Mercurial > hg > truffle
annotate src/share/vm/opto/gcm.cpp @ 250:6ca61c728c2d
6712835: Server compiler fails with assertion (loop_count < K,"infinite loop in PhaseIterGVN::transform")
Reviewed-by: kvn
| author | never |
|---|---|
| date | Fri, 25 Jul 2008 11:32:56 -0700 |
| parents | 9c2ecc2ffb12 |
| children | 756b58154237 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 196 | 2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
| 19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // Portions of code courtesy of Clifford Click | |
| 26 | |
| 27 // Optimization - Graph Style | |
| 28 | |
| 29 #include "incls/_precompiled.incl" | |
| 30 #include "incls/_gcm.cpp.incl" | |
| 31 | |
| 32 //----------------------------schedule_node_into_block------------------------- | |
| 33 // Insert node n into block b. Look for projections of n and make sure they | |
| 34 // are in b also. | |
| 35 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) { | |
| 36 // Set basic block of n, Add n to b, | |
| 37 _bbs.map(n->_idx, b); | |
| 38 b->add_inst(n); | |
| 39 | |
| 40 // After Matching, nearly any old Node may have projections trailing it. | |
| 41 // These are usually machine-dependent flags. In any case, they might | |
| 42 // float to another block below this one. Move them up. | |
| 43 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
| 44 Node* use = n->fast_out(i); | |
| 45 if (use->is_Proj()) { | |
| 46 Block* buse = _bbs[use->_idx]; | |
| 47 if (buse != b) { // In wrong block? | |
| 48 if (buse != NULL) | |
| 49 buse->find_remove(use); // Remove from wrong block | |
| 50 _bbs.map(use->_idx, b); // Re-insert in this block | |
| 51 b->add_inst(use); | |
| 52 } | |
| 53 } | |
| 54 } | |
| 55 } | |
| 56 | |
| 57 | |
| 58 //------------------------------schedule_pinned_nodes-------------------------- | |
| 59 // Set the basic block for Nodes pinned into blocks | |
| 60 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) { | |
| 61 // Allocate node stack of size C->unique()+8 to avoid frequent realloc | |
| 62 GrowableArray <Node *> spstack(C->unique()+8); | |
| 63 spstack.push(_root); | |
| 64 while ( spstack.is_nonempty() ) { | |
| 65 Node *n = spstack.pop(); | |
| 66 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited | |
| 67 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down! | |
| 68 Node *input = n->in(0); | |
| 69 assert( input, "pinned Node must have Control" ); | |
| 70 while( !input->is_block_start() ) | |
| 71 input = input->in(0); | |
| 72 Block *b = _bbs[input->_idx]; // Basic block of controlling input | |
| 73 schedule_node_into_block(n, b); | |
| 74 } | |
| 75 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs | |
| 76 if( n->in(i) != NULL ) | |
| 77 spstack.push(n->in(i)); | |
| 78 } | |
| 79 } | |
| 80 } | |
| 81 } | |
| 82 | |
| 83 #ifdef ASSERT | |
| 84 // Assert that new input b2 is dominated by all previous inputs. | |
| 85 // Check this by by seeing that it is dominated by b1, the deepest | |
| 86 // input observed until b2. | |
| 87 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) { | |
| 88 if (b1 == NULL) return; | |
| 89 assert(b1->_dom_depth < b2->_dom_depth, "sanity"); | |
| 90 Block* tmp = b2; | |
| 91 while (tmp != b1 && tmp != NULL) { | |
| 92 tmp = tmp->_idom; | |
| 93 } | |
| 94 if (tmp != b1) { | |
| 95 // Detected an unschedulable graph. Print some nice stuff and die. | |
| 96 tty->print_cr("!!! Unschedulable graph !!!"); | |
| 97 for (uint j=0; j<n->len(); j++) { // For all inputs | |
| 98 Node* inn = n->in(j); // Get input | |
| 99 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
| 100 Block* inb = bbs[inn->_idx]; | |
| 101 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order, | |
| 102 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth); | |
| 103 inn->dump(); | |
| 104 } | |
| 105 tty->print("Failing node: "); | |
| 106 n->dump(); | |
| 107 assert(false, "unscheduable graph"); | |
| 108 } | |
| 109 } | |
| 110 #endif | |
| 111 | |
| 112 static Block* find_deepest_input(Node* n, Block_Array &bbs) { | |
| 113 // Find the last input dominated by all other inputs. | |
| 114 Block* deepb = NULL; // Deepest block so far | |
| 115 int deepb_dom_depth = 0; | |
| 116 for (uint k = 0; k < n->len(); k++) { // For all inputs | |
| 117 Node* inn = n->in(k); // Get input | |
| 118 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
| 119 Block* inb = bbs[inn->_idx]; | |
| 120 assert(inb != NULL, "must already have scheduled this input"); | |
| 121 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
| 122 // The new inb must be dominated by the previous deepb. | |
| 123 // The various inputs must be linearly ordered in the dom | |
| 124 // tree, or else there will not be a unique deepest block. | |
| 125 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs)); | |
| 126 deepb = inb; // Save deepest block | |
| 127 deepb_dom_depth = deepb->_dom_depth; | |
| 128 } | |
| 129 } | |
| 130 assert(deepb != NULL, "must be at least one input to n"); | |
| 131 return deepb; | |
| 132 } | |
| 133 | |
| 134 | |
| 135 //------------------------------schedule_early--------------------------------- | |
| 136 // Find the earliest Block any instruction can be placed in. Some instructions | |
| 137 // are pinned into Blocks. Unpinned instructions can appear in last block in | |
| 138 // which all their inputs occur. | |
| 139 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) { | |
| 140 // Allocate stack with enough space to avoid frequent realloc | |
| 141 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats | |
| 142 // roots.push(_root); _root will be processed among C->top() inputs | |
| 143 roots.push(C->top()); | |
| 144 visited.set(C->top()->_idx); | |
| 145 | |
| 146 while (roots.size() != 0) { | |
| 147 // Use local variables nstack_top_n & nstack_top_i to cache values | |
| 148 // on stack's top. | |
| 149 Node *nstack_top_n = roots.pop(); | |
| 150 uint nstack_top_i = 0; | |
| 151 //while_nstack_nonempty: | |
| 152 while (true) { | |
| 153 // Get parent node and next input's index from stack's top. | |
| 154 Node *n = nstack_top_n; | |
| 155 uint i = nstack_top_i; | |
| 156 | |
| 157 if (i == 0) { | |
| 158 // Special control input processing. | |
| 159 // While I am here, go ahead and look for Nodes which are taking control | |
| 160 // from a is_block_proj Node. After I inserted RegionNodes to make proper | |
| 161 // blocks, the control at a is_block_proj more properly comes from the | |
| 162 // Region being controlled by the block_proj Node. | |
| 163 const Node *in0 = n->in(0); | |
| 164 if (in0 != NULL) { // Control-dependent? | |
| 165 const Node *p = in0->is_block_proj(); | |
| 166 if (p != NULL && p != n) { // Control from a block projection? | |
| 167 // Find trailing Region | |
| 168 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block | |
| 169 uint j = 0; | |
| 170 if (pb->_num_succs != 1) { // More then 1 successor? | |
| 171 // Search for successor | |
| 172 uint max = pb->_nodes.size(); | |
| 173 assert( max > 1, "" ); | |
| 174 uint start = max - pb->_num_succs; | |
| 175 // Find which output path belongs to projection | |
| 176 for (j = start; j < max; j++) { | |
| 177 if( pb->_nodes[j] == in0 ) | |
| 178 break; | |
| 179 } | |
| 180 assert( j < max, "must find" ); | |
| 181 // Change control to match head of successor basic block | |
| 182 j -= start; | |
| 183 } | |
| 184 n->set_req(0, pb->_succs[j]->head()); | |
| 185 } | |
| 186 } else { // n->in(0) == NULL | |
| 187 if (n->req() == 1) { // This guy is a constant with NO inputs? | |
| 188 n->set_req(0, _root); | |
| 189 } | |
| 190 } | |
| 191 } | |
| 192 | |
| 193 // First, visit all inputs and force them to get a block. If an | |
| 194 // input is already in a block we quit following inputs (to avoid | |
| 195 // cycles). Instead we put that Node on a worklist to be handled | |
| 196 // later (since IT'S inputs may not have a block yet). | |
| 197 bool done = true; // Assume all n's inputs will be processed | |
| 198 while (i < n->len()) { // For all inputs | |
| 199 Node *in = n->in(i); // Get input | |
| 200 ++i; | |
| 201 if (in == NULL) continue; // Ignore NULL, missing inputs | |
| 202 int is_visited = visited.test_set(in->_idx); | |
| 203 if (!_bbs.lookup(in->_idx)) { // Missing block selection? | |
| 204 if (is_visited) { | |
| 205 // assert( !visited.test(in->_idx), "did not schedule early" ); | |
| 206 return false; | |
| 207 } | |
| 208 nstack.push(n, i); // Save parent node and next input's index. | |
| 209 nstack_top_n = in; // Process current input now. | |
| 210 nstack_top_i = 0; | |
| 211 done = false; // Not all n's inputs processed. | |
| 212 break; // continue while_nstack_nonempty; | |
| 213 } else if (!is_visited) { // Input not yet visited? | |
| 214 roots.push(in); // Visit this guy later, using worklist | |
| 215 } | |
| 216 } | |
| 217 if (done) { | |
| 218 // All of n's inputs have been processed, complete post-processing. | |
| 219 | |
| 220 // Some instructions are pinned into a block. These include Region, | |
| 221 // Phi, Start, Return, and other control-dependent instructions and | |
| 222 // any projections which depend on them. | |
| 223 if (!n->pinned()) { | |
| 224 // Set earliest legal block. | |
| 225 _bbs.map(n->_idx, find_deepest_input(n, _bbs)); | |
| 226 } | |
| 227 | |
| 228 if (nstack.is_empty()) { | |
| 229 // Finished all nodes on stack. | |
| 230 // Process next node on the worklist 'roots'. | |
