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a6c787e5 | 1 | /* Pass computing data for optimizing stdarg functions. |
2 | Copyright (C) 2004, 2005 Free Software Foundation, Inc. | |
3 | Contributed by Jakub Jelinek <jakub@redhat.com> | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to | |
67ce556b | 19 | the Free Software Foundation, 51 Franklin Street, Fifth Floor, |
20 | Boston, MA 02110-1301, USA. */ | |
a6c787e5 | 21 | |
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "tree.h" | |
27 | #include "function.h" | |
28 | #include "langhooks.h" | |
29 | #include "diagnostic.h" | |
30 | #include "target.h" | |
31 | #include "tree-flow.h" | |
32 | #include "tree-pass.h" | |
33 | #include "tree-stdarg.h" | |
34 | ||
35 | /* A simple pass that attempts to optimize stdarg functions on architectures | |
36 | that need to save register arguments to stack on entry to stdarg functions. | |
37 | If the function doesn't use any va_start macros, no registers need to | |
38 | be saved. If va_start macros are used, the va_list variables don't escape | |
39 | the function, it is only necessary to save registers that will be used | |
40 | in va_arg macros. E.g. if va_arg is only used with integral types | |
41 | in the function, floating point registers don't need to be saved, etc. */ | |
42 | ||
43 | ||
44 | /* Return true if basic block VA_ARG_BB is dominated by VA_START_BB and | |
45 | is executed at most as many times as VA_START_BB. */ | |
46 | ||
47 | static bool | |
48 | reachable_at_most_once (basic_block va_arg_bb, basic_block va_start_bb) | |
49 | { | |
50 | edge *stack, e; | |
51 | edge_iterator ei; | |
52 | int sp; | |
53 | sbitmap visited; | |
54 | bool ret; | |
55 | ||
56 | if (va_arg_bb == va_start_bb) | |
57 | return true; | |
58 | ||
59 | if (! dominated_by_p (CDI_DOMINATORS, va_arg_bb, va_start_bb)) | |
60 | return false; | |
61 | ||
62 | stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge)); | |
63 | sp = 0; | |
64 | ||
65 | visited = sbitmap_alloc (last_basic_block); | |
66 | sbitmap_zero (visited); | |
67 | ret = true; | |
68 | ||
69 | FOR_EACH_EDGE (e, ei, va_arg_bb->preds) | |
70 | stack[sp++] = e; | |
71 | ||
72 | while (sp) | |
73 | { | |
74 | basic_block src; | |
75 | ||
76 | --sp; | |
77 | e = stack[sp]; | |
78 | src = e->src; | |
79 | ||
80 | if (e->flags & EDGE_COMPLEX) | |
81 | { | |
82 | ret = false; | |
83 | break; | |
84 | } | |
85 | ||
86 | if (src == va_start_bb) | |
87 | continue; | |
88 | ||
89 | /* va_arg_bb can be executed more times than va_start_bb. */ | |
90 | if (src == va_arg_bb) | |
91 | { | |
92 | ret = false; | |
93 | break; | |
94 | } | |
95 | ||
96 | gcc_assert (src != ENTRY_BLOCK_PTR); | |
97 | ||
98 | if (! TEST_BIT (visited, src->index)) | |
99 | { | |
100 | SET_BIT (visited, src->index); | |
101 | FOR_EACH_EDGE (e, ei, src->preds) | |
102 | stack[sp++] = e; | |
103 | } | |
104 | } | |
105 | ||
106 | free (stack); | |
107 | sbitmap_free (visited); | |
108 | return ret; | |
109 | } | |
110 | ||
111 | ||
112 | /* For statement COUNTER = RHS, if RHS is COUNTER + constant, | |
113 | return constant, otherwise return (unsigned HOST_WIDE_INT) -1. | |
114 | GPR_P is true if this is GPR counter. */ | |
115 | ||
116 | static unsigned HOST_WIDE_INT | |
117 | va_list_counter_bump (struct stdarg_info *si, tree counter, tree rhs, | |
118 | bool gpr_p) | |
119 | { | |
120 | tree stmt, lhs, orig_lhs; | |
121 | unsigned HOST_WIDE_INT ret = 0, val, counter_val; | |
122 | unsigned int max_size; | |
123 | ||
124 | if (si->offsets == NULL) | |
125 | { | |
