gcc/tree-flow.h

   1 /* Data and Control Flow Analysis for Trees.
   2    Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
   3    Contributed by Diego Novillo <dnovillo@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #ifndef _TREE_FLOW_H
  23 #define _TREE_FLOW_H 1
  24
  25 #include "bitmap.h"
  26 #include "hard-reg-set.h"
  27 #include "basic-block.h"
  28 #include "hashtab.h"
  29 #include "tree-gimple.h"
  30 #include "tree-ssa-operands.h"
  31
  32 /* Forward declare structures for the garbage collector GTY markers.  */
  33 #ifndef GCC_BASIC_BLOCK_H
  34 struct edge_def;
  35 typedef struct edge_def *edge;
  36 struct basic_block_def;
  37 typedef struct basic_block_def *basic_block;
  38 #endif
  39
  40 /*---------------------------------------------------------------------------
  41                    Tree annotations stored in tree_common.ann
  42 ---------------------------------------------------------------------------*/
  43 enum tree_ann_type { TREE_ANN_COMMON, VAR_ANN, STMT_ANN };
  44
  45 struct tree_ann_common_d GTY(())
  46 {
  47   /* Annotation type.  */
  48   enum tree_ann_type type;
  49 };
  50
  51 /* It is advantageous to avoid things like life analysis for variables which
  52    do not need PHI nodes.  This enum describes whether or not a particular
  53    variable may need a PHI node.  */
  54
  55 enum need_phi_state {
  56   /* This is the default.  If we are still in this state after finding
  57      all the definition and use sites, then we will assume the variable
  58      needs PHI nodes.  This is probably an overly conservative assumption.  */
  59   NEED_PHI_STATE_UNKNOWN,
  60
  61   /* This state indicates that we have seen one or more sets of the
  62      variable in a single basic block and that the sets dominate all
  63      uses seen so far.  If after finding all definition and use sites
  64      we are still in this state, then the variable does not need any
  65      PHI nodes.  */
  66   NEED_PHI_STATE_NO,
  67
  68   /* This state indicates that we have either seen multiple definitions of
  69      the variable in multiple blocks, or that we encountered a use in a
  70      block that was not dominated by the block containing the set(s) of
  71      this variable.  This variable is assumed to need PHI nodes.  */
  72   NEED_PHI_STATE_MAYBE
  73 };
  74
  75
  76 /* When computing aliasing information, we represent the memory pointed-to
  77    by pointers with artificial variables called "memory tags" (MT).  There
  78    are two kinds of tags: type and name.  Type tags (TMT) are used in
  79    type-based alias analysis, they represent all the pointed-to locations
  80    and variables of the same alias set class.  Name tags (NMT) are used in
  81    flow-sensitive points-to alias analysis, they represent the variables
  82    and memory locations pointed-to by a specific SSA_NAME pointer.  */
  83 enum mem_tag_kind {
  84   /* This variable is not a memory tag.  */
  85   NOT_A_TAG,
  86
  87   /* This variable is a type memory tag (TMT).  */
  88   TYPE_TAG,
  89
  90   /* This variable is a name memory tag (NMT).  */
  91   NAME_TAG
  92 };
  93
  94 struct var_ann_d GTY(())
  95 {
  96   struct tree_ann_common_d common;
  97
  98   /* Nonzero if this variable has uses which may not appear
  99      in the IL.  This can happen in the following cases:
 100
 101        1. If the variable is used in a variable length
 102           array declaration.
 103
 104         2. If the variable is the return value in a C++
 105            function where the named return value optimization
 106            has been performed.  */
 107   unsigned has_hidden_use : 1;
 108
 109   /* Used by the out of SSA pass to determine whether this variable has
 110      been seen yet or not.  */
 111   unsigned out_of_ssa_tag : 1;
 112
 113   /* Used when building root_var structures in tree_ssa_live.[ch].  */
 114   unsigned root_var_processed : 1;
 115
 116   /* If nonzero, this variable is a memory tag.  */
 117   ENUM_BITFIELD (mem_tag_kind) mem_tag_kind : 2;
 118
 119   /* Nonzero if this variable is an alias tag that represents references to
 120      other variables (i.e., this variable appears in the MAY_ALIASES array
 121      of other variables).  */
 122   unsigned is_alias_tag : 1;
 123
 124   /* Nonzero if this variable was used after SSA optimizations were
 125      applied.  We set this when translating out of SSA form.  */
 126   unsigned used : 1;
 127
 128   /* This field indicates whether or not the variable may need PHI nodes.
