PR target/47230
[official-gcc.git] / gcc / tree-ssanames.c
blob3af80a0d236ce6ba94f59f8c11f13e7f7889f544
1 /* Generic routines for manipulating SSA_NAME expressions
2 Copyright (C) 2003-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
24 #include "tree.h"
25 #include "stor-layout.h"
26 #include "basic-block.h"
27 #include "tree-ssa-alias.h"
28 #include "internal-fn.h"
29 #include "gimple-expr.h"
30 #include "is-a.h"
31 #include "gimple.h"
32 #include "gimple-ssa.h"
33 #include "tree-phinodes.h"
34 #include "ssa-iterators.h"
35 #include "stringpool.h"
36 #include "tree-ssanames.h"
37 #include "tree-into-ssa.h"
38 #include "tree-ssa.h"
39 #include "tree-pass.h"
41 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
42 many of which may be thrown away shortly after their creation if jumps
43 were threaded through PHI nodes.
45 While our garbage collection mechanisms will handle this situation, it
46 is extremely wasteful to create nodes and throw them away, especially
47 when the nodes can be reused.
49 For PR 8361, we can significantly reduce the number of nodes allocated
50 and thus the total amount of memory allocated by managing SSA_NAMEs a
51 little. This additionally helps reduce the amount of work done by the
52 garbage collector. Similar results have been seen on a wider variety
53 of tests (such as the compiler itself).
55 Right now we maintain our free list on a per-function basis. It may
56 or may not make sense to maintain the free list for the duration of
57 a compilation unit.
59 External code should rely solely upon HIGHEST_SSA_VERSION and the
60 externally defined functions. External code should not know about
61 the details of the free list management.
63 External code should also not assume the version number on nodes is
64 monotonically increasing. We reuse the version number when we
65 reuse an SSA_NAME expression. This helps keep arrays and bitmaps
66 more compact. */
69 /* Version numbers with special meanings. We start allocating new version
70 numbers after the special ones. */
71 #define UNUSED_NAME_VERSION 0
73 unsigned int ssa_name_nodes_reused;
74 unsigned int ssa_name_nodes_created;
76 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
79 /* Initialize management of SSA_NAMEs to default SIZE. If SIZE is
80 zero use default. */
82 void
83 init_ssanames (struct function *fn, int size)
85 if (size < 50)
86 size = 50;
88 vec_alloc (SSANAMES (fn), size);
90 /* Version 0 is special, so reserve the first slot in the table. Though
91 currently unused, we may use version 0 in alias analysis as part of
92 the heuristics used to group aliases when the alias sets are too
93 large.
95 We use vec::quick_push here because we know that SSA_NAMES has at
96 least 50 elements reserved in it. */
97 SSANAMES (fn)->quick_push (NULL_TREE);
98 FREE_SSANAMES (fn) = NULL;
100 fn->gimple_df->ssa_renaming_needed = 0;
101 fn->gimple_df->rename_vops = 0;
104 /* Finalize management of SSA_NAMEs. */
106 void
107 fini_ssanames (void)
109 vec_free (SSANAMES (cfun));
110 vec_free (FREE_SSANAMES (cfun));
113 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes. */
115 void
116 ssanames_print_statistics (void)
118 fprintf (stderr, "SSA_NAME nodes allocated: %u\n", ssa_name_nodes_created);
119 fprintf (stderr, "SSA_NAME nodes reused: %u\n", ssa_name_nodes_reused);
122 /* Return an SSA_NAME node for variable VAR defined in statement STMT
123 in function FN. STMT may be an empty statement for artificial
124 references (e.g., default definitions created when a variable is
125 used without a preceding definition). */
127 tree
128 make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
130 tree t;
131 use_operand_p imm;
133 gcc_assert (TREE_CODE (var) == VAR_DECL
134 || TREE_CODE (var) == PARM_DECL
135 || TREE_CODE (var) == RESULT_DECL
136 || (TYPE_P (var) && is_gimple_reg_type (var)));
138 /* If our free list has an element, then use it. */
139 if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
141 t = FREE_SSANAMES (fn)->pop ();
142 if (GATHER_STATISTICS)
143 ssa_name_nodes_reused++;
145 /* The node was cleared out when we put it on the free list, so
