the need for passes to specify any kind of handlers.
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| 177 |         //     The second implementation only works because it has a lower priority. This is due to the bogus last parameter.
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| 178 |         //     The second implementation takes a long while the first takes an int. Since the caller always passes an literal 0
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| 179 |         //     the first implementation takes priority in regards to overloading.
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| 180 |         //-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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| 181 |         // PreVisit : may mutate the pointer passed in if the node is mutated in the previsit call
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| 182 |         template<typename pass_t, typename node_t>
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| 183 |         static inline auto previsit( pass_t & pass, const node_t * & node, int ) -> decltype( pass.previsit( node ), void() ) {
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| 184 |                 static_assert(
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| 185 |                         is_valid_previsit<pass_t, node_t>::value,
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| 186 |                         "Previsit may not change the type of the node. It must return its paremeter or void."
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| 187 |                 );
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| 188 | 
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| 189 |                 __assign<
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| 190 |                         std::is_void<
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| 191 |                                 decltype( pass.previsit( node ) )
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| 192 |                         >::value
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| 193 |                 >::result( pass, node );
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| 194 |         }
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| 195 | 
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| 196 |         template<typename pass_t, typename node_t>
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| 197 |         static inline auto previsit( pass_t &, const node_t *, long ) {}
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| 198 | 
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| 199 |         // PostVisit : never mutates the passed pointer but may return a different node
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| 200 |         template<typename pass_t, typename node_t>
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| 201 |         static inline auto postvisit( pass_t & pass, const node_t * node, int ) ->
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| 202 |                 decltype( pass.postvisit( node ), node->accept( *(Visitor*)nullptr ) )
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| 203 |         {
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| 204 |                 return __return<
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| 205 |                         std::is_void<
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| 206 |                                 decltype( pass.postvisit( node ) )
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| 207 |                         >::value
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| 208 |                 >::result( pass, node );
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| 209 |         }
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| 210 | 
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| 211 |         template<typename pass_t, typename node_t>
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| 212 |         static inline const node_t * postvisit( pass_t &, const node_t * node, long ) { return node; }
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| 213 | 
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| 214 |         //-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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| 215 |         // Deep magic (a.k.a template meta programming) continued
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| 216 |         // To make the templated visitor be more expressive, we allow 'accessories' : classes/structs the implementation can inherit
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| 217 |         // from in order to get extra functionallity for example
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| 218 |         // class ErrorChecker : WithShortCircuiting { ... };
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| 219 |         // Pass<ErrorChecker> checker;
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| 220 |         // this would define a pass that uses the templated visitor with the additionnal feature that it has short circuiting
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| 221 |         // Note that in all cases the accessories are not required but guarantee the requirements of the feature is matched
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| 222 |         //-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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| 223 |         // For several accessories, the feature is enabled by detecting that a specific field is present
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| 224 |         // Use a macro the encapsulate the logic of detecting a particular field
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| 225 |         // The type is not strictly enforced but does match the accessory
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| 226 |         #define FIELD_PTR( name, default_type ) \
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| 227 |         template< typename pass_t > \
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| 228 |         static inline auto name( pass_t & pass, int ) -> decltype( &pass.name ) { return &pass.name; } \
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| 229 |         \
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| 230 |         template< typename pass_t > \
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| 231 |         static inline default_type * name( pass_t &, long ) { return nullptr; }
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| 232 | 
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| 233 |         // List of fields and their expected types
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| 234 |         FIELD_PTR( env, const ast::TypeSubstitution * )
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| 235 |         FIELD_PTR( stmtsToAddBefore, std::list< ast::ptr< ast::Stmt > > )
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| 236 |         FIELD_PTR( stmtsToAddAfter , std::list< ast::ptr< ast::Stmt > > )
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| 237 |         FIELD_PTR( declsToAddBefore, std::list< ast::ptr< ast::Decl > > )
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| 238 |         FIELD_PTR( declsToAddAfter , std::list< ast::ptr< ast::Decl > > )
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| 239 |         FIELD_PTR( visit_children, __pass::bool_ref )
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| 240 |         FIELD_PTR( at_cleanup, __pass::at_cleanup_t )
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| 241 |         FIELD_PTR( visitor, ast::Pass<pass_t> * const )
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| 242 | 
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| 243 |         // Remove the macro to make sure we don't clash
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| 244 |         #undef FIELD_PTR
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| 245 | 
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| 246 |         // Another feature of the templated visitor is that it calls beginScope()/endScope() for compound statement.