 129      See the enum's definition for more detailed information about the
 130      states.  */
 131   ENUM_BITFIELD (need_phi_state) need_phi_state : 2;
 132
 133   /* An artificial variable representing the memory location pointed-to by
 134      all the pointers that TBAA (type-based alias analysis) considers
 135      to be aliased.  If the variable is not a pointer or if it is never
 136      dereferenced, this must be NULL.  */
 137   tree type_mem_tag;
 138
 139   /* Variables that may alias this variable.  */
 140   varray_type may_aliases;
 141
 142   /* Unique ID of this variable.  */
 143   size_t uid;
 144
 145   /* Used when going out of SSA form to indicate which partition this
 146      variable represents storage for.  */
 147   unsigned partition;
 148
 149   /* Used by the root-var object in tree-ssa-live.[ch].  */
 150   unsigned root_index;
 151
 152   /* Default definition for this symbol.  If this field is not NULL, it
 153      means that the first reference to this variable in the function is a
 154      USE or a VUSE.  In those cases, the SSA renamer creates an SSA name
 155      for this variable with an empty defining statement.  */
 156   tree default_def;
 157
 158   /* During into-ssa and the dominator optimizer, this field holds the
 159      current version of this variable (an SSA_NAME).
 160
 161      This was previously two varrays (one in into-ssa the other in the
 162      dominator optimizer).  That is wasteful, particularly since the
 163      dominator optimizer calls into-ssa resulting in having two varrays
 164      live at the same time and this can happen for each call to the
 165      dominator optimizer.  */
 166   tree current_def;
 167 };
 168
 169
 170 struct dataflow_d GTY(())
 171 {
 172   /* Immediate uses.  This is a list of all the statements and PHI nodes
 173      that are immediately reached by the definitions made in this
 174      statement.  */
 175   varray_type immediate_uses;
 176
 177   /* Use this array for very small numbers of uses instead of the varray.  */
 178   tree uses[2];
 179
 180   /* Reached uses.  This is a list of all the possible program statements
 181      that may be reached directly or indirectly by definitions made in this
 182      statement.  Notice that this is a superset of IMMEDIATE_USES.
 183      For instance, given the following piece of code:
 184
 185             1   a1 = 10;
 186             2   if (a1 > 3)
 187             3     a2 = a1 + 5;
 188             4   a3 = PHI (a1, a2)
 189             5   b1 = a3 - 2;
 190
 191      IMMEDIATE_USES for statement #1 are all those statements that use a1
 192      directly (i.e., #2, #3 and #4).  REACHED_USES for statement #1 also
 193      includes statement #5 because 'a1' could reach 'a3' via the PHI node
 194      at statement #4.  The set of REACHED_USES is then the transitive
 195      closure over all the PHI nodes in the IMMEDIATE_USES set.  */
 196
 197   /* Reaching definitions.  Similarly to REACHED_USES, the set
 198      REACHING_DEFS is the set of all the statements that make definitions
 199      that may reach this statement.  Notice that we don't need to have a
 200      similar entry for immediate definitions, as these are represented by
 201      the SSA_NAME nodes themselves (each SSA_NAME node contains a pointer
 202      to the statement that makes that definition).  */
 203 };
 204
 205 typedef struct dataflow_d *dataflow_t;
 206
 207
 208 struct stmt_ann_d GTY(())
 209 {
 210   struct tree_ann_common_d common;
 211
