1 /* Communication between reload.cc, reload1.cc and the rest of compiler.
2 Copyright (C) 1987-2023 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 under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #ifndef GCC_RELOAD_H
21 #define GCC_RELOAD_H
22
23 /* If secondary reloads are the same for inputs and outputs, define those
24 macros here. */
25
26 #ifdef SECONDARY_RELOAD_CLASS
27 #define SECONDARY_INPUT_RELOAD_CLASS(CLASS, MODE, X) \
28 SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
29 #define SECONDARY_OUTPUT_RELOAD_CLASS(CLASS, MODE, X) \
30 SECONDARY_RELOAD_CLASS (CLASS, MODE, X)
31 #endif
32
33 extern int register_move_cost (machine_mode, reg_class_t, reg_class_t);
34 extern int memory_move_cost (machine_mode, reg_class_t, bool);
35 extern int memory_move_secondary_cost (machine_mode, reg_class_t, bool);
36
37 /* Maximum number of reloads we can need. */
38 #define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
39
40 /* Encode the usage of a reload. The following codes are supported:
41
42 RELOAD_FOR_INPUT reload of an input operand
43 RELOAD_FOR_OUTPUT likewise, for output
44 RELOAD_FOR_INSN a reload that must not conflict with anything
45 used in the insn, but may conflict with
46 something used before or after the insn
47 RELOAD_FOR_INPUT_ADDRESS reload for parts of the address of an object
48 that is an input reload
49 RELOAD_FOR_INPADDR_ADDRESS reload needed for RELOAD_FOR_INPUT_ADDRESS
50 RELOAD_FOR_OUTPUT_ADDRESS like RELOAD_FOR INPUT_ADDRESS, for output
51 RELOAD_FOR_OUTADDR_ADDRESS reload needed for RELOAD_FOR_OUTPUT_ADDRESS
52 RELOAD_FOR_OPERAND_ADDRESS reload for the address of a non-reloaded
53 operand; these don't conflict with
54 any other addresses.
55 RELOAD_FOR_OPADDR_ADDR reload needed for RELOAD_FOR_OPERAND_ADDRESS
56 reloads; usually secondary reloads
57 RELOAD_OTHER none of the above, usually multiple uses
58 RELOAD_FOR_OTHER_ADDRESS reload for part of the address of an input
59 that is marked RELOAD_OTHER.
60
61 This used to be "enum reload_when_needed" but some debuggers have trouble
62 with an enum tag and variable of the same name. */
63
64 enum reload_type
65 {
66 RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
67 RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
68 RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
69 RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
70 RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
71 };
72
73 #ifdef GCC_INSN_CODES_H
74 /* Each reload is recorded with a structure like this. */
75 struct reload
76 {
77 /* The value to reload from */
78 rtx in;
79 /* Where to store reload-reg afterward if nec (often the same as
80 reload_in) */
81 rtx out;
82
83 /* The class of registers to reload into. */
84 enum reg_class rclass;
85
86 /* The mode this operand should have when reloaded, on input. */
87 machine_mode inmode;
88 /* The mode this operand should have when reloaded, on output. */
89 machine_mode outmode;
90
91 /* The mode of the reload register. */
92 machine_mode mode;
93
94 /* the largest number of registers this reload will require. */
95 unsigned int nregs;
96
97 /* Positive amount to increment or decrement by if
98 reload_in is a PRE_DEC, PRE_INC, POST_DEC, POST_INC.
99 Ignored otherwise (don't assume it is zero). */
100 poly_int64_pod inc;
101 /* A reg for which reload_in is the equivalent.
