Mercurial > hg > truffle
annotate src/share/vm/opto/gcm.cpp @ 628:7bb995fbd3c0
Merge
| author | trims |
|---|---|
| date | Thu, 12 Mar 2009 18:16:36 -0700 |
| parents | 0fbdb4381b99 19f25e603e7b |
| children | fbc12e71c476 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 579 | 2 * Copyright 1997-2009 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 | |
|
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32 // To avoid float value underflow |
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33 #define MIN_BLOCK_FREQUENCY 1.e-35f |
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34 |
| 0 | 35 //----------------------------schedule_node_into_block------------------------- |
| 36 // Insert node n into block b. Look for projections of n and make sure they | |
| 37 // are in b also. | |
| 38 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) { | |
| 39 // Set basic block of n, Add n to b, | |
| 40 _bbs.map(n->_idx, b); | |
| 41 b->add_inst(n); | |
| 42 | |
| 43 // After Matching, nearly any old Node may have projections trailing it. | |
| 44 // These are usually machine-dependent flags. In any case, they might | |
| 45 // float to another block below this one. Move them up. | |
| 46 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
| 47 Node* use = n->fast_out(i); | |
| 48 if (use->is_Proj()) { | |
| 49 Block* buse = _bbs[use->_idx]; | |
| 50 if (buse != b) { // In wrong block? | |
| 51 if (buse != NULL) | |
| 52 buse->find_remove(use); // Remove from wrong block | |
| 53 _bbs.map(use->_idx, b); // Re-insert in this block | |
| 54 b->add_inst(use); | |
| 55 } | |
| 56 } | |
| 57 } | |
| 58 } | |
| 59 | |
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60 //----------------------------replace_block_proj_ctrl------------------------- |
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61 // Nodes that have is_block_proj() nodes as their control need to use |
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62 // the appropriate Region for their actual block as their control since |
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63 // the projection will be in a predecessor block. |
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64 void PhaseCFG::replace_block_proj_ctrl( Node *n ) { |
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65 const Node *in0 = n->in(0); |
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66 assert(in0 != NULL, "Only control-dependent"); |
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67 const Node *p = in0->is_block_proj(); |
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68 if (p != NULL && p != n) { // Control from a block projection? |
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69 assert(!n->pinned() || n->is_SafePointScalarObject(), "only SafePointScalarObject pinned node is expected here"); |
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70 // Find trailing Region |
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71 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block |
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72 uint j = 0; |
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73 if (pb->_num_succs != 1) { // More then 1 successor? |
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74 // Search for successor |
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75 uint max = pb->_nodes.size(); |
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76 assert( max > 1, "" ); |
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77 uint start = max - pb->_num_succs; |
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78 // Find which output path belongs to projection |
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79 for (j = start; j < max; j++) { |
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80 if( pb->_nodes[j] == in0 ) |
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81 break; |
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82 } |
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83 assert( j < max, "must find" ); |
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84 // Change control to match head of successor basic block |
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85 j -= start; |
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86 } |
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87 n->set_req(0, pb->_succs[j]->head()); |
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88 } |
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89 } |
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90 |
| 0 | 91 |
| 92 //------------------------------schedule_pinned_nodes-------------------------- | |
| 93 // Set the basic block for Nodes pinned into blocks | |
| 94 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) { | |
| 95 // Allocate node stack of size C->unique()+8 to avoid frequent realloc | |
| 96 GrowableArray <Node *> spstack(C->unique()+8); | |
| 97 spstack.push(_root); | |
| 98 while ( spstack.is_nonempty() ) { | |
| 99 Node *n = spstack.pop(); | |
| 100 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited | |
| 101 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down! | |
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102 assert( n->in(0), "pinned Node must have Control" ); |
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103 // Before setting block replace block_proj control edge |
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104 replace_block_proj_ctrl(n); |
| 0 | 105 Node *input = n->in(0); |
| 106 while( !input->is_block_start() ) | |
| 107 input = input->in(0); | |
| 108 Block *b = _bbs[input->_idx]; // Basic block of controlling input | |
| 109 schedule_node_into_block(n, b); | |
| 110 } | |
| 111 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs | |
| 112 if( n->in(i) != NULL ) | |
| 113 spstack.push(n->in(i)); | |
| 114 } | |
| 115 } | |
| 116 } | |
| 117 } | |
| 118 | |
| 119 #ifdef ASSERT | |
| 120 // Assert that new input b2 is dominated by all previous inputs. | |
| 121 // Check this by by seeing that it is dominated by b1, the deepest | |
| 122 // input observed until b2. | |
| 123 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) { | |
| 124 if (b1 == NULL) return; | |
| 125 assert(b1->_dom_depth < b2->_dom_depth, "sanity"); | |
| 126 Block* tmp = b2; | |
| 127 while (tmp != b1 && tmp != NULL) { | |
| 128 tmp = tmp->_idom; | |
| 129 } | |
| 130 if (tmp != b1) { | |
| 131 // Detected an unschedulable graph. Print some nice stuff and die. | |
| 132 tty->print_cr("!!! Unschedulable graph !!!"); | |
| 133 for (uint j=0; j<n->len(); j++) { // For all inputs | |
| 134 Node* inn = n->in(j); // Get input | |
| 135 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
| 136 Block* inb = bbs[inn->_idx]; | |
| 137 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order, | |
| 138 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth); | |
| 139 inn->dump(); | |
| 140 } | |
| 141 tty->print("Failing node: "); | |
| 142 n->dump(); | |
| 143 assert(false, "unscheduable graph"); | |
| 144 } | |
| 145 } | |
| 146 #endif | |
| 147 | |
| 148 static Block* find_deepest_input(Node* n, Block_Array &bbs) { | |
| 149 // Find the last input dominated by all other inputs. | |
| 150 Block* deepb = NULL; // Deepest block so far | |
| 151 int deepb_dom_depth = 0; | |
| 152 for (uint k = 0; k < n->len(); k++) { // For all inputs | |
| 153 Node* inn = n->in(k); // Get input | |
| 154 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
| 155 Block* inb = bbs[inn->_idx]; | |
| 156 assert(inb != NULL, "must already have scheduled this input"); | |
| 157 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
| 158 // The new inb must be dominated by the previous deepb. | |
| 159 // The various inputs must be linearly ordered in the dom | |
| 160 // tree, or else there will not be a unique deepest block. | |
| 161 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs)); | |
| 162 deepb = inb; // Save deepest block | |
| 163 deepb_dom_depth = deepb->_dom_depth; | |
| 164 } | |
| 165 } | |
| 166 assert(deepb != NULL, "must be at least one input to n"); | |
| 167 return deepb; | |
| 168 } | |
| 169 | |
| 170 | |
| 171 //------------------------------schedule_early--------------------------------- | |
| 172 // Find the earliest Block any instruction can be placed in. Some instructions | |
| 173 // are pinned into Blocks. Unpinned instructions can appear in last block in | |
| 174 // which all their inputs occur. | |
| 175 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) { | |
| 176 // Allocate stack with enough space to avoid frequent realloc | |
| 177 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats | |
| 178 // roots.push(_root); _root will be processed among C->top() inputs | |
| 179 roots.push(C->top()); | |
| 180 visited.set(C->top()->_idx); | |
| 181 | |
| 182 while (roots.size() != 0) { | |
| 183 // Use local variables nstack_top_n & nstack_top_i to cache values | |
| 184 // on stack's top. | |
| 185 Node *nstack_top_n = roots.pop(); | |
| 186 uint nstack_top_i = 0; | |
| 187 //while_nstack_nonempty: | |
| 188 while (true) { | |
| 189 // Get parent node and next input's index from stack's top. | |
| 190 Node *n = nstack_top_n; | |
| 191 uint i = nstack_top_i; | |
| 192 | |
| 193 if (i == 0) { | |
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194 // Fixup some control. Constants without control get attached |
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195 // to root and nodes that use is_block_proj() nodes should be attached |
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196 // to the region that starts their block. |
| 0 | 197 const Node *in0 = n->in(0); |
| 198 if (in0 != NULL) { // Control-dependent? | |
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199 replace_block_proj_ctrl(n); |
| 0 | 200 } else { // n->in(0) == NULL |
| 201 if (n->req() == 1) { // This guy is a constant with NO inputs? | |
| 202 n->set_req(0, _root); | |
| 203 } | |
| 204 } | |
| 205 } | |
| 206 | |
| 207 // First, visit all inputs and force them to get a block. If an | |
| 208 // input is already in a block we quit following inputs (to avoid | |
| 209 // cycles). Instead we put that Node on a worklist to be handled | |