126 | unsigned int i; | |
127 | ||
128 | si->offsets = xmalloc (num_ssa_names * sizeof (int)); | |
129 | for (i = 0; i < num_ssa_names; ++i) | |
130 | si->offsets[i] = -1; | |
131 | } | |
132 | ||
133 | counter_val = gpr_p ? cfun->va_list_gpr_size : cfun->va_list_fpr_size; | |
134 | max_size = gpr_p ? VA_LIST_MAX_GPR_SIZE : VA_LIST_MAX_FPR_SIZE; | |
135 | orig_lhs = lhs = rhs; | |
136 | while (lhs) | |
137 | { | |
138 | if (si->offsets[SSA_NAME_VERSION (lhs)] != -1) | |
139 | { | |
140 | if (counter_val >= max_size) | |
141 | { | |
142 | ret = max_size; | |
143 | break; | |
144 | } | |
145 | ||
146 | ret -= counter_val - si->offsets[SSA_NAME_VERSION (lhs)]; | |
147 | break; | |
148 | } | |
149 | ||
150 | stmt = SSA_NAME_DEF_STMT (lhs); | |
151 | ||
152 | if (TREE_CODE (stmt) != MODIFY_EXPR | |
153 | || TREE_OPERAND (stmt, 0) != lhs) | |
154 | return (unsigned HOST_WIDE_INT) -1; | |
155 | ||
156 | rhs = TREE_OPERAND (stmt, 1); | |
157 | if (TREE_CODE (rhs) == WITH_SIZE_EXPR) | |
158 | rhs = TREE_OPERAND (rhs, 0); | |
159 | ||
160 | if (TREE_CODE (rhs) == SSA_NAME) | |
161 | { | |
162 | lhs = rhs; | |
163 | continue; | |
164 | } | |
165 | ||
166 | if ((TREE_CODE (rhs) == NOP_EXPR | |
167 | || TREE_CODE (rhs) == CONVERT_EXPR) | |
168 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
169 | { | |
170 | lhs = TREE_OPERAND (rhs, 0); | |
171 | continue; | |
172 | } | |
173 | ||
174 | if (TREE_CODE (rhs) == PLUS_EXPR | |
175 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME | |
176 | && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST | |
177 | && host_integerp (TREE_OPERAND (rhs, 1), 1)) | |
178 | { | |
179 | ret += tree_low_cst (TREE_OPERAND (rhs, 1), 1); | |
180 | lhs = TREE_OPERAND (rhs, 0); | |
181 | continue; | |
182 | } | |
183 | ||
184 | if (TREE_CODE (counter) != TREE_CODE (rhs)) | |
185 | return (unsigned HOST_WIDE_INT) -1; | |
186 | ||
187 | if (TREE_CODE (counter) == COMPONENT_REF) | |
188 | { | |
189 | if (get_base_address (counter) != get_base_address (rhs) | |
190 | || TREE_CODE (TREE_OPERAND (rhs, 1)) != FIELD_DECL | |
191 | || TREE_OPERAND (counter, 1) != TREE_OPERAND (rhs, 1)) | |
192 | return (unsigned HOST_WIDE_INT) -1; | |
193 | } | |
194 | else if (counter != rhs) | |
195 | return (unsigned HOST_WIDE_INT) -1; | |
196 | ||
197 | lhs = NULL; | |
198 | } | |
199 | ||
200 | lhs = orig_lhs; | |
201 | val = ret + counter_val; | |
202 | while (lhs) | |
203 | { | |
204 | if (si->offsets[SSA_NAME_VERSION (lhs)] != -1) | |
205 | break; | |
206 | ||
207 | if (val >= max_size) | |
208 | si->offsets[SSA_NAME_VERSION (lhs)] = max_size; | |
209 | else | |
210 | si->offsets[SSA_NAME_VERSION (lhs)] = val; | |
211 | ||
212 | stmt = SSA_NAME_DEF_STMT (lhs); | |
213 | ||
214 | rhs = TREE_OPERAND (stmt, 1); | |
215 | if (TREE_CODE (rhs) == WITH_SIZE_EXPR) | |
216 | rhs = TREE_OPERAND (rhs, 0); | |
217 | ||
218 | if (TREE_CODE (rhs) == SSA_NAME) | |
219 | { | |
220 | lhs = rhs; | |
221 | continue; | |
222 | } | |
223 | ||
224 | if ((TREE_CODE (rhs) == NOP_EXPR | |
225 | || TREE_CODE (rhs) == CONVERT_EXPR) | |
226 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
227 | { | |
228 | lhs = TREE_OPERAND (rhs, 0); | |
229 | continue; | |
230 | } | |
231 | ||
232 | if (TREE_CODE (rhs) == PLUS_EXPR | |
233 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME | |
234 | && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST | |
235 | && host_integerp (TREE_OPERAND (rhs, 1), 1)) | |
236 | { | |
237 | val -= tree_low_cst (TREE_OPERAND (rhs, 1), 1); | |
238 | lhs = TREE_OPERAND (rhs, 0); | |
