Mercurial > hg > CbC > CbC_gcc
annotate gcc/varpool.c @ 55:77e2b8dfacca gcc-4.4.5
update it from 4.4.3 to 4.5.0
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Fri, 12 Feb 2010 23:39:51 +0900 |
| parents | a06113de4d67 |
| children | b7f97abdc517 |
| rev | line source |
|---|---|
| 0 | 1 /* Callgraph handling code. |
| 2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 | |
| 3 Free Software Foundation, Inc. | |
| 4 Contributed by Jan Hubicka | |
| 5 | |
| 6 This file is part of GCC. | |
| 7 | |
| 8 GCC is free software; you can redistribute it and/or modify it under | |
| 9 the terms of the GNU General Public License as published by the Free | |
| 10 Software Foundation; either version 3, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
| 14 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 see | |
| 20 <http://www.gnu.org/licenses/>. */ | |
| 21 | |
| 22 #include "config.h" | |
| 23 #include "system.h" | |
| 24 #include "coretypes.h" | |
| 25 #include "tm.h" | |
| 26 #include "tree.h" | |
| 27 #include "cgraph.h" | |
| 28 #include "langhooks.h" | |
| 29 #include "diagnostic.h" | |
| 30 #include "hashtab.h" | |
| 31 #include "ggc.h" | |
| 32 #include "timevar.h" | |
|
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33 #include "debug.h" |
| 0 | 34 #include "target.h" |
| 35 #include "output.h" | |
| 36 #include "gimple.h" | |
| 37 #include "tree-flow.h" | |
|
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38 #include "flags.h" |
| 0 | 39 |
| 40 /* This file contains basic routines manipulating variable pool. | |
| 41 | |
| 42 Varpool acts as interface in between the front-end and middle-end | |
| 43 and drives the decision process on what variables and when are | |
| 44 going to be compiled. | |
| 45 | |
| 46 The varpool nodes are allocated lazily for declarations | |
| 47 either by frontend or at callgraph construction time. | |
| 48 All variables supposed to be output into final file needs to be | |
| 49 explicitly marked by frontend via VARPOOL_FINALIZE_DECL function. */ | |
| 50 | |
| 51 /* Hash table used to convert declarations into nodes. */ | |
| 52 static GTY((param_is (struct varpool_node))) htab_t varpool_hash; | |
| 53 | |
| 54 /* The linked list of cgraph varpool nodes. | |
| 55 Linked via node->next pointer. */ | |
| 56 struct varpool_node *varpool_nodes; | |
| 57 | |
| 58 /* Queue of cgraph nodes scheduled to be lowered and output. | |
| 59 The queue is maintained via mark_needed_node, linked via node->next_needed | |
|
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60 pointer. |
| 0 | 61 |
| 62 LAST_NEEDED_NODE points to the end of queue, so it can be | |
| 63 maintained in forward order. GTY is needed to make it friendly to | |
| 64 PCH. | |
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65 |
| 0 | 66 During compilation we construct the queue of needed variables |
| 67 twice: first time it is during cgraph construction, second time it is at the | |
| 68 end of compilation in VARPOOL_REMOVE_UNREFERENCED_DECLS so we can avoid | |
| 69 optimized out variables being output. | |
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70 |
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71 Each variable is thus first analyzed and then later possibly output. |
| 0 | 72 FIRST_UNANALYZED_NODE points to first node in queue that was not analyzed |
| 73 yet and is moved via VARPOOL_ANALYZE_PENDING_DECLS. */ | |
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74 |
| 0 | 75 struct varpool_node *varpool_nodes_queue; |
| 76 static GTY(()) struct varpool_node *varpool_last_needed_node; | |
| 77 static GTY(()) struct varpool_node *varpool_first_unanalyzed_node; | |
| 78 | |
