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60b058ed WJ |
1 | /* Subroutines for manipulating rtx's in semantically interesting ways. |
2 | Copyright (C) 1987 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GNU CC. | |
5 | ||
6 | GNU CC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU CC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | ||
21 | #include "config.h" | |
22 | #include "rtl.h" | |
23 | #include "tree.h" | |
24 | #include "flags.h" | |
25 | #include "expr.h" | |
26 | ||
27 | /* Return an rtx for the sum of X and the integer C. */ | |
28 | ||
29 | rtx | |
30 | plus_constant (x, c) | |
31 | register rtx x; | |
32 | register int c; | |
33 | { | |
34 | register RTX_CODE code = GET_CODE (x); | |
35 | register enum machine_mode mode = GET_MODE (x); | |
36 | int all_constant = 0; | |
37 | ||
38 | if (c == 0) | |
39 | return x; | |
40 | ||
41 | if (code == CONST_INT) | |
42 | return gen_rtx (CONST_INT, VOIDmode, (INTVAL (x) + c)); | |
43 | ||
44 | /* If adding to something entirely constant, set a flag | |
45 | so that we can add a CONST around the result. */ | |
46 | if (code == CONST) | |
47 | { | |
48 | x = XEXP (x, 0); | |
49 | all_constant = 1; | |
50 | } | |
51 | else if (code == SYMBOL_REF || code == LABEL_REF) | |
52 | all_constant = 1; | |
53 | ||
54 | /* The interesting case is adding the integer to a sum. | |
55 | Look for constant term in the sum and combine | |
56 | with C. For an integer constant term, we make a combined | |
57 | integer. For a constant term that is not an explicit integer, | |
58 | we cannot really combine, but group them together anyway. */ | |
59 | ||
60 | if (GET_CODE (x) == PLUS) | |
61 | { | |
62 | if (GET_CODE (XEXP (x, 0)) == CONST_INT) | |
63 | { | |
64 | c += INTVAL (XEXP (x, 0)); | |
65 | x = XEXP (x, 1); | |
66 | } | |
67 | else if (GET_CODE (XEXP (x, 1)) == CONST_INT) | |
68 | { | |
69 | c += INTVAL (XEXP (x, 1)); | |
70 | x = XEXP (x, 0); | |
71 | } | |
72 | else if (CONSTANT_P (XEXP (x, 0))) | |
73 | { | |
74 | return gen_rtx (PLUS, mode, | |
75 | plus_constant (XEXP (x, 0), c), | |
76 | XEXP (x, 1)); | |
77 | } | |
78 | else if (CONSTANT_P (XEXP (x, 1))) | |
79 | { | |
80 | return gen_rtx (PLUS, mode, | |
81 | XEXP (x, 0), | |
82 | plus_constant (XEXP (x, 1), c)); | |
83 | } | |
84 | #ifdef OLD_INDEXING | |
85 | /* Detect adding a constant to an indexed address | |
86 | of the form (PLUS (MULT (REG) (CONST)) regs-and-constants). | |
87 | Keep the (MULT ...) at the top level of addition so that | |
88 | the result is still suitable for indexing and constants | |
89 | are combined. */ | |
90 | else if (GET_CODE (XEXP (x, 0)) == MULT) | |
91 | { | |
92 | return gen_rtx (PLUS, mode, XEXP (x, 0), | |
93 | plus_constant (XEXP (x, 1), c)); | |
94 | } | |
95 | else if (GET_CODE (XEXP (x, 1)) == MULT) | |
96 | { | |
97 | return gen_rtx (PLUS, mode, plus_constant (XEXP (x, 0), c), | |
98 | XEXP (x, 1)); | |
99 | } | |
100 | #endif | |
101 | } | |
102 | if (c != 0) | |
103 | x = gen_rtx (PLUS, mode, x, gen_rtx (CONST_INT, VOIDmode, c)); | |
104 | ||
105 | if (GET_CODE (x) == SYMBOL_REF || GET_CODE (x) == LABEL_REF) | |
106 | return x; | |
107 | else if (all_constant) | |
108 | return gen_rtx (CONST, mode, x); | |
109 | else | |