239 | continue; | |
240 | } | |
241 | ||
242 | lhs = NULL; | |
243 | } | |
244 | ||
245 | return ret; | |
246 | } | |
247 | ||
248 | ||
249 | /* Called by walk_tree to look for references to va_list variables. */ | |
250 | ||
251 | static tree | |
252 | find_va_list_reference (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, | |
253 | void *data) | |
254 | { | |
255 | bitmap va_list_vars = (bitmap) data; | |
256 | tree var = *tp; | |
257 | ||
258 | if (TREE_CODE (var) == SSA_NAME) | |
259 | var = SSA_NAME_VAR (var); | |
260 | ||
261 | if (TREE_CODE (var) == VAR_DECL | |
a55dc2cd | 262 | && bitmap_bit_p (va_list_vars, DECL_UID (var))) |
a6c787e5 | 263 | return var; |
264 | ||
265 | return NULL_TREE; | |
266 | } | |
267 | ||
268 | ||
269 | /* Helper function of va_list_counter_struct_op. Compute | |
270 | cfun->va_list_{g,f}pr_size. AP is a va_list GPR/FPR counter, | |
271 | if WRITE_P is true, seen in AP = VAR, otherwise seen in VAR = AP | |
272 | statement. GPR_P is true if AP is a GPR counter, false if it is | |
273 | a FPR counter. */ | |
274 | ||
275 | static void | |
276 | va_list_counter_op (struct stdarg_info *si, tree ap, tree var, bool gpr_p, | |
277 | bool write_p) | |
278 | { | |
279 | unsigned HOST_WIDE_INT increment; | |
280 | ||
281 | if (si->compute_sizes < 0) | |
282 | { | |
283 | si->compute_sizes = 0; | |
284 | if (si->va_start_count == 1 | |
285 | && reachable_at_most_once (si->bb, si->va_start_bb)) | |
286 | si->compute_sizes = 1; | |
287 | ||
288 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
289 | fprintf (dump_file, | |
290 | "bb%d will %sbe executed at most once for each va_start " | |
291 | "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", | |
292 | si->va_start_bb->index); | |
293 | } | |
294 | ||
295 | if (write_p | |
296 | && si->compute_sizes | |
297 | && (increment = va_list_counter_bump (si, ap, var, gpr_p)) + 1 > 1) | |
298 | { | |
299 | if (gpr_p && cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE) | |
300 | { | |
301 | cfun->va_list_gpr_size += increment; | |
302 | return; | |
303 | } | |
304 | ||
305 | if (!gpr_p && cfun->va_list_fpr_size + increment < VA_LIST_MAX_FPR_SIZE) | |
306 | { | |
307 | cfun->va_list_fpr_size += increment; | |
308 | return; | |
309 | } | |
310 | } | |
311 | ||
312 | if (write_p || !si->compute_sizes) | |
313 | { | |
314 | if (gpr_p) | |
315 | cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; | |
316 | else | |
317 | cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; | |
318 | } | |
319 | } | |
320 | ||
321 | ||
322 | /* If AP is a va_list GPR/FPR counter, compute cfun->va_list_{g,f}pr_size. | |
323 | If WRITE_P is true, AP has been seen in AP = VAR assignment, if WRITE_P | |
324 | is false, AP has been seen in VAR = AP assignment. | |
325 | Return true if the AP = VAR (resp. VAR = AP) statement is a recognized | |
326 | va_arg operation that doesn't cause the va_list variable to escape | |
327 | current function. */ | |
328 | ||
329 | static bool | |
330 | va_list_counter_struct_op (struct stdarg_info *si, tree ap, tree var, | |
331 | bool write_p) | |
332 | { | |
333 | tree base; | |
334 | ||
335 | if (TREE_CODE (ap) != COMPONENT_REF | |
336 | || TREE_CODE (TREE_OPERAND (ap, 1)) != FIELD_DECL) | |
337 | return false; | |
338 | ||
339 | if (TREE_CODE (var) != SSA_NAME | |
a55dc2cd | 340 | || bitmap_bit_p (si->va_list_vars, DECL_UID (SSA_NAME_VAR (var)))) |
a6c787e5 | 341 | return false; |
342 | ||
343 | base = get_base_address (ap); | |
344 | if (TREE_CODE (base) != VAR_DECL | |
