1 /* Callgraph transformations to handle inlining 2 Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010, 2011 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 /* The inline decisions are stored in callgraph in "inline plan" and 23 applied later. 24 25 To mark given call inline, use inline_call function. 26 The function marks the edge inlinable and, if necessary, produces 27 virtual clone in the callgraph representing the new copy of callee's 28 function body. 29 30 The inline plan is applied on given function body by inline_transform. */ 31 32 #include "config.h" 33 #include "system.h" 34 #include "coretypes.h" 35 #include "tm.h" 36 #include "tree.h" 37 #include "langhooks.h" 38 #include "cgraph.h" 39 #include "timevar.h" 40 #include "output.h" 41 #include "intl.h" 42 #include "coverage.h" 43 #include "ggc.h" 44 #include "tree-flow.h" 45 #include "ipa-prop.h" 46 #include "ipa-inline.h" 47 #include "tree-inline.h" 48 #include "tree-pass.h" 49 50 int ncalls_inlined; 51 int nfunctions_inlined; 52 53 /* Scale frequency of NODE edges by FREQ_SCALE. */ 54 55 static void 56 update_noncloned_frequencies (struct cgraph_node *node, 57 int freq_scale) 58 { 59 struct cgraph_edge *e; 60 61 /* We do not want to ignore high loop nest after freq drops to 0. */ 62 if (!freq_scale) 63 freq_scale = 1; 64 for (e = node->callees; e; e = e->next_callee) 65 { 66 e->frequency = e->frequency * (gcov_type) freq_scale / CGRAPH_FREQ_BASE; 67 if (e->frequency > CGRAPH_FREQ_MAX) 68 e->frequency = CGRAPH_FREQ_MAX; 69 if (!e->inline_failed) 70 update_noncloned_frequencies (e->callee, freq_scale); 71 } 72 for (e = node->indirect_calls; e; e = e->next_callee) 73 { 74 e->frequency = e->frequency * (gcov_type) freq_scale / CGRAPH_FREQ_BASE; 75 if (e->frequency > CGRAPH_FREQ_MAX) 76 e->frequency = CGRAPH_FREQ_MAX; 77 } 78 } 79 80 /* We removed or are going to remove the last call to NODE. 81 Return true if we can and want proactively remove the NODE now. 82 This is important to do, since we want inliner to know when offline 83 copy of function was removed. */ 84 85 static bool 86 can_remove_node_now_p_1 (struct cgraph_node *node) 87 { 88 /* FIXME: When address is taken of DECL_EXTERNAL function we still 89 can remove its offline copy, but we would need to keep unanalyzed node in 90 the callgraph so references can point to it. */ 91 return (!node->address_taken 92 && !ipa_ref_has_aliases_p (&node->ref_list) 93 && cgraph_can_remove_if_no_direct_calls_p (node) 94 /* Inlining might enable more devirtualizing, so we want to remove 95 those only after all devirtualizable virtual calls are processed. 96 Lacking may edges in callgraph we just preserve them post 97 inlining. */ 98 && !DECL_VIRTUAL_P (node->decl) 99 /* During early inlining some unanalyzed cgraph nodes might be in the 100 callgraph and they might reffer the function in question. */ 101 && !cgraph_new_nodes); 102 } 103 104 /* We are going to eliminate last direct call to NODE (or alias of it) via edge E. 105 Verify that the NODE can be removed from unit and if it is contained in comdat 106 group that the whole comdat group is removable. */ 107 108 static bool 109 can_remove_node_now_p (struct cgraph_node *node, struct cgraph_edge *e) 110 { 111 struct cgraph_node *next; 112 if (!can_remove_node_now_p_1 (node)) 113 return false; 114 115 /* When we see same comdat group, we need to be sure that all 116 items can be removed. */ 117 if (!node->same_comdat_group) 118 return true; 119 for (next = node->same_comdat_group; 120 next != node; next = next->same_comdat_group) 121 if ((next->callers && next->callers != e) 122 || !can_remove_node_now_p_1 (next)) 123 return false; 124 return true; 125 } 126 127 128 /* E is expected to be an edge being inlined. Clone destination node of 129 the edge and redirect it to the new clone. 130 DUPLICATE is used for bookkeeping on whether we are actually creating new 131 clones or re-using node originally representing out-of-line function call. 132 */ 133 134 void 135 clone_inlined_nodes (struct cgraph_edge *e, bool duplicate, 136 bool update_original, int *overall_size) 137 { 138 if (duplicate) 139 { 140 /* We may eliminate the need for out-of-line copy to be output. 