110 | return x; | |
111 | } | |
112 | \f | |
113 | /* If X is a sum, return a new sum like X but lacking any constant terms. | |
114 | Add all the removed constant terms into *CONSTPTR. | |
115 | X itself is not altered. The result != X if and only if | |
116 | it is not isomorphic to X. */ | |
117 | ||
118 | rtx | |
119 | eliminate_constant_term (x, constptr) | |
120 | rtx x; | |
121 | int *constptr; | |
122 | { | |
123 | int c; | |
124 | register rtx x0, x1; | |
125 | ||
126 | if (GET_CODE (x) != PLUS) | |
127 | return x; | |
128 | ||
129 | /* First handle constants appearing at this level explicitly. */ | |
130 | if (GET_CODE (XEXP (x, 0)) == CONST_INT) | |
131 | { | |
132 | *constptr += INTVAL (XEXP (x, 0)); | |
133 | return eliminate_constant_term (XEXP (x, 1), constptr); | |
134 | } | |
135 | ||
136 | if (GET_CODE (XEXP (x, 1)) == CONST_INT) | |
137 | { | |
138 | *constptr += INTVAL (XEXP (x, 1)); | |
139 | return eliminate_constant_term (XEXP (x, 0), constptr); | |
140 | } | |
141 | ||
142 | c = 0; | |
143 | x0 = eliminate_constant_term (XEXP (x, 0), &c); | |
144 | x1 = eliminate_constant_term (XEXP (x, 1), &c); | |
145 | if (x1 != XEXP (x, 1) || x0 != XEXP (x, 0)) | |
146 | { | |
147 | *constptr += c; | |
148 | return gen_rtx (PLUS, GET_MODE (x), x0, x1); | |
149 | } | |
150 | return x; | |
151 | } | |
152 | ||
153 | /* Return an rtx for the size in bytes of the value of EXP. */ | |
154 | ||
155 | rtx | |
156 | expr_size (exp) | |
157 | tree exp; | |
158 | { | |
159 | return expand_expr (size_in_bytes (TREE_TYPE (exp)), 0, SImode, 0); | |
160 | } | |
161 | ||
162 | /* Not yet really written since C does not need it. */ | |
163 | ||
164 | rtx | |
165 | lookup_static_chain (context) | |
166 | rtx context; | |
167 | { | |
168 | abort (); | |
169 | } | |
170 | \f | |
171 | /* Return a copy of X in which all memory references | |
172 | and all constants that involve symbol refs | |
173 | have been replaced with new temporary registers. | |
174 | Also emit code to load the memory locations and constants | |
175 | into those registers. | |
176 | ||
177 | If X contains no such constants or memory references, | |
178 | X itself (not a copy) is returned. | |
179 | ||
180 | X may contain no arithmetic except addition, subtraction and multiplication. | |
181 | Values returned by expand_expr with 1 for sum_ok fit this constraint. */ | |
182 | ||
183 | static rtx | |
184 | break_out_memory_refs (x) | |
185 | register rtx x; | |
186 | { | |
187 | if (GET_CODE (x) == MEM || GET_CODE (x) == CONST | |
188 | || GET_CODE (x) == SYMBOL_REF) | |
189 | { | |
190 | register rtx temp = force_reg (Pmode, x); | |
191 | mark_reg_pointer (temp); | |
192 | x = temp; | |
193 | } | |
194 | else if (GET_CODE (x) == PLUS || GET_CODE (x) == MINUS | |
195 | || GET_CODE (x) == MULT) | |
196 | { | |
197 | register rtx op0 = break_out_memory_refs (XEXP (x, 0)); | |
198 | register rtx op1 = break_out_memory_refs (XEXP (x, 1)); | |
199 | if (op0 != XEXP (x, 0) || op1 != XEXP (x, 1)) | |
200 | x = gen_rtx (GET_CODE (x), Pmode, op0, op1); | |
201 | } | |
202 | return x; | |
203 | } | |
204 | ||
205 | /* Given a memory address or facsimile X, construct a new address, | |
206 | currently equivalent, that is stable: future stores won't change it. | |