 212   /* Nonzero if the statement has been modified (meaning that the operands
 213      need to be scanned again).  */
 214   unsigned modified : 1;
 215
 216   /* Nonzero if the statement is in the CCP worklist and has not been
 217      "cancelled".  If we ever need to use this bit outside CCP, then
 218      it should be renamed.  */
 219   unsigned in_ccp_worklist: 1;
 220
 221   /* Nonzero if the statement makes aliased loads.  */
 222   unsigned makes_aliased_loads : 1;
 223
 224   /* Nonzero if the statement makes aliased stores.  */
 225   unsigned makes_aliased_stores : 1;
 226
 227   /* Nonzero if the statement makes references to volatile storage.  */
 228   unsigned has_volatile_ops : 1;
 229
 230   /* Nonzero if the statement makes a function call that may clobber global
 231      and local addressable variables.  */
 232   unsigned makes_clobbering_call : 1;
 233
 234   /* Basic block that contains this statement.  */
 235   basic_block GTY ((skip (""))) bb;
 236
 237   /* Statement operands.  */
 238   struct def_optype_d * GTY (()) def_ops;
 239   struct use_optype_d * GTY (()) use_ops;
 240
 241   /* Virtual operands (VDEF and VUSE).  */
 242   struct vdef_optype_d * GTY (()) vdef_ops;
 243   struct vuse_optype_d * GTY (()) vuse_ops;
 244
 245   /* Dataflow information.  */
 246   dataflow_t df;
 247
 248   /* Set of variables that have had their address taken in the statement.  */
 249   bitmap addresses_taken;
 250
 251   /* Unique identifier for this statement.  These ID's are to be created
 252      by each pass on an as-needed basis in any order convenient for the
 253      pass which needs statement UIDs.  */
 254   unsigned int uid;
 255 };
 256
 257
 258 union tree_ann_d GTY((desc ("ann_type ((tree_ann)&%h)")))
 259 {
 260   struct tree_ann_common_d GTY((tag ("TREE_ANN_COMMON"))) common;
 261   struct var_ann_d GTY((tag ("VAR_ANN"))) decl;
 262   struct stmt_ann_d GTY((tag ("STMT_ANN"))) stmt;
 263 };
 264
 265 typedef union tree_ann_d *tree_ann;
 266 typedef struct var_ann_d *var_ann_t;
 267 typedef struct stmt_ann_d *stmt_ann_t;
 268
 269 static inline var_ann_t var_ann (tree);
 270 static inline var_ann_t get_var_ann (tree);
 271 static inline stmt_ann_t stmt_ann (tree);
 272 static inline stmt_ann_t get_stmt_ann (tree);
 273 static inline enum tree_ann_type ann_type (tree_ann);
 274 static inline basic_block bb_for_stmt (tree);
 275 extern void set_bb_for_stmt (tree, basic_block);
 276 static inline void modify_stmt (tree);
 277 static inline void unmodify_stmt (tree);
 278 static inline bool stmt_modified_p (tree);
 279 static inline varray_type may_aliases (tree);
 280 static inline int get_lineno (tree);
 281 static inline const char *get_filename (tree);
 282 static inline bool is_exec_stmt (tree);
 283 static inline bool is_label_stmt (tree);
 284 static inline vdef_optype get_vdef_ops (stmt_ann_t);
 285 static inline vuse_optype get_vuse_ops (stmt_ann_t);
 286 static inline use_optype get_use_ops (stmt_ann_t);
 287 static inline def_optype get_def_ops (stmt_ann_t);
 288 static inline bitmap addresses_taken (tree);
 289 static inline int num_immediate_uses (dataflow_t);
 290 static inline tree immediate_use (dataflow_t, int);
 291 static inline dataflow_t get_immediate_uses (tree);
 292 static inline bool has_hidden_use (tree);
 293 static inline void set_has_hidden_use (tree);
 294 static inline void set_default_def (tree, tree);
 295 static inline tree default_def (tree);
 296 static inline bool may_be_aliased (tree);
 297
 298 /*---------------------------------------------------------------------------
