rtl-iter.h revision 1.6
1/* RTL iterators 2 Copyright (C) 2014-2020 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING3. If not see 18<http://www.gnu.org/licenses/>. */ 19 20/* This structure describes the subrtxes of an rtx as follows: 21 22 - if the rtx has no subrtxes, START and COUNT are both 0. 23 24 - if all the subrtxes of an rtx are stored in a contiguous block 25 of XEXPs ("e"s), START is the index of the first XEXP and COUNT 26 is the number of them. 27 28 - otherwise START is arbitrary and COUNT is UCHAR_MAX. 29 30 rtx_all_subrtx_bounds applies to all codes. rtx_nonconst_subrtx_bounds 31 is like rtx_all_subrtx_bounds except that all constant rtxes are treated 32 as having no subrtxes. */ 33struct rtx_subrtx_bound_info { 34 unsigned char start; 35 unsigned char count; 36}; 37extern rtx_subrtx_bound_info rtx_all_subrtx_bounds[]; 38extern rtx_subrtx_bound_info rtx_nonconst_subrtx_bounds[]; 39 40/* Return true if CODE has no subrtxes. */ 41 42static inline bool 43leaf_code_p (enum rtx_code code) 44{ 45 return rtx_all_subrtx_bounds[code].count == 0; 46} 47 48/* Used to iterate over subrtxes of an rtx. T abstracts the type of 49 access. */ 50template <typename T> 51class generic_subrtx_iterator 52{ 53 static const size_t LOCAL_ELEMS = 16; 54 typedef typename T::value_type value_type; 55 typedef typename T::rtx_type rtx_type; 56 typedef typename T::rtunion_type rtunion_type; 57 58public: 59 class array_type 60 { 61 public: 62 array_type (); 63 ~array_type (); 64 value_type stack[LOCAL_ELEMS]; 65 vec <value_type, va_heap, vl_embed> *heap; 66 }; 67 generic_subrtx_iterator (array_type &, value_type, 68 const rtx_subrtx_bound_info *); 69 70 value_type operator * () const; 71 bool at_end () const; 72 void next (); 73 void skip_subrtxes (); 74 void substitute (value_type); 75 76private: 77 /* The bounds to use for iterating over subrtxes. */ 78 const rtx_subrtx_bound_info *m_bounds; 79 80 /* The storage used for the worklist. */ 81 array_type &m_array; 82 83 /* The current rtx. */ 84 value_type m_current; 85 86 /* The base of the current worklist. */ 87 value_type *m_base; 88 89 /* The number of subrtxes in M_BASE. */ 90 size_t m_end; 91 92 /* The following booleans shouldn't end up in registers or memory 93 but just direct control flow. */ 94 95 /* True if the iteration is over. */ 96 bool m_done; 97 98 /* True if we should skip the subrtxes of M_CURRENT. */ 99 bool m_skip; 100 101 /* True if M_CURRENT has been replaced with a different rtx. */ 102 bool m_substitute; 103 104 static void free_array (array_type &); 105 static size_t add_subrtxes_to_queue (array_type &, value_type *, size_t, 106 rtx_type); 107 static value_type *add_single_to_queue (array_type &, value_type *, size_t, 108 value_type); 109}; 110 111template <typename T> 112inline generic_subrtx_iterator <T>::array_type::array_type () : heap (0) {} 113 114template <typename T> 115inline generic_subrtx_iterator <T>::array_type::~array_type () 116{ 117 if (__builtin_expect (heap != 0, false)) 118 free_array (*this); 119} 120 121/* Iterate over X and its subrtxes, in arbitrary order. Use ARRAY to 122 store the worklist. We use an external array in order to avoid 123 capturing the fields of this structure when taking the address of 124 the array. Use BOUNDS to find the bounds of simple "e"-string codes. */ 125 126template <typename T> 127inline generic_subrtx_iterator <T>:: 128generic_subrtx_iterator (array_type &array, value_type x, 129 const rtx_subrtx_bound_info *bounds) 130 : m_bounds (bounds), 131 m_array (array), 132 m_current (x), 133 m_base (m_array.stack), 134 m_end (0), 135 m_done (false), 136 m_skip (false), 137 m_substitute (false) 138{ 139} 140 141/* Return the current subrtx. */ 142 143template <typename T> 144inline typename T::value_type 145generic_subrtx_iterator <T>::operator * () const 146{ 147 return m_current; 148} 149 150/* Return true if the iteration has finished. */ 151 152template <typename T> 153inline bool 154generic_subrtx_iterator <T>::at_end () const 155{ 156 return m_done; 157} 158 159/* Move on to the next subrtx. */ 160 161template <typename T> 162inline void 