141 In that case just go ahead and re-use it. This is not just an 142 memory optimization. Making offline copy of fuction disappear 143 from the program will improve future decisions on inlining. */ 144 if (!e->callee->callers->next_caller 145 /* Recursive inlining never wants the master clone to 146 be overwritten. */ 147 && update_original 148 && can_remove_node_now_p (e->callee, e)) 149 { 150 /* TODO: When callee is in a comdat group, we could remove all of it, 151 including all inline clones inlined into it. That would however 152 need small function inlining to register edge removal hook to 153 maintain the priority queue. 154 155 For now we keep the ohter functions in the group in program until 156 cgraph_remove_unreachable_functions gets rid of them. */ 157 gcc_assert (!e->callee->global.inlined_to); 158 if (e->callee->analyzed && !DECL_EXTERNAL (e->callee->decl)) 159 { 160 if (overall_size) 161 *overall_size -= inline_summary (e->callee)->size; 162 nfunctions_inlined++; 163 } 164 duplicate = false; 165 e->callee->local.externally_visible = false; 166 update_noncloned_frequencies (e->callee, e->frequency); 167 } 168 else 169 { 170 struct cgraph_node *n; 171 n = cgraph_clone_node (e->callee, e->callee->decl, 172 e->count, e->frequency, 173 update_original, NULL, true); 174 cgraph_redirect_edge_callee (e, n); 175 } 176 } 177 178 if (e->caller->global.inlined_to) 179 e->callee->global.inlined_to = e->caller->global.inlined_to; 180 else 181 e->callee->global.inlined_to = e->caller; 182 183 /* Recursively clone all bodies. */ 184 for (e = e->callee->callees; e; e = e->next_callee) 185 if (!e->inline_failed) 186 clone_inlined_nodes (e, duplicate, update_original, overall_size); 187 } 188 189 190 /* Mark edge E as inlined and update callgraph accordingly. UPDATE_ORIGINAL 191 specify whether profile of original function should be updated. If any new 192 indirect edges are discovered in the process, add them to NEW_EDGES, unless 193 it is NULL. Return true iff any new callgraph edges were discovered as a 194 result of inlining. */ 195 196 bool 197 inline_call (struct cgraph_edge *e, bool update_original, 198 VEC (cgraph_edge_p, heap) **new_edges, 199 int *overall_size) 200 { 201 int old_size = 0, new_size = 0; 202 struct cgraph_node *to = NULL; 203 struct cgraph_edge *curr = e; 204 struct cgraph_node *callee = cgraph_function_or_thunk_node (e->callee, NULL); 205 206 /* Don't inline inlined edges. */ 207 gcc_assert (e->inline_failed); 208 /* Don't even think of inlining inline clone. */ 209 gcc_assert (!callee->global.inlined_to); 210 211 e->inline_failed = CIF_OK; 212 DECL_POSSIBLY_INLINED (callee->decl) = true; 213 214 to = e->caller; 215 if (to->global.inlined_to) 216 to = to->global.inlined_to; 217 218 /* If aliases are involved, redirect edge to the actual destination and 219 possibly remove the aliases. */ 220 if (e->callee != callee) 221 { 222 struct cgraph_node *alias = e->callee, *next_alias; 223 cgraph_redirect_edge_callee (e, callee); 224 while (alias && alias != callee) 225 { 226 if (!alias->callers 227 && can_remove_node_now_p (alias, e)) 228 { 229 next_alias = cgraph_alias_aliased_node (alias); 230 cgraph_remove_node (alias); 231 alias = next_alias; 232 } 233 else 234 break; 235 } 236 } 237 238 clone_inlined_nodes (e, true, update_original, overall_size); 239 240 gcc_assert (curr->callee->global.inlined_to == to); 241 242 old_size = inline_summary (to)->size; 243 inline_merge_summary (e); 244 new_size = inline_summary (to)->size; 245 if (overall_size) 246 *overall_size += new_size - old_size; 247 ncalls_inlined++; 248 249 /* This must happen after inline_merge_summary that rely on jump 250 functions of callee to not be updated. */ 251 if (optimize) 252 return ipa_propagate_indirect_call_infos (curr, new_edges); 253 else 254 return false; 255 } 256 257 258 /* Copy function body of NODE and redirect all inline