146 there is no need to do so again here. */
147 gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
148 (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
150 else
152 t = make_node (SSA_NAME);
153 SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
154 vec_safe_push (SSANAMES (fn), t);
155 if (GATHER_STATISTICS)
156 ssa_name_nodes_created++;
159 if (TYPE_P (var))
161 TREE_TYPE (t) = var;
162 SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
164 else
166 TREE_TYPE (t) = TREE_TYPE (var);
167 SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
169 SSA_NAME_DEF_STMT (t) = stmt;
170 if (POINTER_TYPE_P (TREE_TYPE (t)))
171 SSA_NAME_PTR_INFO (t) = NULL;
172 else
173 SSA_NAME_RANGE_INFO (t) = NULL;
175 SSA_NAME_IN_FREE_LIST (t) = 0;
176 SSA_NAME_IS_DEFAULT_DEF (t) = 0;
177 imm = &(SSA_NAME_IMM_USE_NODE (t));
178 imm->use = NULL;
179 imm->prev = imm;
180 imm->next = imm;
181 imm->loc.ssa_name = t;
183 return t;
186 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME. */
188 void
189 set_range_info (tree name, enum value_range_type range_type,
190 const wide_int_ref &min, const wide_int_ref &max)
192 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
193 gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
194 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
195 unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
197 /* Allocate if not available. */
198 if (ri == NULL)
200 size_t size = (sizeof (range_info_def)
201 + trailing_wide_ints <3>::extra_size (precision));
202 ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
203 ri->ints.set_precision (precision);
204 SSA_NAME_RANGE_INFO (name) = ri;
205 ri->set_nonzero_bits (wi::shwi (-1, precision));
208 /* Record the range type. */
209 if (SSA_NAME_RANGE_TYPE (name) != range_type)
210 SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
212 /* Set the values. */
213 ri->set_min (min);
214 ri->set_max (max);
216 /* If it is a range, try to improve nonzero_bits from the min/max. */
217 if (range_type == VR_RANGE)
219 wide_int xorv = ri->get_min () ^ ri->get_max ();
220 if (xorv != 0)
221 xorv = wi::mask (precision - wi::clz (xorv), false, precision);
222 ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
227 /* Gets range information MIN, MAX and returns enum value_range_type
228 corresponding to tree ssa_name NAME. enum value_range_type returned
229 is used to determine if MIN and MAX are valid values. */
231 enum value_range_type
232 get_range_info (const_tree name, wide_int *min, wide_int *max)
234 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
235 gcc_assert (min && max);
236 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
238 /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
239 with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision. */
240 if (!ri || (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (name)))
241 > 2 * HOST_BITS_PER_WIDE_INT))
242 return VR_VARYING;
244 *min = ri->get_min ();
245 *max = ri->get_max ();
246 return SSA_NAME_RANGE_TYPE (name);
249 /* Change non-zero bits bitmask of NAME. */
251 void
252 set_nonzero_bits (tree name, const wide_int_ref &mask)
254 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
255 if (SSA_NAME_RANGE_INFO (name) == NULL)
256 set_range_info (name, VR_RANGE,
257 TYPE_MIN_VALUE (TREE_TYPE (name)),
258 TYPE_MAX_VALUE (TREE_TYPE (name)));
259 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
260 ri->set_nonzero_bits (mask);
263 /* Return a widest_int with potentially non-zero bits in SSA_NAME
264 NAME, or -1 if unknown. */
266 wide_int
267 get_nonzero_bits (const_tree name)
269 unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
270 if (POINTER_TYPE_P (TREE_TYPE (name)))
272 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
273 if (pi && pi->align)
274 return wi::shwi (-(HOST_WIDE_INT) pi->align
275 | (HOST_WIDE_INT) pi->misalign, precision);
276 return wi::shwi (-1, precision);
279 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
280 if (!ri)
281 return wi::shwi (-1, precision);
283 return ri->get_nonzero_bits ();
286 /* We no longer need the SSA_NAME expression VAR, release it so that
287 it may be reused.
