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242229bb JH |
1 | /* A pass for lowering trees to RTL. |
2 | Copyright (C) 2004 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GCC. | |
5 | ||
6 | GCC 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 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GCC 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 GCC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
25 | #include "tree.h" | |
26 | #include "rtl.h" | |
27 | #include "tm_p.h" | |
28 | #include "basic-block.h" | |
29 | #include "function.h" | |
30 | #include "expr.h" | |
31 | #include "langhooks.h" | |
32 | #include "tree-flow.h" | |
33 | #include "timevar.h" | |
34 | #include "tree-dump.h" | |
35 | #include "tree-pass.h" | |
36 | #include "except.h" | |
37 | #include "flags.h" | |
38 | /* Expand basic block BB from GIMPLE trees to RTL. */ | |
39 | ||
40 | static basic_block | |
41 | expand_block (basic_block bb, FILE * dump_file) | |
42 | { | |
43 | block_stmt_iterator bsi = bsi_start (bb); | |
44 | tree stmt = NULL; | |
45 | rtx note, last; | |
46 | edge e; | |
47 | ||
48 | if (dump_file) | |
49 | { | |
50 | tree_register_cfg_hooks (); | |
51 | dump_bb (bb, dump_file, 0); | |
52 | rtl_register_cfg_hooks (); | |
53 | } | |
54 | ||
55 | if (!bsi_end_p (bsi)) | |
56 | stmt = bsi_stmt (bsi); | |
57 | ||
58 | if (stmt && TREE_CODE (stmt) == LABEL_EXPR) | |
59 | { | |
60 | last = get_last_insn (); | |
61 | ||
62 | expand_expr_stmt_value (stmt, 0, 0); | |
63 | ||
64 | /* Java emits line number notes in the top of labels. | |
65 | ??? Make this go away once line number notes are obsoleted. */ | |
66 | BB_HEAD (bb) = NEXT_INSN (last); | |
67 | if (GET_CODE (BB_HEAD (bb)) == NOTE) | |
68 | BB_HEAD (bb) = NEXT_INSN (BB_HEAD (bb)); | |
69 | bsi_next (&bsi); | |
70 | note = emit_note_after (NOTE_INSN_BASIC_BLOCK, BB_HEAD (bb)); | |
71 | } | |
72 | else | |
73 | note = BB_HEAD (bb) = emit_note (NOTE_INSN_BASIC_BLOCK); | |
74 | ||
75 | NOTE_BASIC_BLOCK (note) = bb; | |
76 | ||
77 | e = bb->succ; | |
78 | while (e) | |
79 | { | |
80 | edge next = e->succ_next; | |
81 | ||
82 | /* Clear EDGE_EXECUTABLE. This flag is never used in the backend. */ | |
83 | e->flags &= ~EDGE_EXECUTABLE; | |
84 | ||
85 | /* At the moment not all abnormal edges match the RTL representation. | |
86 | It is safe to remove them here as find_sub_basic_blocks will | |
87 | rediscover them. In the future we should get this fixed properly. */ | |
88 | if (e->flags & EDGE_ABNORMAL) | |
89 | remove_edge (e); | |
90 | ||
91 | e = next; | |
92 | } | |
93 | ||
94 | for (; !bsi_end_p (bsi); bsi_next (&bsi)) | |
95 | { | |
96 | tree stmt = bsi_stmt (bsi); | |
97 | ||
98 | last = get_last_insn (); | |
99 | ||
100 | if (!stmt) | |
101 | continue; | |
102 | ||
103 | /* Expand this statement, then evaluate the resulting RTL and | |
104 | fixup the CFG accordingly. */ | |
105 | switch (TREE_CODE (stmt)) | |
106 | { | |
107 | case COND_EXPR: | |
108 | { | |
109 | basic_block new_bb, dest; | |
110 | edge new_edge; | |
111 | edge true_edge; | |
112 | edge false_edge; | |
113 | tree pred = COND_EXPR_COND (stmt); | |
114 | tree then_exp = COND_EXPR_THEN (stmt); | |
115 | tree else_exp = COND_EXPR_ELSE (stmt); | |
116 | rtx last = get_last_insn (); | |
117 | ||
