gcc/var-tracking.c

   1 /* Variable tracking routines for the GNU compiler.
   2    Copyright (C) 2002, 2003, 2004, 2005 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) (DECL_UID (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               gcc_assert (GET_CODE (XEXP (src, 1)) == PLUS &&
 391                           GET_CODE (val) == CONST_INT);
 392
 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   gcc_assert (var->refcount > 0);
 643
 644   var->refcount--;
 645   if (var->refcount > 0)
 646     return;
 647
 648   for (i = 0; i < var->n_var_parts; i++)
 649     {
 650       for (node = var->var_part[i].loc_chain; node; node = next)
 651         {
 652           next = node->next;
 653           pool_free (loc_chain_pool, node);
 654         }
 655       var->var_part[i].loc_chain = NULL;
 656     }
 657   pool_free (var_pool, var);
 658 }
 659
 660 /* Initialize the set (array) SET of attrs to empty lists.  */
 661
 662 static void
 663 init_attrs_list_set (attrs *set)
 664 {
 665   int i;
 666
 667   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 668     set[i] = NULL;
 669 }
 670
 671 /* Make the list *LISTP empty.  */
 672
 673 static void
 674 attrs_list_clear (attrs *listp)
 675 {
 676   attrs list, next;
 677
 678   for (list = *listp; list; list = next)
 679     {
 680       next = list->next;
 681       pool_free (attrs_pool, list);
 682     }
 683   *listp = NULL;
 684 }
 685
 686 /* Return true if the pair of DECL and OFFSET is the member of the LIST.  */
 687
 688 static attrs
 689 attrs_list_member (attrs list, tree decl, HOST_WIDE_INT offset)
 690 {
 691   for (; list; list = list->next)
 692     if (list->decl == decl && list->offset == offset)
 693       return list;
 694   return NULL;
 695 }
 696
 697 /* Insert the triplet DECL, OFFSET, LOC to the list *LISTP.  */
 698
 699 static void
 700 attrs_list_insert (attrs *listp, tree decl, HOST_WIDE_INT offset, rtx loc)
 701 {
 702   attrs list;
 703
 704   list = pool_alloc (attrs_pool);
 705   list->loc = loc;
 706   list->decl = decl;
 707   list->offset = offset;
 708   list->next = *listp;
 709   *listp = list;
 710 }
 711
 712 /* Copy all nodes from SRC and create a list *DSTP of the copies.  */
 713
 714 static void
 715 attrs_list_copy (attrs *dstp, attrs src)
 716 {
 717   attrs n;
 718
 719   attrs_list_clear (dstp);
 720   for (; src; src = src->next)
 721     {
 722       n = pool_alloc (attrs_pool);
 723       n->loc = src->loc;
 724       n->decl = src->decl;
 725       n->offset = src->offset;
 726       n->next = *dstp;
 727       *dstp = n;
 728     }
 729 }
 730
 731 /* Add all nodes from SRC which are not in *DSTP to *DSTP.  */
 732
 733 static void
 734 attrs_list_union (attrs *dstp, attrs src)
 735 {
 736   for (; src; src = src->next)
 737     {
 738       if (!attrs_list_member (*dstp, src->decl, src->offset))
 739         attrs_list_insert (dstp, src->decl, src->offset, src->loc);
 740     }
 741 }
 742
 743 /* Delete all variables from hash table VARS.  */
 744
 745 static void
 746 vars_clear (htab_t vars)
 747 {
 748   htab_empty (vars);
 749 }
 750
 751 /* Return a copy of a variable VAR and insert it to dataflow set SET.  */
 752
 753 static variable
 754 unshare_variable (dataflow_set *set, variable var)
 755 {
 756   void **slot;
 757   variable new_var;
 758   int i;
 759
 760   new_var = pool_alloc (var_pool);
 761   new_var->decl = var->decl;
 762   new_var->refcount = 1;
 763   var->refcount--;
 764   new_var->n_var_parts = var->n_var_parts;
 765
 766   for (i = 0; i < var->n_var_parts; i++)
 767     {
 768       location_chain node;
 769       location_chain *nextp;
 770
 771       new_var->var_part[i].offset = var->var_part[i].offset;
 772       nextp = &new_var->var_part[i].loc_chain;
 773       for (node = var->var_part[i].loc_chain; node; node = node->next)
 774         {
 775           location_chain new_lc;
 776
 777           new_lc = pool_alloc (loc_chain_pool);
 778           new_lc->next = NULL;
 779           new_lc->loc = node->loc;
 780
 781           *nextp = new_lc;
 782           nextp = &new_lc->next;
 783         }
 784
 785       /* We are at the basic block boundary when copying variable description
 786          so set the CUR_LOC to be the first element of the chain.  */
 787       if (new_var->var_part[i].loc_chain)
 788         new_var->var_part[i].cur_loc = new_var->var_part[i].loc_chain->loc;
 789       else
 790         new_var->var_part[i].cur_loc = NULL;
 791     }
 792
 793   slot = htab_find_slot_with_hash (set->vars, new_var->decl,
 794                                    VARIABLE_HASH_VAL (new_var->decl),
 795                                    INSERT);
 796   *slot = new_var;
 797   return new_var;
 798 }
 799
 800 /* Add a variable from *SLOT to hash table DATA and increase its reference
 801    count.  */
 802
 803 static int
 804 vars_copy_1 (void **slot, void *data)
 805 {
 806   htab_t dst = (htab_t) data;
 807   variable src, *dstp;
 808
 809   src = *(variable *) slot;
 810   src->refcount++;
 811
 812   dstp = (variable *) htab_find_slot_with_hash (dst, src->decl,
 813                                                 VARIABLE_HASH_VAL (src->decl),
 814                                                 INSERT);
 815   *dstp = src;
 816
 817   /* Continue traversing the hash table.  */
 818   return 1;
 819 }
 820
 821 /* Copy all variables from hash table SRC to hash table DST.  */
 822
 823 static void
 824 vars_copy (htab_t dst, htab_t src)
 825 {
 826   vars_clear (dst);
 827   htab_traverse (src, vars_copy_1, dst);
 828 }
 829
 830 /* Delete current content of register LOC in dataflow set SET
 831    and set the register to contain REG_EXPR (LOC), REG_OFFSET (LOC).  */
 832
 833 static void
 834 var_reg_delete_and_set (dataflow_set *set, rtx loc)
 835 {
 836   tree decl = REG_EXPR (loc);
 837   HOST_WIDE_INT offset = REG_OFFSET (loc);
 838   attrs node, next;
 839   attrs *nextp;
 840
 841   nextp = &set->regs[REGNO (loc)];
 842   for (node = *nextp; node; node = next)
 843     {
 844       next = node->next;
 845       if (node->decl != decl || node->offset != offset)
 846         {
 847           delete_variable_part (set, node->loc, node->decl, node->offset);
 848           pool_free (attrs_pool, node);
 849           *nextp = next;
 850         }
 851       else
 852         {
 853           node->loc = loc;
 854           nextp = &node->next;
 855         }
 856     }
 857   if (set->regs[REGNO (loc)] == NULL)
 858     attrs_list_insert (&set->regs[REGNO (loc)], decl, offset, loc);
 859   set_variable_part (set, loc, decl, offset);
 860 }
 861
 862 /* Delete current content of register LOC in dataflow set SET.  */
 863
 864 static void
 865 var_reg_delete (dataflow_set *set, rtx loc)
 866 {
 867   attrs *reg = &set->regs[REGNO (loc)];
 868   attrs node, next;
 869
 870   for (node = *reg; node; node = next)
 871     {
 872       next = node->next;
 873       delete_variable_part (set, node->loc, node->decl, node->offset);
 874       pool_free (attrs_pool, node);
 875     }
 876   *reg = NULL;
 877 }
 878
 879 /* Delete content of register with number REGNO in dataflow set SET.  */
 880
 881 static void
 882 var_regno_delete (dataflow_set *set, int regno)
 883 {
 884   attrs *reg = &set->regs[regno];
 885   attrs node, next;
 886
 887   for (node = *reg; node; node = next)
 888     {
 889       next = node->next;
 890       delete_variable_part (set, node->loc, node->decl, node->offset);
 891       pool_free (attrs_pool, node);
 892     }
 893   *reg = NULL;
 894 }
 895
 896 /* Delete and set the location part of variable MEM_EXPR (LOC)
 897    in dataflow set SET to LOC.
 898    Adjust the address first if it is stack pointer based.  */
 899
 900 static void
 901 var_mem_delete_and_set (dataflow_set *set, rtx loc)
 902 {
 903   tree decl = MEM_EXPR (loc);
 904   HOST_WIDE_INT offset = MEM_OFFSET (loc) ? INTVAL (MEM_OFFSET (loc)) : 0;
 905
 906   set_variable_part (set, loc, decl, offset);
 907 }
 908
 909 /* Delete the location part LOC from dataflow set SET.
