GCC Middle and Back End API Reference
reload.h
Go to the documentation of this file.
1/* Communication between reload.cc, reload1.cc and the rest of compiler.
2 Copyright (C) 1987-2024 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along 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
33extern int register_move_cost (machine_mode, reg_class_t, reg_class_t);
34extern int memory_move_cost (machine_mode, reg_class_t, bool);
35extern 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
72
73#ifdef GCC_INSN_CODES_H
74/* Each reload is recorded with a structure like this. */
75struct 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 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
151extern struct reload rld[MAX_RELOADS];
152extern int n_reloads;
153#endif
154
155/* Target-dependent globals. */
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. */
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. */
169
170 /* True if caller-save has been reinitialized. */
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]
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
195#if SWITCHABLE_TARGET
196extern 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. */
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. */
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. */
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. */
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.) */
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. */
236
237 /* An EXPR_LIST of REG_EQUIVs containing MEMs with
238 alternate representations of the location of pseudo reg N. */
240
241 /* The list of insns that initialized reg N from its equivalent
242 constant or memory slot. */
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
262
263/* All the "earlyclobber" operands of the current insn
264 are recorded here. */
265extern int n_earlyclobbers;
266extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
267
268/* Save the number of operands. */
269extern int reload_n_operands;
270
271/* First uid used by insns created by reload in this function.
272 Used in find_equiv_reg. */
273extern int reload_first_uid;
274
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. */
281class insn_chain
282{
283public:
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. */
319};
320
321/* A chain of insn_chain structures to describe all non-note insns in
322 a function. */
323extern class insn_chain *reload_insn_chain;
324
325/* Allocate a new insn_chain structure. */
326extern class insn_chain *new_insn_chain (void);
327#endif
328
329#if defined HARD_CONST
331#endif
332
333/* Functions from reload.cc: */
334
336 machine_mode, rtx);
337
338#ifdef GCC_INSN_CODES_H
339extern 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. */
345extern rtx get_secondary_mem (rtx, machine_mode, int, enum reload_type);
346
347/* Clear any secondary memory locations we've made. */
348extern void clear_secondary_mem (void);
349
350/* Transfer all replacements that used to be in reload FROM to be in
351 reload TO. */
352extern 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. */
358extern 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. */
363extern int operands_match_p (rtx, rtx);
364
365/* Return 1 if altering OP will not modify the value of CLOBBER. */
366extern 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. */
371extern 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. */
377extern 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. */
381extern 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. */
386extern void copy_replacements (rtx, rtx);
387
388/* Change any replacements being done to *X to be done to *Y */
389extern 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. */
393extern rtx find_replacement (rtx *);
394
395/* Nonzero if modifying X will affect IN. */
397
398/* Check the insns before INSN to see if there is a suitable register
399 containing the same value as GOAL. */
400extern 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. */
404extern 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. */
407extern int earlyclobber_operand_p (rtx);
408
409/* Record one reload that needs to be performed. */
410extern 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. */
417extern void init_reload (void);
418
419/* The reload pass itself. */
420extern 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. */
424extern 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. */
428extern rtx eliminate_regs (rtx, machine_mode, rtx);
429extern bool elimination_target_reg_p (rtx);
430
431/* Called from the register allocator to estimate costs of eliminating
432 invariant registers. */
433extern void calculate_elim_costs_all_insns (void);
434
435/* Deallocate the reload register used by reload number R. */
436extern void deallocate_reload_reg (int r);
437
438/* Functions in caller-save.cc: */
439
440/* Initialize for caller-save. */
441extern void init_caller_save (void);
442
443/* Initialize save areas by showing that we haven't allocated any yet. */
444extern void init_save_areas (void);
445
446/* Allocate save areas for any hard registers that might need saving. */
447extern void setup_save_areas (void);
448
449/* Find the places where hard regs are live across calls and save them. */
450extern void save_call_clobbered_regs (void);
451
452/* Replace (subreg (reg)) with the appropriate (reg) for any operands. */
453extern void cleanup_subreg_operands (rtx_insn *);
454
455/* Debugging support. */
456extern void debug_reload_to_stream (FILE *);
457extern 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. */
