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a347af29 | 1 | /* Switch Conversion converts variable initializations based on switch |
2 | statements to initializations from a static array. | |
3 | Copyright (C) 2006, 2008 Free Software Foundation, Inc. | |
4 | Contributed by Martin Jambor <jamborm@suse.cz> | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by the | |
10 | Free Software Foundation; either version 3, or (at your option) any | |
11 | later version. | |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
14 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GCC; see the file COPYING3. If not, write to the Free | |
20 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA | |
21 | 02110-1301, USA. */ | |
22 | ||
23 | /* | |
24 | Switch initialization conversion | |
25 | ||
26 | The following pass changes simple initializations of scalars in a switch | |
27 | statement into initializations from a static array. Obviously, the values must | |
28 | be constant and known at compile time and a default branch must be | |
29 | provided. For example, the following code: | |
30 | ||
31 | int a,b; | |
32 | ||
33 | switch (argc) | |
34 | { | |
35 | case 1: | |
36 | case 2: | |
37 | a_1 = 8; | |
38 | b_1 = 6; | |
39 | break; | |
40 | case 3: | |
41 | a_2 = 9; | |
42 | b_2 = 5; | |
43 | break; | |
44 | case 12: | |
45 | a_3 = 10; | |
46 | b_3 = 4; | |
47 | break; | |
48 | default: | |
49 | a_4 = 16; | |
50 | b_4 = 1; | |
51 | } | |
52 | a_5 = PHI <a_1, a_2, a_3, a_4> | |
53 | b_5 = PHI <b_1, b_2, b_3, b_4> | |
54 | ||
55 | ||
56 | is changed into: | |
57 | ||
58 | static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4}; | |
59 | static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16, | |
60 | 16, 16, 10}; | |
61 | ||
62 | if (((unsigned) argc) - 1 < 11) | |
63 | { | |
64 | a_6 = CSWTCH02[argc - 1]; | |
65 | b_6 = CSWTCH01[argc - 1]; | |
66 | } | |
67 | else | |
68 | { | |
69 | a_7 = 16; | |
70 | b_7 = 1; | |
71 | } | |
72 | a_5 = PHI <a_6, a_7> | |
73 | b_b = PHI <b_6, b_7> | |
74 | ||
75 | There are further constraints. Specifically, the range of values across all | |
76 | case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default | |
77 | eight) times the number of the actual switch branches. */ | |
78 | ||
79 | #include "config.h" | |
80 | #include "system.h" | |
81 | #include "coretypes.h" | |
82 | #include "tm.h" | |
83 | #include <signal.h> | |
84 | ||
85 | #include "line-map.h" | |
86 | #include "params.h" | |
87 | #include "flags.h" | |
88 | #include "tree.h" | |
89 | #include "basic-block.h" | |
90 | #include "tree-flow.h" | |
91 | #include "tree-flow-inline.h" | |
92 | #include "tree-ssa-operands.h" | |
93 | #include "output.h" | |
94 | #include "input.h" | |
95 | #include "tree-pass.h" | |
96 | #include "diagnostic.h" | |
97 | #include "tree-dump.h" | |
e28b8a69 | 98 | #include "timevar.h" |
a347af29 | 99 | |
100 | /* The main structure of the pass. */ | |
101 | struct switch_conv_info | |
102 | { | |
103 | /* The expression used to decide the switch branch. (It is subsequently used | |
104 | as the index to the created array.) */ | |
105 | tree index_expr; | |
106 | ||
107 | /* The following integer constants store the minimum value covered by the | |
108 | cases. */ | |
109 | tree range_min; | |
110 | ||
cc17b19b | 111 | /* The difference between the above two numbers, i.e. The size of the array |
a347af29 | 112 | that would have to be created by the transformation. */ |
113 | tree range_size; | |
114 | ||
115 | /* Basic block that contains the actual SWITCH_EXPR. */ | |
116 | basic_block switch_bb; | |
117 | ||
118 | /* All branches of the switch statement must have a single successor stored in | |
119 | the following variable. */ | |
120 | basic_block final_bb; | |
121 | ||
122 | /* Number of phi nodes in the final bb (that we'll be replacing). */ | |
123 | int phi_count; | |
124 | ||
cc17b19b | 125 | /* Array of default values, in the same order as phi nodes. */ |
a347af29 | 126 | tree *default_values; |
127 | ||
128 | /* Constructors of new static arrays. */ | |
129 | VEC (constructor_elt, gc) **constructors; | |
130 | ||
131 | /* Array of ssa names that are initialized with a value from a new static | |
132 | array. */ | |
133 | tree *target_inbound_names; | |
134 | ||
135 | /* Array of ssa names that are initialized with the default value if the | |