| 231 break; | |
| 232 } | |
| 233 // Get saved parent node and next input's index. | |
| 234 nstack_top_n = nstack.node(); | |
| 235 nstack_top_i = nstack.index(); | |
| 236 nstack.pop(); | |
| 237 } // if (done) | |
| 238 } // while (true) | |
| 239 } // while (roots.size() != 0) | |
| 240 return true; | |
| 241 } | |
| 242 | |
| 243 //------------------------------dom_lca---------------------------------------- | |
| 244 // Find least common ancestor in dominator tree | |
| 245 // LCA is a current notion of LCA, to be raised above 'this'. | |
| 246 // As a convenient boundary condition, return 'this' if LCA is NULL. | |
| 247 // Find the LCA of those two nodes. | |
| 248 Block* Block::dom_lca(Block* LCA) { | |
| 249 if (LCA == NULL || LCA == this) return this; | |
| 250 | |
| 251 Block* anc = this; | |
| 252 while (anc->_dom_depth > LCA->_dom_depth) | |
| 253 anc = anc->_idom; // Walk up till anc is as high as LCA | |
| 254 | |
| 255 while (LCA->_dom_depth > anc->_dom_depth) | |
| 256 LCA = LCA->_idom; // Walk up till LCA is as high as anc | |
| 257 | |
| 258 while (LCA != anc) { // Walk both up till they are the same | |
| 259 LCA = LCA->_idom; | |
| 260 anc = anc->_idom; | |
| 261 } | |
| 262 | |
| 263 return LCA; | |
| 264 } | |
| 265 | |
| 266 //--------------------------raise_LCA_above_use-------------------------------- | |
| 267 // We are placing a definition, and have been given a def->use edge. | |
| 268 // The definition must dominate the use, so move the LCA upward in the | |
| 269 // dominator tree to dominate the use. If the use is a phi, adjust | |
| 270 // the LCA only with the phi input paths which actually use this def. | |
| 271 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) { | |
| 272 Block* buse = bbs[use->_idx]; | |
| 273 if (buse == NULL) return LCA; // Unused killing Projs have no use block | |
| 274 if (!use->is_Phi()) return buse->dom_lca(LCA); | |
| 275 uint pmax = use->req(); // Number of Phi inputs | |
| 276 // Why does not this loop just break after finding the matching input to | |
| 277 // the Phi? Well...it's like this. I do not have true def-use/use-def | |
| 278 // chains. Means I cannot distinguish, from the def-use direction, which | |
| 279 // of many use-defs lead from the same use to the same def. That is, this | |
| 280 // Phi might have several uses of the same def. Each use appears in a | |
| 281 // different predecessor block. But when I enter here, I cannot distinguish | |
| 282 // which use-def edge I should find the predecessor block for. So I find | |
| 283 // them all. Means I do a little extra work if a Phi uses the same value | |
| 284 // more than once. | |
| 285 for (uint j=1; j<pmax; j++) { // For all inputs | |
| 286 if (use->in(j) == def) { // Found matching input? | |
| 287 Block* pred = bbs[buse->pred(j)->_idx]; | |
| 288 LCA = pred->dom_lca(LCA); | |
| 289 } | |
| 290 } | |
| 291 return LCA; | |
| 292 } | |
| 293 | |
| 294 //----------------------------raise_LCA_above_marks---------------------------- | |
| 295 // Return a new LCA that dominates LCA and any of its marked predecessors. | |
| 296 // Search all my parents up to 'early' (exclusive), looking for predecessors | |
| 297 // which are marked with the given index. Return the LCA (in the dom tree) | |
| 298 // of all marked blocks. If there are none marked, return the original | |
| 299 // LCA. | |
| 300 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, | |
| 301 Block* early, Block_Array &bbs) { | |
| 302 Block_List worklist; | |
| 303 worklist.push(LCA); | |
| 304 while (worklist.size() > 0) { | |
| 305 Block* mid = worklist.pop(); | |
| 306 if (mid == early) continue; // stop searching here | |
| 307 | |
| 308 // Test and set the visited bit. | |
| 309 if (mid->raise_LCA_visited() == mark) continue; // already visited | |
| 310 | |
| 311 // Don't process the current LCA, otherwise the search may terminate early | |
| 312 if (mid != LCA && mid->raise_LCA_mark() == mark) { | |
| 313 // Raise the LCA. | |
| 314 LCA = mid->dom_lca(LCA); | |
| 315 if (LCA == early) break; // stop searching everywhere | |
| 316 assert(early->dominates(LCA), "early is high enough"); | |
| 317 // Resume searching at that point, skipping intermediate levels. | |
| 318 worklist.push(LCA); | |
|
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319 if (LCA == mid) |
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320 continue; // Don't mark as visited to avoid early termination. |
| 0 | 321 } else { |
| 322 // Keep searching through this block's predecessors. | |
| 323 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { | |
| 324 Block* mid_parent = bbs[ mid->pred(j)->_idx ]; | |
| 325 worklist.push(mid_parent); | |
| 326 } | |
| 327 } | |
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328 mid->set_raise_LCA_visited(mark); |
| 0 | 329 } |
| 330 return LCA; | |
| 331 } | |
| 332 | |
| 333 //--------------------------memory_early_block-------------------------------- | |
| 334 // This is a variation of find_deepest_input, the heart of schedule_early. | |
| 335 // Find the "early" block for a load, if we considered only memory and | |
| 336 // address inputs, that is, if other data inputs were ignored. | |
| 337 // | |
| 338 // Because a subset of edges are considered, the resulting block will | |
| 339 // be earlier (at a shallower dom_depth) than the true schedule_early | |
| 340 // point of the node. We compute this earlier block as a more permissive | |
| 341 // site for anti-dependency insertion, but only if subsume_loads is enabled. | |
| 342 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) { | |
| 343 Node* base; | |
| 344 Node* index; | |
| 345 Node* store = load->in(MemNode::Memory); | |
| 346 load->as_Mach()->memory_inputs(base, index); | |
| 347 | |
| 348 assert(base != NodeSentinel && index != NodeSentinel, | |
| 349 "unexpected base/index inputs"); | |
| 350 | |
| 351 Node* mem_inputs[4]; | |
| 352 int mem_inputs_length = 0; | |
| 353 if (base != NULL) mem_inputs[mem_inputs_length++] = base; | |
| 354 if (index != NULL) mem_inputs[mem_inputs_length++] = index; | |
| 355 if (store != NULL) mem_inputs[mem_inputs_length++] = store; | |
| 356 | |
| 357 // In the comparision below, add one to account for the control input, | |
| 358 // which may be null, but always takes up a spot in the in array. | |
| 359 if (mem_inputs_length + 1 < (int) load->req()) { | |
| 360 // This "load" has more inputs than just the memory, base and index inputs. | |
| 361 // For purposes of checking anti-dependences, we need to start | |
| 362 // from the early block of only the address portion of the instruction, | |
| 363 // and ignore other blocks that may have factored into the wider | |
| 364 // schedule_early calculation. | |
| 365 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0); | |
| 366 | |
| 367 Block* deepb = NULL; // Deepest block so far | |
| 368 int deepb_dom_depth = 0; | |
| 369 for (int i = 0; i < mem_inputs_length; i++) { | |
| 370 Block* inb = bbs[mem_inputs[i]->_idx]; | |
| 371 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
| 372 // The new inb must be dominated by the previous deepb. | |
| 373 // The various inputs must be linearly ordered in the dom | |
| 374 // tree, or else there will not be a unique deepest block. | |
| 375 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs)); | |
| 376 deepb = inb; // Save deepest block | |
| 377 deepb_dom_depth = deepb->_dom_depth; | |
| 378 } | |
| 379 } | |
| 380 early = deepb; | |
| 381 } | |
| 382 | |
| 383 return early; | |
| 384 } | |
| 385 | |
| 386 //--------------------------insert_anti_dependences--------------------------- | |
| 387 // A load may need to witness memory that nearby stores can overwrite. | |
| 388 // For each nearby store, either insert an "anti-dependence" edge | |
| 389 // from the load to the store, or else move LCA upward to force the | |
| 390 // load to (eventually) be scheduled in a block above the store. | |
| 391 // | |
| 392 // Do not add edges to stores on distinct control-flow paths; | |
| 393 // only add edges to stores which might interfere. | |
| 394 // | |
| 395 // Return the (updated) LCA. There will not be any possibly interfering | |
| 396 // store between the load's "early block" and the updated LCA. | |
| 397 // Any stores in the updated LCA will have new precedence edges | |
| 398 // back to the load. The caller is expected to schedule the load | |
| 399 // in the LCA, in which case the precedence edges will make LCM | |
| 400 // preserve anti-dependences. The caller may also hoist the load | |
| 401 // above the LCA, if it is not the early block. | |
| 402 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) { | |
| 403 assert(load->needs_anti_dependence_check(), "must be a load of some sort"); | |
| 404 assert(LCA != NULL, ""); | |
| 405 DEBUG_ONLY(Block* LCA_orig = LCA); | |
| 406 | |
| 407 // Compute the alias index. Loads and stores with different alias indices | |
| 408 // do not need anti-dependence edges. | |
| 409 uint load_alias_idx = C->get_alias_index(load->adr_type()); | |
| 410 #ifdef ASSERT | |
| 411 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 && | |
| 412 (PrintOpto || VerifyAliases || | |
| 413 PrintMiscellaneous && (WizardMode || Verbose))) { | |
| 414 // Load nodes should not consume all of memory. | |
| 415 // Reporting a bottom type indicates a bug in adlc. | |
| 416 // If some particular type of node validly consumes all of memory, | |