| 210 // later (since IT'S inputs may not have a block yet). | |
| 211 bool done = true; // Assume all n's inputs will be processed | |
| 212 while (i < n->len()) { // For all inputs | |
| 213 Node *in = n->in(i); // Get input | |
| 214 ++i; | |
| 215 if (in == NULL) continue; // Ignore NULL, missing inputs | |
| 216 int is_visited = visited.test_set(in->_idx); | |
| 217 if (!_bbs.lookup(in->_idx)) { // Missing block selection? | |
| 218 if (is_visited) { | |
| 219 // assert( !visited.test(in->_idx), "did not schedule early" ); | |
| 220 return false; | |
| 221 } | |
| 222 nstack.push(n, i); // Save parent node and next input's index. | |
| 223 nstack_top_n = in; // Process current input now. | |
| 224 nstack_top_i = 0; | |
| 225 done = false; // Not all n's inputs processed. | |
| 226 break; // continue while_nstack_nonempty; | |
| 227 } else if (!is_visited) { // Input not yet visited? | |
| 228 roots.push(in); // Visit this guy later, using worklist | |
| 229 } | |
| 230 } | |
| 231 if (done) { | |
| 232 // All of n's inputs have been processed, complete post-processing. | |
| 233 | |
| 234 // Some instructions are pinned into a block. These include Region, | |
| 235 // Phi, Start, Return, and other control-dependent instructions and | |
| 236 // any projections which depend on them. | |
| 237 if (!n->pinned()) { | |
| 238 // Set earliest legal block. | |
| 239 _bbs.map(n->_idx, find_deepest_input(n, _bbs)); | |
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240 } else { |
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241 assert(_bbs[n->_idx] == _bbs[n->in(0)->_idx], "Pinned Node should be at the same block as its control edge"); |
| 0 | 242 } |
| 243 | |
| 244 if (nstack.is_empty()) { | |
| 245 // Finished all nodes on stack. | |
| 246 // Process next node on the worklist 'roots'. | |
| 247 break; | |
| 248 } | |
| 249 // Get saved parent node and next input's index. | |
| 250 nstack_top_n = nstack.node(); | |
| 251 nstack_top_i = nstack.index(); | |
| 252 nstack.pop(); | |
| 253 } // if (done) | |
| 254 } // while (true) | |
| 255 } // while (roots.size() != 0) | |
| 256 return true; | |
| 257 } | |
| 258 | |
| 259 //------------------------------dom_lca---------------------------------------- | |
| 260 // Find least common ancestor in dominator tree | |
| 261 // LCA is a current notion of LCA, to be raised above 'this'. | |
| 262 // As a convenient boundary condition, return 'this' if LCA is NULL. | |
| 263 // Find the LCA of those two nodes. | |
| 264 Block* Block::dom_lca(Block* LCA) { | |
| 265 if (LCA == NULL || LCA == this) return this; | |
| 266 | |
| 267 Block* anc = this; | |
| 268 while (anc->_dom_depth > LCA->_dom_depth) | |
| 269 anc = anc->_idom; // Walk up till anc is as high as LCA | |
| 270 | |
| 271 while (LCA->_dom_depth > anc->_dom_depth) | |
| 272 LCA = LCA->_idom; // Walk up till LCA is as high as anc | |
| 273 | |
| 274 while (LCA != anc) { // Walk both up till they are the same | |
| 275 LCA = LCA->_idom; | |
| 276 anc = anc->_idom; | |
| 277 } | |
| 278 | |
| 279 return LCA; | |
| 280 } | |
| 281 | |
| 282 //--------------------------raise_LCA_above_use-------------------------------- | |
| 283 // We are placing a definition, and have been given a def->use edge. | |
| 284 // The definition must dominate the use, so move the LCA upward in the | |
| 285 // dominator tree to dominate the use. If the use is a phi, adjust | |
| 286 // the LCA only with the phi input paths which actually use this def. | |
| 287 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) { | |
| 288 Block* buse = bbs[use->_idx]; | |
| 289 if (buse == NULL) return LCA; // Unused killing Projs have no use block | |
| 290 if (!use->is_Phi()) return buse->dom_lca(LCA); | |
| 291 uint pmax = use->req(); // Number of Phi inputs | |
| 292 // Why does not this loop just break after finding the matching input to | |
| 293 // the Phi? Well...it's like this. I do not have true def-use/use-def | |
| 294 // chains. Means I cannot distinguish, from the def-use direction, which | |
| 295 // of many use-defs lead from the same use to the same def. That is, this | |
| 296 // Phi might have several uses of the same def. Each use appears in a | |
| 297 // different predecessor block. But when I enter here, I cannot distinguish | |
| 298 // which use-def edge I should find the predecessor block for. So I find | |
| 299 // them all. Means I do a little extra work if a Phi uses the same value | |
| 300 // more than once. | |
| 301 for (uint j=1; j<pmax; j++) { // For all inputs | |
| 302 if (use->in(j) == def) { // Found matching input? | |
| 303 Block* pred = bbs[buse->pred(j)->_idx]; | |
| 304 LCA = pred->dom_lca(LCA); | |
| 305 } | |
| 306 } | |
| 307 return LCA; | |
| 308 } | |
| 309 | |
| 310 //----------------------------raise_LCA_above_marks---------------------------- | |
| 311 // Return a new LCA that dominates LCA and any of its marked predecessors. | |
| 312 // Search all my parents up to 'early' (exclusive), looking for predecessors | |
| 313 // which are marked with the given index. Return the LCA (in the dom tree) | |
| 314 // of all marked blocks. If there are none marked, return the original | |
| 315 // LCA. | |
| 316 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, | |
| 317 Block* early, Block_Array &bbs) { | |
| 318 Block_List worklist; | |
| 319 worklist.push(LCA); | |
| 320 while (worklist.size() > 0) { | |
| 321 Block* mid = worklist.pop(); | |
| 322 if (mid == early) continue; // stop searching here | |
| 323 | |
| 324 // Test and set the visited bit. | |
| 325 if (mid->raise_LCA_visited() == mark) continue; // already visited | |
| 326 | |
| 327 // Don't process the current LCA, otherwise the search may terminate early | |
| 328 if (mid != LCA && mid->raise_LCA_mark() == mark) { | |
| 329 // Raise the LCA. | |
| 330 LCA = mid->dom_lca(LCA); | |
| 331 if (LCA == early) break; // stop searching everywhere | |
| 332 assert(early->dominates(LCA), "early is high enough"); | |
| 333 // Resume searching at that point, skipping intermediate levels. | |
| 334 worklist.push(LCA); | |
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335 if (LCA == mid) |
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336 continue; // Don't mark as visited to avoid early termination. |
| 0 | 337 } else { |
| 338 // Keep searching through this block's predecessors. | |
| 339 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { | |
| 340 Block* mid_parent = bbs[ mid->pred(j)->_idx ]; | |
| 341 worklist.push(mid_parent); | |
| 342 } | |
| 343 } | |
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344 mid->set_raise_LCA_visited(mark); |
| 0 | 345 } |
| 346 return LCA; | |
| 347 } | |
| 348 | |
| 349 //--------------------------memory_early_block-------------------------------- | |
| 350 // This is a variation of find_deepest_input, the heart of schedule_early. | |
| 351 // Find the "early" block for a load, if we considered only memory and | |
| 352 // address inputs, that is, if other data inputs were ignored. | |
| 353 // | |
| 354 // Because a subset of edges are considered, the resulting block will | |
| 355 // be earlier (at a shallower dom_depth) than the true schedule_early | |
| 356 // point of the node. We compute this earlier block as a more permissive | |
| 357 // site for anti-dependency insertion, but only if subsume_loads is enabled. | |
| 358 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) { | |
| 359 Node* base; | |
| 360 Node* index; | |
| 361 Node* store = load->in(MemNode::Memory); | |
| 362 load->as_Mach()->memory_inputs(base, index); | |
| 363 | |
| 364 assert(base != NodeSentinel && index != NodeSentinel, | |
| 365 "unexpected base/index inputs"); | |
| 366 | |
| 367 Node* mem_inputs[4]; | |
| 368 int mem_inputs_length = 0; | |
| 369 if (base != NULL) mem_inputs[mem_inputs_length++] = base; | |
| 370 if (index != NULL) mem_inputs[mem_inputs_length++] = index; | |
| 371 if (store != NULL) mem_inputs[mem_inputs_length++] = store; | |
| 372 | |
| 373 // In the comparision below, add one to account for the control input, | |
| 374 // which may be null, but always takes up a spot in the in array. | |
| 375 if (mem_inputs_length + 1 < (int) load->req()) { | |
| 376 // This "load" has more inputs than just the memory, base and index inputs. | |
| 377 // For purposes of checking anti-dependences, we need to start | |
| 378 // from the early block of only the address portion of the instruction, | |
| 379 // and ignore other blocks that may have factored into the wider | |
| 380 // schedule_early calculation. | |
| 381 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0); | |
| 382 | |
| 383 Block* deepb = NULL; // Deepest block so far | |
| 384 int deepb_dom_depth = 0; | |
| 385 for (int i = 0; i < mem_inputs_length; i++) { | |
| 386 Block* inb = bbs[mem_inputs[i]->_idx]; | |
| 387 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
| 388 // The new inb must be dominated by the previous deepb. | |
| 389 // The various inputs must be linearly ordered in the dom | |
| 390 // tree, or else there will not be a unique deepest block. | |
| 391 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs)); | |
| 392 deepb = inb; // Save deepest block | |
| 393 deepb_dom_depth = deepb->_dom_depth; | |
| 394 } | |
| 395 } | |
| 396 early = deepb; | |
| 397 } | |
| 398 | |
| 399 return early; | |
| 400 } | |
| 401 | |
| 402 //--------------------------insert_anti_dependences--------------------------- | |
| 403 // A load may need to witness memory that nearby stores can overwrite. | |
| 404 // For each nearby store, either insert an "anti-dependence" edge | |
| 405 // from the load to the store, or else move LCA upward to force the | |
| 406 // load to (eventually) be scheduled in a block above the store. | |
| 407 // | |
| 408 // Do not add edges to stores on distinct control-flow paths; | |
| 409 // only add edges to stores which might interfere. | |
| 410 // | |
| 411 // Return the (updated) LCA. There will not be any possibly interfering | |
| 412 // store between the load's "early block" and the updated LCA. | |
| 413 // Any stores in the updated LCA will have new precedence edges | |