207 | ||
208 | X must be composed of constants, register and memory references | |
209 | combined with addition, subtraction and multiplication: | |
210 | in other words, just what you can get from expand_expr if sum_ok is 1. | |
211 | ||
212 | Works by making copies of all regs and memory locations used | |
213 | by X and combining them the same way X does. | |
214 | You could also stabilize the reference to this address | |
215 | by copying the address to a register with copy_to_reg; | |
216 | but then you wouldn't get indexed addressing in the reference. */ | |
217 | ||
218 | rtx | |
219 | copy_all_regs (x) | |
220 | register rtx x; | |
221 | { | |
222 | if (GET_CODE (x) == REG) | |
223 | { | |
224 | if (REGNO (x) != FRAME_POINTER_REGNUM) | |
225 | x = copy_to_reg (x); | |
226 | } | |
227 | else if (GET_CODE (x) == MEM) | |
228 | x = copy_to_reg (x); | |
229 | else if (GET_CODE (x) == PLUS || GET_CODE (x) == MINUS | |
230 | || GET_CODE (x) == MULT) | |
231 | { | |
232 | register rtx op0 = copy_all_regs (XEXP (x, 0)); | |
233 | register rtx op1 = copy_all_regs (XEXP (x, 1)); | |
234 | if (op0 != XEXP (x, 0) || op1 != XEXP (x, 1)) | |
235 | x = gen_rtx (GET_CODE (x), Pmode, op0, op1); | |
236 | } | |
237 | return x; | |
238 | } | |
239 | \f | |
240 | /* Return something equivalent to X but valid as a memory address | |
241 | for something of mode MODE. When X is not itself valid, this | |
242 | works by copying X or subexpressions of it into registers. */ | |
243 | ||
244 | rtx | |
245 | memory_address (mode, x) | |
246 | enum machine_mode mode; | |
247 | register rtx x; | |
248 | { | |
249 | register rtx oldx; | |
250 | ||
251 | /* By passing constant addresses thru registers | |
252 | we get a chance to cse them. */ | |
253 | if (! cse_not_expected && CONSTANT_P (x)) | |
254 | return force_reg (Pmode, x); | |
255 | ||
256 | /* Accept a QUEUED that refers to a REG | |
257 | even though that isn't a valid address. | |
258 | On attempting to put this in an insn we will call protect_from_queue | |
259 | which will turn it into a REG, which is valid. */ | |
260 | if (GET_CODE (x) == QUEUED | |
261 | && GET_CODE (QUEUED_VAR (x)) == REG) | |
262 | return x; | |
263 | ||
264 | /* We get better cse by rejecting indirect addressing at this stage. | |
265 | Let the combiner create indirect addresses where appropriate. | |
266 | For now, generate the code so that the subexpressions useful to share | |
267 | are visible. But not if cse won't be done! */ | |
268 | oldx = x; | |
269 | if (! cse_not_expected && GET_CODE (x) != REG) | |
270 | x = break_out_memory_refs (x); | |
271 | ||
272 | /* At this point, any valid address is accepted. */ | |
273 | GO_IF_LEGITIMATE_ADDRESS (mode, x, win); | |
274 | ||
275 | /* If it was valid before but breaking out memory refs invalidated it, | |
276 | use it the old way. */ | |
277 | if (memory_address_p (mode, oldx)) | |
278 | goto win2; | |
279 | ||
280 | /* Perform machine-dependent transformations on X | |
281 | in certain cases. This is not necessary since the code | |
282 | below can handle all possible cases, but machine-dependent | |
283 | transformations can make better code. */ | |
284 | LEGITIMIZE_ADDRESS (x, oldx, mode, win); | |