a55dc2cd | 345 | || !bitmap_bit_p (si->va_list_vars, DECL_UID (base))) |
a6c787e5 | 346 | return false; |
347 | ||
348 | if (TREE_OPERAND (ap, 1) == va_list_gpr_counter_field) | |
349 | va_list_counter_op (si, ap, var, true, write_p); | |
350 | else if (TREE_OPERAND (ap, 1) == va_list_fpr_counter_field) | |
351 | va_list_counter_op (si, ap, var, false, write_p); | |
352 | ||
353 | return true; | |
354 | } | |
355 | ||
356 | ||
357 | /* Check for TEM = AP. Return true if found and the caller shouldn't | |
358 | search for va_list references in the statement. */ | |
359 | ||
360 | static bool | |
361 | va_list_ptr_read (struct stdarg_info *si, tree ap, tree tem) | |
362 | { | |
363 | if (TREE_CODE (ap) != VAR_DECL | |
a55dc2cd | 364 | || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap))) |
a6c787e5 | 365 | return false; |
366 | ||
367 | if (TREE_CODE (tem) != SSA_NAME | |
368 | || bitmap_bit_p (si->va_list_vars, | |
a55dc2cd | 369 | DECL_UID (SSA_NAME_VAR (tem))) |
a6c787e5 | 370 | || is_global_var (SSA_NAME_VAR (tem))) |
371 | return false; | |
372 | ||
373 | if (si->compute_sizes < 0) | |
374 | { | |
375 | si->compute_sizes = 0; | |
376 | if (si->va_start_count == 1 | |
377 | && reachable_at_most_once (si->bb, si->va_start_bb)) | |
378 | si->compute_sizes = 1; | |
379 | ||
380 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
381 | fprintf (dump_file, | |
382 | "bb%d will %sbe executed at most once for each va_start " | |
383 | "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", | |
384 | si->va_start_bb->index); | |
385 | } | |
386 | ||
387 | /* For void * or char * va_list types, there is just one counter. | |
388 | If va_arg is used in a loop, we don't know how many registers need | |
389 | saving. */ | |
390 | if (! si->compute_sizes) | |
391 | return false; | |
392 | ||
393 | if (va_list_counter_bump (si, ap, tem, true) == (unsigned HOST_WIDE_INT) -1) | |
394 | return false; | |
395 | ||
396 | /* Note the temporary, as we need to track whether it doesn't escape | |
397 | the current function. */ | |
398 | bitmap_set_bit (si->va_list_escape_vars, | |
a55dc2cd | 399 | DECL_UID (SSA_NAME_VAR (tem))); |
a6c787e5 | 400 | return true; |
401 | } | |
402 | ||
403 | ||
404 | /* Check for: | |
405 | tem1 = AP; | |
406 | TEM2 = tem1 + CST; | |
407 | AP = TEM2; | |
408 | sequence and update cfun->va_list_gpr_size. Return true if found. */ | |
409 | ||
410 | static bool | |
411 | va_list_ptr_write (struct stdarg_info *si, tree ap, tree tem2) | |
412 | { | |
413 | unsigned HOST_WIDE_INT increment; | |
414 | ||
415 | if (TREE_CODE (ap) != VAR_DECL | |
a55dc2cd | 416 | || !bitmap_bit_p (si->va_list_vars, DECL_UID (ap))) |
a6c787e5 | 417 | return false; |
418 | ||
419 | if (TREE_CODE (tem2) != SSA_NAME | |
a55dc2cd | 420 | || bitmap_bit_p (si->va_list_vars, DECL_UID (SSA_NAME_VAR (tem2)))) |
a6c787e5 | 421 | return false; |
422 | ||
423 | if (si->compute_sizes <= 0) | |
424 | return false; | |
425 | ||
426 | increment = va_list_counter_bump (si, ap, tem2, true); | |
427 | if (increment + 1 <= 1) | |
428 | return false; | |
429 | ||
430 | if (cfun->va_list_gpr_size + increment < VA_LIST_MAX_GPR_SIZE) | |
431 | cfun->va_list_gpr_size += increment; | |
432 | else | |
433 | cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; | |
434 | ||
435 | return true; | |
436 | } | |
437 | ||
438 | ||
439 | /* If RHS is X, (some type *) X or X + CST for X a temporary variable | |
440 | containing value of some va_list variable plus optionally some constant, | |
441 | either set si->va_list_escapes or add LHS to si->va_list_escape_vars, | |