 299                   Structure representing predictions in tree level.
 300 ---------------------------------------------------------------------------*/
 301 struct edge_prediction GTY((chain_next ("%h.next")))
 302 {
 303   struct edge_prediction *next;
 304   edge edge;
 305   enum br_predictor predictor;
 306   int probability;
 307 };
 308
 309 /*---------------------------------------------------------------------------
 310                   Block annotations stored in basic_block.tree_annotations
 311 ---------------------------------------------------------------------------*/
 312 struct bb_ann_d GTY(())
 313 {
 314   /* Chain of PHI nodes for this block.  */
 315   tree phi_nodes;
 316
 317   /* Chain of EPHI nodes created in this block.  */
 318   tree ephi_nodes;
 319
 320   /* Number of predecessors for this block.  This is only valid during
 321      SSA rewriting.  It is not maintained after conversion into SSA form.  */
 322   int num_preds;
 323
 324   /* Nonzero if this block is forwardable during cfg cleanups.  This is also
 325      used to detect loops during cfg cleanups.  */
 326   unsigned forwardable: 1;
 327
 328   /* Nonzero if this block contains an escape point (see is_escape_site).  */
 329   unsigned has_escape_site : 1;
 330
 331   struct edge_prediction *predictions;
 332 };
 333
 334 typedef struct bb_ann_d *bb_ann_t;
 335
 336 /* Accessors for basic block annotations.  */
 337 static inline bb_ann_t bb_ann (basic_block);
 338 static inline tree phi_nodes (basic_block);
 339 static inline void set_phi_nodes (basic_block, tree);
 340
 341 /*---------------------------------------------------------------------------
 342                               Global declarations
 343 ---------------------------------------------------------------------------*/
 344 /* Array of all variables referenced in the function.  */
 345 extern GTY(()) varray_type referenced_vars;
 346
 347 #define num_referenced_vars VARRAY_ACTIVE_SIZE (referenced_vars)
 348 #define referenced_var(i) VARRAY_TREE (referenced_vars, i)
 349
 350 /* Artificial variable used to model the effects of function calls.  */
 351 extern GTY(()) tree global_var;
 352
 353 /* Call clobbered variables in the function.  If bit I is set, then
 354    REFERENCED_VARS (I) is call-clobbered.  */
 355 extern bitmap call_clobbered_vars;
 356
 357 /* 'true' after aliases have been computed (see compute_may_aliases).  */
 358 extern bool aliases_computed_p;
 359
 360 /* Macros for showing usage statistics.  */
 361 #define SCALE(x) ((unsigned long) ((x) < 1024*10        \
 362                   ? (x)                                 \
 363                   : ((x) < 1024*1024*10                 \
 364                      ? (x) / 1024                       \
 365                      : (x) / (1024*1024))))
 366
 367 #define LABEL(x) ((x) < 1024*10 ? 'b' : ((x) < 1024*1024*10 ? 'k' : 'M'))
 368
 369 #define PERCENT(x,y) ((float)(x) * 100.0 / (float)(y))
 370
 371
 372 /*---------------------------------------------------------------------------
 373                               Block iterators
 374 ---------------------------------------------------------------------------*/
 375
 376 typedef struct {
 377   tree_stmt_iterator tsi;
 378   basic_block bb;
 379 } block_stmt_iterator;
 380
 381 static inline block_stmt_iterator bsi_start (basic_block);
 382 static inline block_stmt_iterator bsi_last (basic_block);
 383 static inline bool bsi_end_p (block_stmt_iterator);
 384 static inline void bsi_next (block_stmt_iterator *);
 385 static inline void bsi_prev (block_stmt_iterator *);
 386 static inline tree bsi_stmt (block_stmt_iterator);
 387 static inline tree * bsi_stmt_ptr (block_stmt_iterator);
 388
 389 extern void bsi_remove (block_stmt_iterator *);