| 79 /* Lists all assembled variables to be sent to debugger output later on. */ | |
| 80 static GTY(()) struct varpool_node *varpool_assembled_nodes_queue; | |
| 81 | |
| 82 /* Return name of the node used in debug output. */ | |
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83 const char * |
| 0 | 84 varpool_node_name (struct varpool_node *node) |
| 85 { | |
| 86 return lang_hooks.decl_printable_name (node->decl, 2); | |
| 87 } | |
| 88 | |
| 89 /* Returns a hash code for P. */ | |
| 90 static hashval_t | |
| 91 hash_varpool_node (const void *p) | |
| 92 { | |
| 93 const struct varpool_node *n = (const struct varpool_node *) p; | |
| 94 return (hashval_t) DECL_UID (n->decl); | |
| 95 } | |
| 96 | |
| 97 /* Returns nonzero if P1 and P2 are equal. */ | |
| 98 static int | |
| 99 eq_varpool_node (const void *p1, const void *p2) | |
| 100 { | |
| 101 const struct varpool_node *n1 = | |
| 102 (const struct varpool_node *) p1; | |
| 103 const struct varpool_node *n2 = | |
| 104 (const struct varpool_node *) p2; | |
| 105 return DECL_UID (n1->decl) == DECL_UID (n2->decl); | |
| 106 } | |
| 107 | |
| 108 /* Return varpool node assigned to DECL. Create new one when needed. */ | |
| 109 struct varpool_node * | |
| 110 varpool_node (tree decl) | |
| 111 { | |
| 112 struct varpool_node key, *node, **slot; | |
| 113 | |
| 114 gcc_assert (DECL_P (decl) && TREE_CODE (decl) != FUNCTION_DECL); | |
| 115 | |
| 116 if (!varpool_hash) | |
| 117 varpool_hash = htab_create_ggc (10, hash_varpool_node, | |
| 118 eq_varpool_node, NULL); | |
| 119 key.decl = decl; | |
| 120 slot = (struct varpool_node **) | |
| 121 htab_find_slot (varpool_hash, &key, INSERT); | |
| 122 if (*slot) | |
| 123 return *slot; | |
| 124 node = GGC_CNEW (struct varpool_node); | |
| 125 node->decl = decl; | |
| 126 node->order = cgraph_order++; | |
| 127 node->next = varpool_nodes; | |
| 128 varpool_nodes = node; | |
| 129 *slot = node; | |
| 130 return node; | |
| 131 } | |
| 132 | |
| 133 /* Dump given cgraph node. */ | |
| 134 void | |
| 135 dump_varpool_node (FILE *f, struct varpool_node *node) | |
| 136 { | |
| 137 fprintf (f, "%s:", varpool_node_name (node)); | |
| 138 fprintf (f, " availability:%s", | |
| 139 cgraph_function_flags_ready | |
| 140 ? cgraph_availability_names[cgraph_variable_initializer_availability (node)] | |
| 141 : "not-ready"); | |
| 142 if (DECL_INITIAL (node->decl)) | |
| 143 fprintf (f, " initialized"); | |
| 144 if (node->needed) | |
| 145 fprintf (f, " needed"); | |
| 146 if (node->analyzed) | |
| 147 fprintf (f, " analyzed"); | |
| 148 if (node->finalized) | |
| 149 fprintf (f, " finalized"); | |
| 150 if (node->output) | |
| 151 fprintf (f, " output"); | |
| 152 if (node->externally_visible) | |
| 153 fprintf (f, " externally_visible"); | |
| 154 fprintf (f, "\n"); | |
| 155 } | |
| 156 | |
| 157 /* Dump the variable pool. */ | |
| 158 void | |
| 159 dump_varpool (FILE *f) | |
| 160 { | |
| 161 struct varpool_node *node; | |
| 162 | |
| 163 fprintf (f, "variable pool:\n\n"); | |
| 164 for (node = varpool_nodes; node; node = node->next) | |
| 165 dump_varpool_node (f, node); | |
| 166 } | |
| 167 | |
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168 /* Dump the variable pool to stderr. */ |
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169 |
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170 void |
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171 debug_varpool (void) |
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172 { |
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173 dump_varpool (stderr); |
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174 } |
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175 |
