gcc/sched-int.h

   1 /* Instruction scheduling pass.  This file contains definitions used
   2    internally in the scheduler.
   3    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   4    1999, 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to the Free
  20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  21 02111-1307, USA.  */
  22
  23 #ifndef GCC_SCHED_INT_H
  24 #define GCC_SCHED_INT_H
  25
  26 /* For state_t.  */
  27 #include "insn-attr.h"
  28 /* For regset_head.  */
  29 #include "basic-block.h"
  30 /* For reg_note.  */
  31 #include "rtl.h"
  32
  33 /* Pointer to data describing the current DFA state.  */
  34 extern state_t curr_state;
  35
  36 /* Forward declaration.  */
  37 struct ready_list;
  38
  39 /* Describe state of dependencies used during sched_analyze phase.  */
  40 struct deps
  41 {
  42   /* The *_insns and *_mems are paired lists.  Each pending memory operation
  43      will have a pointer to the MEM rtx on one list and a pointer to the
  44      containing insn on the other list in the same place in the list.  */
  45
  46   /* We can't use add_dependence like the old code did, because a single insn
  47      may have multiple memory accesses, and hence needs to be on the list
  48      once for each memory access.  Add_dependence won't let you add an insn
  49      to a list more than once.  */
  50
  51   /* An INSN_LIST containing all insns with pending read operations.  */
  52   rtx pending_read_insns;
  53
  54   /* An EXPR_LIST containing all MEM rtx's which are pending reads.  */
  55   rtx pending_read_mems;
  56
  57   /* An INSN_LIST containing all insns with pending write operations.  */
  58   rtx pending_write_insns;
  59
  60   /* An EXPR_LIST containing all MEM rtx's which are pending writes.  */
  61   rtx pending_write_mems;
  62
  63   /* Indicates the combined length of the two pending lists.  We must prevent
  64      these lists from ever growing too large since the number of dependencies
  65      produced is at least O(N*N), and execution time is at least O(4*N*N), as
  66      a function of the length of these pending lists.  */
  67   int pending_lists_length;
  68
  69   /* Length of the pending memory flush list. Large functions with no
  70      calls may build up extremely large lists.  */
  71   int pending_flush_length;
  72
  73   /* The last insn upon which all memory references must depend.
  74      This is an insn which flushed the pending lists, creating a dependency
  75      between it and all previously pending memory references.  This creates
  76      a barrier (or a checkpoint) which no memory reference is allowed to cross.
  77
  78      This includes all non constant CALL_INSNs.  When we do interprocedural
  79      alias analysis, this restriction can be relaxed.
  80      This may also be an INSN that writes memory if the pending lists grow
  81      too large.  */
  82   rtx last_pending_memory_flush;
  83
  84   /* A list of the last function calls we have seen.  We use a list to
  85      represent last function calls from multiple predecessor blocks.
  86      Used to prevent register lifetimes from expanding unnecessarily.  */
  87   rtx last_function_call;
  88
  89   /* A list of insns which use a pseudo register that does not already
  90      cross a call.  We create dependencies between each of those insn
  91      and the next call insn, to ensure that they won't cross a call after
  92      scheduling is done.  */
  93   rtx sched_before_next_call;
  94
  95   /* Used to keep post-call pseudo/hard reg movements together with
  96      the call.  */
  97   enum { not_post_call, post_call, post_call_initial } in_post_call_group_p;
  98
  99   /* Set to the tail insn of the outermost libcall block.