| 417 // sharpen the preceding "if" to exclude it, so we can catch bugs here. | |
| 418 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory."); | |
| 419 load->dump(2); | |
| 420 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, ""); | |
| 421 } | |
| 422 #endif | |
| 423 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp), | |
| 424 "String compare is only known 'load' that does not conflict with any stores"); | |
| 425 | |
| 426 if (!C->alias_type(load_alias_idx)->is_rewritable()) { | |
| 427 // It is impossible to spoil this load by putting stores before it, | |
| 428 // because we know that the stores will never update the value | |
| 429 // which 'load' must witness. | |
| 430 return LCA; | |
| 431 } | |
| 432 | |
| 433 node_idx_t load_index = load->_idx; | |
| 434 | |
| 435 // Note the earliest legal placement of 'load', as determined by | |
| 436 // by the unique point in the dom tree where all memory effects | |
| 437 // and other inputs are first available. (Computed by schedule_early.) | |
| 438 // For normal loads, 'early' is the shallowest place (dom graph wise) | |
| 439 // to look for anti-deps between this load and any store. | |
| 440 Block* early = _bbs[load_index]; | |
| 441 | |
| 442 // If we are subsuming loads, compute an "early" block that only considers | |
| 443 // memory or address inputs. This block may be different than the | |
| 444 // schedule_early block in that it could be at an even shallower depth in the | |
| 445 // dominator tree, and allow for a broader discovery of anti-dependences. | |
| 446 if (C->subsume_loads()) { | |
| 447 early = memory_early_block(load, early, _bbs); | |
| 448 } | |
| 449 | |
| 450 ResourceArea *area = Thread::current()->resource_area(); | |
| 451 Node_List worklist_mem(area); // prior memory state to store | |
| 452 Node_List worklist_store(area); // possible-def to explore | |
|
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453 Node_List worklist_visited(area); // visited mergemem nodes |
| 0 | 454 Node_List non_early_stores(area); // all relevant stores outside of early |
| 455 bool must_raise_LCA = false; | |
| 456 | |
| 457 #ifdef TRACK_PHI_INPUTS | |
| 458 // %%% This extra checking fails because MergeMem nodes are not GVNed. | |
| 459 // Provide "phi_inputs" to check if every input to a PhiNode is from the | |
| 460 // original memory state. This indicates a PhiNode for which should not | |
| 461 // prevent the load from sinking. For such a block, set_raise_LCA_mark | |
| 462 // may be overly conservative. | |
| 463 // Mechanism: count inputs seen for each Phi encountered in worklist_store. | |
| 464 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0)); | |
| 465 #endif | |
| 466 | |
| 467 // 'load' uses some memory state; look for users of the same state. | |
| 468 // Recurse through MergeMem nodes to the stores that use them. | |
| 469 | |
| 470 // Each of these stores is a possible definition of memory | |
| 471 // that 'load' needs to use. We need to force 'load' | |
| 472 // to occur before each such store. When the store is in | |
| 473 // the same block as 'load', we insert an anti-dependence | |
| 474 // edge load->store. | |
| 475 | |
| 476 // The relevant stores "nearby" the load consist of a tree rooted | |
| 477 // at initial_mem, with internal nodes of type MergeMem. | |
| 478 // Therefore, the branches visited by the worklist are of this form: | |
| 479 // initial_mem -> (MergeMem ->)* store | |
| 480 // The anti-dependence constraints apply only to the fringe of this tree. | |
| 481 | |
| 482 Node* initial_mem = load->in(MemNode::Memory); | |
| 483 worklist_store.push(initial_mem); | |
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484 worklist_visited.push(initial_mem); |
| 0 | 485 worklist_mem.push(NULL); |
| 486 while (worklist_store.size() > 0) { | |
| 487 // Examine a nearby store to see if it might interfere with our load. | |
| 488 Node* mem = worklist_mem.pop(); | |
| 489 Node* store = worklist_store.pop(); | |
| 490 uint op = store->Opcode(); | |
| 491 | |
| 492 // MergeMems do not directly have anti-deps. | |
| 493 // Treat them as internal nodes in a forward tree of memory states, | |
| 494 // the leaves of which are each a 'possible-def'. | |
| 495 if (store == initial_mem // root (exclusive) of tree we are searching | |
| 496 || op == Op_MergeMem // internal node of tree we are searching | |
| 497 ) { | |
| 498 mem = store; // It's not a possibly interfering store. | |
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499 if (store == initial_mem) |
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500 initial_mem = NULL; // only process initial memory once |
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501 |
| 0 | 502 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { |
| 503 store = mem->fast_out(i); | |
| 504 if (store->is_MergeMem()) { | |
| 505 // Be sure we don't get into combinatorial problems. | |
| 506 // (Allow phis to be repeated; they can merge two relevant states.) | |
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507 uint j = worklist_visited.size(); |
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508 for (; j > 0; j--) { |
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509 if (worklist_visited.at(j-1) == store) break; |
| 0 | 510 } |
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511 if (j > 0) continue; // already on work list; do not repeat |
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512 worklist_visited.push(store); |
| 0 | 513 } |
| 514 worklist_mem.push(mem); | |
| 515 worklist_store.push(store); | |
| 516 } | |
| 517 continue; | |
| 518 } | |
| 519 | |
| 520 if (op == Op_MachProj || op == Op_Catch) continue; | |
| 521 if (store->needs_anti_dependence_check()) continue; // not really a store | |
| 522 | |
| 523 // Compute the alias index. Loads and stores with different alias | |
| 524 // indices do not need anti-dependence edges. Wide MemBar's are | |
| 525 // anti-dependent on everything (except immutable memories). | |
| 526 const TypePtr* adr_type = store->adr_type(); | |
| 527 if (!C->can_alias(adr_type, load_alias_idx)) continue; | |
| 528 | |
| 529 // Most slow-path runtime calls do NOT modify Java memory, but | |
| 530 // they can block and so write Raw memory. | |
| 531 if (store->is_Mach()) { | |
| 532 MachNode* mstore = store->as_Mach(); | |
| 533 if (load_alias_idx != Compile::AliasIdxRaw) { | |
| 534 // Check for call into the runtime using the Java calling | |
| 535 // convention (and from there into a wrapper); it has no | |
| 536 // _method. Can't do this optimization for Native calls because | |
| 537 // they CAN write to Java memory. | |
| 538 if (mstore->ideal_Opcode() == Op_CallStaticJava) { | |
| 539 assert(mstore->is_MachSafePoint(), ""); | |
| 540 MachSafePointNode* ms = (MachSafePointNode*) mstore; | |
| 541 assert(ms->is_MachCallJava(), ""); | |
| 542 MachCallJavaNode* mcj = (MachCallJavaNode*) ms; | |
| 543 if (mcj->_method == NULL) { | |
| 544 // These runtime calls do not write to Java visible memory | |
| 545 // (other than Raw) and so do not require anti-dependence edges. | |
| 546 continue; | |
| 547 } | |
| 548 } | |
| 549 // Same for SafePoints: they read/write Raw but only read otherwise. | |
| 550 // This is basically a workaround for SafePoints only defining control | |
| 551 // instead of control + memory. | |
| 552 if (mstore->ideal_Opcode() == Op_SafePoint) | |
| 553 continue; | |
| 554 } else { | |
| 555 // Some raw memory, such as the load of "top" at an allocation, | |
| 556 // can be control dependent on the previous safepoint. See | |
| 557 // comments in GraphKit::allocate_heap() about control input. | |
| 558 // Inserting an anti-dep between such a safepoint and a use | |
| 559 // creates a cycle, and will cause a subsequent failure in | |
| 560 // local scheduling. (BugId 4919904) | |
| 561 // (%%% How can a control input be a safepoint and not a projection??) | |
| 562 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore) | |
| 563 continue; | |
| 564 } | |
| 565 } | |
| 566 | |
| 567 // Identify a block that the current load must be above, | |
| 568 // or else observe that 'store' is all the way up in the | |
| 569 // earliest legal block for 'load'. In the latter case, | |
| 570 // immediately insert an anti-dependence edge. | |
| 571 Block* store_block = _bbs[store->_idx]; | |
| 572 assert(store_block != NULL, "unused killing projections skipped above"); | |
| 573 | |
| 574 if (store->is_Phi()) { | |
| 575 // 'load' uses memory which is one (or more) of the Phi's inputs. | |
| 576 // It must be scheduled not before the Phi, but rather before | |
| 577 // each of the relevant Phi inputs. | |
| 578 // | |
| 579 // Instead of finding the LCA of all inputs to a Phi that match 'mem', | |
| 580 // we mark each corresponding predecessor block and do a combined | |
| 581 // hoisting operation later (raise_LCA_above_marks). | |
| 582 // | |
| 583 // Do not assert(store_block != early, "Phi merging memory after access") | |
| 584 // PhiNode may be at start of block 'early' with backedge to 'early' | |
| 585 DEBUG_ONLY(bool found_match = false); | |
| 586 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) { | |
| 587 if (store->in(j) == mem) { // Found matching input? | |
| 588 DEBUG_ONLY(found_match = true); | |
| 589 Block* pred_block = _bbs[store_block->pred(j)->_idx]; | |
| 590 if (pred_block != early) { | |
