gcc/tree-sra.c

   1 /* Scalar Replacement of Aggregates (SRA) converts some structure
   2    references into scalar references, exposing them to the scalar
   3    optimizers.
   4    Copyright (C) 2008-2015 Free Software Foundation, Inc.
   5    Contributed by Martin Jambor <mjambor@suse.cz>
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it under
  10 the terms of the GNU General Public License as published by the Free
  11 Software Foundation; either version 3, or (at your option) any later
  12 version.
  13
  14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 /* This file implements Scalar Reduction of Aggregates (SRA).  SRA is run
  24    twice, once in the early stages of compilation (early SRA) and once in the
  25    late stages (late SRA).  The aim of both is to turn references to scalar
  26    parts of aggregates into uses of independent scalar variables.
  27
  28    The two passes are nearly identical, the only difference is that early SRA
  29    does not scalarize unions which are used as the result in a GIMPLE_RETURN
  30    statement because together with inlining this can lead to weird type
  31    conversions.
  32
  33    Both passes operate in four stages:
  34
  35    1. The declarations that have properties which make them candidates for
  36       scalarization are identified in function find_var_candidates().  The
  37       candidates are stored in candidate_bitmap.
  38
  39    2. The function body is scanned.  In the process, declarations which are
  40       used in a manner that prevent their scalarization are removed from the
  41       candidate bitmap.  More importantly, for every access into an aggregate,
  42       an access structure (struct access) is created by create_access() and
  43       stored in a vector associated with the aggregate.  Among other
  44       information, the aggregate declaration, the offset and size of the access
  45       and its type are stored in the structure.
  46
  47       On a related note, assign_link structures are created for every assign
  48       statement between candidate aggregates and attached to the related
  49       accesses.
  50
  51    3. The vectors of accesses are analyzed.  They are first sorted according to
  52       their offset and size and then scanned for partially overlapping accesses
  53       (i.e. those which overlap but one is not entirely within another).  Such
  54       an access disqualifies the whole aggregate from being scalarized.
  55
  56       If there is no such inhibiting overlap, a representative access structure
  57       is chosen for every unique combination of offset and size.  Afterwards,
  58       the pass builds a set of trees from these structures, in which children
  59       of an access are within their parent (in terms of offset and size).
  60
  61       Then accesses  are propagated  whenever possible (i.e.  in cases  when it
  62       does not create a partially overlapping access) across assign_links from
  63       the right hand side to the left hand side.
  64
  65       Then the set of trees for each declaration is traversed again and those
  66       accesses which should be replaced by a scalar are identified.
  67
  68    4. The function is traversed again, and for every reference into an
  69       aggregate that has some component which is about to be scalarized,
  70       statements are amended and new statements are created as necessary.
  71       Finally, if a parameter got scalarized, the scalar replacements are
  72       initialized with values from respective parameter aggregates.  */
  73
  74 #include "config.h"
  75 #include "system.h"
  76 #include "coretypes.h"
  77 #include "alloc-pool.h"
  78 #include "backend.h"
  79 #include "predict.h"
  80 #include "tree.h"
  81 #include "gimple.h"
  82 #include "rtl.h"
  83 #include "ssa.h"
  84 #include "alias.h"
  85 #include "fold-const.h"
  86 #include "internal-fn.h"
  87 #include "tree-eh.h"
  88 #include "stor-layout.h"
  89 #include "gimplify.h"
  90 #include "gimple-iterator.h"
  91 #include "gimplify-me.h"
  92 #include "gimple-walk.h"
  93 #include "tree-cfg.h"
  94 #include "flags.h"
  95 #include "insn-config.h"
  96 #include "expmed.h"
  97 #include "dojump.h"
  98 #include "explow.h"
  99 #include "calls.h"
 100 #include "emit-rtl.h"
 101 #include "varasm.h"
 102 #include "stmt.h"
 103 #include "expr.h"
 104 #include "tree-dfa.h"
 105 #include "tree-ssa.h"
 106 #include "tree-pass.h"
 107 #include "cgraph.h"
 108 #include "symbol-summary.h"
 109 #include "ipa-prop.h"
 110 #include "params.h"
 111 #include "target.h"
 112 #include "dbgcnt.h"
 113 #include "tree-inline.h"
 114 #include "gimple-pretty-print.h"
 115 #include "ipa-inline.h"
 116 #include "ipa-utils.h"
 117 #include "builtins.h"
 118
 119 /* Enumeration of all aggregate reductions we can do.  */
 120 enum sra_mode { SRA_MODE_EARLY_IPA,   /* early call regularization */
 121                 SRA_MODE_EARLY_INTRA, /* early intraprocedural SRA */
 122                 SRA_MODE_INTRA };     /* late intraprocedural SRA */
 123
 124 /* Global variable describing which aggregate reduction we are performing at
 125    the moment.  */
 126 static enum sra_mode sra_mode;
 127
 128 struct assign_link;
 129
 130 /* ACCESS represents each access to an aggregate variable (as a whole or a
 131    part).  It can also represent a group of accesses that refer to exactly the
 132    same fragment of an aggregate (i.e. those that have exactly the same offset
 133    and size).  Such representatives for a single aggregate, once determined,
 134    are linked in a linked list and have the group fields set.
 135
 136    Moreover, when doing intraprocedural SRA, a tree is built from those
 137    representatives (by the means of first_child and next_sibling pointers), in
 138    which all items in a subtree are "within" the root, i.e. their offset is
 139    greater or equal to offset of the root and offset+size is smaller or equal
 140    to offset+size of the root.  Children of an access are sorted by offset.
 141
 142    Note that accesses to parts of vector and complex number types always
 143    represented by an access to the whole complex number or a vector.  It is a
 144    duty of the modifying functions to replace them appropriately.  */
 145
 146 struct access
 147 {
 148   /* Values returned by  `get_ref_base_and_extent' for each component reference
 149      If EXPR isn't a component reference  just set `BASE = EXPR', `OFFSET = 0',
 150      `SIZE = TREE_SIZE (TREE_TYPE (expr))'.  */
 151   HOST_WIDE_INT offset;
 152   HOST_WIDE_INT size;
 153   tree base;
 154
 155   /* Expression.  It is context dependent so do not use it to create new
 156      expressions to access the original aggregate.  See PR 42154 for a
 157      testcase.  */
 158   tree expr;
 159   /* Type.  */
 160   tree type;
 161
 162   /* The statement this access belongs to.  */
 163   gimple stmt;
 164
 165   /* Next group representative for this aggregate. */
 166   struct access *next_grp;
 167
 168   /* Pointer to the group representative.  Pointer to itself if the struct is
 169      the representative.  */
 170   struct access *group_representative;
 171
 172   /* If this access has any children (in terms of the definition above), this
 173      points to the first one.  */
 174   struct access *first_child;
 175
 176   /* In intraprocedural SRA, pointer to the next sibling in the access tree as
 177      described above.  In IPA-SRA this is a pointer to the next access
 178      belonging to the same group (having the same representative).  */
 179   struct access *next_sibling;
 180
 181   /* Pointers to the first and last element in the linked list of assign
 182      links.  */
 183   struct assign_link *first_link, *last_link;
 184
 185   /* Pointer to the next access in the work queue.  */
 186   struct access *next_queued;
 187
 188   /* Replacement variable for this access "region."  Never to be accessed
 189      directly, always only by the means of get_access_replacement() and only
 190      when grp_to_be_replaced flag is set.  */
 191   tree replacement_decl;
 192
 193   /* Is this particular access write access? */
 194   unsigned write : 1;
 195
 196   /* Is this access an access to a non-addressable field? */
 197   unsigned non_addressable : 1;
 198
 199   /* Is this access currently in the work queue?  */
 200   unsigned grp_queued : 1;
 201
 202   /* Does this group contain a write access?  This flag is propagated down the
 203      access tree.  */
 204   unsigned grp_write : 1;
 205
 206   /* Does this group contain a read access?  This flag is propagated down the
 207      access tree.  */
 208   unsigned grp_read : 1;
 209
 210   /* Does this group contain a read access that comes from an assignment
 211      statement?  This flag is propagated down the access tree.  */
 212   unsigned grp_assignment_read : 1;
 213
 214   /* Does this group contain a write access that comes from an assignment
 215      statement?  This flag is propagated down the access tree.  */
 216   unsigned grp_assignment_write : 1;
 217
 218   /* Does this group contain a read access through a scalar type?  This flag is
 219      not propagated in the access tree in any direction.  */
 220   unsigned grp_scalar_read : 1;
 221
 222   /* Does this group contain a write access through a scalar type?  This flag
 223      is not propagated in the access tree in any direction.  */
 224   unsigned grp_scalar_write : 1;
 225
 226   /* Is this access an artificial one created to scalarize some record
 227      entirely? */
 228   unsigned grp_total_scalarization : 1;
 229
 230   /* Other passes of the analysis use this bit to make function
 231      analyze_access_subtree create scalar replacements for this group if
 232      possible.  */
 233   unsigned grp_hint : 1;
 234
 235   /* Is the subtree rooted in this access fully covered by scalar
 236      replacements?  */
 237   unsigned grp_covered : 1;
 238
 239   /* If set to true, this access and all below it in an access tree must not be
 240      scalarized.  */
 241   unsigned grp_unscalarizable_region : 1;
 242
 243   /* Whether data have been written to parts of the aggregate covered by this
 244      access which is not to be scalarized.  This flag is propagated up in the
 245      access tree.  */
 246   unsigned grp_unscalarized_data : 1;
 247
 248   /* Does this access and/or group contain a write access through a
 249      BIT_FIELD_REF?  */
 250   unsigned grp_partial_lhs : 1;
 251
 252   /* Set when a scalar replacement should be created for this variable.  */
 253   unsigned grp_to_be_replaced : 1;
 254
 255   /* Set when we want a replacement for the sole purpose of having it in
 256      generated debug statements.  */
 257   unsigned grp_to_be_debug_replaced : 1;
 258
 259   /* Should TREE_NO_WARNING of a replacement be set?  */
 260   unsigned grp_no_warning : 1;
 261
 262   /* Is it possible that the group refers to data which might be (directly or
 263      otherwise) modified?  */
 264   unsigned grp_maybe_modified : 1;
 265
 266   /* Set when this is a representative of a pointer to scalar (i.e. by
 267      reference) parameter which we consider for turning into a plain scalar
 268      (i.e. a by value parameter).  */
 269   unsigned grp_scalar_ptr : 1;
 270
 271   /* Set when we discover that this pointer is not safe to dereference in the
 272      caller.  */
 273   unsigned grp_not_necessarilly_dereferenced : 1;
 274 };
 275
 276 typedef struct access *access_p;
 277
 278
 279 /* Alloc pool for allocating access structures.  */
 280 static object_allocator<struct access> access_pool ("SRA accesses", 16);
 281
 282 /* A structure linking lhs and rhs accesses from an aggregate assignment.  They
 283    are used to propagate subaccesses from rhs to lhs as long as they don't
 284    conflict with what is already there.  */
 285 struct assign_link
 286 {
 287   struct access *lacc, *racc;
 288   struct assign_link *next;
 289 };
 290
 291 /* Alloc pool for allocating assign link structures.  */
 292 static object_allocator<assign_link> assign_link_pool ("SRA links", 16);
 293
 294 /* Base (tree) -> Vector (vec<access_p> *) map.  */
 295 static hash_map<tree, auto_vec<access_p> > *base_access_vec;
 296
 297 /* Candidate hash table helpers.  */
 298
 299 struct uid_decl_hasher : nofree_ptr_hash <tree_node>
 300 {
 301   static inline hashval_t hash (const tree_node *);
 302   static inline bool equal (const tree_node *, const tree_node *);
 303 };
 304
 305 /* Hash a tree in a uid_decl_map.  */
 306
 307 inline hashval_t
 308 uid_decl_hasher::hash (const tree_node *item)
 309 {
 310   return item->decl_minimal.uid;
 311 }
 312
 313 /* Return true if the DECL_UID in both trees are equal.  */
 314
 315 inline bool
 316 uid_decl_hasher::equal (const tree_node *a, const tree_node *b)
 317 {
 318   return (a->decl_minimal.uid == b->decl_minimal.uid);
 319 }
 320
 321 /* Set of candidates.  */
 322 static bitmap candidate_bitmap;
 323 static hash_table<uid_decl_hasher> *candidates;
 324
 325 /* For a candidate UID return the candidates decl.  */
 326
 327 static inline tree
 328 candidate (unsigned uid)
 329 {
 330  tree_node t;
 331  t.decl_minimal.uid = uid;
 332  return candidates->find_with_hash (&t, static_cast <hashval_t> (uid));
 333 }
 334
 335 /* Bitmap of candidates which we should try to entirely scalarize away and
 336    those which cannot be (because they are and need be used as a whole).  */
 337 static bitmap should_scalarize_away_bitmap, cannot_scalarize_away_bitmap;
 338
 339 /* Obstack for creation of fancy names.  */
 340 static struct obstack name_obstack;
 341
 342 /* Head of a linked list of accesses that need to have its subaccesses
 343    propagated to their assignment counterparts. */
 344 static struct access *work_queue_head;
 345
 346 /* Number of parameters of the analyzed function when doing early ipa SRA.  */
 347 static int func_param_count;
 348
 349 /* scan_function sets the following to true if it encounters a call to
 350    __builtin_apply_args.  */
 351 static bool encountered_apply_args;
 352
 353 /* Set by scan_function when it finds a recursive call.  */
 354 static bool encountered_recursive_call;
 355
 356 /* Set by scan_function when it finds a recursive call with less actual
 357    arguments than formal parameters..  */
 358 static bool encountered_unchangable_recursive_call;
 359
 360 /* This is a table in which for each basic block and parameter there is a
 361    distance (offset + size) in that parameter which is dereferenced and
 362    accessed in that BB.  */
 363 static HOST_WIDE_INT *bb_dereferences;
 364 /* Bitmap of BBs that can cause the function to "stop" progressing by
 365    returning, throwing externally, looping infinitely or calling a function
 366    which might abort etc.. */
 367 static bitmap final_bbs;
 368
 369 /* Representative of no accesses at all. */
 370 static struct access  no_accesses_representant;
 371
 372 /* Predicate to test the special value.  */
 373
 374 static inline bool
 375 no_accesses_p (struct access *access)
 376 {
 377   return access == &no_accesses_representant;
 378 }
 379
 380 /* Dump contents of ACCESS to file F in a human friendly way.  If GRP is true,
 381    representative fields are dumped, otherwise those which only describe the
 382    individual access are.  */
 383
 384 static struct
 385 {
 386   /* Number of processed aggregates is readily available in
 387      analyze_all_variable_accesses and so is not stored here.  */
 388
 389   /* Number of created scalar replacements.  */
 390   int replacements;
 391
 392   /* Number of times sra_modify_expr or sra_modify_assign themselves changed an
 393      expression.  */
 394   int exprs;
 395
 396   /* Number of statements created by generate_subtree_copies.  */
 397   int subtree_copies;
 398
 399   /* Number of statements created by load_assign_lhs_subreplacements.  */
 400   int subreplacements;
 401
 402   /* Number of times sra_modify_assign has deleted a statement.  */
 403   int deleted;
 404
 405   /* Number of times sra_modify_assign has to deal with subaccesses of LHS and
 406      RHS reparately due to type conversions or nonexistent matching
 407      references.  */
 408   int separate_lhs_rhs_handling;
 409
 410   /* Number of parameters that were removed because they were unused.  */
 411   int deleted_unused_parameters;
 412
 413   /* Number of scalars passed as parameters by reference that have been
 414      converted to be passed by value.  */
 415   int scalar_by_ref_to_by_val;
 416
 417   /* Number of aggregate parameters that were replaced by one or more of their
 418      components.  */
 419   int aggregate_params_reduced;
 420
 421   /* Numbber of components created when splitting aggregate parameters.  */
 422   int param_reductions_created;
 423 } sra_stats;
 424
 425 static void
 426 dump_access (FILE *f, struct access *access, bool grp)
 427 {
 428   fprintf (f, "access { ");
 429   fprintf (f, "base = (%d)'", DECL_UID (access->base));
 430   print_generic_expr (f, access->base, 0);
 431   fprintf (f, "', offset = " HOST_WIDE_INT_PRINT_DEC, access->offset);
 432   fprintf (f, ", size = " HOST_WIDE_INT_PRINT_DEC, access->size);
 433   fprintf (f, ", expr = ");
 434   print_generic_expr (f, access->expr, 0);
 435   fprintf (f, ", type = ");
 436   print_generic_expr (f, access->type, 0);
 437   if (grp)
 438     fprintf (f, ", grp_read = %d, grp_write = %d, grp_assignment_read = %d, "
 439              "grp_assignment_write = %d, grp_scalar_read = %d, "
 440              "grp_scalar_write = %d, grp_total_scalarization = %d, "
 441              "grp_hint = %d, grp_covered = %d, "
 442              "grp_unscalarizable_region = %d, grp_unscalarized_data = %d, "
 443              "grp_partial_lhs = %d, grp_to_be_replaced = %d, "
 444              "grp_to_be_debug_replaced = %d, grp_maybe_modified = %d, "
 445              "grp_not_necessarilly_dereferenced = %d\n",
 446              access->grp_read, access->grp_write, access->grp_assignment_read,
 447              access->grp_assignment_write, access->grp_scalar_read,
 448              access->grp_scalar_write, access->grp_total_scalarization,
 449              access->grp_hint, access->grp_covered,
 450              access->grp_unscalarizable_region, access->grp_unscalarized_data,
 451              access->grp_partial_lhs, access->grp_to_be_replaced,
 452              access->grp_to_be_debug_replaced, access->grp_maybe_modified,
 453              access->grp_not_necessarilly_dereferenced);
 454   else
 455     fprintf (f, ", write = %d, grp_total_scalarization = %d, "
 456              "grp_partial_lhs = %d\n",
 457              access->write, access->grp_total_scalarization,
 458              access->grp_partial_lhs);
 459 }
 460
 461 /* Dump a subtree rooted in ACCESS to file F, indent by LEVEL.  */
 462
 463 static void
 464 dump_access_tree_1 (FILE *f, struct access *access, int level)
 465 {
 466   do
 467     {
 468       int i;
 469
 470       for (i = 0; i < level; i++)
 471         fputs ("* ", dump_file);
 472
 473       dump_access (f, access, true);
 474
 475       if (access->first_child)
 476         dump_access_tree_1 (f, access->first_child, level + 1);
 477
 478       access = access->next_sibling;
 479     }
 480   while (access);
 481 }
 482
 483 /* Dump all access trees for a variable, given the pointer to the first root in
 484    ACCESS.  */
 485
 486 static void
 487 dump_access_tree (FILE *f, struct access *access)
 488 {
 489   for (; access; access = access->next_grp)
 490     dump_access_tree_1 (f, access, 0);
 491 }
 492
 493 /* Return true iff ACC is non-NULL and has subaccesses.  */
 494
 495 static inline bool
 496 access_has_children_p (struct access *acc)
 497 {
 498   return acc && acc->first_child;
 499 }
 500
 501 /* Return true iff ACC is (partly) covered by at least one replacement.  */
 502
 503 static bool
 504 access_has_replacements_p (struct access *acc)
 505 {
 506   struct access *child;
 507   if (acc->grp_to_be_replaced)
 508     return true;
 509   for (child = acc->first_child; child; child = child->next_sibling)
 510     if (access_has_replacements_p (child))
 511       return true;
 512   return false;
 513 }
 514
 515 /* Return a vector of pointers to accesses for the variable given in BASE or
 516    NULL if there is none.  */
 517
 518 static vec<access_p> *
 519 get_base_access_vector (tree base)
 520 {
 521   return base_access_vec->get (base);
 522 }
 523
 524 /* Find an access with required OFFSET and SIZE in a subtree of accesses rooted
 525    in ACCESS.  Return NULL if it cannot be found.  */
 526
 527 static struct access *
 528 find_access_in_subtree (struct access *access, HOST_WIDE_INT offset,
 529                         HOST_WIDE_INT size)
 530 {
 531   while (access && (access->offset != offset || access->size != size))
 532     {
 533       struct access *child = access->first_child;
 534
 535       while (child && (child->offset + child->size <= offset))
 536         child = child->next_sibling;
 537       access = child;
 538     }
 539
 540   return access;
 541 }
 542
 543 /* Return the first group representative for DECL or NULL if none exists.  */
 544
 545 static struct access *
 546 get_first_repr_for_decl (tree base)
 547 {
 548   vec<access_p> *access_vec;
 549
 550   access_vec = get_base_access_vector (base);
 551   if (!access_vec)
 552     return NULL;
 553
 554   return (*access_vec)[0];
 555 }
 556
 557 /* Find an access representative for the variable BASE and given OFFSET and
 558    SIZE.  Requires that access trees have already been built.  Return NULL if
 559    it cannot be found.  */
 560
 561 static struct access *
 562 get_var_base_offset_size_access (tree base, HOST_WIDE_INT offset,
 563                                  HOST_WIDE_INT size)
 564 {
 565   struct access *access;
 566
 567   access = get_first_repr_for_decl (base);
 568   while (access && (access->offset + access->size <= offset))
 569     access = access->next_grp;
 570   if (!access)
 571     return NULL;
 572
 573   return find_access_in_subtree (access, offset, size);
 574 }
 575
 576 /* Add LINK to the linked list of assign links of RACC.  */
 577 static void
 578 add_link_to_rhs (struct access *racc, struct assign_link *link)
 579 {
 580   gcc_assert (link->racc == racc);
 581
 582   if (!racc->first_link)
 583     {
 584       gcc_assert (!racc->last_link);
 585       racc->first_link = link;
 586     }
 587   else
 588     racc->last_link->next = link;
 589
 590   racc->last_link = link;
 591   link->next = NULL;
 592 }
 593
 594 /* Move all link structures in their linked list in OLD_RACC to the linked list
 595    in NEW_RACC.  */
 596 static void
 597 relink_to_new_repr (struct access *new_racc, struct access *old_racc)
 598 {
 599   if (!old_racc->first_link)
 600     {
 601       gcc_assert (!old_racc->last_link);
 602       return;
 603     }
 604
 605   if (new_racc->first_link)
 606     {
 607       gcc_assert (!new_racc->last_link->next);
 608       gcc_assert (!old_racc->last_link || !old_racc->last_link->next);
 609
 610       new_racc->last_link->next = old_racc->first_link;
 611       new_racc->last_link = old_racc->last_link;
 612     }
 613   else
 614     {
 615       gcc_assert (!new_racc->last_link);
 616
 617       new_racc->first_link = old_racc->first_link;
 618       new_racc->last_link = old_racc->last_link;
 619     }
 620   old_racc->first_link = old_racc->last_link = NULL;
 621 }
 622
 623 /* Add ACCESS to the work queue (which is actually a stack).  */
 624
 625 static void
 626 add_access_to_work_queue (struct access *access)
 627 {
 628   if (!access->grp_queued)
 629     {
 630       gcc_assert (!access->next_queued);
 631       access->next_queued = work_queue_head;
 632       access->grp_queued = 1;
 633       work_queue_head = access;
 634     }
 635 }
 636
 637 /* Pop an access from the work queue, and return it, assuming there is one.  */
 638
 639 static struct access *
 640 pop_access_from_work_queue (void)
 641 {
 642   struct access *access = work_queue_head;
 643
 644   work_queue_head = access->next_queued;
 645   access->next_queued = NULL;
 646   access->grp_queued = 0;
 647   return access;
 648 }
 649
 650
 651 /* Allocate necessary structures.  */
 652
 653 static void
 654 sra_initialize (void)
 655 {
 656   candidate_bitmap = BITMAP_ALLOC (NULL);
 657   candidates = new hash_table<uid_decl_hasher>
 658     (vec_safe_length (cfun->local_decls) / 2);
 659   should_scalarize_away_bitmap = BITMAP_ALLOC (NULL);
 660   cannot_scalarize_away_bitmap = BITMAP_ALLOC (NULL);
 661   gcc_obstack_init (&name_obstack);
 662   base_access_vec = new hash_map<tree, auto_vec<access_p> >;
 663   memset (&sra_stats, 0, sizeof (sra_stats));
 664   encountered_apply_args = false;
 665   encountered_recursive_call = false;
 666   encountered_unchangable_recursive_call = false;
 667 }
 668
 669 /* Deallocate all general structures.  */
 670
 671 static void
 672 sra_deinitialize (void)
 673 {
 674   BITMAP_FREE (candidate_bitmap);
 675   delete candidates;
 676   candidates = NULL;
 677   BITMAP_FREE (should_scalarize_away_bitmap);
 678   BITMAP_FREE (cannot_scalarize_away_bitmap);
 679   access_pool.release ();
 680   assign_link_pool.release ();
 681   obstack_free (&name_obstack, NULL);
 682
 683   delete base_access_vec;
 684 }
 685
 686 /* Remove DECL from candidates for SRA and write REASON to the dump file if
 687    there is one.  */
 688 static void
 689 disqualify_candidate (tree decl, const char *reason)
 690 {
 691   if (bitmap_clear_bit (candidate_bitmap, DECL_UID (decl)))
 692     candidates->remove_elt_with_hash (decl, DECL_UID (decl));
 693
 694   if (dump_file && (dump_flags & TDF_DETAILS))
 695     {
 696       fprintf (dump_file, "! Disqualifying ");
 697       print_generic_expr (dump_file, decl, 0);
 698       fprintf (dump_file, " - %s\n", reason);
 699     }
 700 }
 701
 702 /* Return true iff the type contains a field or an element which does not allow
 703    scalarization.  */
 704
 705 static bool
 706 type_internals_preclude_sra_p (tree type, const char **msg)
 707 {
 708   tree fld;
 709   tree et;
 710
 711   switch (TREE_CODE (type))
 712     {
 713     case RECORD_TYPE:
 714     case UNION_TYPE:
 715     case QUAL_UNION_TYPE:
 716       for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
 717         if (TREE_CODE (fld) == FIELD_DECL)
 718           {
 719             tree ft = TREE_TYPE (fld);
 720
 721             if (TREE_THIS_VOLATILE (fld))
 722               {
