* gcc.dg/const-elim-1.c: xfail for xtensa.
[official-gcc.git] / gcc / sched-int.h
blobc8f3994b6de6d4e5e061cf89b466e66a8e010d93
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.
6 This file is part of GCC.
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.
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.
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. */
23 /* Pointer to data describing the current DFA state. */
24 extern state_t curr_state;
26 /* Forward declaration. */
27 struct ready_list;
29 /* Describe state of dependencies used during sched_analyze phase. */
30 struct deps
32 /* The *_insns and *_mems are paired lists. Each pending memory operation
33 will have a pointer to the MEM rtx on one list and a pointer to the
34 containing insn on the other list in the same place in the list. */
36 /* We can't use add_dependence like the old code did, because a single insn
37 may have multiple memory accesses, and hence needs to be on the list
38 once for each memory access. Add_dependence won't let you add an insn
39 to a list more than once. */
41 /* An INSN_LIST containing all insns with pending read operations. */
42 rtx pending_read_insns;
44 /* An EXPR_LIST containing all MEM rtx's which are pending reads. */
45 rtx pending_read_mems;
47 /* An INSN_LIST containing all insns with pending write operations. */
48 rtx pending_write_insns;
50 /* An EXPR_LIST containing all MEM rtx's which are pending writes. */
51 rtx pending_write_mems;
53 /* Indicates the combined length of the two pending lists. We must prevent
54 these lists from ever growing too large since the number of dependencies
55 produced is at least O(N*N), and execution time is at least O(4*N*N), as
56 a function of the length of these pending lists. */
57 int pending_lists_length;
59 /* Length of the pending memory flush list. Large functions with no
60 calls may build up extremely large lists. */
61 int pending_flush_length;
63 /* The last insn upon which all memory references must depend.
64 This is an insn which flushed the pending lists, creating a dependency
65 between it and all previously pending memory references. This creates
66 a barrier (or a checkpoint) which no memory reference is allowed to cross.
68 This includes all non constant CALL_INSNs. When we do interprocedural
69 alias analysis, this restriction can be relaxed.
70 This may also be an INSN that writes memory if the pending lists grow
71 too large. */
72 rtx last_pending_memory_flush;
74 /* A list of the last function calls we have seen. We use a list to
75 represent last function calls from multiple predecessor blocks.
76 Used to prevent register lifetimes from expanding unnecessarily. */
77 rtx last_function_call;
79 /* A list of insns which use a pseudo register that does not already
80 cross a call. We create dependencies between each of those insn
81 and the next call insn, to ensure that they won't cross a call after
82 scheduling is done. */
83 rtx sched_before_next_call;
85 /* Used to keep post-call pseudo/hard reg movements together with
86 the call. */
87 bool in_post_call_group_p;
89 /* Set to the tail insn of the outermost libcall block.
91 When nonzero, we will mark each insn processed by sched_analyze_insn
92 with SCHED_GROUP_P to ensure libcalls are scheduled as a unit. */
93 rtx libcall_block_tail_insn;
95 /* The maximum register number for the following arrays. Before reload
96 this is max_reg_num; after reload it is FIRST_PSEUDO_REGISTER. */
97 int max_reg;
99 /* Element N is the next insn that sets (hard or pseudo) register
100 N within the current basic block; or zero, if there is no
101 such insn. Needed for new registers which may be introduced
102 by splitting insns. */
103 struct deps_reg
105 rtx uses;
106 rtx sets;
107 rtx clobbers;
108 int uses_length;
109 int clobbers_length;
110 } *reg_last;
112 /* Element N is set for each register that has any nonzero element
113 in reg_last[N].{uses,sets,clobbers}. */
114 regset_head reg_last_in_use;
116 /* Element N is set for each register that is conditionally set. */
117 regset_head reg_conditional_sets;
120 /* This structure holds some state of the current scheduling pass, and
121 contains some function pointers that abstract out some of the non-generic
122 functionality from functions such as schedule_block or schedule_insn.