136 | switch expression is out of range. */ | |
137 | tree *target_outbound_names; | |
138 | ||
139 | /* The probability of the default edge in the replaced switch. */ | |
140 | int default_prob; | |
141 | ||
142 | /* The count of the default edge in the replaced switch. */ | |
143 | gcov_type default_count; | |
144 | ||
145 | /* Combined count of all other (non-default) edges in the replaced switch. */ | |
146 | gcov_type other_count; | |
147 | ||
cc17b19b | 148 | /* The first load statement that loads a temporary from a new static array. |
149 | */ | |
75a70cf9 | 150 | gimple arr_ref_first; |
a347af29 | 151 | |
152 | /* The last load statement that loads a temporary from a new static array. */ | |
75a70cf9 | 153 | gimple arr_ref_last; |
a347af29 | 154 | |
155 | /* String reason why the case wasn't a good candidate that is written to the | |
156 | dump file, if there is one. */ | |
157 | const char *reason; | |
158 | }; | |
159 | ||
160 | /* Global pass info. */ | |
161 | static struct switch_conv_info info; | |
162 | ||
163 | ||
164 | /* Checks whether the range given by individual case statements of the SWTCH | |
165 | switch statement isn't too big and whether the number of branches actually | |
166 | satisfies the size of the new array. */ | |
167 | ||
168 | static bool | |
75a70cf9 | 169 | check_range (gimple swtch) |
a347af29 | 170 | { |
171 | tree min_case, max_case; | |
75a70cf9 | 172 | unsigned int branch_num = gimple_switch_num_labels (swtch); |
a347af29 | 173 | tree range_max; |
174 | ||
175 | /* The gimplifier has already sorted the cases by CASE_LOW and ensured there | |
176 | is a default label which is the last in the vector. */ | |
177 | ||
75a70cf9 | 178 | min_case = gimple_switch_label (swtch, 1); |
a347af29 | 179 | info.range_min = CASE_LOW (min_case); |
180 | ||
181 | gcc_assert (branch_num > 1); | |
75a70cf9 | 182 | gcc_assert (CASE_LOW (gimple_switch_label (swtch, 0)) == NULL_TREE); |
183 | max_case = gimple_switch_label (swtch, branch_num - 1); | |
a347af29 | 184 | if (CASE_HIGH (max_case) != NULL_TREE) |
185 | range_max = CASE_HIGH (max_case); | |
186 | else | |
187 | range_max = CASE_LOW (max_case); | |
188 | ||
189 | gcc_assert (info.range_min); | |
190 | gcc_assert (range_max); | |
191 | ||
192 | info.range_size = int_const_binop (MINUS_EXPR, range_max, info.range_min, 0); | |
193 | ||
194 | gcc_assert (info.range_size); | |
195 | if (!host_integerp (info.range_size, 1)) | |
196 | { | |
197 | info.reason = "index range way too large or otherwise unusable.\n"; | |
198 | return false; | |
199 | } | |
200 | ||
201 | if ((unsigned HOST_WIDE_INT) tree_low_cst (info.range_size, 1) | |
202 | > ((unsigned) branch_num * SWITCH_CONVERSION_BRANCH_RATIO)) | |
203 | { | |
204 | info.reason = "the maximum range-branch ratio exceeded.\n"; | |
205 | return false; | |
206 | } | |
207 | ||
208 | return true; | |
209 | } | |
210 | ||
211 | /* Checks the given CS switch case whether it is suitable for conversion | |
212 | (whether all but the default basic blocks are empty and so on). If it is, | |
213 | adds the case to the branch list along with values for the defined variables | |
214 | and returns true. Otherwise returns false. */ | |
215 | ||
216 | static bool | |
217 | check_process_case (tree cs) | |
218 | { | |
219 | tree ldecl; | |
220 | basic_block label_bb, following_bb; | |
221 | edge e; | |
222 | ||
223 | ldecl = CASE_LABEL (cs); | |
224 | label_bb = label_to_block (ldecl); | |
225 | ||
226 | e = find_edge (info.switch_bb, label_bb); | |
227 | gcc_assert (e); | |
228 | ||
229 | if (CASE_LOW (cs) == NULL_TREE) | |
230 | { | |
231 | /* Default branch. */ | |
232 | info.default_prob = e->probability; | |
233 | info.default_count = e->count; | |
234 | } | |
235 | else | |
236 | info.other_count += e->count; | |
237 | ||
238 | if (!label_bb) | |
239 | { | |
240 | info.reason = " Bad case - cs BB label is NULL\n"; | |
241 | return false; | |
242 | } | |
243 | ||
244 | if (!single_pred_p (label_bb)) | |
245 | { | |
246 | if (info.final_bb && info.final_bb != label_bb) | |
247 | { | |
248 | info.reason = " Bad case - a non-final BB has two predecessors\n"; | |
249 | return false; /* sth complex going on in this branch */ | |
250 | } | |
251 | ||
252 | following_bb = label_bb; | |
253 | } | |
254 | else | |
255 | { | |
256 | if (!empty_block_p (label_bb)) | |
257 | { | |
