gcc/var-tracking.c

   1 /* Variable tracking routines for the GNU compiler.
   2    Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT
  12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  14    License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GCC; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19    02111-1307, USA.  */
  20
  21 /* This file contains the variable tracking pass.  It computes where
  22    variables are located (which registers or where in memory) at each position
  23    in instruction stream and emits notes describing the locations.
  24    Debug information (DWARF2 location lists) is finally generated from
  25    these notes.
  26    With this debug information, it is possible to show variables
  27    even when debugging optimized code.
  28
  29    How does the variable tracking pass work?
  30
  31    First, it scans RTL code for uses, stores and clobbers (register/memory
  32    references in instructions), for call insns and for stack adjustments
  33    separately for each basic block and saves them to an array of micro
  34    operations.
  35    The micro operations of one instruction are ordered so that
  36    pre-modifying stack adjustment < use < use with no var < call insn <
  37      < set < clobber < post-modifying stack adjustment
  38
  39    Then, a forward dataflow analysis is performed to find out how locations
  40    of variables change through code and to propagate the variable locations
  41    along control flow graph.
  42    The IN set for basic block BB is computed as a union of OUT sets of BB's
  43    predecessors, the OUT set for BB is copied from the IN set for BB and
  44    is changed according to micro operations in BB.
  45
  46    The IN and OUT sets for basic blocks consist of a current stack adjustment
  47    (used for adjusting offset of variables addressed using stack pointer),
  48    the table of structures describing the locations of parts of a variable
  49    and for each physical register a linked list for each physical register.
  50    The linked list is a list of variable parts stored in the register,
  51    i.e. it is a list of triplets (reg, decl, offset) where decl is
  52    REG_EXPR (reg) and offset is REG_OFFSET (reg).  The linked list is used for
  53    effective deleting appropriate variable parts when we set or clobber the
  54    register.
  55
  56    There may be more than one variable part in a register.  The linked lists
  57    should be pretty short so it is a good data structure here.
  58    For example in the following code, register allocator may assign same
  59    register to variables A and B, and both of them are stored in the same
  60    register in CODE:
  61
  62      if (cond)
  63        set A;
  64      else
  65        set B;
  66      CODE;
  67      if (cond)
  68        use A;
  69      else
  70        use B;
  71
  72    Finally, the NOTE_INSN_VAR_LOCATION notes describing the variable locations
  73    are emitted to appropriate positions in RTL code.  Each such a note describes
  74    the location of one variable at the point in instruction stream where the
  75    note is.  There is no need to emit a note for each variable before each
  76    instruction, we only emit these notes where the location of variable changes
  77    (this means that we also emit notes for changes between the OUT set of the
  78    previous block and the IN set of the current block).
  79
  80    The notes consist of two parts:
  81    1. the declaration (from REG_EXPR or MEM_EXPR)
  82    2. the location of a variable - it is either a simple register/memory
  83       reference (for simple variables, for example int),
  84       or a parallel of register/memory references (for a large variables
  85       which consist of several parts, for example long long).
  86
  87 */
  88
  89 #include "config.h"
  90 #include "system.h"
  91 #include "coretypes.h"
  92 #include "tm.h"
  93 #include "rtl.h"
  94 #include "tree.h"
  95 #include "hard-reg-set.h"
  96 #include "basic-block.h"
  97 #include "flags.h"
  98 #include "output.h"
  99 #include "insn-config.h"
 100 #include "reload.h"
 101 #include "sbitmap.h"
 102 #include "alloc-pool.h"
 103 #include "fibheap.h"
 104 #include "hashtab.h"
 105
 106 /* Type of micro operation.  */
 107 enum micro_operation_type
 108 {
 109   MO_USE,       /* Use location (REG or MEM).  */
 110   MO_USE_NO_VAR,/* Use location which is not associated with a variable
 111                    or the variable is not trackable.  */
 112   MO_SET,       /* Set location.  */
 113   MO_CLOBBER,   /* Clobber location.  */
 114   MO_CALL,      /* Call insn.  */
 115   MO_ADJUST     /* Adjust stack pointer.  */
 116 };
 117
 118 /* Where shall the note be emitted?  BEFORE or AFTER the instruction.  */
 119 enum emit_note_where
 120 {
 121   EMIT_NOTE_BEFORE_INSN,
 122   EMIT_NOTE_AFTER_INSN
 123 };
 124
 125 /* Structure holding information about micro operation.  */
 126 typedef struct micro_operation_def
 127 {
 128   /* Type of micro operation.  */
 129   enum micro_operation_type type;
 130
 131   union {
 132     /* Location.  */
 133     rtx loc;
 134
 135     /* Stack adjustment.  */
 136     HOST_WIDE_INT adjust;
 137   } u;
 138
 139   /* The instruction which the micro operation is in.  */
 140   rtx insn;
 141 } micro_operation;
 142
 143 /* Structure for passing some other parameters to function
 144    emit_note_insn_var_location.  */
 145 typedef struct emit_note_data_def
 146 {
 147   /* The instruction which the note will be emitted before/after.  */
 148   rtx insn;
 149
 150   /* Where the note will be emitted (before/after insn)?  */
 151   enum emit_note_where where;
 152 } emit_note_data;
 153
 154 /* Description of location of a part of a variable.  The content of a physical
 155    register is described by a chain of these structures.
 156    The chains are pretty short (usually 1 or 2 elements) and thus
 157    chain is the best data structure.  */
 158 typedef struct attrs_def
 159 {
 160   /* Pointer to next member of the list.  */
 161   struct attrs_def *next;
 162
 163   /* The rtx of register.  */
 164   rtx loc;
 165
 166   /* The declaration corresponding to LOC.  */
 167   tree decl;
 168
 169   /* Offset from start of DECL.  */
 170   HOST_WIDE_INT offset;
 171 } *attrs;
 172
 173 /* Structure holding the IN or OUT set for a basic block.  */
 174 typedef struct dataflow_set_def
 175 {
 176   /* Adjustment of stack offset.  */
 177   HOST_WIDE_INT stack_adjust;
 178
 179   /* Attributes for registers (lists of attrs).  */
 180   attrs regs[FIRST_PSEUDO_REGISTER];
 181
 182   /* Variable locations.  */
 183   htab_t vars;
 184 } dataflow_set;
 185
 186 /* The structure (one for each basic block) containing the information
 187    needed for variable tracking.  */
 188 typedef struct variable_tracking_info_def
 189 {
 190   /* Number of micro operations stored in the MOS array.  */
 191   int n_mos;
 192
 193   /* The array of micro operations.  */
 194   micro_operation *mos;
 195
 196   /* The IN and OUT set for dataflow analysis.  */
 197   dataflow_set in;
 198   dataflow_set out;
 199
 200   /* Has the block been visited in DFS?  */
 201   bool visited;
 202 } *variable_tracking_info;
 203
 204 /* Structure for chaining the locations.  */
 205 typedef struct location_chain_def
 206 {
 207   /* Next element in the chain.  */
 208   struct location_chain_def *next;
 209
 210   /* The location (REG or MEM).  */
 211   rtx loc;
 212 } *location_chain;
 213
 214 /* Structure describing one part of variable.  */
 215 typedef struct variable_part_def
 216 {
 217   /* Chain of locations of the part.  */
 218   location_chain loc_chain;
 219
 220   /* Location which was last emitted to location list.  */
 221   rtx cur_loc;
 222
 223   /* The offset in the variable.  */
 224   HOST_WIDE_INT offset;
 225 } variable_part;
 226
 227 /* Maximum number of location parts.  */
 228 #define MAX_VAR_PARTS 16
 229
 230 /* Structure describing where the variable is located.  */
 231 typedef struct variable_def
 232 {
 233   /* The declaration of the variable.  */
 234   tree decl;
 235
 236   /* Reference count.  */
 237   int refcount;
 238
 239   /* Number of variable parts.  */
 240   int n_var_parts;
 241
 242   /* The variable parts.  */
 243   variable_part var_part[MAX_VAR_PARTS];
 244 } *variable;
 245
 246 /* Hash function for DECL for VARIABLE_HTAB.  */
 247 #define VARIABLE_HASH_VAL(decl) ((size_t) (decl))
 248
 249 /* Pointer to the BB's information specific to variable tracking pass.  */
 250 #define VTI(BB) ((variable_tracking_info) (BB)->aux)
 251
 252 /* Alloc pool for struct attrs_def.  */
 253 static alloc_pool attrs_pool;
 254
 255 /* Alloc pool for struct variable_def.  */
 256 static alloc_pool var_pool;
 257
 258 /* Alloc pool for struct location_chain_def.  */
 259 static alloc_pool loc_chain_pool;
 260
 261 /* Changed variables, notes will be emitted for them.  */
 262 static htab_t changed_variables;
 263
 264 /* Shall notes be emitted?  */
 265 static bool emit_notes;
 266
 267 /* Fake variable for stack pointer.  */
 268 tree frame_base_decl;
 269
 270 /* Stack adjust caused by function prologue.  */
 271 static HOST_WIDE_INT frame_stack_adjust;
 272
 273 /* Local function prototypes.  */
 274 static void stack_adjust_offset_pre_post (rtx, HOST_WIDE_INT *,
 275                                           HOST_WIDE_INT *);
 276 static void insn_stack_adjust_offset_pre_post (rtx, HOST_WIDE_INT *,
 277                                                HOST_WIDE_INT *);
 278 static void bb_stack_adjust_offset (basic_block);
 279 static HOST_WIDE_INT prologue_stack_adjust (void);
 280 static bool vt_stack_adjustments (void);
 281 static rtx adjust_stack_reference (rtx, HOST_WIDE_INT);
 282 static hashval_t variable_htab_hash (const void *);
 283 static int variable_htab_eq (const void *, const void *);
 284 static void variable_htab_free (void *);
 285
 286 static void init_attrs_list_set (attrs *);
 287 static void attrs_list_clear (attrs *);
 288 static attrs attrs_list_member (attrs, tree, HOST_WIDE_INT);
 289 static void attrs_list_insert (attrs *, tree, HOST_WIDE_INT, rtx);
 290 static void attrs_list_copy (attrs *, attrs);
 291 static void attrs_list_union (attrs *, attrs);
 292
 293 static void vars_clear (htab_t);
 294 static variable unshare_variable (dataflow_set *set, variable var);
 295 static int vars_copy_1 (void **, void *);
 296 static void vars_copy (htab_t, htab_t);
 297 static void var_reg_delete_and_set (dataflow_set *, rtx);
 298 static void var_reg_delete (dataflow_set *, rtx);
 299 static void var_regno_delete (dataflow_set *, int);
 300 static void var_mem_delete_and_set (dataflow_set *, rtx);
 301 static void var_mem_delete (dataflow_set *, rtx);
 302
 303 static void dataflow_set_init (dataflow_set *, int);
 304 static void dataflow_set_clear (dataflow_set *);
 305 static void dataflow_set_copy (dataflow_set *, dataflow_set *);
 306 static int variable_union_info_cmp_pos (const void *, const void *);
 307 static int variable_union (void **, void *);
 308 static void dataflow_set_union (dataflow_set *, dataflow_set *);
 309 static bool variable_part_different_p (variable_part *, variable_part *);
 310 static bool variable_different_p (variable, variable, bool);
 311 static int dataflow_set_different_1 (void **, void *);
 312 static int dataflow_set_different_2 (void **, void *);
 313 static bool dataflow_set_different (dataflow_set *, dataflow_set *);
 314 static void dataflow_set_destroy (dataflow_set *);
 315
 316 static bool contains_symbol_ref (rtx);
 317 static bool track_expr_p (tree);
 318 static int count_uses (rtx *, void *);
 319 static void count_uses_1 (rtx *, void *);
 320 static void count_stores (rtx, rtx, void *);
 321 static int add_uses (rtx *, void *);
 322 static void add_uses_1 (rtx *, void *);
 323 static void add_stores (rtx, rtx, void *);
 324 static bool compute_bb_dataflow (basic_block);
 325 static void vt_find_locations (void);
 326
 327 static void dump_attrs_list (attrs);
 328 static int dump_variable (void **, void *);
 329 static void dump_vars (htab_t);
 330 static void dump_dataflow_set (dataflow_set *);
 331 static void dump_dataflow_sets (void);
 332
 333 static void variable_was_changed (variable, htab_t);
 334 static void set_frame_base_location (dataflow_set *, rtx);
 335 static void set_variable_part (dataflow_set *, rtx, tree, HOST_WIDE_INT);
 336 static void delete_variable_part (dataflow_set *, rtx, tree, HOST_WIDE_INT);
 337 static int emit_note_insn_var_location (void **, void *);
 338 static void emit_notes_for_changes (rtx, enum emit_note_where);
 339 static int emit_notes_for_differences_1 (void **, void *);
 340 static int emit_notes_for_differences_2 (void **, void *);
 341 static void emit_notes_for_differences (rtx, dataflow_set *, dataflow_set *);
 342 static void emit_notes_in_bb (basic_block);
 343 static void vt_emit_notes (void);
 344
 345 static bool vt_get_decl_and_offset (rtx, tree *, HOST_WIDE_INT *);
 346 static void vt_add_function_parameters (void);
 347 static void vt_initialize (void);
 348 static void vt_finalize (void);