118 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
119 | if (EXPR_LOCUS (stmt)) | |
120 | { | |
121 | emit_line_note (*(EXPR_LOCUS (stmt))); | |
122 | if (cfun->dont_emit_block_notes) | |
123 | record_block_change (TREE_BLOCK (stmt)); | |
124 | } | |
125 | ||
126 | /* These flags have no purpose in RTL land. */ | |
127 | true_edge->flags &= ~EDGE_TRUE_VALUE; | |
128 | false_edge->flags &= ~EDGE_FALSE_VALUE; | |
129 | ||
130 | /* We can either have a pure conditional jump with one fallthru | |
131 | edge or two-way jump that needs to be decomposed into two | |
132 | basic blocks. */ | |
133 | if (TREE_CODE (then_exp) == GOTO_EXPR | |
134 | && TREE_CODE (else_exp) == NOP_EXPR) | |
135 | { | |
136 | jumpif (pred, label_rtx (GOTO_DESTINATION (then_exp))); | |
137 | break; | |
138 | } | |
139 | if (TREE_CODE (else_exp) == GOTO_EXPR | |
140 | && TREE_CODE (then_exp) == NOP_EXPR) | |
141 | { | |
142 | jumpifnot (pred, label_rtx (GOTO_DESTINATION (else_exp))); | |
143 | break; | |
144 | } | |
145 | if (TREE_CODE (then_exp) != GOTO_EXPR | |
146 | || TREE_CODE (else_exp) != GOTO_EXPR) | |
147 | abort (); | |
148 | ||
149 | jumpif (pred, label_rtx (GOTO_DESTINATION (then_exp))); | |
150 | last = get_last_insn (); | |
151 | expand_expr (else_exp, const0_rtx, VOIDmode, 0); | |
152 | ||
153 | BB_END (bb) = last; | |
154 | if (GET_CODE (BB_END (bb)) == BARRIER) | |
155 | BB_END (bb) = PREV_INSN (BB_END (bb)); | |
156 | update_bb_for_insn (bb); | |
157 | ||
158 | new_bb = create_basic_block (NEXT_INSN (last), get_last_insn (), bb); | |
159 | dest = false_edge->dest; | |
160 | redirect_edge_succ (false_edge, new_bb); | |
161 | false_edge->flags |= EDGE_FALLTHRU; | |
162 | new_bb->count = false_edge->count; | |
163 | new_bb->frequency = EDGE_FREQUENCY (false_edge); | |
164 | new_edge = make_edge (new_bb, dest, 0); | |
165 | new_edge->probability = REG_BR_PROB_BASE; | |
166 | new_edge->count = new_bb->count; | |
167 | if (GET_CODE (BB_END (new_bb)) == BARRIER) | |
168 | BB_END (new_bb) = PREV_INSN (BB_END (new_bb)); | |
169 | update_bb_for_insn (new_bb); | |
170 | ||
171 | if (dump_file) | |
172 | { | |
173 | dump_bb (bb, dump_file, 0); | |
174 | dump_bb (new_bb, dump_file, 0); | |
175 | } | |
176 | return new_bb; | |
177 | } | |
178 | ||
179 | /* Update after expansion of sibling call. */ | |
180 | case CALL_EXPR: | |
181 | case MODIFY_EXPR: | |
182 | case RETURN_EXPR: | |
183 | expand_expr_stmt_value (stmt, 0, 0); | |
184 | for (last = NEXT_INSN (last); last; last = NEXT_INSN (last)) | |
185 | { | |
186 | if (GET_CODE (last) == CALL_INSN && SIBLING_CALL_P (last)) | |
187 | { | |
188 | edge e; | |
189 | int probability = 0; | |
190 | gcov_type count = 0; | |
191 | ||
192 | do_pending_stack_adjust (); | |
193 | e = bb->succ; | |
194 | while (e) | |
195 | { | |
196 | edge next = e->succ_next; | |
197 | ||
198 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH))) | |
199 | { | |
200 | if (e->dest != EXIT_BLOCK_PTR) | |
201 | { | |
202 | e->dest->count -= e->count; | |
203 | e->dest->frequency -= EDGE_FREQUENCY (e); | |
204 | if (e->dest->count < 0) | |
205 | e->dest->count = 0; | |
206 | if (e->dest->frequency < 0) | |
207 | e->dest->frequency = 0; | |
208 | } | |
209 | count += e->count; | |
210 | probability += e->probability; | |