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| 247 |         // All passes which have such functions are assumed desire this behaviour
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| 248 |         // detect it using the same strategy
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| 249 |         namespace scope {
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| 250 |                 template<typename pass_t>
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| 251 |                 static inline auto enter( pass_t & pass, int ) -> decltype( pass.beginScope(), void() ) {
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| 252 |                         pass.beginScope();
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| 253 |                 }
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| 254 | 
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| 255 |                 template<typename pass_t>
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| 256 |                 static inline void enter( pass_t &, long ) {}
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| 257 | 
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| 258 |                 template<typename pass_t>
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| 259 |                 static inline auto leave( pass_t & pass, int ) -> decltype( pass.endScope(), void() ) {
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| 260 |                         pass.endScope();
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| 261 |                 }
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| 262 | 
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| 263 |                 template<typename pass_t>
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| 264 |                 static inline void leave( pass_t &, long ) {}
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| 265 |         };
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| 266 | 
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| 267 |         // Finally certain pass desire an up to date symbol table automatically
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| 268 |         // detect the presence of a member name `symtab` and call all the members appropriately
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| 269 |         namespace symtab {
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| 270 |                 // Some simple scoping rules
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| 271 |                 template<typename pass_t>
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| 272 |                 static inline auto enter( pass_t & pass, int ) -> decltype( pass.symtab.enterScope(), void() ) {
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| 273 |                         pass.symtab.enterScope();
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| 274 |                 }
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| 275 | 
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| 276 |                 template<typename pass_t>
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| 277 |                 static inline auto enter( pass_t &, long ) {}
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| 278 | 
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| 279 |                 template<typename pass_t>
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| 280 |                 static inline auto leave( pass_t & pass, int ) -> decltype( pass.symtab.leaveScope(), void() ) {
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| 281 |                         pass.symtab.leaveScope();
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| 282 |                 }
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| 283 | 
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| 284 |                 template<typename pass_t>
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| 285 |                 static inline auto leave( pass_t &, long ) {}
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| 286 | 
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| 287 |                 // The symbol table has 2 kind of functions mostly, 1 argument and 2 arguments
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| 288 |                 // Create macro to condense these common patterns
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| 289 |                 #define SYMTAB_FUNC1( func, type ) \
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| 290 |                 template<typename pass_t> \
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| 291 |                 static inline auto func( pass_t & pass, int, type arg ) -> decltype( pass.symtab.func( arg ), void() ) {\
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| 292 |                         pass.symtab.func( arg ); \
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| 293 |                 } \
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| 294 |                 \
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| 295 |                 template<typename pass_t> \
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| 296 |                 static inline void func( pass_t &, long, type ) {}
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| 297 | 
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| 298 |                 #define SYMTAB_FUNC2( func, type1, type2 ) \
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| 299 |                 template<typename pass_t> \
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| 300 |                 static inline auto func( pass_t & pass, int, type1 arg1, type2 arg2 ) -> decltype( pass.symtab.func( arg1, arg2 ), void () ) {\
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| 301 |                         pass.symtab.func( arg1, arg2 ); \
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| 302 |                 } \
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| 303 |                         \
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| 304 |                 template<typename pass_t> \
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| 305 |                 static inline void func( pass_t &, long, type1, type2 ) {}
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| 306 | 
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| 307 |                 SYMTAB_FUNC1( addId     , const DeclWithType *  );
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| 308 |                 SYMTAB_FUNC1( addType   , const NamedTypeDecl * );
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| 309 |                 SYMTAB_FUNC1( addStruct , const StructDecl *    );
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| 310 |                 SYMTAB_FUNC1( addEnum   , const EnumDecl *      );
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| 311 |                 SYMTAB_FUNC1( addUnion  , const UnionDecl *     );
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| 312 |                 SYMTAB_FUNC1( addTrait  , const TraitDecl *     );
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| 313 |                 SYMTAB_FUNC2( addWith   , const std::vector< ptr<Expr> > &, const Node * );
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| 314 | 
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| 315 |                 // A few extra functions have more complicated behaviour, they are hand written
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| 316 |                 template<typename pass_t>
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| 317 |                 static inline auto addStructFwd( pass_t & pass, int, const ast::StructDecl * decl ) -> decltype( pass.symtab.addStruct( decl ), void() ) {
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| 318 |                         ast::StructDecl * fwd = new ast::StructDecl( decl->location, decl->name );
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| 319 |                         fwd->params = decl->params;
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| 320 |                         pass.symtab.addStruct( fwd );
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| 321 |                 }
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| 322 | 
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| 323 |                 template<typename pass_t>
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| 324 |                 static inline void addStructFwd( pass_t &, long, const ast::StructDecl * ) {}
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| 325 | 
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| 326 |                 template<typename pass_t>
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| 327 |                 static inline auto addUnionFwd( pass_t & pass, int, const ast::UnionDecl * decl ) -> decltype( pass.symtab.addUnion( decl ), void() ) {
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| 328 |                         UnionDecl * fwd = new UnionDecl( decl->location, decl->name );
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| 329 |                         fwd->params = decl->params;
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| 330 |                         pass.symtab.addUnion( fwd );
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| 331 |                 }
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| 332 | 
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| 333 |                 template<typename pass_t>
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| 334 |                 static inline void addUnionFwd( pass_t &, long, const ast::UnionDecl * ) {}
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| 335 | 
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| 336 |                 template<typename pass_t>
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| 337 |                 static inline auto addStruct( pass_t & pass, int, const std::string & str ) -> decltype( pass.symtab.addStruct( str ), void() ) {
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| 338 |                         if ( ! pass.symtab.lookupStruct( str ) ) {
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| 339 |                                 pass.symtab.addStruct( str );
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| 340 |                         }
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| 341 |                 }
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| 342 | 
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| 343 |                 template<typename pass_t>
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| 344 |                 static inline void addStruct( pass_t &, long, const std::string & ) {}
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| 345 | 
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| 346 |                 template<typename pass_t>
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| 347 |                 static inline auto addUnion( pass_t & pass, int, const std::string & str ) -> decltype( pass.symtab.addUnion( str ), void() ) {
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| 348 |                         if ( ! pass.symtab.lookupUnion( str ) ) {
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| 349 |                                 pass.symtab.addUnion( str );
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| 350 |                         }
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| 351 |                 }
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| 352 | 
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| 353 |                 template<typename pass_t>
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| 354 |                 static inline void addUnion( pass_t &, long, const std::string & ) {}
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| 355 | 
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| 356 |                 #undef SYMTAB_FUNC1
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| 357 |                 #undef SYMTAB_FUNC2
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| 358 |         };
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| 359 | };
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| 360 | };
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