 723                 *msg = "volatile structure field";
 724                 return true;
 725               }
 726             if (!DECL_FIELD_OFFSET (fld))
 727               {
 728                 *msg = "no structure field offset";
 729                 return true;
 730               }
 731             if (!DECL_SIZE (fld))
 732               {
 733                 *msg = "zero structure field size";
 734                 return true;
 735               }
 736             if (!tree_fits_uhwi_p (DECL_FIELD_OFFSET (fld)))
 737               {
 738                 *msg = "structure field offset not fixed";
 739                 return true;
 740               }
 741             if (!tree_fits_uhwi_p (DECL_SIZE (fld)))
 742               {
 743                 *msg = "structure field size not fixed";
 744                 return true;
 745               }
 746             if (!tree_fits_shwi_p (bit_position (fld)))
 747               {
 748                 *msg = "structure field size too big";
 749                 return true;
 750               }
 751             if (AGGREGATE_TYPE_P (ft)
 752                     && int_bit_position (fld) % BITS_PER_UNIT != 0)
 753               {
 754                 *msg = "structure field is bit field";
 755                 return true;
 756               }
 757
 758             if (AGGREGATE_TYPE_P (ft) && type_internals_preclude_sra_p (ft, msg))
 759               return true;
 760           }
 761
 762       return false;
 763
 764     case ARRAY_TYPE:
 765       et = TREE_TYPE (type);
 766
 767       if (TYPE_VOLATILE (et))
 768         {
 769           *msg = "element type is volatile";
 770           return true;
 771         }
 772
 773       if (AGGREGATE_TYPE_P (et) && type_internals_preclude_sra_p (et, msg))
 774         return true;
 775
 776       return false;
 777
 778     default:
 779       return false;
 780     }
 781 }
 782
 783 /* If T is an SSA_NAME, return NULL if it is not a default def or return its
 784    base variable if it is.  Return T if it is not an SSA_NAME.  */
 785
 786 static tree
 787 get_ssa_base_param (tree t)
 788 {
 789   if (TREE_CODE (t) == SSA_NAME)
 790     {
 791       if (SSA_NAME_IS_DEFAULT_DEF (t))
 792         return SSA_NAME_VAR (t);
 793       else
 794         return NULL_TREE;
 795     }
 796   return t;
 797 }
 798
 799 /* Mark a dereference of BASE of distance DIST in a basic block tht STMT
 800    belongs to, unless the BB has already been marked as a potentially
 801    final.  */
 802
 803 static void
 804 mark_parm_dereference (tree base, HOST_WIDE_INT dist, gimple stmt)
 805 {
 806   basic_block bb = gimple_bb (stmt);
 807   int idx, parm_index = 0;
 808   tree parm;
 809
 810   if (bitmap_bit_p (final_bbs, bb->index))
 811     return;
 812
 813   for (parm = DECL_ARGUMENTS (current_function_decl);
 814        parm && parm != base;
 815        parm = DECL_CHAIN (parm))
 816     parm_index++;
 817
 818   gcc_assert (parm_index < func_param_count);
 819
 820   idx = bb->index * func_param_count + parm_index;
 821   if (bb_dereferences[idx] < dist)
 822     bb_dereferences[idx] = dist;
 823 }
 824
 825 /* Allocate an access structure for BASE, OFFSET and SIZE, clear it, fill in
 826    the three fields.  Also add it to the vector of accesses corresponding to
 827    the base.  Finally, return the new access.  */
 828
 829 static struct access *
 830 create_access_1 (tree base, HOST_WIDE_INT offset, HOST_WIDE_INT size)
 831 {
 832   struct access *access = access_pool.allocate ();
 833
 834   memset (access, 0, sizeof (struct access));
 835   access->base = base;
 836   access->offset = offset;
 837   access->size = size;
 838
 839   base_access_vec->get_or_insert (base).safe_push (access);
 840
 841   return access;
 842 }
 843
 844 /* Create and insert access for EXPR. Return created access, or NULL if it is
 845    not possible.  */
 846
 847 static struct access *
 848 create_access (tree expr, gimple stmt, bool write)
 849 {
 850   struct access *access;
 851   HOST_WIDE_INT offset, size, max_size;
 852   tree base = expr;
 853   bool ptr, unscalarizable_region = false;
 854
 855   base = get_ref_base_and_extent (expr, &offset, &size, &max_size);
 856
 857   if (sra_mode == SRA_MODE_EARLY_IPA
 858       && TREE_CODE (base) == MEM_REF)
 859     {
 860       base = get_ssa_base_param (TREE_OPERAND (base, 0));
 861       if (!base)
 862         return NULL;
 863       ptr = true;
 864     }
 865   else
 866     ptr = false;
 867
 868   if (!DECL_P (base) || !bitmap_bit_p (candidate_bitmap, DECL_UID (base)))
 869     return NULL;
 870
 871   if (sra_mode == SRA_MODE_EARLY_IPA)
 872     {
 873       if (size < 0 || size != max_size)
 874         {
 875           disqualify_candidate (base, "Encountered a variable sized access.");
 876           return NULL;
 877         }
 878       if (TREE_CODE (expr) == COMPONENT_REF
 879           && DECL_BIT_FIELD (TREE_OPERAND (expr, 1)))
 880         {
 881           disqualify_candidate (base, "Encountered a bit-field access.");
 882           return NULL;
 883         }
 884       gcc_checking_assert ((offset % BITS_PER_UNIT) == 0);
 885
 886       if (ptr)
 887         mark_parm_dereference (base, offset + size, stmt);
 888     }
 889   else
 890     {
 891       if (size != max_size)
 892         {
 893           size = max_size;
 894           unscalarizable_region = true;
 895         }
 896       if (size < 0)
 897         {
 898           disqualify_candidate (base, "Encountered an unconstrained access.");
 899           return NULL;
 900         }
 901     }
 902
 903   access = create_access_1 (base, offset, size);
 904   access->expr = expr;
 905   access->type = TREE_TYPE (expr);
 906   access->write = write;
 907   access->grp_unscalarizable_region = unscalarizable_region;
 908   access->stmt = stmt;
 909
 910   if (TREE_CODE (expr) == COMPONENT_REF
 911       && DECL_NONADDRESSABLE_P (TREE_OPERAND (expr, 1)))
 912     access->non_addressable = 1;
 913
 914   return access;
 915 }
 916
 917
 918 /* Return true iff TYPE is a RECORD_TYPE with fields that are either of gimple
 919    register types or (recursively) records with only these two kinds of fields.
 920    It also returns false if any of these records contains a bit-field.  */
 921
 922 static bool
 923 type_consists_of_records_p (tree type)
 924 {
 925   tree fld;
 926
 927   if (TREE_CODE (type) != RECORD_TYPE)
 928     return false;
 929
 930   for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
 931     if (TREE_CODE (fld) == FIELD_DECL)
 932       {
 933         tree ft = TREE_TYPE (fld);
 934
 935         if (DECL_BIT_FIELD (fld))
 936           return false;
 937
 938         if (!is_gimple_reg_type (ft)
 939             && !type_consists_of_records_p (ft))
 940           return false;
 941       }
 942
 943   return true;
 944 }
 945
 946 /* Create total_scalarization accesses for all scalar type fields in DECL that
 947    must be of a RECORD_TYPE conforming to type_consists_of_records_p.  BASE
 948    must be the top-most VAR_DECL representing the variable, OFFSET must be the
 949    offset of DECL within BASE.  REF must be the memory reference expression for
 950    the given decl.  */
 951
 952 static void
 953 completely_scalarize_record (tree base, tree decl, HOST_WIDE_INT offset,
 954                              tree ref)
 955 {
 956   tree fld, decl_type = TREE_TYPE (decl);
 957
 958   for (fld = TYPE_FIELDS (decl_type); fld; fld = DECL_CHAIN (fld))
 959     if (TREE_CODE (fld) == FIELD_DECL)
 960       {
 961         HOST_WIDE_INT pos = offset + int_bit_position (fld);
 962         tree ft = TREE_TYPE (fld);
 963         tree nref = build3 (COMPONENT_REF, TREE_TYPE (fld), ref, fld,
 964                             NULL_TREE);
 965
 966         if (is_gimple_reg_type (ft))
 967           {
 968             struct access *access;
 969             HOST_WIDE_INT size;
 970
 971             size = tree_to_uhwi (DECL_SIZE (fld));
 972             access = create_access_1 (base, pos, size);
 973             access->expr = nref;
 974             access->type = ft;
 975             access->grp_total_scalarization = 1;
 976             /* Accesses for intraprocedural SRA can have their stmt NULL.  */
 977           }
 978         else
 979           completely_scalarize_record (base, fld, pos, nref);
 980       }
 981 }
 982
 983 /* Create total_scalarization accesses for all scalar type fields in VAR and
 984    for VAR as a whole.  VAR must be of a RECORD_TYPE conforming to
 985    type_consists_of_records_p.   */
 986
 987 static void
 988 completely_scalarize_var (tree var)
 989 {
 990   HOST_WIDE_INT size = tree_to_uhwi (DECL_SIZE (var));
 991   struct access *access;
 992
 993   access = create_access_1 (var, 0, size);
 994   access->expr = var;
 995   access->type = TREE_TYPE (var);
 996   access->grp_total_scalarization = 1;
 997
 998   completely_scalarize_record (var, var, 0, var);
 999 }
1000
1001 /* Return true if REF has an VIEW_CONVERT_EXPR somewhere in it.  */
1002
1003 static inline bool
1004 contains_view_convert_expr_p (const_tree ref)
1005 {
1006   while (handled_component_p (ref))
1007     {
1008       if (TREE_CODE (ref) == VIEW_CONVERT_EXPR)
1009         return true;
1010       ref = TREE_OPERAND (ref, 0);
1011     }
1012
1013   return false;
1014 }
1015
1016 /* Search the given tree for a declaration by skipping handled components and
1017    exclude it from the candidates.  */
1018
1019 static void
1020 disqualify_base_of_expr (tree t, const char *reason)
1021 {
1022   t = get_base_address (t);
1023   if (sra_mode == SRA_MODE_EARLY_IPA
1024       && TREE_CODE (t) == MEM_REF)
1025     t = get_ssa_base_param (TREE_OPERAND (t, 0));
1026
1027   if (t && DECL_P (t))
1028     disqualify_candidate (t, reason);
1029 }
1030
1031 /* Scan expression EXPR and create access structures for all accesses to
1032    candidates for scalarization.  Return the created access or NULL if none is
1033    created.  */
1034
1035 static struct access *
1036 build_access_from_expr_1 (tree expr, gimple stmt, bool write)
1037 {
1038   struct access *ret = NULL;
1039   bool partial_ref;
1040
1041   if (TREE_CODE (expr) == BIT_FIELD_REF
1042       || TREE_CODE (expr) == IMAGPART_EXPR
1043       || TREE_CODE (expr) == REALPART_EXPR)
1044     {
1045       expr = TREE_OPERAND (expr, 0);
1046       partial_ref = true;
1047     }
1048   else
1049     partial_ref = false;
1050
1051   /* We need to dive through V_C_Es in order to get the size of its parameter
1052      and not the result type.  Ada produces such statements.  We are also
1053      capable of handling the topmost V_C_E but not any of those buried in other
1054      handled components.  */
1055   if (TREE_CODE (expr) == VIEW_CONVERT_EXPR)
1056     expr = TREE_OPERAND (expr, 0);
1057
1058   if (contains_view_convert_expr_p (expr))
1059     {
1060       disqualify_base_of_expr (expr, "V_C_E under a different handled "
1061                                "component.");
1062       return NULL;
1063     }
1064   if (TREE_THIS_VOLATILE (expr))
1065     {
1066       disqualify_base_of_expr (expr, "part of a volatile reference.");
1067       return NULL;
1068     }
1069
1070   switch (TREE_CODE (expr))
1071     {
1072     case MEM_REF:
1073       if (TREE_CODE (TREE_OPERAND (expr, 0)) != ADDR_EXPR
1074           && sra_mode != SRA_MODE_EARLY_IPA)
1075         return NULL;
1076       /* fall through */
1077     case VAR_DECL:
1078     case PARM_DECL:
1079     case RESULT_DECL:
1080     case COMPONENT_REF:
1081     case ARRAY_REF:
1082     case ARRAY_RANGE_REF:
1083       ret = create_access (expr, stmt, write);
1084       break;
1085
1086     default:
1087       break;
1088     }
1089
1090   if (write && partial_ref && ret)
1091     ret->grp_partial_lhs = 1;
1092
1093   return ret;
1094 }
1095
1096 /* Scan expression EXPR and create access structures for all accesses to
1097    candidates for scalarization.  Return true if any access has been inserted.
1098    STMT must be the statement from which the expression is taken, WRITE must be
1099    true if the expression is a store and false otherwise. */
1100
1101 static bool
1102 build_access_from_expr (tree expr, gimple stmt, bool write)
1103 {
1104   struct access *access;
1105
1106   access = build_access_from_expr_1 (expr, stmt, write);
1107   if (access)
1108     {
1109       /* This means the aggregate is accesses as a whole in a way other than an
1110          assign statement and thus cannot be removed even if we had a scalar
1111          replacement for everything.  */
1112       if (cannot_scalarize_away_bitmap)
1113         bitmap_set_bit (cannot_scalarize_away_bitmap, DECL_UID (access->base));
1114       return true;
1115     }
1116   return false;
1117 }
1118
1119 /* Return the single non-EH successor edge of BB or NULL if there is none or
1120    more than one.  */
1121
1122 static edge
1123 single_non_eh_succ (basic_block bb)
1124 {
1125   edge e, res = NULL;
1126   edge_iterator ei;
1127
1128   FOR_EACH_EDGE (e, ei, bb->succs)
1129     if (!(e->flags & EDGE_EH))
1130       {
1131         if (res)
1132           return NULL;
1133         res = e;
1134       }
1135
1136   return res;
1137 }
1138
1139 /* Disqualify LHS and RHS for scalarization if STMT has to terminate its BB and
1140    there is no alternative spot where to put statements SRA might need to
1141    generate after it.  The spot we are looking for is an edge leading to a
1142    single non-EH successor, if it exists and is indeed single.  RHS may be
1143    NULL, in that case ignore it.  */
1144
1145 static bool
1146 disqualify_if_bad_bb_terminating_stmt (gimple stmt, tree lhs, tree rhs)
1147 {
1148   if ((sra_mode == SRA_MODE_EARLY_INTRA || sra_mode == SRA_MODE_INTRA)
1149       && stmt_ends_bb_p (stmt))
1150     {
1151       if (single_non_eh_succ (gimple_bb (stmt)))
1152         return false;
1153
1154       disqualify_base_of_expr (lhs, "LHS of a throwing stmt.");
1155       if (rhs)
1156         disqualify_base_of_expr (rhs, "RHS of a throwing stmt.");
1157       return true;
1158     }
1159   return false;
1160 }
1161
1162 /* Scan expressions occurring in STMT, create access structures for all accesses
1163    to candidates for scalarization and remove those candidates which occur in
1164    statements or expressions that prevent them from being split apart.  Return
1165    true if any access has been inserted.  */
1166
1167 static bool
1168 build_accesses_from_assign (gimple stmt)
1169 {
1170   tree lhs, rhs;
1171   struct access *lacc, *racc;
1172
1173   if (!gimple_assign_single_p (stmt)
1174       /* Scope clobbers don't influence scalarization.  */
1175       || gimple_clobber_p (stmt))
1176     return false;
1177
1178   lhs = gimple_assign_lhs (stmt);
1179   rhs = gimple_assign_rhs1 (stmt);
1180
1181   if (disqualify_if_bad_bb_terminating_stmt (stmt, lhs, rhs))
1182     return false;
1183
1184   racc = build_access_from_expr_1 (rhs, stmt, false);
1185   lacc = build_access_from_expr_1 (lhs, stmt, true);
1186
1187   if (lacc)
1188     lacc->grp_assignment_write = 1;
1189
1190   if (racc)
1191     {
1192       racc->grp_assignment_read = 1;
1193       if (should_scalarize_away_bitmap && !gimple_has_volatile_ops (stmt)
1194           && !is_gimple_reg_type (racc->type))
1195         bitmap_set_bit (should_scalarize_away_bitmap, DECL_UID (racc->base));
1196     }
1197
1198   if (lacc && racc
1199       && (sra_mode == SRA_MODE_EARLY_INTRA || sra_mode == SRA_MODE_INTRA)
1200       && !lacc->grp_unscalarizable_region
1201       && !racc->grp_unscalarizable_region
1202       && AGGREGATE_TYPE_P (TREE_TYPE (lhs))
1203       && lacc->size == racc->size
1204       && useless_type_conversion_p (lacc->type, racc->type))
1205     {
1206       struct assign_link *link;
1207
1208       link = assign_link_pool.allocate ();
1209       memset (link, 0, sizeof (struct assign_link));
1210
1211       link->lacc = lacc;
1212       link->racc = racc;
1213
1214       add_link_to_rhs (racc, link);
1215     }
1216
1217   return lacc || racc;
1218 }
1219
1220 /* Callback of walk_stmt_load_store_addr_ops visit_addr used to determine
1221    GIMPLE_ASM operands with memory constrains which cannot be scalarized.  */
1222
1223 static bool
1224 asm_visit_addr (gimple, tree op, tree, void *)
1225 {
1226   op = get_base_address (op);
1227   if (op
1228       && DECL_P (op))
1229     disqualify_candidate (op, "Non-scalarizable GIMPLE_ASM operand.");
1230
1231   return false;
1232 }
1233
1234 /* Return true iff callsite CALL has at least as many actual arguments as there
1235    are formal parameters of the function currently processed by IPA-SRA and
1236    that their types match.  */
1237
1238 static inline bool
1239 callsite_arguments_match_p (gimple call)
1240 {
1241   if (gimple_call_num_args (call) < (unsigned) func_param_count)
1242     return false;
1243
1244   tree parm;
1245   int i;
1246   for (parm = DECL_ARGUMENTS (current_function_decl), i = 0;
1247        parm;
1248        parm = DECL_CHAIN (parm), i++)
1249     {
1250       tree arg = gimple_call_arg (call, i);
1251       if (!useless_type_conversion_p (TREE_TYPE (parm), TREE_TYPE (arg)))
1252         return false;
1253     }
1254   return true;
1255 }
1256
1257 /* Scan function and look for interesting expressions and create access
1258    structures for them.  Return true iff any access is created.  */
1259
1260 static bool
1261 scan_function (void)
1262 {
1263   basic_block bb;
1264   bool ret = false;
1265
1266   FOR_EACH_BB_FN (bb, cfun)
1267     {
1268       gimple_stmt_iterator gsi;
1269       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1270         {
1271           gimple stmt = gsi_stmt (gsi);
1272           tree t;
1273           unsigned i;
1274
1275           if (final_bbs && stmt_can_throw_external (stmt))
1276             bitmap_set_bit (final_bbs, bb->index);
1277           switch (gimple_code (stmt))
1278             {
1279             case GIMPLE_RETURN:
1280               t = gimple_return_retval (as_a <greturn *> (stmt));
1281               if (t != NULL_TREE)
1282                 ret |= build_access_from_expr (t, stmt, false);
1283               if (final_bbs)
1284                 bitmap_set_bit (final_bbs, bb->index);
1285               break;
1286
1287             case GIMPLE_ASSIGN:
1288               ret |= build_accesses_from_assign (stmt);
1289               break;
1290
1291             case GIMPLE_CALL:
1292               for (i = 0; i < gimple_call_num_args (stmt); i++)
1293                 ret |= build_access_from_expr (gimple_call_arg (stmt, i),
1294                                                stmt, false);
1295
1296               if (sra_mode == SRA_MODE_EARLY_IPA)
1297                 {
1298                   tree dest = gimple_call_fndecl (stmt);
1299                   int flags = gimple_call_flags (stmt);
1300
1301                   if (dest)
1302                     {
1303                       if (DECL_BUILT_IN_CLASS (dest) == BUILT_IN_NORMAL
1304                           && DECL_FUNCTION_CODE (dest) == BUILT_IN_APPLY_ARGS)
1305                         encountered_apply_args = true;
1306                       if (recursive_call_p (current_function_decl, dest))
1307                         {
1308                           encountered_recursive_call = true;
1309                           if (!callsite_arguments_match_p (stmt))
1310                             encountered_unchangable_recursive_call = true;
1311                         }
1312                     }
1313
1314                   if (final_bbs
1315                       && (flags & (ECF_CONST | ECF_PURE)) == 0)
1316                     bitmap_set_bit (final_bbs, bb->index);
1317                 }
1318
1319               t = gimple_call_lhs (stmt);
1320               if (t && !disqualify_if_bad_bb_terminating_stmt (stmt, t, NULL))
1321                 ret |= build_access_from_expr (t, stmt, true);
1322               break;
1323
1324             case GIMPLE_ASM:
1325               {
1326                 gasm *asm_stmt = as_a <gasm *> (stmt);
1327                 walk_stmt_load_store_addr_ops (asm_stmt, NULL, NULL, NULL,
1328                                                asm_visit_addr);
1329                 if (final_bbs)
1330                   bitmap_set_bit (final_bbs, bb->index);
1331
1332                 for (i = 0; i < gimple_asm_ninputs (asm_stmt); i++)
1333                   {
1334                     t = TREE_VALUE (gimple_asm_input_op (asm_stmt, i));
1335                     ret |= build_access_from_expr (t, asm_stmt, false);
1336                   }
1337                 for (i = 0; i < gimple_asm_noutputs (asm_stmt); i++)
1338                   {
1339                     t = TREE_VALUE (gimple_asm_output_op (asm_stmt, i));
1340                     ret |= build_access_from_expr (t, asm_stmt, true);
1341                   }
1342               }
1343               break;
1344
1345             default:
1346               break;
1347             }
1348         }
1349     }
1350
1351   return ret;
1352 }
1353
1354 /* Helper of QSORT function. There are pointers to accesses in the array.  An
1355    access is considered smaller than another if it has smaller offset or if the
1356    offsets are the same but is size is bigger. */
1357
1358 static int
1359 compare_access_positions (const void *a, const void *b)
1360 {
1361   const access_p *fp1 = (const access_p *) a;
1362   const access_p *fp2 = (const access_p *) b;
1363   const access_p f1 = *fp1;
1364   const access_p f2 = *fp2;
1365
1366   if (f1->offset != f2->offset)
1367     return f1->offset < f2->offset ? -1 : 1;
1368
1369   if (f1->size == f2->size)
1370     {
1371       if (f1->type == f2->type)
1372         return 0;
1373       /* Put any non-aggregate type before any aggregate type.  */
1374       else if (!is_gimple_reg_type (f1->type)
1375           && is_gimple_reg_type (f2->type))
1376         return 1;
1377       else if (is_gimple_reg_type (f1->type)
1378                && !is_gimple_reg_type (f2->type))
1379         return -1;
1380       /* Put any complex or vector type before any other scalar type.  */
1381       else if (TREE_CODE (f1->type) != COMPLEX_TYPE
1382                && TREE_CODE (f1->type) != VECTOR_TYPE
1383                && (TREE_CODE (f2->type) == COMPLEX_TYPE
1384                    || TREE_CODE (f2->type) == VECTOR_TYPE))
1385         return 1;
1386       else if ((TREE_CODE (f1->type) == COMPLEX_TYPE
1387                 || TREE_CODE (f1->type) == VECTOR_TYPE)
1388                && TREE_CODE (f2->type) != COMPLEX_TYPE
1389                && TREE_CODE (f2->type) != VECTOR_TYPE)
1390         return -1;
1391       /* Put the integral type with the bigger precision first.  */
1392       else if (INTEGRAL_TYPE_P (f1->type)
1393                && INTEGRAL_TYPE_P (f2->type))
1394         return TYPE_PRECISION (f2->type) - TYPE_PRECISION (f1->type);
1395       /* Put any integral type with non-full precision last.  */
1396       else if (INTEGRAL_TYPE_P (f1->type)
1397                && (TREE_INT_CST_LOW (TYPE_SIZE (f1->type))
1398                    != TYPE_PRECISION (f1->type)))
1399         return 1;
1400       else if (INTEGRAL_TYPE_P (f2->type)
1401                && (TREE_INT_CST_LOW (TYPE_SIZE (f2->type))
1402                    != TYPE_PRECISION (f2->type)))
1403         return -1;
1404       /* Stabilize the sort.  */
1405       return TYPE_UID (f1->type) - TYPE_UID (f2->type);
1406     }
1407
1408   /* We want the bigger accesses first, thus the opposite operator in the next
1409      line: */
1410   return f1->size > f2->size ? -1 : 1;
1411 }
1412
1413
1414 /* Append a name of the declaration to the name obstack.  A helper function for
1415    make_fancy_name.  */
1416
1417 static void
1418 make_fancy_decl_name (tree decl)
1419 {
1420   char buffer[32];
1421
1422   tree name = DECL_NAME (decl);
1423   if (name)
1424     obstack_grow (&name_obstack, IDENTIFIER_POINTER (name),
1425                   IDENTIFIER_LENGTH (name));
1426   else
1427     {
1428       sprintf (buffer, "D%u", DECL_UID (decl));
1429       obstack_grow (&name_obstack, buffer, strlen (buffer));
1430     }
1431 }
1432
1433 /* Helper for make_fancy_name.  */
1434
1435 static void
1436 make_fancy_name_1 (tree expr)
1437 {
1438   char buffer[32];
1439   tree index;
1440
1441   if (DECL_P (expr))
1442     {
1443       make_fancy_decl_name (expr);
1444       return;
1445     }
1446
1447   switch (TREE_CODE (expr))
1448     {
1449     case COMPONENT_REF:
1450       make_fancy_name_1 (TREE_OPERAND (expr, 0));
1451       obstack_1grow (&name_obstack, '$');
1452       make_fancy_decl_name (TREE_OPERAND (expr, 1));
1453       break;
1454
1455     case ARRAY_REF:
1456       make_fancy_name_1 (TREE_OPERAND (expr, 0));
1457       obstack_1grow (&name_obstack, '$');
1458       /* Arrays with only one element may not have a constant as their
1459          index. */
1460       index = TREE_OPERAND (expr, 1);
1461       if (TREE_CODE (index) != INTEGER_CST)
1462         break;
1463       sprintf (buffer, HOST_WIDE_INT_PRINT_DEC, TREE_INT_CST_LOW (index));
1464       obstack_grow (&name_obstack, buffer, strlen (buffer));
1465       break;
1466
1467     case ADDR_EXPR:
1468       make_fancy_name_1 (TREE_OPERAND (expr, 0));
1469       break;
1470
1471     case MEM_REF:
1472       make_fancy_name_1 (TREE_OPERAND (expr, 0));
1473       if (!integer_zerop (TREE_OPERAND (expr, 1)))
1474         {
1475           obstack_1grow (&name_obstack, '$');
1476           sprintf (buffer, HOST_WIDE_INT_PRINT_DEC,
1477                    TREE_INT_CST_LOW (TREE_OPERAND (expr, 1)));
1478           obstack_grow (&name_obstack, buffer, strlen (buffer));
1479         }
1480       break;
1481
1482     case BIT_FIELD_REF:
1483     case REALPART_EXPR:
1484     case IMAGPART_EXPR:
1485       gcc_unreachable ();       /* we treat these as scalars.  */
1486       break;
1487     default:
1488       break;
1489     }
1490 }
1491
1492 /* Create a human readable name for replacement variable of ACCESS.  */
1493
1494 static char *
1495 make_fancy_name (tree expr)
1496 {
1497   make_fancy_name_1 (expr);
1498   obstack_1grow (&name_obstack, '\0');
1499   return XOBFINISH (&name_obstack, char *);
1500 }
1501
1502 /* Construct a MEM_REF that would reference a part of aggregate BASE of type
1503    EXP_TYPE at the given OFFSET.  If BASE is something for which
1504    get_addr_base_and_unit_offset returns NULL, gsi must be non-NULL and is used
1505    to insert new statements either before or below the current one as specified
1506    by INSERT_AFTER.  This function is not capable of handling bitfields.