123 There is one global variable, current_sched_info, which points to the
124 sched_info structure currently in use. */
125 struct sched_info
127 /* Add all insns that are initially ready to the ready list. Called once
128 before scheduling a set of insns. */
129 void (*init_ready_list) (struct ready_list *);
130 /* Called after taking an insn from the ready list. Returns nonzero if
131 this insn can be scheduled, nonzero if we should silently discard it. */
132 int (*can_schedule_ready_p) (rtx);
133 /* Return nonzero if there are more insns that should be scheduled. */
134 int (*schedule_more_p) (void);
135 /* Called after an insn has all its dependencies resolved. Return nonzero
136 if it should be moved to the ready list or the queue, or zero if we
137 should silently discard it. */
138 int (*new_ready) (rtx);
139 /* Compare priority of two insns. Return a positive number if the second
140 insn is to be preferred for scheduling, and a negative one if the first
141 is to be preferred. Zero if they are equally good. */
142 int (*rank) (rtx, rtx);
143 /* Return a string that contains the insn uid and optionally anything else
144 necessary to identify this insn in an output. It's valid to use a
145 static buffer for this. The ALIGNED parameter should cause the string
146 to be formatted so that multiple output lines will line up nicely. */
147 const char *(*print_insn) (rtx, int);
148 /* Return nonzero if an insn should be included in priority
149 calculations. */
150 int (*contributes_to_priority) (rtx, rtx);
151 /* Called when computing dependencies for a JUMP_INSN. This function
152 should store the set of registers that must be considered as set by
153 the jump in the regset. */
154 void (*compute_jump_reg_dependencies) (rtx, regset, regset, regset);
156 /* The boundaries of the set of insns to be scheduled. */
157 rtx prev_head, next_tail;
159 /* Filled in after the schedule is finished; the first and last scheduled
160 insns. */
161 rtx head, tail;
163 /* If nonzero, enables an additional sanity check in schedule_block. */
164 unsigned int queue_must_finish_empty:1;
165 /* Nonzero if we should use cselib for better alias analysis. This
166 must be 0 if the dependency information is used after sched_analyze
167 has completed, e.g. if we're using it to initialize state for successor
168 blocks in region scheduling. */
169 unsigned int use_cselib:1;
171 /* Maximum priority that has been assigned to an insn. */
172 int sched_max_insns_priority;
175 extern struct sched_info *current_sched_info;
177 /* Indexed by INSN_UID, the collection of all data associated with
178 a single instruction. */
180 struct haifa_insn_data
182 /* A list of insns which depend on the instruction. Unlike LOG_LINKS,
183 it represents forward dependencies. */
184 rtx depend;
186 /* The line number note in effect for each insn. For line number
187 notes, this indicates whether the note may be reused. */
188 rtx line_note;
190 /* Logical uid gives the original ordering of the insns. */
191 int luid;
193 /* A priority for each insn. */
194 int priority;
196 /* The number of incoming edges in the forward dependency graph.
