1/* Communication between reload.c and reload1.c.
2   Copyright (C) 1987, 1991, 1992, 1993, 1994, 1995, 1997, 1998, 2000
3   Free Software Foundation, Inc.
4
5This file is part of GNU CC.
6
7GNU CC is free software; you can redistribute it and/or modify
8it under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 2, or (at your option)
10any later version.
11
12GNU CC is distributed in the hope that it will be useful,
13but WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15GNU General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along with GNU CC; see the file COPYING.  If not, write to
19the Free Software Foundation, 59 Temple Place - Suite 330,
20Boston, MA 02111-1307, USA.  */
21
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/* If either macro is defined, show that we need secondary reloads.  */
34#if defined(SECONDARY_INPUT_RELOAD_CLASS) || defined(SECONDARY_OUTPUT_RELOAD_CLASS)
35#define HAVE_SECONDARY_RELOADS
36#endif
37
38/* If MEMORY_MOVE_COST isn't defined, give it a default here.  */
39#ifndef MEMORY_MOVE_COST
40#ifdef HAVE_SECONDARY_RELOADS
41#define MEMORY_MOVE_COST(MODE,CLASS,IN) \
42  (4 + memory_move_secondary_cost ((MODE), (CLASS), (IN)))
43#else
44#define MEMORY_MOVE_COST(MODE,CLASS,IN) 4
45#endif
46#endif
47extern int memory_move_secondary_cost PROTO ((enum machine_mode, enum reg_class, int));
48
49/* See reload.c and reload1.c for comments on these variables.  */
50
51/* Maximum number of reloads we can need.  */
52#define MAX_RELOADS (2 * MAX_RECOG_OPERANDS * (MAX_REGS_PER_ADDRESS + 1))
53
54extern rtx reload_in[MAX_RELOADS];
55extern rtx reload_out[MAX_RELOADS];
56extern rtx reload_in_reg[MAX_RELOADS];
57extern rtx reload_out_reg[MAX_RELOADS];
58extern enum reg_class reload_reg_class[MAX_RELOADS];
59extern enum machine_mode reload_inmode[MAX_RELOADS];
60extern enum machine_mode reload_outmode[MAX_RELOADS];
61extern char reload_optional[MAX_RELOADS];
62extern char reload_nongroup[MAX_RELOADS];
63extern int reload_inc[MAX_RELOADS];
64extern int reload_opnum[MAX_RELOADS];
65extern int reload_secondary_p[MAX_RELOADS];
66extern int reload_secondary_in_reload[MAX_RELOADS];
67extern int reload_secondary_out_reload[MAX_RELOADS];
68#ifdef MAX_INSN_CODE
69extern enum insn_code reload_secondary_in_icode[MAX_RELOADS];
70extern enum insn_code reload_secondary_out_icode[MAX_RELOADS];
71#endif
72extern int n_reloads;
73
74extern rtx reload_reg_rtx[MAX_RELOADS];
75
76/* Encode the usage of a reload.  The following codes are supported:
77
78   RELOAD_FOR_INPUT		reload of an input operand
79   RELOAD_FOR_OUTPUT		likewise, for output
80   RELOAD_FOR_INSN		a reload that must not conflict with anything
81				used in the insn, but may conflict with
82				something used before or after the insn
83   RELOAD_FOR_INPUT_ADDRESS	reload for parts of the address of an object
84				that is an input reload
85   RELOAD_FOR_INPADDR_ADDRESS	reload needed for RELOAD_FOR_INPUT_ADDRESS
86   RELOAD_FOR_OUTPUT_ADDRESS	like RELOAD_FOR INPUT_ADDRESS, for output
87   RELOAD_FOR_OUTADDR_ADDRESS	reload needed for RELOAD_FOR_OUTPUT_ADDRESS
88   RELOAD_FOR_OPERAND_ADDRESS	reload for the address of a non-reloaded
89				operand; these don't conflict with
90				any other addresses.
91   RELOAD_FOR_OPADDR_ADDR	reload needed for RELOAD_FOR_OPERAND_ADDRESS
92                                reloads; usually secondary reloads
93   RELOAD_OTHER			none of the above, usually multiple uses
94   RELOAD_FOR_OTHER_ADDRESS     reload for part of the address of an input
95   				that is marked RELOAD_OTHER.
96
97   This used to be "enum reload_when_needed" but some debuggers have trouble
98   with an enum tag and variable of the same name.  */
99
100enum reload_type
101{
102  RELOAD_FOR_INPUT, RELOAD_FOR_OUTPUT, RELOAD_FOR_INSN,
103  RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_INPADDR_ADDRESS,
104  RELOAD_FOR_OUTPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS,
105  RELOAD_FOR_OPERAND_ADDRESS, RELOAD_FOR_OPADDR_ADDR,
106  RELOAD_OTHER, RELOAD_FOR_OTHER_ADDRESS
107};
108
109extern enum reload_type reload_when_needed[MAX_RELOADS];
110
111extern rtx *reg_equiv_constant;
112extern rtx *reg_equiv_memory_loc;
113extern rtx *reg_equiv_address;
114extern rtx *reg_equiv_mem;
115
116/* All the "earlyclobber" operands of the current insn
117   are recorded here.  */
118extern int n_earlyclobbers;
119extern rtx reload_earlyclobbers[MAX_RECOG_OPERANDS];
120
121/* Save the number of operands.  */
122extern int reload_n_operands;
123
124/* First uid used by insns created by reload in this function.