 910    Adjust the address first if it is stack pointer based.  */
 911
 912 static void
 913 var_mem_delete (dataflow_set *set, rtx loc)
 914 {
 915   tree decl = MEM_EXPR (loc);
 916   HOST_WIDE_INT offset = MEM_OFFSET (loc) ? INTVAL (MEM_OFFSET (loc)) : 0;
 917
 918   delete_variable_part (set, loc, decl, offset);
 919 }
 920
 921 /* Initialize dataflow set SET to be empty.
 922    VARS_SIZE is the initial size of hash table VARS.  */
 923
 924 static void
 925 dataflow_set_init (dataflow_set *set, int vars_size)
 926 {
 927   init_attrs_list_set (set->regs);
 928   set->vars = htab_create (vars_size, variable_htab_hash, variable_htab_eq,
 929                            variable_htab_free);
 930   set->stack_adjust = 0;
 931 }
 932
 933 /* Delete the contents of dataflow set SET.  */
 934
 935 static void
 936 dataflow_set_clear (dataflow_set *set)
 937 {
 938   int i;
 939
 940   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 941     attrs_list_clear (&set->regs[i]);
 942
 943   vars_clear (set->vars);
 944 }
 945
 946 /* Copy the contents of dataflow set SRC to DST.  */
 947
 948 static void
 949 dataflow_set_copy (dataflow_set *dst, dataflow_set *src)
 950 {
 951   int i;
 952
 953   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 954     attrs_list_copy (&dst->regs[i], src->regs[i]);
 955
 956   vars_copy (dst->vars, src->vars);
 957   dst->stack_adjust = src->stack_adjust;
 958 }
 959
 960 /* Information for merging lists of locations for a given offset of variable.
 961  */
 962 struct variable_union_info
 963 {
 964   /* Node of the location chain.  */
 965   location_chain lc;
 966
 967   /* The sum of positions in the input chains.  */
 968   int pos;
 969
 970   /* The position in the chains of SRC and DST dataflow sets.  */
 971   int pos_src;
 972   int pos_dst;
 973 };
 974
 975 /* Compare function for qsort, order the structures by POS element.  */
 976
 977 static int
 978 variable_union_info_cmp_pos (const void *n1, const void *n2)
 979 {
 980   const struct variable_union_info *i1 = n1;
 981   const struct variable_union_info *i2 = n2;
 982
 983   if (i1->pos != i2->pos)
 984     return i1->pos - i2->pos;
 985
 986   return (i1->pos_dst - i2->pos_dst);
 987 }
 988
 989 /* Compute union of location parts of variable *SLOT and the same variable
 990    from hash table DATA.  Compute "sorted" union of the location chains
 991    for common offsets, i.e. the locations of a variable part are sorted by
 992    a priority where the priority is the sum of the positions in the 2 chains
 993    (if a location is only in one list the position in the second list is
 994    defined to be larger than the length of the chains).
 995    When we are updating the location parts the newest location is in the
 996    beginning of the chain, so when we do the described "sorted" union
 997    we keep the newest locations in the beginning.  */
 998
 999 static int
1000 variable_union (void **slot, void *data)
1001 {
1002   variable src, dst, *dstp;
1003   dataflow_set *set = (dataflow_set *) data;
1004   int i, j, k;
1005
1006   src = *(variable *) slot;
1007   dstp = (variable *) htab_find_slot_with_hash (set->vars, src->decl,
1008                                                 VARIABLE_HASH_VAL (src->decl),
1009                                                 INSERT);
1010   if (!*dstp)
1011     {
1012       src->refcount++;
1013
1014       /* If CUR_LOC of some variable part is not the first element of
1015          the location chain we are going to change it so we have to make
1016          a copy of the variable.  */
1017       for (k = 0; k < src->n_var_parts; k++)
1018         {
1019           gcc_assert (!src->var_part[k].loc_chain
1020                       == !src->var_part[k].cur_loc);
1021           if (src->var_part[k].loc_chain)
1022             {
1023               gcc_assert (src->var_part[k].cur_loc);
1024               if (src->var_part[k].cur_loc != src->var_part[k].loc_chain->loc)
1025                 break;
1026             }
1027         }
1028       if (k < src->n_var_parts)
1029         unshare_variable (set, src);
1030       else
1031         *dstp = src;
1032
1033       /* Continue traversing the hash table.  */
1034       return 1;
1035     }
1036   else
1037     dst = *dstp;
1038
1039   gcc_assert (src->n_var_parts);
1040
1041   /* Count the number of location parts, result is K.  */
1042   for (i = 0, j = 0, k = 0;
1043        i < src->n_var_parts && j < dst->n_var_parts; k++)
1044     {
1045       if (src->var_part[i].offset == dst->var_part[j].offset)
1046         {
1047           i++;
1048           j++;
1049         }
1050       else if (src->var_part[i].offset < dst->var_part[j].offset)
1051         i++;
1052       else
1053         j++;
1054     }
1055   k += src->n_var_parts - i;
1056   k += dst->n_var_parts - j;
1057
1058   /* We track only variables whose size is <= MAX_VAR_PARTS bytes
1059      thus there are at most MAX_VAR_PARTS different offsets.  */
1060   gcc_assert (k <= MAX_VAR_PARTS);
1061
1062   if (dst->refcount > 1 && dst->n_var_parts != k)
1063     dst = unshare_variable (set, dst);
1064
1065   i = src->n_var_parts - 1;
1066   j = dst->n_var_parts - 1;
1067   dst->n_var_parts = k;
1068
1069   for (k--; k >= 0; k--)
1070     {
1071       location_chain node, node2;
1072
1073       if (i >= 0 && j >= 0
1074           && src->var_part[i].offset == dst->var_part[j].offset)
1075         {
1076           /* Compute the "sorted" union of the chains, i.e. the locations which
1077              are in both chains go first, they are sorted by the sum of
1078              positions in the chains.  */
1079           int dst_l, src_l;
1080           int ii, jj, n;
1081           struct variable_union_info *vui;
1082
1083           /* If DST is shared compare the location chains.
1084              If they are different we will modify the chain in DST with
1085              high probability so make a copy of DST.  */
1086           if (dst->refcount > 1)
1087             {
1088               for (node = src->var_part[i].loc_chain,
1089                    node2 = dst->var_part[j].loc_chain; node && node2;
1090                    node = node->next, node2 = node2->next)
1091                 {
1092                   if (!((REG_P (node2->loc)
1093                          && REG_P (node->loc)
1094                          && REGNO (node2->loc) == REGNO (node->loc))
1095                         || rtx_equal_p (node2->loc, node->loc)))
1096                     break;
1097                 }
1098               if (node || node2)
1099                 dst = unshare_variable (set, dst);
1100             }
1101
1102           src_l = 0;
1103           for (node = src->var_part[i].loc_chain; node; node = node->next)
1104             src_l++;
1105           dst_l = 0;
1106           for (node = dst->var_part[j].loc_chain; node; node = node->next)
1107             dst_l++;
1108           vui = xcalloc (src_l + dst_l, sizeof (struct variable_union_info));
1109
1110           /* Fill in the locations from DST.  */
1111           for (node = dst->var_part[j].loc_chain, jj = 0; node;
1112                node = node->next, jj++)
1113             {
1114               vui[jj].lc = node;
1115               vui[jj].pos_dst = jj;
1116
1117               /* Value larger than a sum of 2 valid positions.  */
1118               vui[jj].pos_src = src_l + dst_l;
1119             }
1120
1121           /* Fill in the locations from SRC.  */
1122           n = dst_l;
1123           for (node = src->var_part[i].loc_chain, ii = 0; node;
1124                node = node->next, ii++)
1125             {
1126               /* Find location from NODE.  */
1127               for (jj = 0; jj < dst_l; jj++)
1128                 {
1129                   if ((REG_P (vui[jj].lc->loc)
1130                        && REG_P (node->loc)
1131                        && REGNO (vui[jj].lc->loc) == REGNO (node->loc))
1132                       || rtx_equal_p (vui[jj].lc->loc, node->loc))
1133                     {
1134                       vui[jj].pos_src = ii;
1135                       break;
1136                     }
1137                 }
1138               if (jj >= dst_l)  /* The location has not been found.  */
1139                 {
1140                   location_chain new_node;
1141
1142                   /* Copy the location from SRC.  */
1143                   new_node = pool_alloc (loc_chain_pool);
1144                   new_node->loc = node->loc;
1145                   vui[n].lc = new_node;
1146                   vui[n].pos_src = ii;
1147                   vui[n].pos_dst = src_l + dst_l;
1148                   n++;
1149                 }
1150             }
1151
1152           for (ii = 0; ii < src_l + dst_l; ii++)
1153             vui[ii].pos = vui[ii].pos_src + vui[ii].pos_dst;
1154
1155           qsort (vui, n, sizeof (struct variable_union_info),
1156                  variable_union_info_cmp_pos);
1157
1158           /* Reconnect the nodes in sorted order.  */
1159           for (ii = 1; ii < n; ii++)
1160             vui[ii - 1].lc->next = vui[ii].lc;
1161           vui[n - 1].lc->next = NULL;
1162
1163           dst->var_part[k].loc_chain = vui[0].lc;