 349
 350 /* Given a SET, calculate the amount of stack adjustment it contains
 351    PRE- and POST-modifying stack pointer.
 352    This function is similar to stack_adjust_offset.  */
 353
 354 static void
 355 stack_adjust_offset_pre_post (rtx pattern, HOST_WIDE_INT *pre,
 356                               HOST_WIDE_INT *post)
 357 {
 358   rtx src = SET_SRC (pattern);
 359   rtx dest = SET_DEST (pattern);
 360   enum rtx_code code;
 361
 362   if (dest == stack_pointer_rtx)
 363     {
 364       /* (set (reg sp) (plus (reg sp) (const_int))) */
 365       code = GET_CODE (src);
 366       if (! (code == PLUS || code == MINUS)
 367           || XEXP (src, 0) != stack_pointer_rtx
 368           || GET_CODE (XEXP (src, 1)) != CONST_INT)
 369         return;
 370
 371       if (code == MINUS)
 372         *post += INTVAL (XEXP (src, 1));
 373       else
 374         *post -= INTVAL (XEXP (src, 1));
 375     }
 376   else if (MEM_P (dest))
 377     {
 378       /* (set (mem (pre_dec (reg sp))) (foo)) */
 379       src = XEXP (dest, 0);
 380       code = GET_CODE (src);
 381
 382       switch (code)
 383         {
 384         case PRE_MODIFY:
 385         case POST_MODIFY:
 386           if (XEXP (src, 0) == stack_pointer_rtx)
 387             {
 388               rtx val = XEXP (XEXP (src, 1), 1);
 389               /* We handle only adjustments by constant amount.  */
 390               if (GET_CODE (XEXP (src, 1)) != PLUS ||
 391                   GET_CODE (val) != CONST_INT)
 392                 abort ();
 393               if (code == PRE_MODIFY)
 394                 *pre -= INTVAL (val);
 395               else
 396                 *post -= INTVAL (val);
 397               break;
 398             }
 399           return;
 400
 401         case PRE_DEC:
 402           if (XEXP (src, 0) == stack_pointer_rtx)
 403             {
 404               *pre += GET_MODE_SIZE (GET_MODE (dest));
 405               break;
 406             }
 407           return;
 408
 409         case POST_DEC:
 410           if (XEXP (src, 0) == stack_pointer_rtx)
 411             {
 412               *post += GET_MODE_SIZE (GET_MODE (dest));
 413               break;
 414             }
 415           return;
 416
 417         case PRE_INC:
 418           if (XEXP (src, 0) == stack_pointer_rtx)
 419             {
 420               *pre -= GET_MODE_SIZE (GET_MODE (dest));
 421               break;
 422             }
 423           return;
 424
 425         case POST_INC:
 426           if (XEXP (src, 0) == stack_pointer_rtx)
 427             {
 428               *post -= GET_MODE_SIZE (GET_MODE (dest));
 429               break;
 430             }
 431           return;
 432
 433         default:
 434           return;
 435         }
 436     }
 437 }
 438
 439 /* Given an INSN, calculate the amount of stack adjustment it contains
 440    PRE- and POST-modifying stack pointer.  */
 441
 442 static void
 443 insn_stack_adjust_offset_pre_post (rtx insn, HOST_WIDE_INT *pre,
 444                                    HOST_WIDE_INT *post)
 445 {
 446   *pre = 0;
 447   *post = 0;
 448
 449   if (GET_CODE (PATTERN (insn)) == SET)
 450     stack_adjust_offset_pre_post (PATTERN (insn), pre, post);
 451   else if (GET_CODE (PATTERN (insn)) == PARALLEL
 452            || GET_CODE (PATTERN (insn)) == SEQUENCE)
 453     {
 454       int i;
 455
 456       /* There may be stack adjustments inside compound insns.  Search
 457          for them.  */
 458       for ( i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
 459         if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET)
 460           stack_adjust_offset_pre_post (XVECEXP (PATTERN (insn), 0, i),
 461                                         pre, post);
 462     }
 463 }
 464
 465 /* Compute stack adjustment in basic block BB.  */
 466
 467 static void
 468 bb_stack_adjust_offset (basic_block bb)
 469 {
 470   HOST_WIDE_INT offset;
 471   int i;
 472
 473   offset = VTI (bb)->in.stack_adjust;
 474   for (i = 0; i < VTI (bb)->n_mos; i++)
 475     {
 476       if (VTI (bb)->mos[i].type == MO_ADJUST)
 477         offset += VTI (bb)->mos[i].u.adjust;
 478       else if (VTI (bb)->mos[i].type != MO_CALL)
 479         {
 480           if (MEM_P (VTI (bb)->mos[i].u.loc))
 481             {
 482               VTI (bb)->mos[i].u.loc
 483                 = adjust_stack_reference (VTI (bb)->mos[i].u.loc, -offset);
 484             }
 485         }
 486     }
 487   VTI (bb)->out.stack_adjust = offset;
 488 }
 489
 490 /* Compute stack adjustment caused by function prologue.  */
 491
 492 static HOST_WIDE_INT
 493 prologue_stack_adjust (void)
 494 {
 495   HOST_WIDE_INT offset = 0;
 496   basic_block bb = ENTRY_BLOCK_PTR->next_bb;
 497   rtx insn;
 498   rtx end;
 499
 500   if (!BB_END (bb))
 501     return 0;
 502
 503   end = NEXT_INSN (BB_END (bb));
 504   for (insn = BB_HEAD (bb); insn != end; insn = NEXT_INSN (insn))
 505     {
 506       if (NOTE_P (insn)
 507           && NOTE_LINE_NUMBER (insn) == NOTE_INSN_PROLOGUE_END)
 508         break;
 509
 510       if (INSN_P (insn))
 511         {
 512           HOST_WIDE_INT tmp;
 513
 514           insn_stack_adjust_offset_pre_post (insn, &tmp, &tmp);
 515           offset += tmp;
 516         }
 517     }
 518
 519   return offset;
 520 }
 521
 522 /* Compute stack adjustments for all blocks by traversing DFS tree.
 523    Return true when the adjustments on all incoming edges are consistent.
 524    Heavily borrowed from flow_depth_first_order_compute.  */
 525
 526 static bool
 527 vt_stack_adjustments (void)
 528 {
 529   edge_iterator *stack;
 530   int sp;
 531
 532   /* Initialize entry block.  */
 533   VTI (ENTRY_BLOCK_PTR)->visited = true;
 534   VTI (ENTRY_BLOCK_PTR)->out.stack_adjust = frame_stack_adjust;
 535
 536   /* Allocate stack for back-tracking up CFG.  */
 537   stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
 538   sp = 0;
 539
 540   /* Push the first edge on to the stack.  */
 541   stack[sp++] = ei_start (ENTRY_BLOCK_PTR->succs);
 542
 543   while (sp)
 544     {
 545       edge_iterator ei;
 546       basic_block src;
 547       basic_block dest;
 548
 549       /* Look at the edge on the top of the stack.  */
 550       ei = stack[sp - 1];
 551       src = ei_edge (ei)->src;
 552       dest = ei_edge (ei)->dest;
 553
 554       /* Check if the edge destination has been visited yet.  */
 555       if (!VTI (dest)->visited)
 556         {
 557           VTI (dest)->visited = true;
 558           VTI (dest)->in.stack_adjust = VTI (src)->out.stack_adjust;
 559           bb_stack_adjust_offset (dest);
 560
 561           if (EDGE_COUNT (dest->succs) > 0)
 562             /* Since the DEST node has been visited for the first
 563                time, check its successors.  */
 564             stack[sp++] = ei_start (dest->succs);
 565         }
 566       else
 567         {
 568           /* Check whether the adjustments on the edges are the same.  */
 569           if (VTI (dest)->in.stack_adjust != VTI (src)->out.stack_adjust)
 570             {
 571               free (stack);
 572               return false;
 573             }
 574
 575           if (! ei_one_before_end_p (ei))
 576             /* Go to the next edge.  */
 577             ei_next (&stack[sp - 1]);
 578           else
 579             /* Return to previous level if there are no more edges.  */
 580             sp--;
 581         }
 582     }
 583
 584   free (stack);
 585   return true;
 586 }
 587
 588 /* Adjust stack reference MEM by ADJUSTMENT bytes and return the new rtx.  */
 589
 590 static rtx
 591 adjust_stack_reference (rtx mem, HOST_WIDE_INT adjustment)
 592 {
 593   rtx adjusted_mem;
 594   rtx tmp;
 595
 596   if (adjustment == 0)
 597     return mem;
 598
 599   adjusted_mem = copy_rtx (mem);
 600   XEXP (adjusted_mem, 0) = replace_rtx (XEXP (adjusted_mem, 0),
 601                                         stack_pointer_rtx,
 602                                         gen_rtx_PLUS (Pmode, stack_pointer_rtx,
 603                                                       GEN_INT (adjustment)));
 604   tmp = simplify_rtx (XEXP (adjusted_mem, 0));
 605   if (tmp)
 606     XEXP (adjusted_mem, 0) = tmp;
 607
 608   return adjusted_mem;
 609 }
 610
 611 /* The hash function for variable_htab, computes the hash value
 612    from the declaration of variable X.  */
 613
 614 static hashval_t
 615 variable_htab_hash (const void *x)
 616 {
 617   const variable v = (const variable) x;
 618
 619   return (VARIABLE_HASH_VAL (v->decl));
 620 }
 621
 622 /* Compare the declaration of variable X with declaration Y.  */
 623
 624 static int
 625 variable_htab_eq (const void *x, const void *y)
 626 {
 627   const variable v = (const variable) x;
 628   const tree decl = (const tree) y;
 629
 630   return (VARIABLE_HASH_VAL (v->decl) == VARIABLE_HASH_VAL (decl));
 631 }
 632
 633 /* Free the element of VARIABLE_HTAB (its type is struct variable_def).  */
 634
 635 static void
 636 variable_htab_free (void *elem)
 637 {
 638   int i;
 639   variable var = (variable) elem;
 640   location_chain node, next;
 641
 642 #ifdef ENABLE_CHECKING
 643   if (var->refcount <= 0)
 644     abort ();
 645 #endif
 646
 647   var->refcount--;
 648   if (var->refcount > 0)
 649     return;
 650
 651   for (i = 0; i < var->n_var_parts; i++)
 652     {
 653       for (node = var->var_part[i].loc_chain; node; node = next)
 654         {
 655           next = node->next;
 656           pool_free (loc_chain_pool, node);
 657         }
 658       var->var_part[i].loc_chain = NULL;
 659     }
 660   pool_free (var_pool, var);
 661 }
 662
 663 /* Initialize the set (array) SET of attrs to empty lists.  */
 664
 665 static void
 666 init_attrs_list_set (attrs *set)