| 414 // back to the load. The caller is expected to schedule the load | |
| 415 // in the LCA, in which case the precedence edges will make LCM | |
| 416 // preserve anti-dependences. The caller may also hoist the load | |
| 417 // above the LCA, if it is not the early block. | |
| 418 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) { | |
| 419 assert(load->needs_anti_dependence_check(), "must be a load of some sort"); | |
| 420 assert(LCA != NULL, ""); | |
| 421 DEBUG_ONLY(Block* LCA_orig = LCA); | |
| 422 | |
| 423 // Compute the alias index. Loads and stores with different alias indices | |
| 424 // do not need anti-dependence edges. | |
| 425 uint load_alias_idx = C->get_alias_index(load->adr_type()); | |
| 426 #ifdef ASSERT | |
| 427 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 && | |
| 428 (PrintOpto || VerifyAliases || | |
| 429 PrintMiscellaneous && (WizardMode || Verbose))) { | |
| 430 // Load nodes should not consume all of memory. | |
| 431 // Reporting a bottom type indicates a bug in adlc. | |
| 432 // If some particular type of node validly consumes all of memory, | |
| 433 // sharpen the preceding "if" to exclude it, so we can catch bugs here. | |
| 434 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory."); | |
| 435 load->dump(2); | |
| 436 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, ""); | |
| 437 } | |
| 438 #endif | |
| 439 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp), | |
| 440 "String compare is only known 'load' that does not conflict with any stores"); | |
| 441 | |
| 442 if (!C->alias_type(load_alias_idx)->is_rewritable()) { | |
| 443 // It is impossible to spoil this load by putting stores before it, | |
| 444 // because we know that the stores will never update the value | |
| 445 // which 'load' must witness. | |
| 446 return LCA; | |
| 447 } | |
| 448 | |
| 449 node_idx_t load_index = load->_idx; | |
| 450 | |
| 451 // Note the earliest legal placement of 'load', as determined by | |
| 452 // by the unique point in the dom tree where all memory effects | |
| 453 // and other inputs are first available. (Computed by schedule_early.) | |
| 454 // For normal loads, 'early' is the shallowest place (dom graph wise) | |
| 455 // to look for anti-deps between this load and any store. | |
| 456 Block* early = _bbs[load_index]; | |
| 457 | |
| 458 // If we are subsuming loads, compute an "early" block that only considers | |
| 459 // memory or address inputs. This block may be different than the | |
| 460 // schedule_early block in that it could be at an even shallower depth in the | |
| 461 // dominator tree, and allow for a broader discovery of anti-dependences. | |
| 462 if (C->subsume_loads()) { | |
| 463 early = memory_early_block(load, early, _bbs); | |
| 464 } | |
| 465 | |
| 466 ResourceArea *area = Thread::current()->resource_area(); | |
| 467 Node_List worklist_mem(area); // prior memory state to store | |
| 468 Node_List worklist_store(area); // possible-def to explore | |
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469 Node_List worklist_visited(area); // visited mergemem nodes |
| 0 | 470 Node_List non_early_stores(area); // all relevant stores outside of early |
| 471 bool must_raise_LCA = false; | |
| 472 | |
| 473 #ifdef TRACK_PHI_INPUTS | |
| 474 // %%% This extra checking fails because MergeMem nodes are not GVNed. | |
| 475 // Provide "phi_inputs" to check if every input to a PhiNode is from the | |
| 476 // original memory state. This indicates a PhiNode for which should not | |
| 477 // prevent the load from sinking. For such a block, set_raise_LCA_mark | |
| 478 // may be overly conservative. | |
| 479 // Mechanism: count inputs seen for each Phi encountered in worklist_store. | |
| 480 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0)); | |
| 481 #endif | |
| 482 | |
| 483 // 'load' uses some memory state; look for users of the same state. | |
| 484 // Recurse through MergeMem nodes to the stores that use them. | |
| 485 | |
| 486 // Each of these stores is a possible definition of memory | |
| 487 // that 'load' needs to use. We need to force 'load' | |
| 488 // to occur before each such store. When the store is in | |
| 489 // the same block as 'load', we insert an anti-dependence | |
| 490 // edge load->store. | |
| 491 | |
| 492 // The relevant stores "nearby" the load consist of a tree rooted | |
| 493 // at initial_mem, with internal nodes of type MergeMem. | |
| 494 // Therefore, the branches visited by the worklist are of this form: | |
| 495 // initial_mem -> (MergeMem ->)* store | |
| 496 // The anti-dependence constraints apply only to the fringe of this tree. | |
| 497 | |
| 498 Node* initial_mem = load->in(MemNode::Memory); | |
| 499 worklist_store.push(initial_mem); | |
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500 worklist_visited.push(initial_mem); |
| 0 | 501 worklist_mem.push(NULL); |
| 502 while (worklist_store.size() > 0) { | |
| 503 // Examine a nearby store to see if it might interfere with our load. | |
| 504 Node* mem = worklist_mem.pop(); | |
| 505 Node* store = worklist_store.pop(); | |
| 506 uint op = store->Opcode(); | |
| 507 | |
| 508 // MergeMems do not directly have anti-deps. | |
| 509 // Treat them as internal nodes in a forward tree of memory states, | |
| 510 // the leaves of which are each a 'possible-def'. | |
| 511 if (store == initial_mem // root (exclusive) of tree we are searching | |
| 512 || op == Op_MergeMem // internal node of tree we are searching | |
| 513 ) { | |
| 514 mem = store; // It's not a possibly interfering store. | |
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515 if (store == initial_mem) |
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516 initial_mem = NULL; // only process initial memory once |
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517 |
| 0 | 518 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { |
| 519 store = mem->fast_out(i); | |
| 520 if (store->is_MergeMem()) { | |
| 521 // Be sure we don't get into combinatorial problems. | |
| 522 // (Allow phis to be repeated; they can merge two relevant states.) | |
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523 uint j = worklist_visited.size(); |
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524 for (; j > 0; j--) { |
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525 if (worklist_visited.at(j-1) == store) break; |
| 0 | 526 } |
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527 if (j > 0) continue; // already on work list; do not repeat |
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528 worklist_visited.push(store); |
| 0 | 529 } |
| 530 worklist_mem.push(mem); | |
| 531 worklist_store.push(store); | |
| 532 } | |
| 533 continue; | |
| 534 } | |
| 535 | |
| 536 if (op == Op_MachProj || op == Op_Catch) continue; | |
| 537 if (store->needs_anti_dependence_check()) continue; // not really a store | |
| 538 | |
| 539 // Compute the alias index. Loads and stores with different alias | |
| 540 // indices do not need anti-dependence edges. Wide MemBar's are | |
| 541 // anti-dependent on everything (except immutable memories). | |
| 542 const TypePtr* adr_type = store->adr_type(); | |
| 543 if (!C->can_alias(adr_type, load_alias_idx)) continue; | |
| 544 | |
| 545 // Most slow-path runtime calls do NOT modify Java memory, but | |
| 546 // they can block and so write Raw memory. | |
| 547 if (store->is_Mach()) { | |
| 548 MachNode* mstore = store->as_Mach(); | |
| 549 if (load_alias_idx != Compile::AliasIdxRaw) { | |
| 550 // Check for call into the runtime using the Java calling | |
| 551 // convention (and from there into a wrapper); it has no | |
| 552 // _method. Can't do this optimization for Native calls because | |
| 553 // they CAN write to Java memory. | |
| 554 if (mstore->ideal_Opcode() == Op_CallStaticJava) { | |
| 555 assert(mstore->is_MachSafePoint(), ""); | |
| 556 MachSafePointNode* ms = (MachSafePointNode*) mstore; | |
| 557 assert(ms->is_MachCallJava(), ""); | |
| 558 MachCallJavaNode* mcj = (MachCallJavaNode*) ms; | |
| 559 if (mcj->_method == NULL) { | |
| 560 // These runtime calls do not write to Java visible memory | |
| 561 // (other than Raw) and so do not require anti-dependence edges. | |
| 562 continue; | |
| 563 } | |
| 564 } | |
| 565 // Same for SafePoints: they read/write Raw but only read otherwise. | |
| 566 // This is basically a workaround for SafePoints only defining control | |
| 567 // instead of control + memory. | |
| 568 if (mstore->ideal_Opcode() == Op_SafePoint) | |
| 569 continue; | |
| 570 } else { | |
| 571 // Some raw memory, such as the load of "top" at an allocation, | |
| 572 // can be control dependent on the previous safepoint. See | |
| 573 // comments in GraphKit::allocate_heap() about control input. | |
| 574 // Inserting an anti-dep between such a safepoint and a use | |
| 575 // creates a cycle, and will cause a subsequent failure in | |
| 576 // local scheduling. (BugId 4919904) | |
| 577 // (%%% How can a control input be a safepoint and not a projection??) | |
| 578 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore) | |
| 579 continue; | |
| 580 } | |
| 581 } | |
| 582 | |
| 583 // Identify a block that the current load must be above, | |
| 584 // or else observe that 'store' is all the way up in the | |
| 585 // earliest legal block for 'load'. In the latter case, | |
| 586 // immediately insert an anti-dependence edge. | |
| 587 Block* store_block = _bbs[store->_idx]; | |
| 588 assert(store_block != NULL, "unused killing projections skipped above"); | |
| 589 | |
| 590 if (store->is_Phi()) { | |
| 591 // 'load' uses memory which is one (or more) of the Phi's inputs. | |
| 592 // It must be scheduled not before the Phi, but rather before | |
| 593 // each of the relevant Phi inputs. | |
| 594 // | |
| 595 // Instead of finding the LCA of all inputs to a Phi that match 'mem', | |
| 596 // we mark each corresponding predecessor block and do a combined | |
| 597 // hoisting operation later (raise_LCA_above_marks). | |
| 598 // | |
| 599 // Do not assert(store_block != early, "Phi merging memory after access") | |
| 600 // PhiNode may be at start of block 'early' with backedge to 'early' | |
| 601 DEBUG_ONLY(bool found_match = false); | |