461extern rtx reload_adjust_reg_for_mode (rtx, machine_mode);
462
463/* Allocate or grow the reg_equiv tables, initializing new entries to 0. */
464extern void grow_reg_equivs (void);
465
466#endif /* GCC_RELOAD_H */
Definition bitmap.h:328
int reg_class_t
Definition coretypes.h:376
class bitmap_head * bitmap
Definition coretypes.h:51
#define MAX_MOVE_MAX
Definition defaults.h:999
#define MIN_UNITS_PER_WORD
Definition defaults.h:1003
HARD_REG_ELT_TYPE HARD_REG_SET
Definition hard-reg-set.h:47
poly_int< N, C > r
Definition poly-int.h:774
void compute_use_by_pseudos(HARD_REG_SET *to, regset from)
Definition reload1.cc:501
static HARD_REG_SET used_spill_regs
Definition reload1.cc:189
class insn_chain * reload_insn_chain
Definition reload1.cc:242
class insn_chain * new_insn_chain(void)
Definition reload1.cc:475
int n_reloads
Definition reload.cc:132
enum reg_class scratch_reload_class(enum insn_code icode)
Definition reload.cc:536
struct reload rld[MAX_RELOADS]
Definition reload.cc:133
reload_type
Definition reload.h:65
@ RELOAD_OTHER
Definition reload.h:70
@ RELOAD_FOR_INPADDR_ADDRESS
Definition reload.h:67
@ RELOAD_FOR_OUTADDR_ADDRESS
Definition reload.h:68
@ RELOAD_FOR_INSN
Definition reload.h:66
@ RELOAD_FOR_OUTPUT_ADDRESS
Definition reload.h:68
@ RELOAD_FOR_OUTPUT
Definition reload.h:66
@ RELOAD_FOR_INPUT_ADDRESS
Definition reload.h:67
@ RELOAD_FOR_OPERAND_ADDRESS
Definition reload.h:69
@ RELOAD_FOR_OPADDR_ADDR
Definition reload.h:69
@ RELOAD_FOR_INPUT
Definition reload.h:66
@ RELOAD_FOR_OTHER_ADDRESS
Definition reload.h:70
rtx eliminate_regs(rtx, machine_mode, rtx)
Definition reload1.cc:2940
void grow_reg_equivs(void)
Definition reload1.cc:644
void transfer_replacements(int, int)
Definition reload.cc:1675
void cleanup_subreg_operands(rtx_insn *)
Definition final.cc:3049
int remove_address_replacements(rtx in_rtx)
Definition reload.cc:1689
int reload_n_operands
Definition reload.cc:140
bool elimination_target_reg_p(rtx)
Definition reload1.cc:3949
int memory_move_cost(machine_mode, reg_class_t, bool)
Definition reginfo.cc:553
vec< reg_equivs_t, va_gc > * reg_equivs
Definition reload1.cc:320
int regno_clobbered_p(unsigned int, rtx_insn *, machine_mode, int)
Definition reload.cc:7194
int find_reloads(rtx_insn *, int, int, int, short *)
Definition reload.cc:2609
void save_call_clobbered_regs(void)
Definition caller-save.cc:728
rtx form_sum(machine_mode, rtx, rtx)
Definition reload.cc:5353
void move_replacements(rtx *x, rtx *y)
Definition reload.cc:6365
void calculate_elim_costs_all_insns(void)
Definition reload1.cc:1555
void init_save_areas(void)
Definition caller-save.cc:276
int register_move_cost(machine_mode, reg_class_t, reg_class_t)
Definition reginfo.cc:545
int reload_first_uid
Definition reload1.cc:213
void init_reload(void)
Definition reload1.cc:414
int operands_match_p(rtx, rtx)
Definition reload.cc:2196
bool reload(rtx_insn *, int)
Definition reload1.cc:750
int num_not_at_initial_offset
Definition reload1.cc:299
void deallocate_reload_reg(int r)
Definition reload1.cc:7008
rtx get_secondary_mem(rtx, machine_mode, int, enum reload_type)
Definition reload.cc:557
rtx reload_adjust_reg_for_mode(rtx, machine_mode)
Definition reload.cc:7241
struct target_reload default_target_reload
Definition reload1.cc:81
reg_class_t secondary_reload_class(bool, reg_class_t, machine_mode, rtx)
Definition reload.cc:508
int reg_overlap_mentioned_for_reload_p(rtx, rtx)
Definition reload.cc:6550
int memory_move_secondary_cost(machine_mode, reg_class_t, bool)
Definition reginfo.cc:561
void setup_save_areas(void)
Definition caller-save.cc:401
rtx find_replacement(rtx *)
Definition reload.cc:6378
rtx reload_earlyclobbers[MAX_RECOG_OPERANDS]
Definition reload.cc:138
void debug_reload(void)
Definition reload.cc:7373
#define this_target_reload
Definition reload.h:198
void subst_reloads(rtx_insn *)
Definition reload.cc:6255
void init_caller_save(void)
Definition caller-save.cc:184
void copy_replacements(rtx, rtx)
Definition reload.cc:6323
void clear_secondary_mem(void)
Definition reload.cc:624
rtx find_equiv_reg(rtx, rtx_insn *, enum reg_class, int, short *, int, machine_mode)
Definition reload.cc:6677
int push_reload(rtx, rtx, rtx *, rtx *, enum reg_class, machine_mode, machine_mode, int, int, int, enum reload_type)
Definition reload.cc:952
int safe_from_earlyclobber(rtx, rtx)
Definition reload.cc:2578
#define MAX_RELOADS
Definition reload.h:38
void mark_home_live(int)
Definition reload1.cc:2309
void debug_reload_to_stream(FILE *)
Definition reload.cc:7275
int earlyclobber_operand_p(rtx)
Definition reload.cc:2112
int n_earlyclobbers
Definition reload.cc:137
Definition reload.h:210
rtx address
Definition reload.h:231
rtx memory_loc
Definition reload.h:226
rtx constant
Definition reload.h:215
rtx_insn_list * init
Definition reload.h:243
rtx invariant
Definition reload.h:220
rtx_expr_list * alt_mem_list
Definition reload.h:239
rtx mem
Definition reload.h:235
Definition rtl.h:311
Definition rtl.h:458
Definition rtl.h:479
Definition rtl.h:545
Definition reload.h:156
unsigned char x_spill_indirect_levels
Definition reload.h:168
machine_mode(x_regno_save_mode[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX/MIN_UNITS_PER_WORD+1])
bool x_indirect_symref_ok
Definition reload.h:160
bool x_caller_save_initialized_p
Definition reload.h:171
bool x_double_reg_address_ok[MAX_MACHINE_MODE]
Definition reload.h:183
int x_cached_reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE]
Definition reload.h:191
int x_cached_reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE]
Definition reload.h:190
Definition vec.h:450
const T2 & y
Definition wide-int.h:3870