 667 {
 668   int i;
 669
 670   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 671     set[i] = NULL;
 672 }
 673
 674 /* Make the list *LISTP empty.  */
 675
 676 static void
 677 attrs_list_clear (attrs *listp)
 678 {
 679   attrs list, next;
 680
 681   for (list = *listp; list; list = next)
 682     {
 683       next = list->next;
 684       pool_free (attrs_pool, list);
 685     }
 686   *listp = NULL;
 687 }
 688
 689 /* Return true if the pair of DECL and OFFSET is the member of the LIST.  */
 690
 691 static attrs
 692 attrs_list_member (attrs list, tree decl, HOST_WIDE_INT offset)
 693 {
 694   for (; list; list = list->next)
 695     if (list->decl == decl && list->offset == offset)
 696       return list;
 697   return NULL;
 698 }
 699
 700 /* Insert the triplet DECL, OFFSET, LOC to the list *LISTP.  */
 701
 702 static void
 703 attrs_list_insert (attrs *listp, tree decl, HOST_WIDE_INT offset, rtx loc)
 704 {
 705   attrs list;
 706
 707   list = pool_alloc (attrs_pool);
 708   list->loc = loc;
 709   list->decl = decl;
 710   list->offset = offset;
 711   list->next = *listp;
 712   *listp = list;
 713 }
 714
 715 /* Copy all nodes from SRC and create a list *DSTP of the copies.  */
 716
 717 static void
 718 attrs_list_copy (attrs *dstp, attrs src)
 719 {
 720   attrs n;
 721
 722   attrs_list_clear (dstp);
 723   for (; src; src = src->next)
 724     {
 725       n = pool_alloc (attrs_pool);
 726       n->loc = src->loc;
 727       n->decl = src->decl;
 728       n->offset = src->offset;
 729       n->next = *dstp;
 730       *dstp = n;
 731     }
 732 }
 733
 734 /* Add all nodes from SRC which are not in *DSTP to *DSTP.  */
 735
 736 static void
 737 attrs_list_union (attrs *dstp, attrs src)
 738 {
 739   for (; src; src = src->next)
 740     {
 741       if (!attrs_list_member (*dstp, src->decl, src->offset))
 742         attrs_list_insert (dstp, src->decl, src->offset, src->loc);
 743     }
 744 }
 745
 746 /* Delete all variables from hash table VARS.  */
 747
 748 static void
 749 vars_clear (htab_t vars)
 750 {
 751   htab_empty (vars);
 752 }
 753
 754 /* Return a copy of a variable VAR and insert it to dataflow set SET.  */
 755
 756 static variable
 757 unshare_variable (dataflow_set *set, variable var)
 758 {
 759   void **slot;
 760   variable new_var;
 761   int i;
 762
 763   new_var = pool_alloc (var_pool);
 764   new_var->decl = var->decl;
 765   new_var->refcount = 1;
 766   var->refcount--;
 767   new_var->n_var_parts = var->n_var_parts;
 768
 769   for (i = 0; i < var->n_var_parts; i++)
 770     {
 771       location_chain node;
 772       location_chain *nextp;
 773
 774       new_var->var_part[i].offset = var->var_part[i].offset;
 775       nextp = &new_var->var_part[i].loc_chain;
 776       for (node = var->var_part[i].loc_chain; node; node = node->next)
 777         {
 778           location_chain new_lc;
 779
 780           new_lc = pool_alloc (loc_chain_pool);
 781           new_lc->next = NULL;
 782           new_lc->loc = node->loc;
 783
 784           *nextp = new_lc;
 785           nextp = &new_lc->next;
 786         }
 787
 788       /* We are at the basic block boundary when copying variable description
 789          so set the CUR_LOC to be the first element of the chain.  */
 790       if (new_var->var_part[i].loc_chain)
 791         new_var->var_part[i].cur_loc = new_var->var_part[i].loc_chain->loc;
 792       else
 793         new_var->var_part[i].cur_loc = NULL;
 794     }
 795
 796   slot = htab_find_slot_with_hash (set->vars, new_var->decl,
 797                                    VARIABLE_HASH_VAL (new_var->decl),
 798                                    INSERT);
 799   *slot = new_var;
 800   return new_var;
 801 }
 802
 803 /* Add a variable from *SLOT to hash table DATA and increase its reference
 804    count.  */
 805
 806 static int
 807 vars_copy_1 (void **slot, void *data)
 808 {
 809   htab_t dst = (htab_t) data;
 810   variable src, *dstp;
 811
 812   src = *(variable *) slot;
 813   src->refcount++;
 814
 815   dstp = (variable *) htab_find_slot_with_hash (dst, src->decl,
 816                                                 VARIABLE_HASH_VAL (src->decl),
 817                                                 INSERT);
 818   *dstp = src;
 819
 820   /* Continue traversing the hash table.  */
 821   return 1;
 822 }
 823
 824 /* Copy all variables from hash table SRC to hash table DST.  */
 825
 826 static void
 827 vars_copy (htab_t dst, htab_t src)
 828 {
 829   vars_clear (dst);
 830   htab_traverse (src, vars_copy_1, dst);
 831 }
 832
 833 /* Delete current content of register LOC in dataflow set SET
 834    and set the register to contain REG_EXPR (LOC), REG_OFFSET (LOC).  */
 835
 836 static void
 837 var_reg_delete_and_set (dataflow_set *set, rtx loc)
 838 {
 839   tree decl = REG_EXPR (loc);
 840   HOST_WIDE_INT offset = REG_OFFSET (loc);
 841   attrs node, next;
 842   attrs *nextp;
 843
 844   nextp = &set->regs[REGNO (loc)];
 845   for (node = *nextp; node; node = next)
 846     {
 847       next = node->next;
 848       if (node->decl != decl || node->offset != offset)
 849         {
 850           delete_variable_part (set, node->loc, node->decl, node->offset);
 851           pool_free (attrs_pool, node);
 852           *nextp = next;
 853         }
 854       else
 855         {
 856           node->loc = loc;
 857           nextp = &node->next;
 858         }
 859     }
 860   if (set->regs[REGNO (loc)] == NULL)
 861     attrs_list_insert (&set->regs[REGNO (loc)], decl, offset, loc);
 862   set_variable_part (set, loc, decl, offset);
 863 }
 864
 865 /* Delete current content of register LOC in dataflow set SET.  */
 866
 867 static void
 868 var_reg_delete (dataflow_set *set, rtx loc)
 869 {
 870   attrs *reg = &set->regs[REGNO (loc)];
 871   attrs node, next;
 872
 873   for (node = *reg; node; node = next)
 874     {
 875       next = node->next;
 876       delete_variable_part (set, node->loc, node->decl, node->offset);
 877       pool_free (attrs_pool, node);
 878     }
 879   *reg = NULL;
 880 }
 881
 882 /* Delete content of register with number REGNO in dataflow set SET.  */
 883
 884 static void
 885 var_regno_delete (dataflow_set *set, int regno)
 886 {
 887   attrs *reg = &set->regs[regno];
 888   attrs node, next;
 889
 890   for (node = *reg; node; node = next)
 891     {
 892       next = node->next;
 893       delete_variable_part (set, node->loc, node->decl, node->offset);
 894       pool_free (attrs_pool, node);
 895     }
 896   *reg = NULL;
 897 }
 898
 899 /* Delete and set the location part of variable MEM_EXPR (LOC)
 900    in dataflow set SET to LOC.
 901    Adjust the address first if it is stack pointer based.  */
 902
 903 static void
 904 var_mem_delete_and_set (dataflow_set *set, rtx loc)
 905 {
 906   tree decl = MEM_EXPR (loc);
 907   HOST_WIDE_INT offset = MEM_OFFSET (loc) ? INTVAL (MEM_OFFSET (loc)) : 0;
 908
 909   set_variable_part (set, loc, decl, offset);
 910 }
 911
 912 /* Delete the location part LOC from dataflow set SET.
 913    Adjust the address first if it is stack pointer based.  */
 914
 915 static void
 916 var_mem_delete (dataflow_set *set, rtx loc)
 917 {
 918   tree decl = MEM_EXPR (loc);
 919   HOST_WIDE_INT offset = MEM_OFFSET (loc) ? INTVAL (MEM_OFFSET (loc)) : 0;
 920
 921   delete_variable_part (set, loc, decl, offset);
 922 }
 923
 924 /* Initialize dataflow set SET to be empty.
 925    VARS_SIZE is the initial size of hash table VARS.  */
 926
 927 static void
 928 dataflow_set_init (dataflow_set *set, int vars_size)
 929 {
 930   init_attrs_list_set (set->regs);
 931   set->vars = htab_create (vars_size, variable_htab_hash, variable_htab_eq,
 932                            variable_htab_free);
 933   set->stack_adjust = 0;
 934 }
 935
 936 /* Delete the contents of dataflow set SET.  */
 937
 938 static void
 939 dataflow_set_clear (dataflow_set *set)
 940 {
 941   int i;
 942
 943   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 944     attrs_list_clear (&set->regs[i]);
 945
 946   vars_clear (set->vars);
 947 }
 948
 949 /* Copy the contents of dataflow set SRC to DST.  */
 950
 951 static void
 952 dataflow_set_copy (dataflow_set *dst, dataflow_set *src)
 953 {
 954   int i;
 955
 956   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 957     attrs_list_copy (&dst->regs[i], src->regs[i]);
 958
 959   vars_copy (dst->vars, src->vars);
 960   dst->stack_adjust = src->stack_adjust;
 961 }
 962
 963 /* Information for merging lists of locations for a given offset of variable.
 964  */
 965 struct variable_union_info
 966 {
 967   /* Node of the location chain.  */
 968   location_chain lc;
 969
 970   /* The sum of positions in the input chains.  */
 971   int pos;
 972
 973   /* The position in the chains of SRC and DST dataflow sets.  */
 974   int pos_src;
 975   int pos_dst;
 976 };
 977
 978 /* Compare function for qsort, order the structures by POS element.  */
 979
 980 static int
 981 variable_union_info_cmp_pos (const void *n1, const void *n2)
 982 {
 983   const struct variable_union_info *i1 = n1;
 984   const struct variable_union_info *i2 = n2;
 985
 986   if (i1->pos != i2->pos)
 987     return i1->pos - i2->pos;
 988
 989   return (i1->pos_dst - i2->pos_dst);
 990 }
 991
 992 /* Compute union of location parts of variable *SLOT and the same variable
 993    from hash table DATA.  Compute "sorted" union of the location chains
 994    for common offsets, i.e. the locations of a variable part are sorted by
 995    a priority where the priority is the sum of the positions in the 2 chains
 996    (if a location is only in one list the position in the second list is
 997    defined to be larger than the length of the chains).