211 | remove_edge (e); | |
212 | } | |
213 | ||
214 | e = next; | |
215 | } | |
216 | ||
217 | /* This is somewhat ugly: the call_expr expander often emits instructions | |
218 | after the sibcall (to perform the function return). These confuse the | |
219 | find_sub_basic_blocks code, so we need to get rid of these. */ | |
220 | last = NEXT_INSN (last); | |
221 | if (GET_CODE (last) != BARRIER) | |
222 | abort (); | |
223 | while (NEXT_INSN (last)) | |
224 | { | |
225 | /* For instance an sqrt builtin expander expands if with | |
226 | sibcall in the then and label for `else`. */ | |
227 | if (GET_CODE (NEXT_INSN (last)) == CODE_LABEL) | |
228 | break; | |
229 | delete_insn (NEXT_INSN (last)); | |
230 | } | |
231 | e = make_edge (bb, EXIT_BLOCK_PTR, | |
232 | EDGE_ABNORMAL | EDGE_SIBCALL); | |
233 | e->probability += probability; | |
234 | e->count += count; | |
235 | BB_END (bb) = last; | |
236 | update_bb_for_insn (bb); | |
237 | if (NEXT_INSN (last)) | |
238 | bb = create_basic_block (NEXT_INSN (last), get_last_insn (), bb); | |
239 | else | |
240 | return bb; | |
241 | } | |
242 | } | |
243 | break; | |
244 | ||
245 | default: | |
246 | expand_expr_stmt_value (stmt, 0, 0); | |
247 | break; | |
248 | } | |
249 | } | |
250 | ||
251 | do_pending_stack_adjust (); | |
252 | ||
253 | /* Find the the block tail. The last insn is the block is the insn | |
254 | before a barrier and/or table jump insn. */ | |
255 | last = get_last_insn (); | |
256 | if (GET_CODE (last) == BARRIER) | |
257 | last = PREV_INSN (last); | |
258 | if (JUMP_TABLE_DATA_P (last)) | |
259 | last = PREV_INSN (PREV_INSN (last)); | |
260 | BB_END (bb) = last; | |
261 | ||
262 | if (dump_file) | |
263 | dump_bb (bb, dump_file, 0); | |
264 | update_bb_for_insn (bb); | |
265 | return bb; | |
266 | } | |
267 | ||
268 | ||
269 | /* Create a basic block for initialization code. */ | |
270 | ||
271 | static basic_block | |
272 | construct_init_block (void) | |
273 | { | |
274 | basic_block init_block, first_block; | |
275 | edge e; | |
276 | ||
277 | expand_start_bindings_and_block (0, NULL_TREE); | |
278 | ||
279 | for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) | |
280 | if (e->dest == ENTRY_BLOCK_PTR->next_bb) | |
281 | break; | |
282 | ||
283 | init_block = create_basic_block (NEXT_INSN (get_insns ()), | |
284 | get_last_insn (), | |
285 | ENTRY_BLOCK_PTR); | |
286 | init_block->frequency = ENTRY_BLOCK_PTR->frequency; | |
287 | init_block->count = ENTRY_BLOCK_PTR->count; | |
288 | if (e) | |
289 | { | |
290 | first_block = e->dest; | |
291 | redirect_edge_succ (e, init_block); | |
292 | e = make_edge (init_block, first_block, EDGE_FALLTHRU); | |
293 | } | |
294 | else | |
295 | e = make_edge (init_block, EXIT_BLOCK_PTR, EDGE_FALLTHRU); | |
296 | e->probability = REG_BR_PROB_BASE; | |
297 | e->count = ENTRY_BLOCK_PTR->count; | |
298 | ||
299 | update_bb_for_insn (init_block); | |
300 | return init_block; | |
301 | } | |
302 | ||
303 | ||
304 | /* Create a block containing landing pads and similar stuff. */ | |
305 | ||
306 | static void | |
307 | construct_exit_block (void) | |
308 | { | |
309 | rtx head = get_last_insn (); | |
310 | rtx end; | |
311 | basic_block exit_block; | |
312 | edge e, e2, next; | |
313 | ||
314 | /* We hard-wired immediate_size_expand to zero above. | |