 100
 101      When nonzero, we will mark each insn processed by sched_analyze_insn
 102      with SCHED_GROUP_P to ensure libcalls are scheduled as a unit.  */
 103   rtx libcall_block_tail_insn;
 104
 105   /* The maximum register number for the following arrays.  Before reload
 106      this is max_reg_num; after reload it is FIRST_PSEUDO_REGISTER.  */
 107   int max_reg;
 108
 109   /* Element N is the next insn that sets (hard or pseudo) register
 110      N within the current basic block; or zero, if there is no
 111      such insn.  Needed for new registers which may be introduced
 112      by splitting insns.  */
 113   struct deps_reg
 114     {
 115       rtx uses;
 116       rtx sets;
 117       rtx clobbers;
 118       int uses_length;
 119       int clobbers_length;
 120     } *reg_last;
 121
 122   /* Element N is set for each register that has any nonzero element
 123      in reg_last[N].{uses,sets,clobbers}.  */
 124   regset_head reg_last_in_use;
 125
 126   /* Element N is set for each register that is conditionally set.  */
 127   regset_head reg_conditional_sets;
 128 };
 129
 130 /* This structure holds some state of the current scheduling pass, and
 131    contains some function pointers that abstract out some of the non-generic
 132    functionality from functions such as schedule_block or schedule_insn.
 133    There is one global variable, current_sched_info, which points to the
 134    sched_info structure currently in use.  */
 135 struct sched_info
 136 {
 137   /* Add all insns that are initially ready to the ready list.  Called once
 138      before scheduling a set of insns.  */
 139   void (*init_ready_list) (struct ready_list *);
 140   /* Called after taking an insn from the ready list.  Returns nonzero if
 141      this insn can be scheduled, nonzero if we should silently discard it.  */
 142   int (*can_schedule_ready_p) (rtx);
 143   /* Return nonzero if there are more insns that should be scheduled.  */
 144   int (*schedule_more_p) (void);
 145   /* Called after an insn has all its dependencies resolved.  Return nonzero
 146      if it should be moved to the ready list or the queue, or zero if we
 147      should silently discard it.  */
 148   int (*new_ready) (rtx);
 149   /* Compare priority of two insns.  Return a positive number if the second
 150      insn is to be preferred for scheduling, and a negative one if the first
 151      is to be preferred.  Zero if they are equally good.  */
 152   int (*rank) (rtx, rtx);
 153   /* Return a string that contains the insn uid and optionally anything else
 154      necessary to identify this insn in an output.  It's valid to use a
 155      static buffer for this.  The ALIGNED parameter should cause the string
 156      to be formatted so that multiple output lines will line up nicely.  */
 157   const char *(*print_insn) (rtx, int);
 158   /* Return nonzero if an insn should be included in priority
 159      calculations.  */
 160   int (*contributes_to_priority) (rtx, rtx);
 161   /* Called when computing dependencies for a JUMP_INSN.  This function
 162      should store the set of registers that must be considered as set by
 163      the jump in the regset.  */
 164   void (*compute_jump_reg_dependencies) (rtx, regset, regset, regset);
 165
 166   /* The boundaries of the set of insns to be scheduled.  */
 167   rtx prev_head, next_tail;
 168
 169   /* Filled in after the schedule is finished; the first and last scheduled
 170      insns.  */
 171   rtx head, tail;
 172
 173   /* If nonzero, enables an additional sanity check in schedule_block.  */
 174   unsigned int queue_must_finish_empty:1;
 175   /* Nonzero if we should use cselib for better alias analysis.  This
 176      must be 0 if the dependency information is used after sched_analyze
 177      has completed, e.g. if we're using it to initialize state for successor
 178      blocks in region scheduling.  */
 179   unsigned int use_cselib:1;
 180
 181   /* Maximum priority that has been assigned to an insn.  */
 182   int sched_max_insns_priority;
 183 };
 184
 185 extern struct sched_info *current_sched_info;
 186
 187 /* Indexed by INSN_UID, the collection of all data associated with
 188    a single instruction.  */
 189
 190 struct haifa_insn_data
 191 {
 192   /* A list of insns which depend on the instruction.  Unlike LOG_LINKS,
 193      it represents forward dependencies.  */
 194   rtx depend;
 195
 196   /* The line number note in effect for each insn.  For line number
 197      notes, this indicates whether the note may be reused.  */
 198   rtx line_note;
 199
 200   /* Logical uid gives the original ordering of the insns.  */
 201   int luid;
 202
 203   /* A priority for each insn.  */
 204   int priority;
 205
 206   /* The number of incoming edges in the forward dependency graph.