| 602 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) { | |
| 603 if (store->in(j) == mem) { // Found matching input? | |
| 604 DEBUG_ONLY(found_match = true); | |
| 605 Block* pred_block = _bbs[store_block->pred(j)->_idx]; | |
| 606 if (pred_block != early) { | |
| 607 // If any predecessor of the Phi matches the load's "early block", | |
| 608 // we do not need a precedence edge between the Phi and 'load' | |
| 605 | 609 // since the load will be forced into a block preceding the Phi. |
| 0 | 610 pred_block->set_raise_LCA_mark(load_index); |
| 611 assert(!LCA_orig->dominates(pred_block) || | |
| 612 early->dominates(pred_block), "early is high enough"); | |
| 613 must_raise_LCA = true; | |
| 614 } | |
| 615 } | |
| 616 } | |
| 617 assert(found_match, "no worklist bug"); | |
| 618 #ifdef TRACK_PHI_INPUTS | |
| 619 #ifdef ASSERT | |
| 620 // This assert asks about correct handling of PhiNodes, which may not | |
| 621 // have all input edges directly from 'mem'. See BugId 4621264 | |
| 622 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1; | |
| 623 // Increment by exactly one even if there are multiple copies of 'mem' | |
| 624 // coming into the phi, because we will run this block several times | |
| 625 // if there are several copies of 'mem'. (That's how DU iterators work.) | |
| 626 phi_inputs.at_put(store->_idx, num_mem_inputs); | |
| 627 assert(PhiNode::Input + num_mem_inputs < store->req(), | |
| 628 "Expect at least one phi input will not be from original memory state"); | |
| 629 #endif //ASSERT | |
| 630 #endif //TRACK_PHI_INPUTS | |
| 631 } else if (store_block != early) { | |
| 632 // 'store' is between the current LCA and earliest possible block. | |
| 633 // Label its block, and decide later on how to raise the LCA | |
| 634 // to include the effect on LCA of this store. | |
| 635 // If this store's block gets chosen as the raised LCA, we | |
| 636 // will find him on the non_early_stores list and stick him | |
| 637 // with a precedence edge. | |
| 638 // (But, don't bother if LCA is already raised all the way.) | |
| 639 if (LCA != early) { | |
| 640 store_block->set_raise_LCA_mark(load_index); | |
| 641 must_raise_LCA = true; | |
| 642 non_early_stores.push(store); | |
| 643 } | |
| 644 } else { | |
| 645 // Found a possibly-interfering store in the load's 'early' block. | |
| 646 // This means 'load' cannot sink at all in the dominator tree. | |
| 647 // Add an anti-dep edge, and squeeze 'load' into the highest block. | |
| 648 assert(store != load->in(0), "dependence cycle found"); | |
| 649 if (verify) { | |
| 650 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
| 651 } else { | |
| 652 store->add_prec(load); | |
| 653 } | |
| 654 LCA = early; | |
| 655 // This turns off the process of gathering non_early_stores. | |
| 656 } | |
| 657 } | |
| 658 // (Worklist is now empty; all nearby stores have been visited.) | |
| 659 | |
| 660 // Finished if 'load' must be scheduled in its 'early' block. | |
| 661 // If we found any stores there, they have already been given | |
| 662 // precedence edges. | |
| 663 if (LCA == early) return LCA; | |
| 664 | |
| 665 // We get here only if there are no possibly-interfering stores | |
| 666 // in the load's 'early' block. Move LCA up above all predecessors | |
| 667 // which contain stores we have noted. | |
| 668 // | |
| 669 // The raised LCA block can be a home to such interfering stores, | |
| 670 // but its predecessors must not contain any such stores. | |
| 671 // | |
| 672 // The raised LCA will be a lower bound for placing the load, | |
| 673 // preventing the load from sinking past any block containing | |
| 674 // a store that may invalidate the memory state required by 'load'. | |
| 675 if (must_raise_LCA) | |
| 676 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs); | |
| 677 if (LCA == early) return LCA; | |
| 678 | |
| 679 // Insert anti-dependence edges from 'load' to each store | |
| 680 // in the non-early LCA block. | |
| 681 // Mine the non_early_stores list for such stores. | |
| 682 if (LCA->raise_LCA_mark() == load_index) { | |
| 683 while (non_early_stores.size() > 0) { | |
| 684 Node* store = non_early_stores.pop(); | |
| 685 Block* store_block = _bbs[store->_idx]; | |
| 686 if (store_block == LCA) { | |
| 687 // add anti_dependence from store to load in its own block | |
| 688 assert(store != load->in(0), "dependence cycle found"); | |
| 689 if (verify) { | |
| 690 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
| 691 } else { | |
| 692 store->add_prec(load); | |
| 693 } | |
| 694 } else { | |
| 695 assert(store_block->raise_LCA_mark() == load_index, "block was marked"); | |
| 696 // Any other stores we found must be either inside the new LCA | |
| 697 // or else outside the original LCA. In the latter case, they | |
| 698 // did not interfere with any use of 'load'. | |
| 699 assert(LCA->dominates(store_block) | |
| 700 || !LCA_orig->dominates(store_block), "no stray stores"); | |
| 701 } | |
| 702 } | |
| 703 } | |
| 704 | |
| 705 // Return the highest block containing stores; any stores | |
| 706 // within that block have been given anti-dependence edges. | |
| 707 return LCA; | |
| 708 } | |
| 709 | |
| 710 // This class is used to iterate backwards over the nodes in the graph. | |
| 711 | |
| 712 class Node_Backward_Iterator { | |
| 713 | |
| 714 private: | |
| 715 Node_Backward_Iterator(); | |
| 716 | |
| 717 public: | |
| 718 // Constructor for the iterator | |
| 719 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs); | |
| 720 | |
| 721 // Postincrement operator to iterate over the nodes | |
| 722 Node *next(); | |
| 723 | |
| 724 private: | |
| 725 VectorSet &_visited; | |
| 726 Node_List &_stack; | |
| 727 Block_Array &_bbs; | |
| 728 }; | |
| 729 | |
| 730 // Constructor for the Node_Backward_Iterator | |
| 731 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs ) | |
| 732 : _visited(visited), _stack(stack), _bbs(bbs) { | |
| 733 // The stack should contain exactly the root | |
| 734 stack.clear(); | |
| 735 stack.push(root); | |
| 736 | |
| 737 // Clear the visited bits | |
| 738 visited.Clear(); | |
| 739 } | |
| 740 | |
| 741 // Iterator for the Node_Backward_Iterator | |
| 742 Node *Node_Backward_Iterator::next() { | |
| 743 | |
| 744 // If the _stack is empty, then just return NULL: finished. | |
| 745 if ( !_stack.size() ) | |
| 746 return NULL; | |
| 747 | |
| 748 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been | |
| 749 // made stateless, so I do not need to record the index 'i' on my _stack. | |
| 750 // Instead I visit all users each time, scanning for unvisited users. | |
| 751 // I visit unvisited not-anti-dependence users first, then anti-dependent | |
| 752 // children next. | |
| 753 Node *self = _stack.pop(); | |
| 754 | |
| 755 // I cycle here when I am entering a deeper level of recursion. | |
| 756 // The key variable 'self' was set prior to jumping here. | |
| 757 while( 1 ) { | |
| 758 | |
| 759 _visited.set(self->_idx); | |
| 760 | |
| 761 // Now schedule all uses as late as possible. | |
| 762 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx; | |
| 763 uint src_rpo = _bbs[src]->_rpo; | |
| 764 | |
| 765 // Schedule all nodes in a post-order visit | |
| 766 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any | |
| 767 | |
| 768 // Scan for unvisited nodes | |
| 769 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
| 770 // For all uses, schedule late | |
| 771 Node* n = self->fast_out(i); // Use | |
| 772 | |
| 773 // Skip already visited children | |
| 774 if ( _visited.test(n->_idx) ) | |
| 775 continue; | |
| 776 | |
| 777 // do not traverse backward control edges | |
| 778 Node *use = n->is_Proj() ? n->in(0) : n; | |
| 779 uint use_rpo = _bbs[use->_idx]->_rpo; | |
| 780 | |
| 781 if ( use_rpo < src_rpo ) | |
| 782 continue; | |
| 783 | |
| 784 // Phi nodes always precede uses in a basic block | |
| 785 if ( use_rpo == src_rpo && use->is_Phi() ) | |
| 786 continue; | |
| 787 | |
| 788 unvisited = n; // Found unvisited | |
| 789 | |
| 790 // Check for possible-anti-dependent | |
| 791 if( !n->needs_anti_dependence_check() ) | |
| 792 break; // Not visited, not anti-dep; schedule it NOW | |
| 793 } | |
| 794 | |
| 795 // Did I find an unvisited not-anti-dependent Node? | |
| 796 if ( !unvisited ) | |
| 797 break; // All done with children; post-visit 'self' | |
| 798 | |
| 799 // Visit the unvisited Node. Contains the obvious push to | |
| 800 // indicate I'm entering a deeper level of recursion. I push the | |
| 801 // old state onto the _stack and set a new state and loop (recurse). | |
| 802 _stack.push(self); | |
| 803 self = unvisited; | |
| 804 } // End recursion loop | |
| 805 | |
| 806 return self; | |
| 807 } | |
| 808 | |
| 809 //------------------------------ComputeLatenciesBackwards---------------------- | |
| 810 // Compute the latency of all the instructions. | |
| 811 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) { | |
| 812 #ifndef PRODUCT | |
| 813 if (trace_opto_pipelining()) | |
| 814 tty->print("\n#---- ComputeLatenciesBackwards ----\n"); | |
| 815 #endif | |
| 816 | |
| 817 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
| 818 Node *n; | |
| 819 | |
| 820 // Walk over all the nodes from last to first | |
| 821 while (n = iter.next()) { | |
| 822 // Set the latency for the definitions of this instruction | |
| 823 partial_latency_of_defs(n); | |
| 824 } | |
| 825 } // end ComputeLatenciesBackwards | |
| 826 | |
| 827 //------------------------------partial_latency_of_defs------------------------ | |
| 828 // Compute the latency impact of this node on all defs. This computes | |
| 829 // a number that increases as we approach the beginning of the routine. | |
| 830 void PhaseCFG::partial_latency_of_defs(Node *n) { | |
| 831 // Set the latency for this instruction | |
| 832 #ifndef PRODUCT | |
| 833 if (trace_opto_pipelining()) { | |
| 834 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", | |
| 835 n->_idx, _node_latency.at_grow(n->_idx)); | |
| 836 dump(); | |
| 837 } | |
| 838 #endif | |
| 839 | |
| 840 if (n->is_Proj()) | |
| 841 n = n->in(0); | |
| 842 | |
| 843 if (n->is_Root()) | |
| 844 return; | |
| 845 | |
| 846 uint nlen = n->len(); | |