315 | expand_function_end will decrement this variable. So, we set the | |
316 | variable to one here, so that after the decrement it will remain | |
317 | zero. */ | |
318 | immediate_size_expand = 1; | |
319 | ||
320 | /* Make sure the locus is set to the end of the function, so that | |
321 | epilogue line numbers and warnings are set properly. */ | |
322 | if (cfun->function_end_locus.file) | |
323 | input_location = cfun->function_end_locus; | |
324 | ||
325 | /* The following insns belong to the top scope. */ | |
326 | record_block_change (DECL_INITIAL (current_function_decl)); | |
327 | ||
328 | expand_end_bindings (NULL_TREE, 1, 0); | |
329 | ||
330 | /* Generate rtl for function exit. */ | |
331 | expand_function_end (); | |
332 | ||
333 | end = get_last_insn (); | |
334 | if (head == end) | |
335 | return; | |
336 | while (NEXT_INSN (head) && GET_CODE (NEXT_INSN (head)) == NOTE) | |
337 | head = NEXT_INSN (head); | |
338 | exit_block = create_basic_block (NEXT_INSN (head), end, EXIT_BLOCK_PTR->prev_bb); | |
339 | exit_block->frequency = EXIT_BLOCK_PTR->frequency; | |
340 | exit_block->count = EXIT_BLOCK_PTR->count; | |
341 | for (e = EXIT_BLOCK_PTR->pred; e; e = next) | |
342 | { | |
343 | next = e->pred_next; | |
344 | if (!(e->flags & EDGE_ABNORMAL)) | |
345 | redirect_edge_succ (e, exit_block); | |
346 | } | |
347 | e = make_edge (exit_block, EXIT_BLOCK_PTR, EDGE_FALLTHRU); | |
348 | e->probability = REG_BR_PROB_BASE; | |
349 | e->count = EXIT_BLOCK_PTR->count; | |
350 | for (e2 = EXIT_BLOCK_PTR->pred; e2; e2 = e2->pred_next) | |
351 | if (e2 != e) | |
352 | { | |
353 | e->count -= e2->count; | |
354 | exit_block->count -= e2->count; | |
355 | exit_block->frequency -= EDGE_FREQUENCY (e2); | |
356 | } | |
357 | if (e->count < 0) | |
358 | e->count = 0; | |
359 | if (exit_block->count < 0) | |
360 | exit_block->count = 0; | |
361 | if (exit_block->frequency < 0) | |
362 | exit_block->frequency = 0; | |
363 | update_bb_for_insn (exit_block); | |
364 | } | |
365 | ||
366 | /* Called to move the SAVE_EXPRs for parameter declarations in a | |
367 | nested function into the nested function. DATA is really the | |
368 | nested FUNCTION_DECL. */ | |
369 | ||
370 | static tree | |
371 | set_save_expr_context (tree *tp, | |
372 | int *walk_subtrees, | |
373 | void *data) | |
374 | { | |
375 | if (TREE_CODE (*tp) == SAVE_EXPR && !SAVE_EXPR_CONTEXT (*tp)) | |
376 | SAVE_EXPR_CONTEXT (*tp) = (tree) data; | |
377 | /* Do not walk back into the SAVE_EXPR_CONTEXT; that will cause | |
378 | circularity. */ | |
379 | else if (DECL_P (*tp)) | |
380 | *walk_subtrees = 0; | |
381 | ||
382 | return NULL; | |
383 | } | |
384 | ||
385 | ||
386 | /* Translate the intermediate representation contained in the CFG | |
387 | from GIMPLE trees to RTL. | |
388 | ||
389 | We do conversion per basic block and preserve/update the tree CFG. | |
390 | This implies we have to do some magic as the CFG can simultaneously | |
391 | consist of basic blocks containing RTL and GIMPLE trees. This can | |
61ada8ae | 392 | confuse the CFG hooks, so be careful to not manipulate CFG during |
242229bb JH |
393 | the expansion. */ |
394 | ||
395 | static void | |
396 | tree_expand_cfg (void) | |
397 | { | |
398 | basic_block bb, init_block; | |