258 | info.reason = " Bad case - a non-final BB not empty\n"; | |
259 | return false; | |
260 | } | |
261 | ||
262 | e = single_succ_edge (label_bb); | |
263 | following_bb = single_succ (label_bb); | |
264 | } | |
265 | ||
266 | if (!info.final_bb) | |
267 | info.final_bb = following_bb; | |
268 | else if (info.final_bb != following_bb) | |
269 | { | |
270 | info.reason = " Bad case - different final BB\n"; | |
271 | return false; /* the only successor is not common for all the branches */ | |
272 | } | |
273 | ||
274 | return true; | |
275 | } | |
276 | ||
277 | /* This function checks whether all required values in phi nodes in final_bb | |
278 | are constants. Required values are those that correspond to a basic block | |
279 | which is a part of the examined switch statement. It returns true if the | |
280 | phi nodes are OK, otherwise false. */ | |
281 | ||
282 | static bool | |
283 | check_final_bb (void) | |
284 | { | |
75a70cf9 | 285 | gimple_stmt_iterator gsi; |
a347af29 | 286 | |
287 | info.phi_count = 0; | |
75a70cf9 | 288 | for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
a347af29 | 289 | { |
75a70cf9 | 290 | gimple phi = gsi_stmt (gsi); |
291 | unsigned int i; | |
a347af29 | 292 | |
293 | info.phi_count++; | |
294 | ||
75a70cf9 | 295 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
a347af29 | 296 | { |
75a70cf9 | 297 | basic_block bb = gimple_phi_arg_edge (phi, i)->src; |
a347af29 | 298 | |
54af7f7e | 299 | if (bb == info.switch_bb |
300 | || (single_pred_p (bb) && single_pred (bb) == info.switch_bb)) | |
a347af29 | 301 | { |
54af7f7e | 302 | tree reloc, val; |
303 | ||
304 | val = gimple_phi_arg_def (phi, i); | |
305 | if (!is_gimple_ip_invariant (val)) | |
306 | { | |
307 | info.reason = " Non-invariant value from a case\n"; | |
308 | return false; /* Non-invariant argument. */ | |
309 | } | |
310 | reloc = initializer_constant_valid_p (val, TREE_TYPE (val)); | |
311 | if ((flag_pic && reloc != null_pointer_node) | |
312 | || (!flag_pic && reloc == NULL_TREE)) | |
313 | { | |
314 | if (reloc) | |
315 | info.reason | |
316 | = " Value from a case would need runtime relocations\n"; | |
317 | else | |
318 | info.reason | |
319 | = " Value from a case is not a valid initializer\n"; | |
320 | return false; | |
321 | } | |
a347af29 | 322 | } |
323 | } | |
324 | } | |
325 | ||
326 | return true; | |
327 | } | |
328 | ||
329 | /* The following function allocates default_values, target_{in,out}_names and | |
330 | constructors arrays. The last one is also populated with pointers to | |
331 | vectors that will become constructors of new arrays. */ | |
332 | ||
333 | static void | |
334 | create_temp_arrays (void) | |
335 | { | |
336 | int i; | |
337 | ||
338 | info.default_values = (tree *) xcalloc (info.phi_count, sizeof (tree)); | |
339 | info.constructors = (VEC (constructor_elt, gc) **) xcalloc (info.phi_count, | |
340 | sizeof (tree)); | |
341 | info.target_inbound_names = (tree *) xcalloc (info.phi_count, sizeof (tree)); | |
342 | info.target_outbound_names = (tree *) xcalloc (info.phi_count, | |
343 | sizeof (tree)); | |
344 | ||
345 | for (i = 0; i < info.phi_count; i++) | |
75a70cf9 | 346 | info.constructors[i] |
347 | = VEC_alloc (constructor_elt, gc, tree_low_cst (info.range_size, 1) + 1); | |
a347af29 | 348 | } |
349 | ||
350 | /* Free the arrays created by create_temp_arrays(). The vectors that are | |
351 | created by that function are not freed here, however, because they have | |
352 | already become constructors and must be preserved. */ | |
353 | ||
354 | static void | |
355 | free_temp_arrays (void) | |
356 | { | |
357 | free (info.constructors); | |
358 | free (info.default_values); | |
359 | free (info.target_inbound_names); | |
360 | free (info.target_outbound_names); | |
361 | } | |
362 | ||
363 | /* Populate the array of default values in the order of phi nodes. | |
364 | DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch. */ | |
365 | ||
366 | static void | |
367 | gather_default_values (tree default_case) | |
368 | { | |
75a70cf9 | 369 | gimple_stmt_iterator gsi; |
a347af29 | 370 | basic_block bb = label_to_block (CASE_LABEL (default_case)); |
371 | edge e; | |
75a70cf9 | 372 | int i = 0; |
a347af29 | 373 | |
374 | gcc_assert (CASE_LOW (default_case) == NULL_TREE); | |
375 | ||
376 | if (bb == info.final_bb) | |
377 | e = find_edge (info.switch_bb, bb); | |