 998    When we are updating the location parts the newest location is in the
 999    beginning of the chain, so when we do the described "sorted" union
1000    we keep the newest locations in the beginning.  */
1001
1002 static int
1003 variable_union (void **slot, void *data)
1004 {
1005   variable src, dst, *dstp;
1006   dataflow_set *set = (dataflow_set *) data;
1007   int i, j, k;
1008
1009   src = *(variable *) slot;
1010   dstp = (variable *) htab_find_slot_with_hash (set->vars, src->decl,
1011                                                 VARIABLE_HASH_VAL (src->decl),
1012                                                 INSERT);
1013   if (!*dstp)
1014     {
1015       src->refcount++;
1016
1017       /* If CUR_LOC of some variable part is not the first element of
1018          the location chain we are going to change it so we have to make
1019          a copy of the variable.  */
1020       for (k = 0; k < src->n_var_parts; k++)
1021         {
1022           if (src->var_part[k].loc_chain)
1023             {
1024 #ifdef ENABLE_CHECKING
1025               if (src->var_part[k].cur_loc == NULL)
1026                 abort ();
1027 #endif
1028               if (src->var_part[k].cur_loc != src->var_part[k].loc_chain->loc)
1029                 break;
1030             }
1031 #ifdef ENABLE_CHECKING
1032           else
1033             {
1034               if (src->var_part[k].cur_loc != NULL)
1035                 abort ();
1036             }
1037 #endif
1038         }
1039       if (k < src->n_var_parts)
1040         unshare_variable (set, src);
1041       else
1042         *dstp = src;
1043
1044       /* Continue traversing the hash table.  */
1045       return 1;
1046     }
1047   else
1048     dst = *dstp;
1049
1050 #ifdef ENABLE_CHECKING
1051   if (src->n_var_parts == 0)
1052     abort ();
1053 #endif
1054
1055   /* Count the number of location parts, result is K.  */
1056   for (i = 0, j = 0, k = 0;
1057        i < src->n_var_parts && j < dst->n_var_parts; k++)
1058     {
1059       if (src->var_part[i].offset == dst->var_part[j].offset)
1060         {
1061           i++;
1062           j++;
1063         }
1064       else if (src->var_part[i].offset < dst->var_part[j].offset)
1065         i++;
1066       else
1067         j++;
1068     }
1069   k += src->n_var_parts - i;
1070   k += dst->n_var_parts - j;
1071 #ifdef ENABLE_CHECKING
1072   /* We track only variables whose size is <= MAX_VAR_PARTS bytes
1073      thus there are at most MAX_VAR_PARTS different offsets.  */
1074   if (k > MAX_VAR_PARTS)
1075     abort ();
1076 #endif
1077
1078   if (dst->refcount > 1 && dst->n_var_parts != k)
1079     dst = unshare_variable (set, dst);
1080
1081   i = src->n_var_parts - 1;
1082   j = dst->n_var_parts - 1;
1083   dst->n_var_parts = k;
1084
1085   for (k--; k >= 0; k--)
1086     {
1087       location_chain node, node2;
1088
1089       if (i >= 0 && j >= 0
1090           && src->var_part[i].offset == dst->var_part[j].offset)
1091         {
1092           /* Compute the "sorted" union of the chains, i.e. the locations which
1093              are in both chains go first, they are sorted by the sum of
1094              positions in the chains.  */
1095           int dst_l, src_l;
1096           int ii, jj, n;
1097           struct variable_union_info *vui;
1098
1099           /* If DST is shared compare the location chains.
1100              If they are different we will modify the chain in DST with
1101              high probability so make a copy of DST.  */
1102           if (dst->refcount > 1)
1103             {
1104               for (node = src->var_part[i].loc_chain,
1105                    node2 = dst->var_part[j].loc_chain; node && node2;
1106                    node = node->next, node2 = node2->next)
1107                 {
1108                   if (!((REG_P (node2->loc)
1109                          && REG_P (node->loc)
1110                          && REGNO (node2->loc) == REGNO (node->loc))
1111                         || rtx_equal_p (node2->loc, node->loc)))
1112                     break;
1113                 }
1114               if (node || node2)
1115                 dst = unshare_variable (set, dst);
1116             }
1117
1118           src_l = 0;
1119           for (node = src->var_part[i].loc_chain; node; node = node->next)
1120             src_l++;
1121           dst_l = 0;
1122           for (node = dst->var_part[j].loc_chain; node; node = node->next)
1123             dst_l++;
1124           vui = xcalloc (src_l + dst_l, sizeof (struct variable_union_info));
1125
1126           /* Fill in the locations from DST.  */
1127           for (node = dst->var_part[j].loc_chain, jj = 0; node;
1128                node = node->next, jj++)
1129             {
1130               vui[jj].lc = node;
1131               vui[jj].pos_dst = jj;
1132
1133               /* Value larger than a sum of 2 valid positions.  */
1134               vui[jj].pos_src = src_l + dst_l;
1135             }
1136
1137           /* Fill in the locations from SRC.  */
1138           n = dst_l;
1139           for (node = src->var_part[i].loc_chain, ii = 0; node;
1140                node = node->next, ii++)
1141             {
1142               /* Find location from NODE.  */
1143               for (jj = 0; jj < dst_l; jj++)
1144                 {
1145                   if ((REG_P (vui[jj].lc->loc)
1146                        && REG_P (node->loc)
1147                        && REGNO (vui[jj].lc->loc) == REGNO (node->loc))
1148                       || rtx_equal_p (vui[jj].lc->loc, node->loc))
1149                     {
1150                       vui[jj].pos_src = ii;
1151                       break;
1152                     }
1153                 }
1154               if (jj >= dst_l)  /* The location has not been found.  */
1155                 {
1156                   location_chain new_node;
1157
1158                   /* Copy the location from SRC.  */
1159                   new_node = pool_alloc (loc_chain_pool);
1160                   new_node->loc = node->loc;
1161                   vui[n].lc = new_node;
1162                   vui[n].pos_src = ii;
1163                   vui[n].pos_dst = src_l + dst_l;
1164                   n++;
1165                 }
1166             }
1167
1168           for (ii = 0; ii < src_l + dst_l; ii++)
1169             vui[ii].pos = vui[ii].pos_src + vui[ii].pos_dst;
1170
1171           qsort (vui, n, sizeof (struct variable_union_info),
1172                  variable_union_info_cmp_pos);
1173
1174           /* Reconnect the nodes in sorted order.  */
1175           for (ii = 1; ii < n; ii++)
1176             vui[ii - 1].lc->next = vui[ii].lc;
1177           vui[n - 1].lc->next = NULL;
1178
1179           dst->var_part[k].loc_chain = vui[0].lc;
1180           dst->var_part[k].offset = dst->var_part[j].offset;
1181
1182           free (vui);
1183           i--;
1184           j--;
1185         }
1186       else if ((i >= 0 && j >= 0
1187                 && src->var_part[i].offset < dst->var_part[j].offset)
1188                || i < 0)
1189         {
1190           dst->var_part[k] = dst->var_part[j];
1191           j--;
1192         }
1193       else if ((i >= 0 && j >= 0
1194                 && src->var_part[i].offset > dst->var_part[j].offset)
1195                || j < 0)
1196         {
1197           location_chain *nextp;
1198
1199           /* Copy the chain from SRC.  */
1200           nextp = &dst->var_part[k].loc_chain;
1201           for (node = src->var_part[i].loc_chain; node; node = node->next)
1202             {
1203               location_chain new_lc;
1204
1205               new_lc = pool_alloc (loc_chain_pool);
1206               new_lc->next = NULL;
1207               new_lc->loc = node->loc;
1208
1209               *nextp = new_lc;
1210               nextp = &new_lc->next;
1211             }
1212
1213           dst->var_part[k].offset = src->var_part[i].offset;
1214           i--;
1215         }
1216
1217       /* We are at the basic block boundary when computing union
1218          so set the CUR_LOC to be the first element of the chain.  */
1219       if (dst->var_part[k].loc_chain)
1220         dst->var_part[k].cur_loc = dst->var_part[k].loc_chain->loc;
1221       else
1222         dst->var_part[k].cur_loc = NULL;
1223     }
1224
1225   /* Continue traversing the hash table.  */
1226   return 1;
1227 }
1228
1229 /* Compute union of dataflow sets SRC and DST and store it to DST.  */
1230
1231 static void
1232 dataflow_set_union (dataflow_set *dst, dataflow_set *src)
1233 {
1234   int i;
1235
1236   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1237     attrs_list_union (&dst->regs[i], src->regs[i]);
1238
1239   htab_traverse (src->vars, variable_union, dst);
1240 }
1241
1242 /* Flag whether two dataflow sets being compared contain different data.  */
1243 static bool
1244 dataflow_set_different_value;
1245
1246 static bool
1247 variable_part_different_p (variable_part *vp1, variable_part *vp2)
1248 {
1249   location_chain lc1, lc2;
1250
1251   for (lc1 = vp1->loc_chain; lc1; lc1 = lc1->next)
1252     {
1253       for (lc2 = vp2->loc_chain; lc2; lc2 = lc2->next)
1254         {
1255           if (REG_P (lc1->loc) && REG_P (lc2->loc))
1256             {
1257               if (REGNO (lc1->loc) == REGNO (lc2->loc))
1258                 break;
1259             }
1260           if (rtx_equal_p (lc1->loc, lc2->loc))
1261             break;
1262         }
1263       if (!lc2)
1264         return true;
1265     }
1266   return false;
1267 }
1268
1269 /* Return true if variables VAR1 and VAR2 are different.