197 As scheduling proceeds, counts are decreased. An insn moves to
198 the ready queue when its counter reaches zero. */
199 int dep_count;
201 /* An encoding of the blockage range function. Both unit and range
202 are coded. This member is used only for old pipeline interface. */
203 unsigned int blockage;
205 /* Number of instructions referring to this insn. */
206 int ref_count;
208 /* The minimum clock tick at which the insn becomes ready. This is
209 used to note timing constraints for the insns in the pending list. */
210 int tick;
212 short cost;
214 /* An encoding of the function units used. This member is used only
215 for old pipeline interface. */
216 short units;
218 /* This weight is an estimation of the insn's contribution to
219 register pressure. */
220 short reg_weight;
222 /* Some insns (e.g. call) are not allowed to move across blocks. */
223 unsigned int cant_move : 1;
225 /* Set if there's DEF-USE dependence between some speculatively
226 moved load insn and this one. */
227 unsigned int fed_by_spec_load : 1;
228 unsigned int is_load_insn : 1;
230 /* Nonzero if priority has been computed already. */
231 unsigned int priority_known : 1;
234 extern struct haifa_insn_data *h_i_d;
236 /* Accessor macros for h_i_d. There are more in haifa-sched.c and
237 sched-rgn.c. */
238 #define INSN_DEPEND(INSN) (h_i_d[INSN_UID (INSN)].depend)
239 #define INSN_LUID(INSN) (h_i_d[INSN_UID (INSN)].luid)
240 #define CANT_MOVE(insn) (h_i_d[INSN_UID (insn)].cant_move)
241 #define INSN_DEP_COUNT(INSN) (h_i_d[INSN_UID (INSN)].dep_count)
242 #define INSN_PRIORITY(INSN) (h_i_d[INSN_UID (INSN)].priority)
243 #define INSN_PRIORITY_KNOWN(INSN) (h_i_d[INSN_UID (INSN)].priority_known)
244 #define INSN_COST(INSN) (h_i_d[INSN_UID (INSN)].cost)
245 #define INSN_UNIT(INSN) (h_i_d[INSN_UID (INSN)].units)
246 #define INSN_REG_WEIGHT(INSN) (h_i_d[INSN_UID (INSN)].reg_weight)
248 #define INSN_BLOCKAGE(INSN) (h_i_d[INSN_UID (INSN)].blockage)
249 #define UNIT_BITS 5
250 #define BLOCKAGE_MASK ((1 << BLOCKAGE_BITS) - 1)
251 #define ENCODE_BLOCKAGE(U, R) \
252 (((U) << BLOCKAGE_BITS \
253 | MIN_BLOCKAGE_COST (R)) << BLOCKAGE_BITS \
254 | MAX_BLOCKAGE_COST (R))
255 #define UNIT_BLOCKED(B) ((B) >> (2 * BLOCKAGE_BITS))
256 #define BLOCKAGE_RANGE(B) \
257 (((((B) >> BLOCKAGE_BITS) & BLOCKAGE_MASK) << (HOST_BITS_PER_INT / 2)) \
258 | ((B) & BLOCKAGE_MASK))
260 /* Encodings of the `<name>_unit_blockage_range' function. */
261 #define MIN_BLOCKAGE_COST(R) ((R) >> (HOST_BITS_PER_INT / 2))
262 #define MAX_BLOCKAGE_COST(R) ((R) & ((1 << (HOST_BITS_PER_INT / 2)) - 1))
264 extern FILE *sched_dump;
265 extern int sched_verbose;
267 /* Exception Free Loads:
269 We define five classes of speculative loads: IFREE, IRISKY,
270 PFREE, PRISKY, and MFREE.
272 IFREE loads are loads that are proved to be exception-free, just
273 by examining the load insn. Examples for such loads are loads
274 from TOC and loads of global data.
276 IRISKY loads are loads that are proved to be exception-risky,
277 just by examining the load insn. Examples for such loads are
278 volatile loads and loads from shared memory.
280 PFREE loads are loads for which we can prove, by examining other
281 insns, that they are exception-free. Currently, this class consists
282 of loads for which we are able to find a "similar load", either in
283 the target block, or, if only one split-block exists, in that split
284 block. Load2 is similar to load1 if both have same single base
285 register. We identify only part of the similar loads, by finding
286 an insn upon which both load1 and load2 have a DEF-USE dependence.
288 PRISKY loads are loads for which we can prove, by examining other
289 insns, that they are exception-risky. Currently we have two proofs for
290 such loads. The first proof detects loads that are probably guarded by a
291 test on the memory address. This proof is based on the
292 backward and forward data dependence information for the region.
293 Let load-insn be the examined load.
294 Load-insn is PRISKY iff ALL the following hold:
296 - insn1 is not in the same block as load-insn
297 - there is a DEF-USE dependence chain (insn1, ..., load-insn)
298 - test-insn is either a compare or a branch, not in the same block
299 as load-insn
300 - load-insn is reachable from test-insn
301 - there is a DEF-USE dependence chain (insn1, ..., test-insn)
303 This proof might fail when the compare and the load are fed
304 by an insn not in the region. To solve this, we will add to this
305 group all loads that have no input DEF-USE dependence.