1164           dst->var_part[k].offset = dst->var_part[j].offset;
1165
1166           free (vui);
1167           i--;
1168           j--;
1169         }
1170       else if ((i >= 0 && j >= 0
1171                 && src->var_part[i].offset < dst->var_part[j].offset)
1172                || i < 0)
1173         {
1174           dst->var_part[k] = dst->var_part[j];
1175           j--;
1176         }
1177       else if ((i >= 0 && j >= 0
1178                 && src->var_part[i].offset > dst->var_part[j].offset)
1179                || j < 0)
1180         {
1181           location_chain *nextp;
1182
1183           /* Copy the chain from SRC.  */
1184           nextp = &dst->var_part[k].loc_chain;
1185           for (node = src->var_part[i].loc_chain; node; node = node->next)
1186             {
1187               location_chain new_lc;
1188
1189               new_lc = pool_alloc (loc_chain_pool);
1190               new_lc->next = NULL;
1191               new_lc->loc = node->loc;
1192
1193               *nextp = new_lc;
1194               nextp = &new_lc->next;
1195             }
1196
1197           dst->var_part[k].offset = src->var_part[i].offset;
1198           i--;
1199         }
1200
1201       /* We are at the basic block boundary when computing union
1202          so set the CUR_LOC to be the first element of the chain.  */
1203       if (dst->var_part[k].loc_chain)
1204         dst->var_part[k].cur_loc = dst->var_part[k].loc_chain->loc;
1205       else
1206         dst->var_part[k].cur_loc = NULL;
1207     }
1208
1209   /* Continue traversing the hash table.  */
1210   return 1;
1211 }
1212
1213 /* Compute union of dataflow sets SRC and DST and store it to DST.  */
1214
1215 static void
1216 dataflow_set_union (dataflow_set *dst, dataflow_set *src)
1217 {
1218   int i;
1219
1220   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1221     attrs_list_union (&dst->regs[i], src->regs[i]);
1222
1223   htab_traverse (src->vars, variable_union, dst);
1224 }
1225
1226 /* Flag whether two dataflow sets being compared contain different data.  */
1227 static bool
1228 dataflow_set_different_value;
1229
1230 static bool
1231 variable_part_different_p (variable_part *vp1, variable_part *vp2)
1232 {
1233   location_chain lc1, lc2;
1234
1235   for (lc1 = vp1->loc_chain; lc1; lc1 = lc1->next)
1236     {
1237       for (lc2 = vp2->loc_chain; lc2; lc2 = lc2->next)
1238         {
1239           if (REG_P (lc1->loc) && REG_P (lc2->loc))
1240             {
1241               if (REGNO (lc1->loc) == REGNO (lc2->loc))
1242                 break;
1243             }
1244           if (rtx_equal_p (lc1->loc, lc2->loc))
1245             break;
1246         }
1247       if (!lc2)
1248         return true;
1249     }
1250   return false;
1251 }
1252
1253 /* Return true if variables VAR1 and VAR2 are different.
1254    If COMPARE_CURRENT_LOCATION is true compare also the cur_loc of each
1255    variable part.  */
1256
1257 static bool
1258 variable_different_p (variable var1, variable var2,
1259                       bool compare_current_location)
1260 {
1261   int i;
1262
1263   if (var1 == var2)
1264     return false;
1265
1266   if (var1->n_var_parts != var2->n_var_parts)
1267     return true;
1268
1269   for (i = 0; i < var1->n_var_parts; i++)
1270     {
1271       if (var1->var_part[i].offset != var2->var_part[i].offset)
1272         return true;
1273       if (compare_current_location)
1274         {
1275           if (!((REG_P (var1->var_part[i].cur_loc)
1276                  && REG_P (var2->var_part[i].cur_loc)
1277                  && (REGNO (var1->var_part[i].cur_loc)
1278                      == REGNO (var2->var_part[i].cur_loc)))
1279                 || rtx_equal_p (var1->var_part[i].cur_loc,
1280                                 var2->var_part[i].cur_loc)))
1281             return true;
1282         }
1283       if (variable_part_different_p (&var1->var_part[i], &var2->var_part[i]))
1284         return true;
1285       if (variable_part_different_p (&var2->var_part[i], &var1->var_part[i]))
1286         return true;
1287     }
1288   return false;
1289 }
1290
1291 /* Compare variable *SLOT with the same variable in hash table DATA
1292    and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */
1293
1294 static int
1295 dataflow_set_different_1 (void **slot, void *data)
1296 {
1297   htab_t htab = (htab_t) data;
1298   variable var1, var2;
1299
1300   var1 = *(variable *) slot;
1301   var2 = htab_find_with_hash (htab, var1->decl,
1302                               VARIABLE_HASH_VAL (var1->decl));
1303   if (!var2)
1304     {
1305       dataflow_set_different_value = true;
1306
1307       /* Stop traversing the hash table.  */
1308       return 0;
1309     }
1310
1311   if (variable_different_p (var1, var2, false))
1312     {
1313       dataflow_set_different_value = true;
1314
1315       /* Stop traversing the hash table.  */
1316       return 0;
1317     }
1318
1319   /* Continue traversing the hash table.  */
1320   return 1;
1321 }
1322
1323 /* Compare variable *SLOT with the same variable in hash table DATA
1324    and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */
1325
1326 static int
1327 dataflow_set_different_2 (void **slot, void *data)
1328 {
1329   htab_t htab = (htab_t) data;
1330   variable var1, var2;
1331
1332   var1 = *(variable *) slot;
1333   var2 = htab_find_with_hash (htab, var1->decl,
1334                               VARIABLE_HASH_VAL (var1->decl));
1335   if (!var2)
1336     {
1337       dataflow_set_different_value = true;
1338
1339       /* Stop traversing the hash table.  */
1340       return 0;
1341     }
1342
1343   /* If both variables are defined they have been already checked for
1344      equivalence.  */
1345   gcc_assert (!variable_different_p (var1, var2, false));
1346
1347   /* Continue traversing the hash table.  */
1348   return 1;
1349 }
1350
1351 /* Return true if dataflow sets OLD_SET and NEW_SET differ.  */
1352
1353 static bool
1354 dataflow_set_different (dataflow_set *old_set, dataflow_set *new_set)
1355 {
1356   dataflow_set_different_value = false;
1357
1358   htab_traverse (old_set->vars, dataflow_set_different_1, new_set->vars);
1359   if (!dataflow_set_different_value)
1360     {
1361       /* We have compared the variables which are in both hash tables
1362          so now only check whether there are some variables in NEW_SET->VARS
1363          which are not in OLD_SET->VARS.  */
1364       htab_traverse (new_set->vars, dataflow_set_different_2, old_set->vars);
1365     }
1366   return dataflow_set_different_value;
1367 }
1368
1369 /* Free the contents of dataflow set SET.  */
1370
1371 static void
1372 dataflow_set_destroy (dataflow_set *set)
1373 {
1374   int i;
1375
1376   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1377     attrs_list_clear (&set->regs[i]);
1378
1379   htab_delete (set->vars);
1380   set->vars = NULL;
1381 }
1382
1383 /* Return true if RTL X contains a SYMBOL_REF.  */
1384
1385 static bool
1386 contains_symbol_ref (rtx x)
1387 {
1388   const char *fmt;
1389   RTX_CODE code;
1390   int i;
1391
1392   if (!x)
1393     return false;
1394
1395   code = GET_CODE (x);
1396   if (code == SYMBOL_REF)
1397     return true;
1398
1399   fmt = GET_RTX_FORMAT (code);
1400   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1401     {
1402       if (fmt[i] == 'e')
1403         {
1404           if (contains_symbol_ref (XEXP (x, i)))
1405             return true;
1406         }
1407       else if (fmt[i] == 'E')
1408         {
1409           int j;
1410           for (j = 0; j < XVECLEN (x, i); j++)
1411             if (contains_symbol_ref (XVECEXP (x, i, j)))
1412               return true;
1413         }
1414     }
1415
1416   return false;
1417 }
1418
1419 /* Shall EXPR be tracked?  */
1420
1421 static bool
1422 track_expr_p (tree expr)
1423 {
1424   rtx decl_rtl;
1425   tree realdecl;
1426
1427   /* If EXPR is not a parameter or a variable do not track it.  */
1428   if (TREE_CODE (expr) != VAR_DECL && TREE_CODE (expr) != PARM_DECL)
1429     return 0;
1430
1431   /* It also must have a name...  */
1432   if (!DECL_NAME (expr))
1433     return 0;
1434
1435   /* ... and a RTL assigned to it.  */
1436   decl_rtl = DECL_RTL_IF_SET (expr);
1437   if (!decl_rtl)
1438     return 0;
1439
1440   /* If this expression is really a debug alias of some other declaration, we
1441      don't need to track this expression if the ultimate declaration is
1442      ignored.  */
1443   realdecl = expr;
1444   if (DECL_DEBUG_EXPR_IS_FROM (realdecl) && DECL_DEBUG_EXPR (realdecl))
1445     {
1446       realdecl = DECL_DEBUG_EXPR (realdecl);
1447       /* ??? We don't yet know how to emit DW_OP_piece for variable
1448          that has been SRA'ed.  */
1449       if (!DECL_P (realdecl))
1450         return 0;
1451     }
1452
1453   /* Do not track EXPR if REALDECL it should be ignored for debugging
1454      purposes.  */
1455   if (DECL_IGNORED_P (realdecl))
1456     return 0;
1457
1458   /* Do not track global variables until we are able to emit correct location
1459      list for them.  */
1460   if (TREE_STATIC (realdecl))
1461     return 0;
1462
1463   /* When the EXPR is a DECL for alias of some variable (see example)