| 847 uint use_latency = _node_latency.at_grow(n->_idx); | |
| 848 uint use_pre_order = _bbs[n->_idx]->_pre_order; | |
| 849 | |
| 850 for ( uint j=0; j<nlen; j++ ) { | |
| 851 Node *def = n->in(j); | |
| 852 | |
| 853 if (!def || def == n) | |
| 854 continue; | |
| 855 | |
| 856 // Walk backwards thru projections | |
| 857 if (def->is_Proj()) | |
| 858 def = def->in(0); | |
| 859 | |
| 860 #ifndef PRODUCT | |
| 861 if (trace_opto_pipelining()) { | |
| 862 tty->print("# in(%2d): ", j); | |
| 863 def->dump(); | |
| 864 } | |
| 865 #endif | |
| 866 | |
| 867 // If the defining block is not known, assume it is ok | |
| 868 Block *def_block = _bbs[def->_idx]; | |
| 869 uint def_pre_order = def_block ? def_block->_pre_order : 0; | |
| 870 | |
| 871 if ( (use_pre_order < def_pre_order) || | |
| 872 (use_pre_order == def_pre_order && n->is_Phi()) ) | |
| 873 continue; | |
| 874 | |
| 875 uint delta_latency = n->latency(j); | |
| 876 uint current_latency = delta_latency + use_latency; | |
| 877 | |
| 878 if (_node_latency.at_grow(def->_idx) < current_latency) { | |
| 879 _node_latency.at_put_grow(def->_idx, current_latency); | |
| 880 } | |
| 881 | |
| 882 #ifndef PRODUCT | |
| 883 if (trace_opto_pipelining()) { | |
| 884 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", | |
| 885 use_latency, j, delta_latency, current_latency, def->_idx, | |
| 886 _node_latency.at_grow(def->_idx)); | |
| 887 } | |
| 888 #endif | |
| 889 } | |
| 890 } | |
| 891 | |
| 892 //------------------------------latency_from_use------------------------------- | |
| 893 // Compute the latency of a specific use | |
| 894 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) { | |
| 895 // If self-reference, return no latency | |
| 896 if (use == n || use->is_Root()) | |
| 897 return 0; | |
| 898 | |
| 899 uint def_pre_order = _bbs[def->_idx]->_pre_order; | |
| 900 uint latency = 0; | |
| 901 | |
| 902 // If the use is not a projection, then it is simple... | |
| 903 if (!use->is_Proj()) { | |
| 904 #ifndef PRODUCT | |
| 905 if (trace_opto_pipelining()) { | |
| 906 tty->print("# out(): "); | |
| 907 use->dump(); | |
| 908 } | |
| 909 #endif | |
| 910 | |
| 911 uint use_pre_order = _bbs[use->_idx]->_pre_order; | |
| 912 | |
| 913 if (use_pre_order < def_pre_order) | |
| 914 return 0; | |
| 915 | |
| 916 if (use_pre_order == def_pre_order && use->is_Phi()) | |
| 917 return 0; | |
| 918 | |
| 919 uint nlen = use->len(); | |
| 920 uint nl = _node_latency.at_grow(use->_idx); | |
| 921 | |
| 922 for ( uint j=0; j<nlen; j++ ) { | |
| 923 if (use->in(j) == n) { | |
| 924 // Change this if we want local latencies | |
| 925 uint ul = use->latency(j); | |
| 926 uint l = ul + nl; | |
| 927 if (latency < l) latency = l; | |
| 928 #ifndef PRODUCT | |
| 929 if (trace_opto_pipelining()) { | |
| 930 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d", | |
| 931 nl, j, ul, l, latency); | |
| 932 } | |
| 933 #endif | |
| 934 } | |
| 935 } | |
| 936 } else { | |
| 937 // This is a projection, just grab the latency of the use(s) | |
| 938 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) { | |
| 939 uint l = latency_from_use(use, def, use->fast_out(j)); | |
| 940 if (latency < l) latency = l; | |
| 941 } | |
| 942 } | |
| 943 | |
| 944 return latency; | |
| 945 } | |
| 946 | |
| 947 //------------------------------latency_from_uses------------------------------ | |
| 948 // Compute the latency of this instruction relative to all of it's uses. | |
| 949 // This computes a number that increases as we approach the beginning of the | |
| 950 // routine. | |
| 951 void PhaseCFG::latency_from_uses(Node *n) { | |
| 952 // Set the latency for this instruction | |
| 953 #ifndef PRODUCT | |
| 954 if (trace_opto_pipelining()) { | |
| 955 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", | |
| 956 n->_idx, _node_latency.at_grow(n->_idx)); | |
| 957 dump(); | |
| 958 } | |
| 959 #endif | |
| 960 uint latency=0; | |
| 961 const Node *def = n->is_Proj() ? n->in(0): n; | |
| 962 | |
| 963 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
| 964 uint l = latency_from_use(n, def, n->fast_out(i)); | |
| 965 | |
| 966 if (latency < l) latency = l; | |
| 967 } | |
| 968 | |
| 969 _node_latency.at_put_grow(n->_idx, latency); | |
| 970 } | |
| 971 | |
| 972 //------------------------------hoist_to_cheaper_block------------------------- | |
| 973 // Pick a block for node self, between early and LCA, that is a cheaper | |
| 974 // alternative to LCA. | |
| 975 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) { | |
| 976 const double delta = 1+PROB_UNLIKELY_MAG(4); | |
| 977 Block* least = LCA; | |
| 978 double least_freq = least->_freq; | |
| 979 uint target = _node_latency.at_grow(self->_idx); | |
| 980 uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
| 981 uint end_latency = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx); | |
| 982 bool in_latency = (target <= start_latency); | |
| 983 const Block* root_block = _bbs[_root->_idx]; | |
| 984 | |
| 985 // Turn off latency scheduling if scheduling is just plain off | |
| 986 if (!C->do_scheduling()) | |
| 987 in_latency = true; | |
| 988 | |
| 989 // Do not hoist (to cover latency) instructions which target a | |
| 990 // single register. Hoisting stretches the live range of the | |
| 991 // single register and may force spilling. | |
| 992 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
| 993 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty()) | |
| 994 in_latency = true; | |
| 995 | |
| 996 #ifndef PRODUCT | |
| 997 if (trace_opto_pipelining()) { | |
| 998 tty->print("# Find cheaper block for latency %d: ", | |
| 999 _node_latency.at_grow(self->_idx)); | |
| 1000 self->dump(); | |
| 1001 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
| 1002 LCA->_pre_order, | |
| 1003 LCA->_nodes[0]->_idx, | |
| 1004 start_latency, | |
| 1005 LCA->_nodes[LCA->end_idx()]->_idx, | |
| 1006 end_latency, | |
| 1007 least_freq); | |
| 1008 } | |
| 1009 #endif | |
| 1010 | |
| 1011 // Walk up the dominator tree from LCA (Lowest common ancestor) to | |
| 1012 // the earliest legal location. Capture the least execution frequency. | |
| 1013 while (LCA != early) { | |
| 1014 LCA = LCA->_idom; // Follow up the dominator tree | |
| 1015 | |
| 1016 if (LCA == NULL) { | |
| 1017 // Bailout without retry | |
| 1018 C->record_method_not_compilable("late schedule failed: LCA == NULL"); | |
| 1019 return least; | |
| 1020 } | |
| 1021 | |
| 1022 // Don't hoist machine instructions to the root basic block | |
| 1023 if (mach && LCA == root_block) | |
| 1024 break; | |
| 1025 | |
| 1026 uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
| 1027 uint end_idx = LCA->end_idx(); | |
| 1028 uint end_lat = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx); | |
| 1029 double LCA_freq = LCA->_freq; | |
| 1030 #ifndef PRODUCT | |
| 1031 if (trace_opto_pipelining()) { | |
| 1032 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
| 1033 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq); | |
| 1034 } | |
| 1035 #endif | |
| 1036 if (LCA_freq < least_freq || // Better Frequency | |
| 1037 ( !in_latency && // No block containing latency | |
| 1038 LCA_freq < least_freq * delta && // No worse frequency | |
| 1039 target >= end_lat && // within latency range | |
| 1040 !self->is_iteratively_computed() ) // But don't hoist IV increments | |
| 1041 // because they may end up above other uses of their phi forcing | |
| 1042 // their result register to be different from their input. | |
| 1043 ) { | |
| 1044 least = LCA; // Found cheaper block | |
| 1045 least_freq = LCA_freq; | |
| 1046 start_latency = start_lat; | |
| 1047 end_latency = end_lat; | |
| 1048 if (target <= start_lat) | |
| 1049 in_latency = true; | |
| 1050 } | |
| 1051 } | |
| 1052 | |
| 1053 #ifndef PRODUCT | |
| 1054 if (trace_opto_pipelining()) { | |
| 1055 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g", | |
| 1056 least->_pre_order, start_latency, least_freq); | |
| 1057 } | |
| 1058 #endif | |
| 1059 | |
| 1060 // See if the latency needs to be updated | |
| 1061 if (target < end_latency) { | |
| 1062 #ifndef PRODUCT | |
| 1063 if (trace_opto_pipelining()) { | |
| 1064 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency); | |
| 1065 } | |
| 1066 #endif | |
| 1067 _node_latency.at_put_grow(self->_idx, end_latency); | |
| 1068 partial_latency_of_defs(self); | |
| 1069 } | |
| 1070 | |
| 1071 return least; | |
| 1072 } | |
| 1073 | |
| 1074 | |
| 1075 //------------------------------schedule_late----------------------------------- | |
| 1076 // Now schedule all codes as LATE as possible. This is the LCA in the | |
| 1077 // dominator tree of all USES of a value. Pick the block with the least | |
| 1078 // loop nesting depth that is lowest in the dominator tree. | |
| 1079 extern const char must_clone[]; | |
| 1080 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) { | |
| 1081 #ifndef PRODUCT | |
| 1082 if (trace_opto_pipelining()) | |
| 1083 tty->print("\n#---- schedule_late ----\n"); | |
| 1084 #endif | |
| 1085 | |
| 1086 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
| 1087 Node *self; | |
| 1088 | |
| 1089 // Walk over all the nodes from last to first | |
| 1090 while (self = iter.next()) { | |
| 1091 Block* early = _bbs[self->_idx]; // Earliest legal placement | |
| 1092 | |
| 1093 if (self->is_top()) { | |
| 1094 // Top node goes in bb #2 with other constants. | |
| 1095 // It must be special-cased, because it has no out edges. | |
| 1096 early->add_inst(self); | |
| 1097 continue; | |
| 1098 } | |
| 1099 | |
| 1100 // No uses, just terminate | |
| 1101 if (self->outcnt() == 0) { | |
| 1102 assert(self->Opcode() == Op_MachProj, "sanity"); | |
| 1103 continue; // Must be a dead machine projection | |
| 1104 } | |
| 1105 | |
| 1106 // If node is pinned in the block, then no scheduling can be done. | |
| 1107 if( self->pinned() ) // Pinned in block? | |
| 1108 continue; | |
| 1109 | |
| 1110 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
| 1111 if (mach) { | |
| 1112 switch (mach->ideal_Opcode()) { | |
| 1113 case Op_CreateEx: | |
| 1114 // Don't move exception creation | |
| 1115 early->add_inst(self); | |
| 1116 continue; | |
| 1117 break; | |
| 1118 case Op_CheckCastPP: | |