442 | depending whether LHS is a function local temporary. */ | |
443 | ||
444 | static void | |
445 | check_va_list_escapes (struct stdarg_info *si, tree lhs, tree rhs) | |
446 | { | |
447 | if (! POINTER_TYPE_P (TREE_TYPE (rhs))) | |
448 | return; | |
449 | ||
450 | if ((TREE_CODE (rhs) == PLUS_EXPR | |
451 | && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST) | |
452 | || TREE_CODE (rhs) == NOP_EXPR | |
453 | || TREE_CODE (rhs) == CONVERT_EXPR) | |
454 | rhs = TREE_OPERAND (rhs, 0); | |
455 | ||
456 | if (TREE_CODE (rhs) != SSA_NAME | |
457 | || ! bitmap_bit_p (si->va_list_escape_vars, | |
a55dc2cd | 458 | DECL_UID (SSA_NAME_VAR (rhs)))) |
a6c787e5 | 459 | return; |
460 | ||
461 | if (TREE_CODE (lhs) != SSA_NAME || is_global_var (SSA_NAME_VAR (lhs))) | |
462 | { | |
463 | si->va_list_escapes = true; | |
464 | return; | |
465 | } | |
466 | ||
467 | if (si->compute_sizes < 0) | |
468 | { | |
469 | si->compute_sizes = 0; | |
470 | if (si->va_start_count == 1 | |
471 | && reachable_at_most_once (si->bb, si->va_start_bb)) | |
472 | si->compute_sizes = 1; | |
473 | ||
474 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
475 | fprintf (dump_file, | |
476 | "bb%d will %sbe executed at most once for each va_start " | |
477 | "in bb%d\n", si->bb->index, si->compute_sizes ? "" : "not ", | |
478 | si->va_start_bb->index); | |
479 | } | |
480 | ||
481 | /* For void * or char * va_list types, there is just one counter. | |
482 | If va_arg is used in a loop, we don't know how many registers need | |
483 | saving. */ | |
484 | if (! si->compute_sizes) | |
485 | { | |
486 | si->va_list_escapes = true; | |
487 | return; | |
488 | } | |
489 | ||
490 | if (va_list_counter_bump (si, si->va_start_ap, lhs, true) | |
491 | == (unsigned HOST_WIDE_INT) -1) | |
492 | { | |
493 | si->va_list_escapes = true; | |
494 | return; | |
495 | } | |
496 | ||
497 | bitmap_set_bit (si->va_list_escape_vars, | |
a55dc2cd | 498 | DECL_UID (SSA_NAME_VAR (lhs))); |
a6c787e5 | 499 | } |
500 | ||
501 | ||
502 | /* Check all uses of temporaries from si->va_list_escape_vars bitmap. | |
503 | Return true if va_list might be escaping. */ | |
504 | ||
505 | static bool | |
506 | check_all_va_list_escapes (struct stdarg_info *si) | |
507 | { | |
508 | basic_block bb; | |
509 | ||
510 | FOR_EACH_BB (bb) | |
511 | { | |
512 | block_stmt_iterator i; | |
513 | ||
514 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
515 | { | |
516 | tree stmt = bsi_stmt (i), use; | |
517 | ssa_op_iter iter; | |
518 | ||
519 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES) | |
520 | { | |
521 | if (! bitmap_bit_p (si->va_list_escape_vars, | |
a55dc2cd | 522 | DECL_UID (SSA_NAME_VAR (use)))) |
a6c787e5 | 523 | continue; |
524 | ||
525 | if (TREE_CODE (stmt) == MODIFY_EXPR) | |
526 | { | |
527 | tree lhs = TREE_OPERAND (stmt, 0); | |
528 | tree rhs = TREE_OPERAND (stmt, 1); | |
529 | ||
530 | if (TREE_CODE (rhs) == WITH_SIZE_EXPR) | |
531 | rhs = TREE_OPERAND (rhs, 0); | |
532 | ||
533 | /* x = *ap_temp; */ | |
534 | if (TREE_CODE (rhs) == INDIRECT_REF | |
535 | && TREE_OPERAND (rhs, 0) == use | |
536 | && TYPE_SIZE_UNIT (TREE_TYPE (rhs)) | |
537 | && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (rhs)), 1) | |
538 | && si->offsets[SSA_NAME_VERSION (use)] != -1) | |
539 | { | |
540 | unsigned HOST_WIDE_INT gpr_size; | |
541 | tree access_size = TYPE_SIZE_UNIT (TREE_TYPE (rhs)); | |
542 | ||
543 | gpr_size = si->offsets[SSA_NAME_VERSION (use)] | |
544 | + tree_low_cst (access_size, 1); | |