378 | else | |
379 | e = single_succ_edge (bb); | |
380 | ||
75a70cf9 | 381 | for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
a347af29 | 382 | { |
75a70cf9 | 383 | gimple phi = gsi_stmt (gsi); |
a347af29 | 384 | tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
385 | gcc_assert (val); | |
75a70cf9 | 386 | info.default_values[i++] = val; |
a347af29 | 387 | } |
388 | } | |
389 | ||
390 | /* The following function populates the vectors in the constructors array with | |
391 | future contents of the static arrays. The vectors are populated in the | |
392 | order of phi nodes. SWTCH is the switch statement being converted. */ | |
393 | ||
394 | static void | |
75a70cf9 | 395 | build_constructors (gimple swtch) |
a347af29 | 396 | { |
75a70cf9 | 397 | unsigned i, branch_num = gimple_switch_num_labels (swtch); |
a347af29 | 398 | tree pos = info.range_min; |
399 | ||
75a70cf9 | 400 | for (i = 1; i < branch_num; i++) |
a347af29 | 401 | { |
75a70cf9 | 402 | tree cs = gimple_switch_label (swtch, i); |
a347af29 | 403 | basic_block bb = label_to_block (CASE_LABEL (cs)); |
404 | edge e; | |
75a70cf9 | 405 | tree high; |
406 | gimple_stmt_iterator gsi; | |
a347af29 | 407 | int j; |
408 | ||
409 | if (bb == info.final_bb) | |
410 | e = find_edge (info.switch_bb, bb); | |
411 | else | |
412 | e = single_succ_edge (bb); | |
413 | gcc_assert (e); | |
414 | ||
415 | while (tree_int_cst_lt (pos, CASE_LOW (cs))) | |
416 | { | |
417 | int k; | |
418 | for (k = 0; k < info.phi_count; k++) | |
419 | { | |
420 | constructor_elt *elt; | |
421 | ||
422 | elt = VEC_quick_push (constructor_elt, | |
423 | info.constructors[k], NULL); | |
75a70cf9 | 424 | elt->index = int_const_binop (MINUS_EXPR, pos, |
425 | info.range_min, 0); | |
a347af29 | 426 | elt->value = info.default_values[k]; |
427 | } | |
428 | ||
429 | pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0); | |
430 | } | |
cc17b19b | 431 | gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs))); |
a347af29 | 432 | |
433 | j = 0; | |
434 | if (CASE_HIGH (cs)) | |
435 | high = CASE_HIGH (cs); | |
436 | else | |
cc17b19b | 437 | high = CASE_LOW (cs); |
75a70cf9 | 438 | for (gsi = gsi_start_phis (info.final_bb); |
439 | !gsi_end_p (gsi); gsi_next (&gsi)) | |
a347af29 | 440 | { |
75a70cf9 | 441 | gimple phi = gsi_stmt (gsi); |
a347af29 | 442 | tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
7558c999 | 443 | tree low = CASE_LOW (cs); |
a347af29 | 444 | pos = CASE_LOW (cs); |
445 | ||
48e1416a | 446 | do |
a347af29 | 447 | { |
448 | constructor_elt *elt; | |
449 | ||
450 | elt = VEC_quick_push (constructor_elt, | |
451 | info.constructors[j], NULL); | |
452 | elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min, 0); | |
453 | elt->value = val; | |
454 | ||
455 | pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0); | |
f6ac75a7 | 456 | } while (!tree_int_cst_lt (high, pos) |
457 | && tree_int_cst_lt (low, pos)); | |
a347af29 | 458 | j++; |
459 | } | |
460 | } | |
461 | } | |
462 | ||
f6ac75a7 | 463 | /* If all values in the constructor vector are the same, return the value. |
464 | Otherwise return NULL_TREE. Not supposed to be called for empty | |
465 | vectors. */ | |
466 | ||
467 | static tree | |
468 | constructor_contains_same_values_p (VEC (constructor_elt, gc) *vec) | |
469 | { | |
470 | int i, len = VEC_length (constructor_elt, vec); | |
471 | tree prev = NULL_TREE; | |
472 | ||
473 | for (i = 0; i < len; i++) | |
474 | { | |
475 | constructor_elt *elt = VEC_index (constructor_elt, vec, i); | |
48e1416a | 476 | |
f6ac75a7 | 477 | if (!prev) |
478 | prev = elt->value; | |
479 | else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST)) | |
480 | return NULL_TREE; | |
481 | } | |
482 | return prev; | |
483 | } | |
484 | ||
a347af29 | 485 | /* Create an appropriate array type and declaration and assemble a static array |
486 | variable. Also create a load statement that initializes the variable in | |
487 | question with a value from the static array. SWTCH is the switch statement | |
488 | being converted, NUM is the index to arrays of constructors, default values | |
489 | and target SSA names for this particular array. ARR_INDEX_TYPE is the type | |
490 | of the index of the new array, PHI is the phi node of the final BB that | |
491 | corresponds to the value that will be loaded from the created array. TIDX | |