1270    If COMPARE_CURRENT_LOCATION is true compare also the cur_loc of each
1271    variable part.  */
1272
1273 static bool
1274 variable_different_p (variable var1, variable var2,
1275                       bool compare_current_location)
1276 {
1277   int i;
1278
1279   if (var1 == var2)
1280     return false;
1281
1282   if (var1->n_var_parts != var2->n_var_parts)
1283     return true;
1284
1285   for (i = 0; i < var1->n_var_parts; i++)
1286     {
1287       if (var1->var_part[i].offset != var2->var_part[i].offset)
1288         return true;
1289       if (compare_current_location)
1290         {
1291           if (!((REG_P (var1->var_part[i].cur_loc)
1292                  && REG_P (var2->var_part[i].cur_loc)
1293                  && (REGNO (var1->var_part[i].cur_loc)
1294                      == REGNO (var2->var_part[i].cur_loc)))
1295                 || rtx_equal_p (var1->var_part[i].cur_loc,
1296                                 var2->var_part[i].cur_loc)))
1297             return true;
1298         }
1299       if (variable_part_different_p (&var1->var_part[i], &var2->var_part[i]))
1300         return true;
1301       if (variable_part_different_p (&var2->var_part[i], &var1->var_part[i]))
1302         return true;
1303     }
1304   return false;
1305 }
1306
1307 /* Compare variable *SLOT with the same variable in hash table DATA
1308    and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */
1309
1310 static int
1311 dataflow_set_different_1 (void **slot, void *data)
1312 {
1313   htab_t htab = (htab_t) data;
1314   variable var1, var2;
1315
1316   var1 = *(variable *) slot;
1317   var2 = htab_find_with_hash (htab, var1->decl,
1318                               VARIABLE_HASH_VAL (var1->decl));
1319   if (!var2)
1320     {
1321       dataflow_set_different_value = true;
1322
1323       /* Stop traversing the hash table.  */
1324       return 0;
1325     }
1326
1327   if (variable_different_p (var1, var2, false))
1328     {
1329       dataflow_set_different_value = true;
1330
1331       /* Stop traversing the hash table.  */
1332       return 0;
1333     }
1334
1335   /* Continue traversing the hash table.  */
1336   return 1;
1337 }
1338
1339 /* Compare variable *SLOT with the same variable in hash table DATA
1340    and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */
1341
1342 static int
1343 dataflow_set_different_2 (void **slot, void *data)
1344 {
1345   htab_t htab = (htab_t) data;
1346   variable var1, var2;
1347
1348   var1 = *(variable *) slot;
1349   var2 = htab_find_with_hash (htab, var1->decl,
1350                               VARIABLE_HASH_VAL (var1->decl));
1351   if (!var2)
1352     {
1353       dataflow_set_different_value = true;
1354
1355       /* Stop traversing the hash table.  */
1356       return 0;
1357     }
1358
1359 #ifdef ENABLE_CHECKING
1360   /* If both variables are defined they have been already checked for
1361      equivalence.  */
1362   if (variable_different_p (var1, var2, false))
1363     abort ();
1364 #endif
1365
1366   /* Continue traversing the hash table.  */
1367   return 1;
1368 }
1369
1370 /* Return true if dataflow sets OLD_SET and NEW_SET differ.  */
1371
1372 static bool
1373 dataflow_set_different (dataflow_set *old_set, dataflow_set *new_set)
1374 {
1375   dataflow_set_different_value = false;
1376
1377   htab_traverse (old_set->vars, dataflow_set_different_1, new_set->vars);
1378   if (!dataflow_set_different_value)
1379     {
1380       /* We have compared the variables which are in both hash tables
1381          so now only check whether there are some variables in NEW_SET->VARS
1382          which are not in OLD_SET->VARS.  */
1383       htab_traverse (new_set->vars, dataflow_set_different_2, old_set->vars);
1384     }
1385   return dataflow_set_different_value;
1386 }
1387
1388 /* Free the contents of dataflow set SET.  */
1389
1390 static void
1391 dataflow_set_destroy (dataflow_set *set)
1392 {
1393   int i;
1394
1395   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1396     attrs_list_clear (&set->regs[i]);
1397
1398   htab_delete (set->vars);
1399   set->vars = NULL;
1400 }
1401
1402 /* Return true if RTL X contains a SYMBOL_REF.  */
1403
1404 static bool
1405 contains_symbol_ref (rtx x)
1406 {
1407   const char *fmt;
1408   RTX_CODE code;
1409   int i;
1410
1411   if (!x)
1412     return false;
1413
1414   code = GET_CODE (x);
1415   if (code == SYMBOL_REF)
1416     return true;
1417
1418   fmt = GET_RTX_FORMAT (code);
1419   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1420     {
1421       if (fmt[i] == 'e')
1422         {
1423           if (contains_symbol_ref (XEXP (x, i)))
1424             return true;
1425         }
1426       else if (fmt[i] == 'E')
1427         {
1428           int j;
1429           for (j = 0; j < XVECLEN (x, i); j++)
1430             if (contains_symbol_ref (XVECEXP (x, i, j)))
1431               return true;
1432         }
1433     }
1434
1435   return false;
1436 }
1437
1438 /* Shall EXPR be tracked?  */
1439
1440 static bool
1441 track_expr_p (tree expr)
1442 {
1443   rtx decl_rtl;
1444
1445   /* If EXPR is not a parameter or a variable do not track it.  */
1446   if (TREE_CODE (expr) != VAR_DECL && TREE_CODE (expr) != PARM_DECL)
1447     return 0;
1448
1449   /* It also must have a name...  */
1450   if (!DECL_NAME (expr))
1451     return 0;
1452
1453   /* ... and a RTL assigned to it.  */
1454   decl_rtl = DECL_RTL_IF_SET (expr);
1455   if (!decl_rtl)
1456     return 0;
1457
1458   /* Do not track EXPR if it should be ignored for debugging purposes.  */
1459   if (DECL_IGNORED_P (expr))
1460     return 0;
1461
1462   /* Do not track global variables until we are able to emit correct location
1463      list for them.  */
1464   if (TREE_STATIC (expr))
1465     return 0;
1466
1467   /* When the EXPR is a DECL for alias of some variable (see example)
1468      the TREE_STATIC flag is not used.  Disable tracking all DECLs whose
1469      DECL_RTL contains SYMBOL_REF.
1470
1471      Example:
1472      extern char **_dl_argv_internal __attribute__ ((alias ("_dl_argv")));
1473      char **_dl_argv;
1474   */
1475   if (MEM_P (decl_rtl)
1476       && contains_symbol_ref (XEXP (decl_rtl, 0)))
1477     return 0;
1478
1479   /* If RTX is a memory it should not be very large (because it would be
1480      an array or struct).  */
1481   if (MEM_P (decl_rtl))
1482     {
1483       /* Do not track structures and arrays.  */
1484       if (GET_MODE (decl_rtl) == BLKmode)
1485         return 0;
1486       if (MEM_SIZE (decl_rtl)
1487           && INTVAL (MEM_SIZE (decl_rtl)) > MAX_VAR_PARTS)
1488         return 0;
1489     }
1490
1491   return 1;
1492 }
1493
1494 /* Count uses (register and memory references) LOC which will be tracked.
1495    INSN is instruction which the LOC is part of.  */
1496
1497 static int
1498 count_uses (rtx *loc, void *insn)
1499 {
1500   basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1501
1502   if (REG_P (*loc))
1503     {
1504 #ifdef ENABLE_CHECKING
1505         if (REGNO (*loc) >= FIRST_PSEUDO_REGISTER)
1506           abort ();
1507 #endif
1508         VTI (bb)->n_mos++;
1509     }
1510   else if (MEM_P (*loc)
1511            && MEM_EXPR (*loc)
1512            && track_expr_p (MEM_EXPR (*loc)))
1513     {
1514           VTI (bb)->n_mos++;
1515     }
1516
1517   return 0;
1518 }
1519
1520 /* Helper function for finding all uses of REG/MEM in X in insn INSN.  */
1521
1522 static void
1523 count_uses_1 (rtx *x, void *insn)
1524 {
1525   for_each_rtx (x, count_uses, insn);
1526 }
1527
1528 /* Count stores (register and memory references) LOC which will be tracked.
1529    INSN is instruction which the LOC is part of.  */
1530
1531 static void
1532 count_stores (rtx loc, rtx expr ATTRIBUTE_UNUSED, void *insn)
1533 {
1534   count_uses (&loc, insn);
1535 }
1536
1537 /* Add uses (register and memory references) LOC which will be tracked
1538    to VTI (bb)->mos.  INSN is instruction which the LOC is part of.  */
1539
1540 static int
1541 add_uses (rtx *loc, void *insn)
1542 {
1543   if (REG_P (*loc))
1544     {
1545       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1546       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1547
1548       mo->type = ((REG_EXPR (*loc) && track_expr_p (REG_EXPR (*loc)))
1549                   ? MO_USE : MO_USE_NO_VAR);
1550       mo->u.loc = *loc;
1551       mo->insn = (rtx) insn;
1552     }
1553   else if (MEM_P (*loc)
1554            && MEM_EXPR (*loc)
1555            && track_expr_p (MEM_EXPR (*loc)))
1556     {
1557       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1558       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1559
1560       mo->type = MO_USE;
1561       mo->u.loc = *loc;
1562       mo->insn = (rtx) insn;
1563     }
1564
1565   return 0;
1566 }
1567
1568 /* Helper function for finding all uses of REG/MEM in X in insn INSN.  */
1569
1570 static void
1571 add_uses_1 (rtx *x, void *insn)
1572 {
1573   for_each_rtx (x, add_uses, insn);
1574 }
1575
1576 /* Add stores (register and memory references) LOC which will be tracked
1577    to VTI (bb)->mos. EXPR is the RTL expression containing the store.
1578    INSN is instruction which the LOC is part of.  */
1579
1580 static void
1581 add_stores (rtx loc, rtx expr, void *insn)
1582 {
1583   if (REG_P (loc))
1584     {
1585       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1586       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1587
1588       mo->type = ((GET_CODE (expr) != CLOBBER && REG_EXPR (loc)
1589                    && track_expr_p (REG_EXPR (loc)))
1590                   ? MO_SET : MO_CLOBBER);
1591       mo->u.loc = loc;
1592       mo->insn = (rtx) insn;
1593     }
1594   else if (MEM_P (loc)
1595            && MEM_EXPR (loc)
1596            && track_expr_p (MEM_EXPR (loc)))
1597     {
1598       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1599       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1600
1601       mo->type = GET_CODE (expr) == CLOBBER ? MO_CLOBBER : MO_SET;
1602       mo->u.loc = loc;
1603       mo->insn = (rtx) insn;
1604     }
1605 }
1606
1607 /* Compute the changes of variable locations in the basic block BB.  */
1608
1609 static bool
1610 compute_bb_dataflow (basic_block bb)
1611 {
1612   int i, n, r;
1613   bool changed;
1614   dataflow_set old_out;
1615   dataflow_set *in = &VTI (bb)->in;
1616   dataflow_set *out = &VTI (bb)->out;
1617
1618   dataflow_set_init (&old_out, htab_elements (VTI (bb)->out.vars) + 3);
1619   dataflow_set_copy (&old_out, out);
1620   dataflow_set_copy (out, in);
1621
1622   n = VTI (bb)->n_mos;
1623   for (i = 0; i < n; i++)
1624     {
1625       switch (VTI (bb)->mos[i].type)
1626         {
1627           case MO_CALL:
1628             for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
1629               if (TEST_HARD_REG_BIT (call_used_reg_set, r))
1630                 var_regno_delete (out, r);
1631             break;
1632
1633           case MO_USE:
1634           case MO_SET:
1635             {
1636               rtx loc = VTI (bb)->mos[i].u.loc;
1637
1638               if (REG_P (loc))
1639                 var_reg_delete_and_set (out, loc);
1640               else if (MEM_P (loc))
1641                 var_mem_delete_and_set (out, loc);
1642             }
1643             break;
1644
1645           case MO_USE_NO_VAR:
1646           case MO_CLOBBER:
1647             {
1648               rtx loc = VTI (bb)->mos[i].u.loc;
1649
1650               if (REG_P (loc))
1651                 var_reg_delete (out, loc);
1652               else if (MEM_P (loc))
1653                 var_mem_delete (out, loc);
1654             }
1655             break;
1656
1657           case MO_ADJUST:
1658             {
1659               rtx base;
1660
1661               out->stack_adjust += VTI (bb)->mos[i].u.adjust;
1662               base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
1663                                                         out->stack_adjust));
1664               set_frame_base_location (out, base);
1665             }
1666             break;
1667         }