285 | ||
286 | /* PLUS and MULT can appear in special ways | |
287 | as the result of attempts to make an address usable for indexing. | |
288 | Usually they are dealt with by calling force_operand, below. | |
289 | But a sum containing constant terms is special | |
290 | if removing them makes the sum a valid address: | |
291 | then we generate that address in a register | |
292 | and index off of it. We do this because it often makes | |
293 | shorter code, and because the addresses thus generated | |
294 | in registers often become common subexpressions. */ | |
295 | if (GET_CODE (x) == PLUS) | |
296 | { | |
297 | int constant_term = 0; | |
298 | rtx y = eliminate_constant_term (x, &constant_term); | |
299 | if (constant_term == 0 | |
300 | || ! memory_address_p (mode, y)) | |
301 | return force_operand (x, 0); | |
302 | ||
303 | y = plus_constant (copy_to_reg (y), constant_term); | |
304 | if (! memory_address_p (mode, y)) | |
305 | return force_operand (x, 0); | |
306 | return y; | |
307 | } | |
308 | if (GET_CODE (x) == MULT || GET_CODE (x) == MINUS) | |
309 | return force_operand (x, 0); | |
310 | ||
311 | /* If we have a register that's an invalid address, | |
312 | it must be a hard reg of the wrong class. Copy it to a pseudo. */ | |
313 | if (GET_CODE (x) == REG) | |
314 | return copy_to_reg (x); | |
315 | ||
316 | /* Last resort: copy the value to a register, since | |
317 | the register is a valid address. */ | |
318 | return force_reg (Pmode, x); | |
319 | ||
320 | win2: | |
321 | x = oldx; | |
322 | win: | |
323 | if (flag_force_addr && optimize && GET_CODE (x) != REG | |
324 | /* Don't copy an addr via a reg if it is one of our stack slots. | |
325 | If we did, it would cause invalid REG_EQUIV notes for parms. */ | |
326 | && ! (GET_CODE (x) == PLUS | |
327 | && (XEXP (x, 0) == frame_pointer_rtx | |
328 | || XEXP (x, 0) == arg_pointer_rtx))) | |
329 | { | |
330 | if (general_operand (x, Pmode)) | |
331 | return force_reg (Pmode, x); | |
332 | else | |
333 | return force_operand (x, 0); | |
334 | } | |
335 | return x; | |
336 | } | |
337 | ||
338 | /* Like `memory_address' but pretend `flag_force_addr' is 0. */ | |
339 | ||
340 | rtx | |
341 | memory_address_noforce (mode, x) | |
342 | enum machine_mode mode; | |
343 | rtx x; | |
344 | { | |
345 | int ambient_force_addr = flag_force_addr; | |
346 | rtx val; | |
347 | ||
348 | flag_force_addr = 0; | |
349 | val = memory_address (mode, x); | |
350 | flag_force_addr = ambient_force_addr; | |
351 | return val; | |
352 | } | |
353 | \f | |
354 | /* Return a modified copy of X with its memory address copied | |
355 | into a temporary register to protect it from side effects. | |
356 | If X is not a MEM, it is returned unchanged (and not copied). | |
357 | Perhaps even if it is a MEM, if there is no need to change it. */ | |
358 | ||
359 | rtx | |
360 | stabilize (x) | |
361 | rtx x; | |
362 | { | |
363 | register rtx addr; | |
364 | if (GET_CODE (x) != MEM) | |
365 | return x; | |
366 | addr = XEXP (x, 0); | |
367 | if (rtx_unstable_p (addr)) | |
368 | { | |
369 | rtx temp = copy_all_regs (addr); | |
370 | rtx mem; | |
371 | if (GET_CODE (temp) != REG) | |
372 | temp = copy_to_reg (temp); | |