f6ac75a7 | 492 | is an ssa name of a temporary variable holding the index for loads from the |
493 | new array. */ | |
a347af29 | 494 | |
495 | static void | |
75a70cf9 | 496 | build_one_array (gimple swtch, int num, tree arr_index_type, gimple phi, |
497 | tree tidx) | |
a347af29 | 498 | { |
f6ac75a7 | 499 | tree name, cst; |
75a70cf9 | 500 | gimple load; |
f6ac75a7 | 501 | gimple_stmt_iterator gsi = gsi_for_stmt (swtch); |
e60a6f7b | 502 | location_t loc = gimple_location (swtch); |
a347af29 | 503 | |
504 | gcc_assert (info.default_values[num]); | |
a347af29 | 505 | |
75a70cf9 | 506 | name = make_ssa_name (SSA_NAME_VAR (PHI_RESULT (phi)), NULL); |
a347af29 | 507 | info.target_inbound_names[num] = name; |
508 | ||
f6ac75a7 | 509 | cst = constructor_contains_same_values_p (info.constructors[num]); |
510 | if (cst) | |
511 | load = gimple_build_assign (name, cst); | |
512 | else | |
513 | { | |
514 | tree array_type, ctor, decl, value_type, fetch; | |
515 | ||
516 | value_type = TREE_TYPE (info.default_values[num]); | |
517 | array_type = build_array_type (value_type, arr_index_type); | |
518 | ctor = build_constructor (array_type, info.constructors[num]); | |
519 | TREE_CONSTANT (ctor) = true; | |
520 | ||
e60a6f7b | 521 | decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type); |
f6ac75a7 | 522 | TREE_STATIC (decl) = 1; |
523 | DECL_INITIAL (decl) = ctor; | |
524 | ||
525 | DECL_NAME (decl) = create_tmp_var_name ("CSWTCH"); | |
526 | DECL_ARTIFICIAL (decl) = 1; | |
527 | TREE_CONSTANT (decl) = 1; | |
528 | add_referenced_var (decl); | |
529 | varpool_mark_needed_node (varpool_node (decl)); | |
530 | varpool_finalize_decl (decl); | |
531 | ||
532 | fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE, | |
533 | NULL_TREE); | |
534 | load = gimple_build_assign (name, fetch); | |
535 | } | |
a347af29 | 536 | |
f6ac75a7 | 537 | SSA_NAME_DEF_STMT (name) = load; |
75a70cf9 | 538 | gsi_insert_before (&gsi, load, GSI_SAME_STMT); |
f6ac75a7 | 539 | update_stmt (load); |
a347af29 | 540 | info.arr_ref_last = load; |
a347af29 | 541 | } |
542 | ||
543 | /* Builds and initializes static arrays initialized with values gathered from | |
544 | the SWTCH switch statement. Also creates statements that load values from | |
545 | them. */ | |
546 | ||
547 | static void | |
75a70cf9 | 548 | build_arrays (gimple swtch) |
a347af29 | 549 | { |
550 | tree arr_index_type; | |
51836a0c | 551 | tree tidx, sub, tmp; |
75a70cf9 | 552 | gimple stmt; |
553 | gimple_stmt_iterator gsi; | |
a347af29 | 554 | int i; |
389dd41b | 555 | location_t loc = gimple_location (swtch); |
a347af29 | 556 | |
75a70cf9 | 557 | gsi = gsi_for_stmt (swtch); |
49a931ef | 558 | |
a347af29 | 559 | arr_index_type = build_index_type (info.range_size); |
42d9ffa5 | 560 | tmp = create_tmp_var (TREE_TYPE (info.index_expr), "csti"); |
51836a0c | 561 | add_referenced_var (tmp); |
562 | tidx = make_ssa_name (tmp, NULL); | |
389dd41b | 563 | sub = fold_build2_loc (loc, MINUS_EXPR, |
564 | TREE_TYPE (info.index_expr), info.index_expr, | |
565 | fold_convert_loc (loc, TREE_TYPE (info.index_expr), | |
566 | info.range_min)); | |
42d9ffa5 | 567 | sub = force_gimple_operand_gsi (&gsi, sub, |
75a70cf9 | 568 | false, NULL, true, GSI_SAME_STMT); |
569 | stmt = gimple_build_assign (tidx, sub); | |
f6ac75a7 | 570 | SSA_NAME_DEF_STMT (tidx) = stmt; |
a347af29 | 571 | |
75a70cf9 | 572 | gsi_insert_before (&gsi, stmt, GSI_SAME_STMT); |
f6ac75a7 | 573 | update_stmt (stmt); |
75a70cf9 | 574 | info.arr_ref_first = stmt; |
a347af29 | 575 | |
75a70cf9 | 576 | for (gsi = gsi_start_phis (info.final_bb), i = 0; |
577 | !gsi_end_p (gsi); gsi_next (&gsi), i++) | |
578 | build_one_array (swtch, i, arr_index_type, gsi_stmt (gsi), tidx); | |
a347af29 | 579 | } |
580 | ||
581 | /* Generates and appropriately inserts loads of default values at the position | |
582 | given by BSI. Returns the last inserted statement. */ | |
583 | ||
75a70cf9 | 584 | static gimple |
585 | gen_def_assigns (gimple_stmt_iterator *gsi) | |
a347af29 | 586 | { |
587 | int i; | |
75a70cf9 | 588 | gimple assign = NULL; |
a347af29 | 589 | |
590 | for (i = 0; i < info.phi_count; i++) | |
591 | { | |
75a70cf9 | 592 | tree name |
593 | = make_ssa_name (SSA_NAME_VAR (info.target_inbound_names[i]), NULL); | |
a347af29 | 594 | |
595 | info.target_outbound_names[i] = name; | |