545 | if (gpr_size >= VA_LIST_MAX_GPR_SIZE) | |
546 | cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; | |
547 | else if (gpr_size > cfun->va_list_gpr_size) | |
548 | cfun->va_list_gpr_size = gpr_size; | |
549 | continue; | |
550 | } | |
551 | ||
552 | /* va_arg sequences may contain | |
553 | other_ap_temp = ap_temp; | |
554 | other_ap_temp = ap_temp + constant; | |
555 | other_ap_temp = (some_type *) ap_temp; | |
556 | ap = ap_temp; | |
557 | statements. */ | |
558 | if ((TREE_CODE (rhs) == PLUS_EXPR | |
559 | && TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST) | |
560 | || TREE_CODE (rhs) == NOP_EXPR | |
561 | || TREE_CODE (rhs) == CONVERT_EXPR) | |
562 | rhs = TREE_OPERAND (rhs, 0); | |
563 | ||
564 | if (rhs == use) | |
565 | { | |
566 | if (TREE_CODE (lhs) == SSA_NAME | |
567 | && bitmap_bit_p (si->va_list_escape_vars, | |
a55dc2cd | 568 | DECL_UID (SSA_NAME_VAR (lhs)))) |
a6c787e5 | 569 | continue; |
570 | ||
571 | if (TREE_CODE (lhs) == VAR_DECL | |
572 | && bitmap_bit_p (si->va_list_vars, | |
a55dc2cd | 573 | DECL_UID (lhs))) |
a6c787e5 | 574 | continue; |
575 | } | |
576 | } | |
577 | ||
578 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
579 | { | |
580 | fputs ("va_list escapes in ", dump_file); | |
581 | print_generic_expr (dump_file, stmt, dump_flags); | |
582 | fputc ('\n', dump_file); | |
583 | } | |
584 | return true; | |
585 | } | |
586 | } | |
587 | } | |
588 | ||
589 | return false; | |
590 | } | |
591 | ||
592 | ||
593 | /* Return true if this optimization pass should be done. | |
594 | It makes only sense for stdarg functions. */ | |
595 | ||
596 | static bool | |
597 | gate_optimize_stdarg (void) | |
598 | { | |
599 | /* This optimization is only for stdarg functions. */ | |
600 | return current_function_stdarg != 0; | |
601 | } | |
602 | ||
603 | ||
604 | /* Entry point to the stdarg optimization pass. */ | |
605 | ||
606 | static void | |
607 | execute_optimize_stdarg (void) | |
608 | { | |
609 | basic_block bb; | |
610 | bool va_list_escapes = false; | |
611 | bool va_list_simple_ptr; | |
612 | struct stdarg_info si; | |
613 | const char *funcname = NULL; | |
614 | ||
615 | cfun->va_list_gpr_size = 0; | |
616 | cfun->va_list_fpr_size = 0; | |
617 | memset (&si, 0, sizeof (si)); | |
618 | si.va_list_vars = BITMAP_ALLOC (NULL); | |
619 | si.va_list_escape_vars = BITMAP_ALLOC (NULL); | |
620 | ||
621 | if (dump_file) | |
622 | funcname = lang_hooks.decl_printable_name (current_function_decl, 2); | |
623 | ||
624 | va_list_simple_ptr = POINTER_TYPE_P (va_list_type_node) | |
625 | && (TREE_TYPE (va_list_type_node) == void_type_node | |
626 | || TREE_TYPE (va_list_type_node) == char_type_node); | |
627 | ||
628 | FOR_EACH_BB (bb) | |
629 | { | |
630 | block_stmt_iterator i; | |
631 | ||
632 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
633 | { | |
634 | tree stmt = bsi_stmt (i); | |
635 | tree call = get_call_expr_in (stmt), callee; | |
636 | tree ap; | |
637 | ||
638 | if (!call) | |
639 | continue; | |
640 | ||
641 | callee = get_callee_fndecl (call); | |
642 | if (!callee | |
643 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
644 | continue; | |
645 | ||
646 | switch (DECL_FUNCTION_CODE (callee)) | |
647 | { | |
648 | case BUILT_IN_VA_START: | |
649 | break; | |
650 | /* If old style builtins are used, don't optimize anything. */ | |
651 | case BUILT_IN_SAVEREGS: | |
652 | case BUILT_IN_STDARG_START: | |
653 | case BUILT_IN_ARGS_INFO: | |
654 | case BUILT_IN_NEXT_ARG: | |
655 | va_list_escapes = true; | |
656 | continue; | |
657 | default: | |