163generic_subrtx_iterator <T>::next () 164{ 165 if (m_substitute) 166 { 167 m_substitute = false; 168 m_skip = false; 169 return; 170 } 171 if (!m_skip) 172 { 173 /* Add the subrtxes of M_CURRENT. */ 174 rtx_type x = T::get_rtx (m_current); 175 if (__builtin_expect (x != 0, true)) 176 { 177 enum rtx_code code = GET_CODE (x); 178 ssize_t count = m_bounds[code].count; 179 if (count > 0) 180 { 181 /* Handle the simple case of a single "e" block that is known 182 to fit into the current array. */ 183 if (__builtin_expect (m_end + count <= LOCAL_ELEMS + 1, true)) 184 { 185 /* Set M_CURRENT to the first subrtx and queue the rest. */ 186 ssize_t start = m_bounds[code].start; 187 rtunion_type *src = &x->u.fld[start]; 188 if (__builtin_expect (count > 2, false)) 189 m_base[m_end++] = T::get_value (src[2].rt_rtx); 190 if (count > 1) 191 m_base[m_end++] = T::get_value (src[1].rt_rtx); 192 m_current = T::get_value (src[0].rt_rtx); 193 return; 194 } 195 /* Handle cases which aren't simple "e" sequences or where 196 the sequence might overrun M_BASE. */ 197 count = add_subrtxes_to_queue (m_array, m_base, m_end, x); 198 if (count > 0) 199 { 200 m_end += count; 201 if (m_end > LOCAL_ELEMS) 202 m_base = m_array.heap->address (); 203 m_current = m_base[--m_end]; 204 return; 205 } 206 } 207 } 208 } 209 else 210 m_skip = false; 211 if (m_end == 0) 212 m_done = true; 213 else 214 m_current = m_base[--m_end]; 215} 216 217/* Skip the subrtxes of the current rtx. */ 218 219template <typename T> 220inline void 221generic_subrtx_iterator <T>::skip_subrtxes () 222{ 223 m_skip = true; 224} 225 226/* Ignore the subrtxes of the current rtx and look at X instead. */ 227 228template <typename T> 229inline void 230generic_subrtx_iterator <T>::substitute (value_type x) 231{ 232 m_substitute = true; 233 m_current = x; 234} 235 236/* Iterators for const_rtx. */ 237struct const_rtx_accessor 238{ 239 typedef const_rtx value_type; 240 typedef const_rtx rtx_type; 241 typedef const rtunion rtunion_type; 242 static rtx_type get_rtx (value_type x) { return x; } 243 static value_type get_value (rtx_type x) { return x; } 244}; 245typedef generic_subrtx_iterator <const_rtx_accessor> subrtx_iterator; 246 247/* Iterators for non-constant rtx. */ 248struct rtx_var_accessor 249{ 250 typedef rtx value_type; 251 typedef rtx rtx_type; 252 typedef rtunion rtunion_type; 253 static rtx_type get_rtx (value_type x) { return x; } 254 static value_type get_value (rtx_type x) { return x; } 255}; 256typedef generic_subrtx_iterator <rtx_var_accessor> subrtx_var_iterator; 257 258/* Iterators for rtx *. */ 259struct rtx_ptr_accessor 260{ 261 typedef rtx *value_type; 262 typedef rtx rtx_type; 263 typedef rtunion rtunion_type; 264 static rtx_type get_rtx (value_type ptr) { return *ptr; } 265 static value_type get_value (rtx_type &x) { return &x; } 266}; 267typedef generic_subrtx_iterator <rtx_ptr_accessor> subrtx_ptr_iterator; 268 269#define ALL_BOUNDS rtx_all_subrtx_bounds 270#define NONCONST_BOUNDS rtx_nonconst_subrtx_bounds 271 272/* Use ITER to iterate over const_rtx X and its recursive subrtxes, 273 using subrtx_iterator::array ARRAY as the storage for the worklist. 274 ARRAY can be reused for multiple consecutive iterations but shouldn't 275 be shared by two concurrent iterations. TYPE is ALL if all subrtxes 276 are of interest or NONCONST if it is safe to ignore subrtxes of 277 constants. */ 278#define FOR_EACH_SUBRTX(ITER, ARRAY, X, TYPE) \ 279 for (subrtx_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \ 280 ITER.next ()) 281 282/* Like FOR_EACH_SUBRTX, but iterate over subrtxes of an rtx X. */ 283#define FOR_EACH_SUBRTX_VAR(ITER, ARRAY, X, TYPE) \ 284 for (subrtx_var_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \ 285 ITER.next ()) 286 287/* Like FOR_EACH_SUBRTX, but iterate over subrtx pointers of rtx pointer X. 288 For example, if X is &PATTERN (insn) and the pattern is a SET, iterate 289 over &PATTERN (insn), &SET_DEST (PATTERN (insn)), etc. */ 290#define FOR_EACH_SUBRTX_PTR(ITER, ARRAY, X, TYPE) \ 291 for (subrtx_ptr_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \ 292 ITER.next ()) 293