75a70cf9 | 596 | assign = gimple_build_assign (name, info.default_values[i]); |
a347af29 | 597 | SSA_NAME_DEF_STMT (name) = assign; |
75a70cf9 | 598 | gsi_insert_before (gsi, assign, GSI_SAME_STMT); |
f6ac75a7 | 599 | update_stmt (assign); |
a347af29 | 600 | } |
601 | return assign; | |
602 | } | |
603 | ||
604 | /* Deletes the unused bbs and edges that now contain the switch statement and | |
605 | its empty branch bbs. BBD is the now dead BB containing the original switch | |
606 | statement, FINAL is the last BB of the converted switch statement (in terms | |
607 | of succession). */ | |
608 | ||
609 | static void | |
610 | prune_bbs (basic_block bbd, basic_block final) | |
611 | { | |
612 | edge_iterator ei; | |
613 | edge e; | |
614 | ||
615 | for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); ) | |
616 | { | |
617 | basic_block bb; | |
618 | bb = e->dest; | |
619 | remove_edge (e); | |
620 | if (bb != final) | |
621 | delete_basic_block (bb); | |
622 | } | |
623 | delete_basic_block (bbd); | |
624 | } | |
625 | ||
626 | /* Add values to phi nodes in final_bb for the two new edges. E1F is the edge | |
627 | from the basic block loading values from an array and E2F from the basic | |
628 | block loading default values. BBF is the last switch basic block (see the | |
629 | bbf description in the comment below). */ | |
630 | ||
631 | static void | |
632 | fix_phi_nodes (edge e1f, edge e2f, basic_block bbf) | |
633 | { | |
75a70cf9 | 634 | gimple_stmt_iterator gsi; |
a347af29 | 635 | int i; |
636 | ||
75a70cf9 | 637 | for (gsi = gsi_start_phis (bbf), i = 0; |
638 | !gsi_end_p (gsi); gsi_next (&gsi), i++) | |
a347af29 | 639 | { |
75a70cf9 | 640 | gimple phi = gsi_stmt (gsi); |
efbcb6de | 641 | add_phi_arg (phi, info.target_inbound_names[i], e1f, UNKNOWN_LOCATION); |
642 | add_phi_arg (phi, info.target_outbound_names[i], e2f, UNKNOWN_LOCATION); | |
a347af29 | 643 | } |
644 | ||
645 | } | |
646 | ||
647 | /* Creates a check whether the switch expression value actually falls into the | |
648 | range given by all the cases. If it does not, the temporaries are loaded | |
649 | with default values instead. SWTCH is the switch statement being converted. | |
650 | ||
651 | bb0 is the bb with the switch statement, however, we'll end it with a | |
652 | condition instead. | |
653 | ||
654 | bb1 is the bb to be used when the range check went ok. It is derived from | |
655 | the switch BB | |
656 | ||
657 | bb2 is the bb taken when the expression evaluated outside of the range | |
658 | covered by the created arrays. It is populated by loads of default | |
659 | values. | |
660 | ||
661 | bbF is a fall through for both bb1 and bb2 and contains exactly what | |
662 | originally followed the switch statement. | |
663 | ||
664 | bbD contains the switch statement (in the end). It is unreachable but we | |
665 | still need to strip off its edges. | |
666 | */ | |
667 | ||
668 | static void | |
75a70cf9 | 669 | gen_inbound_check (gimple swtch) |
a347af29 | 670 | { |
e60a6f7b | 671 | tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION); |
672 | tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION); | |
673 | tree label_decl3 = create_artificial_label (UNKNOWN_LOCATION); | |
75a70cf9 | 674 | gimple label1, label2, label3; |
a347af29 | 675 | |
1763aab8 | 676 | tree utype; |
f6ac75a7 | 677 | tree tmp_u_1, tmp_u_2, tmp_u_var; |
75a70cf9 | 678 | tree cast; |
679 | gimple cast_assign, minus_assign; | |
680 | tree ulb, minus; | |
a347af29 | 681 | tree bound; |
682 | ||
75a70cf9 | 683 | gimple cond_stmt; |
a347af29 | 684 | |
75a70cf9 | 685 | gimple last_assign; |
686 | gimple_stmt_iterator gsi; | |
a347af29 | 687 | basic_block bb0, bb1, bb2, bbf, bbd; |
688 | edge e01, e02, e21, e1d, e1f, e2f; | |
389dd41b | 689 | location_t loc = gimple_location (swtch); |
a347af29 | 690 | |
691 | gcc_assert (info.default_values); | |
75a70cf9 | 692 | bb0 = gimple_bb (swtch); |
a347af29 | 693 | |
1763aab8 | 694 | /* Make sure we do not generate arithmetics in a subrange. */ |
695 | if (TREE_TYPE (TREE_TYPE (info.index_expr))) | |
696 | utype = unsigned_type_for (TREE_TYPE (TREE_TYPE (info.index_expr))); | |
697 | else | |
698 | utype = unsigned_type_for (TREE_TYPE (info.index_expr)); | |
699 | ||
a347af29 | 700 | /* (end of) block 0 */ |
75a70cf9 | 701 | gsi = gsi_for_stmt (info.arr_ref_first); |
f6ac75a7 | 702 | tmp_u_var = create_tmp_var (utype, "csui"); |