1668     }
1669
1670   changed = dataflow_set_different (&old_out, out);
1671   dataflow_set_destroy (&old_out);
1672   return changed;
1673 }
1674
1675 /* Find the locations of variables in the whole function.  */
1676
1677 static void
1678 vt_find_locations (void)
1679 {
1680   fibheap_t worklist, pending, fibheap_swap;
1681   sbitmap visited, in_worklist, in_pending, sbitmap_swap;
1682   basic_block bb;
1683   edge e;
1684   int *bb_order;
1685   int *rc_order;
1686   int i;
1687
1688   /* Compute reverse completion order of depth first search of the CFG
1689      so that the data-flow runs faster.  */
1690   rc_order = xmalloc (n_basic_blocks * sizeof (int));
1691   bb_order = xmalloc (last_basic_block * sizeof (int));
1692   flow_depth_first_order_compute (NULL, rc_order);
1693   for (i = 0; i < n_basic_blocks; i++)
1694     bb_order[rc_order[i]] = i;
1695   free (rc_order);
1696
1697   worklist = fibheap_new ();
1698   pending = fibheap_new ();
1699   visited = sbitmap_alloc (last_basic_block);
1700   in_worklist = sbitmap_alloc (last_basic_block);
1701   in_pending = sbitmap_alloc (last_basic_block);
1702   sbitmap_zero (in_worklist);
1703
1704   FOR_EACH_BB (bb)
1705     fibheap_insert (pending, bb_order[bb->index], bb);
1706   sbitmap_ones (in_pending);
1707
1708   while (!fibheap_empty (pending))
1709     {
1710       fibheap_swap = pending;
1711       pending = worklist;
1712       worklist = fibheap_swap;
1713       sbitmap_swap = in_pending;
1714       in_pending = in_worklist;
1715       in_worklist = sbitmap_swap;
1716
1717       sbitmap_zero (visited);
1718
1719       while (!fibheap_empty (worklist))
1720         {
1721           bb = fibheap_extract_min (worklist);
1722           RESET_BIT (in_worklist, bb->index);
1723           if (!TEST_BIT (visited, bb->index))
1724             {
1725               bool changed;
1726               edge_iterator ei;
1727
1728               SET_BIT (visited, bb->index);
1729
1730               /* Calculate the IN set as union of predecessor OUT sets.  */
1731               dataflow_set_clear (&VTI (bb)->in);
1732               FOR_EACH_EDGE (e, ei, bb->preds)
1733                 {
1734                   dataflow_set_union (&VTI (bb)->in, &VTI (e->src)->out);
1735                 }
1736
1737               changed = compute_bb_dataflow (bb);
1738               if (changed)
1739                 {
1740                   FOR_EACH_EDGE (e, ei, bb->succs)
1741                     {
1742                       if (e->dest == EXIT_BLOCK_PTR)
1743                         continue;
1744
1745                       if (e->dest == bb)
1746                         continue;
1747
1748                       if (TEST_BIT (visited, e->dest->index))
1749                         {
1750                           if (!TEST_BIT (in_pending, e->dest->index))
1751                             {
1752                               /* Send E->DEST to next round.  */
1753                               SET_BIT (in_pending, e->dest->index);
1754                               fibheap_insert (pending,
1755                                               bb_order[e->dest->index],
1756                                               e->dest);
1757                             }
1758                         }
1759                       else if (!TEST_BIT (in_worklist, e->dest->index))
1760                         {
1761                           /* Add E->DEST to current round.  */
1762                           SET_BIT (in_worklist, e->dest->index);
1763                           fibheap_insert (worklist, bb_order[e->dest->index],
1764                                           e->dest);
1765                         }
1766                     }
1767                 }
1768             }
1769         }
1770     }
1771
1772   free (bb_order);
1773   fibheap_delete (worklist);
1774   fibheap_delete (pending);
1775   sbitmap_free (visited);
1776   sbitmap_free (in_worklist);
1777   sbitmap_free (in_pending);
1778 }
1779
1780 /* Print the content of the LIST to dump file.  */
1781
1782 static void
1783 dump_attrs_list (attrs list)
1784 {
1785   for (; list; list = list->next)
1786     {
1787       print_mem_expr (dump_file, list->decl);
1788       fprintf (dump_file, "+");
1789       fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, list->offset);
1790     }
1791   fprintf (dump_file, "\n");
1792 }
1793
1794 /* Print the information about variable *SLOT to dump file.  */
1795
1796 static int
1797 dump_variable (void **slot, void *data ATTRIBUTE_UNUSED)
1798 {
1799   variable var = *(variable *) slot;
1800   int i;
1801   location_chain node;
1802
1803   fprintf (dump_file, "  name: %s\n",
1804            IDENTIFIER_POINTER (DECL_NAME (var->decl)));
1805   for (i = 0; i < var->n_var_parts; i++)
1806     {
1807       fprintf (dump_file, "    offset %ld\n",
1808                (long) var->var_part[i].offset);
1809       for (node = var->var_part[i].loc_chain; node; node = node->next)
1810         {
1811           fprintf (dump_file, "      ");
1812           print_rtl_single (dump_file, node->loc);
1813         }
1814     }
1815
1816   /* Continue traversing the hash table.  */
1817   return 1;
1818 }
1819
1820 /* Print the information about variables from hash table VARS to dump file.  */
1821
1822 static void
1823 dump_vars (htab_t vars)
1824 {
1825   if (htab_elements (vars) > 0)
1826     {
1827       fprintf (dump_file, "Variables:\n");
1828       htab_traverse (vars, dump_variable, NULL);
1829     }
1830 }
1831
1832 /* Print the dataflow set SET to dump file.  */
1833
1834 static void
1835 dump_dataflow_set (dataflow_set *set)
1836 {
1837   int i;
1838
1839   fprintf (dump_file, "Stack adjustment: ");
1840   fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, set->stack_adjust);
1841   fprintf (dump_file, "\n");
1842   for (i = 1; i < FIRST_PSEUDO_REGISTER; i++)
1843     {
1844       if (set->regs[i])
1845         {
1846           fprintf (dump_file, "Reg %d:", i);
1847           dump_attrs_list (set->regs[i]);
1848         }
1849     }
1850   dump_vars (set->vars);
1851   fprintf (dump_file, "\n");
1852 }
1853
1854 /* Print the IN and OUT sets for each basic block to dump file.  */
1855
1856 static void
1857 dump_dataflow_sets (void)
1858 {
1859   basic_block bb;
1860
1861   FOR_EACH_BB (bb)
1862     {
1863       fprintf (dump_file, "\nBasic block %d:\n", bb->index);
1864       fprintf (dump_file, "IN:\n");
1865       dump_dataflow_set (&VTI (bb)->in);
1866       fprintf (dump_file, "OUT:\n");
1867       dump_dataflow_set (&VTI (bb)->out);
1868     }
1869 }
1870
1871 /* Add variable VAR to the hash table of changed variables and
1872    if it has no locations delete it from hash table HTAB.  */
1873
1874 static void
1875 variable_was_changed (variable var, htab_t htab)
1876 {
1877   hashval_t hash = VARIABLE_HASH_VAL (var->decl);
1878
1879   if (emit_notes)
1880     {
1881       variable *slot;
1882
1883       slot = (variable *) htab_find_slot_with_hash (changed_variables,
1884                                                     var->decl, hash, INSERT);
1885
1886       if (htab && var->n_var_parts == 0)
1887         {
1888           variable empty_var;
1889           void **old;
1890
1891           empty_var = pool_alloc (var_pool);
1892           empty_var->decl = var->decl;
1893           empty_var->refcount = 1;
1894           empty_var->n_var_parts = 0;
1895           *slot = empty_var;
1896
1897           old = htab_find_slot_with_hash (htab, var->decl, hash,
1898                                           NO_INSERT);
1899           if (old)
1900             htab_clear_slot (htab, old);
1901         }
1902       else
1903         {
1904           *slot = var;
1905         }
1906     }
1907   else
1908     {
1909 #ifdef ENABLE_CHECKING
1910       if (!htab)
1911         abort ();
1912 #endif
1913       if (var->n_var_parts == 0)
1914         {
1915           void **slot = htab_find_slot_with_hash (htab, var->decl, hash,
1916                                                   NO_INSERT);
1917           if (slot)
1918             htab_clear_slot (htab, slot);
1919         }
1920     }
1921 }
1922
1923 /* Set the location of frame_base_decl to LOC in dataflow set SET.  This
1924    function expects that frame_base_decl has already one location for offset 0
1925    in the variable table.  */
1926
1927 static void
1928 set_frame_base_location (dataflow_set *set, rtx loc)
1929 {
1930   variable var;
1931
1932   var = htab_find_with_hash (set->vars, frame_base_decl,
1933                              VARIABLE_HASH_VAL (frame_base_decl));
1934 #ifdef ENABLE_CHECKING
1935   if (!var)
1936     abort ();
1937   if (var->n_var_parts != 1)
1938     abort ();
1939   if (var->var_part[0].offset != 0)
1940     abort ();
1941   if (!var->var_part[0].loc_chain)
1942     abort ();
1943 #endif
1944
1945   /* If frame_base_decl is shared unshare it first.  */
1946   if (var->refcount > 1)
1947     var = unshare_variable (set, var);
1948
1949   var->var_part[0].loc_chain->loc = loc;
1950   var->var_part[0].cur_loc = loc;
1951   variable_was_changed (var, set->vars);
1952 }
1953
1954 /* Set the part of variable's location in the dataflow set SET.  The variable
1955    part is specified by variable's declaration DECL and offset OFFSET and the
1956    part's location by LOC.  */
1957
1958 static void
1959 set_variable_part (dataflow_set *set, rtx loc, tree decl, HOST_WIDE_INT offset)
1960 {
1961   int pos, low, high;
1962   location_chain node, next;
1963   location_chain *nextp;
1964   variable var;
1965   void **slot;
1966
1967   slot = htab_find_slot_with_hash (set->vars, decl,
1968                                    VARIABLE_HASH_VAL (decl), INSERT);
1969   if (!*slot)
1970     {
1971       /* Create new variable information.  */
1972       var = pool_alloc (var_pool);
1973       var->decl = decl;
1974       var->refcount = 1;
1975       var->n_var_parts = 1;
1976       var->var_part[0].offset = offset;
1977       var->var_part[0].loc_chain = NULL;
1978       var->var_part[0].cur_loc = NULL;
1979       *slot = var;
1980       pos = 0;
1981     }
1982   else
1983     {
1984       var = (variable) *slot;
1985
1986       /* Find the location part.  */
1987       low = 0;
1988       high = var->n_var_parts;
1989       while (low != high)
1990         {
1991           pos = (low + high) / 2;
1992           if (var->var_part[pos].offset < offset)
1993             low = pos + 1;
1994           else
1995             high = pos;
1996         }
1997       pos = low;
1998
1999       if (pos < var->n_var_parts && var->var_part[pos].offset == offset)
2000         {
2001           node = var->var_part[pos].loc_chain;
2002
2003           if (node
2004               && ((REG_P (node->loc) && REG_P (loc)
2005                    && REGNO (node->loc) == REGNO (loc))
2006                   || rtx_equal_p (node->loc, loc)))
2007             {
2008               /* LOC is in the beginning of the chain so we have nothing
2009                  to do.  */
2010               return;
2011             }
2012           else
2013             {
2014               /* We have to make a copy of a shared variable.  */
2015               if (var->refcount > 1)
2016                 var = unshare_variable (set, var);
2017             }
2018         }
2019       else
2020         {
2021           /* We have not found the location part, new one will be created.  */
2022
2023           /* We have to make a copy of the shared variable.  */
2024           if (var->refcount > 1)
2025             var = unshare_variable (set, var);
2026
2027 #ifdef ENABLE_CHECKING
2028           /* We track only variables whose size is <= MAX_VAR_PARTS bytes
2029              thus there are at most MAX_VAR_PARTS different offsets.  */
2030           if (var->n_var_parts >= MAX_VAR_PARTS)
2031             abort ();
2032 #endif
2033
2034           /* We have to move the elements of array starting at index low to the
2035              next position.  */
2036           for (high = var->n_var_parts; high > low; high--)
2037             var->var_part[high] = var->var_part[high - 1];