102 If reload_in is a symbol_ref which came from
103 reg_equiv_constant, then this is the pseudo
104 which has that symbol_ref as equivalent. */
105 rtx in_reg;
106 rtx out_reg;
107
108 /* Used in find_reload_regs to record the allocated register. */
109 int regno;
110 /* This is the register to reload into. If it is zero when `find_reloads'
111 returns, you must find a suitable register in the class specified by
112 reload_reg_class, and store here an rtx for that register with mode from
113 reload_inmode or reload_outmode. */
114 rtx reg_rtx;
115 /* The operand number being reloaded. This is used to group related reloads
116 and need not always be equal to the actual operand number in the insn,
117 though it current will be; for in-out operands, it is one of the two
118 operand numbers. */
119 int opnum;
120
121 /* Gives the reload number of a secondary input reload, when needed;
122 otherwise -1. */
123 int secondary_in_reload;
124 /* Gives the reload number of a secondary output reload, when needed;
125 otherwise -1. */
126 int secondary_out_reload;
127 /* If a secondary input reload is required, gives the INSN_CODE that uses the
128 secondary reload as a scratch register, or CODE_FOR_nothing if the
129 secondary reload register is to be an intermediate register. */
130 enum insn_code secondary_in_icode;
131 /* Likewise, for a secondary output reload. */
132 enum insn_code secondary_out_icode;
133
134 /* Classifies reload as needed either for addressing an input reload,
135 addressing an output, for addressing a non-reloaded mem ref, or for
136 unspecified purposes (i.e., more than one of the above). */
137 enum reload_type when_needed;
138
139 /* Nonzero for an optional reload. Optional reloads are ignored unless the
140 value is already sitting in a register. */
141 unsigned int optional:1;
142 /* nonzero if this reload shouldn't be combined with another reload. */
143 unsigned int nocombine:1;
144 /* Nonzero if this is a secondary register for one or more reloads. */
145 unsigned int secondary_p:1;
146 /* Nonzero if this reload must use a register not already allocated to a
147 group. */
148 unsigned int nongroup:1;
149 };
150
151 extern struct reload rld[MAX_RELOADS];
152 extern int n_reloads;
153 #endif
154
155 /* Target-dependent globals. */
156 struct target_reload {
157 /* Nonzero if indirect addressing is supported when the innermost MEM is
158 of the form (MEM (SYMBOL_REF sym)). It is assumed that the level to
159 which these are valid is the same as spill_indirect_levels, above. */
160 bool x_indirect_symref_ok;
161
162 /* Nonzero if indirect addressing is supported on the machine; this means
163 that spilling (REG n) does not require reloading it into a register in
164 order to do (MEM (REG n)) or (MEM (PLUS (REG n) (CONST_INT c))). The
165 value indicates the level of indirect addressing supported, e.g., two
166 means that (MEM (MEM (REG n))) is also valid if (REG n) does not get
167 a hard register. */
168 unsigned char x_spill_indirect_levels;
169
170 /* True if caller-save has been reinitialized. */
171 bool x_caller_save_initialized_p;
172
173 /* Modes for each hard register that we can save. The smallest mode is wide
174 enough to save the entire contents of the register. When saving the
175 register because it is live we first try to save in multi-register modes.
176 If that is not possible the save is done one register at a time. */
177 machine_mode (x_regno_save_mode
178 [FIRST_PSEUDO_REGISTER]
179 [MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]);
180
181 /* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid
182 in the given mode. */
183 bool x_double_reg_address_ok[MAX_MACHINE_MODE];
184
185 /* We will only make a register eligible for caller-save if it can be
186 saved in its widest mode with a simple SET insn as long as the memory
187 address is valid. We record the INSN_CODE is those insns here since
188 when we emit them, the addresses might not be valid, so they might not
189 be recognized. */
190 int x_cached_reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
191 int x_cached_reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];
192 };
193
194 extern struct target_reload default_target_reload;
195 #if SWITCHABLE_TARGET
196 extern struct target_reload *this_target_reload;
197 #else
198 #define this_target_reload (&default_target_reload)
199 #endif
200
201 #define indirect_symref_ok \
202 (this_target_reload->x_indirect_symref_ok)
203 #define double_reg_address_ok \
204 (this_target_reload->x_double_reg_address_ok)
205 #define caller_save_initialized_p \
206 (this_target_reload->x_caller_save_initialized_p)
207
208 /* Register equivalences. Indexed by register number. */
209 struct reg_equivs_t
210 {
211 /* The constant value to which pseudo reg N is equivalent,
212 or zero if pseudo reg N is not equivalent to a constant.
213 find_reloads looks at this in order to replace pseudo reg N
214 with the constant it stands for. */
215 rtx constant;
216
217 /* An invariant value to which pseudo reg N is equivalent.
218 eliminate_regs_in_insn uses this to replace pseudos in particular
219 contexts. */
220 rtx invariant;
221
222 /* A memory location to which pseudo reg N is equivalent,
223 prior to any register elimination (such as frame pointer to stack
224 pointer). Depending on whether or not it is a valid address, this value
225 is transferred to either equiv_address or equiv_mem. */
226 rtx memory_loc;
227
228 /* The address of stack slot to which pseudo reg N is equivalent.