 390 extern void bsi_move_before (block_stmt_iterator *, block_stmt_iterator *);
 391 extern void bsi_move_after (block_stmt_iterator *, block_stmt_iterator *);
 392 extern void bsi_move_to_bb_end (block_stmt_iterator *, basic_block);
 393
 394 enum bsi_iterator_update
 395 {
 396   /* Note that these are intentionally in the same order as TSI_FOO.  They
 397      mean exactly the same as their TSI_* counterparts.  */
 398   BSI_NEW_STMT,
 399   BSI_SAME_STMT,
 400   BSI_CHAIN_START,
 401   BSI_CHAIN_END,
 402   BSI_CONTINUE_LINKING
 403 };
 404
 405 extern void bsi_insert_before (block_stmt_iterator *, tree,
 406                                enum bsi_iterator_update);
 407 extern void bsi_insert_after (block_stmt_iterator *, tree,
 408                               enum bsi_iterator_update);
 409
 410 extern void bsi_replace (const block_stmt_iterator *, tree, bool);
 411
 412 /*---------------------------------------------------------------------------
 413                               Function prototypes
 414 ---------------------------------------------------------------------------*/
 415 /* In tree-cfg.c  */
 416
 417 /* Location to track pending stmt for edge insertion.  */
 418 #define PENDING_STMT(e) ((e)->insns.t)
 419
 420 extern void delete_tree_cfg (void);
 421 extern void disband_implicit_edges (void);
 422 extern bool stmt_ends_bb_p (tree);
 423 extern bool is_ctrl_stmt (tree);
 424 extern bool is_ctrl_altering_stmt (tree);
 425 extern bool computed_goto_p (tree);
 426 extern bool simple_goto_p (tree);
 427 extern void tree_dump_bb (basic_block, FILE *, int);
 428 extern void debug_tree_bb (basic_block);
 429 extern basic_block debug_tree_bb_n (int);
 430 extern void dump_tree_cfg (FILE *, int);
 431 extern void debug_tree_cfg (int);
 432 extern void dump_cfg_stats (FILE *);
 433 extern void debug_cfg_stats (void);
 434 extern void debug_loop_ir (void);
 435 extern void print_loop_ir (FILE *);
 436 extern void cleanup_tree_cfg (void);
 437 extern tree first_stmt (basic_block);
 438 extern tree last_stmt (basic_block);
 439 extern tree *last_stmt_ptr (basic_block);
 440 extern tree last_and_only_stmt (basic_block);
 441 extern edge find_taken_edge (basic_block, tree);
 442 extern void cfg_remove_useless_stmts (void);
 443 extern edge thread_edge (edge, basic_block);
 444 extern basic_block label_to_block (tree);
 445 extern void tree_optimize_tail_calls (bool, enum tree_dump_index);
 446 extern edge tree_block_forwards_to (basic_block bb);
 447 extern void bsi_insert_on_edge (edge, tree);
 448 extern void bsi_commit_edge_inserts (int *);
 449 extern void notice_special_calls (tree);
 450 extern void clear_special_calls (void);
 451 extern void compute_dominance_frontiers (bitmap *);
 452 extern void verify_stmts (void);
 453 extern void extract_true_false_edges_from_block (basic_block, edge *, edge *);
 454
 455 /* In tree-pretty-print.c.  */
 456 extern void dump_generic_bb (FILE *, basic_block, int, int);
 457
 458 /* In tree-dfa.c  */
 459 extern var_ann_t create_var_ann (tree);
 460 extern stmt_ann_t create_stmt_ann (tree);
 461 extern tree create_phi_node (tree, basic_block);
 462 extern void add_phi_arg (tree *, tree, edge);
 463 extern void remove_phi_arg (tree, basic_block);
 464 extern void remove_phi_arg_num (tree, int);
 465 extern void remove_phi_node (tree, tree, basic_block);
 466 extern void remove_all_phi_nodes_for (bitmap);
 467 extern void dump_dfa_stats (FILE *);
 468 extern void debug_dfa_stats (void);
 469 extern void debug_referenced_vars (void);
 470 extern void dump_referenced_vars (FILE *);
 471 extern void dump_variable (FILE *, tree);
 472 extern void debug_variable (tree);
 473 extern void dump_immediate_uses (FILE *);
 474 extern void debug_immediate_uses (void);