1464      the TREE_STATIC flag is not used.  Disable tracking all DECLs whose
1465      DECL_RTL contains SYMBOL_REF.
1466
1467      Example:
1468      extern char **_dl_argv_internal __attribute__ ((alias ("_dl_argv")));
1469      char **_dl_argv;
1470   */
1471   if (MEM_P (decl_rtl)
1472       && contains_symbol_ref (XEXP (decl_rtl, 0)))
1473     return 0;
1474
1475   /* If RTX is a memory it should not be very large (because it would be
1476      an array or struct).  */
1477   if (MEM_P (decl_rtl))
1478     {
1479       /* Do not track structures and arrays.  */
1480       if (GET_MODE (decl_rtl) == BLKmode)
1481         return 0;
1482       if (MEM_SIZE (decl_rtl)
1483           && INTVAL (MEM_SIZE (decl_rtl)) > MAX_VAR_PARTS)
1484         return 0;
1485     }
1486
1487   return 1;
1488 }
1489
1490 /* Count uses (register and memory references) LOC which will be tracked.
1491    INSN is instruction which the LOC is part of.  */
1492
1493 static int
1494 count_uses (rtx *loc, void *insn)
1495 {
1496   basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1497
1498   if (REG_P (*loc))
1499     {
1500       gcc_assert (REGNO (*loc) < FIRST_PSEUDO_REGISTER);
1501       VTI (bb)->n_mos++;
1502     }
1503   else if (MEM_P (*loc)
1504            && MEM_EXPR (*loc)
1505            && track_expr_p (MEM_EXPR (*loc)))
1506     {
1507       VTI (bb)->n_mos++;
1508     }
1509
1510   return 0;
1511 }
1512
1513 /* Helper function for finding all uses of REG/MEM in X in insn INSN.  */
1514
1515 static void
1516 count_uses_1 (rtx *x, void *insn)
1517 {
1518   for_each_rtx (x, count_uses, insn);
1519 }
1520
1521 /* Count stores (register and memory references) LOC which will be tracked.
1522    INSN is instruction which the LOC is part of.  */
1523
1524 static void
1525 count_stores (rtx loc, rtx expr ATTRIBUTE_UNUSED, void *insn)
1526 {
1527   count_uses (&loc, insn);
1528 }
1529
1530 /* Add uses (register and memory references) LOC which will be tracked
1531    to VTI (bb)->mos.  INSN is instruction which the LOC is part of.  */
1532
1533 static int
1534 add_uses (rtx *loc, void *insn)
1535 {
1536   if (REG_P (*loc))
1537     {
1538       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1539       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1540
1541       mo->type = ((REG_EXPR (*loc) && track_expr_p (REG_EXPR (*loc)))
1542                   ? MO_USE : MO_USE_NO_VAR);
1543       mo->u.loc = *loc;
1544       mo->insn = (rtx) insn;
1545     }
1546   else if (MEM_P (*loc)
1547            && MEM_EXPR (*loc)
1548            && track_expr_p (MEM_EXPR (*loc)))
1549     {
1550       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1551       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1552
1553       mo->type = MO_USE;
1554       mo->u.loc = *loc;
1555       mo->insn = (rtx) insn;
1556     }
1557
1558   return 0;
1559 }
1560
1561 /* Helper function for finding all uses of REG/MEM in X in insn INSN.  */
1562
1563 static void
1564 add_uses_1 (rtx *x, void *insn)
1565 {
1566   for_each_rtx (x, add_uses, insn);
1567 }
1568
1569 /* Add stores (register and memory references) LOC which will be tracked
1570    to VTI (bb)->mos. EXPR is the RTL expression containing the store.
1571    INSN is instruction which the LOC is part of.  */
1572
1573 static void
1574 add_stores (rtx loc, rtx expr, void *insn)
1575 {
1576   if (REG_P (loc))
1577     {
1578       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1579       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1580
1581       mo->type = ((GET_CODE (expr) != CLOBBER && REG_EXPR (loc)
1582                    && track_expr_p (REG_EXPR (loc)))
1583                   ? MO_SET : MO_CLOBBER);
1584       mo->u.loc = loc;
1585       mo->insn = (rtx) insn;
1586     }
1587   else if (MEM_P (loc)
1588            && MEM_EXPR (loc)
1589            && track_expr_p (MEM_EXPR (loc)))
1590     {
1591       basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
1592       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
1593
1594       mo->type = GET_CODE (expr) == CLOBBER ? MO_CLOBBER : MO_SET;
1595       mo->u.loc = loc;
1596       mo->insn = (rtx) insn;
1597     }
1598 }
1599
1600 /* Compute the changes of variable locations in the basic block BB.  */
1601
1602 static bool
1603 compute_bb_dataflow (basic_block bb)
1604 {
1605   int i, n, r;
1606   bool changed;
1607   dataflow_set old_out;
1608   dataflow_set *in = &VTI (bb)->in;
1609   dataflow_set *out = &VTI (bb)->out;
1610
1611   dataflow_set_init (&old_out, htab_elements (VTI (bb)->out.vars) + 3);
1612   dataflow_set_copy (&old_out, out);
1613   dataflow_set_copy (out, in);
1614
1615   n = VTI (bb)->n_mos;
1616   for (i = 0; i < n; i++)
1617     {
1618       switch (VTI (bb)->mos[i].type)
1619         {
1620           case MO_CALL:
1621             for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
1622               if (TEST_HARD_REG_BIT (call_used_reg_set, r))
1623                 var_regno_delete (out, r);
1624             break;
1625
1626           case MO_USE:
1627           case MO_SET:
1628             {
1629               rtx loc = VTI (bb)->mos[i].u.loc;
1630
1631               if (REG_P (loc))
1632                 var_reg_delete_and_set (out, loc);
1633               else if (MEM_P (loc))
1634                 var_mem_delete_and_set (out, loc);
1635             }
1636             break;
1637
1638           case MO_USE_NO_VAR:
1639           case MO_CLOBBER:
1640             {
1641               rtx loc = VTI (bb)->mos[i].u.loc;
1642
1643               if (REG_P (loc))
1644                 var_reg_delete (out, loc);
1645               else if (MEM_P (loc))
1646                 var_mem_delete (out, loc);
1647             }
1648             break;
1649
1650           case MO_ADJUST:
1651             {
1652               rtx base;
1653
1654               out->stack_adjust += VTI (bb)->mos[i].u.adjust;
1655               base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
1656                                                         out->stack_adjust));
1657               set_frame_base_location (out, base);
1658             }
1659             break;
1660         }
1661     }
1662
1663   changed = dataflow_set_different (&old_out, out);
1664   dataflow_set_destroy (&old_out);
1665   return changed;
1666 }
1667
1668 /* Find the locations of variables in the whole function.  */
1669
1670 static void
1671 vt_find_locations (void)
1672 {
1673   fibheap_t worklist, pending, fibheap_swap;
1674   sbitmap visited, in_worklist, in_pending, sbitmap_swap;
1675   basic_block bb;
1676   edge e;
1677   int *bb_order;
1678   int *rc_order;
1679   int i;
1680
1681   /* Compute reverse completion order of depth first search of the CFG
1682      so that the data-flow runs faster.  */
1683   rc_order = xmalloc (n_basic_blocks * sizeof (int));
1684   bb_order = xmalloc (last_basic_block * sizeof (int));
1685   flow_depth_first_order_compute (NULL, rc_order);
1686   for (i = 0; i < n_basic_blocks; i++)
1687     bb_order[rc_order[i]] = i;
1688   free (rc_order);
1689
1690   worklist = fibheap_new ();
1691   pending = fibheap_new ();
1692   visited = sbitmap_alloc (last_basic_block);
1693   in_worklist = sbitmap_alloc (last_basic_block);
1694   in_pending = sbitmap_alloc (last_basic_block);
1695   sbitmap_zero (in_worklist);
1696
1697   FOR_EACH_BB (bb)
1698     fibheap_insert (pending, bb_order[bb->index], bb);
1699   sbitmap_ones (in_pending);
1700
1701   while (!fibheap_empty (pending))
1702     {
1703       fibheap_swap = pending;
1704       pending = worklist;
1705       worklist = fibheap_swap;
1706       sbitmap_swap = in_pending;
1707       in_pending = in_worklist;
1708       in_worklist = sbitmap_swap;
1709
1710       sbitmap_zero (visited);
1711
1712       while (!fibheap_empty (worklist))
1713         {
1714           bb = fibheap_extract_min (worklist);
1715           RESET_BIT (in_worklist, bb->index);
1716           if (!TEST_BIT (visited, bb->index))
1717             {
1718               bool changed;
1719               edge_iterator ei;
1720
1721               SET_BIT (visited, bb->index);
1722
1723               /* Calculate the IN set as union of predecessor OUT sets.  */
1724               dataflow_set_clear (&VTI (bb)->in);
1725               FOR_EACH_EDGE (e, ei, bb->preds)
1726                 {
1727                   dataflow_set_union (&VTI (bb)->in, &VTI (e->src)->out);
1728                 }
1729
1730               changed = compute_bb_dataflow (bb);
1731               if (changed)
1732                 {
1733                   FOR_EACH_EDGE (e, ei, bb->succs)