| 0 | 176 /* Given an assembler name, lookup node. */ |
| 177 struct varpool_node * | |
| 178 varpool_node_for_asm (tree asmname) | |
| 179 { | |
| 180 struct varpool_node *node; | |
| 181 | |
| 182 for (node = varpool_nodes; node ; node = node->next) | |
| 183 if (decl_assembler_name_equal (node->decl, asmname)) | |
| 184 return node; | |
| 185 | |
| 186 return NULL; | |
| 187 } | |
| 188 | |
| 189 /* Helper function for finalization code - add node into lists so it will | |
| 190 be analyzed and compiled. */ | |
| 191 static void | |
| 192 varpool_enqueue_needed_node (struct varpool_node *node) | |
| 193 { | |
| 194 if (varpool_last_needed_node) | |
| 195 varpool_last_needed_node->next_needed = node; | |
| 196 varpool_last_needed_node = node; | |
| 197 node->next_needed = NULL; | |
| 198 if (!varpool_nodes_queue) | |
| 199 varpool_nodes_queue = node; | |
| 200 if (!varpool_first_unanalyzed_node) | |
| 201 varpool_first_unanalyzed_node = node; | |
| 202 notice_global_symbol (node->decl); | |
| 203 } | |
| 204 | |
| 205 /* Notify finalize_compilation_unit that given node is reachable | |
| 206 or needed. */ | |
| 207 void | |
| 208 varpool_mark_needed_node (struct varpool_node *node) | |
| 209 { | |
| 210 if (!node->needed && node->finalized | |
| 211 && !TREE_ASM_WRITTEN (node->decl)) | |
| 212 varpool_enqueue_needed_node (node); | |
| 213 node->needed = 1; | |
| 214 } | |
| 215 | |
| 216 /* Reset the queue of needed nodes. */ | |
| 217 static void | |
| 218 varpool_reset_queue (void) | |
| 219 { | |
| 220 varpool_last_needed_node = NULL; | |
| 221 varpool_nodes_queue = NULL; | |
| 222 varpool_first_unanalyzed_node = NULL; | |
| 223 } | |
| 224 | |
| 225 /* Determine if variable DECL is needed. That is, visible to something | |
| 226 either outside this translation unit, something magic in the system | |
| 227 configury */ | |
| 228 bool | |
| 229 decide_is_variable_needed (struct varpool_node *node, tree decl) | |
| 230 { | |
| 231 /* If the user told us it is used, then it must be so. */ | |
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232 if ((node->externally_visible && !DECL_COMDAT (decl)) |
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233 || node->force_output) |
| 0 | 234 return true; |
| 235 | |
| 236 /* ??? If the assembler name is set by hand, it is possible to assemble | |
| 237 the name later after finalizing the function and the fact is noticed | |
| 238 in assemble_name then. This is arguably a bug. */ | |
| 239 if (DECL_ASSEMBLER_NAME_SET_P (decl) | |
| 240 && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))) | |
| 241 return true; | |
| 242 | |
| 243 /* Externally visible variables must be output. The exception is | |
| 244 COMDAT variables that must be output only when they are needed. */ | |
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245 if (TREE_PUBLIC (decl) |
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246 && !flag_whole_program |
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247 && !flag_lto |
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248 && !flag_whopr |
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249 && !DECL_COMDAT (decl) |
| 0 | 250 && !DECL_EXTERNAL (decl)) |
| 251 return true; | |
| 252 | |
| 253 /* When emulating tls, we actually see references to the control | |
| 254 variable, rather than the user-level variable. */ | |
| 255 if (!targetm.have_tls | |
| 256 && TREE_CODE (decl) == VAR_DECL | |
| 257 && DECL_THREAD_LOCAL_P (decl)) | |
| 258 { | |
| 259 tree control = emutls_decl (decl); | |
| 260 if (decide_is_variable_needed (varpool_node (control), control)) | |
| 261 return true; | |
| 262 } | |
| 263 | |