373 | mem = gen_rtx (MEM, GET_MODE (x), temp); | |
374 | /* Mark returned memref with in_struct | |
375 | if it's in an array or structure. */ | |
376 | if (GET_CODE (addr) == PLUS || MEM_IN_STRUCT_P (x)) | |
377 | MEM_IN_STRUCT_P (mem) = 1; | |
378 | return mem; | |
379 | } | |
380 | return x; | |
381 | } | |
382 | \f | |
383 | /* Copy the value or contents of X to a new temp reg and return that reg. */ | |
384 | ||
385 | rtx | |
386 | copy_to_reg (x) | |
387 | rtx x; | |
388 | { | |
389 | register rtx temp = gen_reg_rtx (GET_MODE (x)); | |
390 | ||
391 | /* If not an operand, must be an address with PLUS and MULT so | |
392 | do the computation. */ | |
393 | if (! general_operand (x, VOIDmode)) | |
394 | x = force_operand (x, temp); | |
395 | ||
396 | if (x != temp) | |
397 | emit_move_insn (temp, x); | |
398 | ||
399 | return temp; | |
400 | } | |
401 | ||
402 | /* Like copy_to_reg but always give the new register mode Pmode | |
403 | in case X is a constant. */ | |
404 | ||
405 | rtx | |
406 | copy_addr_to_reg (x) | |
407 | rtx x; | |
408 | { | |
409 | return copy_to_mode_reg (Pmode, x); | |
410 | } | |
411 | ||
412 | /* Like copy_to_reg but always give the new register mode MODE | |
413 | in case X is a constant. */ | |
414 | ||
415 | rtx | |
416 | copy_to_mode_reg (mode, x) | |
417 | enum machine_mode mode; | |
418 | rtx x; | |
419 | { | |
420 | register rtx temp = gen_reg_rtx (mode); | |
421 | ||
422 | /* If not an operand, must be an address with PLUS and MULT so | |
423 | do the computation. */ | |
424 | if (! general_operand (x, VOIDmode)) | |
425 | x = force_operand (x, temp); | |
426 | ||
427 | if (GET_MODE (x) != mode && GET_MODE (x) != VOIDmode) | |
428 | abort (); | |
429 | if (x != temp) | |
430 | emit_move_insn (temp, x); | |
431 | return temp; | |
432 | } | |
433 | ||
434 | /* Load X into a register if it is not already one. | |
435 | Use mode MODE for the register. | |
436 | X should be valid for mode MODE, but it may be a constant which | |
437 | is valid for all integer modes; that's why caller must specify MODE. | |
438 | ||
439 | The caller must not alter the value in the register we return, | |
440 | since we mark it as a "constant" register. */ | |
441 | ||
442 | rtx | |
443 | force_reg (mode, x) | |
444 | enum machine_mode mode; | |
445 | rtx x; | |
446 | { | |
447 | register rtx temp, insn; | |
448 | ||
449 | if (GET_CODE (x) == REG) | |
450 | return x; | |
451 | temp = gen_reg_rtx (mode); | |
452 | insn = emit_move_insn (temp, x); | |
453 | /* Let optimizers know that TEMP's value never changes | |
454 | and that X can be substituted for it. */ | |
455 | if (CONSTANT_P (x)) | |
456 | REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_EQUIV, x, REG_NOTES (insn)); | |
457 | return temp; | |
458 | } | |
459 | ||
460 | /* If X is a memory ref, copy its contents to a new temp reg and return | |
461 | that reg. Otherwise, return X. */ | |
462 | ||
463 | rtx | |
464 | force_not_mem (x) | |
465 | rtx x; | |
466 | { | |
467 | register rtx temp; | |
468 | if (GET_CODE (x) != MEM) | |
469 | return x; | |
470 | temp = gen_reg_rtx (GET_MODE (x)); | |
471 | emit_move_insn (temp, x); | |
472 | return temp; | |
473 | } | |
474 | ||
475 | /* Copy X to TARGET (if it's nonzero and a reg) | |