| 591 // If any predecessor of the Phi matches the load's "early block", | |
| 592 // we do not need a precedence edge between the Phi and 'load' | |
| 593 // since the load will be forced into a block preceeding the Phi. | |
| 594 pred_block->set_raise_LCA_mark(load_index); | |
| 595 assert(!LCA_orig->dominates(pred_block) || | |
| 596 early->dominates(pred_block), "early is high enough"); | |
| 597 must_raise_LCA = true; | |
| 598 } | |
| 599 } | |
| 600 } | |
| 601 assert(found_match, "no worklist bug"); | |
| 602 #ifdef TRACK_PHI_INPUTS | |
| 603 #ifdef ASSERT | |
| 604 // This assert asks about correct handling of PhiNodes, which may not | |
| 605 // have all input edges directly from 'mem'. See BugId 4621264 | |
| 606 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1; | |
| 607 // Increment by exactly one even if there are multiple copies of 'mem' | |
| 608 // coming into the phi, because we will run this block several times | |
| 609 // if there are several copies of 'mem'. (That's how DU iterators work.) | |
| 610 phi_inputs.at_put(store->_idx, num_mem_inputs); | |
| 611 assert(PhiNode::Input + num_mem_inputs < store->req(), | |
| 612 "Expect at least one phi input will not be from original memory state"); | |
| 613 #endif //ASSERT | |
| 614 #endif //TRACK_PHI_INPUTS | |
| 615 } else if (store_block != early) { | |
| 616 // 'store' is between the current LCA and earliest possible block. | |
| 617 // Label its block, and decide later on how to raise the LCA | |
| 618 // to include the effect on LCA of this store. | |
| 619 // If this store's block gets chosen as the raised LCA, we | |
| 620 // will find him on the non_early_stores list and stick him | |
| 621 // with a precedence edge. | |
| 622 // (But, don't bother if LCA is already raised all the way.) | |
| 623 if (LCA != early) { | |
| 624 store_block->set_raise_LCA_mark(load_index); | |
| 625 must_raise_LCA = true; | |
| 626 non_early_stores.push(store); | |
| 627 } | |
| 628 } else { | |
| 629 // Found a possibly-interfering store in the load's 'early' block. | |
| 630 // This means 'load' cannot sink at all in the dominator tree. | |
| 631 // Add an anti-dep edge, and squeeze 'load' into the highest block. | |
| 632 assert(store != load->in(0), "dependence cycle found"); | |
| 633 if (verify) { | |
| 634 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
| 635 } else { | |
| 636 store->add_prec(load); | |
| 637 } | |
| 638 LCA = early; | |
| 639 // This turns off the process of gathering non_early_stores. | |
| 640 } | |
| 641 } | |
| 642 // (Worklist is now empty; all nearby stores have been visited.) | |
| 643 | |
| 644 // Finished if 'load' must be scheduled in its 'early' block. | |
| 645 // If we found any stores there, they have already been given | |
| 646 // precedence edges. | |
| 647 if (LCA == early) return LCA; | |
| 648 | |
| 649 // We get here only if there are no possibly-interfering stores | |
| 650 // in the load's 'early' block. Move LCA up above all predecessors | |
| 651 // which contain stores we have noted. | |
| 652 // | |
| 653 // The raised LCA block can be a home to such interfering stores, | |
| 654 // but its predecessors must not contain any such stores. | |
| 655 // | |
| 656 // The raised LCA will be a lower bound for placing the load, | |
| 657 // preventing the load from sinking past any block containing | |
| 658 // a store that may invalidate the memory state required by 'load'. | |
| 659 if (must_raise_LCA) | |
| 660 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs); | |
| 661 if (LCA == early) return LCA; | |
| 662 | |
| 663 // Insert anti-dependence edges from 'load' to each store | |
| 664 // in the non-early LCA block. | |
| 665 // Mine the non_early_stores list for such stores. | |
| 666 if (LCA->raise_LCA_mark() == load_index) { | |
| 667 while (non_early_stores.size() > 0) { | |
| 668 Node* store = non_early_stores.pop(); | |
| 669 Block* store_block = _bbs[store->_idx]; | |
| 670 if (store_block == LCA) { | |
| 671 // add anti_dependence from store to load in its own block | |
| 672 assert(store != load->in(0), "dependence cycle found"); | |
| 673 if (verify) { | |
| 674 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
| 675 } else { | |
| 676 store->add_prec(load); | |
| 677 } | |
| 678 } else { | |
| 679 assert(store_block->raise_LCA_mark() == load_index, "block was marked"); | |
| 680 // Any other stores we found must be either inside the new LCA | |
| 681 // or else outside the original LCA. In the latter case, they | |
| 682 // did not interfere with any use of 'load'. | |
| 683 assert(LCA->dominates(store_block) | |
| 684 || !LCA_orig->dominates(store_block), "no stray stores"); | |
| 685 } | |
| 686 } | |
| 687 } | |
| 688 | |
| 689 // Return the highest block containing stores; any stores | |
| 690 // within that block have been given anti-dependence edges. | |
| 691 return LCA; | |
| 692 } | |
| 693 | |
| 694 // This class is used to iterate backwards over the nodes in the graph. | |
| 695 | |
| 696 class Node_Backward_Iterator { | |
| 697 | |
| 698 private: | |
| 699 Node_Backward_Iterator(); | |
| 700 | |
| 701 public: | |
| 702 // Constructor for the iterator | |
| 703 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs); | |
| 704 | |
| 705 // Postincrement operator to iterate over the nodes | |
| 706 Node *next(); | |
| 707 | |
| 708 private: | |
| 709 VectorSet &_visited; | |
| 710 Node_List &_stack; | |
| 711 Block_Array &_bbs; | |
| 712 }; | |
| 713 | |
| 714 // Constructor for the Node_Backward_Iterator | |
| 715 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs ) | |
| 716 : _visited(visited), _stack(stack), _bbs(bbs) { | |
| 717 // The stack should contain exactly the root | |
| 718 stack.clear(); | |
| 719 stack.push(root); | |
| 720 | |
| 721 // Clear the visited bits | |
| 722 visited.Clear(); | |
| 723 } | |
| 724 | |
| 725 // Iterator for the Node_Backward_Iterator | |
| 726 Node *Node_Backward_Iterator::next() { | |
| 727 | |
| 728 // If the _stack is empty, then just return NULL: finished. | |
| 729 if ( !_stack.size() ) | |
| 730 return NULL; | |
| 731 | |
| 732 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been | |
| 733 // made stateless, so I do not need to record the index 'i' on my _stack. | |
| 734 // Instead I visit all users each time, scanning for unvisited users. | |
| 735 // I visit unvisited not-anti-dependence users first, then anti-dependent | |
| 736 // children next. | |
| 737 Node *self = _stack.pop(); | |
| 738 | |
| 739 // I cycle here when I am entering a deeper level of recursion. | |
| 740 // The key variable 'self' was set prior to jumping here. | |
| 741 while( 1 ) { | |
| 742 | |
| 743 _visited.set(self->_idx); | |
| 744 | |
| 745 // Now schedule all uses as late as possible. | |
| 746 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx; | |
| 747 uint src_rpo = _bbs[src]->_rpo; | |
| 748 | |
| 749 // Schedule all nodes in a post-order visit | |
| 750 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any | |
| 751 | |
| 752 // Scan for unvisited nodes | |
| 753 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
| 754 // For all uses, schedule late | |
| 755 Node* n = self->fast_out(i); // Use | |
| 756 | |
| 757 // Skip already visited children | |
| 758 if ( _visited.test(n->_idx) ) | |
| 759 continue; | |
| 760 | |
| 761 // do not traverse backward control edges | |
| 762 Node *use = n->is_Proj() ? n->in(0) : n; | |
| 763 uint use_rpo = _bbs[use->_idx]->_rpo; | |
| 764 | |
| 765 if ( use_rpo < src_rpo ) | |
| 766 continue; | |
| 767 | |
| 768 // Phi nodes always precede uses in a basic block | |
| 769 if ( use_rpo == src_rpo && use->is_Phi() ) | |
| 770 continue; | |
| 771 | |
| 772 unvisited = n; // Found unvisited | |
| 773 | |
| 774 // Check for possible-anti-dependent | |
| 775 if( !n->needs_anti_dependence_check() ) | |
| 776 break; // Not visited, not anti-dep; schedule it NOW | |
| 777 } | |
| 778 | |
| 779 // Did I find an unvisited not-anti-dependent Node? | |
| 780 if ( !unvisited ) | |
| 781 break; // All done with children; post-visit 'self' | |
| 782 | |
| 783 // Visit the unvisited Node. Contains the obvious push to | |
| 784 // indicate I'm entering a deeper level of recursion. I push the | |
| 785 // old state onto the _stack and set a new state and loop (recurse). | |
| 786 _stack.push(self); | |
| 787 self = unvisited; | |
| 788 } // End recursion loop | |
| 789 | |
| 790 return self; | |
| 791 } | |
| 792 | |
| 793 //------------------------------ComputeLatenciesBackwards---------------------- | |
| 794 // Compute the latency of all the instructions. | |
| 795 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) { | |
| 796 #ifndef PRODUCT | |
| 797 if (trace_opto_pipelining()) | |
| 798 tty->print("\n#---- ComputeLatenciesBackwards ----\n"); | |
| 799 #endif | |
| 800 | |
| 801 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
| 802 Node *n; | |
| 803 | |
| 804 // Walk over all the nodes from last to first | |
| 805 while (n = iter.next()) { | |
| 806 // Set the latency for the definitions of this instruction | |
| 807 partial_latency_of_defs(n); | |
| 808 } | |
| 809 } // end ComputeLatenciesBackwards | |
| 810 | |
| 811 //------------------------------partial_latency_of_defs------------------------ | |
| 812 // Compute the latency impact of this node on all defs. This computes | |
| 813 // a number that increases as we approach the beginning of the routine. | |
| 814 void PhaseCFG::partial_latency_of_defs(Node *n) { | |