| 264 /* When not reordering top level variables, we have to assume that | |
| 265 we are going to keep everything. */ | |
| 266 if (flag_toplevel_reorder) | |
| 267 return false; | |
| 268 | |
| 269 /* We want to emit COMDAT variables only when absolutely necessary. */ | |
| 270 if (DECL_COMDAT (decl)) | |
| 271 return false; | |
| 272 return true; | |
| 273 } | |
| 274 | |
| 275 /* Mark DECL as finalized. By finalizing the declaration, frontend instruct the | |
| 276 middle end to output the variable to asm file, if needed or externally | |
| 277 visible. */ | |
| 278 void | |
| 279 varpool_finalize_decl (tree decl) | |
| 280 { | |
| 281 struct varpool_node *node = varpool_node (decl); | |
| 282 | |
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283 /* FIXME: We don't really stream varpool datastructure and instead rebuild it |
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284 by varpool_finalize_decl. This is not quite correct since this way we can't |
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285 attach any info to varpool. Eventually we will want to stream varpool nodes |
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286 and the flags. |
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287 |
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288 For the moment just prevent analysis of varpool nodes to happen again, so |
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289 we will re-try to compute "address_taken" flag of varpool that breaks |
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290 in presence of clones. */ |
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291 if (in_lto_p) |
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292 node->analyzed = true; |
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293 |
| 0 | 294 /* The first declaration of a variable that comes through this function |
| 295 decides whether it is global (in C, has external linkage) | |
| 296 or local (in C, has internal linkage). So do nothing more | |
| 297 if this function has already run. */ | |
| 298 if (node->finalized) | |
| 299 { | |
| 300 if (cgraph_global_info_ready) | |
| 301 varpool_assemble_pending_decls (); | |
| 302 return; | |
| 303 } | |
| 304 if (node->needed) | |
| 305 varpool_enqueue_needed_node (node); | |
| 306 node->finalized = true; | |
| 307 | |
| 308 if (decide_is_variable_needed (node, decl)) | |
| 309 varpool_mark_needed_node (node); | |
| 310 /* Since we reclaim unreachable nodes at the end of every language | |
| 311 level unit, we need to be conservative about possible entry points | |
| 312 there. */ | |
| 313 else if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl) && !DECL_EXTERNAL (decl)) | |
| 314 varpool_mark_needed_node (node); | |
| 315 if (cgraph_global_info_ready) | |
| 316 varpool_assemble_pending_decls (); | |
| 317 } | |
| 318 | |
| 319 /* Return variable availability. See cgraph.h for description of individual | |
| 320 return values. */ | |
| 321 enum availability | |
| 322 cgraph_variable_initializer_availability (struct varpool_node *node) | |
| 323 { | |
| 324 gcc_assert (cgraph_function_flags_ready); | |
| 325 if (!node->finalized) | |
| 326 return AVAIL_NOT_AVAILABLE; | |
| 327 if (!TREE_PUBLIC (node->decl)) | |
| 328 return AVAIL_AVAILABLE; | |
| 329 /* If the variable can be overwritten, return OVERWRITABLE. Takes | |
| 330 care of at least two notable extensions - the COMDAT variables | |
| 331 used to share template instantiations in C++. */ | |
| 332 if (!(*targetm.binds_local_p) (node->decl) && !DECL_COMDAT (node->decl)) | |
| 333 return AVAIL_OVERWRITABLE; | |
| 334 return AVAIL_AVAILABLE; | |
| 335 } | |
| 336 | |