476 | or to a new temp reg and return that reg. */ | |
477 | ||
478 | rtx | |
479 | copy_to_suggested_reg (x, target) | |
480 | rtx x, target; | |
481 | { | |
482 | register rtx temp; | |
483 | if (target && GET_CODE (target) == REG) | |
484 | temp = target; | |
485 | else | |
486 | temp = gen_reg_rtx (GET_MODE (x)); | |
487 | emit_move_insn (temp, x); | |
488 | return temp; | |
489 | } | |
490 | \f | |
491 | /* Adjust the stack pointer by ADJUST (an rtx for a number of bytes). | |
492 | This pops when ADJUST is positive. ADJUST need not be constant. */ | |
493 | ||
494 | void | |
495 | adjust_stack (adjust) | |
496 | rtx adjust; | |
497 | { | |
498 | adjust = protect_from_queue (adjust, 0); | |
499 | ||
500 | #ifdef STACK_GROWS_DOWNWARD | |
501 | emit_insn (gen_add2_insn (stack_pointer_rtx, adjust)); | |
502 | #else | |
503 | emit_insn (gen_sub2_insn (stack_pointer_rtx, adjust)); | |
504 | #endif | |
505 | } | |
506 | ||
507 | /* Adjust the stack pointer by minus ADJUST (an rtx for a number of bytes). | |
508 | This pushes when ADJUST is positive. ADJUST need not be constant. */ | |
509 | ||
510 | void | |
511 | anti_adjust_stack (adjust) | |
512 | rtx adjust; | |
513 | { | |
514 | adjust = protect_from_queue (adjust, 0); | |
515 | ||
516 | #ifdef STACK_GROWS_DOWNWARD | |
517 | emit_insn (gen_sub2_insn (stack_pointer_rtx, adjust)); | |
518 | #else | |
519 | emit_insn (gen_add2_insn (stack_pointer_rtx, adjust)); | |
520 | #endif | |
521 | } | |
522 | ||
523 | /* Round the size of a block to be pushed up to the boundary required | |
524 | by this machine. SIZE is the desired size, which need not be constant. */ | |
525 | ||
526 | rtx | |
527 | round_push (size) | |
528 | rtx size; | |
529 | { | |
530 | #ifdef STACK_BOUNDARY | |
531 | int align = STACK_BOUNDARY / BITS_PER_UNIT; | |
532 | if (align == 1) | |
533 | return size; | |
534 | if (GET_CODE (size) == CONST_INT) | |
535 | { | |
536 | int new = (INTVAL (size) + align - 1) / align * align; | |
537 | if (INTVAL (size) != new) | |
538 | size = gen_rtx (CONST_INT, VOIDmode, new); | |
539 | } | |
540 | else | |
541 | { | |
542 | size = expand_divmod (0, CEIL_DIV_EXPR, Pmode, size, | |
543 | gen_rtx (CONST_INT, VOIDmode, align), | |
544 | 0, 1); | |
545 | size = expand_mult (Pmode, size, | |
546 | gen_rtx (CONST_INT, VOIDmode, align), | |
547 | 0, 1); | |
548 | } | |
549 | #endif /* STACK_BOUNDARY */ | |
550 | return size; | |
551 | } | |
552 | ||
553 | /* Return an rtx representing the register or memory location | |
554 | in which a scalar value of data type VALTYPE | |
555 | was returned by a function call to function FUNC. | |
556 | FUNC is a FUNCTION_DECL node if the precise function is known, | |
557 | otherwise 0. */ | |
558 | ||
559 | rtx | |
560 | hard_function_value (valtype, func) | |
561 | tree valtype; | |
562 | tree func; | |
563 | { | |
564 | return FUNCTION_VALUE (valtype, func); | |
565 | } | |
566 | ||
567 | /* Return an rtx representing the register or memory location | |
568 | in which a scalar value of mode MODE was returned by a library call. */ | |
569 | ||
570 | rtx | |
571 | hard_libcall_value (mode) | |
572 | enum machine_mode mode; | |
573 | { | |
574 | return LIBCALL_VALUE (mode); | |
575 | } |