1734                     {
1735                       if (e->dest == EXIT_BLOCK_PTR)
1736                         continue;
1737
1738                       if (e->dest == bb)
1739                         continue;
1740
1741                       if (TEST_BIT (visited, e->dest->index))
1742                         {
1743                           if (!TEST_BIT (in_pending, e->dest->index))
1744                             {
1745                               /* Send E->DEST to next round.  */
1746                               SET_BIT (in_pending, e->dest->index);
1747                               fibheap_insert (pending,
1748                                               bb_order[e->dest->index],
1749                                               e->dest);
1750                             }
1751                         }
1752                       else if (!TEST_BIT (in_worklist, e->dest->index))
1753                         {
1754                           /* Add E->DEST to current round.  */
1755                           SET_BIT (in_worklist, e->dest->index);
1756                           fibheap_insert (worklist, bb_order[e->dest->index],
1757                                           e->dest);
1758                         }
1759                     }
1760                 }
1761             }
1762         }
1763     }
1764
1765   free (bb_order);
1766   fibheap_delete (worklist);
1767   fibheap_delete (pending);
1768   sbitmap_free (visited);
1769   sbitmap_free (in_worklist);
1770   sbitmap_free (in_pending);
1771 }
1772
1773 /* Print the content of the LIST to dump file.  */
1774
1775 static void
1776 dump_attrs_list (attrs list)
1777 {
1778   for (; list; list = list->next)
1779     {
1780       print_mem_expr (dump_file, list->decl);
1781       fprintf (dump_file, "+");
1782       fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, list->offset);
1783     }
1784   fprintf (dump_file, "\n");
1785 }
1786
1787 /* Print the information about variable *SLOT to dump file.  */
1788
1789 static int
1790 dump_variable (void **slot, void *data ATTRIBUTE_UNUSED)
1791 {
1792   variable var = *(variable *) slot;
1793   int i;
1794   location_chain node;
1795
1796   fprintf (dump_file, "  name: %s\n",
1797            IDENTIFIER_POINTER (DECL_NAME (var->decl)));
1798   for (i = 0; i < var->n_var_parts; i++)
1799     {
1800       fprintf (dump_file, "    offset %ld\n",
1801                (long) var->var_part[i].offset);
1802       for (node = var->var_part[i].loc_chain; node; node = node->next)
1803         {
1804           fprintf (dump_file, "      ");
1805           print_rtl_single (dump_file, node->loc);
1806         }
1807     }
1808
1809   /* Continue traversing the hash table.  */
1810   return 1;
1811 }
1812
1813 /* Print the information about variables from hash table VARS to dump file.  */
1814
1815 static void
1816 dump_vars (htab_t vars)
1817 {
1818   if (htab_elements (vars) > 0)
1819     {
1820       fprintf (dump_file, "Variables:\n");
1821       htab_traverse (vars, dump_variable, NULL);
1822     }
1823 }
1824
1825 /* Print the dataflow set SET to dump file.  */
1826
1827 static void
1828 dump_dataflow_set (dataflow_set *set)
1829 {
1830   int i;
1831
1832   fprintf (dump_file, "Stack adjustment: ");
1833   fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, set->stack_adjust);
1834   fprintf (dump_file, "\n");
1835   for (i = 1; i < FIRST_PSEUDO_REGISTER; i++)
1836     {
1837       if (set->regs[i])
1838         {
1839           fprintf (dump_file, "Reg %d:", i);
1840           dump_attrs_list (set->regs[i]);
1841         }
1842     }
1843   dump_vars (set->vars);
1844   fprintf (dump_file, "\n");
1845 }
1846
1847 /* Print the IN and OUT sets for each basic block to dump file.  */
1848
1849 static void
1850 dump_dataflow_sets (void)
1851 {
1852   basic_block bb;
1853
1854   FOR_EACH_BB (bb)
1855     {
1856       fprintf (dump_file, "\nBasic block %d:\n", bb->index);
1857       fprintf (dump_file, "IN:\n");
1858       dump_dataflow_set (&VTI (bb)->in);
1859       fprintf (dump_file, "OUT:\n");
1860       dump_dataflow_set (&VTI (bb)->out);
1861     }
1862 }
1863
1864 /* Add variable VAR to the hash table of changed variables and
1865    if it has no locations delete it from hash table HTAB.  */
1866
1867 static void
1868 variable_was_changed (variable var, htab_t htab)
1869 {
1870   hashval_t hash = VARIABLE_HASH_VAL (var->decl);
1871
1872   if (emit_notes)
1873     {
1874       variable *slot;
1875
1876       slot = (variable *) htab_find_slot_with_hash (changed_variables,
1877                                                     var->decl, hash, INSERT);
1878
1879       if (htab && var->n_var_parts == 0)
1880         {
1881           variable empty_var;
1882           void **old;
1883
1884           empty_var = pool_alloc (var_pool);
1885           empty_var->decl = var->decl;
1886           empty_var->refcount = 1;
1887           empty_var->n_var_parts = 0;
1888           *slot = empty_var;
1889
1890           old = htab_find_slot_with_hash (htab, var->decl, hash,
1891                                           NO_INSERT);
1892           if (old)
1893             htab_clear_slot (htab, old);
1894         }
1895       else
1896         {
1897           *slot = var;
1898         }
1899     }
1900   else
1901     {
1902       gcc_assert (htab);
1903       if (var->n_var_parts == 0)
1904         {
1905           void **slot = htab_find_slot_with_hash (htab, var->decl, hash,
1906                                                   NO_INSERT);
1907           if (slot)
1908             htab_clear_slot (htab, slot);
1909         }
1910     }
1911 }
1912
1913 /* Set the location of frame_base_decl to LOC in dataflow set SET.  This
1914    function expects that frame_base_decl has already one location for offset 0
1915    in the variable table.  */
1916
1917 static void
1918 set_frame_base_location (dataflow_set *set, rtx loc)
1919 {
1920   variable var;
1921
1922   var = htab_find_with_hash (set->vars, frame_base_decl,
1923                              VARIABLE_HASH_VAL (frame_base_decl));
1924   gcc_assert (var);
1925   gcc_assert (var->n_var_parts == 1);
1926   gcc_assert (!var->var_part[0].offset);
1927   gcc_assert (var->var_part[0].loc_chain);
1928
1929   /* If frame_base_decl is shared unshare it first.  */
1930   if (var->refcount > 1)
1931     var = unshare_variable (set, var);
1932
1933   var->var_part[0].loc_chain->loc = loc;
1934   var->var_part[0].cur_loc = loc;
1935   variable_was_changed (var, set->vars);
1936 }
1937
1938 /* Set the part of variable's location in the dataflow set SET.  The variable
1939    part is specified by variable's declaration DECL and offset OFFSET and the
1940    part's location by LOC.  */
1941
1942 static void
1943 set_variable_part (dataflow_set *set, rtx loc, tree decl, HOST_WIDE_INT offset)
1944 {
1945   int pos, low, high;
1946   location_chain node, next;
1947   location_chain *nextp;
1948   variable var;
1949   void **slot;
1950
1951   slot = htab_find_slot_with_hash (set->vars, decl,
1952                                    VARIABLE_HASH_VAL (decl), INSERT);
1953   if (!*slot)
1954     {
1955       /* Create new variable information.  */
1956       var = pool_alloc (var_pool);
1957       var->decl = decl;
1958       var->refcount = 1;
1959       var->n_var_parts = 1;
1960       var->var_part[0].offset = offset;
1961       var->var_part[0].loc_chain = NULL;
1962       var->var_part[0].cur_loc = NULL;
1963       *slot = var;
1964       pos = 0;
1965     }
1966   else
1967     {
1968       var = (variable) *slot;
1969
1970       /* Find the location part.  */
1971       low = 0;
1972       high = var->n_var_parts;
1973       while (low != high)
1974         {
1975           pos = (low + high) / 2;
1976           if (var->var_part[pos].offset < offset)
1977             low = pos + 1;
1978           else
1979             high = pos;
1980         }
1981       pos = low;
1982
1983       if (pos < var->n_var_parts && var->var_part[pos].offset == offset)
1984         {
1985           node = var->var_part[pos].loc_chain;
1986
1987           if (node
1988               && ((REG_P (node->loc) && REG_P (loc)
1989                    && REGNO (node->loc) == REGNO (loc))
1990                   || rtx_equal_p (node->loc, loc)))
1991             {
1992               /* LOC is in the beginning of the chain so we have nothing
1993                  to do.  */
1994               return;
1995             }
1996           else
1997             {
1998               /* We have to make a copy of a shared variable.  */