229 This is used when the address is not valid as a memory address
230 (because its displacement is too big for the machine.) */
231 rtx address;
232
233 /* The memory slot to which pseudo reg N is equivalent,
234 or zero if pseudo reg N is not equivalent to a memory slot. */
235 rtx mem;
236
237 /* An EXPR_LIST of REG_EQUIVs containing MEMs with
238 alternate representations of the location of pseudo reg N. */
239 rtx_expr_list *alt_mem_list;
240
241 /* The list of insns that initialized reg N from its equivalent
242 constant or memory slot. */
243 rtx_insn_list *init;
244 };
245
246 #define reg_equiv_constant(ELT) \
247 (*reg_equivs)[(ELT)].constant
248 #define reg_equiv_invariant(ELT) \
249 (*reg_equivs)[(ELT)].invariant
250 #define reg_equiv_memory_loc(ELT) \
251 (*reg_equivs)[(ELT)].memory_loc
252 #define reg_equiv_address(ELT) \
253 (*reg_equivs)[(ELT)].address
254 #define reg_equiv_mem(ELT) \
255 (*reg_equivs)[(ELT)].mem
256 #define reg_equiv_alt_mem_list(ELT) \
257 (*reg_equivs)[(ELT)].alt_mem_list
258 #define reg_equiv_init(ELT) \
259 (*reg_equivs)[(ELT)].init
260
261 extern vec<reg_equivs_t, va_gc> *reg_equivs;
262
263 /* All the "earlyclobber" operands of the current insn
264 are recorded here. */
265 extern int n_earlyclobbers;
266 extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
267
268 /* Save the number of operands. */
269 extern int reload_n_operands;
270
271 /* First uid used by insns created by reload in this function.
272 Used in find_equiv_reg. */
273 extern int reload_first_uid;
274
275 extern int num_not_at_initial_offset;
276
277 #if defined HARD_CONST && defined CLEAR_REG_SET
278 /* This structure describes instructions which are relevant for reload.
279 Apart from all regular insns, this also includes CODE_LABELs, since they
280 must be examined for register elimination. */
281 class insn_chain
282 {
283 public:
284 /* Links to the neighbor instructions. */
285 class insn_chain *next, *prev;
286
287 /* Link through a chains set up by calculate_needs_all_insns, containing
288 all insns that need reloading. */
289 class insn_chain *next_need_reload;
290
291 /* The rtx of the insn. */
292 rtx_insn *insn;
293
294 /* The basic block this insn is in. */
295 int block;
296
297 /* Nonzero if find_reloads said the insn requires reloading. */
298 unsigned int need_reload:1;
299 /* Nonzero if find_reloads needs to be run during reload_as_needed to
300 perform modifications on any operands. */
301 unsigned int need_operand_change:1;
302 /* Nonzero if eliminate_regs_in_insn said it requires eliminations. */
303 unsigned int need_elim:1;
304 /* Nonzero if this insn was inserted by perform_caller_saves. */
305 unsigned int is_caller_save_insn:1;
306
307 /* Register life information: record all live hard registers, and
308 all live pseudos that have a hard register. This set also
309 contains pseudos spilled by IRA. */
310 bitmap_head live_throughout;
311 bitmap_head dead_or_set;
312
313 /* Copies of the global variables computed by find_reloads. */
314 struct reload *rld;
315 int n_reloads;
316
317 /* Indicates which registers have already been used for spills. */
318 HARD_REG_SET used_spill_regs;
319 };
320
321 /* A chain of insn_chain structures to describe all non-note insns in
322 a function. */
323 extern class insn_chain *reload_insn_chain;
324
325 /* Allocate a new insn_chain structure. */
326 extern class insn_chain *new_insn_chain (void);
327 #endif
328
329 #if defined HARD_CONST
330 extern void compute_use_by_pseudos (HARD_REG_SET *, bitmap);
331 #endif
332
333 /* Functions from reload.cc: */
334
335 extern reg_class_t secondary_reload_class (bool, reg_class_t,
336 machine_mode, rtx);
337
338 #ifdef GCC_INSN_CODES_H
339 extern enum reg_class scratch_reload_class (enum insn_code);
340 #endif
341
342 /* Return a memory location that will be used to copy X in mode MODE.
343 If we haven't already made a location for this mode in this insn,
344 call find_reloads_address on the location being returned. */
345 extern rtx get_secondary_mem (rtx, machine_mode, int, enum reload_type);
346
347 /* Clear any secondary memory locations we've made. */
348 extern void clear_secondary_mem (void);
349
350 /* Transfer all replacements that used to be in reload FROM to be in
351 reload TO. */
352 extern void transfer_replacements (int, int);
353
354 /* IN_RTX is the value loaded by a reload that we now decided to inherit,
355 or a subpart of it. If we have any replacements registered for IN_RTX,
356 cancel the reloads that were supposed to load them.