51836a0c | 703 | add_referenced_var (tmp_u_var); |
f6ac75a7 | 704 | tmp_u_1 = make_ssa_name (tmp_u_var, NULL); |
a347af29 | 705 | |
389dd41b | 706 | cast = fold_convert_loc (loc, utype, info.index_expr); |
f6ac75a7 | 707 | cast_assign = gimple_build_assign (tmp_u_1, cast); |
708 | SSA_NAME_DEF_STMT (tmp_u_1) = cast_assign; | |
75a70cf9 | 709 | gsi_insert_before (&gsi, cast_assign, GSI_SAME_STMT); |
f6ac75a7 | 710 | update_stmt (cast_assign); |
a347af29 | 711 | |
389dd41b | 712 | ulb = fold_convert_loc (loc, utype, info.range_min); |
713 | minus = fold_build2_loc (loc, MINUS_EXPR, utype, tmp_u_1, ulb); | |
75a70cf9 | 714 | minus = force_gimple_operand_gsi (&gsi, minus, false, NULL, true, |
715 | GSI_SAME_STMT); | |
f6ac75a7 | 716 | tmp_u_2 = make_ssa_name (tmp_u_var, NULL); |
717 | minus_assign = gimple_build_assign (tmp_u_2, minus); | |
718 | SSA_NAME_DEF_STMT (tmp_u_2) = minus_assign; | |
75a70cf9 | 719 | gsi_insert_before (&gsi, minus_assign, GSI_SAME_STMT); |
f6ac75a7 | 720 | update_stmt (minus_assign); |
a347af29 | 721 | |
389dd41b | 722 | bound = fold_convert_loc (loc, utype, info.range_size); |
f6ac75a7 | 723 | cond_stmt = gimple_build_cond (LE_EXPR, tmp_u_2, bound, NULL_TREE, NULL_TREE); |
75a70cf9 | 724 | gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT); |
f6ac75a7 | 725 | update_stmt (cond_stmt); |
a347af29 | 726 | |
727 | /* block 2 */ | |
75a70cf9 | 728 | gsi = gsi_for_stmt (info.arr_ref_first); |
729 | label2 = gimple_build_label (label_decl2); | |
730 | gsi_insert_before (&gsi, label2, GSI_SAME_STMT); | |
731 | last_assign = gen_def_assigns (&gsi); | |
a347af29 | 732 | |
733 | /* block 1 */ | |
75a70cf9 | 734 | gsi = gsi_for_stmt (info.arr_ref_first); |
735 | label1 = gimple_build_label (label_decl1); | |
736 | gsi_insert_before (&gsi, label1, GSI_SAME_STMT); | |
a347af29 | 737 | |
738 | /* block F */ | |
75a70cf9 | 739 | gsi = gsi_start_bb (info.final_bb); |
740 | label3 = gimple_build_label (label_decl3); | |
741 | gsi_insert_before (&gsi, label3, GSI_SAME_STMT); | |
a347af29 | 742 | |
743 | /* cfg fix */ | |
75a70cf9 | 744 | e02 = split_block (bb0, cond_stmt); |
a347af29 | 745 | bb2 = e02->dest; |
746 | ||
747 | e21 = split_block (bb2, last_assign); | |
748 | bb1 = e21->dest; | |
749 | remove_edge (e21); | |
750 | ||
751 | e1d = split_block (bb1, info.arr_ref_last); | |
752 | bbd = e1d->dest; | |
753 | remove_edge (e1d); | |
754 | ||
755 | /* flags and profiles of the edge for in-range values */ | |
756 | e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE); | |
757 | e01->probability = REG_BR_PROB_BASE - info.default_prob; | |
758 | e01->count = info.other_count; | |
759 | ||
760 | /* flags and profiles of the edge taking care of out-of-range values */ | |
761 | e02->flags &= ~EDGE_FALLTHRU; | |
762 | e02->flags |= EDGE_FALSE_VALUE; | |
763 | e02->probability = info.default_prob; | |
764 | e02->count = info.default_count; | |
765 | ||
766 | bbf = info.final_bb; | |
767 | ||
768 | e1f = make_edge (bb1, bbf, EDGE_FALLTHRU); | |
769 | e1f->probability = REG_BR_PROB_BASE; | |
770 | e1f->count = info.other_count; | |
771 | ||
772 | e2f = make_edge (bb2, bbf, EDGE_FALLTHRU); | |
773 | e2f->probability = REG_BR_PROB_BASE; | |
774 | e2f->count = info.default_count; | |
775 | ||
776 | /* frequencies of the new BBs */ | |
777 | bb1->frequency = EDGE_FREQUENCY (e01); | |
778 | bb2->frequency = EDGE_FREQUENCY (e02); | |
779 | bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f); | |
780 | ||
75a70cf9 | 781 | prune_bbs (bbd, info.final_bb); /* To keep calc_dfs_tree() in dominance.c |
782 | happy. */ | |
a347af29 | 783 | |
784 | fix_phi_nodes (e1f, e2f, bbf); | |
785 | ||
786 | free_dominance_info (CDI_DOMINATORS); | |
787 | free_dominance_info (CDI_POST_DOMINATORS); | |
788 | } | |
789 | ||
790 | /* The following function is invoked on every switch statement (the current one | |
791 | is given in SWTCH) and runs the individual phases of switch conversion on it | |
792 | one after another until one fails or the conversion is completed. */ | |
793 | ||
794 | static bool | |
75a70cf9 | 795 | process_switch (gimple swtch) |
a347af29 | 796 | { |
75a70cf9 | 797 | unsigned int i, branch_num = gimple_switch_num_labels (swtch); |
a347af29 | 798 | tree index_type; |
799 | ||
800 | /* Operand 2 is either NULL_TREE or a vector of cases (stmt.c). */ | |
75a70cf9 | 801 | if (branch_num < 2) |