1507
1508    BASE must be either a declaration or a memory reference that has correct
1509    alignment ifformation embeded in it (e.g. a pre-existing one in SRA).  */
1510
1511 tree
1512 build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
1513                       tree exp_type, gimple_stmt_iterator *gsi,
1514                       bool insert_after)
1515 {
1516   tree prev_base = base;
1517   tree off;
1518   tree mem_ref;
1519   HOST_WIDE_INT base_offset;
1520   unsigned HOST_WIDE_INT misalign;
1521   unsigned int align;
1522
1523   gcc_checking_assert (offset % BITS_PER_UNIT == 0);
1524   get_object_alignment_1 (base, &align, &misalign);
1525   base = get_addr_base_and_unit_offset (base, &base_offset);
1526
1527   /* get_addr_base_and_unit_offset returns NULL for references with a variable
1528      offset such as array[var_index].  */
1529   if (!base)
1530     {
1531       gassign *stmt;
1532       tree tmp, addr;
1533
1534       gcc_checking_assert (gsi);
1535       tmp = make_ssa_name (build_pointer_type (TREE_TYPE (prev_base)));
1536       addr = build_fold_addr_expr (unshare_expr (prev_base));
1537       STRIP_USELESS_TYPE_CONVERSION (addr);
1538       stmt = gimple_build_assign (tmp, addr);
1539       gimple_set_location (stmt, loc);
1540       if (insert_after)
1541         gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
1542       else
1543         gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
1544
1545       off = build_int_cst (reference_alias_ptr_type (prev_base),
1546                            offset / BITS_PER_UNIT);
1547       base = tmp;
1548     }
1549   else if (TREE_CODE (base) == MEM_REF)
1550     {
1551       off = build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)),
1552                            base_offset + offset / BITS_PER_UNIT);
1553       off = int_const_binop (PLUS_EXPR, TREE_OPERAND (base, 1), off);
1554       base = unshare_expr (TREE_OPERAND (base, 0));
1555     }
1556   else
1557     {
1558       off = build_int_cst (reference_alias_ptr_type (base),
1559                            base_offset + offset / BITS_PER_UNIT);
1560       base = build_fold_addr_expr (unshare_expr (base));
1561     }
1562
1563   misalign = (misalign + offset) & (align - 1);
1564   if (misalign != 0)
1565     align = (misalign & -misalign);
1566   if (align != TYPE_ALIGN (exp_type))
1567     exp_type = build_aligned_type (exp_type, align);
1568
1569   mem_ref = fold_build2_loc (loc, MEM_REF, exp_type, base, off);
1570   if (TREE_THIS_VOLATILE (prev_base))
1571     TREE_THIS_VOLATILE (mem_ref) = 1;
1572   if (TREE_SIDE_EFFECTS (prev_base))
1573     TREE_SIDE_EFFECTS (mem_ref) = 1;
1574   return mem_ref;
1575 }
1576
1577 /* Construct a memory reference to a part of an aggregate BASE at the given
1578    OFFSET and of the same type as MODEL.  In case this is a reference to a
1579    bit-field, the function will replicate the last component_ref of model's
1580    expr to access it.  GSI and INSERT_AFTER have the same meaning as in
1581    build_ref_for_offset.  */
1582
1583 static tree
1584 build_ref_for_model (location_t loc, tree base, HOST_WIDE_INT offset,
1585                      struct access *model, gimple_stmt_iterator *gsi,
1586                      bool insert_after)
1587 {
1588   if (TREE_CODE (model->expr) == COMPONENT_REF
1589       && DECL_BIT_FIELD (TREE_OPERAND (model->expr, 1)))
1590     {
1591       /* This access represents a bit-field.  */
1592       tree t, exp_type, fld = TREE_OPERAND (model->expr, 1);
1593
1594       offset -= int_bit_position (fld);
1595       exp_type = TREE_TYPE (TREE_OPERAND (model->expr, 0));
1596       t = build_ref_for_offset (loc, base, offset, exp_type, gsi, insert_after);
1597       return fold_build3_loc (loc, COMPONENT_REF, TREE_TYPE (fld), t, fld,
1598                               NULL_TREE);
1599     }
1600   else
1601     return build_ref_for_offset (loc, base, offset, model->type,
1602                                  gsi, insert_after);
1603 }
1604
1605 /* Attempt to build a memory reference that we could but into a gimple
1606    debug_bind statement.  Similar to build_ref_for_model but punts if it has to
1607    create statements and return s NULL instead.  This function also ignores
1608    alignment issues and so its results should never end up in non-debug
1609    statements.  */
1610
1611 static tree
1612 build_debug_ref_for_model (location_t loc, tree base, HOST_WIDE_INT offset,
1613                            struct access *model)
1614 {
1615   HOST_WIDE_INT base_offset;
1616   tree off;
1617
1618   if (TREE_CODE (model->expr) == COMPONENT_REF
1619       && DECL_BIT_FIELD (TREE_OPERAND (model->expr, 1)))
1620     return NULL_TREE;
1621
1622   base = get_addr_base_and_unit_offset (base, &base_offset);
1623   if (!base)
1624     return NULL_TREE;
1625   if (TREE_CODE (base) == MEM_REF)
1626     {
1627       off = build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)),
1628                            base_offset + offset / BITS_PER_UNIT);
1629       off = int_const_binop (PLUS_EXPR, TREE_OPERAND (base, 1), off);
1630       base = unshare_expr (TREE_OPERAND (base, 0));
1631     }
1632   else
1633     {
1634       off = build_int_cst (reference_alias_ptr_type (base),
1635                            base_offset + offset / BITS_PER_UNIT);
1636       base = build_fold_addr_expr (unshare_expr (base));
1637     }
1638
1639   return fold_build2_loc (loc, MEM_REF, model->type, base, off);
1640 }
1641
1642 /* Construct a memory reference consisting of component_refs and array_refs to
1643    a part of an aggregate *RES (which is of type TYPE).  The requested part
1644    should have type EXP_TYPE at be the given OFFSET.  This function might not
1645    succeed, it returns true when it does and only then *RES points to something
1646    meaningful.  This function should be used only to build expressions that we
1647    might need to present to user (e.g. in warnings).  In all other situations,
1648    build_ref_for_model or build_ref_for_offset should be used instead.  */
1649
1650 static bool
1651 build_user_friendly_ref_for_offset (tree *res, tree type, HOST_WIDE_INT offset,
1652                                     tree exp_type)
1653 {
1654   while (1)
1655     {
1656       tree fld;
1657       tree tr_size, index, minidx;
1658       HOST_WIDE_INT el_size;
1659
1660       if (offset == 0 && exp_type
1661           && types_compatible_p (exp_type, type))
1662         return true;
1663
1664       switch (TREE_CODE (type))
1665         {
1666         case UNION_TYPE:
1667         case QUAL_UNION_TYPE:
1668         case RECORD_TYPE:
1669           for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
1670             {
1671               HOST_WIDE_INT pos, size;
1672               tree tr_pos, expr, *expr_ptr;
1673
1674               if (TREE_CODE (fld) != FIELD_DECL)
1675                 continue;
1676
1677               tr_pos = bit_position (fld);
1678               if (!tr_pos || !tree_fits_uhwi_p (tr_pos))
1679                 continue;
1680               pos = tree_to_uhwi (tr_pos);
1681               gcc_assert (TREE_CODE (type) == RECORD_TYPE || pos == 0);
1682               tr_size = DECL_SIZE (fld);
1683               if (!tr_size || !tree_fits_uhwi_p (tr_size))
1684                 continue;
1685               size = tree_to_uhwi (tr_size);
1686               if (size == 0)
1687                 {
1688                   if (pos != offset)
1689                     continue;
1690                 }
1691               else if (pos > offset || (pos + size) <= offset)
1692                 continue;
1693
1694               expr = build3 (COMPONENT_REF, TREE_TYPE (fld), *res, fld,
1695                              NULL_TREE);
1696               expr_ptr = &expr;
1697               if (build_user_friendly_ref_for_offset (expr_ptr, TREE_TYPE (fld),
1698                                                       offset - pos, exp_type))
1699                 {
1700                   *res = expr;
1701                   return true;
1702                 }
1703             }
1704           return false;
1705
1706         case ARRAY_TYPE:
1707           tr_size = TYPE_SIZE (TREE_TYPE (type));
1708           if (!tr_size || !tree_fits_uhwi_p (tr_size))
1709             return false;
1710           el_size = tree_to_uhwi (tr_size);
1711
1712           minidx = TYPE_MIN_VALUE (TYPE_DOMAIN (type));
1713           if (TREE_CODE (minidx) != INTEGER_CST || el_size == 0)
1714             return false;
1715           index = build_int_cst (TYPE_DOMAIN (type), offset / el_size);
1716           if (!integer_zerop (minidx))
1717             index = int_const_binop (PLUS_EXPR, index, minidx);
1718           *res = build4 (ARRAY_REF, TREE_TYPE (type), *res, index,
1719                          NULL_TREE, NULL_TREE);
1720           offset = offset % el_size;
1721           type = TREE_TYPE (type);
1722           break;
1723
1724         default:
1725           if (offset != 0)
1726             return false;
1727
1728           if (exp_type)
1729             return false;
1730           else
1731             return true;
1732         }
1733     }
1734 }
1735
1736 /* Return true iff TYPE is stdarg va_list type.  */
1737
1738 static inline bool
1739 is_va_list_type (tree type)
1740 {
1741   return TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (va_list_type_node);
1742 }
1743
1744 /* Print message to dump file why a variable was rejected. */
1745
1746 static void
1747 reject (tree var, const char *msg)
1748 {
1749   if (dump_file && (dump_flags & TDF_DETAILS))
1750     {
1751       fprintf (dump_file, "Rejected (%d): %s: ", DECL_UID (var), msg);
1752       print_generic_expr (dump_file, var, 0);
1753       fprintf (dump_file, "\n");
1754     }
1755 }
1756
1757 /* Return true if VAR is a candidate for SRA.  */
1758
1759 static bool
1760 maybe_add_sra_candidate (tree var)
1761 {
1762   tree type = TREE_TYPE (var);
1763   const char *msg;
1764   tree_node **slot;
1765
1766   if (!AGGREGATE_TYPE_P (type))
1767     {
1768       reject (var, "not aggregate");
1769       return false;
1770     }
1771   if (needs_to_live_in_memory (var))
1772     {
1773       reject (var, "needs to live in memory");
1774       return false;
1775     }
1776   if (TREE_THIS_VOLATILE (var))
1777     {
1778       reject (var, "is volatile");
1779       return false;
1780     }
1781   if (!COMPLETE_TYPE_P (type))
1782     {
1783       reject (var, "has incomplete type");
1784       return false;
1785     }
1786   if (!tree_fits_uhwi_p (TYPE_SIZE (type)))
1787     {
1788       reject (var, "type size not fixed");
1789       return false;
1790     }
1791   if (tree_to_uhwi (TYPE_SIZE (type)) == 0)
1792     {
1793       reject (var, "type size is zero");
1794       return false;
1795     }
1796   if (type_internals_preclude_sra_p (type, &msg))
1797     {
1798       reject (var, msg);
1799       return false;
1800     }
1801   if (/* Fix for PR 41089.  tree-stdarg.c needs to have va_lists intact but
1802          we also want to schedule it rather late.  Thus we ignore it in
1803          the early pass. */
1804       (sra_mode == SRA_MODE_EARLY_INTRA
1805        && is_va_list_type (type)))
1806     {
1807       reject (var, "is va_list");
1808       return false;
1809     }
1810
1811   bitmap_set_bit (candidate_bitmap, DECL_UID (var));
1812   slot = candidates->find_slot_with_hash (var, DECL_UID (var), INSERT);
1813   *slot = var;
1814
1815   if (dump_file && (dump_flags & TDF_DETAILS))
1816     {
1817       fprintf (dump_file, "Candidate (%d): ", DECL_UID (var));
1818       print_generic_expr (dump_file, var, 0);
1819       fprintf (dump_file, "\n");
1820     }
1821
1822   return true;
1823 }
1824
1825 /* The very first phase of intraprocedural SRA.  It marks in candidate_bitmap
1826    those with type which is suitable for scalarization.  */
1827
1828 static bool
1829 find_var_candidates (void)
1830 {
1831   tree var, parm;
1832   unsigned int i;
1833   bool ret = false;
1834
1835   for (parm = DECL_ARGUMENTS (current_function_decl);
1836        parm;
1837        parm = DECL_CHAIN (parm))
1838     ret |= maybe_add_sra_candidate (parm);
1839
1840   FOR_EACH_LOCAL_DECL (cfun, i, var)
1841     {
1842       if (TREE_CODE (var) != VAR_DECL)
1843         continue;
1844
1845       ret |= maybe_add_sra_candidate (var);
1846     }
1847
1848   return ret;
1849 }
1850
1851 /* Sort all accesses for the given variable, check for partial overlaps and
1852    return NULL if there are any.  If there are none, pick a representative for
1853    each combination of offset and size and create a linked list out of them.
1854    Return the pointer to the first representative and make sure it is the first
1855    one in the vector of accesses.  */
1856
1857 static struct access *
1858 sort_and_splice_var_accesses (tree var)
1859 {
1860   int i, j, access_count;
1861   struct access *res, **prev_acc_ptr = &res;
1862   vec<access_p> *access_vec;
1863   bool first = true;
1864   HOST_WIDE_INT low = -1, high = 0;
1865
1866   access_vec = get_base_access_vector (var);
1867   if (!access_vec)
1868     return NULL;
1869   access_count = access_vec->length ();
1870
1871   /* Sort by <OFFSET, SIZE>.  */
1872   access_vec->qsort (compare_access_positions);
1873
1874   i = 0;
1875   while (i < access_count)
1876     {
1877       struct access *access = (*access_vec)[i];
1878       bool grp_write = access->write;
1879       bool grp_read = !access->write;
1880       bool grp_scalar_write = access->write
1881         && is_gimple_reg_type (access->type);
1882       bool grp_scalar_read = !access->write
1883         && is_gimple_reg_type (access->type);
1884       bool grp_assignment_read = access->grp_assignment_read;
1885       bool grp_assignment_write = access->grp_assignment_write;
1886       bool multiple_scalar_reads = false;
1887       bool total_scalarization = access->grp_total_scalarization;
1888       bool grp_partial_lhs = access->grp_partial_lhs;
1889       bool first_scalar = is_gimple_reg_type (access->type);
1890       bool unscalarizable_region = access->grp_unscalarizable_region;
1891
1892       if (first || access->offset >= high)
1893         {
1894           first = false;
1895           low = access->offset;
1896           high = access->offset + access->size;
1897         }
1898       else if (access->offset > low && access->offset + access->size > high)
1899         return NULL;
1900       else
1901         gcc_assert (access->offset >= low
1902                     && access->offset + access->size <= high);
1903
1904       j = i + 1;
1905       while (j < access_count)
1906         {
1907           struct access *ac2 = (*access_vec)[j];
1908           if (ac2->offset != access->offset || ac2->size != access->size)
1909             break;
1910           if (ac2->write)
1911             {
1912               grp_write = true;
1913               grp_scalar_write = (grp_scalar_write
1914                                   || is_gimple_reg_type (ac2->type));
1915             }
1916           else
1917             {
1918               grp_read = true;
1919               if (is_gimple_reg_type (ac2->type))
1920                 {
1921                   if (grp_scalar_read)
1922                     multiple_scalar_reads = true;
1923                   else
1924                     grp_scalar_read = true;
1925                 }
1926             }
1927           grp_assignment_read |= ac2->grp_assignment_read;
1928           grp_assignment_write |= ac2->grp_assignment_write;
1929           grp_partial_lhs |= ac2->grp_partial_lhs;
1930           unscalarizable_region |= ac2->grp_unscalarizable_region;
1931           total_scalarization |= ac2->grp_total_scalarization;
1932           relink_to_new_repr (access, ac2);
1933
1934           /* If there are both aggregate-type and scalar-type accesses with
1935              this combination of size and offset, the comparison function
1936              should have put the scalars first.  */
1937           gcc_assert (first_scalar || !is_gimple_reg_type (ac2->type));
1938           ac2->group_representative = access;
1939           j++;
1940         }
1941
1942       i = j;
1943
1944       access->group_representative = access;
1945       access->grp_write = grp_write;
1946       access->grp_read = grp_read;
1947       access->grp_scalar_read = grp_scalar_read;
1948       access->grp_scalar_write = grp_scalar_write;
1949       access->grp_assignment_read = grp_assignment_read;
1950       access->grp_assignment_write = grp_assignment_write;
1951       access->grp_hint = multiple_scalar_reads || total_scalarization;
1952       access->grp_total_scalarization = total_scalarization;
1953       access->grp_partial_lhs = grp_partial_lhs;
1954       access->grp_unscalarizable_region = unscalarizable_region;
1955       if (access->first_link)
1956         add_access_to_work_queue (access);
1957
1958       *prev_acc_ptr = access;
1959       prev_acc_ptr = &access->next_grp;
1960     }
1961
1962   gcc_assert (res == (*access_vec)[0]);
1963   return res;
1964 }
1965
1966 /* Create a variable for the given ACCESS which determines the type, name and a
1967    few other properties.  Return the variable declaration and store it also to
1968    ACCESS->replacement.  */
1969
1970 static tree
1971 create_access_replacement (struct access *access)
1972 {
1973   tree repl;
1974
1975   if (access->grp_to_be_debug_replaced)
1976     {
1977       repl = create_tmp_var_raw (access->type);
1978       DECL_CONTEXT (repl) = current_function_decl;
1979     }
1980   else
1981     /* Drop any special alignment on the type if it's not on the main
1982        variant.  This avoids issues with weirdo ABIs like AAPCS.  */
1983     repl = create_tmp_var (build_qualified_type
1984                              (TYPE_MAIN_VARIANT (access->type),
1985                               TYPE_QUALS (access->type)), "SR");
1986   if (TREE_CODE (access->type) == COMPLEX_TYPE
1987       || TREE_CODE (access->type) == VECTOR_TYPE)
1988     {
1989       if (!access->grp_partial_lhs)
1990         DECL_GIMPLE_REG_P (repl) = 1;
1991     }
1992   else if (access->grp_partial_lhs
1993            && is_gimple_reg_type (access->type))
1994     TREE_ADDRESSABLE (repl) = 1;
1995
1996   DECL_SOURCE_LOCATION (repl) = DECL_SOURCE_LOCATION (access->base);
1997   DECL_ARTIFICIAL (repl) = 1;
1998   DECL_IGNORED_P (repl) = DECL_IGNORED_P (access->base);
1999
2000   if (DECL_NAME (access->base)
2001       && !DECL_IGNORED_P (access->base)
2002       && !DECL_ARTIFICIAL (access->base))
2003     {
2004       char *pretty_name = make_fancy_name (access->expr);
2005       tree debug_expr = unshare_expr_without_location (access->expr), d;
2006       bool fail = false;
2007
2008       DECL_NAME (repl) = get_identifier (pretty_name);
2009       obstack_free (&name_obstack, pretty_name);
2010
2011       /* Get rid of any SSA_NAMEs embedded in debug_expr,
2012          as DECL_DEBUG_EXPR isn't considered when looking for still
2013          used SSA_NAMEs and thus they could be freed.  All debug info
2014          generation cares is whether something is constant or variable
2015          and that get_ref_base_and_extent works properly on the
2016          expression.  It cannot handle accesses at a non-constant offset
2017          though, so just give up in those cases.  */
2018       for (d = debug_expr;
2019            !fail && (handled_component_p (d) || TREE_CODE (d) == MEM_REF);
2020            d = TREE_OPERAND (d, 0))
2021         switch (TREE_CODE (d))
2022           {
2023           case ARRAY_REF:
2024           case ARRAY_RANGE_REF:
2025             if (TREE_OPERAND (d, 1)
2026                 && TREE_CODE (TREE_OPERAND (d, 1)) != INTEGER_CST)
2027               fail = true;
2028             if (TREE_OPERAND (d, 3)
2029                 && TREE_CODE (TREE_OPERAND (d, 3)) != INTEGER_CST)
2030               fail = true;
2031             /* FALLTHRU */
2032           case COMPONENT_REF:
2033             if (TREE_OPERAND (d, 2)
2034                 && TREE_CODE (TREE_OPERAND (d, 2)) != INTEGER_CST)
2035               fail = true;
2036             break;
2037           case MEM_REF:
2038             if (TREE_CODE (TREE_OPERAND (d, 0)) != ADDR_EXPR)
2039               fail = true;
2040             else
2041               d = TREE_OPERAND (d, 0);
2042             break;
2043           default:
2044             break;
2045           }
2046       if (!fail)
2047         {
2048           SET_DECL_DEBUG_EXPR (repl, debug_expr);
2049           DECL_HAS_DEBUG_EXPR_P (repl) = 1;
2050         }
2051       if (access->grp_no_warning)
2052         TREE_NO_WARNING (repl) = 1;
2053       else
2054         TREE_NO_WARNING (repl) = TREE_NO_WARNING (access->base);
2055     }
2056   else
2057     TREE_NO_WARNING (repl) = 1;
2058
2059   if (dump_file)
2060     {
2061       if (access->grp_to_be_debug_replaced)
2062         {
2063           fprintf (dump_file, "Created a debug-only replacement for ");
2064           print_generic_expr (dump_file, access->base, 0);
2065           fprintf (dump_file, " offset: %u, size: %u\n",
2066                    (unsigned) access->offset, (unsigned) access->size);
2067         }
2068       else
2069         {
2070           fprintf (dump_file, "Created a replacement for ");
2071           print_generic_expr (dump_file, access->base, 0);
2072           fprintf (dump_file, " offset: %u, size: %u: ",
2073                    (unsigned) access->offset, (unsigned) access->size);
2074           print_generic_expr (dump_file, repl, 0);
2075           fprintf (dump_file, "\n");
2076         }
2077     }
2078   sra_stats.replacements++;
2079
2080   return repl;
2081 }
2082
2083 /* Return ACCESS scalar replacement, create it if it does not exist yet.  */
2084
2085 static inline tree
2086 get_access_replacement (struct access *access)
2087 {
2088   gcc_checking_assert (access->replacement_decl);
2089   return access->replacement_decl;
2090 }
2091
2092
2093 /* Build a subtree of accesses rooted in *ACCESS, and move the pointer in the
2094    linked list along the way.  Stop when *ACCESS is NULL or the access pointed
2095    to it is not "within" the root.  Return false iff some accesses partially
2096    overlap.  */
2097
2098 static bool
2099 build_access_subtree (struct access **access)
2100 {
2101   struct access *root = *access, *last_child = NULL;
2102   HOST_WIDE_INT limit = root->offset + root->size;
2103
2104   *access = (*access)->next_grp;
2105   while  (*access && (*access)->offset + (*access)->size <= limit)
2106     {
2107       if (!last_child)
2108         root->first_child = *access;
2109       else
2110         last_child->next_sibling = *access;
2111       last_child = *access;
2112
2113       if (!build_access_subtree (access))
2114         return false;
2115     }
2116
2117   if (*access && (*access)->offset < limit)
2118     return false;
2119
2120   return true;
2121 }
2122
2123 /* Build a tree of access representatives, ACCESS is the pointer to the first
2124    one, others are linked in a list by the next_grp field.  Return false iff
2125    some accesses partially overlap.  */
2126
2127 static bool
2128 build_access_trees (struct access *access)
2129 {
2130   while (access)
2131     {
2132       struct access *root = access;
2133
2134       if (!build_access_subtree (&access))
2135         return false;
2136       root->next_grp = access;
2137     }
2138   return true;
2139 }
2140
2141 /* Return true if expr contains some ARRAY_REFs into a variable bounded
2142    array.  */
2143
2144 static bool
2145 expr_with_var_bounded_array_refs_p (tree expr)
2146 {
2147   while (handled_component_p (expr))
2148     {
2149       if (TREE_CODE (expr) == ARRAY_REF
2150           && !tree_fits_shwi_p (array_ref_low_bound (expr)))
2151         return true;
2152       expr = TREE_OPERAND (expr, 0);
2153     }
2154   return false;
2155 }
2156
2157 /* Analyze the subtree of accesses rooted in ROOT, scheduling replacements when
2158    both seeming beneficial and when ALLOW_REPLACEMENTS allows it.  Also set all