 207      As scheduling proceeds, counts are decreased.  An insn moves to
 208      the ready queue when its counter reaches zero.  */
 209   int dep_count;
 210
 211   /* Number of instructions referring to this insn.  */
 212   int ref_count;
 213
 214   /* The minimum clock tick at which the insn becomes ready.  This is
 215      used to note timing constraints for the insns in the pending list.  */
 216   int tick;
 217
 218   short cost;
 219
 220   /* This weight is an estimation of the insn's contribution to
 221      register pressure.  */
 222   short reg_weight;
 223
 224   /* Some insns (e.g. call) are not allowed to move across blocks.  */
 225   unsigned int cant_move : 1;
 226
 227   /* Set if there's DEF-USE dependence between some speculatively
 228      moved load insn and this one.  */
 229   unsigned int fed_by_spec_load : 1;
 230   unsigned int is_load_insn : 1;
 231
 232   /* Nonzero if priority has been computed already.  */
 233   unsigned int priority_known : 1;
 234 };
 235
 236 extern struct haifa_insn_data *h_i_d;
 237
 238 /* Accessor macros for h_i_d.  There are more in haifa-sched.c and
 239    sched-rgn.c.  */
 240 #define INSN_DEPEND(INSN)       (h_i_d[INSN_UID (INSN)].depend)
 241 #define INSN_LUID(INSN)         (h_i_d[INSN_UID (INSN)].luid)
 242 #define CANT_MOVE(insn)         (h_i_d[INSN_UID (insn)].cant_move)
 243 #define INSN_DEP_COUNT(INSN)    (h_i_d[INSN_UID (INSN)].dep_count)
 244 #define INSN_PRIORITY(INSN)     (h_i_d[INSN_UID (INSN)].priority)
 245 #define INSN_PRIORITY_KNOWN(INSN) (h_i_d[INSN_UID (INSN)].priority_known)
 246 #define INSN_COST(INSN)         (h_i_d[INSN_UID (INSN)].cost)
 247 #define INSN_REG_WEIGHT(INSN)   (h_i_d[INSN_UID (INSN)].reg_weight)
 248
 249 extern FILE *sched_dump;
 250 extern int sched_verbose;
 251
 252 /* Exception Free Loads:
 253
 254    We define five classes of speculative loads: IFREE, IRISKY,
 255    PFREE, PRISKY, and MFREE.
 256
 257    IFREE loads are loads that are proved to be exception-free, just
 258    by examining the load insn.  Examples for such loads are loads
 259    from TOC and loads of global data.
 260
 261    IRISKY loads are loads that are proved to be exception-risky,
 262    just by examining the load insn.  Examples for such loads are
 263    volatile loads and loads from shared memory.
 264
 265    PFREE loads are loads for which we can prove, by examining other
 266    insns, that they are exception-free.  Currently, this class consists
 267    of loads for which we are able to find a "similar load", either in
 268    the target block, or, if only one split-block exists, in that split
 269    block.  Load2 is similar to load1 if both have same single base
 270    register.  We identify only part of the similar loads, by finding
 271    an insn upon which both load1 and load2 have a DEF-USE dependence.
 272
 273    PRISKY loads are loads for which we can prove, by examining other
 274    insns, that they are exception-risky.  Currently we have two proofs for
 275    such loads.  The first proof detects loads that are probably guarded by a
 276    test on the memory address.  This proof is based on the
 277    backward and forward data dependence information for the region.