| 337 /* Walk the decls we marked as necessary and see if they reference new | |
| 338 variables or functions and add them into the worklists. */ | |
| 339 bool | |
| 340 varpool_analyze_pending_decls (void) | |
| 341 { | |
| 342 bool changed = false; | |
| 343 timevar_push (TV_CGRAPH); | |
| 344 | |
| 345 while (varpool_first_unanalyzed_node) | |
| 346 { | |
| 347 tree decl = varpool_first_unanalyzed_node->decl; | |
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348 bool analyzed = varpool_first_unanalyzed_node->analyzed; |
| 0 | 349 |
| 350 varpool_first_unanalyzed_node->analyzed = true; | |
| 351 | |
| 352 varpool_first_unanalyzed_node = varpool_first_unanalyzed_node->next_needed; | |
| 353 | |
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354 /* When reading back varpool at LTO time, we re-construct the queue in order |
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355 to have "needed" list right by inserting all needed nodes into varpool. |
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356 We however don't want to re-analyze already analyzed nodes. */ |
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357 if (!analyzed) |
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358 { |
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359 gcc_assert (!in_lto_p); |
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360 /* Compute the alignment early so function body expanders are |
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361 already informed about increased alignment. */ |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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changeset
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362 align_variable (decl, 0); |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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changeset
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363 } |
| 0 | 364 if (DECL_INITIAL (decl)) |
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77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
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diff
changeset
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365 record_references_in_initializer (decl, analyzed); |
| 0 | 366 changed = true; |
| 367 } | |
| 368 timevar_pop (TV_CGRAPH); | |
| 369 return changed; | |
| 370 } | |
| 371 | |
| 372 /* Output one variable, if necessary. Return whether we output it. */ | |
| 373 bool | |
| 374 varpool_assemble_decl (struct varpool_node *node) | |
| 375 { | |
| 376 tree decl = node->decl; | |
| 377 | |
| 378 if (!TREE_ASM_WRITTEN (decl) | |
| 379 && !node->alias | |
| 380 && !DECL_EXTERNAL (decl) | |
| 381 && (TREE_CODE (decl) != VAR_DECL || !DECL_HAS_VALUE_EXPR_P (decl))) | |
| 382 { | |
| 383 assemble_variable (decl, 0, 1, 0); | |
| 384 if (TREE_ASM_WRITTEN (decl)) | |
| 385 { | |
| 386 node->next_needed = varpool_assembled_nodes_queue; | |
| 387 varpool_assembled_nodes_queue = node; | |
| 388 node->finalized = 1; | |
| 389 return true; | |
| 390 } | |
| 391 } | |
| 392 | |
| 393 return false; | |
| 394 } | |
| 395 | |
| 396 /* Optimization of function bodies might've rendered some variables as | |
| 397 unnecessary so we want to avoid these from being compiled. | |
| 398 | |
| 399 This is done by pruning the queue and keeping only the variables that | |
| 400 really appear needed (ie they are either externally visible or referenced | |
| 401 by compiled function). Re-doing the reachability analysis on variables | |
| 402 brings back the remaining variables referenced by these. */ | |
| 403 void | |
| 404 varpool_remove_unreferenced_decls (void) | |
| 405 { | |