1999               if (var->refcount > 1)
2000                 var = unshare_variable (set, var);
2001             }
2002         }
2003       else
2004         {
2005           /* We have not found the location part, new one will be created.  */
2006
2007           /* We have to make a copy of the shared variable.  */
2008           if (var->refcount > 1)
2009             var = unshare_variable (set, var);
2010
2011           /* We track only variables whose size is <= MAX_VAR_PARTS bytes
2012              thus there are at most MAX_VAR_PARTS different offsets.  */
2013           gcc_assert (var->n_var_parts < MAX_VAR_PARTS);
2014
2015           /* We have to move the elements of array starting at index low to the
2016              next position.  */
2017           for (high = var->n_var_parts; high > low; high--)
2018             var->var_part[high] = var->var_part[high - 1];
2019
2020           var->n_var_parts++;
2021           var->var_part[pos].offset = offset;
2022           var->var_part[pos].loc_chain = NULL;
2023           var->var_part[pos].cur_loc = NULL;
2024         }
2025     }
2026
2027   /* Delete the location from the list.  */
2028   nextp = &var->var_part[pos].loc_chain;
2029   for (node = var->var_part[pos].loc_chain; node; node = next)
2030     {
2031       next = node->next;
2032       if ((REG_P (node->loc) && REG_P (loc)
2033            && REGNO (node->loc) == REGNO (loc))
2034           || rtx_equal_p (node->loc, loc))
2035         {
2036           pool_free (loc_chain_pool, node);
2037           *nextp = next;
2038           break;
2039         }
2040       else
2041         nextp = &node->next;
2042     }
2043
2044   /* Add the location to the beginning.  */
2045   node = pool_alloc (loc_chain_pool);
2046   node->loc = loc;
2047   node->next = var->var_part[pos].loc_chain;
2048   var->var_part[pos].loc_chain = node;
2049
2050   /* If no location was emitted do so.  */
2051   if (var->var_part[pos].cur_loc == NULL)
2052     {
2053       var->var_part[pos].cur_loc = loc;
2054       variable_was_changed (var, set->vars);
2055     }
2056 }
2057
2058 /* Delete the part of variable's location from dataflow set SET.  The variable
2059    part is specified by variable's declaration DECL and offset OFFSET and the
2060    part's location by LOC.  */
2061
2062 static void
2063 delete_variable_part (dataflow_set *set, rtx loc, tree decl,
2064                       HOST_WIDE_INT offset)
2065 {
2066   int pos, low, high;
2067   void **slot;
2068
2069   slot = htab_find_slot_with_hash (set->vars, decl, VARIABLE_HASH_VAL (decl),
2070                                    NO_INSERT);
2071   if (slot)
2072     {
2073       variable var = (variable) *slot;
2074
2075       /* Find the location part.  */
2076       low = 0;
2077       high = var->n_var_parts;
2078       while (low != high)
2079         {
2080           pos = (low + high) / 2;
2081           if (var->var_part[pos].offset < offset)
2082             low = pos + 1;
2083           else
2084             high = pos;
2085         }
2086       pos = low;
2087
2088       if (pos < var->n_var_parts && var->var_part[pos].offset == offset)
2089         {
2090           location_chain node, next;
2091           location_chain *nextp;
2092           bool changed;
2093
2094           if (var->refcount > 1)
2095             {
2096               /* If the variable contains the location part we have to
2097                  make a copy of the variable.  */
2098               for (node = var->var_part[pos].loc_chain; node;
2099                    node = node->next)
2100                 {
2101                   if ((REG_P (node->loc) && REG_P (loc)
2102                        && REGNO (node->loc) == REGNO (loc))
2103                       || rtx_equal_p (node->loc, loc))
2104                     {
2105                       var = unshare_variable (set, var);
2106                       break;
2107                     }
2108                 }
2109             }
2110
2111           /* Delete the location part.  */
2112           nextp = &var->var_part[pos].loc_chain;
2113           for (node = *nextp; node; node = next)
2114             {
2115               next = node->next;
2116               if ((REG_P (node->loc) && REG_P (loc)
2117                    && REGNO (node->loc) == REGNO (loc))
2118                   || rtx_equal_p (node->loc, loc))
2119                 {
2120                   pool_free (loc_chain_pool, node);
2121                   *nextp = next;
2122                   break;
2123                 }
2124               else
2125                 nextp = &node->next;
2126             }
2127
2128           /* If we have deleted the location which was last emitted
2129              we have to emit new location so add the variable to set
2130              of changed variables.  */
2131           if (var->var_part[pos].cur_loc
2132               && ((REG_P (loc)
2133                    && REG_P (var->var_part[pos].cur_loc)
2134                    && REGNO (loc) == REGNO (var->var_part[pos].cur_loc))
2135                   || rtx_equal_p (loc, var->var_part[pos].cur_loc)))
2136             {
2137               changed = true;
2138               if (var->var_part[pos].loc_chain)
2139                 var->var_part[pos].cur_loc = var->var_part[pos].loc_chain->loc;
2140             }
2141           else
2142             changed = false;
2143
2144           if (var->var_part[pos].loc_chain == NULL)
2145             {
2146               var->n_var_parts--;
2147               while (pos < var->n_var_parts)
2148                 {
2149                   var->var_part[pos] = var->var_part[pos + 1];
2150                   pos++;
2151                 }
2152             }
2153           if (changed)
2154               variable_was_changed (var, set->vars);
2155         }
2156     }
2157 }
2158
2159 /* Emit the NOTE_INSN_VAR_LOCATION for variable *VARP.  DATA contains
2160    additional parameters: WHERE specifies whether the note shall be emitted
2161    before of after instruction INSN.  */
2162
2163 static int
2164 emit_note_insn_var_location (void **varp, void *data)
2165 {
2166   variable var = *(variable *) varp;
2167   rtx insn = ((emit_note_data *)data)->insn;
2168   enum emit_note_where where = ((emit_note_data *)data)->where;
2169   rtx note;
2170   int i;
2171   bool complete;
2172   HOST_WIDE_INT last_limit;
2173   tree type_size_unit;
2174
2175   gcc_assert (var->decl);
2176
2177   complete = true;
2178   last_limit = 0;
2179   for (i = 0; i < var->n_var_parts; i++)
2180     {
2181       if (last_limit < var->var_part[i].offset)
2182         {
2183           complete = false;
2184           break;
2185         }
2186       last_limit
2187         = (var->var_part[i].offset
2188            + GET_MODE_SIZE (GET_MODE (var->var_part[i].loc_chain->loc)));
2189     }
2190   type_size_unit = TYPE_SIZE_UNIT (TREE_TYPE (var->decl));
2191   if ((unsigned HOST_WIDE_INT) last_limit < TREE_INT_CST_LOW (type_size_unit))
2192     complete = false;
2193
2194   if (where == EMIT_NOTE_AFTER_INSN)
2195     note = emit_note_after (NOTE_INSN_VAR_LOCATION, insn);
2196   else
2197     note = emit_note_before (NOTE_INSN_VAR_LOCATION, insn);
2198
2199   if (!complete)
2200     {
2201       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2202                                                        NULL_RTX);
2203     }
2204   else if (var->n_var_parts == 1)
2205     {
2206       rtx expr_list
2207         = gen_rtx_EXPR_LIST (VOIDmode,
2208                              var->var_part[0].loc_chain->loc,
2209                              GEN_INT (var->var_part[0].offset));
2210
2211       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2212                                                        expr_list);
2213     }
2214   else if (var->n_var_parts)
2215     {
2216       rtx argp[MAX_VAR_PARTS];
2217       rtx parallel;
2218
2219       for (i = 0; i < var->n_var_parts; i++)
2220         argp[i] = gen_rtx_EXPR_LIST (VOIDmode, var->var_part[i].loc_chain->loc,
2221                                      GEN_INT (var->var_part[i].offset));
2222       parallel = gen_rtx_PARALLEL (VOIDmode,
2223                                    gen_rtvec_v (var->n_var_parts, argp));
2224       NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
2225                                                        parallel);
2226     }
2227
2228   htab_clear_slot (changed_variables, varp);
2229
2230   /* When there are no location parts the variable has been already
2231      removed from hash table and a new empty variable was created.