399 | sbitmap blocks; | |
400 | ||
401 | if (dump_file) | |
402 | { | |
403 | fprintf (dump_file, "\n;; Function %s", | |
404 | (*lang_hooks.decl_printable_name) (current_function_decl, 2)); | |
405 | fprintf (dump_file, " (%s)\n", | |
406 | IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (current_function_decl))); | |
407 | } | |
408 | ||
409 | /* If the function has a variably modified type, there may be | |
410 | SAVE_EXPRs in the parameter types. Their context must be set to | |
411 | refer to this function; they cannot be expanded in the containing | |
412 | function. */ | |
413 | if (decl_function_context (current_function_decl) == current_function_decl | |
414 | && variably_modified_type_p (TREE_TYPE (current_function_decl))) | |
415 | walk_tree (&TREE_TYPE (current_function_decl), set_save_expr_context, | |
416 | current_function_decl, NULL); | |
417 | ||
418 | /* Expand the variables recorded during gimple lowering. This must | |
419 | occur before the call to expand_function_start to ensure that | |
420 | all used variables are expanded before we expand anything on the | |
421 | PENDING_SIZES list. */ | |
422 | expand_used_vars (); | |
423 | ||
424 | /* Set up parameters and prepare for return, for the function. */ | |
425 | expand_function_start (current_function_decl, 0); | |
426 | ||
427 | /* If this function is `main', emit a call to `__main' | |
428 | to run global initializers, etc. */ | |
429 | if (DECL_NAME (current_function_decl) | |
430 | && MAIN_NAME_P (DECL_NAME (current_function_decl)) | |
431 | && DECL_FILE_SCOPE_P (current_function_decl)) | |
432 | expand_main_function (); | |
433 | ||
434 | /* Write the flowgraph to a dot file. */ | |
435 | rtl_register_cfg_hooks (); | |
436 | ||
437 | init_block = construct_init_block (); | |
438 | ||
439 | FOR_BB_BETWEEN (bb, init_block->next_bb, EXIT_BLOCK_PTR, next_bb) | |
440 | bb = expand_block (bb, dump_file); | |
441 | ||
442 | construct_exit_block (); | |
443 | ||
444 | /* Convert from NOTE_INSN_EH_REGION style notes, and do other | |
445 | sorts of eh initialization. Delay this until after the | |
446 | initial rtl dump so that we can see the original nesting. */ | |
447 | convert_from_eh_region_ranges (); | |
448 | ||
449 | rebuild_jump_labels (get_insns ()); | |
450 | find_exception_handler_labels (); | |
451 | ||
452 | blocks = sbitmap_alloc (last_basic_block); | |
453 | sbitmap_ones (blocks); | |
454 | find_many_sub_basic_blocks (blocks); | |
455 | purge_all_dead_edges (0); | |
456 | sbitmap_free (blocks); | |
457 | ||
458 | compact_blocks (); | |
459 | #ifdef ENABLE_CHECKING | |
460 | verify_flow_info(); | |
461 | #endif | |
462 | } | |
463 | ||
464 | struct tree_opt_pass pass_expand = | |
465 | { | |
466 | "expand", /* name */ | |
467 | NULL, /* gate */ | |
468 | tree_expand_cfg, /* execute */ | |
469 | NULL, /* sub */ | |
470 | NULL, /* next */ | |
471 | 0, /* static_pass_number */ | |
472 | TV_EXPAND, /* tv_id */ | |
473 | /* ??? If TER is enabled, we actually receive GENERIC. */ | |
474 | PROP_gimple_leh | PROP_cfg, /* properties_required */ | |
475 | PROP_rtl, /* properties_provided */ | |
476 | PROP_gimple_leh, /* properties_destroyed */ | |
477 | 0, /* todo_flags_start */ | |
478 | 0 /* todo_flags_finish */ | |
479 | }; | |
480 |