2038
2039           var->n_var_parts++;
2040           var->var_part[pos].offset = offset;
2041           var->var_part[pos].loc_chain = NULL;
2042           var->var_part[pos].cur_loc = NULL;
2043         }
2044     }
2045
2046   /* Delete the location from the list.  */
2047   nextp = &var->var_part[pos].loc_chain;
2048   for (node = var->var_part[pos].loc_chain; node; node = next)
2049     {
2050       next = node->next;
2051       if ((REG_P (node->loc) && REG_P (loc)
2052            && REGNO (node->loc) == REGNO (loc))
2053           || rtx_equal_p (node->loc, loc))
2054         {
2055           pool_free (loc_chain_pool, node);
2056           *nextp = next;
2057           break;
2058         }
2059       else
2060         nextp = &node->next;
2061     }
2062
2063   /* Add the location to the beginning.  */
2064   node = pool_alloc (loc_chain_pool);
2065   node->loc = loc;
2066   node->next = var->var_part[pos].loc_chain;
2067   var->var_part[pos].loc_chain = node;
2068
2069   /* If no location was emitted do so.  */
2070   if (var->var_part[pos].cur_loc == NULL)
2071     {
2072       var->var_part[pos].cur_loc = loc;
2073       variable_was_changed (var, set->vars);
2074     }
2075 }
2076
2077 /* Delete the part of variable's location from dataflow set SET.  The variable
2078    part is specified by variable's declaration DECL and offset OFFSET and the
2079    part's location by LOC.  */
2080
2081 static void
2082 delete_variable_part (dataflow_set *set, rtx loc, tree decl,
2083                       HOST_WIDE_INT offset)
2084 {
2085   int pos, low, high;
2086   void **slot;
2087
2088   slot = htab_find_slot_with_hash (set->vars, decl, VARIABLE_HASH_VAL (decl),
2089                                    NO_INSERT);
2090   if (slot)
2091     {
2092       variable var = (variable) *slot;
2093
2094       /* Find the location part.  */
2095       low = 0;
2096       high = var->n_var_parts;
2097       while (low != high)
2098         {
2099           pos = (low + high) / 2;
2100           if (var->var_part[pos].offset < offset)
2101             low = pos + 1;
2102           else
2103             high = pos;
2104         }
2105       pos = low;
2106
2107       if (pos < var->n_var_parts && var->var_part[pos].offset == offset)
2108         {
2109           location_chain node, next;
2110           location_chain *nextp;
2111           bool changed;
2112
2113           if (var->refcount > 1)
2114             {
2115               /* If the variable contains the location part we have to
2116                  make a copy of the variable.  */
2117               for (node = var->var_part[pos].loc_chain; node;
2118                    node = node->next)
2119                 {
2120                   if ((REG_P (node->loc) && REG_P (loc)
2121                        && REGNO (node->loc) == REGNO (loc))
2122                       || rtx_equal_p (node->loc, loc))
2123                     {
2124                       var = unshare_variable (set, var);
2125                       break;
2126                     }
2127                 }
2128             }
2129
2130           /* Delete the location part.  */
2131           nextp = &var->var_part[pos].loc_chain;
2132           for (node = *nextp; node; node = next)
2133             {
2134               next = node->next;
2135               if ((REG_P (node->loc) && REG_P (loc)
2136                    && REGNO (node->loc) == REGNO (loc))
2137                   || rtx_equal_p (node->loc, loc))
2138                 {
2139                   pool_free (loc_chain_pool, node);
2140                   *nextp = next;
2141                   break;
2142                 }
2143               else
2144                 nextp = &node->next;
2145             }
2146
2147           /* If we have deleted the location which was last emitted
2148              we have to emit new location so add the variable to set
2149              of changed variables.  */
2150           if (var->var_part[pos].cur_loc
2151               && ((REG_P (loc)
2152                    && REG_P (var->var_part[pos].cur_loc)
2153                    && REGNO (loc) == REGNO (var->var_part[pos].cur_loc))
2154                   || rtx_equal_p (loc, var->var_part[pos].cur_loc)))
2155             {
2156               changed = true;
2157               if (var->var_part[pos].loc_chain)
2158                 var->var_part[pos].cur_loc = var->var_part[pos].loc_chain->loc;
2159             }
2160           else
2161             changed = false;
2162
2163           if (var->var_part[pos].loc_chain == NULL)
2164             {
2165               var->n_var_parts--;
2166               while (pos < var->n_var_parts)
2167                 {
2168                   var->var_part[pos] = var->var_part[pos + 1];
2169                   pos++;
2170                 }
2171             }
2172           if (changed)
2173               variable_was_changed (var, set->vars);
2174         }
2175     }
2176 }
2177
2178 /* Emit the NOTE_INSN_VAR_LOCATION for variable *VARP.  DATA contains
2179    additional parameters: WHERE specifies whether the note shall be emitted
2180    before of after instruction INSN.  */
2181
2182 static int
2183 emit_note_insn_var_location (void **varp, void *data)
2184 {
2185   variable var = *(variable *) varp;
2186   rtx insn = ((emit_note_data *)data)->insn;
2187   enum emit_note_where where = ((emit_note_data *)data)->where;
2188   rtx note;
2189   int i;
2190   bool complete;
2191   HOST_WIDE_INT last_limit;
2192   tree type_size_unit;
2193
2194 #ifdef ENABLE_CHECKING
2195   if (!var->decl)
2196     abort ();
2197 #endif
2198
2199   complete = true;
2200   last_limit = 0;
2201   for (i = 0; i < var->n_var_parts; i++)
2202     {
2203       if (last_limit < var->var_part[i].offset)
2204         {
2205           complete = false;
2206           break;
2207         }
2208       last_limit
2209         = (var->var_part[i].offset
2210            + GET_MODE_SIZE (GET_MODE (var->var_part[i].loc_chain->loc)));
2211     }
2212   type_size_unit = TYPE_SIZE_UNIT (TREE_TYPE (var->decl));
2213   if ((unsigned HOST_WIDE_INT) last_limit < TREE_INT_CST_LOW (type_size_unit))
2214     complete = false;
2215
2216   if (where == EMIT_NOTE_AFTER_INSN)
2217     note = emit_note_after (NOTE_INSN_VAR_LOCATION, insn);
2218   else
2219     note = emit_note_before (NOTE_INSN_VAR_LOCATION, insn);
2220
2221   if (!complete)
2222     {
2223       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2224                                                        NULL_RTX);
2225     }
2226   else if (var->n_var_parts == 1)
2227     {
2228       rtx expr_list
2229         = gen_rtx_EXPR_LIST (VOIDmode,
2230                              var->var_part[0].loc_chain->loc,
2231                              GEN_INT (var->var_part[0].offset));
2232
2233       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2234                                                        expr_list);
2235     }
2236   else if (var->n_var_parts)
2237     {
2238       rtx argp[MAX_VAR_PARTS];
2239       rtx parallel;
2240
2241       for (i = 0; i < var->n_var_parts; i++)
2242         argp[i] = gen_rtx_EXPR_LIST (VOIDmode, var->var_part[i].loc_chain->loc,
2243                                      GEN_INT (var->var_part[i].offset));
2244       parallel = gen_rtx_PARALLEL (VOIDmode,
2245                                    gen_rtvec_v (var->n_var_parts, argp));
2246       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2247                                                        parallel);
2248     }
2249
2250   htab_clear_slot (changed_variables, varp);
2251
2252   /* When there are no location parts the variable has been already
2253      removed from hash table and a new empty variable was created.
2254      Free the empty variable.  */
2255   if (var->n_var_parts == 0)
2256     {
2257       pool_free (var_pool, var);
2258     }
2259
2260   /* Continue traversing the hash table.  */
2261   return 1;
2262 }
2263
2264 /* Emit NOTE_INSN_VAR_LOCATION note for each variable from a chain
2265    CHANGED_VARIABLES and delete this chain.  WHERE specifies whether the notes
2266    shall be emitted before of after instruction INSN.  */
2267
2268 static void
2269 emit_notes_for_changes (rtx insn, enum emit_note_where where)
2270 {
2271   emit_note_data data;
2272
2273   data.insn = insn;
2274   data.where = where;
2275   htab_traverse (changed_variables, emit_note_insn_var_location, &data);
2276 }
2277
2278 /* Add variable *SLOT to the chain CHANGED_VARIABLES if it differs from the
2279    same variable in hash table DATA or is not there at all.  */
2280
2281 static int
2282 emit_notes_for_differences_1 (void **slot, void *data)
2283 {
2284   htab_t new_vars = (htab_t) data;
2285   variable old_var, new_var;
2286
2287   old_var = *(variable *) slot;
2288   new_var = htab_find_with_hash (new_vars, old_var->decl,
2289                                  VARIABLE_HASH_VAL (old_var->decl));
2290
2291   if (!new_var)
2292     {
2293       /* Variable has disappeared.  */
2294       variable empty_var;
2295
2296       empty_var = pool_alloc (var_pool);
2297       empty_var->decl = old_var->decl;
2298       empty_var->refcount = 1;
2299       empty_var->n_var_parts = 0;
2300       variable_was_changed (empty_var, NULL);
2301     }
2302   else if (variable_different_p (old_var, new_var, true))
2303     {
2304       variable_was_changed (new_var, NULL);
2305     }
2306
2307   /* Continue traversing the hash table.  */
2308   return 1;
2309 }
2310
2311 /* Add variable *SLOT to the chain CHANGED_VARIABLES if it is not in hash
2312    table DATA.  */
2313
2314 static int
2315 emit_notes_for_differences_2 (void **slot, void *data)
2316 {
2317   htab_t old_vars = (htab_t) data;
2318   variable old_var, new_var;
2319
2320   new_var = *(variable *) slot;
2321   old_var = htab_find_with_hash (old_vars, new_var->decl,
2322                                  VARIABLE_HASH_VAL (new_var->decl));
2323   if (!old_var)
2324     {
2325       /* Variable has appeared.  */
2326       variable_was_changed (new_var, NULL);
2327     }
2328
2329   /* Continue traversing the hash table.  */
2330   return 1;
2331 }
2332
2333 /* Emit notes before INSN for differences between dataflow sets OLD_SET and
2334    NEW_SET.  */
2335
2336 static void
2337 emit_notes_for_differences (rtx insn, dataflow_set *old_set,
2338                             dataflow_set *new_set)
2339 {
2340   htab_traverse (old_set->vars, emit_notes_for_differences_1, new_set->vars);
2341   htab_traverse (new_set->vars, emit_notes_for_differences_2, old_set->vars);
2342   emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2343 }
2344
2345 /* Emit the notes for changes of location parts in the basic block BB.  */
2346
2347 static void
2348 emit_notes_in_bb (basic_block bb)
2349 {
2350   int i;
2351   dataflow_set set;
2352
2353   dataflow_set_init (&set, htab_elements (VTI (bb)->in.vars) + 3);
2354   dataflow_set_copy (&set, &VTI (bb)->in);
2355
2356   for (i = 0; i < VTI (bb)->n_mos; i++)
2357     {
2358       rtx insn = VTI (bb)->mos[i].insn;
2359
2360       switch (VTI (bb)->mos[i].type)
2361         {
2362           case MO_CALL:
2363             {
2364               int r;
2365
2366               for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
2367                 if (TEST_HARD_REG_BIT (call_used_reg_set, r))
2368                   {
2369                     var_regno_delete (&set, r);
2370                   }
2371               emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2372             }
2373             break;
2374
2375           case MO_USE:
2376           case MO_SET:
2377             {
2378               rtx loc = VTI (bb)->mos[i].u.loc;
2379
2380               if (REG_P (loc))
2381                 var_reg_delete_and_set (&set, loc);
2382               else
2383                 var_mem_delete_and_set (&set, loc);
2384
2385               if (VTI (bb)->mos[i].type == MO_USE)
2386                 emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2387               else