| 815 // Set the latency for this instruction | |
| 816 #ifndef PRODUCT | |
| 817 if (trace_opto_pipelining()) { | |
| 818 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", | |
| 819 n->_idx, _node_latency.at_grow(n->_idx)); | |
| 820 dump(); | |
| 821 } | |
| 822 #endif | |
| 823 | |
| 824 if (n->is_Proj()) | |
| 825 n = n->in(0); | |
| 826 | |
| 827 if (n->is_Root()) | |
| 828 return; | |
| 829 | |
| 830 uint nlen = n->len(); | |
| 831 uint use_latency = _node_latency.at_grow(n->_idx); | |
| 832 uint use_pre_order = _bbs[n->_idx]->_pre_order; | |
| 833 | |
| 834 for ( uint j=0; j<nlen; j++ ) { | |
| 835 Node *def = n->in(j); | |
| 836 | |
| 837 if (!def || def == n) | |
| 838 continue; | |
| 839 | |
| 840 // Walk backwards thru projections | |
| 841 if (def->is_Proj()) | |
| 842 def = def->in(0); | |
| 843 | |
| 844 #ifndef PRODUCT | |
| 845 if (trace_opto_pipelining()) { | |
| 846 tty->print("# in(%2d): ", j); | |
| 847 def->dump(); | |
| 848 } | |
| 849 #endif | |
| 850 | |
| 851 // If the defining block is not known, assume it is ok | |
| 852 Block *def_block = _bbs[def->_idx]; | |
| 853 uint def_pre_order = def_block ? def_block->_pre_order : 0; | |
| 854 | |
| 855 if ( (use_pre_order < def_pre_order) || | |
| 856 (use_pre_order == def_pre_order && n->is_Phi()) ) | |
| 857 continue; | |
| 858 | |
| 859 uint delta_latency = n->latency(j); | |
| 860 uint current_latency = delta_latency + use_latency; | |
| 861 | |
| 862 if (_node_latency.at_grow(def->_idx) < current_latency) { | |
| 863 _node_latency.at_put_grow(def->_idx, current_latency); | |
| 864 } | |
| 865 | |
| 866 #ifndef PRODUCT | |
| 867 if (trace_opto_pipelining()) { | |
| 868 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", | |
| 869 use_latency, j, delta_latency, current_latency, def->_idx, | |
| 870 _node_latency.at_grow(def->_idx)); | |
| 871 } | |
| 872 #endif | |
| 873 } | |
| 874 } | |
| 875 | |
| 876 //------------------------------latency_from_use------------------------------- | |
| 877 // Compute the latency of a specific use | |
| 878 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) { | |
| 879 // If self-reference, return no latency | |
| 880 if (use == n || use->is_Root()) | |
| 881 return 0; | |
| 882 | |
| 883 uint def_pre_order = _bbs[def->_idx]->_pre_order; | |
| 884 uint latency = 0; | |
| 885 | |
| 886 // If the use is not a projection, then it is simple... | |
| 887 if (!use->is_Proj()) { | |
| 888 #ifndef PRODUCT | |
| 889 if (trace_opto_pipelining()) { | |
| 890 tty->print("# out(): "); | |
| 891 use->dump(); | |
| 892 } | |
| 893 #endif | |
| 894 | |
| 895 uint use_pre_order = _bbs[use->_idx]->_pre_order; | |
| 896 | |
| 897 if (use_pre_order < def_pre_order) | |
| 898 return 0; | |
| 899 | |
| 900 if (use_pre_order == def_pre_order && use->is_Phi()) | |
| 901 return 0; | |
| 902 | |
| 903 uint nlen = use->len(); | |
| 904 uint nl = _node_latency.at_grow(use->_idx); | |
| 905 | |
| 906 for ( uint j=0; j<nlen; j++ ) { | |
| 907 if (use->in(j) == n) { | |
| 908 // Change this if we want local latencies | |
| 909 uint ul = use->latency(j); | |
| 910 uint l = ul + nl; | |
| 911 if (latency < l) latency = l; | |
| 912 #ifndef PRODUCT | |
| 913 if (trace_opto_pipelining()) { | |
| 914 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d", | |
| 915 nl, j, ul, l, latency); | |
| 916 } | |
| 917 #endif | |
| 918 } | |
| 919 } | |
| 920 } else { | |
| 921 // This is a projection, just grab the latency of the use(s) | |
| 922 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) { | |
| 923 uint l = latency_from_use(use, def, use->fast_out(j)); | |
| 924 if (latency < l) latency = l; | |
| 925 } | |
| 926 } | |
| 927 | |
| 928 return latency; | |
| 929 } | |
| 930 | |
| 931 //------------------------------latency_from_uses------------------------------ | |
| 932 // Compute the latency of this instruction relative to all of it's uses. | |
| 933 // This computes a number that increases as we approach the beginning of the | |
| 934 // routine. | |
| 935 void PhaseCFG::latency_from_uses(Node *n) { | |
| 936 // Set the latency for this instruction | |
| 937 #ifndef PRODUCT | |
| 938 if (trace_opto_pipelining()) { | |
| 939 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", | |
| 940 n->_idx, _node_latency.at_grow(n->_idx)); | |
| 941 dump(); | |
| 942 } | |
| 943 #endif | |
| 944 uint latency=0; | |
| 945 const Node *def = n->is_Proj() ? n->in(0): n; | |
| 946 | |
| 947 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
| 948 uint l = latency_from_use(n, def, n->fast_out(i)); | |
| 949 | |
| 950 if (latency < l) latency = l; | |
| 951 } | |
| 952 | |
| 953 _node_latency.at_put_grow(n->_idx, latency); | |
| 954 } | |
| 955 | |
| 956 //------------------------------hoist_to_cheaper_block------------------------- | |
| 957 // Pick a block for node self, between early and LCA, that is a cheaper | |
| 958 // alternative to LCA. | |
| 959 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) { | |
| 960 const double delta = 1+PROB_UNLIKELY_MAG(4); | |
| 961 Block* least = LCA; | |
| 962 double least_freq = least->_freq; | |
| 963 uint target = _node_latency.at_grow(self->_idx); | |
| 964 uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
| 965 uint end_latency = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx); | |
| 966 bool in_latency = (target <= start_latency); | |
| 967 const Block* root_block = _bbs[_root->_idx]; | |
| 968 | |
| 969 // Turn off latency scheduling if scheduling is just plain off | |
| 970 if (!C->do_scheduling()) | |
| 971 in_latency = true; | |
| 972 | |
| 973 // Do not hoist (to cover latency) instructions which target a | |
| 974 // single register. Hoisting stretches the live range of the | |
| 975 // single register and may force spilling. | |
| 976 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
| 977 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty()) | |
| 978 in_latency = true; | |
| 979 | |
| 980 #ifndef PRODUCT | |
| 981 if (trace_opto_pipelining()) { | |
| 982 tty->print("# Find cheaper block for latency %d: ", | |
| 983 _node_latency.at_grow(self->_idx)); | |
| 984 self->dump(); | |
| 985 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
| 986 LCA->_pre_order, | |
| 987 LCA->_nodes[0]->_idx, | |
| 988 start_latency, | |
| 989 LCA->_nodes[LCA->end_idx()]->_idx, | |
| 990 end_latency, | |
| 991 least_freq); | |
| 992 } | |
| 993 #endif | |
| 994 | |
| 995 // Walk up the dominator tree from LCA (Lowest common ancestor) to | |
| 996 // the earliest legal location. Capture the least execution frequency. | |
| 997 while (LCA != early) { | |
| 998 LCA = LCA->_idom; // Follow up the dominator tree | |
| 999 | |
| 1000 if (LCA == NULL) { | |
| 1001 // Bailout without retry | |
| 1002 C->record_method_not_compilable("late schedule failed: LCA == NULL"); | |
| 1003 return least; | |
| 1004 } | |
| 1005 | |
| 1006 // Don't hoist machine instructions to the root basic block | |
| 1007 if (mach && LCA == root_block) | |
| 1008 break; | |
| 1009 | |
| 1010 uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
| 1011 uint end_idx = LCA->end_idx(); | |
| 1012 uint end_lat = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx); | |
| 1013 double LCA_freq = LCA->_freq; | |
| 1014 #ifndef PRODUCT | |
| 1015 if (trace_opto_pipelining()) { | |
| 1016 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
| 1017 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq); | |
| 1018 } | |
| 1019 #endif | |
| 1020 if (LCA_freq < least_freq || // Better Frequency | |
| 1021 ( !in_latency && // No block containing latency | |
| 1022 LCA_freq < least_freq * delta && // No worse frequency | |
| 1023 target >= end_lat && // within latency range | |
| 1024 !self->is_iteratively_computed() ) // But don't hoist IV increments | |
| 1025 // because they may end up above other uses of their phi forcing | |
| 1026 // their result register to be different from their input. | |
| 1027 ) { | |
| 1028 least = LCA; // Found cheaper block | |
| 1029 least_freq = LCA_freq; | |
| 1030 start_latency = start_lat; | |
| 1031 end_latency = end_lat; | |
| 1032 if (target <= start_lat) | |
| 1033 in_latency = true; | |
| 1034 } | |
| 1035 } | |
| 1036 | |
| 1037 #ifndef PRODUCT | |
| 1038 if (trace_opto_pipelining()) { | |
| 1039 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g", | |
| 1040 least->_pre_order, start_latency, least_freq); | |
| 1041 } | |
| 1042 #endif | |
| 1043 | |
| 1044 // See if the latency needs to be updated | |
| 1045 if (target < end_latency) { | |
| 1046 #ifndef PRODUCT | |
| 1047 if (trace_opto_pipelining()) { | |
| 1048 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency); | |
| 1049 } | |
| 1050 #endif | |
| 1051 _node_latency.at_put_grow(self->_idx, end_latency); | |
| 1052 partial_latency_of_defs(self); | |
| 1053 } | |
| 1054 | |
| 1055 return least; | |
| 1056 } | |
| 1057 | |
| 1058 | |
| 1059 //------------------------------schedule_late----------------------------------- | |
| 1060 // Now schedule all codes as LATE as possible. This is the LCA in the | |
| 1061 // dominator tree of all USES of a value. Pick the block with the least | |
| 1062 // loop nesting depth that is lowest in the dominator tree. | |
| 1063 extern const char must_clone[]; | |
| 1064 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) { | |
| 1065 #ifndef PRODUCT | |
| 1066 if (trace_opto_pipelining()) | |
| 1067 tty->print("\n#---- schedule_late ----\n"); | |