| 1119 // Don't move CheckCastPP nodes away from their input, if the input | |
| 1120 // is a rawptr (5071820). | |
| 1121 Node *def = self->in(1); | |
| 1122 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) { | |
| 1123 early->add_inst(self); | |
| 1124 continue; | |
| 1125 } | |
| 1126 break; | |
| 1127 } | |
| 1128 } | |
| 1129 | |
| 1130 // Gather LCA of all uses | |
| 1131 Block *LCA = NULL; | |
| 1132 { | |
| 1133 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
| 1134 // For all uses, find LCA | |
| 1135 Node* use = self->fast_out(i); | |
| 1136 LCA = raise_LCA_above_use(LCA, use, self, _bbs); | |
| 1137 } | |
| 1138 } // (Hide defs of imax, i from rest of block.) | |
| 1139 | |
| 1140 // Place temps in the block of their use. This isn't a | |
| 1141 // requirement for correctness but it reduces useless | |
| 1142 // interference between temps and other nodes. | |
| 1143 if (mach != NULL && mach->is_MachTemp()) { | |
| 1144 _bbs.map(self->_idx, LCA); | |
| 1145 LCA->add_inst(self); | |
| 1146 continue; | |
| 1147 } | |
| 1148 | |
| 1149 // Check if 'self' could be anti-dependent on memory | |
| 1150 if (self->needs_anti_dependence_check()) { | |
| 1151 // Hoist LCA above possible-defs and insert anti-dependences to | |
| 1152 // defs in new LCA block. | |
| 1153 LCA = insert_anti_dependences(LCA, self); | |
| 1154 } | |
| 1155 | |
| 1156 if (early->_dom_depth > LCA->_dom_depth) { | |
| 1157 // Somehow the LCA has moved above the earliest legal point. | |
| 1158 // (One way this can happen is via memory_early_block.) | |
| 1159 if (C->subsume_loads() == true && !C->failing()) { | |
| 1160 // Retry with subsume_loads == false | |
| 1161 // If this is the first failure, the sentinel string will "stick" | |
| 1162 // to the Compile object, and the C2Compiler will see it and retry. | |
| 1163 C->record_failure(C2Compiler::retry_no_subsuming_loads()); | |
| 1164 } else { | |
| 1165 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth) | |
| 1166 C->record_method_not_compilable("late schedule failed: incorrect graph"); | |
| 1167 } | |
| 1168 return; | |
| 1169 } | |
| 1170 | |
| 1171 // If there is no opportunity to hoist, then we're done. | |
| 1172 bool try_to_hoist = (LCA != early); | |
| 1173 | |
| 1174 // Must clone guys stay next to use; no hoisting allowed. | |
| 1175 // Also cannot hoist guys that alter memory or are otherwise not | |
| 1176 // allocatable (hoisting can make a value live longer, leading to | |
| 1177 // anti and output dependency problems which are normally resolved | |
| 1178 // by the register allocator giving everyone a different register). | |
| 1179 if (mach != NULL && must_clone[mach->ideal_Opcode()]) | |
| 1180 try_to_hoist = false; | |
| 1181 | |
| 1182 Block* late = NULL; | |
| 1183 if (try_to_hoist) { | |
| 1184 // Now find the block with the least execution frequency. | |
| 1185 // Start at the latest schedule and work up to the earliest schedule | |
| 1186 // in the dominator tree. Thus the Node will dominate all its uses. | |
| 1187 late = hoist_to_cheaper_block(LCA, early, self); | |
| 1188 } else { | |
| 1189 // Just use the LCA of the uses. | |
| 1190 late = LCA; | |
| 1191 } | |
| 1192 | |
| 1193 // Put the node into target block | |
| 1194 schedule_node_into_block(self, late); | |
| 1195 | |
| 1196 #ifdef ASSERT | |
| 1197 if (self->needs_anti_dependence_check()) { | |
| 1198 // since precedence edges are only inserted when we're sure they | |
| 1199 // are needed make sure that after placement in a block we don't | |
| 1200 // need any new precedence edges. | |
| 1201 verify_anti_dependences(late, self); | |
| 1202 } | |
| 1203 #endif | |
| 1204 } // Loop until all nodes have been visited | |
| 1205 | |
| 1206 } // end ScheduleLate | |
| 1207 | |
| 1208 //------------------------------GlobalCodeMotion------------------------------- | |
| 1209 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) { | |
| 1210 ResourceMark rm; | |
| 1211 | |
| 1212 #ifndef PRODUCT | |
| 1213 if (trace_opto_pipelining()) { | |
| 1214 tty->print("\n---- Start GlobalCodeMotion ----\n"); | |
| 1215 } | |
| 1216 #endif | |
| 1217 | |
| 1218 // Initialize the bbs.map for things on the proj_list | |
| 1219 uint i; | |
| 1220 for( i=0; i < proj_list.size(); i++ ) | |
| 1221 _bbs.map(proj_list[i]->_idx, NULL); | |
| 1222 | |
| 1223 // Set the basic block for Nodes pinned into blocks | |
| 1224 Arena *a = Thread::current()->resource_area(); | |
| 1225 VectorSet visited(a); | |
| 1226 schedule_pinned_nodes( visited ); | |
| 1227 | |
| 1228 // Find the earliest Block any instruction can be placed in. Some | |
| 1229 // instructions are pinned into Blocks. Unpinned instructions can | |
| 1230 // appear in last block in which all their inputs occur. | |
| 1231 visited.Clear(); | |
| 1232 Node_List stack(a); | |
| 1233 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list | |
| 1234 if (!schedule_early(visited, stack)) { | |
| 1235 // Bailout without retry | |
| 1236 C->record_method_not_compilable("early schedule failed"); | |
| 1237 return; | |
| 1238 } | |
| 1239 | |
| 1240 // Build Def-Use edges. | |
| 1241 proj_list.push(_root); // Add real root as another root | |
| 1242 proj_list.pop(); | |
| 1243 | |
| 1244 // Compute the latency information (via backwards walk) for all the | |
| 1245 // instructions in the graph | |
| 1246 GrowableArray<uint> node_latency; | |
| 1247 _node_latency = node_latency; | |
| 1248 | |
| 1249 if( C->do_scheduling() ) | |
| 1250 ComputeLatenciesBackwards(visited, stack); | |
| 1251 | |
| 1252 // Now schedule all codes as LATE as possible. This is the LCA in the | |
| 1253 // dominator tree of all USES of a value. Pick the block with the least | |
| 1254 // loop nesting depth that is lowest in the dominator tree. | |
| 1255 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() ) | |
| 1256 schedule_late(visited, stack); | |
| 1257 if( C->failing() ) { | |
| 1258 // schedule_late fails only when graph is incorrect. | |
| 1259 assert(!VerifyGraphEdges, "verification should have failed"); | |
| 1260 return; | |
| 1261 } | |
| 1262 | |
| 1263 unique = C->unique(); | |
| 1264 | |
| 1265 #ifndef PRODUCT | |
| 1266 if (trace_opto_pipelining()) { | |
| 1267 tty->print("\n---- Detect implicit null checks ----\n"); | |
| 1268 } | |
| 1269 #endif | |
| 1270 | |
| 1271 // Detect implicit-null-check opportunities. Basically, find NULL checks | |
| 1272 // with suitable memory ops nearby. Use the memory op to do the NULL check. | |
| 1273 // I can generate a memory op if there is not one nearby. | |
| 1274 if (C->is_method_compilation()) { | |
| 1275 // Don't do it for natives, adapters, or runtime stubs | |
| 1276 int allowed_reasons = 0; | |
| 1277 // ...and don't do it when there have been too many traps, globally. | |
| 1278 for (int reason = (int)Deoptimization::Reason_none+1; | |
| 1279 reason < Compile::trapHistLength; reason++) { | |
| 1280 assert(reason < BitsPerInt, "recode bit map"); | |
| 1281 if (!C->too_many_traps((Deoptimization::DeoptReason) reason)) | |
| 1282 allowed_reasons |= nth_bit(reason); | |
| 1283 } | |
| 1284 // By reversing the loop direction we get a very minor gain on mpegaudio. | |
| 1285 // Feel free to revert to a forward loop for clarity. | |
| 1286 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) { | |
| 1287 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) { | |
| 1288 Node *proj = matcher._null_check_tests[i ]; | |
| 1289 Node *val = matcher._null_check_tests[i+1]; | |
| 1290 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons); | |
| 1291 // The implicit_null_check will only perform the transformation | |
| 1292 // if the null branch is truly uncommon, *and* it leads to an | |
| 1293 // uncommon trap. Combined with the too_many_traps guards | |
| 1294 // above, this prevents SEGV storms reported in 6366351, | |
| 1295 // by recompiling offending methods without this optimization. | |
| 1296 } | |
| 1297 } | |
| 1298 | |
| 1299 #ifndef PRODUCT | |
| 1300 if (trace_opto_pipelining()) { | |
| 1301 tty->print("\n---- Start Local Scheduling ----\n"); | |
| 1302 } | |
| 1303 #endif | |
| 1304 | |
| 1305 // Schedule locally. Right now a simple topological sort. | |
| 1306 // Later, do a real latency aware scheduler. | |
| 1307 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique()); | |
| 1308 memset( ready_cnt, -1, C->unique() * sizeof(int) ); | |
| 1309 visited.Clear(); | |
| 1310 for (i = 0; i < _num_blocks; i++) { | |
| 1311 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) { | |
| 1312 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { | |
| 1313 C->record_method_not_compilable("local schedule failed"); | |
| 1314 } | |
| 1315 return; | |
| 1316 } | |
| 1317 } | |
| 1318 | |
| 1319 // If we inserted any instructions between a Call and his CatchNode, | |
| 1320 // clone the instructions on all paths below the Catch. | |
| 1321 for( i=0; i < _num_blocks; i++ ) | |
| 1322 _blocks[i]->call_catch_cleanup(_bbs); | |
| 1323 | |
| 1324 #ifndef PRODUCT | |
| 1325 if (trace_opto_pipelining()) { | |
| 1326 tty->print("\n---- After GlobalCodeMotion ----\n"); | |
| 1327 for (uint i = 0; i < _num_blocks; i++) { | |
| 1328 _blocks[i]->dump(); | |
| 1329 } | |
| 1330 } | |
| 1331 #endif | |
| 1332 } | |
| 1333 | |
| 1334 | |
| 1335 //------------------------------Estimate_Block_Frequency----------------------- | |
| 1336 // Estimate block frequencies based on IfNode probabilities. | |
| 1337 void PhaseCFG::Estimate_Block_Frequency() { | |
| 418 | 1338 |
| 1339 // Force conditional branches leading to uncommon traps to be unlikely, | |
| 1340 // not because we get to the uncommon_trap with less relative frequency, | |
| 1341 // but because an uncommon_trap typically causes a deopt, so we only get | |
| 1342 // there once. | |
| 1343 if (C->do_freq_based_layout()) { | |
| 1344 Block_List worklist; | |
| 1345 Block* root_blk = _blocks[0]; | |
| 1346 for (uint i = 1; i < root_blk->num_preds(); i++) { | |
| 1347 Block *pb = _bbs[root_blk->pred(i)->_idx]; | |
| 1348 if (pb->has_uncommon_code()) { | |
| 1349 worklist.push(pb); | |
| 1350 } | |
| 1351 } | |
| 1352 while (worklist.size() > 0) { | |
| 1353 Block* uct = worklist.pop(); | |