a347af29 | 802 | { |
75a70cf9 | 803 | info.reason = "switch has no labels\n"; |
a347af29 | 804 | return false; |
805 | } | |
806 | ||
a347af29 | 807 | info.final_bb = NULL; |
75a70cf9 | 808 | info.switch_bb = gimple_bb (swtch); |
809 | info.index_expr = gimple_switch_index (swtch); | |
a347af29 | 810 | index_type = TREE_TYPE (info.index_expr); |
75a70cf9 | 811 | info.arr_ref_first = NULL; |
812 | info.arr_ref_last = NULL; | |
a347af29 | 813 | info.default_prob = 0; |
814 | info.default_count = 0; | |
815 | info.other_count = 0; | |
816 | ||
817 | /* An ERROR_MARK occurs for various reasons including invalid data type. | |
818 | (comment from stmt.c) */ | |
819 | if (index_type == error_mark_node) | |
820 | { | |
821 | info.reason = "index error.\n"; | |
822 | return false; | |
823 | } | |
824 | ||
825 | /* Check the case label values are within reasonable range: */ | |
826 | if (!check_range (swtch)) | |
827 | return false; | |
828 | ||
829 | /* For all the cases, see whether they are empty, the assignments they | |
830 | represent constant and so on... */ | |
75a70cf9 | 831 | for (i = 0; i < branch_num; i++) |
832 | if (!check_process_case (gimple_switch_label (swtch, i))) | |
833 | { | |
834 | if (dump_file) | |
835 | fprintf (dump_file, "Processing of case %i failed\n", i); | |
836 | return false; | |
837 | } | |
a347af29 | 838 | |
839 | if (!check_final_bb ()) | |
840 | return false; | |
841 | ||
842 | /* At this point all checks have passed and we can proceed with the | |
843 | transformation. */ | |
844 | ||
845 | create_temp_arrays (); | |
75a70cf9 | 846 | gather_default_values (gimple_switch_label (swtch, 0)); |
a347af29 | 847 | build_constructors (swtch); |
848 | ||
849 | build_arrays (swtch); /* Build the static arrays and assignments. */ | |
cc17b19b | 850 | gen_inbound_check (swtch); /* Build the bounds check. */ |
a347af29 | 851 | |
852 | /* Cleanup: */ | |
853 | free_temp_arrays (); | |
854 | return true; | |
855 | } | |
856 | ||
857 | /* The main function of the pass scans statements for switches and invokes | |
858 | process_switch on them. */ | |
859 | ||
860 | static unsigned int | |
861 | do_switchconv (void) | |
862 | { | |
863 | basic_block bb; | |
864 | ||
865 | FOR_EACH_BB (bb) | |
866 | { | |
75a70cf9 | 867 | gimple stmt = last_stmt (bb); |
868 | if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) | |
a347af29 | 869 | { |
a347af29 | 870 | if (dump_file) |
871 | { | |
75a70cf9 | 872 | expanded_location loc = expand_location (gimple_location (stmt)); |
873 | ||
a347af29 | 874 | fprintf (dump_file, "beginning to process the following " |
875 | "SWITCH statement (%s:%d) : ------- \n", | |
876 | loc.file, loc.line); | |
75a70cf9 | 877 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
609e7ca1 | 878 | putc ('\n', dump_file); |
a347af29 | 879 | } |
880 | ||
881 | info.reason = NULL; | |
882 | if (process_switch (stmt)) | |
883 | { | |
884 | if (dump_file) | |
885 | { | |
609e7ca1 | 886 | fputs ("Switch converted\n", dump_file); |
887 | fputs ("--------------------------------\n", dump_file); | |
a347af29 | 888 | } |
889 | } | |
890 | else | |
891 | { | |
892 | if (dump_file) | |
893 | { | |
894 | gcc_assert (info.reason); | |
609e7ca1 | 895 | fputs ("Bailing out - ", dump_file); |
896 | fputs (info.reason, dump_file); | |
897 | fputs ("--------------------------------\n", dump_file); | |
a347af29 | 898 | } |
899 | } | |
900 | } | |
901 | } | |
902 | ||
903 | return 0; | |
904 | } | |
905 | ||
906 | /* The pass gate. */ | |
907 | ||
908 | static bool | |
909 | switchconv_gate (void) | |
910 | { | |
911 | return flag_tree_switch_conversion != 0; | |
912 | } | |
913 | ||
914 | struct gimple_opt_pass pass_convert_switch = | |
915 | { | |
916 | { | |
917 | GIMPLE_PASS, | |
918 | "switchconv", /* name */ | |
cc17b19b | 919 | switchconv_gate, /* gate */ |
a347af29 | 920 | do_switchconv, /* execute */ |
921 | NULL, /* sub */ | |
922 | NULL, /* next */ | |
923 | 0, /* static_pass_number */ | |
f28b0a6a | 924 | TV_TREE_SWITCH_CONVERSION, /* tv_id */ |
a347af29 | 925 | PROP_cfg | PROP_ssa, /* properties_required */ |
926 | 0, /* properties_provided */ | |
927 | 0, /* properties_destroyed */ | |
928 | 0, /* todo_flags_start */ | |
929 | TODO_update_ssa | TODO_dump_func | |
930 | | TODO_ggc_collect | TODO_verify_ssa /* todo_flags_finish */ | |
931 | } | |
932 | }; |