289 Note it is assumed that no calls to make_ssa_name will be made
290 until all uses of the ssa name are released and that the only
291 use of the SSA_NAME expression is to check its SSA_NAME_VAR. All
292 other fields must be assumed clobbered. */
294 void
295 release_ssa_name_fn (struct function *fn, tree var)
297 if (!var)
298 return;
300 /* Never release the default definition for a symbol. It's a
301 special SSA name that should always exist once it's created. */
302 if (SSA_NAME_IS_DEFAULT_DEF (var))
303 return;
305 /* If VAR has been registered for SSA updating, don't remove it.
306 After update_ssa has run, the name will be released. */
307 if (name_registered_for_update_p (var))
309 release_ssa_name_after_update_ssa (var);
310 return;
313 /* release_ssa_name can be called multiple times on a single SSA_NAME.
314 However, it should only end up on our free list one time. We
315 keep a status bit in the SSA_NAME node itself to indicate it has
316 been put on the free list.
318 Note that once on the freelist you can not reference the SSA_NAME's
319 defining statement. */
320 if (! SSA_NAME_IN_FREE_LIST (var))
322 tree saved_ssa_name_var = SSA_NAME_VAR (var);
323 int saved_ssa_name_version = SSA_NAME_VERSION (var);
324 use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
326 if (MAY_HAVE_DEBUG_STMTS)
327 insert_debug_temp_for_var_def (NULL, var);
329 #ifdef ENABLE_CHECKING
330 verify_imm_links (stderr, var);
331 #endif
332 while (imm->next != imm)
333 delink_imm_use (imm->next);
335 (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
336 memset (var, 0, tree_size (var));
338 imm->prev = imm;
339 imm->next = imm;
340 imm->loc.ssa_name = var;
342 /* First put back the right tree node so that the tree checking
343 macros do not complain. */
344 TREE_SET_CODE (var, SSA_NAME);
346 /* Restore the version number. */
347 SSA_NAME_VERSION (var) = saved_ssa_name_version;
349 /* Hopefully this can go away once we have the new incremental
350 SSA updating code installed. */
351 SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
353 /* Note this SSA_NAME is now in the first list. */
354 SSA_NAME_IN_FREE_LIST (var) = 1;
356 /* And finally put it on the free list. */
357 vec_safe_push (FREE_SSANAMES (fn), var);
361 /* If the alignment of the pointer described by PI is known, return true and
362 store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
363 respectively. Otherwise return false. */
365 bool
366 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
367 unsigned int *misalignp)
369 if (pi->align)
371 *alignp = pi->align;
372 *misalignp = pi->misalign;
373 return true;
375 else
376 return false;
379 /* State that the pointer described by PI has unknown alignment. */
381 void
382 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
384 pi->align = 0;
385 pi->misalign = 0;
388 /* Store the the power-of-two byte alignment and the deviation from that
389 alignment of pointer described by PI to ALIOGN and MISALIGN
390 respectively. */
392 void
393 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
394 unsigned int misalign)
396 gcc_checking_assert (align != 0);
397 gcc_assert ((align & (align - 1)) == 0);
398 gcc_assert ((misalign & ~(align - 1)) == 0);
400 pi->align = align;
401 pi->misalign = misalign;
404 /* If pointer described by PI has known alignment, increase its known
405 misalignment by INCREMENT modulo its current alignment. */
407 void
408 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
409 unsigned int increment)
411 if (pi->align != 0)
413 pi->misalign += increment;
414 pi->misalign &= (pi->align - 1);
418 /* Return the alias information associated with pointer T. It creates a
419 new instance if none existed. */
421 struct ptr_info_def *
422 get_ptr_info (tree t)
424 struct ptr_info_def *pi;
426 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
428 pi = SSA_NAME_PTR_INFO (t);
429 if (pi == NULL)
431 pi = ggc_cleared_alloc<ptr_info_def> ();
432 pt_solution_reset (&pi->pt);
433 mark_ptr_info_alignment_unknown (pi);
434 SSA_NAME_PTR_INFO (t) = pi;
437 return pi;
441 /* Creates a new SSA name using the template NAME tobe defined by
442 statement STMT in function FN. */
444 tree
445 copy_ssa_name_fn (struct function *fn, tree name, gimple stmt)
447 tree new_name;
449 if (SSA_NAME_VAR (name))
450 new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
451 else
453 new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