| 1354 if (uct == _broot) continue; | |
| 1355 for (uint i = 1; i < uct->num_preds(); i++) { | |
| 1356 Block *pb = _bbs[uct->pred(i)->_idx]; | |
| 1357 if (pb->_num_succs == 1) { | |
| 1358 worklist.push(pb); | |
| 1359 } else if (pb->num_fall_throughs() == 2) { | |
| 1360 pb->update_uncommon_branch(uct); | |
| 1361 } | |
| 1362 } | |
| 1363 } | |
| 1364 } | |
| 0 | 1365 |
| 1366 // Create the loop tree and calculate loop depth. | |
| 1367 _root_loop = create_loop_tree(); | |
| 1368 _root_loop->compute_loop_depth(0); | |
| 1369 | |
| 1370 // Compute block frequency of each block, relative to a single loop entry. | |
| 1371 _root_loop->compute_freq(); | |
| 1372 | |
| 1373 // Adjust all frequencies to be relative to a single method entry | |
| 418 | 1374 _root_loop->_freq = 1.0; |
| 0 | 1375 _root_loop->scale_freq(); |
| 1376 | |
| 1377 // force paths ending at uncommon traps to be infrequent | |
| 418 | 1378 if (!C->do_freq_based_layout()) { |
| 1379 Block_List worklist; | |
| 1380 Block* root_blk = _blocks[0]; | |
| 1381 for (uint i = 1; i < root_blk->num_preds(); i++) { | |
| 1382 Block *pb = _bbs[root_blk->pred(i)->_idx]; | |
| 1383 if (pb->has_uncommon_code()) { | |
| 1384 worklist.push(pb); | |
| 1385 } | |
| 0 | 1386 } |
| 418 | 1387 while (worklist.size() > 0) { |
| 1388 Block* uct = worklist.pop(); | |
| 1389 uct->_freq = PROB_MIN; | |
| 1390 for (uint i = 1; i < uct->num_preds(); i++) { | |
| 1391 Block *pb = _bbs[uct->pred(i)->_idx]; | |
| 1392 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { | |
| 1393 worklist.push(pb); | |
| 1394 } | |
| 0 | 1395 } |
| 1396 } | |
| 1397 } | |
| 1398 | |
|
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1399 #ifdef ASSERT |
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1400 for (uint i = 0; i < _num_blocks; i++ ) { |
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1401 Block *b = _blocks[i]; |
| 605 | 1402 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency"); |
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1403 } |
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1404 #endif |
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1405 |
| 0 | 1406 #ifndef PRODUCT |
| 1407 if (PrintCFGBlockFreq) { | |
| 1408 tty->print_cr("CFG Block Frequencies"); | |
| 1409 _root_loop->dump_tree(); | |
| 1410 if (Verbose) { | |
| 1411 tty->print_cr("PhaseCFG dump"); | |
| 1412 dump(); | |
| 1413 tty->print_cr("Node dump"); | |
| 1414 _root->dump(99999); | |
| 1415 } | |
| 1416 } | |
| 1417 #endif | |
| 1418 } | |
| 1419 | |
| 1420 //----------------------------create_loop_tree-------------------------------- | |
| 1421 // Create a loop tree from the CFG | |
| 1422 CFGLoop* PhaseCFG::create_loop_tree() { | |
| 1423 | |
| 1424 #ifdef ASSERT | |
| 1425 assert( _blocks[0] == _broot, "" ); | |
| 1426 for (uint i = 0; i < _num_blocks; i++ ) { | |
| 1427 Block *b = _blocks[i]; | |
| 1428 // Check that _loop field are clear...we could clear them if not. | |
| 1429 assert(b->_loop == NULL, "clear _loop expected"); | |
| 1430 // Sanity check that the RPO numbering is reflected in the _blocks array. | |
| 1431 // It doesn't have to be for the loop tree to be built, but if it is not, | |
| 1432 // then the blocks have been reordered since dom graph building...which | |
| 1433 // may question the RPO numbering | |
| 1434 assert(b->_rpo == i, "unexpected reverse post order number"); | |
| 1435 } | |
| 1436 #endif | |
| 1437 | |
| 1438 int idct = 0; | |
| 1439 CFGLoop* root_loop = new CFGLoop(idct++); | |
| 1440 | |
| 1441 Block_List worklist; | |
| 1442 | |
| 1443 // Assign blocks to loops | |
| 1444 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block | |
| 1445 Block *b = _blocks[i]; | |
| 1446 | |
| 1447 if (b->head()->is_Loop()) { | |
| 1448 Block* loop_head = b; | |
| 1449 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
| 1450 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); | |
| 1451 Block* tail = _bbs[tail_n->_idx]; | |
| 1452 | |
| 1453 // Defensively filter out Loop nodes for non-single-entry loops. | |
| 1454 // For all reasonable loops, the head occurs before the tail in RPO. | |
| 1455 if (i <= tail->_rpo) { | |
| 1456 | |
| 1457 // The tail and (recursive) predecessors of the tail | |
| 1458 // are made members of a new loop. | |
| 1459 | |
| 1460 assert(worklist.size() == 0, "nonempty worklist"); | |
| 1461 CFGLoop* nloop = new CFGLoop(idct++); | |
| 1462 assert(loop_head->_loop == NULL, "just checking"); | |
| 1463 loop_head->_loop = nloop; | |
| 1464 // Add to nloop so push_pred() will skip over inner loops | |
| 1465 nloop->add_member(loop_head); | |
| 1466 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs); | |
| 1467 | |
| 1468 while (worklist.size() > 0) { | |
| 1469 Block* member = worklist.pop(); | |
| 1470 if (member != loop_head) { | |
| 1471 for (uint j = 1; j < member->num_preds(); j++) { | |
| 1472 nloop->push_pred(member, j, worklist, _bbs); | |
| 1473 } | |
| 1474 } | |
| 1475 } | |
| 1476 } | |
| 1477 } | |
| 1478 } | |
| 1479 | |
| 1480 // Create a member list for each loop consisting | |
| 1481 // of both blocks and (immediate child) loops. | |
| 1482 for (uint i = 0; i < _num_blocks; i++) { | |
| 1483 Block *b = _blocks[i]; | |
| 1484 CFGLoop* lp = b->_loop; | |
| 1485 if (lp == NULL) { | |
| 1486 // Not assigned to a loop. Add it to the method's pseudo loop. | |
| 1487 b->_loop = root_loop; | |
| 1488 lp = root_loop; | |
| 1489 } | |
| 1490 if (lp == root_loop || b != lp->head()) { // loop heads are already members | |
| 1491 lp->add_member(b); | |
| 1492 } | |
| 1493 if (lp != root_loop) { | |
| 1494 if (lp->parent() == NULL) { | |
| 1495 // Not a nested loop. Make it a child of the method's pseudo loop. | |
| 1496 root_loop->add_nested_loop(lp); | |
| 1497 } | |
| 1498 if (b == lp->head()) { | |
| 1499 // Add nested loop to member list of parent loop. | |
| 1500 lp->parent()->add_member(lp); | |
| 1501 } | |
| 1502 } | |
| 1503 } | |
| 1504 | |
| 1505 return root_loop; | |
| 1506 } | |
| 1507 | |
| 1508 //------------------------------push_pred-------------------------------------- | |
| 1509 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) { | |
| 1510 Node* pred_n = blk->pred(i); | |
| 1511 Block* pred = node_to_blk[pred_n->_idx]; | |
| 1512 CFGLoop *pred_loop = pred->_loop; | |
| 1513 if (pred_loop == NULL) { | |
| 1514 // Filter out blocks for non-single-entry loops. | |
| 1515 // For all reasonable loops, the head occurs before the tail in RPO. | |
| 1516 if (pred->_rpo > head()->_rpo) { | |
| 1517 pred->_loop = this; | |
| 1518 worklist.push(pred); | |
| 1519 } | |
| 1520 } else if (pred_loop != this) { | |
| 1521 // Nested loop. | |
| 1522 while (pred_loop->_parent != NULL && pred_loop->_parent != this) { | |
| 1523 pred_loop = pred_loop->_parent; | |
| 1524 } | |
| 1525 // Make pred's loop be a child | |
| 1526 if (pred_loop->_parent == NULL) { | |
| 1527 add_nested_loop(pred_loop); | |
| 1528 // Continue with loop entry predecessor. | |
| 1529 Block* pred_head = pred_loop->head(); | |
| 1530 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
| 1531 assert(pred_head != head(), "loop head in only one loop"); | |
| 1532 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk); | |
| 1533 } else { | |
| 1534 assert(pred_loop->_parent == this && _parent == NULL, "just checking"); | |
| 1535 } | |
| 1536 } | |
| 1537 } | |
| 1538 | |
| 1539 //------------------------------add_nested_loop-------------------------------- | |
| 1540 // Make cl a child of the current loop in the loop tree. | |
| 1541 void CFGLoop::add_nested_loop(CFGLoop* cl) { | |
| 1542 assert(_parent == NULL, "no parent yet"); | |
| 1543 assert(cl != this, "not my own parent"); | |
| 1544 cl->_parent = this; | |
| 1545 CFGLoop* ch = _child; | |
| 1546 if (ch == NULL) { | |
| 1547 _child = cl; | |
| 1548 } else { | |
| 1549 while (ch->_sibling != NULL) { ch = ch->_sibling; } | |
| 1550 ch->_sibling = cl; | |
| 1551 } | |
| 1552 } | |
| 1553 | |
| 1554 //------------------------------compute_loop_depth----------------------------- | |
| 1555 // Store the loop depth in each CFGLoop object. | |
| 1556 // Recursively walk the children to do the same for them. | |
| 1557 void CFGLoop::compute_loop_depth(int depth) { | |
| 1558 _depth = depth; | |
| 1559 CFGLoop* ch = _child; | |
| 1560 while (ch != NULL) { | |
| 1561 ch->compute_loop_depth(depth + 1); | |
| 1562 ch = ch->_sibling; | |
| 1563 } | |
| 1564 } | |
| 1565 | |
| 1566 //------------------------------compute_freq----------------------------------- | |
| 1567 // Compute the frequency of each block and loop, relative to a single entry | |
| 1568 // into the dominating loop head. | |
| 1569 void CFGLoop::compute_freq() { | |
| 1570 // Bottom up traversal of loop tree (visit inner loops first.) | |
| 1571 // Set loop head frequency to 1.0, then transitively | |
| 1572 // compute frequency for all successors in the loop, | |
| 1573 // as well as for each exit edge. Inner loops are | |
| 1574 // treated as single blocks with loop exit targets | |
| 1575 // as the successor blocks. | |
| 1576 | |
| 1577 // Nested loops first | |
| 1578 CFGLoop* ch = _child; | |
| 1579 while (ch != NULL) { | |
| 1580 ch->compute_freq(); | |
| 1581 ch = ch->_sibling; | |
| 1582 } | |
| 1583 assert (_members.length() > 0, "no empty loops"); | |
| 1584 Block* hd = head(); | |
| 1585 hd->_freq = 1.0f; | |
| 1586 for (int i = 0; i < _members.length(); i++) { | |
| 1587 CFGElement* s = _members.at(i); | |
| 1588 float freq = s->_freq; | |
| 1589 if (s->is_block()) { | |
| 1590 Block* b = s->as_Block(); | |
| 1591 for (uint j = 0; j < b->_num_succs; j++) { | |
| 1592 Block* sb = b->_succs[j]; | |
| 1593 update_succ_freq(sb, freq * b->succ_prob(j)); | |
| 1594 } | |
| 1595 } else { | |
| 1596 CFGLoop* lp = s->as_CFGLoop(); | |
| 1597 assert(lp->_parent == this, "immediate child"); | |
| 1598 for (int k = 0; k < lp->_exits.length(); k++) { | |
| 1599 Block* eb = lp->_exits.at(k).get_target(); | |
| 1600 float prob = lp->_exits.at(k).get_prob(); | |
| 1601 update_succ_freq(eb, freq * prob); | |
| 1602 } | |
| 1603 } | |
| 1604 } | |
| 1605 | |
| 1606 // For all loops other than the outer, "method" loop, | |
| 1607 // sum and normalize the exit probability. The "method" loop | |