| 1068 #endif | |
| 1069 | |
| 1070 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
| 1071 Node *self; | |
| 1072 | |
| 1073 // Walk over all the nodes from last to first | |
| 1074 while (self = iter.next()) { | |
| 1075 Block* early = _bbs[self->_idx]; // Earliest legal placement | |
| 1076 | |
| 1077 if (self->is_top()) { | |
| 1078 // Top node goes in bb #2 with other constants. | |
| 1079 // It must be special-cased, because it has no out edges. | |
| 1080 early->add_inst(self); | |
| 1081 continue; | |
| 1082 } | |
| 1083 | |
| 1084 // No uses, just terminate | |
| 1085 if (self->outcnt() == 0) { | |
| 1086 assert(self->Opcode() == Op_MachProj, "sanity"); | |
| 1087 continue; // Must be a dead machine projection | |
| 1088 } | |
| 1089 | |
| 1090 // If node is pinned in the block, then no scheduling can be done. | |
| 1091 if( self->pinned() ) // Pinned in block? | |
| 1092 continue; | |
| 1093 | |
| 1094 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
| 1095 if (mach) { | |
| 1096 switch (mach->ideal_Opcode()) { | |
| 1097 case Op_CreateEx: | |
| 1098 // Don't move exception creation | |
| 1099 early->add_inst(self); | |
| 1100 continue; | |
| 1101 break; | |
| 1102 case Op_CheckCastPP: | |
| 1103 // Don't move CheckCastPP nodes away from their input, if the input | |
| 1104 // is a rawptr (5071820). | |
| 1105 Node *def = self->in(1); | |
| 1106 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) { | |
| 1107 early->add_inst(self); | |
| 1108 continue; | |
| 1109 } | |
| 1110 break; | |
| 1111 } | |
| 1112 } | |
| 1113 | |
| 1114 // Gather LCA of all uses | |
| 1115 Block *LCA = NULL; | |
| 1116 { | |
| 1117 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
| 1118 // For all uses, find LCA | |
| 1119 Node* use = self->fast_out(i); | |
| 1120 LCA = raise_LCA_above_use(LCA, use, self, _bbs); | |
| 1121 } | |
| 1122 } // (Hide defs of imax, i from rest of block.) | |
| 1123 | |
| 1124 // Place temps in the block of their use. This isn't a | |
| 1125 // requirement for correctness but it reduces useless | |
| 1126 // interference between temps and other nodes. | |
| 1127 if (mach != NULL && mach->is_MachTemp()) { | |
| 1128 _bbs.map(self->_idx, LCA); | |
| 1129 LCA->add_inst(self); | |
| 1130 continue; | |
| 1131 } | |
| 1132 | |
| 1133 // Check if 'self' could be anti-dependent on memory | |
| 1134 if (self->needs_anti_dependence_check()) { | |
| 1135 // Hoist LCA above possible-defs and insert anti-dependences to | |
| 1136 // defs in new LCA block. | |
| 1137 LCA = insert_anti_dependences(LCA, self); | |
| 1138 } | |
| 1139 | |
| 1140 if (early->_dom_depth > LCA->_dom_depth) { | |
| 1141 // Somehow the LCA has moved above the earliest legal point. | |
| 1142 // (One way this can happen is via memory_early_block.) | |
| 1143 if (C->subsume_loads() == true && !C->failing()) { | |
| 1144 // Retry with subsume_loads == false | |
| 1145 // If this is the first failure, the sentinel string will "stick" | |
| 1146 // to the Compile object, and the C2Compiler will see it and retry. | |
| 1147 C->record_failure(C2Compiler::retry_no_subsuming_loads()); | |
| 1148 } else { | |
| 1149 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth) | |
| 1150 C->record_method_not_compilable("late schedule failed: incorrect graph"); | |
| 1151 } | |
| 1152 return; | |
| 1153 } | |
| 1154 | |
| 1155 // If there is no opportunity to hoist, then we're done. | |
| 1156 bool try_to_hoist = (LCA != early); | |
| 1157 | |
| 1158 // Must clone guys stay next to use; no hoisting allowed. | |
| 1159 // Also cannot hoist guys that alter memory or are otherwise not | |
| 1160 // allocatable (hoisting can make a value live longer, leading to | |
| 1161 // anti and output dependency problems which are normally resolved | |
| 1162 // by the register allocator giving everyone a different register). | |
| 1163 if (mach != NULL && must_clone[mach->ideal_Opcode()]) | |
| 1164 try_to_hoist = false; | |
| 1165 | |
| 1166 Block* late = NULL; | |
| 1167 if (try_to_hoist) { | |
| 1168 // Now find the block with the least execution frequency. | |
| 1169 // Start at the latest schedule and work up to the earliest schedule | |
| 1170 // in the dominator tree. Thus the Node will dominate all its uses. | |
| 1171 late = hoist_to_cheaper_block(LCA, early, self); | |
| 1172 } else { | |
| 1173 // Just use the LCA of the uses. | |
| 1174 late = LCA; | |
| 1175 } | |
| 1176 | |
| 1177 // Put the node into target block | |
| 1178 schedule_node_into_block(self, late); | |
| 1179 | |
| 1180 #ifdef ASSERT | |
| 1181 if (self->needs_anti_dependence_check()) { | |
| 1182 // since precedence edges are only inserted when we're sure they | |
| 1183 // are needed make sure that after placement in a block we don't | |
| 1184 // need any new precedence edges. | |
| 1185 verify_anti_dependences(late, self); | |
| 1186 } | |
| 1187 #endif | |
| 1188 } // Loop until all nodes have been visited | |
| 1189 | |
| 1190 } // end ScheduleLate | |
| 1191 | |
| 1192 //------------------------------GlobalCodeMotion------------------------------- | |
| 1193 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) { | |
| 1194 ResourceMark rm; | |
| 1195 | |
| 1196 #ifndef PRODUCT | |
| 1197 if (trace_opto_pipelining()) { | |
| 1198 tty->print("\n---- Start GlobalCodeMotion ----\n"); | |
| 1199 } | |
| 1200 #endif | |
| 1201 | |
| 1202 // Initialize the bbs.map for things on the proj_list | |
| 1203 uint i; | |
| 1204 for( i=0; i < proj_list.size(); i++ ) | |
| 1205 _bbs.map(proj_list[i]->_idx, NULL); | |
| 1206 | |
| 1207 // Set the basic block for Nodes pinned into blocks | |
| 1208 Arena *a = Thread::current()->resource_area(); | |
| 1209 VectorSet visited(a); | |
| 1210 schedule_pinned_nodes( visited ); | |
| 1211 | |
| 1212 // Find the earliest Block any instruction can be placed in. Some | |
| 1213 // instructions are pinned into Blocks. Unpinned instructions can | |
| 1214 // appear in last block in which all their inputs occur. | |
| 1215 visited.Clear(); | |
| 1216 Node_List stack(a); | |
| 1217 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list | |
| 1218 if (!schedule_early(visited, stack)) { | |
| 1219 // Bailout without retry | |
| 1220 C->record_method_not_compilable("early schedule failed"); | |
| 1221 return; | |
| 1222 } | |
| 1223 | |
| 1224 // Build Def-Use edges. | |
| 1225 proj_list.push(_root); // Add real root as another root | |
| 1226 proj_list.pop(); | |
| 1227 | |
| 1228 // Compute the latency information (via backwards walk) for all the | |
| 1229 // instructions in the graph | |
| 1230 GrowableArray<uint> node_latency; | |
| 1231 _node_latency = node_latency; | |
| 1232 | |
| 1233 if( C->do_scheduling() ) | |
| 1234 ComputeLatenciesBackwards(visited, stack); | |
| 1235 | |
| 1236 // Now schedule all codes as LATE as possible. This is the LCA in the | |
| 1237 // dominator tree of all USES of a value. Pick the block with the least | |
| 1238 // loop nesting depth that is lowest in the dominator tree. | |
| 1239 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() ) | |
| 1240 schedule_late(visited, stack); | |
| 1241 if( C->failing() ) { | |
| 1242 // schedule_late fails only when graph is incorrect. | |
| 1243 assert(!VerifyGraphEdges, "verification should have failed"); | |
| 1244 return; | |
| 1245 } | |
| 1246 | |
| 1247 unique = C->unique(); | |
| 1248 | |
| 1249 #ifndef PRODUCT | |
| 1250 if (trace_opto_pipelining()) { | |
| 1251 tty->print("\n---- Detect implicit null checks ----\n"); | |
| 1252 } | |
| 1253 #endif | |
| 1254 | |
| 1255 // Detect implicit-null-check opportunities. Basically, find NULL checks | |
| 1256 // with suitable memory ops nearby. Use the memory op to do the NULL check. | |
| 1257 // I can generate a memory op if there is not one nearby. | |
| 1258 if (C->is_method_compilation()) { | |
| 1259 // Don't do it for natives, adapters, or runtime stubs | |
| 1260 int allowed_reasons = 0; | |
| 1261 // ...and don't do it when there have been too many traps, globally. | |
| 1262 for (int reason = (int)Deoptimization::Reason_none+1; | |
| 1263 reason < Compile::trapHistLength; reason++) { | |
| 1264 assert(reason < BitsPerInt, "recode bit map"); | |
| 1265 if (!C->too_many_traps((Deoptimization::DeoptReason) reason)) | |
| 1266 allowed_reasons |= nth_bit(reason); | |
| 1267 } | |
| 1268 // By reversing the loop direction we get a very minor gain on mpegaudio. | |
| 1269 // Feel free to revert to a forward loop for clarity. | |
| 1270 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) { | |
| 1271 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) { | |
| 1272 Node *proj = matcher._null_check_tests[i ]; | |
| 1273 Node *val = matcher._null_check_tests[i+1]; | |
| 1274 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons); | |
| 1275 // The implicit_null_check will only perform the transformation | |
| 1276 // if the null branch is truly uncommon, *and* it leads to an | |
| 1277 // uncommon trap. Combined with the too_many_traps guards | |
| 1278 // above, this prevents SEGV storms reported in 6366351, | |
| 1279 // by recompiling offending methods without this optimization. | |
| 1280 } | |
| 1281 } | |
| 1282 | |
| 1283 #ifndef PRODUCT | |
| 1284 if (trace_opto_pipelining()) { | |
| 1285 tty->print("\n---- Start Local Scheduling ----\n"); | |
| 1286 } | |
| 1287 #endif | |
| 1288 | |
| 1289 // Schedule locally. Right now a simple topological sort. | |