125   Used in find_equiv_reg.  */
126extern int reload_first_uid;
127
128/* Nonzero if indirect addressing is supported when the innermost MEM is
129   of the form (MEM (SYMBOL_REF sym)).  It is assumed that the level to
130   which these are valid is the same as spill_indirect_levels, above.   */
131
132extern char indirect_symref_ok;
133
134/* Nonzero if an address (plus (reg frame_pointer) (reg ...)) is valid.  */
135extern char double_reg_address_ok;
136
137extern int num_not_at_initial_offset;
138
139#ifdef MAX_INSN_CODE
140/* These arrays record the insn_code of insns that may be needed to
141   perform input and output reloads of special objects.  They provide a
142   place to pass a scratch register.  */
143extern enum insn_code reload_in_optab[];
144extern enum insn_code reload_out_optab[];
145#endif
146
147struct needs
148{
149  /* [0] is normal, [1] is nongroup.  */
150  short regs[2][N_REG_CLASSES];
151  short groups[N_REG_CLASSES];
152};
153
154#if defined SET_HARD_REG_BIT && defined CLEAR_REG_SET
155/* This structure describes instructions which are relevant for reload.
156   Apart from all regular insns, this also includes CODE_LABELs, since they
157   must be examined for register elimination.  */
158struct insn_chain
159{
160  /* Links to the neighbour instructions.  */
161  struct insn_chain *next, *prev;
162
163  /* Link through a chains set up by calculate_needs_all_insns, containing
164     all insns that need reloading.  */
165  struct insn_chain *next_need_reload;
166
167  /* The basic block this insn is in.  */
168  int block;
169  /* The rtx of the insn.  */
170  rtx insn;
171  /* Register life information: record all live hard registers, and all
172     live pseudos that have a hard register.
173     This information is recorded for the point immediately before the insn
174     (in live_before), and for the point within the insn at which all
175     outputs have just been written to (in live_after).  */
176  regset live_before;
177  regset live_after;
178
179  /* For each class, size of group of consecutive regs
180     that is needed for the reloads of this class.  */
181  char group_size[N_REG_CLASSES];
182  /* For each class, the machine mode which requires consecutive
183     groups of regs of that class.
184     If two different modes ever require groups of one class,
185     they must be the same size and equally restrictive for that class,
186     otherwise we can't handle the complexity.  */
187  enum machine_mode group_mode[N_REG_CLASSES];
188
189  /* Indicates if a register was counted against the need for
190     groups.  0 means it can count against max_nongroup instead.  */
191  HARD_REG_SET counted_for_groups;
192
193  /* Indicates if a register was counted against the need for
194     non-groups.  0 means it can become part of a new group.
195     During choose_reload_regs, 1 here means don't use this reg
196     as part of a group, even if it seems to be otherwise ok.  */
197  HARD_REG_SET counted_for_nongroups;
198
199  /* Indicates which registers have already been used for spills.  */
200  HARD_REG_SET used_spill_regs;
201
202  /* Describe the needs for reload registers of this insn.  */
203  struct needs need;
204
205  /* Nonzero if find_reloads said the insn requires reloading.  */
206  unsigned int need_reload:1;
207  /* Nonzero if find_reloads needs to be run during reload_as_needed to
208     perform modifications on any operands.  */
209  unsigned int need_operand_change:1;
210  /* Nonzero if eliminate_regs_in_insn said it requires eliminations.  */
211  unsigned int need_elim:1;
212  /* Nonzero if this insn was inserted by perform_caller_saves.  */
213  unsigned int is_caller_save_insn:1;
214};
215
216/* A chain of insn_chain structures to describe all non-note insns in
217   a function.  */
218extern struct insn_chain *reload_insn_chain;
219
220/* Allocate a new insn_chain structure.  */
221extern struct insn_chain *new_insn_chain	PROTO((void));
222
223extern void compute_use_by_pseudos		PROTO((HARD_REG_SET *, regset));
224#endif
225
226/* Functions from reload.c:  */
227
228/* Return a memory location that will be used to copy X in mode MODE.