2159    sorts of access flags appropriately along the way, notably always set
2160    grp_read and grp_assign_read according to MARK_READ and grp_write when
2161    MARK_WRITE is true.
2162
2163    Creating a replacement for a scalar access is considered beneficial if its
2164    grp_hint is set (this means we are either attempting total scalarization or
2165    there is more than one direct read access) or according to the following
2166    table:
2167
2168    Access written to through a scalar type (once or more times)
2169    |
2170    |    Written to in an assignment statement
2171    |    |
2172    |    |       Access read as scalar _once_
2173    |    |       |
2174    |    |       |       Read in an assignment statement
2175    |    |       |       |
2176    |    |       |       |       Scalarize       Comment
2177 -----------------------------------------------------------------------------
2178    0    0       0       0                       No access for the scalar
2179    0    0       0       1                       No access for the scalar
2180    0    0       1       0       No              Single read - won't help
2181    0    0       1       1       No              The same case
2182    0    1       0       0                       No access for the scalar
2183    0    1       0       1                       No access for the scalar
2184    0    1       1       0       Yes             s = *g; return s.i;
2185    0    1       1       1       Yes             The same case as above
2186    1    0       0       0       No              Won't help
2187    1    0       0       1       Yes             s.i = 1; *g = s;
2188    1    0       1       0       Yes             s.i = 5; g = s.i;
2189    1    0       1       1       Yes             The same case as above
2190    1    1       0       0       No              Won't help.
2191    1    1       0       1       Yes             s.i = 1; *g = s;
2192    1    1       1       0       Yes             s = *g; return s.i;
2193    1    1       1       1       Yes             Any of the above yeses  */
2194
2195 static bool
2196 analyze_access_subtree (struct access *root, struct access *parent,
2197                         bool allow_replacements)
2198 {
2199   struct access *child;
2200   HOST_WIDE_INT limit = root->offset + root->size;
2201   HOST_WIDE_INT covered_to = root->offset;
2202   bool scalar = is_gimple_reg_type (root->type);
2203   bool hole = false, sth_created = false;
2204
2205   if (parent)
2206     {
2207       if (parent->grp_read)
2208         root->grp_read = 1;
2209       if (parent->grp_assignment_read)
2210         root->grp_assignment_read = 1;
2211       if (parent->grp_write)
2212         root->grp_write = 1;
2213       if (parent->grp_assignment_write)
2214         root->grp_assignment_write = 1;
2215       if (parent->grp_total_scalarization)
2216         root->grp_total_scalarization = 1;
2217     }
2218
2219   if (root->grp_unscalarizable_region)
2220     allow_replacements = false;
2221
2222   if (allow_replacements && expr_with_var_bounded_array_refs_p (root->expr))
2223     allow_replacements = false;
2224
2225   for (child = root->first_child; child; child = child->next_sibling)
2226     {
2227       hole |= covered_to < child->offset;
2228       sth_created |= analyze_access_subtree (child, root,
2229                                              allow_replacements && !scalar);
2230
2231       root->grp_unscalarized_data |= child->grp_unscalarized_data;
2232       root->grp_total_scalarization &= child->grp_total_scalarization;
2233       if (child->grp_covered)
2234         covered_to += child->size;
2235       else
2236         hole = true;
2237     }
2238
2239   if (allow_replacements && scalar && !root->first_child
2240       && (root->grp_hint
2241           || ((root->grp_scalar_read || root->grp_assignment_read)
2242               && (root->grp_scalar_write || root->grp_assignment_write))))
2243     {
2244       /* Always create access replacements that cover the whole access.
2245          For integral types this means the precision has to match.
2246          Avoid assumptions based on the integral type kind, too.  */
2247       if (INTEGRAL_TYPE_P (root->type)
2248           && (TREE_CODE (root->type) != INTEGER_TYPE
2249               || TYPE_PRECISION (root->type) != root->size)
2250           /* But leave bitfield accesses alone.  */
2251           && (TREE_CODE (root->expr) != COMPONENT_REF
2252               || !DECL_BIT_FIELD (TREE_OPERAND (root->expr, 1))))
2253         {
2254           tree rt = root->type;
2255           gcc_assert ((root->offset % BITS_PER_UNIT) == 0
2256                       && (root->size % BITS_PER_UNIT) == 0);
2257           root->type = build_nonstandard_integer_type (root->size,
2258                                                        TYPE_UNSIGNED (rt));
2259           root->expr = build_ref_for_offset (UNKNOWN_LOCATION,
2260                                              root->base, root->offset,
2261                                              root->type, NULL, false);
2262
2263           if (dump_file && (dump_flags & TDF_DETAILS))
2264             {
2265               fprintf (dump_file, "Changing the type of a replacement for ");
2266               print_generic_expr (dump_file, root->base, 0);
2267               fprintf (dump_file, " offset: %u, size: %u ",
2268                        (unsigned) root->offset, (unsigned) root->size);
2269               fprintf (dump_file, " to an integer.\n");
2270             }
2271         }
2272
2273       root->grp_to_be_replaced = 1;
2274       root->replacement_decl = create_access_replacement (root);
2275       sth_created = true;
2276       hole = false;
2277     }
2278   else
2279     {
2280       if (allow_replacements
2281           && scalar && !root->first_child
2282           && (root->grp_scalar_write || root->grp_assignment_write)
2283           && !bitmap_bit_p (cannot_scalarize_away_bitmap,
2284                             DECL_UID (root->base)))
2285         {
2286           gcc_checking_assert (!root->grp_scalar_read
2287                                && !root->grp_assignment_read);
2288           sth_created = true;
2289           if (MAY_HAVE_DEBUG_STMTS)
2290             {
2291               root->grp_to_be_debug_replaced = 1;
2292               root->replacement_decl = create_access_replacement (root);
2293             }
2294         }
2295
2296       if (covered_to < limit)
2297         hole = true;
2298       if (scalar)
2299         root->grp_total_scalarization = 0;
2300     }
2301
2302   if (!hole || root->grp_total_scalarization)
2303     root->grp_covered = 1;
2304   else if (root->grp_write || TREE_CODE (root->base) == PARM_DECL)
2305     root->grp_unscalarized_data = 1; /* not covered and written to */
2306   return sth_created;
2307 }
2308
2309 /* Analyze all access trees linked by next_grp by the means of
2310    analyze_access_subtree.  */
2311 static bool
2312 analyze_access_trees (struct access *access)
2313 {
2314   bool ret = false;
2315
2316   while (access)
2317     {
2318       if (analyze_access_subtree (access, NULL, true))
2319         ret = true;
2320       access = access->next_grp;
2321     }
2322
2323   return ret;
2324 }
2325
2326 /* Return true iff a potential new child of LACC at offset OFFSET and with size
2327    SIZE would conflict with an already existing one.  If exactly such a child
2328    already exists in LACC, store a pointer to it in EXACT_MATCH.  */
2329
2330 static bool
2331 child_would_conflict_in_lacc (struct access *lacc, HOST_WIDE_INT norm_offset,
2332                               HOST_WIDE_INT size, struct access **exact_match)
2333 {
2334   struct access *child;
2335
2336   for (child = lacc->first_child; child; child = child->next_sibling)
2337     {
2338       if (child->offset == norm_offset && child->size == size)
2339         {
2340           *exact_match = child;
2341           return true;
2342         }
2343
2344       if (child->offset < norm_offset + size
2345           && child->offset + child->size > norm_offset)
2346         return true;
2347     }
2348
2349   return false;
2350 }
2351
2352 /* Create a new child access of PARENT, with all properties just like MODEL
2353    except for its offset and with its grp_write false and grp_read true.
2354    Return the new access or NULL if it cannot be created.  Note that this access
2355    is created long after all splicing and sorting, it's not located in any
2356    access vector and is automatically a representative of its group.  */
2357
2358 static struct access *
2359 create_artificial_child_access (struct access *parent, struct access *model,
2360                                 HOST_WIDE_INT new_offset)
2361 {
2362   struct access **child;
2363   tree expr = parent->base;
2364
2365   gcc_assert (!model->grp_unscalarizable_region);
2366
2367   struct access *access = access_pool.allocate ();
2368   memset (access, 0, sizeof (struct access));
2369   if (!build_user_friendly_ref_for_offset (&expr, TREE_TYPE (expr), new_offset,
2370                                            model->type))
2371     {
2372       access->grp_no_warning = true;
2373       expr = build_ref_for_model (EXPR_LOCATION (parent->base), parent->base,
2374                                   new_offset, model, NULL, false);
2375     }
2376
2377   access->base = parent->base;
2378   access->expr = expr;
2379   access->offset = new_offset;
2380   access->size = model->size;
2381   access->type = model->type;
2382   access->grp_write = true;
2383   access->grp_read = false;
2384
2385   child = &parent->first_child;
2386   while (*child && (*child)->offset < new_offset)
2387     child = &(*child)->next_sibling;
2388
2389   access->next_sibling = *child;
2390   *child = access;
2391
2392   return access;
2393 }
2394
2395
2396 /* Propagate all subaccesses of RACC across an assignment link to LACC. Return
2397    true if any new subaccess was created.  Additionally, if RACC is a scalar
2398    access but LACC is not, change the type of the latter, if possible.  */
2399
2400 static bool
2401 propagate_subaccesses_across_link (struct access *lacc, struct access *racc)
2402 {
2403   struct access *rchild;
2404   HOST_WIDE_INT norm_delta = lacc->offset - racc->offset;
2405   bool ret = false;
2406
2407   if (is_gimple_reg_type (lacc->type)
2408       || lacc->grp_unscalarizable_region
2409       || racc->grp_unscalarizable_region)
2410     return false;
2411
2412   if (is_gimple_reg_type (racc->type))
2413     {
2414       if (!lacc->first_child && !racc->first_child)
2415         {
2416           tree t = lacc->base;
2417
2418           lacc->type = racc->type;
2419           if (build_user_friendly_ref_for_offset (&t, TREE_TYPE (t),
2420                                                   lacc->offset, racc->type))
2421             lacc->expr = t;
2422           else
2423             {
2424               lacc->expr = build_ref_for_model (EXPR_LOCATION (lacc->base),
2425                                                 lacc->base, lacc->offset,
2426                                                 racc, NULL, false);
2427               lacc->grp_no_warning = true;
2428             }
2429         }
2430       return false;
2431     }
2432
2433   for (rchild = racc->first_child; rchild; rchild = rchild->next_sibling)
2434     {
2435       struct access *new_acc = NULL;
2436       HOST_WIDE_INT norm_offset = rchild->offset + norm_delta;
2437
2438       if (rchild->grp_unscalarizable_region)
2439         continue;
2440
2441       if (child_would_conflict_in_lacc (lacc, norm_offset, rchild->size,
2442                                         &new_acc))
2443         {
2444           if (new_acc)
2445             {
2446               rchild->grp_hint = 1;
2447               new_acc->grp_hint |= new_acc->grp_read;
2448               if (rchild->first_child)
2449                 ret |= propagate_subaccesses_across_link (new_acc, rchild);
2450             }
2451           continue;
2452         }
2453
2454       rchild->grp_hint = 1;
2455       new_acc = create_artificial_child_access (lacc, rchild, norm_offset);
2456       if (new_acc)
2457         {
2458           ret = true;
2459           if (racc->first_child)
2460             propagate_subaccesses_across_link (new_acc, rchild);
2461         }
2462     }
2463
2464   return ret;
2465 }
2466
2467 /* Propagate all subaccesses across assignment links.  */
2468
2469 static void
2470 propagate_all_subaccesses (void)
2471 {
2472   while (work_queue_head)
2473     {
2474       struct access *racc = pop_access_from_work_queue ();
2475       struct assign_link *link;
2476
2477       gcc_assert (racc->first_link);
2478
2479       for (link = racc->first_link; link; link = link->next)
2480         {
2481           struct access *lacc = link->lacc;
2482
2483           if (!bitmap_bit_p (candidate_bitmap, DECL_UID (lacc->base)))
2484             continue;
2485           lacc = lacc->group_representative;
2486           if (propagate_subaccesses_across_link (lacc, racc)
2487               && lacc->first_link)
2488             add_access_to_work_queue (lacc);
2489         }
2490     }
2491 }
2492
2493 /* Go through all accesses collected throughout the (intraprocedural) analysis
2494    stage, exclude overlapping ones, identify representatives and build trees
2495    out of them, making decisions about scalarization on the way.  Return true
2496    iff there are any to-be-scalarized variables after this stage. */
2497
2498 static bool
2499 analyze_all_variable_accesses (void)
2500 {
2501   int res = 0;
2502   bitmap tmp = BITMAP_ALLOC (NULL);
2503   bitmap_iterator bi;
2504   unsigned i;
2505   bool optimize_speed_p = !optimize_function_for_size_p (cfun);
2506
2507   enum compiler_param param = optimize_speed_p
2508                         ? PARAM_SRA_MAX_SCALARIZATION_SIZE_SPEED
2509                         : PARAM_SRA_MAX_SCALARIZATION_SIZE_SIZE;
2510
2511   /* If the user didn't set PARAM_SRA_MAX_SCALARIZATION_SIZE_<...>,
2512      fall back to a target default.  */
2513   unsigned HOST_WIDE_INT max_scalarization_size
2514     = global_options_set.x_param_values[param]
2515       ? PARAM_VALUE (param)
2516       : get_move_ratio (optimize_speed_p) * UNITS_PER_WORD;
2517
2518   max_scalarization_size *= BITS_PER_UNIT;
2519
2520   EXECUTE_IF_SET_IN_BITMAP (candidate_bitmap, 0, i, bi)
2521     if (bitmap_bit_p (should_scalarize_away_bitmap, i)
2522         && !bitmap_bit_p (cannot_scalarize_away_bitmap, i))
2523       {
2524         tree var = candidate (i);
2525
2526         if (TREE_CODE (var) == VAR_DECL
2527             && type_consists_of_records_p (TREE_TYPE (var)))
2528           {
2529             if (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (var)))
2530                 <= max_scalarization_size)
2531               {
2532                 completely_scalarize_var (var);
2533                 if (dump_file && (dump_flags & TDF_DETAILS))
2534                   {
2535                     fprintf (dump_file, "Will attempt to totally scalarize ");
2536                     print_generic_expr (dump_file, var, 0);
2537                     fprintf (dump_file, " (UID: %u): \n", DECL_UID (var));
2538                   }
2539               }
2540             else if (dump_file && (dump_flags & TDF_DETAILS))
2541               {
2542                 fprintf (dump_file, "Too big to totally scalarize: ");
2543                 print_generic_expr (dump_file, var, 0);
2544                 fprintf (dump_file, " (UID: %u)\n", DECL_UID (var));
2545               }
2546           }
2547       }
2548
2549   bitmap_copy (tmp, candidate_bitmap);
2550   EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
2551     {
2552       tree var = candidate (i);
2553       struct access *access;
2554
2555       access = sort_and_splice_var_accesses (var);
2556       if (!access || !build_access_trees (access))
2557         disqualify_candidate (var,
2558                               "No or inhibitingly overlapping accesses.");
2559     }
2560
2561   propagate_all_subaccesses ();
2562
2563   bitmap_copy (tmp, candidate_bitmap);
2564   EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
2565     {
2566       tree var = candidate (i);
2567       struct access *access = get_first_repr_for_decl (var);
2568
2569       if (analyze_access_trees (access))
2570         {
2571           res++;
2572           if (dump_file && (dump_flags & TDF_DETAILS))
2573             {
2574               fprintf (dump_file, "\nAccess trees for ");
2575               print_generic_expr (dump_file, var, 0);
2576               fprintf (dump_file, " (UID: %u): \n", DECL_UID (var));
2577               dump_access_tree (dump_file, access);
2578               fprintf (dump_file, "\n");
2579             }
2580         }
2581       else
2582         disqualify_candidate (var, "No scalar replacements to be created.");
2583     }
2584
2585   BITMAP_FREE (tmp);
2586
2587   if (res)
2588     {
2589       statistics_counter_event (cfun, "Scalarized aggregates", res);
2590       return true;
2591     }
2592   else
2593     return false;
2594 }
2595
2596 /* Generate statements copying scalar replacements of accesses within a subtree
2597    into or out of AGG.  ACCESS, all its children, siblings and their children
2598    are to be processed.  AGG is an aggregate type expression (can be a
2599    declaration but does not have to be, it can for example also be a mem_ref or
2600    a series of handled components).  TOP_OFFSET is the offset of the processed
2601    subtree which has to be subtracted from offsets of individual accesses to
2602    get corresponding offsets for AGG.  If CHUNK_SIZE is non-null, copy only
2603    replacements in the interval <start_offset, start_offset + chunk_size>,
2604    otherwise copy all.  GSI is a statement iterator used to place the new
2605    statements.  WRITE should be true when the statements should write from AGG
2606    to the replacement and false if vice versa.  if INSERT_AFTER is true, new
2607    statements will be added after the current statement in GSI, they will be
2608    added before the statement otherwise.  */
2609
2610 static void
2611 generate_subtree_copies (struct access *access, tree agg,
2612                          HOST_WIDE_INT top_offset,
2613                          HOST_WIDE_INT start_offset, HOST_WIDE_INT chunk_size,
2614                          gimple_stmt_iterator *gsi, bool write,
2615                          bool insert_after, location_t loc)
2616 {
2617   do
2618     {
2619       if (chunk_size && access->offset >= start_offset + chunk_size)
2620         return;
2621
2622       if (access->grp_to_be_replaced
2623           && (chunk_size == 0
2624               || access->offset + access->size > start_offset))
2625         {
2626           tree expr, repl = get_access_replacement (access);
2627           gassign *stmt;
2628
2629           expr = build_ref_for_model (loc, agg, access->offset - top_offset,
2630                                       access, gsi, insert_after);
2631
2632           if (write)
2633             {
2634               if (access->grp_partial_lhs)
2635                 expr = force_gimple_operand_gsi (gsi, expr, true, NULL_TREE,
2636                                                  !insert_after,
2637                                                  insert_after ? GSI_NEW_STMT
2638                                                  : GSI_SAME_STMT);
2639               stmt = gimple_build_assign (repl, expr);
2640             }
2641           else
2642             {
2643               TREE_NO_WARNING (repl) = 1;
2644               if (access->grp_partial_lhs)
2645                 repl = force_gimple_operand_gsi (gsi, repl, true, NULL_TREE,
2646                                                  !insert_after,
2647                                                  insert_after ? GSI_NEW_STMT
2648                                                  : GSI_SAME_STMT);
2649               stmt = gimple_build_assign (expr, repl);
2650             }
2651           gimple_set_location (stmt, loc);
2652
2653           if (insert_after)
2654             gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
2655           else
2656             gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
2657           update_stmt (stmt);
2658           sra_stats.subtree_copies++;
2659         }
2660       else if (write
2661                && access->grp_to_be_debug_replaced
2662                && (chunk_size == 0
2663                    || access->offset + access->size > start_offset))
2664         {
2665           gdebug *ds;
2666           tree drhs = build_debug_ref_for_model (loc, agg,
2667                                                  access->offset - top_offset,
2668                                                  access);
2669           ds = gimple_build_debug_bind (get_access_replacement (access),
2670                                         drhs, gsi_stmt (*gsi));
2671           if (insert_after)
2672             gsi_insert_after (gsi, ds, GSI_NEW_STMT);
2673           else
2674             gsi_insert_before (gsi, ds, GSI_SAME_STMT);
2675         }
2676
2677       if (access->first_child)
2678         generate_subtree_copies (access->first_child, agg, top_offset,
2679                                  start_offset, chunk_size, gsi,
2680                                  write, insert_after, loc);
2681
2682       access = access->next_sibling;
2683     }
2684   while (access);
2685 }
2686
2687 /* Assign zero to all scalar replacements in an access subtree.  ACCESS is the
2688    the root of the subtree to be processed.  GSI is the statement iterator used
2689    for inserting statements which are added after the current statement if
2690    INSERT_AFTER is true or before it otherwise.  */
2691
2692 static void
2693 init_subtree_with_zero (struct access *access, gimple_stmt_iterator *gsi,
2694                         bool insert_after, location_t loc)
2695
2696 {
2697   struct access *child;
2698
2699   if (access->grp_to_be_replaced)
2700     {
2701       gassign *stmt;
2702
2703       stmt = gimple_build_assign (get_access_replacement (access),
2704                                   build_zero_cst (access->type));
2705       if (insert_after)
2706         gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
2707       else
2708         gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
2709       update_stmt (stmt);
2710       gimple_set_location (stmt, loc);
2711     }
2712   else if (access->grp_to_be_debug_replaced)
2713     {
2714       gdebug *ds
2715         = gimple_build_debug_bind (get_access_replacement (access),
2716                                    build_zero_cst (access->type),
2717                                    gsi_stmt (*gsi));
2718       if (insert_after)
2719         gsi_insert_after (gsi, ds, GSI_NEW_STMT);
2720       else
2721         gsi_insert_before (gsi, ds, GSI_SAME_STMT);
2722     }
2723
2724   for (child = access->first_child; child; child = child->next_sibling)
2725     init_subtree_with_zero (child, gsi, insert_after, loc);
2726 }
2727
2728 /* Clobber all scalar replacements in an access subtree.  ACCESS is the the
2729    root of the subtree to be processed.  GSI is the statement iterator used
2730    for inserting statements which are added after the current statement if
2731    INSERT_AFTER is true or before it otherwise.  */
2732
2733 static void
2734 clobber_subtree (struct access *access, gimple_stmt_iterator *gsi,
2735                 bool insert_after, location_t loc)
2736
2737 {
2738   struct access *child;
2739
2740   if (access->grp_to_be_replaced)
2741     {
2742       tree rep = get_access_replacement (access);
2743       tree clobber = build_constructor (access->type, NULL);
2744       TREE_THIS_VOLATILE (clobber) = 1;
2745       gimple stmt = gimple_build_assign (rep, clobber);
2746
2747       if (insert_after)
2748         gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
2749       else
2750         gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
2751       update_stmt (stmt);
2752       gimple_set_location (stmt, loc);
2753     }
2754
2755   for (child = access->first_child; child; child = child->next_sibling)
2756     clobber_subtree (child, gsi, insert_after, loc);
2757 }
2758
2759 /* Search for an access representative for the given expression EXPR and
2760    return it or NULL if it cannot be found.  */
2761
2762 static struct access *
2763 get_access_for_expr (tree expr)
2764 {
2765   HOST_WIDE_INT offset, size, max_size;
2766   tree base;
2767
2768   /* FIXME: This should not be necessary but Ada produces V_C_Es with a type of
2769      a different size than the size of its argument and we need the latter
2770      one.  */
2771   if (TREE_CODE (expr) == VIEW_CONVERT_EXPR)
2772     expr = TREE_OPERAND (expr, 0);
2773
2774   base = get_ref_base_and_extent (expr, &offset, &size, &max_size);
2775   if (max_size == -1 || !DECL_P (base))
2776     return NULL;
2777
2778   if (!bitmap_bit_p (candidate_bitmap, DECL_UID (base)))
2779     return NULL;
2780
2781   return get_var_base_offset_size_access (base, offset, max_size);
2782 }
2783
2784 /* Replace the expression EXPR with a scalar replacement if there is one and
2785    generate other statements to do type conversion or subtree copying if
2786    necessary.  GSI is used to place newly created statements, WRITE is true if
2787    the expression is being written to (it is on a LHS of a statement or output
2788    in an assembly statement).  */
2789
2790 static bool
2791 sra_modify_expr (tree *expr, gimple_stmt_iterator *gsi, bool write)
2792 {
2793   location_t loc;
2794   struct access *access;
2795   tree type, bfr, orig_expr;
2796
2797   if (TREE_CODE (*expr) == BIT_FIELD_REF)
2798     {
2799       bfr = *expr;
2800       expr = &TREE_OPERAND (*expr, 0);
2801     }
2802   else
2803     bfr = NULL_TREE;
2804
2805   if (TREE_CODE (*expr) == REALPART_EXPR || TREE_CODE (*expr) == IMAGPART_EXPR)
2806     expr = &TREE_OPERAND (*expr, 0);
2807   access = get_access_for_expr (*expr);
2808   if (!access)
2809     return false;
2810   type = TREE_TYPE (*expr);
2811   orig_expr = *expr;
2812
2813   loc = gimple_location (gsi_stmt (*gsi));
2814   gimple_stmt_iterator alt_gsi = gsi_none ();
2815   if (write && stmt_ends_bb_p (gsi_stmt (*gsi)))
2816     {
2817       alt_gsi = gsi_start_edge (single_non_eh_succ (gsi_bb (*gsi)));
2818       gsi = &alt_gsi;
2819     }
2820
2821   if (access->grp_to_be_replaced)
2822     {
2823       tree repl = get_access_replacement (access);
2824       /* If we replace a non-register typed access simply use the original
2825          access expression to extract the scalar component afterwards.