| 1290 // Later, do a real latency aware scheduler. | |
| 1291 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique()); | |
| 1292 memset( ready_cnt, -1, C->unique() * sizeof(int) ); | |
| 1293 visited.Clear(); | |
| 1294 for (i = 0; i < _num_blocks; i++) { | |
| 1295 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) { | |
| 1296 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { | |
| 1297 C->record_method_not_compilable("local schedule failed"); | |
| 1298 } | |
| 1299 return; | |
| 1300 } | |
| 1301 } | |
| 1302 | |
| 1303 // If we inserted any instructions between a Call and his CatchNode, | |
| 1304 // clone the instructions on all paths below the Catch. | |
| 1305 for( i=0; i < _num_blocks; i++ ) | |
| 1306 _blocks[i]->call_catch_cleanup(_bbs); | |
| 1307 | |
| 1308 #ifndef PRODUCT | |
| 1309 if (trace_opto_pipelining()) { | |
| 1310 tty->print("\n---- After GlobalCodeMotion ----\n"); | |
| 1311 for (uint i = 0; i < _num_blocks; i++) { | |
| 1312 _blocks[i]->dump(); | |
| 1313 } | |
| 1314 } | |
| 1315 #endif | |
| 1316 } | |
| 1317 | |
| 1318 | |
| 1319 //------------------------------Estimate_Block_Frequency----------------------- | |
| 1320 // Estimate block frequencies based on IfNode probabilities. | |
| 1321 void PhaseCFG::Estimate_Block_Frequency() { | |
| 1322 int cnts = C->method() ? C->method()->interpreter_invocation_count() : 1; | |
| 1323 // Most of our algorithms will die horribly if frequency can become | |
| 1324 // negative so make sure cnts is a sane value. | |
| 1325 if( cnts <= 0 ) cnts = 1; | |
| 1326 float f = (float)cnts/(float)FreqCountInvocations; | |
| 1327 | |
| 1328 // Create the loop tree and calculate loop depth. | |
| 1329 _root_loop = create_loop_tree(); | |
| 1330 _root_loop->compute_loop_depth(0); | |
| 1331 | |
| 1332 // Compute block frequency of each block, relative to a single loop entry. | |
| 1333 _root_loop->compute_freq(); | |
| 1334 | |
| 1335 // Adjust all frequencies to be relative to a single method entry | |
| 1336 _root_loop->_freq = f * 1.0; | |
| 1337 _root_loop->scale_freq(); | |
| 1338 | |
| 1339 // force paths ending at uncommon traps to be infrequent | |
| 1340 Block_List worklist; | |
| 1341 Block* root_blk = _blocks[0]; | |
| 1342 for (uint i = 0; i < root_blk->num_preds(); i++) { | |
| 1343 Block *pb = _bbs[root_blk->pred(i)->_idx]; | |
| 1344 if (pb->has_uncommon_code()) { | |
| 1345 worklist.push(pb); | |
| 1346 } | |
| 1347 } | |
| 1348 while (worklist.size() > 0) { | |
| 1349 Block* uct = worklist.pop(); | |
| 1350 uct->_freq = PROB_MIN; | |
| 1351 for (uint i = 0; i < uct->num_preds(); i++) { | |
| 1352 Block *pb = _bbs[uct->pred(i)->_idx]; | |
| 1353 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { | |
| 1354 worklist.push(pb); | |
| 1355 } | |
| 1356 } | |
| 1357 } | |
| 1358 | |
| 1359 #ifndef PRODUCT | |
| 1360 if (PrintCFGBlockFreq) { | |
| 1361 tty->print_cr("CFG Block Frequencies"); | |
| 1362 _root_loop->dump_tree(); | |
| 1363 if (Verbose) { | |
| 1364 tty->print_cr("PhaseCFG dump"); | |
| 1365 dump(); | |
| 1366 tty->print_cr("Node dump"); | |
| 1367 _root->dump(99999); | |
| 1368 } | |
| 1369 } | |
| 1370 #endif | |
| 1371 } | |
| 1372 | |
| 1373 //----------------------------create_loop_tree-------------------------------- | |
| 1374 // Create a loop tree from the CFG | |
| 1375 CFGLoop* PhaseCFG::create_loop_tree() { | |
| 1376 | |
| 1377 #ifdef ASSERT | |
| 1378 assert( _blocks[0] == _broot, "" ); | |
| 1379 for (uint i = 0; i < _num_blocks; i++ ) { | |
| 1380 Block *b = _blocks[i]; | |
| 1381 // Check that _loop field are clear...we could clear them if not. | |
| 1382 assert(b->_loop == NULL, "clear _loop expected"); | |
| 1383 // Sanity check that the RPO numbering is reflected in the _blocks array. | |
| 1384 // It doesn't have to be for the loop tree to be built, but if it is not, | |
| 1385 // then the blocks have been reordered since dom graph building...which | |
| 1386 // may question the RPO numbering | |
| 1387 assert(b->_rpo == i, "unexpected reverse post order number"); | |
| 1388 } | |
| 1389 #endif | |
| 1390 | |
| 1391 int idct = 0; | |
| 1392 CFGLoop* root_loop = new CFGLoop(idct++); | |
| 1393 | |
| 1394 Block_List worklist; | |
| 1395 | |
| 1396 // Assign blocks to loops | |
| 1397 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block | |
| 1398 Block *b = _blocks[i]; | |
| 1399 | |
| 1400 if (b->head()->is_Loop()) { | |
| 1401 Block* loop_head = b; | |
| 1402 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
| 1403 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); | |
| 1404 Block* tail = _bbs[tail_n->_idx]; | |
| 1405 | |
| 1406 // Defensively filter out Loop nodes for non-single-entry loops. | |
| 1407 // For all reasonable loops, the head occurs before the tail in RPO. | |
| 1408 if (i <= tail->_rpo) { | |
| 1409 | |
| 1410 // The tail and (recursive) predecessors of the tail | |
| 1411 // are made members of a new loop. | |
| 1412 | |
| 1413 assert(worklist.size() == 0, "nonempty worklist"); | |
| 1414 CFGLoop* nloop = new CFGLoop(idct++); | |
| 1415 assert(loop_head->_loop == NULL, "just checking"); | |
| 1416 loop_head->_loop = nloop; | |
| 1417 // Add to nloop so push_pred() will skip over inner loops | |
| 1418 nloop->add_member(loop_head); | |
| 1419 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs); | |
| 1420 | |
| 1421 while (worklist.size() > 0) { | |
| 1422 Block* member = worklist.pop(); | |
| 1423 if (member != loop_head) { | |
| 1424 for (uint j = 1; j < member->num_preds(); j++) { | |
| 1425 nloop->push_pred(member, j, worklist, _bbs); | |
| 1426 } | |
| 1427 } | |
| 1428 } | |
| 1429 } | |
| 1430 } | |
| 1431 } | |
| 1432 | |
| 1433 // Create a member list for each loop consisting | |
| 1434 // of both blocks and (immediate child) loops. | |
| 1435 for (uint i = 0; i < _num_blocks; i++) { | |
| 1436 Block *b = _blocks[i]; | |
| 1437 CFGLoop* lp = b->_loop; | |
| 1438 if (lp == NULL) { | |
| 1439 // Not assigned to a loop. Add it to the method's pseudo loop. | |
| 1440 b->_loop = root_loop; | |
| 1441 lp = root_loop; | |
| 1442 } | |
| 1443 if (lp == root_loop || b != lp->head()) { // loop heads are already members | |
| 1444 lp->add_member(b); | |
| 1445 } | |
| 1446 if (lp != root_loop) { | |
| 1447 if (lp->parent() == NULL) { | |
| 1448 // Not a nested loop. Make it a child of the method's pseudo loop. | |
| 1449 root_loop->add_nested_loop(lp); | |
| 1450 } | |
| 1451 if (b == lp->head()) { | |
| 1452 // Add nested loop to member list of parent loop. | |
| 1453 lp->parent()->add_member(lp); | |
| 1454 } | |
| 1455 } | |
| 1456 } | |
| 1457 | |
| 1458 return root_loop; | |
| 1459 } | |
| 1460 | |
| 1461 //------------------------------push_pred-------------------------------------- | |
| 1462 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) { | |
| 1463 Node* pred_n = blk->pred(i); | |
| 1464 Block* pred = node_to_blk[pred_n->_idx]; | |
| 1465 CFGLoop *pred_loop = pred->_loop; | |
| 1466 if (pred_loop == NULL) { | |
| 1467 // Filter out blocks for non-single-entry loops. | |
| 1468 // For all reasonable loops, the head occurs before the tail in RPO. | |
| 1469 if (pred->_rpo > head()->_rpo) { | |
| 1470 pred->_loop = this; | |
| 1471 worklist.push(pred); | |
| 1472 } | |
| 1473 } else if (pred_loop != this) { | |
| 1474 // Nested loop. | |
| 1475 while (pred_loop->_parent != NULL && pred_loop->_parent != this) { | |
| 1476 pred_loop = pred_loop->_parent; | |
| 1477 } | |
| 1478 // Make pred's loop be a child | |
| 1479 if (pred_loop->_parent == NULL) { | |
| 1480 add_nested_loop(pred_loop); | |
| 1481 // Continue with loop entry predecessor. | |
| 1482 Block* pred_head = pred_loop->head(); | |
| 1483 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
| 1484 assert(pred_head != head(), "loop head in only one loop"); | |
| 1485 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk); | |
| 1486 } else { | |
| 1487 assert(pred_loop->_parent == this && _parent == NULL, "just checking"); | |
| 1488 } | |
| 1489 } | |
| 1490 } | |
| 1491 | |
| 1492 //------------------------------add_nested_loop-------------------------------- | |
| 1493 // Make cl a child of the current loop in the loop tree. | |
| 1494 void CFGLoop::add_nested_loop(CFGLoop* cl) { | |
| 1495 assert(_parent == NULL, "no parent yet"); | |
| 1496 assert(cl != this, "not my own parent"); | |
| 1497 cl->_parent = this; | |
| 1498 CFGLoop* ch = _child; | |
| 1499 if (ch == NULL) { | |
| 1500 _child = cl; | |
| 1501 } else { | |
| 1502 while (ch->_sibling != NULL) { ch = ch->_sibling; } | |
| 1503 ch->_sibling = cl; | |
| 1504 } | |
| 1505 } | |
| 1506 | |
| 1507 //------------------------------compute_loop_depth----------------------------- | |
| 1508 // Store the loop depth in each CFGLoop object. | |
| 1509 // Recursively walk the children to do the same for them. | |
| 1510 void CFGLoop::compute_loop_depth(int depth) { | |
| 1511 _depth = depth; | |
| 1512 CFGLoop* ch = _child; | |
| 1513 while (ch != NULL) { | |
| 1514 ch->compute_loop_depth(depth + 1); | |
| 1515 ch = ch->_sibling; | |
| 1516 } | |
| 1517 } | |
| 1518 | |
| 1519 //------------------------------compute_freq----------------------------------- | |
| 1520 // Compute the frequency of each block and loop, relative to a single entry | |
| 1521 // into the dominating loop head. | |
| 1522 void CFGLoop::compute_freq() { | |
| 1523 // Bottom up traversal of loop tree (visit inner loops first.) | |
| 1524 // Set loop head frequency to 1.0, then transitively | |