2388                 emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2389             }
2390             break;
2391
2392           case MO_USE_NO_VAR:
2393           case MO_CLOBBER:
2394             {
2395               rtx loc = VTI (bb)->mos[i].u.loc;
2396
2397               if (REG_P (loc))
2398                 var_reg_delete (&set, loc);
2399               else
2400                 var_mem_delete (&set, loc);
2401
2402               if (VTI (bb)->mos[i].type == MO_USE_NO_VAR)
2403                 emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2404               else
2405                 emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2406             }
2407             break;
2408
2409           case MO_ADJUST:
2410             {
2411               rtx base;
2412
2413               set.stack_adjust += VTI (bb)->mos[i].u.adjust;
2414               base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
2415                                                         set.stack_adjust));
2416               set_frame_base_location (&set, base);
2417               emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2418             }
2419             break;
2420         }
2421     }
2422   dataflow_set_destroy (&set);
2423 }
2424
2425 /* Emit notes for the whole function.  */
2426
2427 static void
2428 vt_emit_notes (void)
2429 {
2430   basic_block bb;
2431   dataflow_set *last_out;
2432   dataflow_set empty;
2433
2434 #ifdef ENABLE_CHECKING
2435   if (htab_elements (changed_variables))
2436     abort ();
2437 #endif
2438
2439   /* Enable emitting notes by functions (mainly by set_variable_part and
2440      delete_variable_part).  */
2441   emit_notes = true;
2442
2443   dataflow_set_init (&empty, 7);
2444   last_out = &empty;
2445
2446   FOR_EACH_BB (bb)
2447     {
2448       /* Emit the notes for changes of variable locations between two
2449          subsequent basic blocks.  */
2450       emit_notes_for_differences (BB_HEAD (bb), last_out, &VTI (bb)->in);
2451
2452       /* Emit the notes for the changes in the basic block itself.  */
2453       emit_notes_in_bb (bb);
2454
2455       last_out = &VTI (bb)->out;
2456     }
2457   dataflow_set_destroy (&empty);
2458   emit_notes = false;
2459 }
2460
2461 /* If there is a declaration and offset associated with register/memory RTL
2462    assign declaration to *DECLP and offset to *OFFSETP, and return true.  */
2463
2464 static bool
2465 vt_get_decl_and_offset (rtx rtl, tree *declp, HOST_WIDE_INT *offsetp)
2466 {
2467   if (REG_P (rtl))
2468     {
2469       if (REG_ATTRS (rtl))
2470         {
2471           *declp = REG_EXPR (rtl);
2472           *offsetp = REG_OFFSET (rtl);
2473           return true;
2474         }
2475     }
2476   else if (MEM_P (rtl))
2477     {
2478       if (MEM_ATTRS (rtl))
2479         {
2480           *declp = MEM_EXPR (rtl);
2481           *offsetp = MEM_OFFSET (rtl) ? INTVAL (MEM_OFFSET (rtl)) : 0;
2482           return true;
2483         }
2484     }
2485   return false;
2486 }
2487
2488 /* Insert function parameters to IN and OUT sets of ENTRY_BLOCK.  */
2489
2490 static void
2491 vt_add_function_parameters (void)
2492 {
2493   tree parm;
2494
2495   for (parm = DECL_ARGUMENTS (current_function_decl);
2496        parm; parm = TREE_CHAIN (parm))
2497     {
2498       rtx decl_rtl = DECL_RTL_IF_SET (parm);
2499       rtx incoming = DECL_INCOMING_RTL (parm);
2500       tree decl;
2501       HOST_WIDE_INT offset;
2502       dataflow_set *out;
2503
2504       if (TREE_CODE (parm) != PARM_DECL)
2505         continue;
2506
2507       if (!DECL_NAME (parm))
2508         continue;
2509
2510       if (!decl_rtl || !incoming)
2511         continue;
2512
2513       if (GET_MODE (decl_rtl) == BLKmode || GET_MODE (incoming) == BLKmode)
2514         continue;
2515
2516       if (!vt_get_decl_and_offset (incoming, &decl, &offset))
2517         if (!vt_get_decl_and_offset (decl_rtl, &decl, &offset))
2518           continue;
2519
2520       if (!decl)
2521         continue;
2522
2523 #ifdef ENABLE_CHECKING
2524       if (parm != decl)
2525         abort ();
2526 #endif
2527
2528       incoming = eliminate_regs (incoming, 0, NULL_RTX);
2529       out = &VTI (ENTRY_BLOCK_PTR)->out;
2530
2531       if (REG_P (incoming))
2532         {
2533 #ifdef ENABLE_CHECKING
2534           if (REGNO (incoming) >= FIRST_PSEUDO_REGISTER)
2535             abort ();
2536 #endif
2537           attrs_list_insert (&out->regs[REGNO (incoming)],
2538                              parm, offset, incoming);
2539           set_variable_part (out, incoming, parm, offset);
2540         }
2541       else if (MEM_P (incoming))
2542         {
2543           set_variable_part (out, incoming, parm, offset);
2544         }
2545     }
2546 }
2547
2548 /* Allocate and initialize the data structures for variable tracking
2549    and parse the RTL to get the micro operations.  */
2550
2551 static void
2552 vt_initialize (void)
2553 {
2554   basic_block bb;
2555
2556   alloc_aux_for_blocks (sizeof (struct variable_tracking_info_def));
2557
2558   FOR_EACH_BB (bb)
2559     {
2560       rtx insn;
2561       HOST_WIDE_INT pre, post;
2562
2563       /* Count the number of micro operations.  */
2564       VTI (bb)->n_mos = 0;
2565       for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
2566            insn = NEXT_INSN (insn))
2567         {
2568           if (INSN_P (insn))
2569             {
2570               if (!frame_pointer_needed)
2571                 {
2572                   insn_stack_adjust_offset_pre_post (insn, &pre, &post);
2573                   if (pre)
2574                     VTI (bb)->n_mos++;
2575                   if (post)
2576                     VTI (bb)->n_mos++;
2577                 }
2578               note_uses (&PATTERN (insn), count_uses_1, insn);
2579               note_stores (PATTERN (insn), count_stores, insn);
2580               if (CALL_P (insn))
2581                 VTI (bb)->n_mos++;
2582             }
2583         }
2584
2585       /* Add the micro-operations to the array.  */
2586       VTI (bb)->mos = xmalloc (VTI (bb)->n_mos
2587                                * sizeof (struct micro_operation_def));
2588       VTI (bb)->n_mos = 0;
2589       for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
2590            insn = NEXT_INSN (insn))
2591         {
2592           if (INSN_P (insn))
2593             {
2594               int n1, n2;
2595
2596               if (!frame_pointer_needed)
2597                 {
2598                   insn_stack_adjust_offset_pre_post (insn, &pre, &post);
2599                   if (pre)
2600                     {
2601                       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2602
2603                       mo->type = MO_ADJUST;
2604                       mo->u.adjust = pre;
2605                       mo->insn = insn;
2606                     }
2607                 }
2608
2609               n1 = VTI (bb)->n_mos;
2610               note_uses (&PATTERN (insn), add_uses_1, insn);
2611               n2 = VTI (bb)->n_mos - 1;
2612
2613               /* Order the MO_USEs to be before MO_USE_NO_VARs.  */
2614               while (n1 < n2)
2615                 {
2616                   while (n1 < n2 && VTI (bb)->mos[n1].type == MO_USE)
2617                     n1++;
2618                   while (n1 < n2 && VTI (bb)->mos[n2].type == MO_USE_NO_VAR)
2619                     n2--;
2620                   if (n1 < n2)
2621                     {
2622                       micro_operation sw;
2623
2624                       sw = VTI (bb)->mos[n1];
2625                       VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
2626                       VTI (bb)->mos[n2] = sw;
2627                     }
2628                 }
2629
2630               if (CALL_P (insn))
2631                 {
2632                   micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2633
2634                   mo->type = MO_CALL;
2635                   mo->insn = insn;
2636                 }
2637
2638               n1 = VTI (bb)->n_mos;
2639               note_stores (PATTERN (insn), add_stores, insn);
2640               n2 = VTI (bb)->n_mos - 1;
2641
2642               /* Order the MO_SETs to be before MO_CLOBBERs.  */
2643               while (n1 < n2)
2644                 {
2645                   while (n1 < n2 && VTI (bb)->mos[n1].type == MO_SET)
2646                     n1++;
2647                   while (n1 < n2 && VTI (bb)->mos[n2].type == MO_CLOBBER)
2648                     n2--;
2649                   if (n1 < n2)
2650                     {
2651                       micro_operation sw;
2652
2653                       sw = VTI (bb)->mos[n1];
2654                       VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
2655                       VTI (bb)->mos[n2] = sw;
2656                     }
2657                 }
2658
2659               if (!frame_pointer_needed && post)
2660                 {
2661                   micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2662
2663                   mo->type = MO_ADJUST;
2664                   mo->u.adjust = post;
2665                   mo->insn = insn;
2666                 }
2667             }
2668         }
2669     }
2670
2671   /* Init the IN and OUT sets.  */
2672   FOR_ALL_BB (bb)
2673     {
2674       VTI (bb)->visited = false;
2675       dataflow_set_init (&VTI (bb)->in, 7);
2676       dataflow_set_init (&VTI (bb)->out, 7);
2677     }
2678
2679   attrs_pool = create_alloc_pool ("attrs_def pool",
2680                                   sizeof (struct attrs_def), 1024);
2681   var_pool = create_alloc_pool ("variable_def pool",
2682                                 sizeof (struct variable_def), 64);
2683   loc_chain_pool = create_alloc_pool ("location_chain_def pool",
2684                                       sizeof (struct location_chain_def),
2685                                       1024);
2686   changed_variables = htab_create (10, variable_htab_hash, variable_htab_eq,
2687                                    NULL);
2688   vt_add_function_parameters ();
2689
2690   if (!frame_pointer_needed)
2691     {
2692       rtx base;
2693
2694       /* Create fake variable for tracking stack pointer changes.  */
2695       frame_base_decl = make_node (VAR_DECL);
2696       DECL_NAME (frame_base_decl) = get_identifier ("___frame_base_decl");
2697       TREE_TYPE (frame_base_decl) = char_type_node;
2698       DECL_ARTIFICIAL (frame_base_decl) = 1;
2699
2700       /* Set its initial "location".  */
2701       frame_stack_adjust = -prologue_stack_adjust ();
2702       base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
2703                                                 frame_stack_adjust));
2704       set_variable_part (&VTI (ENTRY_BLOCK_PTR)->out, base, frame_base_decl, 0);
2705     }
2706   else
2707     {
2708       frame_base_decl = NULL;
2709     }
2710 }
2711
2712 /* Free the data structures needed for variable tracking.  */
2713
2714 static void
2715 vt_finalize (void)
2716 {
2717   basic_block bb;
2718
2719   FOR_EACH_BB (bb)
2720     {
2721       free (VTI (bb)->mos);
2722     }
2723
2724   FOR_ALL_BB (bb)
2725     {
2726       dataflow_set_destroy (&VTI (bb)->in);
2727       dataflow_set_destroy (&VTI (bb)->out);
2728     }
2729   free_aux_for_blocks ();
2730   free_alloc_pool (attrs_pool);
2731   free_alloc_pool (var_pool);
2732   free_alloc_pool (loc_chain_pool);
2733   htab_delete (changed_variables);
2734 }
2735
2736 /* The entry point to variable tracking pass.  */
2737
2738 void
2739 variable_tracking_main (void)
2740 {
2741   if (n_basic_blocks > 500 && n_edges / n_basic_blocks >= 20)
2742     return;
2743
2744   mark_dfs_back_edges ();
2745   vt_initialize ();
2746   if (!frame_pointer_needed)
2747     {
2748       if (!vt_stack_adjustments ())
2749         {
2750           vt_finalize ();
2751           return;
2752         }
2753     }
2754
2755   vt_find_locations ();
2756   vt_emit_notes ();
2757
2758   if (dump_file)
2759     {
2760       dump_dataflow_sets ();
2761       dump_flow_info (dump_file);
2762     }
2763
2764   vt_finalize ();
2765 }