2826          This happens if scalarizing a function return value or parameter
2827          like in gcc.c-torture/execute/20041124-1.c, 20050316-1.c and
2828          gcc.c-torture/compile/20011217-1.c.
2829
2830          We also want to use this when accessing a complex or vector which can
2831          be accessed as a different type too, potentially creating a need for
2832          type conversion (see PR42196) and when scalarized unions are involved
2833          in assembler statements (see PR42398).  */
2834       if (!useless_type_conversion_p (type, access->type))
2835         {
2836           tree ref;
2837
2838           ref = build_ref_for_model (loc, orig_expr, 0, access, gsi, false);
2839
2840           if (write)
2841             {
2842               gassign *stmt;
2843
2844               if (access->grp_partial_lhs)
2845                 ref = force_gimple_operand_gsi (gsi, ref, true, NULL_TREE,
2846                                                  false, GSI_NEW_STMT);
2847               stmt = gimple_build_assign (repl, ref);
2848               gimple_set_location (stmt, loc);
2849               gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
2850             }
2851           else
2852             {
2853               gassign *stmt;
2854
2855               if (access->grp_partial_lhs)
2856                 repl = force_gimple_operand_gsi (gsi, repl, true, NULL_TREE,
2857                                                  true, GSI_SAME_STMT);
2858               stmt = gimple_build_assign (ref, repl);
2859               gimple_set_location (stmt, loc);
2860               gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
2861             }
2862         }
2863       else
2864         *expr = repl;
2865       sra_stats.exprs++;
2866     }
2867   else if (write && access->grp_to_be_debug_replaced)
2868     {
2869       gdebug *ds = gimple_build_debug_bind (get_access_replacement (access),
2870                                             NULL_TREE,
2871                                             gsi_stmt (*gsi));
2872       gsi_insert_after (gsi, ds, GSI_NEW_STMT);
2873     }
2874
2875   if (access->first_child)
2876     {
2877       HOST_WIDE_INT start_offset, chunk_size;
2878       if (bfr
2879           && tree_fits_uhwi_p (TREE_OPERAND (bfr, 1))
2880           && tree_fits_uhwi_p (TREE_OPERAND (bfr, 2)))
2881         {
2882           chunk_size = tree_to_uhwi (TREE_OPERAND (bfr, 1));
2883           start_offset = access->offset
2884             + tree_to_uhwi (TREE_OPERAND (bfr, 2));
2885         }
2886       else
2887         start_offset = chunk_size = 0;
2888
2889       generate_subtree_copies (access->first_child, orig_expr, access->offset,
2890                                start_offset, chunk_size, gsi, write, write,
2891                                loc);
2892     }
2893   return true;
2894 }
2895
2896 /* Where scalar replacements of the RHS have been written to when a replacement
2897    of a LHS of an assigments cannot be direclty loaded from a replacement of
2898    the RHS. */
2899 enum unscalarized_data_handling { SRA_UDH_NONE,  /* Nothing done so far. */
2900                                   SRA_UDH_RIGHT, /* Data flushed to the RHS. */
2901                                   SRA_UDH_LEFT }; /* Data flushed to the LHS. */
2902
2903 struct subreplacement_assignment_data
2904 {
2905   /* Offset of the access representing the lhs of the assignment.  */
2906   HOST_WIDE_INT left_offset;
2907
2908   /* LHS and RHS of the original assignment.  */
2909   tree assignment_lhs, assignment_rhs;
2910
2911   /* Access representing the rhs of the whole assignment.  */
2912   struct access *top_racc;
2913
2914   /* Stmt iterator used for statement insertions after the original assignment.
2915    It points to the main GSI used to traverse a BB during function body
2916    modification.  */
2917   gimple_stmt_iterator *new_gsi;
2918
2919   /* Stmt iterator used for statement insertions before the original
2920    assignment.  Keeps on pointing to the original statement.  */
2921   gimple_stmt_iterator old_gsi;
2922
2923   /* Location of the assignment.   */
2924   location_t loc;
2925
2926   /* Keeps the information whether we have needed to refresh replacements of
2927    the LHS and from which side of the assignments this takes place.  */
2928   enum unscalarized_data_handling refreshed;
2929 };
2930
2931 /* Store all replacements in the access tree rooted in TOP_RACC either to their
2932    base aggregate if there are unscalarized data or directly to LHS of the
2933    statement that is pointed to by GSI otherwise.  */
2934
2935 static void
2936 handle_unscalarized_data_in_subtree (struct subreplacement_assignment_data *sad)
2937 {
2938   tree src;
2939   if (sad->top_racc->grp_unscalarized_data)
2940     {
2941       src = sad->assignment_rhs;
2942       sad->refreshed = SRA_UDH_RIGHT;
2943     }
2944   else
2945     {
2946       src = sad->assignment_lhs;
2947       sad->refreshed = SRA_UDH_LEFT;
2948     }
2949   generate_subtree_copies (sad->top_racc->first_child, src,
2950                            sad->top_racc->offset, 0, 0,
2951                            &sad->old_gsi, false, false, sad->loc);
2952 }
2953
2954 /* Try to generate statements to load all sub-replacements in an access subtree
2955    formed by children of LACC from scalar replacements in the SAD->top_racc
2956    subtree.  If that is not possible, refresh the SAD->top_racc base aggregate
2957    and load the accesses from it.  */
2958
2959 static void
2960 load_assign_lhs_subreplacements (struct access *lacc,
2961                                  struct subreplacement_assignment_data *sad)
2962 {
2963   for (lacc = lacc->first_child; lacc; lacc = lacc->next_sibling)
2964     {
2965       HOST_WIDE_INT offset;
2966       offset = lacc->offset - sad->left_offset + sad->top_racc->offset;
2967
2968       if (lacc->grp_to_be_replaced)
2969         {
2970           struct access *racc;
2971           gassign *stmt;
2972           tree rhs;
2973
2974           racc = find_access_in_subtree (sad->top_racc, offset, lacc->size);
2975           if (racc && racc->grp_to_be_replaced)
2976             {
2977               rhs = get_access_replacement (racc);
2978               if (!useless_type_conversion_p (lacc->type, racc->type))
2979                 rhs = fold_build1_loc (sad->loc, VIEW_CONVERT_EXPR,
2980                                        lacc->type, rhs);
2981
2982               if (racc->grp_partial_lhs && lacc->grp_partial_lhs)
2983                 rhs = force_gimple_operand_gsi (&sad->old_gsi, rhs, true,
2984                                                 NULL_TREE, true, GSI_SAME_STMT);
2985             }
2986           else
2987             {
2988               /* No suitable access on the right hand side, need to load from
2989                  the aggregate.  See if we have to update it first... */
2990               if (sad->refreshed == SRA_UDH_NONE)
2991                 handle_unscalarized_data_in_subtree (sad);
2992
2993               if (sad->refreshed == SRA_UDH_LEFT)
2994                 rhs = build_ref_for_model (sad->loc, sad->assignment_lhs,
2995                                            lacc->offset - sad->left_offset,
2996                                            lacc, sad->new_gsi, true);
2997               else
2998                 rhs = build_ref_for_model (sad->loc, sad->assignment_rhs,
2999                                            lacc->offset - sad->left_offset,
3000                                            lacc, sad->new_gsi, true);
3001               if (lacc->grp_partial_lhs)
3002                 rhs = force_gimple_operand_gsi (sad->new_gsi,
3003                                                 rhs, true, NULL_TREE,
3004                                                 false, GSI_NEW_STMT);
3005             }
3006
3007           stmt = gimple_build_assign (get_access_replacement (lacc), rhs);
3008           gsi_insert_after (sad->new_gsi, stmt, GSI_NEW_STMT);
3009           gimple_set_location (stmt, sad->loc);
3010           update_stmt (stmt);
3011           sra_stats.subreplacements++;
3012         }
3013       else
3014         {
3015           if (sad->refreshed == SRA_UDH_NONE
3016               && lacc->grp_read && !lacc->grp_covered)
3017             handle_unscalarized_data_in_subtree (sad);
3018
3019           if (lacc && lacc->grp_to_be_debug_replaced)
3020             {
3021               gdebug *ds;
3022               tree drhs;
3023               struct access *racc = find_access_in_subtree (sad->top_racc,
3024                                                             offset,
3025                                                             lacc->size);
3026
3027               if (racc && racc->grp_to_be_replaced)
3028                 {
3029                   if (racc->grp_write)
3030                     drhs = get_access_replacement (racc);
3031                   else
3032                     drhs = NULL;
3033                 }
3034               else if (sad->refreshed == SRA_UDH_LEFT)
3035                 drhs = build_debug_ref_for_model (sad->loc, lacc->base,
3036                                                   lacc->offset, lacc);
3037               else if (sad->refreshed == SRA_UDH_RIGHT)
3038                 drhs = build_debug_ref_for_model (sad->loc, sad->top_racc->base,
3039                                                   offset, lacc);
3040               else
3041                 drhs = NULL_TREE;
3042               if (drhs
3043                   && !useless_type_conversion_p (lacc->type, TREE_TYPE (drhs)))
3044                 drhs = fold_build1_loc (sad->loc, VIEW_CONVERT_EXPR,
3045                                         lacc->type, drhs);
3046               ds = gimple_build_debug_bind (get_access_replacement (lacc),
3047                                             drhs, gsi_stmt (sad->old_gsi));
3048               gsi_insert_after (sad->new_gsi, ds, GSI_NEW_STMT);
3049             }
3050         }
3051
3052       if (lacc->first_child)
3053         load_assign_lhs_subreplacements (lacc, sad);
3054     }
3055 }
3056
3057 /* Result code for SRA assignment modification.  */
3058 enum assignment_mod_result { SRA_AM_NONE,       /* nothing done for the stmt */
3059                              SRA_AM_MODIFIED,  /* stmt changed but not
3060                                                   removed */
3061                              SRA_AM_REMOVED };  /* stmt eliminated */
3062
3063 /* Modify assignments with a CONSTRUCTOR on their RHS.  STMT contains a pointer
3064    to the assignment and GSI is the statement iterator pointing at it.  Returns
3065    the same values as sra_modify_assign.  */
3066
3067 static enum assignment_mod_result
3068 sra_modify_constructor_assign (gimple stmt, gimple_stmt_iterator *gsi)
3069 {
3070   tree lhs = gimple_assign_lhs (stmt);
3071   struct access *acc = get_access_for_expr (lhs);
3072   if (!acc)
3073     return SRA_AM_NONE;
3074   location_t loc = gimple_location (stmt);
3075
3076   if (gimple_clobber_p (stmt))
3077     {
3078       /* Clobber the replacement variable.  */
3079       clobber_subtree (acc, gsi, !acc->grp_covered, loc);
3080       /* Remove clobbers of fully scalarized variables, they are dead.  */
3081       if (acc->grp_covered)
3082         {
3083           unlink_stmt_vdef (stmt);
3084           gsi_remove (gsi, true);
3085           release_defs (stmt);
3086           return SRA_AM_REMOVED;
3087         }
3088       else
3089         return SRA_AM_MODIFIED;
3090     }
3091
3092   if (vec_safe_length (CONSTRUCTOR_ELTS (gimple_assign_rhs1 (stmt))) > 0)
3093     {
3094       /* I have never seen this code path trigger but if it can happen the
3095          following should handle it gracefully.  */
3096       if (access_has_children_p (acc))
3097         generate_subtree_copies (acc->first_child, lhs, acc->offset, 0, 0, gsi,
3098                                  true, true, loc);
3099       return SRA_AM_MODIFIED;
3100     }
3101
3102   if (acc->grp_covered)
3103     {
3104       init_subtree_with_zero (acc, gsi, false, loc);
3105       unlink_stmt_vdef (stmt);
3106       gsi_remove (gsi, true);
3107       release_defs (stmt);
3108       return SRA_AM_REMOVED;
3109     }
3110   else
3111     {
3112       init_subtree_with_zero (acc, gsi, true, loc);
3113       return SRA_AM_MODIFIED;
3114     }
3115 }
3116
3117 /* Create and return a new suitable default definition SSA_NAME for RACC which
3118    is an access describing an uninitialized part of an aggregate that is being
3119    loaded.  */
3120
3121 static tree
3122 get_repl_default_def_ssa_name (struct access *racc)
3123 {
3124   gcc_checking_assert (!racc->grp_to_be_replaced
3125                        && !racc->grp_to_be_debug_replaced);
3126   if (!racc->replacement_decl)
3127     racc->replacement_decl = create_access_replacement (racc);
3128   return get_or_create_ssa_default_def (cfun, racc->replacement_decl);
3129 }
3130
3131 /* Return true if REF has an VIEW_CONVERT_EXPR or a COMPONENT_REF with a
3132    bit-field field declaration somewhere in it.  */
3133
3134 static inline bool
3135 contains_vce_or_bfcref_p (const_tree ref)
3136 {
3137   while (handled_component_p (ref))
3138     {
3139       if (TREE_CODE (ref) == VIEW_CONVERT_EXPR
3140           || (TREE_CODE (ref) == COMPONENT_REF
3141               && DECL_BIT_FIELD (TREE_OPERAND (ref, 1))))
3142         return true;
3143       ref = TREE_OPERAND (ref, 0);
3144     }
3145
3146   return false;
3147 }
3148
3149 /* Examine both sides of the assignment statement pointed to by STMT, replace
3150    them with a scalare replacement if there is one and generate copying of
3151    replacements if scalarized aggregates have been used in the assignment.  GSI
3152    is used to hold generated statements for type conversions and subtree
3153    copying.  */
3154
3155 static enum assignment_mod_result
3156 sra_modify_assign (gimple stmt, gimple_stmt_iterator *gsi)
3157 {
3158   struct access *lacc, *racc;
3159   tree lhs, rhs;
3160   bool modify_this_stmt = false;
3161   bool force_gimple_rhs = false;
3162   location_t loc;
3163   gimple_stmt_iterator orig_gsi = *gsi;
3164
3165   if (!gimple_assign_single_p (stmt))
3166     return SRA_AM_NONE;
3167   lhs = gimple_assign_lhs (stmt);
3168   rhs = gimple_assign_rhs1 (stmt);
3169
3170   if (TREE_CODE (rhs) == CONSTRUCTOR)
3171     return sra_modify_constructor_assign (stmt, gsi);
3172
3173   if (TREE_CODE (rhs) == REALPART_EXPR || TREE_CODE (lhs) == REALPART_EXPR
3174       || TREE_CODE (rhs) == IMAGPART_EXPR || TREE_CODE (lhs) == IMAGPART_EXPR
3175       || TREE_CODE (rhs) == BIT_FIELD_REF || TREE_CODE (lhs) == BIT_FIELD_REF)
3176     {
3177       modify_this_stmt = sra_modify_expr (gimple_assign_rhs1_ptr (stmt),
3178                                           gsi, false);
3179       modify_this_stmt |= sra_modify_expr (gimple_assign_lhs_ptr (stmt),
3180                                            gsi, true);
3181       return modify_this_stmt ? SRA_AM_MODIFIED : SRA_AM_NONE;
3182     }
3183
3184   lacc = get_access_for_expr (lhs);
3185   racc = get_access_for_expr (rhs);
3186   if (!lacc && !racc)
3187     return SRA_AM_NONE;
3188
3189   loc = gimple_location (stmt);
3190   if (lacc && lacc->grp_to_be_replaced)
3191     {
3192       lhs = get_access_replacement (lacc);
3193       gimple_assign_set_lhs (stmt, lhs);
3194       modify_this_stmt = true;
3195       if (lacc->grp_partial_lhs)
3196         force_gimple_rhs = true;
3197       sra_stats.exprs++;
3198     }
3199
3200   if (racc && racc->grp_to_be_replaced)
3201     {
3202       rhs = get_access_replacement (racc);
3203       modify_this_stmt = true;
3204       if (racc->grp_partial_lhs)
3205         force_gimple_rhs = true;
3206       sra_stats.exprs++;
3207     }
3208   else if (racc
3209            && !racc->grp_unscalarized_data
3210            && TREE_CODE (lhs) == SSA_NAME
3211            && !access_has_replacements_p (racc))
3212     {
3213       rhs = get_repl_default_def_ssa_name (racc);
3214       modify_this_stmt = true;
3215       sra_stats.exprs++;
3216     }
3217
3218   if (modify_this_stmt)
3219     {
3220       if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
3221         {
3222           /* If we can avoid creating a VIEW_CONVERT_EXPR do so.
3223              ???  This should move to fold_stmt which we simply should
3224              call after building a VIEW_CONVERT_EXPR here.  */
3225           if (AGGREGATE_TYPE_P (TREE_TYPE (lhs))
3226               && !contains_bitfld_component_ref_p (lhs))
3227             {
3228               lhs = build_ref_for_model (loc, lhs, 0, racc, gsi, false);
3229               gimple_assign_set_lhs (stmt, lhs);
3230             }
3231           else if (AGGREGATE_TYPE_P (TREE_TYPE (rhs))
3232                    && !contains_vce_or_bfcref_p (rhs))
3233             rhs = build_ref_for_model (loc, rhs, 0, lacc, gsi, false);
3234
3235           if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
3236             {
3237               rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
3238                                      rhs);
3239               if (is_gimple_reg_type (TREE_TYPE (lhs))
3240                   && TREE_CODE (lhs) != SSA_NAME)
3241                 force_gimple_rhs = true;
3242             }
3243         }
3244     }
3245
3246   if (lacc && lacc->grp_to_be_debug_replaced)
3247     {
3248       tree dlhs = get_access_replacement (lacc);
3249       tree drhs = unshare_expr (rhs);
3250       if (!useless_type_conversion_p (TREE_TYPE (dlhs), TREE_TYPE (drhs)))
3251         {
3252           if (AGGREGATE_TYPE_P (TREE_TYPE (drhs))
3253               && !contains_vce_or_bfcref_p (drhs))
3254             drhs = build_debug_ref_for_model (loc, drhs, 0, lacc);
3255           if (drhs
3256               && !useless_type_conversion_p (TREE_TYPE (dlhs),
3257                                              TREE_TYPE (drhs)))
3258             drhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR,
3259                                     TREE_TYPE (dlhs), drhs);
3260         }
3261       gdebug *ds = gimple_build_debug_bind (dlhs, drhs, stmt);
3262       gsi_insert_before (gsi, ds, GSI_SAME_STMT);
3263     }
3264
3265   /* From this point on, the function deals with assignments in between
3266      aggregates when at least one has scalar reductions of some of its
3267      components.  There are three possible scenarios: Both the LHS and RHS have
3268      to-be-scalarized components, 2) only the RHS has or 3) only the LHS has.