2232      Free the empty variable.  */
2233   if (var->n_var_parts == 0)
2234     {
2235       pool_free (var_pool, var);
2236     }
2237
2238   /* Continue traversing the hash table.  */
2239   return 1;
2240 }
2241
2242 /* Emit NOTE_INSN_VAR_LOCATION note for each variable from a chain
2243    CHANGED_VARIABLES and delete this chain.  WHERE specifies whether the notes
2244    shall be emitted before of after instruction INSN.  */
2245
2246 static void
2247 emit_notes_for_changes (rtx insn, enum emit_note_where where)
2248 {
2249   emit_note_data data;
2250
2251   data.insn = insn;
2252   data.where = where;
2253   htab_traverse (changed_variables, emit_note_insn_var_location, &data);
2254 }
2255
2256 /* Add variable *SLOT to the chain CHANGED_VARIABLES if it differs from the
2257    same variable in hash table DATA or is not there at all.  */
2258
2259 static int
2260 emit_notes_for_differences_1 (void **slot, void *data)
2261 {
2262   htab_t new_vars = (htab_t) data;
2263   variable old_var, new_var;
2264
2265   old_var = *(variable *) slot;
2266   new_var = htab_find_with_hash (new_vars, old_var->decl,
2267                                  VARIABLE_HASH_VAL (old_var->decl));
2268
2269   if (!new_var)
2270     {
2271       /* Variable has disappeared.  */
2272       variable empty_var;
2273
2274       empty_var = pool_alloc (var_pool);
2275       empty_var->decl = old_var->decl;
2276       empty_var->refcount = 1;
2277       empty_var->n_var_parts = 0;
2278       variable_was_changed (empty_var, NULL);
2279     }
2280   else if (variable_different_p (old_var, new_var, true))
2281     {
2282       variable_was_changed (new_var, NULL);
2283     }
2284
2285   /* Continue traversing the hash table.  */
2286   return 1;
2287 }
2288
2289 /* Add variable *SLOT to the chain CHANGED_VARIABLES if it is not in hash
2290    table DATA.  */
2291
2292 static int
2293 emit_notes_for_differences_2 (void **slot, void *data)
2294 {
2295   htab_t old_vars = (htab_t) data;
2296   variable old_var, new_var;
2297
2298   new_var = *(variable *) slot;
2299   old_var = htab_find_with_hash (old_vars, new_var->decl,
2300                                  VARIABLE_HASH_VAL (new_var->decl));
2301   if (!old_var)
2302     {
2303       /* Variable has appeared.  */
2304       variable_was_changed (new_var, NULL);
2305     }
2306
2307   /* Continue traversing the hash table.  */
2308   return 1;
2309 }
2310
2311 /* Emit notes before INSN for differences between dataflow sets OLD_SET and
2312    NEW_SET.  */
2313
2314 static void
2315 emit_notes_for_differences (rtx insn, dataflow_set *old_set,
2316                             dataflow_set *new_set)
2317 {
2318   htab_traverse (old_set->vars, emit_notes_for_differences_1, new_set->vars);
2319   htab_traverse (new_set->vars, emit_notes_for_differences_2, old_set->vars);
2320   emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2321 }
2322
2323 /* Emit the notes for changes of location parts in the basic block BB.  */
2324
2325 static void
2326 emit_notes_in_bb (basic_block bb)
2327 {
2328   int i;
2329   dataflow_set set;
2330
2331   dataflow_set_init (&set, htab_elements (VTI (bb)->in.vars) + 3);
2332   dataflow_set_copy (&set, &VTI (bb)->in);
2333
2334   for (i = 0; i < VTI (bb)->n_mos; i++)
2335     {
2336       rtx insn = VTI (bb)->mos[i].insn;
2337
2338       switch (VTI (bb)->mos[i].type)
2339         {
2340           case MO_CALL:
2341             {
2342               int r;
2343
2344               for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
2345                 if (TEST_HARD_REG_BIT (call_used_reg_set, r))
2346                   {
2347                     var_regno_delete (&set, r);
2348                   }
2349               emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2350             }
2351             break;
2352
2353           case MO_USE:
2354           case MO_SET:
2355             {
2356               rtx loc = VTI (bb)->mos[i].u.loc;
2357
2358               if (REG_P (loc))
2359                 var_reg_delete_and_set (&set, loc);
2360               else
2361                 var_mem_delete_and_set (&set, loc);
2362
2363               if (VTI (bb)->mos[i].type == MO_USE)
2364                 emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2365               else
2366                 emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2367             }
2368             break;
2369
2370           case MO_USE_NO_VAR:
2371           case MO_CLOBBER:
2372             {
2373               rtx loc = VTI (bb)->mos[i].u.loc;
2374
2375               if (REG_P (loc))
2376                 var_reg_delete (&set, loc);
2377               else
2378                 var_mem_delete (&set, loc);
2379
2380               if (VTI (bb)->mos[i].type == MO_USE_NO_VAR)
2381                 emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
2382               else
2383                 emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2384             }
2385             break;
2386
2387           case MO_ADJUST:
2388             {
2389               rtx base;
2390
2391               set.stack_adjust += VTI (bb)->mos[i].u.adjust;
2392               base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
2393                                                         set.stack_adjust));
2394               set_frame_base_location (&set, base);
2395               emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
2396             }
2397             break;
2398         }
2399     }
2400   dataflow_set_destroy (&set);
2401 }
2402
2403 /* Emit notes for the whole function.  */
2404
2405 static void
2406 vt_emit_notes (void)
2407 {
2408   basic_block bb;
2409   dataflow_set *last_out;
2410   dataflow_set empty;
2411
2412   gcc_assert (!htab_elements (changed_variables));
2413
2414   /* Enable emitting notes by functions (mainly by set_variable_part and
2415      delete_variable_part).  */
2416   emit_notes = true;
2417
2418   dataflow_set_init (&empty, 7);
2419   last_out = &empty;
2420
2421   FOR_EACH_BB (bb)
2422     {
2423       /* Emit the notes for changes of variable locations between two
2424          subsequent basic blocks.  */
2425       emit_notes_for_differences (BB_HEAD (bb), last_out, &VTI (bb)->in);
2426
2427       /* Emit the notes for the changes in the basic block itself.  */
2428       emit_notes_in_bb (bb);
2429
2430       last_out = &VTI (bb)->out;
2431     }
2432   dataflow_set_destroy (&empty);
2433   emit_notes = false;
2434 }
2435
2436 /* If there is a declaration and offset associated with register/memory RTL
2437    assign declaration to *DECLP and offset to *OFFSETP, and return true.  */
2438
2439 static bool
2440 vt_get_decl_and_offset (rtx rtl, tree *declp, HOST_WIDE_INT *offsetp)
2441 {
2442   if (REG_P (rtl))
2443     {
2444       if (REG_ATTRS (rtl))
2445         {
2446           *declp = REG_EXPR (rtl);
2447           *offsetp = REG_OFFSET (rtl);
2448           return true;
2449         }
2450     }
2451   else if (MEM_P (rtl))
2452     {
2453       if (MEM_ATTRS (rtl))
2454         {
2455           *declp = MEM_EXPR (rtl);
2456           *offsetp = MEM_OFFSET (rtl) ? INTVAL (MEM_OFFSET (rtl)) : 0;
2457           return true;
2458         }
2459     }
2460   return false;
2461 }
2462
2463 /* Insert function parameters to IN and OUT sets of ENTRY_BLOCK.  */
2464
2465 static void
2466 vt_add_function_parameters (void)
2467 {
2468   tree parm;
2469
2470   for (parm = DECL_ARGUMENTS (current_function_decl);
2471        parm; parm = TREE_CHAIN (parm))
2472     {
2473       rtx decl_rtl = DECL_RTL_IF_SET (parm);
2474       rtx incoming = DECL_INCOMING_RTL (parm);
2475       tree decl;
2476       HOST_WIDE_INT offset;
2477       dataflow_set *out;
2478
2479       if (TREE_CODE (parm) != PARM_DECL)
2480         continue;
2481
2482       if (!DECL_NAME (parm))
2483         continue;
2484
2485       if (!decl_rtl || !incoming)
2486         continue;
2487
2488       if (GET_MODE (decl_rtl) == BLKmode || GET_MODE (incoming) == BLKmode)
2489         continue;
2490
2491       if (!vt_get_decl_and_offset (incoming, &decl, &offset))