| 1525 // compute frequency for all successors in the loop, | |
| 1526 // as well as for each exit edge. Inner loops are | |
| 1527 // treated as single blocks with loop exit targets | |
| 1528 // as the successor blocks. | |
| 1529 | |
| 1530 // Nested loops first | |
| 1531 CFGLoop* ch = _child; | |
| 1532 while (ch != NULL) { | |
| 1533 ch->compute_freq(); | |
| 1534 ch = ch->_sibling; | |
| 1535 } | |
| 1536 assert (_members.length() > 0, "no empty loops"); | |
| 1537 Block* hd = head(); | |
| 1538 hd->_freq = 1.0f; | |
| 1539 for (int i = 0; i < _members.length(); i++) { | |
| 1540 CFGElement* s = _members.at(i); | |
| 1541 float freq = s->_freq; | |
| 1542 if (s->is_block()) { | |
| 1543 Block* b = s->as_Block(); | |
| 1544 for (uint j = 0; j < b->_num_succs; j++) { | |
| 1545 Block* sb = b->_succs[j]; | |
| 1546 update_succ_freq(sb, freq * b->succ_prob(j)); | |
| 1547 } | |
| 1548 } else { | |
| 1549 CFGLoop* lp = s->as_CFGLoop(); | |
| 1550 assert(lp->_parent == this, "immediate child"); | |
| 1551 for (int k = 0; k < lp->_exits.length(); k++) { | |
| 1552 Block* eb = lp->_exits.at(k).get_target(); | |
| 1553 float prob = lp->_exits.at(k).get_prob(); | |
| 1554 update_succ_freq(eb, freq * prob); | |
| 1555 } | |
| 1556 } | |
| 1557 } | |
| 1558 | |
| 1559 #if 0 | |
| 1560 // Raise frequency of the loop backedge block, in an effort | |
| 1561 // to keep it empty. Skip the method level "loop". | |
| 1562 if (_parent != NULL) { | |
| 1563 CFGElement* s = _members.at(_members.length() - 1); | |
| 1564 if (s->is_block()) { | |
| 1565 Block* bk = s->as_Block(); | |
| 1566 if (bk->_num_succs == 1 && bk->_succs[0] == hd) { | |
| 1567 // almost any value >= 1.0f works | |
| 1568 // FIXME: raw constant | |
| 1569 bk->_freq = 1.05f; | |
| 1570 } | |
| 1571 } | |
| 1572 } | |
| 1573 #endif | |
| 1574 | |
| 1575 // For all loops other than the outer, "method" loop, | |
| 1576 // sum and normalize the exit probability. The "method" loop | |
| 1577 // should keep the initial exit probability of 1, so that | |
| 1578 // inner blocks do not get erroneously scaled. | |
| 1579 if (_depth != 0) { | |
| 1580 // Total the exit probabilities for this loop. | |
| 1581 float exits_sum = 0.0f; | |
| 1582 for (int i = 0; i < _exits.length(); i++) { | |
| 1583 exits_sum += _exits.at(i).get_prob(); | |
| 1584 } | |
| 1585 | |
| 1586 // Normalize the exit probabilities. Until now, the | |
| 1587 // probabilities estimate the possibility of exit per | |
| 1588 // a single loop iteration; afterward, they estimate | |
| 1589 // the probability of exit per loop entry. | |
| 1590 for (int i = 0; i < _exits.length(); i++) { | |
| 1591 Block* et = _exits.at(i).get_target(); | |
| 1592 float new_prob = _exits.at(i).get_prob() / exits_sum; | |
| 1593 BlockProbPair bpp(et, new_prob); | |
| 1594 _exits.at_put(i, bpp); | |
| 1595 } | |
| 1596 | |
| 1597 // Save the total, but guard against unreasoable probability, | |
| 1598 // as the value is used to estimate the loop trip count. | |
| 1599 // An infinite trip count would blur relative block | |
| 1600 // frequencies. | |
| 1601 if (exits_sum > 1.0f) exits_sum = 1.0; | |
| 1602 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN; | |
| 1603 _exit_prob = exits_sum; | |
| 1604 } | |
| 1605 } | |
| 1606 | |
| 1607 //------------------------------succ_prob------------------------------------- | |
| 1608 // Determine the probability of reaching successor 'i' from the receiver block. | |
| 1609 float Block::succ_prob(uint i) { | |
| 1610 int eidx = end_idx(); | |
| 1611 Node *n = _nodes[eidx]; // Get ending Node | |
| 1612 int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode(); | |
| 1613 | |
| 1614 // Switch on branch type | |
| 1615 switch( op ) { | |
| 1616 case Op_CountedLoopEnd: | |
| 1617 case Op_If: { | |
| 1618 assert (i < 2, "just checking"); | |
| 1619 // Conditionals pass on only part of their frequency | |
| 1620 float prob = n->as_MachIf()->_prob; | |
| 1621 assert(prob >= 0.0 && prob <= 1.0, "out of range probability"); | |
| 1622 // If succ[i] is the FALSE branch, invert path info | |
| 1623 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) { | |
| 1624 return 1.0f - prob; // not taken | |
| 1625 } else { | |
| 1626 return prob; // taken | |
| 1627 } | |
| 1628 } | |
| 1629 | |
| 1630 case Op_Jump: | |
| 1631 // Divide the frequency between all successors evenly | |
| 1632 return 1.0f/_num_succs; | |
| 1633 | |
| 1634 case Op_Catch: { | |
| 1635 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); | |
| 1636 if (ci->_con == CatchProjNode::fall_through_index) { | |
| 1637 // Fall-thru path gets the lion's share. | |
| 1638 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs; | |
| 1639 } else { | |
| 1640 // Presume exceptional paths are equally unlikely | |
| 1641 return PROB_UNLIKELY_MAG(5); | |
| 1642 } | |
| 1643 } | |
| 1644 | |
| 1645 case Op_Root: | |
| 1646 case Op_Goto: | |
| 1647 // Pass frequency straight thru to target | |
| 1648 return 1.0f; | |
| 1649 | |
| 1650 case Op_NeverBranch: | |
| 1651 return 0.0f; | |
| 1652 | |
| 1653 case Op_TailCall: | |
| 1654 case Op_TailJump: | |
| 1655 case Op_Return: | |
| 1656 case Op_Halt: | |
| 1657 case Op_Rethrow: | |
| 1658 // Do not push out freq to root block | |
| 1659 return 0.0f; | |
| 1660 | |
| 1661 default: | |
| 1662 ShouldNotReachHere(); | |
| 1663 } | |
| 1664 | |
| 1665 return 0.0f; | |
| 1666 } | |
| 1667 | |
| 1668 //------------------------------update_succ_freq------------------------------- | |
| 1669 // Update the appropriate frequency associated with block 'b', a succesor of | |
| 1670 // a block in this loop. | |
| 1671 void CFGLoop::update_succ_freq(Block* b, float freq) { | |
| 1672 if (b->_loop == this) { | |
| 1673 if (b == head()) { | |
| 1674 // back branch within the loop | |
| 1675 // Do nothing now, the loop carried frequency will be | |
| 1676 // adjust later in scale_freq(). | |
| 1677 } else { | |
| 1678 // simple branch within the loop | |
| 1679 b->_freq += freq; | |
| 1680 } | |
| 1681 } else if (!in_loop_nest(b)) { | |
| 1682 // branch is exit from this loop | |
| 1683 BlockProbPair bpp(b, freq); | |
| 1684 _exits.append(bpp); | |
| 1685 } else { | |
| 1686 // branch into nested loop | |
| 1687 CFGLoop* ch = b->_loop; | |
| 1688 ch->_freq += freq; | |
| 1689 } | |
| 1690 } | |
| 1691 | |
| 1692 //------------------------------in_loop_nest----------------------------------- | |
| 1693 // Determine if block b is in the receiver's loop nest. | |
| 1694 bool CFGLoop::in_loop_nest(Block* b) { | |
| 1695 int depth = _depth; | |
| 1696 CFGLoop* b_loop = b->_loop; | |
| 1697 int b_depth = b_loop->_depth; | |
| 1698 if (depth == b_depth) { | |
| 1699 return true; | |
| 1700 } | |
| 1701 while (b_depth > depth) { | |
| 1702 b_loop = b_loop->_parent; | |
| 1703 b_depth = b_loop->_depth; | |
| 1704 } | |
| 1705 return b_loop == this; | |
| 1706 } | |
| 1707 | |
| 1708 //------------------------------scale_freq------------------------------------- | |
| 1709 // Scale frequency of loops and blocks by trip counts from outer loops | |
| 1710 // Do a top down traversal of loop tree (visit outer loops first.) | |
| 1711 void CFGLoop::scale_freq() { | |
| 1712 float loop_freq = _freq * trip_count(); | |
| 1713 for (int i = 0; i < _members.length(); i++) { | |
| 1714 CFGElement* s = _members.at(i); | |
| 1715 s->_freq *= loop_freq; | |
| 1716 } | |
| 1717 CFGLoop* ch = _child; | |
| 1718 while (ch != NULL) { | |
| 1719 ch->scale_freq(); | |
| 1720 ch = ch->_sibling; | |
| 1721 } | |
| 1722 } | |
| 1723 | |
| 1724 #ifndef PRODUCT | |
| 1725 //------------------------------dump_tree-------------------------------------- | |
| 1726 void CFGLoop::dump_tree() const { | |
| 1727 dump(); | |
| 1728 if (_child != NULL) _child->dump_tree(); | |
| 1729 if (_sibling != NULL) _sibling->dump_tree(); | |
| 1730 } | |
| 1731 | |
| 1732 //------------------------------dump------------------------------------------- | |
| 1733 void CFGLoop::dump() const { | |
| 1734 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1735 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n", | |
| 1736 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq); | |
| 1737 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1738 tty->print(" members:", _id); | |
| 1739 int k = 0; | |
| 1740 for (int i = 0; i < _members.length(); i++) { | |
| 1741 if (k++ >= 6) { | |
| 1742 tty->print("\n "); | |
| 1743 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
| 1744 k = 0; | |
| 1745 } | |
| 1746 CFGElement *s = _members.at(i); | |
| 1747 if (s->is_block()) { | |
| 1748 Block *b = s->as_Block(); | |
| 1749 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq); | |
| 1750 } else { | |
| 1751 CFGLoop* lp = s->as_CFGLoop(); | |
| 1752 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq); | |
| 1753 } | |
| 1754 } | |
| 1755 tty->print("\n"); | |
| 1756 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1757 tty->print(" exits: "); | |
| 1758 k = 0; | |
| 1759 for (int i = 0; i < _exits.length(); i++) { | |
| 1760 if (k++ >= 7) { | |
| 1761 tty->print("\n "); | |
| 1762 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
| 1763 k = 0; | |
| 1764 } | |
| 1765 Block *blk = _exits.at(i).get_target(); | |
| 1766 float prob = _exits.at(i).get_prob(); | |
| 1767 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); | |
| 1768 } | |
| 1769 tty->print("\n"); | |
| 1770 } | |
| 1771 #endif |