3269
3270      In the first case, we would like to load the LHS components from RHS
3271      components whenever possible.  If that is not possible, we would like to
3272      read it directly from the RHS (after updating it by storing in it its own
3273      components).  If there are some necessary unscalarized data in the LHS,
3274      those will be loaded by the original assignment too.  If neither of these
3275      cases happen, the original statement can be removed.  Most of this is done
3276      by load_assign_lhs_subreplacements.
3277
3278      In the second case, we would like to store all RHS scalarized components
3279      directly into LHS and if they cover the aggregate completely, remove the
3280      statement too.  In the third case, we want the LHS components to be loaded
3281      directly from the RHS (DSE will remove the original statement if it
3282      becomes redundant).
3283
3284      This is a bit complex but manageable when types match and when unions do
3285      not cause confusion in a way that we cannot really load a component of LHS
3286      from the RHS or vice versa (the access representing this level can have
3287      subaccesses that are accessible only through a different union field at a
3288      higher level - different from the one used in the examined expression).
3289      Unions are fun.
3290
3291      Therefore, I specially handle a fourth case, happening when there is a
3292      specific type cast or it is impossible to locate a scalarized subaccess on
3293      the other side of the expression.  If that happens, I simply "refresh" the
3294      RHS by storing in it is scalarized components leave the original statement
3295      there to do the copying and then load the scalar replacements of the LHS.
3296      This is what the first branch does.  */
3297
3298   if (modify_this_stmt
3299       || gimple_has_volatile_ops (stmt)
3300       || contains_vce_or_bfcref_p (rhs)
3301       || contains_vce_or_bfcref_p (lhs)
3302       || stmt_ends_bb_p (stmt))
3303     {
3304       if (access_has_children_p (racc))
3305         generate_subtree_copies (racc->first_child, rhs, racc->offset, 0, 0,
3306                                  gsi, false, false, loc);
3307       if (access_has_children_p (lacc))
3308         {
3309           gimple_stmt_iterator alt_gsi = gsi_none ();
3310           if (stmt_ends_bb_p (stmt))
3311             {
3312               alt_gsi = gsi_start_edge (single_non_eh_succ (gsi_bb (*gsi)));
3313               gsi = &alt_gsi;
3314             }
3315           generate_subtree_copies (lacc->first_child, lhs, lacc->offset, 0, 0,
3316                                    gsi, true, true, loc);
3317         }
3318       sra_stats.separate_lhs_rhs_handling++;
3319
3320       /* This gimplification must be done after generate_subtree_copies,
3321          lest we insert the subtree copies in the middle of the gimplified
3322          sequence.  */
3323       if (force_gimple_rhs)
3324         rhs = force_gimple_operand_gsi (&orig_gsi, rhs, true, NULL_TREE,
3325                                         true, GSI_SAME_STMT);
3326       if (gimple_assign_rhs1 (stmt) != rhs)
3327         {
3328           modify_this_stmt = true;
3329           gimple_assign_set_rhs_from_tree (&orig_gsi, rhs);
3330           gcc_assert (stmt == gsi_stmt (orig_gsi));
3331         }
3332
3333       return modify_this_stmt ? SRA_AM_MODIFIED : SRA_AM_NONE;
3334     }
3335   else
3336     {
3337       if (access_has_children_p (lacc)
3338           && access_has_children_p (racc)
3339           /* When an access represents an unscalarizable region, it usually
3340              represents accesses with variable offset and thus must not be used
3341              to generate new memory accesses.  */
3342           && !lacc->grp_unscalarizable_region
3343           && !racc->grp_unscalarizable_region)
3344         {
3345           struct subreplacement_assignment_data sad;
3346
3347           sad.left_offset = lacc->offset;
3348           sad.assignment_lhs = lhs;
3349           sad.assignment_rhs = rhs;
3350           sad.top_racc = racc;
3351           sad.old_gsi = *gsi;
3352           sad.new_gsi = gsi;
3353           sad.loc = gimple_location (stmt);
3354           sad.refreshed = SRA_UDH_NONE;
3355
3356           if (lacc->grp_read && !lacc->grp_covered)
3357             handle_unscalarized_data_in_subtree (&sad);
3358
3359           load_assign_lhs_subreplacements (lacc, &sad);
3360           if (sad.refreshed != SRA_UDH_RIGHT)
3361             {
3362               gsi_next (gsi);
3363               unlink_stmt_vdef (stmt);
3364               gsi_remove (&sad.old_gsi, true);
3365               release_defs (stmt);
3366               sra_stats.deleted++;
3367               return SRA_AM_REMOVED;
3368             }
3369         }
3370       else
3371         {
3372           if (access_has_children_p (racc)
3373               && !racc->grp_unscalarized_data)
3374             {
3375               if (dump_file)
3376                 {
3377                   fprintf (dump_file, "Removing load: ");
3378                   print_gimple_stmt (dump_file, stmt, 0, 0);
3379                 }
3380               generate_subtree_copies (racc->first_child, lhs,
3381                                        racc->offset, 0, 0, gsi,
3382                                        false, false, loc);
3383               gcc_assert (stmt == gsi_stmt (*gsi));
3384               unlink_stmt_vdef (stmt);
3385               gsi_remove (gsi, true);
3386               release_defs (stmt);
3387               sra_stats.deleted++;
3388               return SRA_AM_REMOVED;
3389             }
3390           /* Restore the aggregate RHS from its components so the
3391              prevailing aggregate copy does the right thing.  */
3392           if (access_has_children_p (racc))
3393             generate_subtree_copies (racc->first_child, rhs, racc->offset, 0, 0,
3394                                      gsi, false, false, loc);
3395           /* Re-load the components of the aggregate copy destination.
3396              But use the RHS aggregate to load from to expose more
3397              optimization opportunities.  */
3398           if (access_has_children_p (lacc))
3399             generate_subtree_copies (lacc->first_child, rhs, lacc->offset,
3400                                      0, 0, gsi, true, true, loc);
3401         }
3402
3403       return SRA_AM_NONE;
3404     }
3405 }
3406
3407 /* Traverse the function body and all modifications as decided in
3408    analyze_all_variable_accesses.  Return true iff the CFG has been
3409    changed.  */
3410
3411 static bool
3412 sra_modify_function_body (void)
3413 {
3414   bool cfg_changed = false;
3415   basic_block bb;
3416
3417   FOR_EACH_BB_FN (bb, cfun)
3418     {
3419       gimple_stmt_iterator gsi = gsi_start_bb (bb);
3420       while (!gsi_end_p (gsi))
3421         {
3422           gimple stmt = gsi_stmt (gsi);
3423           enum assignment_mod_result assign_result;
3424           bool modified = false, deleted = false;
3425           tree *t;
3426           unsigned i;
3427
3428           switch (gimple_code (stmt))
3429             {
3430             case GIMPLE_RETURN:
3431               t = gimple_return_retval_ptr (as_a <greturn *> (stmt));
3432               if (*t != NULL_TREE)
3433                 modified |= sra_modify_expr (t, &gsi, false);
3434               break;
3435
3436             case GIMPLE_ASSIGN:
3437               assign_result = sra_modify_assign (stmt, &gsi);
3438               modified |= assign_result == SRA_AM_MODIFIED;
3439               deleted = assign_result == SRA_AM_REMOVED;
3440               break;
3441
3442             case GIMPLE_CALL:
3443               /* Operands must be processed before the lhs.  */
3444               for (i = 0; i < gimple_call_num_args (stmt); i++)
3445                 {
3446                   t = gimple_call_arg_ptr (stmt, i);
3447                   modified |= sra_modify_expr (t, &gsi, false);
3448                 }
3449
3450               if (gimple_call_lhs (stmt))
3451                 {
3452                   t = gimple_call_lhs_ptr (stmt);
3453                   modified |= sra_modify_expr (t, &gsi, true);
3454                 }
3455               break;
3456
3457             case GIMPLE_ASM:
3458               {
3459                 gasm *asm_stmt = as_a <gasm *> (stmt);
3460                 for (i = 0; i < gimple_asm_ninputs (asm_stmt); i++)
3461                   {
3462                     t = &TREE_VALUE (gimple_asm_input_op (asm_stmt, i));
3463                     modified |= sra_modify_expr (t, &gsi, false);
3464                   }
3465                 for (i = 0; i < gimple_asm_noutputs (asm_stmt); i++)
3466                   {
3467                     t = &TREE_VALUE (gimple_asm_output_op (asm_stmt, i));
3468                     modified |= sra_modify_expr (t, &gsi, true);
3469                   }
3470               }
3471               break;
3472
3473             default:
3474               break;
3475             }
3476
3477           if (modified)
3478             {
3479               update_stmt (stmt);
3480               if (maybe_clean_eh_stmt (stmt)
3481                   && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
3482                 cfg_changed = true;
3483             }
3484           if (!deleted)
3485             gsi_next (&gsi);
3486         }
3487     }
3488
3489   gsi_commit_edge_inserts ();
3490   return cfg_changed;
3491 }
3492
3493 /* Generate statements initializing scalar replacements of parts of function
3494    parameters.  */
3495
3496 static void
3497 initialize_parameter_reductions (void)
3498 {
3499   gimple_stmt_iterator gsi;
3500   gimple_seq seq = NULL;
3501   tree parm;
3502
3503   gsi = gsi_start (seq);
3504   for (parm = DECL_ARGUMENTS (current_function_decl);
3505        parm;
3506        parm = DECL_CHAIN (parm))
3507     {
3508       vec<access_p> *access_vec;
3509       struct access *access;
3510
3511       if (!bitmap_bit_p (candidate_bitmap, DECL_UID (parm)))
3512         continue;
3513       access_vec = get_base_access_vector (parm);
3514       if (!access_vec)
3515         continue;
3516
3517       for (access = (*access_vec)[0];
3518            access;
3519            access = access->next_grp)
3520         generate_subtree_copies (access, parm, 0, 0, 0, &gsi, true, true,
3521                                  EXPR_LOCATION (parm));
3522     }
3523
3524   seq = gsi_seq (gsi);
3525   if (seq)
3526     gsi_insert_seq_on_edge_immediate (single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)), seq);
3527 }
3528
3529 /* The "main" function of intraprocedural SRA passes.  Runs the analysis and if
3530    it reveals there are components of some aggregates to be scalarized, it runs
3531    the required transformations.  */
3532 static unsigned int
3533 perform_intra_sra (void)
3534 {
3535   int ret = 0;
3536   sra_initialize ();
3537
3538   if (!find_var_candidates ())
3539     goto out;
3540
3541   if (!scan_function ())
3542     goto out;
3543
3544   if (!analyze_all_variable_accesses ())
3545     goto out;
3546
3547   if (sra_modify_function_body ())
3548     ret = TODO_update_ssa | TODO_cleanup_cfg;
3549   else
3550     ret = TODO_update_ssa;
3551   initialize_parameter_reductions ();
3552
3553   statistics_counter_event (cfun, "Scalar replacements created",
3554                             sra_stats.replacements);
3555   statistics_counter_event (cfun, "Modified expressions", sra_stats.exprs);
3556   statistics_counter_event (cfun, "Subtree copy stmts",
3557                             sra_stats.subtree_copies);
3558   statistics_counter_event (cfun, "Subreplacement stmts",
3559                             sra_stats.subreplacements);
3560   statistics_counter_event (cfun, "Deleted stmts", sra_stats.deleted);
3561   statistics_counter_event (cfun, "Separate LHS and RHS handling",
3562                             sra_stats.separate_lhs_rhs_handling);
3563
3564  out:
3565   sra_deinitialize ();
3566   return ret;
3567 }
3568
3569 /* Perform early intraprocedural SRA.  */
3570 static unsigned int
3571 early_intra_sra (void)
3572 {
3573   sra_mode = SRA_MODE_EARLY_INTRA;
3574   return perform_intra_sra ();
3575 }
3576
3577 /* Perform "late" intraprocedural SRA.  */
3578 static unsigned int
3579 late_intra_sra (void)
3580 {
3581   sra_mode = SRA_MODE_INTRA;
3582   return perform_intra_sra ();
3583 }
3584
3585
3586 static bool
3587 gate_intra_sra (void)
3588 {
3589   return flag_tree_sra != 0 && dbg_cnt (tree_sra);
3590 }
3591
3592
3593 namespace {
3594
3595 const pass_data pass_data_sra_early =
3596 {
3597   GIMPLE_PASS, /* type */
3598   "esra", /* name */
3599   OPTGROUP_NONE, /* optinfo_flags */
3600   TV_TREE_SRA, /* tv_id */
3601   ( PROP_cfg | PROP_ssa ), /* properties_required */
3602   0, /* properties_provided */
3603   0, /* properties_destroyed */
3604   0, /* todo_flags_start */
3605   TODO_update_ssa, /* todo_flags_finish */
3606 };
3607
3608 class pass_sra_early : public gimple_opt_pass
3609 {
3610 public:
3611   pass_sra_early (gcc::context *ctxt)
3612     : gimple_opt_pass (pass_data_sra_early, ctxt)
3613   {}
3614
3615   /* opt_pass methods: */
3616   virtual bool gate (function *) { return gate_intra_sra (); }
3617   virtual unsigned int execute (function *) { return early_intra_sra (); }
3618
3619 }; // class pass_sra_early
3620
3621 } // anon namespace
3622
3623 gimple_opt_pass *
3624 make_pass_sra_early (gcc::context *ctxt)
3625 {
3626   return new pass_sra_early (ctxt);
3627 }
3628
3629 namespace {
3630
3631 const pass_data pass_data_sra =
3632 {
3633   GIMPLE_PASS, /* type */
3634   "sra", /* name */
3635   OPTGROUP_NONE, /* optinfo_flags */
3636   TV_TREE_SRA, /* tv_id */
3637   ( PROP_cfg | PROP_ssa ), /* properties_required */
3638   0, /* properties_provided */
3639   0, /* properties_destroyed */
3640   TODO_update_address_taken, /* todo_flags_start */
3641   TODO_update_ssa, /* todo_flags_finish */
3642 };
3643
3644 class pass_sra : public gimple_opt_pass
3645 {
3646 public:
3647   pass_sra (gcc::context *ctxt)
3648     : gimple_opt_pass (pass_data_sra, ctxt)
3649   {}
3650
3651   /* opt_pass methods: */
3652   virtual bool gate (function *) { return gate_intra_sra (); }
3653   virtual unsigned int execute (function *) { return late_intra_sra (); }
3654
3655 }; // class pass_sra
3656
3657 } // anon namespace
3658
3659 gimple_opt_pass *
3660 make_pass_sra (gcc::context *ctxt)
3661 {
3662   return new pass_sra (ctxt);
3663 }
3664
3665
3666 /* Return true iff PARM (which must be a parm_decl) is an unused scalar
3667    parameter.  */
3668
3669 static bool
3670 is_unused_scalar_param (tree parm)
3671 {
3672   tree name;
3673   return (is_gimple_reg (parm)
3674           && (!(name = ssa_default_def (cfun, parm))
3675               || has_zero_uses (name)));
3676 }
3677
3678 /* Scan immediate uses of a default definition SSA name of a parameter PARM and
3679    examine whether there are any direct or otherwise infeasible ones.  If so,
3680    return true, otherwise return false.  PARM must be a gimple register with a
3681    non-NULL default definition.  */
3682
3683 static bool
3684 ptr_parm_has_direct_uses (tree parm)
3685 {
3686   imm_use_iterator ui;
3687   gimple stmt;
3688   tree name = ssa_default_def (cfun, parm);
3689   bool ret = false;
3690
3691   FOR_EACH_IMM_USE_STMT (stmt, ui, name)
3692     {
3693       int uses_ok = 0;
3694       use_operand_p use_p;
3695
3696       if (is_gimple_debug (stmt))
3697         continue;
3698
3699       /* Valid uses include dereferences on the lhs and the rhs.  */
3700       if (gimple_has_lhs (stmt))
3701         {
3702           tree lhs = gimple_get_lhs (stmt);
3703           while (handled_component_p (lhs))
3704             lhs = TREE_OPERAND (lhs, 0);
3705           if (TREE_CODE (lhs) == MEM_REF
3706               && TREE_OPERAND (lhs, 0) == name
3707               && integer_zerop (TREE_OPERAND (lhs, 1))
3708               && types_compatible_p (TREE_TYPE (lhs),
3709                                      TREE_TYPE (TREE_TYPE (name)))
3710               && !TREE_THIS_VOLATILE (lhs))
3711             uses_ok++;
3712         }
3713       if (gimple_assign_single_p (stmt))
3714         {
3715           tree rhs = gimple_assign_rhs1 (stmt);
3716           while (handled_component_p (rhs))
3717             rhs = TREE_OPERAND (rhs, 0);
3718           if (TREE_CODE (rhs) == MEM_REF
3719               && TREE_OPERAND (rhs, 0) == name
3720               && integer_zerop (TREE_OPERAND (rhs, 1))
3721               && types_compatible_p (TREE_TYPE (rhs),
3722                                      TREE_TYPE (TREE_TYPE (name)))
3723               && !TREE_THIS_VOLATILE (rhs))
3724             uses_ok++;
3725         }
3726       else if (is_gimple_call (stmt))
3727         {
3728           unsigned i;
3729           for (i = 0; i < gimple_call_num_args (stmt); ++i)
3730             {
3731               tree arg = gimple_call_arg (stmt, i);
3732               while (handled_component_p (arg))
3733                 arg = TREE_OPERAND (arg, 0);
3734               if (TREE_CODE (arg) == MEM_REF
3735                   && TREE_OPERAND (arg, 0) == name
3736                   && integer_zerop (TREE_OPERAND (arg, 1))
3737                   && types_compatible_p (TREE_TYPE (arg),
3738                                          TREE_TYPE (TREE_TYPE (name)))
3739                   && !TREE_THIS_VOLATILE (arg))
3740                 uses_ok++;
3741             }
3742         }
3743
3744       /* If the number of valid uses does not match the number of
3745          uses in this stmt there is an unhandled use.  */
3746       FOR_EACH_IMM_USE_ON_STMT (use_p, ui)
3747         --uses_ok;
3748
3749       if (uses_ok != 0)
3750         ret = true;
3751
3752       if (ret)
3753         BREAK_FROM_IMM_USE_STMT (ui);
3754     }
3755
3756   return ret;
3757 }
3758
3759 /* Identify candidates for reduction for IPA-SRA based on their type and mark
3760    them in candidate_bitmap.  Note that these do not necessarily include
3761    parameter which are unused and thus can be removed.  Return true iff any
3762    such candidate has been found.  */
3763
3764 static bool
3765 find_param_candidates (void)
3766 {
3767   tree parm;
3768   int count = 0;
3769   bool ret = false;
3770   const char *msg;
3771
3772   for (parm = DECL_ARGUMENTS (current_function_decl);
3773        parm;
3774        parm = DECL_CHAIN (parm))
3775     {
3776       tree type = TREE_TYPE (parm);
3777       tree_node **slot;
3778
3779       count++;
3780
3781       if (TREE_THIS_VOLATILE (parm)
3782           || TREE_ADDRESSABLE (parm)
3783           || (!is_gimple_reg_type (type) && is_va_list_type (type)))
3784         continue;
3785
3786       if (is_unused_scalar_param (parm))
3787         {
3788           ret = true;
3789           continue;
3790         }
3791
3792       if (POINTER_TYPE_P (type))
3793         {
3794           type = TREE_TYPE (type);
3795
3796           if (TREE_CODE (type) == FUNCTION_TYPE
3797               || TYPE_VOLATILE (type)
3798               || (TREE_CODE (type) == ARRAY_TYPE
3799                   && TYPE_NONALIASED_COMPONENT (type))
3800               || !is_gimple_reg (parm)
3801               || is_va_list_type (type)
3802               || ptr_parm_has_direct_uses (parm))
3803             continue;
3804         }
3805       else if (!AGGREGATE_TYPE_P (type))
3806         continue;
3807
3808       if (!COMPLETE_TYPE_P (type)
3809           || !tree_fits_uhwi_p (TYPE_SIZE (type))
3810           || tree_to_uhwi (TYPE_SIZE (type)) == 0
3811           || (AGGREGATE_TYPE_P (type)
3812               && type_internals_preclude_sra_p (type, &msg)))
3813         continue;
3814
3815       bitmap_set_bit (candidate_bitmap, DECL_UID (parm));
3816       slot = candidates->find_slot_with_hash (parm, DECL_UID (parm), INSERT);
3817       *slot = parm;
3818
3819       ret = true;
3820       if (dump_file && (dump_flags & TDF_DETAILS))
3821         {
3822           fprintf (dump_file, "Candidate (%d): ", DECL_UID (parm));
3823           print_generic_expr (dump_file, parm, 0);
3824           fprintf (dump_file, "\n");
3825         }
3826     }
3827
3828   func_param_count = count;
3829   return ret;
3830 }
3831
3832 /* Callback of walk_aliased_vdefs, marks the access passed as DATA as
3833    maybe_modified. */
3834
3835 static bool
3836 mark_maybe_modified (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef ATTRIBUTE_UNUSED,
3837                      void *data)
3838 {
3839   struct access *repr = (struct access *) data;
3840
3841   repr->grp_maybe_modified = 1;
3842   return true;
3843 }
3844
3845 /* Analyze what representatives (in linked lists accessible from
3846    REPRESENTATIVES) can be modified by side effects of statements in the
3847    current function.  */
3848
3849 static void
3850 analyze_modified_params (vec<access_p> representatives)
3851 {
3852   int i;
3853
3854   for (i = 0; i < func_param_count; i++)
3855     {
3856       struct access *repr;
3857
3858       for (repr = representatives[i];
3859            repr;
3860            repr = repr->next_grp)
3861         {
3862           struct access *access;
3863           bitmap visited;
3864           ao_ref ar;
3865
3866           if (no_accesses_p (repr))
3867             continue;
3868           if (!POINTER_TYPE_P (TREE_TYPE (repr->base))
3869               || repr->grp_maybe_modified)
3870             continue;
3871
3872           ao_ref_init (&ar, repr->expr);
3873           visited = BITMAP_ALLOC (NULL);
3874           for (access = repr; access; access = access->next_sibling)
3875             {
3876               /* All accesses are read ones, otherwise grp_maybe_modified would
3877                  be trivially set.  */
3878               walk_aliased_vdefs (&ar, gimple_vuse (access->stmt),
3879                                   mark_maybe_modified, repr, &visited);
3880               if (repr->grp_maybe_modified)
3881                 break;
3882             }
3883           BITMAP_FREE (visited);
3884         }
3885     }
3886 }
3887
3888 /* Propagate distances in bb_dereferences in the opposite direction than the
3889    control flow edges, in each step storing the maximum of the current value
3890    and the minimum of all successors.  These steps are repeated until the table
3891    stabilizes.  Note that BBs which might terminate the functions (according to
3892    final_bbs bitmap) never updated in this way.  */
3893
3894 static void
3895 propagate_dereference_distances (void)
3896 {
3897   basic_block bb;
3898
3899   auto_vec<basic_block> queue (last_basic_block_for_fn (cfun));
3900   queue.quick_push (ENTRY_BLOCK_PTR_FOR_FN (cfun));
3901   FOR_EACH_BB_FN (bb, cfun)
3902     {
3903       queue.quick_push (bb);
3904       bb->aux = bb;
3905     }
3906
3907   while (!queue.is_empty ())
3908     {
3909       edge_iterator ei;
3910       edge e;
3911       bool change = false;
3912       int i;
3913
3914       bb = queue.pop ();
3915       bb->aux = NULL;
3916
3917       if (bitmap_bit_p (final_bbs, bb->index))
3918         continue;
3919
3920       for (i = 0; i < func_param_count; i++)
3921         {
3922           int idx = bb->index * func_param_count + i;
3923           bool first = true;
3924           HOST_WIDE_INT inh = 0;
3925
3926           FOR_EACH_EDGE (e, ei, bb->succs)
3927           {
3928             int succ_idx = e->dest->index * func_param_count + i;
3929
3930             if (e->src == EXIT_BLOCK_PTR_FOR_FN (cfun))
3931               continue;
3932
3933             if (first)
3934               {
3935                 first = false;
3936                 inh = bb_dereferences [succ_idx];
3937               }
3938             else if (bb_dereferences [succ_idx] < inh)
3939               inh = bb_dereferences [succ_idx];
3940           }
3941
3942           if (!first && bb_dereferences[idx] < inh)
3943             {
3944               bb_dereferences[idx] = inh;
3945               change = true;
3946             }
3947         }
3948
3949       if (change && !bitmap_bit_p (final_bbs, bb->index))
3950         FOR_EACH_EDGE (e, ei, bb->preds)
3951           {
3952             if (e->src->aux)
3953               continue;
3954
3955             e->src->aux = e->src;
3956             queue.quick_push (e->src);
3957           }
3958     }
3959 }
3960
3961 /* Dump a dereferences TABLE with heading STR to file F.  */
3962
3963 static void
3964 dump_dereferences_table (FILE *f, const char *str, HOST_WIDE_INT *table)
3965 {
3966   basic_block bb;
3967
3968   fprintf (dump_file, "%s", str);
3969   FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
3970                   EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
3971     {
3972       fprintf (f, "%4i  %i   ", bb->index, bitmap_bit_p (final_bbs, bb->index));
3973       if (bb != EXIT_BLOCK_PTR_FOR_FN (cfun))
3974         {
3975           int i;
3976           for (i = 0; i < func_param_count; i++)
3977             {
3978               int idx = bb->index * func_param_count + i;
3979               fprintf (f, " %4" HOST_WIDE_INT_PRINT "d", table[idx]);
3980             }
3981         }
3982       fprintf (f, "\n");
3983     }
3984   fprintf (dump_file, "\n");
3985 }
3986
3987 /* Determine what (parts of) parameters passed by reference that are not
3988    assigned to are not certainly dereferenced in this function and thus the
3989    dereferencing cannot be safely moved to the caller without potentially
3990    introducing a segfault.  Mark such REPRESENTATIVES as
3991    grp_not_necessarilly_dereferenced.