357 Return nonzero if we canceled any reloads. */
358 extern int remove_address_replacements (rtx in_rtx);
359
360 /* Like rtx_equal_p except that it allows a REG and a SUBREG to match
361 if they are the same hard reg, and has special hacks for
362 autoincrement and autodecrement. */
363 extern int operands_match_p (rtx, rtx);
364
365 /* Return 1 if altering OP will not modify the value of CLOBBER. */
366 extern int safe_from_earlyclobber (rtx, rtx);
367
368 /* Search the body of INSN for values that need reloading and record them
369 with push_reload. REPLACE nonzero means record also where the values occur
370 so that subst_reloads can be used. */
371 extern int find_reloads (rtx_insn *, int, int, int, short *);
372
373 /* Compute the sum of X and Y, making canonicalizations assumed in an
374 address, namely: sum constant integers, surround the sum of two
375 constants with a CONST, put the constant as the second operand, and
376 group the constant on the outermost sum. */
377 extern rtx form_sum (machine_mode, rtx, rtx);
378
379 /* Substitute into the current INSN the registers into which we have reloaded
380 the things that need reloading. */
381 extern void subst_reloads (rtx_insn *);
382
383 /* Make a copy of any replacements being done into X and move those copies
384 to locations in Y, a copy of X. We only look at the highest level of
385 the RTL. */
386 extern void copy_replacements (rtx, rtx);
387
388 /* Change any replacements being done to *X to be done to *Y */
389 extern void move_replacements (rtx *x, rtx *y);
390
391 /* If LOC was scheduled to be replaced by something, return the replacement.
392 Otherwise, return *LOC. */
393 extern rtx find_replacement (rtx *);
394
395 /* Nonzero if modifying X will affect IN. */
396 extern int reg_overlap_mentioned_for_reload_p (rtx, rtx);
397
398 /* Check the insns before INSN to see if there is a suitable register
399 containing the same value as GOAL. */
400 extern rtx find_equiv_reg (rtx, rtx_insn *, enum reg_class, int, short *,
401 int, machine_mode);
402
403 /* Return 1 if register REGNO is the subject of a clobber in insn INSN. */
404 extern int regno_clobbered_p (unsigned int, rtx_insn *, machine_mode, int);
405
406 /* Return 1 if X is an operand of an insn that is being earlyclobbered. */
407 extern int earlyclobber_operand_p (rtx);
408
409 /* Record one reload that needs to be performed. */
410 extern int push_reload (rtx, rtx, rtx *, rtx *, enum reg_class,
411 machine_mode, machine_mode,
412 int, int, int, enum reload_type);
413
414 /* Functions in reload1.cc: */
415
416 /* Initialize the reload pass once per compilation. */
417 extern void init_reload (void);
418
419 /* The reload pass itself. */
420 extern bool reload (rtx_insn *, int);
421
422 /* Mark the slots in regs_ever_live for the hard regs
423 used by pseudo-reg number REGNO. */
424 extern void mark_home_live (int);
425
426 /* Scan X and replace any eliminable registers (such as fp) with a
427 replacement (such as sp), plus an offset. */
428 extern rtx eliminate_regs (rtx, machine_mode, rtx);
429 extern bool elimination_target_reg_p (rtx);
430
431 /* Called from the register allocator to estimate costs of eliminating
432 invariant registers. */
433 extern void calculate_elim_costs_all_insns (void);
434
435 /* Deallocate the reload register used by reload number R. */
436 extern void deallocate_reload_reg (int r);
437
438 /* Functions in caller-save.cc: */
439
440 /* Initialize for caller-save. */
441 extern void init_caller_save (void);
442
443 /* Initialize save areas by showing that we haven't allocated any yet. */
444 extern void init_save_areas (void);
445
446 /* Allocate save areas for any hard registers that might need saving. */
447 extern void setup_save_areas (void);
448
449 /* Find the places where hard regs are live across calls and save them. */
450 extern void save_call_clobbered_regs (void);
451
452 /* Replace (subreg (reg)) with the appropriate (reg) for any operands. */
453 extern void cleanup_subreg_operands (rtx_insn *);
454
455 /* Debugging support. */
456 extern void debug_reload_to_stream (FILE *);
457 extern void debug_reload (void);
458
459 /* Compute the actual register we should reload to, in case we're
460 reloading to/from a register that is wider than a word. */
461 extern rtx reload_adjust_reg_for_mode (rtx, machine_mode);
462
463 /* Allocate or grow the reg_equiv tables, initializing new entries to 0. */
464 extern void grow_reg_equivs (void);
465
466 #endif /* GCC_RELOAD_H */