658 | continue; | |
659 | } | |
660 | ||
661 | si.va_start_count++; | |
662 | ap = TREE_VALUE (TREE_OPERAND (call, 1)); | |
8b151587 | 663 | |
664 | if (TREE_CODE (ap) != ADDR_EXPR) | |
a6c787e5 | 665 | { |
666 | va_list_escapes = true; | |
667 | break; | |
668 | } | |
a6c787e5 | 669 | ap = TREE_OPERAND (ap, 0); |
8b151587 | 670 | if (TREE_CODE (ap) == ARRAY_REF) |
671 | { | |
672 | if (! integer_zerop (TREE_OPERAND (ap, 1))) | |
673 | { | |
674 | va_list_escapes = true; | |
675 | break; | |
676 | } | |
677 | ap = TREE_OPERAND (ap, 0); | |
678 | } | |
679 | if (TYPE_MAIN_VARIANT (TREE_TYPE (ap)) | |
680 | != TYPE_MAIN_VARIANT (va_list_type_node) | |
681 | || TREE_CODE (ap) != VAR_DECL) | |
682 | { | |
683 | va_list_escapes = true; | |
684 | break; | |
685 | } | |
686 | ||
a6c787e5 | 687 | if (is_global_var (ap)) |
688 | { | |
689 | va_list_escapes = true; | |
690 | break; | |
691 | } | |
692 | ||
a55dc2cd | 693 | bitmap_set_bit (si.va_list_vars, DECL_UID (ap)); |
a6c787e5 | 694 | |
695 | /* VA_START_BB and VA_START_AP will be only used if there is just | |
696 | one va_start in the function. */ | |
697 | si.va_start_bb = bb; | |
698 | si.va_start_ap = ap; | |
699 | } | |
700 | ||
701 | if (va_list_escapes) | |
702 | break; | |
703 | } | |
704 | ||
705 | /* If there were no va_start uses in the function, there is no need to | |
706 | save anything. */ | |
707 | if (si.va_start_count == 0) | |
708 | goto finish; | |
709 | ||
710 | /* If some va_list arguments weren't local, we can't optimize. */ | |
711 | if (va_list_escapes) | |
712 | goto finish; | |
713 | ||
714 | /* For void * or char * va_list, something useful can be done only | |
715 | if there is just one va_start. */ | |
716 | if (va_list_simple_ptr && si.va_start_count > 1) | |
717 | { | |
718 | va_list_escapes = true; | |
719 | goto finish; | |
720 | } | |
721 | ||
722 | /* For struct * va_list, if the backend didn't tell us what the counter fields | |
723 | are, there is nothing more we can do. */ | |
724 | if (!va_list_simple_ptr | |
725 | && va_list_gpr_counter_field == NULL_TREE | |
726 | && va_list_fpr_counter_field == NULL_TREE) | |
727 | { | |
728 | va_list_escapes = true; | |
729 | goto finish; | |
730 | } | |
731 | ||
732 | /* For void * or char * va_list there is just one counter | |
733 | (va_list itself). Use VA_LIST_GPR_SIZE for it. */ | |
734 | if (va_list_simple_ptr) | |
735 | cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; | |
736 | ||
737 | FOR_EACH_BB (bb) | |
738 | { | |
739 | block_stmt_iterator i; | |
740 | ||
741 | si.compute_sizes = -1; | |
742 | si.bb = bb; | |
743 | for (i = bsi_start (bb); | |
744 | !bsi_end_p (i) && !va_list_escapes; | |
745 | bsi_next (&i)) | |
746 | { | |
747 | tree stmt = bsi_stmt (i); | |
748 | tree call; | |
749 | ||
750 | /* Don't look at __builtin_va_{start,end}, they are ok. */ | |
751 | call = get_call_expr_in (stmt); | |
752 | if (call) | |
753 | { | |
754 | tree callee = get_callee_fndecl (call); | |
755 | ||
756 | if (callee | |
757 | && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL | |
758 | && (DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_START | |
759 | || DECL_FUNCTION_CODE (callee) == BUILT_IN_VA_END)) | |
760 | continue; | |
761 | } | |
762 | ||
763 | if (TREE_CODE (stmt) == MODIFY_EXPR) | |
764 | { | |
765 | tree lhs = TREE_OPERAND (stmt, 0); | |
766 | tree rhs = TREE_OPERAND (stmt, 1); | |
767 | ||
768 | if (TREE_CODE (rhs) == WITH_SIZE_EXPR) | |
769 | rhs = TREE_OPERAND (rhs, 0); | |
770 | ||
771 | if (va_list_simple_ptr) | |
772 | { | |