 475 extern void dump_immediate_uses_for (FILE *, tree);
 476 extern void debug_immediate_uses_for (tree);
 477 extern void compute_immediate_uses (int, bool (*)(tree));
 478 extern void free_df (void);
 479 extern tree get_virtual_var (tree);
 480 extern void add_referenced_tmp_var (tree var);
 481 extern void mark_new_vars_to_rename (tree, bitmap);
 482 extern void redirect_immediate_uses (tree, tree);
 483 extern tree make_rename_temp (tree, const char *);
 484
 485 /* Flags used when computing reaching definitions and reached uses.  */
 486 #define TDFA_USE_OPS            1 << 0
 487 #define TDFA_USE_VOPS           1 << 1
 488
 489 /* In gimple-low.c  */
 490 struct lower_data;
 491 extern void lower_stmt_body (tree, struct lower_data *);
 492 extern void expand_used_vars (void);
 493 extern void record_vars (tree);
 494 extern bool block_may_fallthru (tree block);
 495
 496 /* In tree-ssa-alias.c  */
 497 extern void dump_may_aliases_for (FILE *, tree);
 498 extern void debug_may_aliases_for (tree);
 499 extern void dump_alias_info (FILE *);
 500 extern void debug_alias_info (void);
 501 extern void dump_points_to_info (FILE *);
 502 extern void debug_points_to_info (void);
 503
 504 /* Call-back function for walk_use_def_chains().  At each reaching
 505    definition, a function with this prototype is called.  */
 506 typedef bool (*walk_use_def_chains_fn) (tree, tree, void *);
 507
 508 /* In tree-ssa.c  */
 509 extern void init_tree_ssa (void);
 510 extern void rewrite_vars_out_of_ssa (bitmap);
 511 extern void dump_reaching_defs (FILE *);
 512 extern void debug_reaching_defs (void);
 513 extern void dump_tree_ssa (FILE *);
 514 extern void debug_tree_ssa (void);
 515 extern void debug_def_blocks (void);
 516 extern void dump_tree_ssa_stats (FILE *);
 517 extern void debug_tree_ssa_stats (void);
 518 extern void ssa_remove_edge (edge);
 519 extern edge ssa_redirect_edge (edge, basic_block);
 520 extern void set_is_used (tree);
 521 extern bool tree_ssa_useless_type_conversion (tree);
 522 extern bool tree_ssa_useless_type_conversion_1 (tree, tree);
 523 extern void verify_ssa (void);
 524 extern void delete_tree_ssa (void);
 525 extern void register_new_def (tree, varray_type *);
 526 extern void walk_use_def_chains (tree, walk_use_def_chains_fn, void *);
 527
 528 /* In tree-into-ssa.c  */
 529 extern void rewrite_into_ssa (void);
 530
 531 extern unsigned int highest_ssa_version;
 532
 533 /* In tree-ssa-pre.c  */
 534 extern void tree_perform_ssapre (tree, enum tree_dump_index);
 535
 536 /* In tree-ssa-ccp.c  */
 537 bool fold_stmt (tree *);
 538 tree widen_bitfield (tree, tree, tree);
 539
 540 /* In tree-ssa-dom.c  */
 541 extern void dump_dominator_optimization_stats (FILE *);
 542 extern void debug_dominator_optimization_stats (void);
 543
 544 /* In tree-ssa-copy.c  */
 545 extern void propagate_value (tree *, tree);
 546 extern void replace_exp (tree *, tree);
 547 extern bool cprop_into_stmt (tree, varray_type);
 548 extern void cprop_into_successor_phis (basic_block, varray_type, bitmap);
 549
 550 /* In tree-flow-inline.h  */
 551 static inline int phi_arg_from_edge (tree, edge);
 552 static inline struct phi_arg_d *phi_element_for_edge (tree, edge);
 553 static inline bool may_propagate_copy (tree, tree);
 554 static inline bool is_call_clobbered (tree);
 555 static inline void mark_call_clobbered (tree);
 556
 557 /* In tree-eh.c  */
 558 extern void make_eh_edges (tree);
 559 extern bool tree_could_trap_p (tree);
 560 extern bool tree_could_throw_p (tree);
 561 extern bool tree_can_throw_internal (tree);
 562 extern bool tree_can_throw_external (tree);
 563 extern void add_stmt_to_eh_region (tree, int);
 564
 565 #include "tree-flow-inline.h"
 566
 567 #endif /* _TREE_FLOW_H  */