2492         if (!vt_get_decl_and_offset (decl_rtl, &decl, &offset))
2493           continue;
2494
2495       if (!decl)
2496         continue;
2497
2498       gcc_assert (parm == decl);
2499
2500       incoming = eliminate_regs (incoming, 0, NULL_RTX);
2501       out = &VTI (ENTRY_BLOCK_PTR)->out;
2502
2503       if (REG_P (incoming))
2504         {
2505           gcc_assert (REGNO (incoming) < FIRST_PSEUDO_REGISTER);
2506           attrs_list_insert (&out->regs[REGNO (incoming)],
2507                              parm, offset, incoming);
2508           set_variable_part (out, incoming, parm, offset);
2509         }
2510       else if (MEM_P (incoming))
2511         {
2512           set_variable_part (out, incoming, parm, offset);
2513         }
2514     }
2515 }
2516
2517 /* Allocate and initialize the data structures for variable tracking
2518    and parse the RTL to get the micro operations.  */
2519
2520 static void
2521 vt_initialize (void)
2522 {
2523   basic_block bb;
2524
2525   alloc_aux_for_blocks (sizeof (struct variable_tracking_info_def));
2526
2527   FOR_EACH_BB (bb)
2528     {
2529       rtx insn;
2530       HOST_WIDE_INT pre, post;
2531
2532       /* Count the number of micro operations.  */
2533       VTI (bb)->n_mos = 0;
2534       for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
2535            insn = NEXT_INSN (insn))
2536         {
2537           if (INSN_P (insn))
2538             {
2539               if (!frame_pointer_needed)
2540                 {
2541                   insn_stack_adjust_offset_pre_post (insn, &pre, &post);
2542                   if (pre)
2543                     VTI (bb)->n_mos++;
2544                   if (post)
2545                     VTI (bb)->n_mos++;
2546                 }
2547               note_uses (&PATTERN (insn), count_uses_1, insn);
2548               note_stores (PATTERN (insn), count_stores, insn);
2549               if (CALL_P (insn))
2550                 VTI (bb)->n_mos++;
2551             }
2552         }
2553
2554       /* Add the micro-operations to the array.  */
2555       VTI (bb)->mos = xmalloc (VTI (bb)->n_mos
2556                                * sizeof (struct micro_operation_def));
2557       VTI (bb)->n_mos = 0;
2558       for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
2559            insn = NEXT_INSN (insn))
2560         {
2561           if (INSN_P (insn))
2562             {
2563               int n1, n2;
2564
2565               if (!frame_pointer_needed)
2566                 {
2567                   insn_stack_adjust_offset_pre_post (insn, &pre, &post);
2568                   if (pre)
2569                     {
2570                       micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2571
2572                       mo->type = MO_ADJUST;
2573                       mo->u.adjust = pre;
2574                       mo->insn = insn;
2575                     }
2576                 }
2577
2578               n1 = VTI (bb)->n_mos;
2579               note_uses (&PATTERN (insn), add_uses_1, insn);
2580               n2 = VTI (bb)->n_mos - 1;
2581
2582               /* Order the MO_USEs to be before MO_USE_NO_VARs.  */
2583               while (n1 < n2)
2584                 {
2585                   while (n1 < n2 && VTI (bb)->mos[n1].type == MO_USE)
2586                     n1++;
2587                   while (n1 < n2 && VTI (bb)->mos[n2].type == MO_USE_NO_VAR)
2588                     n2--;
2589                   if (n1 < n2)
2590                     {
2591                       micro_operation sw;
2592
2593                       sw = VTI (bb)->mos[n1];
2594                       VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
2595                       VTI (bb)->mos[n2] = sw;
2596                     }
2597                 }
2598
2599               if (CALL_P (insn))
2600                 {
2601                   micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2602
2603                   mo->type = MO_CALL;
2604                   mo->insn = insn;
2605                 }
2606
2607               n1 = VTI (bb)->n_mos;
2608               note_stores (PATTERN (insn), add_stores, insn);
2609               n2 = VTI (bb)->n_mos - 1;
2610
2611               /* Order the MO_SETs to be before MO_CLOBBERs.  */
2612               while (n1 < n2)
2613                 {
2614                   while (n1 < n2 && VTI (bb)->mos[n1].type == MO_SET)
2615                     n1++;
2616                   while (n1 < n2 && VTI (bb)->mos[n2].type == MO_CLOBBER)
2617                     n2--;
2618                   if (n1 < n2)
2619                     {
2620                       micro_operation sw;
2621
2622                       sw = VTI (bb)->mos[n1];
2623                       VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
2624                       VTI (bb)->mos[n2] = sw;
2625                     }
2626                 }
2627
2628               if (!frame_pointer_needed && post)
2629                 {
2630                   micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;
2631
2632                   mo->type = MO_ADJUST;
2633                   mo->u.adjust = post;
2634                   mo->insn = insn;
2635                 }
2636             }
2637         }
2638     }
2639
2640   /* Init the IN and OUT sets.  */
2641   FOR_ALL_BB (bb)
2642     {
2643       VTI (bb)->visited = false;
2644       dataflow_set_init (&VTI (bb)->in, 7);
2645       dataflow_set_init (&VTI (bb)->out, 7);
2646     }
2647
2648   attrs_pool = create_alloc_pool ("attrs_def pool",
2649                                   sizeof (struct attrs_def), 1024);
2650   var_pool = create_alloc_pool ("variable_def pool",
2651                                 sizeof (struct variable_def), 64);
2652   loc_chain_pool = create_alloc_pool ("location_chain_def pool",
2653                                       sizeof (struct location_chain_def),
2654                                       1024);
2655   changed_variables = htab_create (10, variable_htab_hash, variable_htab_eq,
2656                                    NULL);
2657   vt_add_function_parameters ();
2658
2659   if (!frame_pointer_needed)
2660     {
2661       rtx base;
2662
2663       /* Create fake variable for tracking stack pointer changes.  */
2664       frame_base_decl = make_node (VAR_DECL);
2665       DECL_NAME (frame_base_decl) = get_identifier ("___frame_base_decl");
2666       TREE_TYPE (frame_base_decl) = char_type_node;
2667       DECL_ARTIFICIAL (frame_base_decl) = 1;
2668       DECL_IGNORED_P (frame_base_decl) = 1;
2669
2670       /* Set its initial "location".  */
2671       frame_stack_adjust = -prologue_stack_adjust ();
2672       base = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
2673                                                 frame_stack_adjust));
2674       set_variable_part (&VTI (ENTRY_BLOCK_PTR)->out, base, frame_base_decl, 0);
2675     }
2676   else
2677     {
2678       frame_base_decl = NULL;
2679     }
2680 }
2681
2682 /* Free the data structures needed for variable tracking.  */
2683
2684 static void
2685 vt_finalize (void)
2686 {
2687   basic_block bb;
2688
2689   FOR_EACH_BB (bb)
2690     {
2691       free (VTI (bb)->mos);
2692     }
2693
2694   FOR_ALL_BB (bb)
2695     {
2696       dataflow_set_destroy (&VTI (bb)->in);
2697       dataflow_set_destroy (&VTI (bb)->out);
2698     }
2699   free_aux_for_blocks ();
2700   free_alloc_pool (attrs_pool);
2701   free_alloc_pool (var_pool);
2702   free_alloc_pool (loc_chain_pool);
2703   htab_delete (changed_variables);
2704 }
2705
2706 /* The entry point to variable tracking pass.  */
2707
2708 void
2709 variable_tracking_main (void)
2710 {
2711   if (n_basic_blocks > 500 && n_edges / n_basic_blocks >= 20)
2712     return;
2713
2714   mark_dfs_back_edges ();
2715   vt_initialize ();
2716   if (!frame_pointer_needed)
2717     {
2718       if (!vt_stack_adjustments ())
2719         {
2720           vt_finalize ();
2721           return;
2722         }
2723     }
2724
2725   vt_find_locations ();
2726   vt_emit_notes ();
2727
2728   if (dump_file)
2729     {
2730       dump_dataflow_sets ();
2731       dump_flow_info (dump_file);
2732     }
2733
2734   vt_finalize ();
2735 }