229   If we haven't already made a location for this mode in this insn,
230   call find_reloads_address on the location being returned.  */
231extern rtx get_secondary_mem PROTO((rtx, enum machine_mode,
232				    int, enum reload_type));
233
234/* Clear any secondary memory locations we've made.  */
235extern void clear_secondary_mem PROTO((void));
236
237/* Transfer all replacements that used to be in reload FROM to be in
238   reload TO.  */
239extern void transfer_replacements PROTO((int, int));
240
241/* IN_RTX is the value loaded by a reload that we now decided to inherit,
242   or a subpart of it.  If we have any replacements registered for IN_RTX,
243   chancel the reloads that were supposed to load them.
244   Return non-zero if we chanceled any reloads.  */
245extern int remove_address_replacements PROTO((rtx in_rtx));
246
247/* Like rtx_equal_p except that it allows a REG and a SUBREG to match
248   if they are the same hard reg, and has special hacks for
249   autoincrement and autodecrement.  */
250extern int operands_match_p PROTO((rtx, rtx));
251
252/* Return 1 if altering OP will not modify the value of CLOBBER. */
253extern int safe_from_earlyclobber PROTO((rtx, rtx));
254
255/* Search the body of INSN for values that need reloading and record them
256   with push_reload.  REPLACE nonzero means record also where the values occur
257   so that subst_reloads can be used.  */
258extern int find_reloads PROTO((rtx, int, int, int, short *));
259
260/* Compute the sum of X and Y, making canonicalizations assumed in an
261   address, namely: sum constant integers, surround the sum of two
262   constants with a CONST, put the constant as the second operand, and
263   group the constant on the outermost sum.  */
264extern rtx form_sum PROTO((rtx, rtx));
265
266/* Substitute into the current INSN the registers into which we have reloaded
267   the things that need reloading.  */
268extern void subst_reloads PROTO((void));
269
270/* Make a copy of any replacements being done into X and move those copies
271   to locations in Y, a copy of X.  We only look at the highest level of
272   the RTL.  */
273extern void copy_replacements PROTO((rtx, rtx));
274
275/* Change any replacements being done to *X to be done to *Y */
276extern void move_replacements PROTO((rtx *x, rtx *y));
277
278/* If LOC was scheduled to be replaced by something, return the replacement.
279   Otherwise, return *LOC.  */
280extern rtx find_replacement PROTO((rtx *));
281
282/* Return nonzero if register in range [REGNO, ENDREGNO)
283   appears either explicitly or implicitly in X
284   other than being stored into.  */
285extern int refers_to_regno_for_reload_p PROTO((int, int, rtx, rtx *));
286
287/* Nonzero if modifying X will affect IN.  */
288extern int reg_overlap_mentioned_for_reload_p PROTO((rtx, rtx));
289
290/* Return nonzero if anything in X contains a MEM.  Look also for pseudo
291   registers.  */
292extern int refers_to_mem_for_reload_p PROTO((rtx));
293
294/* Check the insns before INSN to see if there is a suitable register
295   containing the same value as GOAL.  */
296extern rtx find_equiv_reg PROTO((rtx, rtx, enum reg_class, int, short *,
297				 int, enum machine_mode));
298
299/* Return 1 if register REGNO is the subject of a clobber in insn INSN.  */
300extern int regno_clobbered_p PROTO((int, rtx, enum machine_mode, int));
301
302/* Functions in reload1.c:  */
303
304extern int reloads_conflict		PROTO ((int, int));
305
306int count_occurrences            PROTO((rtx, rtx));
307
308/* Initialize the reload pass once per compilation.  */
309extern void init_reload PROTO((void));
310
311/* The reload pass itself.  */
312extern int reload PROTO((rtx, int, FILE *));
313
314/* Mark the slots in regs_ever_live for the hard regs
315   used by pseudo-reg number REGNO.  */
316extern void mark_home_live PROTO((int));
317
318/* Scan X and replace any eliminable registers (such as fp) with a
319   replacement (such as sp), plus an offset.  */
320extern rtx eliminate_regs PROTO((rtx, enum machine_mode, rtx));
321
322/* Emit code to perform a reload from IN (which may be a reload register) to
323   OUT (which may also be a reload register).  IN or OUT is from operand
324   OPNUM with reload type TYPE.  */
325extern rtx gen_reload PROTO((rtx, rtx, int, enum reload_type));
326
327/* Deallocate the reload register used by reload number R.  */
328extern void deallocate_reload_reg PROTO((int r));
329
330/* Functions in caller-save.c:  */
331
332/* Initialize for caller-save.  */
333extern void init_caller_save PROTO((void));
334
335/* Initialize save areas by showing that we haven't allocated any yet.  */
336extern void init_save_areas PROTO((void));
337
338/* Allocate save areas for any hard registers that might need saving.  */
339extern void setup_save_areas PROTO((void));
340
341/* Find the places where hard regs are live across calls and save them.  */
342extern void save_call_clobbered_regs PROTO((void));
343
344/* Replace (subreg (reg)) with the appropriate (reg) for any operands.  */
345extern void cleanup_subreg_operands PROTO ((rtx));
346
347extern int earlyclobber_operand_p PROTO((rtx));
348