clones to it. 259 This is done before inline plan is applied to NODE when there are 260 still some inline clones if it. 261 262 This is neccesary because inline decisions are not really transitive 263 and the other inline clones may have different bodies. */ 264 265 static struct cgraph_node * 266 save_inline_function_body (struct cgraph_node *node) 267 { 268 struct cgraph_node *first_clone, *n; 269 270 if (dump_file) 271 fprintf (dump_file, "\nSaving body of %s for later reuse\n", 272 cgraph_node_name (node)); 273 274 gcc_assert (node == cgraph_get_node (node->decl)); 275 276 /* first_clone will be turned into real function. */ 277 first_clone = node->clones; 278 first_clone->decl = copy_node (node->decl); 279 cgraph_insert_node_to_hashtable (first_clone); 280 gcc_assert (first_clone == cgraph_get_node (first_clone->decl)); 281 282 /* Now reshape the clone tree, so all other clones descends from 283 first_clone. */ 284 if (first_clone->next_sibling_clone) 285 { 286 for (n = first_clone->next_sibling_clone; n->next_sibling_clone; n = n->next_sibling_clone) 287 n->clone_of = first_clone; 288 n->clone_of = first_clone; 289 n->next_sibling_clone = first_clone->clones; 290 if (first_clone->clones) 291 first_clone->clones->prev_sibling_clone = n; 292 first_clone->clones = first_clone->next_sibling_clone; 293 first_clone->next_sibling_clone->prev_sibling_clone = NULL; 294 first_clone->next_sibling_clone = NULL; 295 gcc_assert (!first_clone->prev_sibling_clone); 296 } 297 first_clone->clone_of = NULL; 298 299 /* Now node in question has no clones. */ 300 node->clones = NULL; 301 302 /* Inline clones share decl with the function they are cloned 303 from. Walk the whole clone tree and redirect them all to the 304 new decl. */ 305 if (first_clone->clones) 306 for (n = first_clone->clones; n != first_clone;) 307 { 308 gcc_assert (n->decl == node->decl); 309 n->decl = first_clone->decl; 310 if (n->clones) 311 n = n->clones; 312 else if (n->next_sibling_clone) 313 n = n->next_sibling_clone; 314 else 315 { 316 while (n != first_clone && !n->next_sibling_clone) 317 n = n->clone_of; 318 if (n != first_clone) 319 n = n->next_sibling_clone; 320 } 321 } 322 323 /* Copy the OLD_VERSION_NODE function tree to the new version. */ 324 tree_function_versioning (node->decl, first_clone->decl, NULL, true, NULL, 325 false, NULL, NULL); 326 327 /* The function will be short lived and removed after we inline all the clones, 328 but make it internal so we won't confuse ourself. */ 329 DECL_EXTERNAL (first_clone->decl) = 0; 330 DECL_COMDAT_GROUP (first_clone->decl) = NULL_TREE; 331 TREE_PUBLIC (first_clone->decl) = 0; 332 DECL_COMDAT (first_clone->decl) = 0; 333 VEC_free (ipa_opt_pass, heap, 334 first_clone->ipa_transforms_to_apply); 335 first_clone->ipa_transforms_to_apply = NULL; 336 337 #ifdef ENABLE_CHECKING 338 verify_cgraph_node (first_clone); 339 #endif 340 return first_clone; 341 } 342 343 344 /* Apply inline plan to function. */ 345 346 unsigned int 347 inline_transform (struct cgraph_node *node) 348 { 349 unsigned int todo = 0; 350 struct cgraph_edge *e; 351 352 /* FIXME: Currently the pass manager is adding inline transform more than 353 once to some clones. This needs revisiting after WPA cleanups. */ 354 if (cfun->after_inlining) 355 return 0; 356 357 /* We might need the body of this function so that we can expand 358 it inline somewhere else. */ 359 if (cgraph_preserve_function_body_p (node)) 360 save_inline_function_body (node); 361 362 for (e = node->callees; e; e = e->next_callee) 363 cgraph_redirect_edge_call_stmt_to_callee (e); 364 365 timevar_push (TV_INTEGRATION); 366 if (node->callees) 367 todo = optimize_inline_calls (current_function_decl); 368 timevar_pop (TV_INTEGRATION); 369 370 cfun->always_inline_functions_inlined = true; 371 cfun->after_inlining = true; 372 todo |= execute_fixup_cfg (); 373 374 if (!(todo & TODO_update_ssa_any)) 375 /* Redirecting edges might lead to a need for vops to be recomputed. */ 376 todo |= TODO_update_ssa_only_virtuals; 377 378 return todo; 379 } 380