3992
3993    The dereferenced maximum "distance," i.e. the offset + size of the accessed
3994    part is calculated rather than simple booleans are calculated for each
3995    pointer parameter to handle cases when only a fraction of the whole
3996    aggregate is allocated (see testsuite/gcc.c-torture/execute/ipa-sra-2.c for
3997    an example).
3998
3999    The maximum dereference distances for each pointer parameter and BB are
4000    already stored in bb_dereference.  This routine simply propagates these
4001    values upwards by propagate_dereference_distances and then compares the
4002    distances of individual parameters in the ENTRY BB to the equivalent
4003    distances of each representative of a (fraction of a) parameter.  */
4004
4005 static void
4006 analyze_caller_dereference_legality (vec<access_p> representatives)
4007 {
4008   int i;
4009
4010   if (dump_file && (dump_flags & TDF_DETAILS))
4011     dump_dereferences_table (dump_file,
4012                              "Dereference table before propagation:\n",
4013                              bb_dereferences);
4014
4015   propagate_dereference_distances ();
4016
4017   if (dump_file && (dump_flags & TDF_DETAILS))
4018     dump_dereferences_table (dump_file,
4019                              "Dereference table after propagation:\n",
4020                              bb_dereferences);
4021
4022   for (i = 0; i < func_param_count; i++)
4023     {
4024       struct access *repr = representatives[i];
4025       int idx = ENTRY_BLOCK_PTR_FOR_FN (cfun)->index * func_param_count + i;
4026
4027       if (!repr || no_accesses_p (repr))
4028         continue;
4029
4030       do
4031         {
4032           if ((repr->offset + repr->size) > bb_dereferences[idx])
4033             repr->grp_not_necessarilly_dereferenced = 1;
4034           repr = repr->next_grp;
4035         }
4036       while (repr);
4037     }
4038 }
4039
4040 /* Return the representative access for the parameter declaration PARM if it is
4041    a scalar passed by reference which is not written to and the pointer value
4042    is not used directly.  Thus, if it is legal to dereference it in the caller
4043    and we can rule out modifications through aliases, such parameter should be
4044    turned into one passed by value.  Return NULL otherwise.  */
4045
4046 static struct access *
4047 unmodified_by_ref_scalar_representative (tree parm)
4048 {
4049   int i, access_count;
4050   struct access *repr;
4051   vec<access_p> *access_vec;
4052
4053   access_vec = get_base_access_vector (parm);
4054   gcc_assert (access_vec);
4055   repr = (*access_vec)[0];
4056   if (repr->write)
4057     return NULL;
4058   repr->group_representative = repr;
4059
4060   access_count = access_vec->length ();
4061   for (i = 1; i < access_count; i++)
4062     {
4063       struct access *access = (*access_vec)[i];
4064       if (access->write)
4065         return NULL;
4066       access->group_representative = repr;
4067       access->next_sibling = repr->next_sibling;
4068       repr->next_sibling = access;
4069     }
4070
4071   repr->grp_read = 1;
4072   repr->grp_scalar_ptr = 1;
4073   return repr;
4074 }
4075
4076 /* Return true iff this ACCESS precludes IPA-SRA of the parameter it is
4077    associated with.  REQ_ALIGN is the minimum required alignment.  */
4078
4079 static bool
4080 access_precludes_ipa_sra_p (struct access *access, unsigned int req_align)
4081 {
4082   unsigned int exp_align;
4083   /* Avoid issues such as the second simple testcase in PR 42025.  The problem
4084      is incompatible assign in a call statement (and possibly even in asm
4085      statements).  This can be relaxed by using a new temporary but only for
4086      non-TREE_ADDRESSABLE types and is probably not worth the complexity. (In
4087      intraprocedural SRA we deal with this by keeping the old aggregate around,
4088      something we cannot do in IPA-SRA.)  */
4089   if (access->write
4090       && (is_gimple_call (access->stmt)
4091           || gimple_code (access->stmt) == GIMPLE_ASM))
4092     return true;
4093
4094   exp_align = get_object_alignment (access->expr);
4095   if (exp_align < req_align)
4096     return true;
4097
4098   return false;
4099 }
4100
4101
4102 /* Sort collected accesses for parameter PARM, identify representatives for
4103    each accessed region and link them together.  Return NULL if there are
4104    different but overlapping accesses, return the special ptr value meaning
4105    there are no accesses for this parameter if that is the case and return the
4106    first representative otherwise.  Set *RO_GRP if there is a group of accesses
4107    with only read (i.e. no write) accesses.  */
4108
4109 static struct access *
4110 splice_param_accesses (tree parm, bool *ro_grp)
4111 {
4112   int i, j, access_count, group_count;
4113   int agg_size, total_size = 0;
4114   struct access *access, *res, **prev_acc_ptr = &res;
4115   vec<access_p> *access_vec;
4116
4117   access_vec = get_base_access_vector (parm);
4118   if (!access_vec)
4119     return &no_accesses_representant;
4120   access_count = access_vec->length ();
4121
4122   access_vec->qsort (compare_access_positions);
4123
4124   i = 0;
4125   total_size = 0;
4126   group_count = 0;
4127   while (i < access_count)
4128     {
4129       bool modification;
4130       tree a1_alias_type;
4131       access = (*access_vec)[i];
4132       modification = access->write;
4133       if (access_precludes_ipa_sra_p (access, TYPE_ALIGN (access->type)))
4134         return NULL;
4135       a1_alias_type = reference_alias_ptr_type (access->expr);
4136
4137       /* Access is about to become group representative unless we find some
4138          nasty overlap which would preclude us from breaking this parameter
4139          apart. */
4140
4141       j = i + 1;
4142       while (j < access_count)
4143         {
4144           struct access *ac2 = (*access_vec)[j];
4145           if (ac2->offset != access->offset)
4146             {
4147               /* All or nothing law for parameters. */
4148               if (access->offset + access->size > ac2->offset)
4149                 return NULL;
4150               else
4151                 break;
4152             }
4153           else if (ac2->size != access->size)
4154             return NULL;
4155
4156           if (access_precludes_ipa_sra_p (ac2, TYPE_ALIGN (access->type))
4157               || (ac2->type != access->type
4158                   && (TREE_ADDRESSABLE (ac2->type)
4159                       || TREE_ADDRESSABLE (access->type)))
4160               || (reference_alias_ptr_type (ac2->expr) != a1_alias_type))
4161             return NULL;
4162
4163           modification |= ac2->write;
4164           ac2->group_representative = access;
4165           ac2->next_sibling = access->next_sibling;
4166           access->next_sibling = ac2;
4167           j++;
4168         }
4169
4170       group_count++;
4171       access->grp_maybe_modified = modification;
4172       if (!modification)
4173         *ro_grp = true;
4174       *prev_acc_ptr = access;
4175       prev_acc_ptr = &access->next_grp;
4176       total_size += access->size;
4177       i = j;
4178     }
4179
4180   if (POINTER_TYPE_P (TREE_TYPE (parm)))
4181     agg_size = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (TREE_TYPE (parm))));
4182   else
4183     agg_size = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (parm)));
4184   if (total_size >= agg_size)
4185     return NULL;
4186
4187   gcc_assert (group_count > 0);
4188   return res;
4189 }
4190
4191 /* Decide whether parameters with representative accesses given by REPR should
4192    be reduced into components.  */
4193
4194 static int
4195 decide_one_param_reduction (struct access *repr)
4196 {
4197   int total_size, cur_parm_size, agg_size, new_param_count, parm_size_limit;
4198   bool by_ref;
4199   tree parm;
4200
4201   parm = repr->base;
4202   cur_parm_size = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (parm)));
4203   gcc_assert (cur_parm_size > 0);
4204
4205   if (POINTER_TYPE_P (TREE_TYPE (parm)))
4206     {
4207       by_ref = true;
4208       agg_size = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (TREE_TYPE (parm))));
4209     }
4210   else
4211     {
4212       by_ref = false;
4213       agg_size = cur_parm_size;
4214     }
4215
4216   if (dump_file)
4217     {
4218       struct access *acc;
4219       fprintf (dump_file, "Evaluating PARAM group sizes for ");
4220       print_generic_expr (dump_file, parm, 0);
4221       fprintf (dump_file, " (UID: %u): \n", DECL_UID (parm));
4222       for (acc = repr; acc; acc = acc->next_grp)
4223         dump_access (dump_file, acc, true);
4224     }
4225
4226   total_size = 0;
4227   new_param_count = 0;
4228
4229   for (; repr; repr = repr->next_grp)
4230     {
4231       gcc_assert (parm == repr->base);
4232
4233       /* Taking the address of a non-addressable field is verboten.  */
4234       if (by_ref && repr->non_addressable)
4235         return 0;
4236
4237       /* Do not decompose a non-BLKmode param in a way that would
4238          create BLKmode params.  Especially for by-reference passing
4239          (thus, pointer-type param) this is hardly worthwhile.  */
4240       if (DECL_MODE (parm) != BLKmode
4241           && TYPE_MODE (repr->type) == BLKmode)
4242         return 0;
4243
4244       if (!by_ref || (!repr->grp_maybe_modified
4245                       && !repr->grp_not_necessarilly_dereferenced))
4246         total_size += repr->size;
4247       else
4248         total_size += cur_parm_size;
4249
4250       new_param_count++;
4251     }
4252
4253   gcc_assert (new_param_count > 0);
4254
4255   if (optimize_function_for_size_p (cfun))
4256     parm_size_limit = cur_parm_size;
4257   else
4258     parm_size_limit = (PARAM_VALUE (PARAM_IPA_SRA_PTR_GROWTH_FACTOR)
4259                        * cur_parm_size);
4260
4261   if (total_size < agg_size
4262       && total_size <= parm_size_limit)
4263     {
4264       if (dump_file)
4265         fprintf (dump_file, "    ....will be split into %i components\n",
4266                  new_param_count);
4267       return new_param_count;
4268     }
4269   else
4270     return 0;
4271 }
4272
4273 /* The order of the following enums is important, we need to do extra work for
4274    UNUSED_PARAMS, BY_VAL_ACCESSES and UNMODIF_BY_REF_ACCESSES.  */
4275 enum ipa_splicing_result { NO_GOOD_ACCESS, UNUSED_PARAMS, BY_VAL_ACCESSES,
4276                           MODIF_BY_REF_ACCESSES, UNMODIF_BY_REF_ACCESSES };
4277
4278 /* Identify representatives of all accesses to all candidate parameters for
4279    IPA-SRA.  Return result based on what representatives have been found. */
4280
4281 static enum ipa_splicing_result
4282 splice_all_param_accesses (vec<access_p> &representatives)
4283 {
4284   enum ipa_splicing_result result = NO_GOOD_ACCESS;
4285   tree parm;
4286   struct access *repr;
4287
4288   representatives.create (func_param_count);
4289
4290   for (parm = DECL_ARGUMENTS (current_function_decl);
4291        parm;
4292        parm = DECL_CHAIN (parm))
4293     {
4294       if (is_unused_scalar_param (parm))
4295         {
4296           representatives.quick_push (&no_accesses_representant);
4297           if (result == NO_GOOD_ACCESS)
4298             result = UNUSED_PARAMS;
4299         }
4300       else if (POINTER_TYPE_P (TREE_TYPE (parm))
4301                && is_gimple_reg_type (TREE_TYPE (TREE_TYPE (parm)))
4302                && bitmap_bit_p (candidate_bitmap, DECL_UID (parm)))
4303         {
4304           repr = unmodified_by_ref_scalar_representative (parm);
4305           representatives.quick_push (repr);
4306           if (repr)
4307             result = UNMODIF_BY_REF_ACCESSES;
4308         }
4309       else if (bitmap_bit_p (candidate_bitmap, DECL_UID (parm)))
4310         {
4311           bool ro_grp = false;
4312           repr = splice_param_accesses (parm, &ro_grp);
4313           representatives.quick_push (repr);
4314
4315           if (repr && !no_accesses_p (repr))
4316             {
4317               if (POINTER_TYPE_P (TREE_TYPE (parm)))
4318                 {
4319                   if (ro_grp)
4320                     result = UNMODIF_BY_REF_ACCESSES;
4321                   else if (result < MODIF_BY_REF_ACCESSES)
4322                     result = MODIF_BY_REF_ACCESSES;
4323                 }
4324               else if (result < BY_VAL_ACCESSES)
4325                 result = BY_VAL_ACCESSES;
4326             }
4327           else if (no_accesses_p (repr) && (result == NO_GOOD_ACCESS))
4328             result = UNUSED_PARAMS;
4329         }
4330       else
4331         representatives.quick_push (NULL);
4332     }
4333
4334   if (result == NO_GOOD_ACCESS)
4335     {
4336       representatives.release ();
4337       return NO_GOOD_ACCESS;
4338     }
4339
4340   return result;
4341 }
4342
4343 /* Return the index of BASE in PARMS.  Abort if it is not found.  */
4344
4345 static inline int
4346 get_param_index (tree base, vec<tree> parms)
4347 {
4348   int i, len;
4349
4350   len = parms.length ();
4351   for (i = 0; i < len; i++)
4352     if (parms[i] == base)
4353       return i;
4354   gcc_unreachable ();
4355 }
4356
4357 /* Convert the decisions made at the representative level into compact
4358    parameter adjustments.  REPRESENTATIVES are pointers to first
4359    representatives of each param accesses, ADJUSTMENTS_COUNT is the expected
4360    final number of adjustments.  */
4361
4362 static ipa_parm_adjustment_vec
4363 turn_representatives_into_adjustments (vec<access_p> representatives,
4364                                        int adjustments_count)
4365 {
4366   vec<tree> parms;
4367   ipa_parm_adjustment_vec adjustments;
4368   tree parm;
4369   int i;
4370
4371   gcc_assert (adjustments_count > 0);
4372   parms = ipa_get_vector_of_formal_parms (current_function_decl);
4373   adjustments.create (adjustments_count);
4374   parm = DECL_ARGUMENTS (current_function_decl);
4375   for (i = 0; i < func_param_count; i++, parm = DECL_CHAIN (parm))
4376     {
4377       struct access *repr = representatives[i];
4378
4379       if (!repr || no_accesses_p (repr))
4380         {
4381           struct ipa_parm_adjustment adj;
4382
4383           memset (&adj, 0, sizeof (adj));
4384           adj.base_index = get_param_index (parm, parms);
4385           adj.base = parm;
4386           if (!repr)
4387             adj.op = IPA_PARM_OP_COPY;
4388           else
4389             adj.op = IPA_PARM_OP_REMOVE;
4390           adj.arg_prefix = "ISRA";
4391           adjustments.quick_push (adj);
4392         }
4393       else
4394         {
4395           struct ipa_parm_adjustment adj;
4396           int index = get_param_index (parm, parms);
4397
4398           for (; repr; repr = repr->next_grp)
4399             {
4400               memset (&adj, 0, sizeof (adj));
4401               gcc_assert (repr->base == parm);
4402               adj.base_index = index;
4403               adj.base = repr->base;
4404               adj.type = repr->type;
4405               adj.alias_ptr_type = reference_alias_ptr_type (repr->expr);
4406               adj.offset = repr->offset;
4407               adj.by_ref = (POINTER_TYPE_P (TREE_TYPE (repr->base))
4408                             && (repr->grp_maybe_modified
4409                                 || repr->grp_not_necessarilly_dereferenced));
4410               adj.arg_prefix = "ISRA";
4411               adjustments.quick_push (adj);
4412             }
4413         }
4414     }
4415   parms.release ();
4416   return adjustments;
4417 }
4418
4419 /* Analyze the collected accesses and produce a plan what to do with the
4420    parameters in the form of adjustments, NULL meaning nothing.  */
4421
4422 static ipa_parm_adjustment_vec
4423 analyze_all_param_acesses (void)
4424 {
4425   enum ipa_splicing_result repr_state;
4426   bool proceed = false;
4427   int i, adjustments_count = 0;
4428   vec<access_p> representatives;
4429   ipa_parm_adjustment_vec adjustments;
4430
4431   repr_state = splice_all_param_accesses (representatives);
4432   if (repr_state == NO_GOOD_ACCESS)
4433     return ipa_parm_adjustment_vec ();
4434
4435   /* If there are any parameters passed by reference which are not modified
4436      directly, we need to check whether they can be modified indirectly.  */
4437   if (repr_state == UNMODIF_BY_REF_ACCESSES)
4438     {
4439       analyze_caller_dereference_legality (representatives);
4440       analyze_modified_params (representatives);
4441     }
4442
4443   for (i = 0; i < func_param_count; i++)
4444     {
4445       struct access *repr = representatives[i];
4446
4447       if (repr && !no_accesses_p (repr))
4448         {
4449           if (repr->grp_scalar_ptr)
4450             {
4451               adjustments_count++;
4452               if (repr->grp_not_necessarilly_dereferenced
4453                   || repr->grp_maybe_modified)
4454                 representatives[i] = NULL;
4455               else
4456                 {
4457                   proceed = true;
4458                   sra_stats.scalar_by_ref_to_by_val++;
4459                 }
4460             }
4461           else
4462             {
4463               int new_components = decide_one_param_reduction (repr);
4464
4465               if (new_components == 0)
4466                 {
4467                   representatives[i] = NULL;
4468                   adjustments_count++;
4469                 }
4470               else
4471                 {
4472                   adjustments_count += new_components;
4473                   sra_stats.aggregate_params_reduced++;
4474                   sra_stats.param_reductions_created += new_components;
4475                   proceed = true;
4476                 }
4477             }
4478         }
4479       else
4480         {
4481           if (no_accesses_p (repr))
4482             {
4483               proceed = true;
4484               sra_stats.deleted_unused_parameters++;
4485             }
4486           adjustments_count++;
4487         }
4488     }
4489
4490   if (!proceed && dump_file)
4491     fprintf (dump_file, "NOT proceeding to change params.\n");
4492
4493   if (proceed)
4494     adjustments = turn_representatives_into_adjustments (representatives,
4495                                                          adjustments_count);
4496   else
4497     adjustments = ipa_parm_adjustment_vec ();
4498
4499   representatives.release ();
4500   return adjustments;
4501 }
4502
4503 /* If a parameter replacement identified by ADJ does not yet exist in the form
4504    of declaration, create it and record it, otherwise return the previously
4505    created one.  */
4506
4507 static tree
4508 get_replaced_param_substitute (struct ipa_parm_adjustment *adj)
4509 {
4510   tree repl;
4511   if (!adj->new_ssa_base)
4512     {
4513       char *pretty_name = make_fancy_name (adj->base);
4514
4515       repl = create_tmp_reg (TREE_TYPE (adj->base), "ISR");
4516       DECL_NAME (repl) = get_identifier (pretty_name);
4517       obstack_free (&name_obstack, pretty_name);
4518
4519       adj->new_ssa_base = repl;
4520     }
4521   else
4522     repl = adj->new_ssa_base;
4523   return repl;
4524 }
4525
4526 /* Find the first adjustment for a particular parameter BASE in a vector of
4527    ADJUSTMENTS which is not a copy_param.  Return NULL if there is no such
4528    adjustment. */
4529
4530 static struct ipa_parm_adjustment *
4531 get_adjustment_for_base (ipa_parm_adjustment_vec adjustments, tree base)
4532 {
4533   int i, len;
4534
4535   len = adjustments.length ();
4536   for (i = 0; i < len; i++)
4537     {
4538       struct ipa_parm_adjustment *adj;
4539
4540       adj = &adjustments[i];
4541       if (adj->op != IPA_PARM_OP_COPY && adj->base == base)
4542         return adj;
4543     }
4544
4545   return NULL;
4546 }
4547
4548 /* If the statement STMT defines an SSA_NAME of a parameter which is to be
4549    removed because its value is not used, replace the SSA_NAME with a one
4550    relating to a created VAR_DECL together all of its uses and return true.