454 SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
457 return new_name;
461 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
462 the SSA name NAME. */
464 void
465 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
467 struct ptr_info_def *new_ptr_info;
469 gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
470 gcc_assert (!SSA_NAME_PTR_INFO (name));
472 if (!ptr_info)
473 return;
475 new_ptr_info = ggc_alloc<ptr_info_def> ();
476 *new_ptr_info = *ptr_info;
478 SSA_NAME_PTR_INFO (name) = new_ptr_info;
481 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
482 RANGE_TYPE for use by the SSA name NAME. */
483 void
484 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
485 struct range_info_def *range_info)
487 struct range_info_def *new_range_info;
489 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
490 gcc_assert (!SSA_NAME_RANGE_INFO (name));
491 gcc_assert (!SSA_NAME_ANTI_RANGE_P (name));
493 if (!range_info)
494 return;
496 unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
497 size_t size = (sizeof (range_info_def)
498 + trailing_wide_ints <3>::extra_size (precision));
499 new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
500 memcpy (new_range_info, range_info, size);
502 gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
503 SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
504 SSA_NAME_RANGE_INFO (name) = new_range_info;
509 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
510 in function FN. */
512 tree
513 duplicate_ssa_name_fn (struct function *fn, tree name, gimple stmt)
515 tree new_name = copy_ssa_name_fn (fn, name, stmt);
516 if (POINTER_TYPE_P (TREE_TYPE (name)))
518 struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
520 if (old_ptr_info)
521 duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
523 else
525 struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
527 if (old_range_info)
528 duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
529 old_range_info);
532 return new_name;
536 /* Release all the SSA_NAMEs created by STMT. */
538 void
539 release_defs (gimple stmt)
541 tree def;
542 ssa_op_iter iter;
544 /* Make sure that we are in SSA. Otherwise, operand cache may point
545 to garbage. */
546 gcc_assert (gimple_in_ssa_p (cfun));
548 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
549 if (TREE_CODE (def) == SSA_NAME)
550 release_ssa_name (def);
554 /* Replace the symbol associated with SSA_NAME with SYM. */
556 void
557 replace_ssa_name_symbol (tree ssa_name, tree sym)
559 SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
560 TREE_TYPE (ssa_name) = TREE_TYPE (sym);
563 /* Return SSA names that are unused to GGC memory and compact the SSA
564 version namespace. This is used to keep footprint of compiler during
565 interprocedural optimization. */
567 namespace {
569 const pass_data pass_data_release_ssa_names =
571 GIMPLE_PASS, /* type */
572 "release_ssa", /* name */
573 OPTGROUP_NONE, /* optinfo_flags */
574 TV_TREE_SSA_OTHER, /* tv_id */
575 PROP_ssa, /* properties_required */
576 0, /* properties_provided */
577 0, /* properties_destroyed */
578 TODO_remove_unused_locals, /* todo_flags_start */
579 0, /* todo_flags_finish */
582 class pass_release_ssa_names : public gimple_opt_pass
584 public:
585 pass_release_ssa_names (gcc::context *ctxt)
586 : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
589 /* opt_pass methods: */
590 virtual unsigned int execute (function *);
592 }; // class pass_release_ssa_names
594 unsigned int
595 pass_release_ssa_names::execute (function *fun)
597 unsigned i, j;
598 int n = vec_safe_length (FREE_SSANAMES (fun));
600 /* Now release the freelist. */
601 vec_free (FREE_SSANAMES (fun));
603 /* And compact the SSA number space. We make sure to not change the
604 relative order of SSA versions. */
605 for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
607 tree name = ssa_name (i);
608 if (name)
610 if (i != j)
612 SSA_NAME_VERSION (name) = j;
613 (*fun->gimple_df->ssa_names)[j] = name;
615 j++;
618 fun->gimple_df->ssa_names->truncate (j);
620 statistics_counter_event (fun, "SSA names released", n);
621 statistics_counter_event (fun, "SSA name holes removed", i - j);
622 if (dump_file)
623 fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
624 n, n * 100.0 / num_ssa_names, i - j);
625 return 0;
628 } // anon namespace
630 gimple_opt_pass *
631 make_pass_release_ssa_names (gcc::context *ctxt)
633 return new pass_release_ssa_names (ctxt);