773 | /* Check for tem = ap. */ | |
774 | if (va_list_ptr_read (&si, rhs, lhs)) | |
775 | continue; | |
776 | ||
777 | /* Check for the last insn in: | |
778 | tem1 = ap; | |
779 | tem2 = tem1 + CST; | |
780 | ap = tem2; | |
781 | sequence. */ | |
782 | else if (va_list_ptr_write (&si, lhs, rhs)) | |
783 | continue; | |
784 | ||
785 | else | |
786 | check_va_list_escapes (&si, lhs, rhs); | |
787 | } | |
788 | else | |
789 | { | |
790 | /* Check for ap[0].field = temp. */ | |
791 | if (va_list_counter_struct_op (&si, lhs, rhs, true)) | |
792 | continue; | |
793 | ||
794 | /* Check for temp = ap[0].field. */ | |
795 | else if (va_list_counter_struct_op (&si, rhs, lhs, false)) | |
796 | continue; | |
797 | ||
798 | /* Do any architecture specific checking. */ | |
799 | else if (targetm.stdarg_optimize_hook | |
ffa47ae0 | 800 | && targetm.stdarg_optimize_hook (&si, lhs, rhs)) |
a6c787e5 | 801 | continue; |
802 | } | |
803 | } | |
804 | ||
805 | /* All other uses of va_list are either va_copy (that is not handled | |
806 | in this optimization), taking address of va_list variable or | |
807 | passing va_list to other functions (in that case va_list might | |
808 | escape the function and therefore va_start needs to set it up | |
809 | fully), or some unexpected use of va_list. None of these should | |
810 | happen in a gimplified VA_ARG_EXPR. */ | |
811 | if (si.va_list_escapes | |
812 | || walk_tree (&stmt, find_va_list_reference, | |
813 | si.va_list_vars, NULL)) | |
814 | { | |
815 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
816 | { | |
817 | fputs ("va_list escapes in ", dump_file); | |
818 | print_generic_expr (dump_file, stmt, dump_flags); | |
819 | fputc ('\n', dump_file); | |
820 | } | |
821 | va_list_escapes = true; | |
822 | } | |
823 | } | |
824 | ||
825 | if (va_list_escapes) | |
826 | break; | |
827 | } | |
828 | ||
829 | if (! va_list_escapes | |
830 | && va_list_simple_ptr | |
831 | && ! bitmap_empty_p (si.va_list_escape_vars) | |
832 | && check_all_va_list_escapes (&si)) | |
833 | va_list_escapes = true; | |
834 | ||
835 | finish: | |
836 | if (va_list_escapes) | |
837 | { | |
838 | cfun->va_list_gpr_size = VA_LIST_MAX_GPR_SIZE; | |
839 | cfun->va_list_fpr_size = VA_LIST_MAX_FPR_SIZE; | |
840 | } | |
841 | BITMAP_FREE (si.va_list_vars); | |
842 | BITMAP_FREE (si.va_list_escape_vars); | |
843 | free (si.offsets); | |
844 | if (dump_file) | |
845 | { | |
846 | fprintf (dump_file, "%s: va_list escapes %d, needs to save ", | |
847 | funcname, (int) va_list_escapes); | |
848 | if (cfun->va_list_gpr_size >= VA_LIST_MAX_GPR_SIZE) | |
849 | fputs ("all", dump_file); | |
850 | else | |
851 | fprintf (dump_file, "%d", cfun->va_list_gpr_size); | |
852 | fputs (" GPR units and ", dump_file); | |
853 | if (cfun->va_list_fpr_size >= VA_LIST_MAX_FPR_SIZE) | |
854 | fputs ("all", dump_file); | |
855 | else | |
856 | fprintf (dump_file, "%d", cfun->va_list_fpr_size); | |
857 | fputs (" FPR units.\n", dump_file); | |
858 | } | |
859 | } | |
860 | ||
861 | ||
862 | struct tree_opt_pass pass_stdarg = | |
863 | { | |
864 | "stdarg", /* name */ | |
865 | gate_optimize_stdarg, /* gate */ | |
866 | execute_optimize_stdarg, /* execute */ | |
867 | NULL, /* sub */ | |
868 | NULL, /* next */ | |
869 | 0, /* static_pass_number */ | |
870 | 0, /* tv_id */ | |
871 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
872 | 0, /* properties_provided */ | |
873 | 0, /* properties_destroyed */ | |
874 | 0, /* todo_flags_start */ | |
875 | TODO_dump_func, /* todo_flags_finish */ | |
876 | 0 /* letter */ | |
877 | }; |