 278    Let load-insn be the examined load.
 279    Load-insn is PRISKY iff ALL the following hold:
 280
 281    - insn1 is not in the same block as load-insn
 282    - there is a DEF-USE dependence chain (insn1, ..., load-insn)
 283    - test-insn is either a compare or a branch, not in the same block
 284      as load-insn
 285    - load-insn is reachable from test-insn
 286    - there is a DEF-USE dependence chain (insn1, ..., test-insn)
 287
 288    This proof might fail when the compare and the load are fed
 289    by an insn not in the region.  To solve this, we will add to this
 290    group all loads that have no input DEF-USE dependence.
 291
 292    The second proof detects loads that are directly or indirectly
 293    fed by a speculative load.  This proof is affected by the
 294    scheduling process.  We will use the flag  fed_by_spec_load.
 295    Initially, all insns have this flag reset.  After a speculative
 296    motion of an insn, if insn is either a load, or marked as
 297    fed_by_spec_load, we will also mark as fed_by_spec_load every
 298    insn1 for which a DEF-USE dependence (insn, insn1) exists.  A
 299    load which is fed_by_spec_load is also PRISKY.
 300
 301    MFREE (maybe-free) loads are all the remaining loads. They may be
 302    exception-free, but we cannot prove it.
 303
 304    Now, all loads in IFREE and PFREE classes are considered
 305    exception-free, while all loads in IRISKY and PRISKY classes are
 306    considered exception-risky.  As for loads in the MFREE class,
 307    these are considered either exception-free or exception-risky,
 308    depending on whether we are pessimistic or optimistic.  We have
 309    to take the pessimistic approach to assure the safety of
 310    speculative scheduling, but we can take the optimistic approach
 311    by invoking the -fsched_spec_load_dangerous option.  */
 312
 313 enum INSN_TRAP_CLASS
 314 {
 315   TRAP_FREE = 0, IFREE = 1, PFREE_CANDIDATE = 2,
 316   PRISKY_CANDIDATE = 3, IRISKY = 4, TRAP_RISKY = 5
 317 };
 318
 319 #define WORST_CLASS(class1, class2) \
 320 ((class1 > class2) ? class1 : class2)
 321
 322 #ifndef __GNUC__
 323 #define __inline
 324 #endif
 325
 326 #ifndef HAIFA_INLINE
 327 #define HAIFA_INLINE __inline
 328 #endif
 329
 330 /* Functions in sched-vis.c.  */
 331 extern void print_insn (char *, rtx, int);
 332
 333 /* Functions in sched-deps.c.  */
 334 extern int add_dependence (rtx, rtx, enum reg_note);
 335 extern void sched_analyze (struct deps *, rtx, rtx);
 336 extern void init_deps (struct deps *);
 337 extern void free_deps (struct deps *);
 338 extern void init_deps_global (void);
 339 extern void finish_deps_global (void);
 340 extern void add_forward_dependence (rtx, rtx, enum reg_note);
 341 extern void compute_forward_dependences (rtx, rtx);
 342 extern rtx find_insn_list (rtx, rtx);
 343 extern void init_dependency_caches (int);
 344 extern void free_dependency_caches (void);
 345
 346 /* Functions in haifa-sched.c.  */
 347 extern int haifa_classify_insn (rtx);
 348 extern void get_block_head_tail (int, rtx *, rtx *);
 349 extern int no_real_insns_p (rtx, rtx);
 350
 351 extern void rm_line_notes (rtx, rtx);
 352 extern void save_line_notes (int, rtx, rtx);
 353 extern void restore_line_notes (rtx, rtx);
 354 extern void rm_redundant_line_notes (void);
 355 extern void rm_other_notes (rtx, rtx);
 356
 357 extern int insn_cost (rtx, rtx, rtx);
 358 extern int set_priorities (rtx, rtx);
 359
 360 extern void schedule_block (int, int);
 361 extern void sched_init (FILE *);
 362 extern void sched_finish (void);
 363
 364 extern void ready_add (struct ready_list *, rtx);
 365
 366 #endif /* GCC_SCHED_INT_H */