| 406 struct varpool_node *next, *node = varpool_nodes_queue; | |
| 407 | |
| 408 varpool_reset_queue (); | |
| 409 | |
| 410 if (errorcount || sorrycount) | |
| 411 return; | |
| 412 | |
| 413 while (node) | |
| 414 { | |
| 415 tree decl = node->decl; | |
| 416 next = node->next_needed; | |
| 417 node->needed = 0; | |
| 418 | |
| 419 if (node->finalized | |
| 420 && (decide_is_variable_needed (node, decl) | |
| 421 /* ??? Cgraph does not yet rule the world with an iron hand, | |
| 422 and does not control the emission of debug information. | |
| 423 After a variable has its DECL_RTL set, we must assume that | |
| 424 it may be referenced by the debug information, and we can | |
| 425 no longer elide it. */ | |
| 426 || DECL_RTL_SET_P (decl))) | |
| 427 varpool_mark_needed_node (node); | |
| 428 | |
| 429 node = next; | |
| 430 } | |
| 431 /* Make sure we mark alias targets as used targets. */ | |
| 432 finish_aliases_1 (); | |
| 433 varpool_analyze_pending_decls (); | |
| 434 } | |
| 435 | |
| 436 /* Output all variables enqueued to be assembled. */ | |
| 437 bool | |
| 438 varpool_assemble_pending_decls (void) | |
| 439 { | |
| 440 bool changed = false; | |
| 441 | |
| 442 if (errorcount || sorrycount) | |
| 443 return false; | |
| 444 | |
| 445 /* EH might mark decls as needed during expansion. This should be safe since | |
| 446 we don't create references to new function, but it should not be used | |
| 447 elsewhere. */ | |
| 448 varpool_analyze_pending_decls (); | |
| 449 | |
| 450 while (varpool_nodes_queue) | |
| 451 { | |
| 452 struct varpool_node *node = varpool_nodes_queue; | |
| 453 | |
| 454 varpool_nodes_queue = varpool_nodes_queue->next_needed; | |
| 455 if (varpool_assemble_decl (node)) | |
| 456 changed = true; | |
| 457 else | |
| 458 node->next_needed = NULL; | |
| 459 } | |
| 460 /* varpool_nodes_queue is now empty, clear the pointer to the last element | |
| 461 in the queue. */ | |
| 462 varpool_last_needed_node = NULL; | |
| 463 return changed; | |
| 464 } | |
| 465 | |
| 466 /* Remove all elements from the queue so we can re-use it for debug output. */ | |
| 467 void | |
| 468 varpool_empty_needed_queue (void) | |
| 469 { | |
| 470 /* EH might mark decls as needed during expansion. This should be safe since | |
| 471 we don't create references to new function, but it should not be used | |
| 472 elsewhere. */ | |
| 473 varpool_analyze_pending_decls (); | |
| 474 | |
| 475 while (varpool_nodes_queue) | |
| 476 { | |
| 477 struct varpool_node *node = varpool_nodes_queue; | |
| 478 varpool_nodes_queue = varpool_nodes_queue->next_needed; | |
| 479 node->next_needed = NULL; | |
| 480 } | |
| 481 /* varpool_nodes_queue is now empty, clear the pointer to the last element | |
| 482 in the queue. */ | |
| 483 varpool_last_needed_node = NULL; | |
| 484 } | |
| 485 | |
| 486 /* Create a new global variable of type TYPE. */ | |
| 487 tree | |
| 488 add_new_static_var (tree type) | |
| 489 { | |
| 490 tree new_decl; | |
| 491 struct varpool_node *new_node; | |
| 492 | |
| 493 new_decl = create_tmp_var (type, NULL); | |
| 494 DECL_NAME (new_decl) = create_tmp_var_name (NULL); | |
| 495 TREE_READONLY (new_decl) = 0; | |
| 496 TREE_STATIC (new_decl) = 1; | |
| 497 TREE_USED (new_decl) = 1; | |
| 498 DECL_CONTEXT (new_decl) = NULL_TREE; | |
| 499 DECL_ABSTRACT (new_decl) = 0; | |
| 500 lang_hooks.dup_lang_specific_decl (new_decl); | |
| 501 create_var_ann (new_decl); | |
| 502 new_node = varpool_node (new_decl); | |
| 503 varpool_mark_needed_node (new_node); | |
| 504 add_referenced_var (new_decl); | |
| 505 varpool_finalize_decl (new_decl); | |
| 506 | |
| 507 return new_node->decl; | |
| 508 } | |
| 509 | |
| 510 #include "gt-varpool.h" |