307 The second proof detects loads that are directly or indirectly
308 fed by a speculative load. This proof is affected by the
309 scheduling process. We will use the flag fed_by_spec_load.
310 Initially, all insns have this flag reset. After a speculative
311 motion of an insn, if insn is either a load, or marked as
312 fed_by_spec_load, we will also mark as fed_by_spec_load every
313 insn1 for which a DEF-USE dependence (insn, insn1) exists. A
314 load which is fed_by_spec_load is also PRISKY.
316 MFREE (maybe-free) loads are all the remaining loads. They may be
317 exception-free, but we cannot prove it.
319 Now, all loads in IFREE and PFREE classes are considered
320 exception-free, while all loads in IRISKY and PRISKY classes are
321 considered exception-risky. As for loads in the MFREE class,
322 these are considered either exception-free or exception-risky,
323 depending on whether we are pessimistic or optimistic. We have
324 to take the pessimistic approach to assure the safety of
325 speculative scheduling, but we can take the optimistic approach
326 by invoking the -fsched_spec_load_dangerous option. */
328 enum INSN_TRAP_CLASS
330 TRAP_FREE = 0, IFREE = 1, PFREE_CANDIDATE = 2,
331 PRISKY_CANDIDATE = 3, IRISKY = 4, TRAP_RISKY = 5
334 #define WORST_CLASS(class1, class2) \
335 ((class1 > class2) ? class1 : class2)
337 #ifndef __GNUC__
338 #define __inline
339 #endif
341 #ifndef HAIFA_INLINE
342 #define HAIFA_INLINE __inline
343 #endif
345 /* Functions in sched-vis.c. */
346 extern void init_target_units (void);
347 extern void insn_print_units (rtx);
348 extern void init_block_visualization (void);
349 extern void print_block_visualization (const char *);
350 extern void visualize_scheduled_insns (int);
351 extern void visualize_no_unit (rtx);
352 extern void visualize_stall_cycles (int);
353 extern void visualize_alloc (void);
354 extern void visualize_free (void);
356 /* Functions in sched-deps.c. */
357 extern int add_dependence (rtx, rtx, enum reg_note);
358 extern void add_insn_mem_dependence (struct deps *, rtx *, rtx *, rtx, rtx);
359 extern void sched_analyze (struct deps *, rtx, rtx);
360 extern void init_deps (struct deps *);
361 extern void free_deps (struct deps *);
362 extern void init_deps_global (void);
363 extern void finish_deps_global (void);
364 extern void add_forward_dependence (rtx, rtx, enum reg_note);
365 extern void compute_forward_dependences (rtx, rtx);
366 extern rtx find_insn_list (rtx, rtx);
367 extern void init_dependency_caches (int);
368 extern void free_dependency_caches (void);
370 /* Functions in haifa-sched.c. */
371 extern int haifa_classify_insn (rtx);
372 extern void get_block_head_tail (int, rtx *, rtx *);
373 extern int no_real_insns_p (rtx, rtx);
375 extern void rm_line_notes (rtx, rtx);
376 extern void save_line_notes (int, rtx, rtx);
377 extern void restore_line_notes (rtx, rtx);
378 extern void rm_redundant_line_notes (void);
379 extern void rm_other_notes (rtx, rtx);
381 extern int insn_issue_delay (rtx);
382 extern int set_priorities (rtx, rtx);
384 extern void schedule_block (int, int);
385 extern void sched_init (FILE *);
386 extern void sched_finish (void);
388 extern void ready_add (struct ready_list *, rtx);
390 /* The following are exported for the benefit of debugging functions. It
391 would be nicer to keep them private to haifa-sched.c. */
392 extern int insn_unit (rtx);
393 extern int insn_cost (rtx, rtx, rtx);
394 extern rtx get_unit_last_insn (int);
395 extern int actual_hazard_this_instance (int, int, rtx, int, int);
396 extern void print_insn (char *, rtx, int);