4551    ADJUSTMENTS is a pointer to an adjustments vector.  */
4552
4553 static bool
4554 replace_removed_params_ssa_names (gimple stmt,
4555                                   ipa_parm_adjustment_vec adjustments)
4556 {
4557   struct ipa_parm_adjustment *adj;
4558   tree lhs, decl, repl, name;
4559
4560   if (gimple_code (stmt) == GIMPLE_PHI)
4561     lhs = gimple_phi_result (stmt);
4562   else if (is_gimple_assign (stmt))
4563     lhs = gimple_assign_lhs (stmt);
4564   else if (is_gimple_call (stmt))
4565     lhs = gimple_call_lhs (stmt);
4566   else
4567     gcc_unreachable ();
4568
4569   if (TREE_CODE (lhs) != SSA_NAME)
4570     return false;
4571
4572   decl = SSA_NAME_VAR (lhs);
4573   if (decl == NULL_TREE
4574       || TREE_CODE (decl) != PARM_DECL)
4575     return false;
4576
4577   adj = get_adjustment_for_base (adjustments, decl);
4578   if (!adj)
4579     return false;
4580
4581   repl = get_replaced_param_substitute (adj);
4582   name = make_ssa_name (repl, stmt);
4583
4584   if (dump_file)
4585     {
4586       fprintf (dump_file, "replacing an SSA name of a removed param ");
4587       print_generic_expr (dump_file, lhs, 0);
4588       fprintf (dump_file, " with ");
4589       print_generic_expr (dump_file, name, 0);
4590       fprintf (dump_file, "\n");
4591     }
4592
4593   if (is_gimple_assign (stmt))
4594     gimple_assign_set_lhs (stmt, name);
4595   else if (is_gimple_call (stmt))
4596     gimple_call_set_lhs (stmt, name);
4597   else
4598     gimple_phi_set_result (as_a <gphi *> (stmt), name);
4599
4600   replace_uses_by (lhs, name);
4601   release_ssa_name (lhs);
4602   return true;
4603 }
4604
4605 /* If the statement STMT contains any expressions that need to replaced with a
4606    different one as noted by ADJUSTMENTS, do so.  Handle any potential type
4607    incompatibilities (GSI is used to accommodate conversion statements and must
4608    point to the statement).  Return true iff the statement was modified.  */
4609
4610 static bool
4611 sra_ipa_modify_assign (gimple stmt, gimple_stmt_iterator *gsi,
4612                        ipa_parm_adjustment_vec adjustments)
4613 {
4614   tree *lhs_p, *rhs_p;
4615   bool any;
4616
4617   if (!gimple_assign_single_p (stmt))
4618     return false;
4619
4620   rhs_p = gimple_assign_rhs1_ptr (stmt);
4621   lhs_p = gimple_assign_lhs_ptr (stmt);
4622
4623   any = ipa_modify_expr (rhs_p, false, adjustments);
4624   any |= ipa_modify_expr (lhs_p, false, adjustments);
4625   if (any)
4626     {
4627       tree new_rhs = NULL_TREE;
4628
4629       if (!useless_type_conversion_p (TREE_TYPE (*lhs_p), TREE_TYPE (*rhs_p)))
4630         {
4631           if (TREE_CODE (*rhs_p) == CONSTRUCTOR)
4632             {
4633               /* V_C_Es of constructors can cause trouble (PR 42714).  */
4634               if (is_gimple_reg_type (TREE_TYPE (*lhs_p)))
4635                 *rhs_p = build_zero_cst (TREE_TYPE (*lhs_p));
4636               else
4637                 *rhs_p = build_constructor (TREE_TYPE (*lhs_p),
4638                                             NULL);
4639             }
4640           else
4641             new_rhs = fold_build1_loc (gimple_location (stmt),
4642                                        VIEW_CONVERT_EXPR, TREE_TYPE (*lhs_p),
4643                                        *rhs_p);
4644         }
4645       else if (REFERENCE_CLASS_P (*rhs_p)
4646                && is_gimple_reg_type (TREE_TYPE (*lhs_p))
4647                && !is_gimple_reg (*lhs_p))
4648         /* This can happen when an assignment in between two single field
4649            structures is turned into an assignment in between two pointers to
4650            scalars (PR 42237).  */
4651         new_rhs = *rhs_p;
4652
4653       if (new_rhs)
4654         {
4655           tree tmp = force_gimple_operand_gsi (gsi, new_rhs, true, NULL_TREE,
4656                                                true, GSI_SAME_STMT);
4657
4658           gimple_assign_set_rhs_from_tree (gsi, tmp);
4659         }
4660
4661       return true;
4662     }
4663
4664   return false;
4665 }
4666
4667 /* Traverse the function body and all modifications as described in
4668    ADJUSTMENTS.  Return true iff the CFG has been changed.  */
4669
4670 bool
4671 ipa_sra_modify_function_body (ipa_parm_adjustment_vec adjustments)
4672 {
4673   bool cfg_changed = false;
4674   basic_block bb;
4675
4676   FOR_EACH_BB_FN (bb, cfun)
4677     {
4678       gimple_stmt_iterator gsi;
4679
4680       for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
4681         replace_removed_params_ssa_names (gsi_stmt (gsi), adjustments);
4682
4683       gsi = gsi_start_bb (bb);
4684       while (!gsi_end_p (gsi))
4685         {
4686           gimple stmt = gsi_stmt (gsi);
4687           bool modified = false;
4688           tree *t;
4689           unsigned i;
4690
4691           switch (gimple_code (stmt))
4692             {
4693             case GIMPLE_RETURN:
4694               t = gimple_return_retval_ptr (as_a <greturn *> (stmt));
4695               if (*t != NULL_TREE)
4696                 modified |= ipa_modify_expr (t, true, adjustments);
4697               break;
4698
4699             case GIMPLE_ASSIGN:
4700               modified |= sra_ipa_modify_assign (stmt, &gsi, adjustments);
4701               modified |= replace_removed_params_ssa_names (stmt, adjustments);
4702               break;
4703
4704             case GIMPLE_CALL:
4705               /* Operands must be processed before the lhs.  */
4706               for (i = 0; i < gimple_call_num_args (stmt); i++)
4707                 {
4708                   t = gimple_call_arg_ptr (stmt, i);
4709                   modified |= ipa_modify_expr (t, true, adjustments);
4710                 }
4711
4712               if (gimple_call_lhs (stmt))
4713                 {
4714                   t = gimple_call_lhs_ptr (stmt);
4715                   modified |= ipa_modify_expr (t, false, adjustments);
4716                   modified |= replace_removed_params_ssa_names (stmt,
4717                                                                 adjustments);
4718                 }
4719               break;
4720
4721             case GIMPLE_ASM:
4722               {
4723                 gasm *asm_stmt = as_a <gasm *> (stmt);
4724                 for (i = 0; i < gimple_asm_ninputs (asm_stmt); i++)
4725                   {
4726                     t = &TREE_VALUE (gimple_asm_input_op (asm_stmt, i));
4727                     modified |= ipa_modify_expr (t, true, adjustments);
4728                   }
4729                 for (i = 0; i < gimple_asm_noutputs (asm_stmt); i++)
4730                   {
4731                     t = &TREE_VALUE (gimple_asm_output_op (asm_stmt, i));
4732                     modified |= ipa_modify_expr (t, false, adjustments);
4733                   }
4734               }
4735               break;
4736
4737             default:
4738               break;
4739             }
4740
4741           if (modified)
4742             {
4743               update_stmt (stmt);
4744               if (maybe_clean_eh_stmt (stmt)
4745                   && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
4746                 cfg_changed = true;
4747             }
4748           gsi_next (&gsi);
4749         }
4750     }
4751
4752   return cfg_changed;
4753 }
4754
4755 /* Call gimple_debug_bind_reset_value on all debug statements describing
4756    gimple register parameters that are being removed or replaced.  */
4757
4758 static void
4759 sra_ipa_reset_debug_stmts (ipa_parm_adjustment_vec adjustments)
4760 {
4761   int i, len;
4762   gimple_stmt_iterator *gsip = NULL, gsi;
4763
4764   if (MAY_HAVE_DEBUG_STMTS && single_succ_p (ENTRY_BLOCK_PTR_FOR_FN (cfun)))
4765     {
4766       gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
4767       gsip = &gsi;
4768     }
4769   len = adjustments.length ();
4770   for (i = 0; i < len; i++)
4771     {
4772       struct ipa_parm_adjustment *adj;
4773       imm_use_iterator ui;
4774       gimple stmt;
4775       gdebug *def_temp;
4776       tree name, vexpr, copy = NULL_TREE;
4777       use_operand_p use_p;
4778
4779       adj = &adjustments[i];
4780       if (adj->op == IPA_PARM_OP_COPY || !is_gimple_reg (adj->base))
4781         continue;
4782       name = ssa_default_def (cfun, adj->base);
4783       vexpr = NULL;
4784       if (name)
4785         FOR_EACH_IMM_USE_STMT (stmt, ui, name)
4786           {
4787             if (gimple_clobber_p (stmt))
4788               {
4789                 gimple_stmt_iterator cgsi = gsi_for_stmt (stmt);
4790                 unlink_stmt_vdef (stmt);
4791                 gsi_remove (&cgsi, true);
4792                 release_defs (stmt);
4793                 continue;
4794               }
4795             /* All other users must have been removed by
4796                ipa_sra_modify_function_body.  */
4797             gcc_assert (is_gimple_debug (stmt));
4798             if (vexpr == NULL && gsip != NULL)
4799               {
4800                 gcc_assert (TREE_CODE (adj->base) == PARM_DECL);
4801                 vexpr = make_node (DEBUG_EXPR_DECL);
4802                 def_temp = gimple_build_debug_source_bind (vexpr, adj->base,
4803                                                            NULL);
4804                 DECL_ARTIFICIAL (vexpr) = 1;
4805                 TREE_TYPE (vexpr) = TREE_TYPE (name);
4806                 DECL_MODE (vexpr) = DECL_MODE (adj->base);
4807                 gsi_insert_before (gsip, def_temp, GSI_SAME_STMT);
4808               }
4809             if (vexpr)
4810               {
4811                 FOR_EACH_IMM_USE_ON_STMT (use_p, ui)
4812                   SET_USE (use_p, vexpr);
4813               }
4814             else
4815               gimple_debug_bind_reset_value (stmt);
4816             update_stmt (stmt);
4817           }
4818       /* Create a VAR_DECL for debug info purposes.  */
4819       if (!DECL_IGNORED_P (adj->base))
4820         {
4821           copy = build_decl (DECL_SOURCE_LOCATION (current_function_decl),
4822                              VAR_DECL, DECL_NAME (adj->base),
4823                              TREE_TYPE (adj->base));
4824           if (DECL_PT_UID_SET_P (adj->base))
4825             SET_DECL_PT_UID (copy, DECL_PT_UID (adj->base));
4826           TREE_ADDRESSABLE (copy) = TREE_ADDRESSABLE (adj->base);
4827           TREE_READONLY (copy) = TREE_READONLY (adj->base);
4828           TREE_THIS_VOLATILE (copy) = TREE_THIS_VOLATILE (adj->base);
4829           DECL_GIMPLE_REG_P (copy) = DECL_GIMPLE_REG_P (adj->base);
4830           DECL_ARTIFICIAL (copy) = DECL_ARTIFICIAL (adj->base);
4831           DECL_IGNORED_P (copy) = DECL_IGNORED_P (adj->base);
4832           DECL_ABSTRACT_ORIGIN (copy) = DECL_ORIGIN (adj->base);
4833           DECL_SEEN_IN_BIND_EXPR_P (copy) = 1;
4834           SET_DECL_RTL (copy, 0);
4835           TREE_USED (copy) = 1;
4836           DECL_CONTEXT (copy) = current_function_decl;
4837           add_local_decl (cfun, copy);
4838           DECL_CHAIN (copy) =
4839             BLOCK_VARS (DECL_INITIAL (current_function_decl));
4840           BLOCK_VARS (DECL_INITIAL (current_function_decl)) = copy;
4841         }
4842       if (gsip != NULL && copy && target_for_debug_bind (adj->base))
4843         {
4844           gcc_assert (TREE_CODE (adj->base) == PARM_DECL);
4845           if (vexpr)
4846             def_temp = gimple_build_debug_bind (copy, vexpr, NULL);
4847           else
4848             def_temp = gimple_build_debug_source_bind (copy, adj->base,
4849                                                        NULL);
4850           gsi_insert_before (gsip, def_temp, GSI_SAME_STMT);
4851         }
4852     }
4853 }
4854
4855 /* Return false if all callers have at least as many actual arguments as there
4856    are formal parameters in the current function and that their types
4857    match.  */
4858
4859 static bool
4860 some_callers_have_mismatched_arguments_p (struct cgraph_node *node,
4861                                           void *data ATTRIBUTE_UNUSED)
4862 {
4863   struct cgraph_edge *cs;
4864   for (cs = node->callers; cs; cs = cs->next_caller)
4865     if (!cs->call_stmt || !callsite_arguments_match_p (cs->call_stmt))
4866       return true;
4867
4868   return false;
4869 }
4870
4871 /* Return false if all callers have vuse attached to a call statement.  */
4872
4873 static bool
4874 some_callers_have_no_vuse_p (struct cgraph_node *node,
4875                              void *data ATTRIBUTE_UNUSED)
4876 {
4877   struct cgraph_edge *cs;
4878   for (cs = node->callers; cs; cs = cs->next_caller)
4879     if (!cs->call_stmt || !gimple_vuse (cs->call_stmt))
4880       return true;
4881
4882   return false;
4883 }
4884
4885 /* Convert all callers of NODE.  */
4886
4887 static bool
4888 convert_callers_for_node (struct cgraph_node *node,
4889                           void *data)
4890 {
4891   ipa_parm_adjustment_vec *adjustments = (ipa_parm_adjustment_vec *) data;
4892   bitmap recomputed_callers = BITMAP_ALLOC (NULL);
4893   struct cgraph_edge *cs;
4894
4895   for (cs = node->callers; cs; cs = cs->next_caller)
4896     {
4897       push_cfun (DECL_STRUCT_FUNCTION (cs->caller->decl));
4898
4899       if (dump_file)
4900         fprintf (dump_file, "Adjusting call %s/%i -> %s/%i\n",
4901                  xstrdup (cs->caller->name ()),
4902                  cs->caller->order,
4903                  xstrdup (cs->callee->name ()),
4904                  cs->callee->order);
4905
4906       ipa_modify_call_arguments (cs, cs->call_stmt, *adjustments);
4907
4908       pop_cfun ();
4909     }
4910
4911   for (cs = node->callers; cs; cs = cs->next_caller)
4912     if (bitmap_set_bit (recomputed_callers, cs->caller->uid)
4913         && gimple_in_ssa_p (DECL_STRUCT_FUNCTION (cs->caller->decl)))
4914       compute_inline_parameters (cs->caller, true);
4915   BITMAP_FREE (recomputed_callers);
4916
4917   return true;
4918 }
4919
4920 /* Convert all callers of NODE to pass parameters as given in ADJUSTMENTS.  */
4921
4922 static void
4923 convert_callers (struct cgraph_node *node, tree old_decl,
4924                  ipa_parm_adjustment_vec adjustments)
4925 {
4926   basic_block this_block;
4927
4928   node->call_for_symbol_and_aliases (convert_callers_for_node,
4929                                      &adjustments, false);
4930
4931   if (!encountered_recursive_call)
4932     return;
4933
4934   FOR_EACH_BB_FN (this_block, cfun)
4935     {
4936       gimple_stmt_iterator gsi;
4937
4938       for (gsi = gsi_start_bb (this_block); !gsi_end_p (gsi); gsi_next (&gsi))
4939         {
4940           gcall *stmt;
4941           tree call_fndecl;
4942           stmt = dyn_cast <gcall *> (gsi_stmt (gsi));
4943           if (!stmt)
4944             continue;
4945           call_fndecl = gimple_call_fndecl (stmt);
4946           if (call_fndecl == old_decl)
4947             {
4948               if (dump_file)
4949                 fprintf (dump_file, "Adjusting recursive call");
4950               gimple_call_set_fndecl (stmt, node->decl);
4951               ipa_modify_call_arguments (NULL, stmt, adjustments);
4952             }
4953         }
4954     }
4955
4956   return;
4957 }
4958
4959 /* Perform all the modification required in IPA-SRA for NODE to have parameters
4960    as given in ADJUSTMENTS.  Return true iff the CFG has been changed.  */
4961
4962 static bool
4963 modify_function (struct cgraph_node *node, ipa_parm_adjustment_vec adjustments)
4964 {
4965   struct cgraph_node *new_node;
4966   bool cfg_changed;
4967
4968   cgraph_edge::rebuild_edges ();
4969   free_dominance_info (CDI_DOMINATORS);
4970   pop_cfun ();
4971
4972   /* This must be done after rebuilding cgraph edges for node above.
4973      Otherwise any recursive calls to node that are recorded in
4974      redirect_callers will be corrupted.  */
4975   vec<cgraph_edge *> redirect_callers = node->collect_callers ();
4976   new_node = node->create_version_clone_with_body (redirect_callers, NULL,
4977                                                    NULL, false, NULL, NULL,
4978                                                    "isra");
4979   redirect_callers.release ();
4980
4981   push_cfun (DECL_STRUCT_FUNCTION (new_node->decl));
4982   ipa_modify_formal_parameters (current_function_decl, adjustments);
4983   cfg_changed = ipa_sra_modify_function_body (adjustments);
4984   sra_ipa_reset_debug_stmts (adjustments);
4985   convert_callers (new_node, node->decl, adjustments);
4986   new_node->make_local ();
4987   return cfg_changed;
4988 }
4989
4990 /* Means of communication between ipa_sra_check_caller and
4991    ipa_sra_preliminary_function_checks.  */
4992
4993 struct ipa_sra_check_caller_data
4994 {
4995   bool has_callers;
4996   bool bad_arg_alignment;
4997   bool has_thunk;
4998 };
4999
5000 /* If NODE has a caller, mark that fact in DATA which is pointer to
5001    ipa_sra_check_caller_data.  Also check all aggregate arguments in all known
5002    calls if they are unit aligned and if not, set the appropriate flag in DATA
5003    too. */
5004
5005 static bool
5006 ipa_sra_check_caller (struct cgraph_node *node, void *data)
5007 {
5008   if (!node->callers)
5009     return false;
5010
5011   struct ipa_sra_check_caller_data *iscc;
5012   iscc = (struct ipa_sra_check_caller_data *) data;
5013   iscc->has_callers = true;
5014
5015   for (cgraph_edge *cs = node->callers; cs; cs = cs->next_caller)
5016     {
5017       if (cs->caller->thunk.thunk_p)
5018         {
5019           iscc->has_thunk = true;
5020           return true;
5021         }
5022       gimple call_stmt = cs->call_stmt;
5023       unsigned count = gimple_call_num_args (call_stmt);
5024       for (unsigned i = 0; i < count; i++)
5025         {
5026           tree arg = gimple_call_arg (call_stmt, i);
5027           if (is_gimple_reg (arg))
5028               continue;
5029
5030           tree offset;
5031           HOST_WIDE_INT bitsize, bitpos;
5032           machine_mode mode;
5033           int unsignedp, volatilep = 0;
5034           get_inner_reference (arg, &bitsize, &bitpos, &offset, &mode,
5035                                &unsignedp, &volatilep, false);
5036           if (bitpos % BITS_PER_UNIT)
5037             {
5038               iscc->bad_arg_alignment = true;
5039               return true;
5040             }
5041         }
5042     }
5043
5044   return false;
5045 }
5046
5047 /* Return false the function is apparently unsuitable for IPA-SRA based on it's
5048    attributes, return true otherwise.  NODE is the cgraph node of the current
5049    function.  */
5050
5051 static bool
5052 ipa_sra_preliminary_function_checks (struct cgraph_node *node)
5053 {
5054   if (!node->can_be_local_p ())
5055     {
5056       if (dump_file)
5057         fprintf (dump_file, "Function not local to this compilation unit.\n");
5058       return false;
5059     }
5060
5061   if (!node->local.can_change_signature)
5062     {
5063       if (dump_file)
5064         fprintf (dump_file, "Function can not change signature.\n");
5065       return false;
5066     }
5067
5068   if (!tree_versionable_function_p (node->decl))
5069     {
5070       if (dump_file)
5071         fprintf (dump_file, "Function is not versionable.\n");
5072       return false;
5073     }
5074
5075   if (!opt_for_fn (node->decl, optimize)
5076       || !opt_for_fn (node->decl, flag_ipa_sra))
5077     {
5078       if (dump_file)
5079         fprintf (dump_file, "Function not optimized.\n");
5080       return false;
5081     }
5082
5083   if (DECL_VIRTUAL_P (current_function_decl))
5084     {
5085       if (dump_file)
5086         fprintf (dump_file, "Function is a virtual method.\n");
5087       return false;
5088     }
5089
5090   if ((DECL_ONE_ONLY (node->decl) || DECL_EXTERNAL (node->decl))
5091       && inline_summaries->get (node)->size >= MAX_INLINE_INSNS_AUTO)
5092     {
5093       if (dump_file)
5094         fprintf (dump_file, "Function too big to be made truly local.\n");
5095       return false;
5096     }
5097
5098   if (cfun->stdarg)
5099     {
5100       if (dump_file)
5101         fprintf (dump_file, "Function uses stdarg. \n");
5102       return false;
5103     }
5104
5105   if (TYPE_ATTRIBUTES (TREE_TYPE (node->decl)))
5106     return false;
5107
5108   if (DECL_DISREGARD_INLINE_LIMITS (node->decl))
5109     {
5110       if (dump_file)
5111         fprintf (dump_file, "Always inline function will be inlined "
5112                  "anyway. \n");
5113       return false;
5114     }
5115
5116   struct ipa_sra_check_caller_data iscc;
5117   memset (&iscc, 0, sizeof(iscc));
5118   node->call_for_symbol_and_aliases (ipa_sra_check_caller, &iscc, true);
5119   if (!iscc.has_callers)
5120     {
5121       if (dump_file)
5122         fprintf (dump_file,
5123                  "Function has no callers in this compilation unit.\n");
5124       return false;
5125     }
5126
5127   if (iscc.bad_arg_alignment)
5128     {
5129       if (dump_file)
5130         fprintf (dump_file,
5131                  "A function call has an argument with non-unit alignment.\n");
5132       return false;
5133     }
5134
5135   if (iscc.has_thunk)
5136     {
5137       if (dump_file)
5138         fprintf (dump_file,
5139                  "A has thunk.\n");
5140       return false;
5141     }
5142
5143   return true;
5144 }
5145
5146 /* Perform early interprocedural SRA.  */
5147
5148 static unsigned int
5149 ipa_early_sra (void)
5150 {
5151   struct cgraph_node *node = cgraph_node::get (current_function_decl);
5152   ipa_parm_adjustment_vec adjustments;
5153   int ret = 0;
5154
5155   if (!ipa_sra_preliminary_function_checks (node))
5156     return 0;
5157
5158   sra_initialize ();
5159   sra_mode = SRA_MODE_EARLY_IPA;
5160
5161   if (!find_param_candidates ())
5162     {
5163       if (dump_file)
5164         fprintf (dump_file, "Function has no IPA-SRA candidates.\n");
5165       goto simple_out;
5166     }
5167
5168   if (node->call_for_symbol_and_aliases
5169        (some_callers_have_mismatched_arguments_p, NULL, true))
5170     {
5171       if (dump_file)
5172         fprintf (dump_file, "There are callers with insufficient number of "
5173                  "arguments or arguments with type mismatches.\n");
5174       goto simple_out;
5175     }
5176
5177   if (node->call_for_symbol_and_aliases
5178        (some_callers_have_no_vuse_p, NULL, true))
5179     {
5180       if (dump_file)
5181         fprintf (dump_file, "There are callers with no VUSE attached "
5182                  "to a call stmt.\n");
5183       goto simple_out;
5184     }
5185
5186   bb_dereferences = XCNEWVEC (HOST_WIDE_INT,
5187                                  func_param_count
5188                                  * last_basic_block_for_fn (cfun));
5189   final_bbs = BITMAP_ALLOC (NULL);
5190
5191   scan_function ();
5192   if (encountered_apply_args)
5193     {
5194       if (dump_file)
5195         fprintf (dump_file, "Function calls  __builtin_apply_args().\n");
5196       goto out;
5197     }
5198
5199   if (encountered_unchangable_recursive_call)
5200     {
5201       if (dump_file)
5202         fprintf (dump_file, "Function calls itself with insufficient "
5203                  "number of arguments.\n");
5204       goto out;
5205     }
5206
5207   adjustments = analyze_all_param_acesses ();
5208   if (!adjustments.exists ())
5209     goto out;
5210   if (dump_file)
5211     ipa_dump_param_adjustments (dump_file, adjustments, current_function_decl);
5212
5213   if (modify_function (node, adjustments))
5214     ret = TODO_update_ssa | TODO_cleanup_cfg;
5215   else
5216     ret = TODO_update_ssa;
5217   adjustments.release ();
5218
5219   statistics_counter_event (cfun, "Unused parameters deleted",
5220                             sra_stats.deleted_unused_parameters);
5221   statistics_counter_event (cfun, "Scalar parameters converted to by-value",
5222                             sra_stats.scalar_by_ref_to_by_val);
5223   statistics_counter_event (cfun, "Aggregate parameters broken up",
5224                             sra_stats.aggregate_params_reduced);
5225   statistics_counter_event (cfun, "Aggregate parameter components created",
5226                             sra_stats.param_reductions_created);
5227
5228  out:
5229   BITMAP_FREE (final_bbs);
5230   free (bb_dereferences);
5231  simple_out:
5232   sra_deinitialize ();
5233   return ret;
5234 }
5235
5236 namespace {
5237
5238 const pass_data pass_data_early_ipa_sra =
5239 {
5240   GIMPLE_PASS, /* type */
5241   "eipa_sra", /* name */
5242   OPTGROUP_NONE, /* optinfo_flags */
5243   TV_IPA_SRA, /* tv_id */
5244   0, /* properties_required */
5245   0, /* properties_provided */
5246   0, /* properties_destroyed */
5247   0, /* todo_flags_start */
5248   TODO_dump_symtab, /* todo_flags_finish */
5249 };
5250
5251 class pass_early_ipa_sra : public gimple_opt_pass
5252 {
5253 public:
5254   pass_early_ipa_sra (gcc::context *ctxt)
5255     : gimple_opt_pass (pass_data_early_ipa_sra, ctxt)
5256   {}
5257
5258   /* opt_pass methods: */
5259   virtual bool gate (function *) { return flag_ipa_sra && dbg_cnt (eipa_sra); }
5260   virtual unsigned int execute (function *) { return ipa_early_sra (); }
5261
5262 }; // class pass_early_ipa_sra
5263
5264 } // anon namespace
5265
5266 gimple_opt_pass *
5267 make_pass_early_ipa_sra (gcc::context *ctxt)
5268 {
5269   return new pass_early_ipa_sra (ctxt);
5270 }