| 1608 // should keep the initial exit probability of 1, so that | |
| 1609 // inner blocks do not get erroneously scaled. | |
| 1610 if (_depth != 0) { | |
| 1611 // Total the exit probabilities for this loop. | |
| 1612 float exits_sum = 0.0f; | |
| 1613 for (int i = 0; i < _exits.length(); i++) { | |
| 1614 exits_sum += _exits.at(i).get_prob(); | |
| 1615 } | |
| 1616 | |
| 1617 // Normalize the exit probabilities. Until now, the | |
| 1618 // probabilities estimate the possibility of exit per | |
| 1619 // a single loop iteration; afterward, they estimate | |
| 1620 // the probability of exit per loop entry. | |
| 1621 for (int i = 0; i < _exits.length(); i++) { | |
| 1622 Block* et = _exits.at(i).get_target(); | |
| 418 | 1623 float new_prob = 0.0f; |
| 1624 if (_exits.at(i).get_prob() > 0.0f) { | |
| 1625 new_prob = _exits.at(i).get_prob() / exits_sum; | |
| 1626 } | |
| 0 | 1627 BlockProbPair bpp(et, new_prob); |
| 1628 _exits.at_put(i, bpp); | |
| 1629 } | |
| 1630 | |
| 418 | 1631 // Save the total, but guard against unreasonable probability, |
| 0 | 1632 // as the value is used to estimate the loop trip count. |
| 1633 // An infinite trip count would blur relative block | |
| 1634 // frequencies. | |
| 1635 if (exits_sum > 1.0f) exits_sum = 1.0; | |
| 1636 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN; | |
| 1637 _exit_prob = exits_sum; | |
| 1638 } | |
| 1639 } | |
| 1640 | |
| 1641 //------------------------------succ_prob------------------------------------- | |
| 1642 // Determine the probability of reaching successor 'i' from the receiver block. | |
| 1643 float Block::succ_prob(uint i) { | |
| 1644 int eidx = end_idx(); | |
| 1645 Node *n = _nodes[eidx]; // Get ending Node | |
| 308 | 1646 |
| 1647 int op = n->Opcode(); | |
| 1648 if (n->is_Mach()) { | |
| 1649 if (n->is_MachNullCheck()) { | |
| 1650 // Can only reach here if called after lcm. The original Op_If is gone, | |
| 1651 // so we attempt to infer the probability from one or both of the | |
| 1652 // successor blocks. | |
| 1653 assert(_num_succs == 2, "expecting 2 successors of a null check"); | |
| 1654 // If either successor has only one predecessor, then the | |
| 605 | 1655 // probability estimate can be derived using the |
| 308 | 1656 // relative frequency of the successor and this block. |
| 1657 if (_succs[i]->num_preds() == 2) { | |
| 1658 return _succs[i]->_freq / _freq; | |
| 1659 } else if (_succs[1-i]->num_preds() == 2) { | |
| 1660 return 1 - (_succs[1-i]->_freq / _freq); | |
| 1661 } else { | |
| 1662 // Estimate using both successor frequencies | |
| 1663 float freq = _succs[i]->_freq; | |
| 1664 return freq / (freq + _succs[1-i]->_freq); | |
| 1665 } | |
| 1666 } | |
| 1667 op = n->as_Mach()->ideal_Opcode(); | |
| 1668 } | |
| 1669 | |
| 0 | 1670 |
| 1671 // Switch on branch type | |
| 1672 switch( op ) { | |
| 1673 case Op_CountedLoopEnd: | |
| 1674 case Op_If: { | |
| 1675 assert (i < 2, "just checking"); | |
| 1676 // Conditionals pass on only part of their frequency | |
| 1677 float prob = n->as_MachIf()->_prob; | |
| 1678 assert(prob >= 0.0 && prob <= 1.0, "out of range probability"); | |
| 1679 // If succ[i] is the FALSE branch, invert path info | |
| 1680 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) { | |
| 1681 return 1.0f - prob; // not taken | |
| 1682 } else { | |
| 1683 return prob; // taken | |
| 1684 } | |
| 1685 } | |
| 1686 | |
| 1687 case Op_Jump: | |
| 1688 // Divide the frequency between all successors evenly | |
| 1689 return 1.0f/_num_succs; | |
| 1690 | |
| 1691 case Op_Catch: { | |
| 1692 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); | |
| 1693 if (ci->_con == CatchProjNode::fall_through_index) { | |
| 1694 // Fall-thru path gets the lion's share. | |
| 1695 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs; | |
| 1696 } else { | |
| 1697 // Presume exceptional paths are equally unlikely | |
| 1698 return PROB_UNLIKELY_MAG(5); | |
| 1699 } | |
| 1700 } | |
| 1701 | |
| 1702 case Op_Root: | |
| 1703 case Op_Goto: | |
| 1704 // Pass frequency straight thru to target | |
| 1705 return 1.0f; | |
| 1706 | |
| 1707 case Op_NeverBranch: | |
| 1708 return 0.0f; | |
| 1709 | |
| 1710 case Op_TailCall: | |
| 1711 case Op_TailJump: | |
| 1712 case Op_Return: | |
| 1713 case Op_Halt: | |
| 1714 case Op_Rethrow: | |
| 1715 // Do not push out freq to root block | |
| 1716 return 0.0f; | |
| 1717 | |
| 1718 default: | |
| 1719 ShouldNotReachHere(); | |
| 1720 } | |
| 1721 | |
| 1722 return 0.0f; | |
| 1723 } | |
| 1724 | |
| 418 | 1725 //------------------------------num_fall_throughs----------------------------- |
| 1726 // Return the number of fall-through candidates for a block | |
| 1727 int Block::num_fall_throughs() { | |
| 1728 int eidx = end_idx(); | |
| 1729 Node *n = _nodes[eidx]; // Get ending Node | |
| 1730 | |
| 1731 int op = n->Opcode(); | |
| 1732 if (n->is_Mach()) { | |
| 1733 if (n->is_MachNullCheck()) { | |
| 1734 // In theory, either side can fall-thru, for simplicity sake, | |
| 1735 // let's say only the false branch can now. | |
| 1736 return 1; | |
| 1737 } | |
| 1738 op = n->as_Mach()->ideal_Opcode(); | |
| 1739 } | |
| 1740 | |
| 1741 // Switch on branch type | |
| 1742 switch( op ) { | |
| 1743 case Op_CountedLoopEnd: | |
| 1744 case Op_If: | |
| 1745 return 2; | |
| 1746 | |
| 1747 case Op_Root: | |
| 1748 case Op_Goto: | |
| 1749 return 1; | |
| 1750 | |
| 1751 case Op_Catch: { | |
| 1752 for (uint i = 0; i < _num_succs; i++) { | |
| 1753 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); | |
| 1754 if (ci->_con == CatchProjNode::fall_through_index) { | |
| 1755 return 1; | |
| 1756 } | |
| 1757 } | |
| 1758 return 0; | |
| 1759 } | |
| 1760 | |
| 1761 case Op_Jump: | |
| 1762 case Op_NeverBranch: | |
| 1763 case Op_TailCall: | |
| 1764 case Op_TailJump: | |
| 1765 case Op_Return: | |
| 1766 case Op_Halt: | |
| 1767 case Op_Rethrow: | |
| 1768 return 0; | |
| 1769 | |
| 1770 default: | |
| 1771 ShouldNotReachHere(); | |
| 1772 } | |
| 1773 | |
| 1774 return 0; | |
| 1775 } | |
| 1776 | |
| 1777 //------------------------------succ_fall_through----------------------------- | |
| 1778 // Return true if a specific successor could be fall-through target. | |
| 1779 bool Block::succ_fall_through(uint i) { | |
| 1780 int eidx = end_idx(); | |
| 1781 Node *n = _nodes[eidx]; // Get ending Node | |
| 1782 | |
| 1783 int op = n->Opcode(); | |
| 1784 if (n->is_Mach()) { | |
| 1785 if (n->is_MachNullCheck()) { | |
| 1786 // In theory, either side can fall-thru, for simplicity sake, | |
| 1787 // let's say only the false branch can now. | |
| 1788 return _nodes[i + eidx + 1]->Opcode() == Op_IfFalse; | |
| 1789 } | |
| 1790 op = n->as_Mach()->ideal_Opcode(); | |
| 1791 } | |
| 1792 | |
| 1793 // Switch on branch type | |
| 1794 switch( op ) { | |
| 1795 case Op_CountedLoopEnd: | |
| 1796 case Op_If: | |
| 1797 case Op_Root: | |
| 1798 case Op_Goto: | |
| 1799 return true; | |
| 1800 | |
| 1801 case Op_Catch: { | |
| 1802 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); | |
| 1803 return ci->_con == CatchProjNode::fall_through_index; | |
| 1804 } | |
| 1805 | |
| 1806 case Op_Jump: | |
| 1807 case Op_NeverBranch: | |
| 1808 case Op_TailCall: | |
| 1809 case Op_TailJump: | |
| 1810 case Op_Return: | |
| 1811 case Op_Halt: | |
| 1812 case Op_Rethrow: | |
| 1813 return false; | |
| 1814 | |
| 1815 default: | |
| 1816 ShouldNotReachHere(); | |
| 1817 } | |
| 1818 | |
| 1819 return false; | |
| 1820 } | |
| 1821 | |
| 1822 //------------------------------update_uncommon_branch------------------------ | |
| 1823 // Update the probability of a two-branch to be uncommon | |
| 1824 void Block::update_uncommon_branch(Block* ub) { | |
| 1825 int eidx = end_idx(); | |
| 1826 Node *n = _nodes[eidx]; // Get ending Node | |
| 1827 | |
| 1828 int op = n->as_Mach()->ideal_Opcode(); | |
| 1829 | |
| 1830 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If"); | |
| 1831 assert(num_fall_throughs() == 2, "must be a two way branch block"); | |
| 1832 | |
| 1833 // Which successor is ub? | |
| 1834 uint s; | |
| 1835 for (s = 0; s <_num_succs; s++) { | |
| 1836 if (_succs[s] == ub) break; | |
| 1837 } | |
| 1838 assert(s < 2, "uncommon successor must be found"); | |
| 1839 | |
| 1840 // If ub is the true path, make the proability small, else | |
| 1841 // ub is the false path, and make the probability large | |
| 1842 bool invert = (_nodes[s + eidx + 1]->Opcode() == Op_IfFalse); | |
| 1843 | |
| 1844 // Get existing probability | |
| 1845 float p = n->as_MachIf()->_prob; | |
| 1846 | |
| 1847 if (invert) p = 1.0 - p; | |
| 1848 if (p > PROB_MIN) { | |
| 1849 p = PROB_MIN; | |
| 1850 } | |
| 1851 if (invert) p = 1.0 - p; | |
| 1852 | |
| 1853 n->as_MachIf()->_prob = p; | |
| 1854 } | |
| 1855 | |
| 0 | 1856 //------------------------------update_succ_freq------------------------------- |
| 605 | 1857 // Update the appropriate frequency associated with block 'b', a successor of |
| 0 | 1858 // a block in this loop. |
| 1859 void CFGLoop::update_succ_freq(Block* b, float freq) { | |
| 1860 if (b->_loop == this) { | |
| 1861 if (b == head()) { | |
| 1862 // back branch within the loop | |
| 1863 // Do nothing now, the loop carried frequency will be | |
| 1864 // adjust later in scale_freq(). | |
| 1865 } else { | |
| 1866 // simple branch within the loop | |
| 1867 b->_freq += freq; | |
| 1868 } | |
| 1869 } else if (!in_loop_nest(b)) { | |
| 1870 // branch is exit from this loop | |
| 1871 BlockProbPair bpp(b, freq); | |
| 1872 _exits.append(bpp); | |
| 1873 } else { | |
| 1874 // branch into nested loop | |
| 1875 CFGLoop* ch = b->_loop; | |
| 1876 ch->_freq += freq; | |
| 1877 } | |
| 1878 } | |
| 1879 | |
| 1880 //------------------------------in_loop_nest----------------------------------- | |
| 1881 // Determine if block b is in the receiver's loop nest. | |
| 1882 bool CFGLoop::in_loop_nest(Block* b) { | |
| 1883 int depth = _depth; | |
| 1884 CFGLoop* b_loop = b->_loop; | |
| 1885 int b_depth = b_loop->_depth; | |
| 1886 if (depth == b_depth) { | |
| 1887 return true; | |
| 1888 } | |
| 1889 while (b_depth > depth) { | |
| 1890 b_loop = b_loop->_parent; | |
| 1891 b_depth = b_loop->_depth; | |
| 1892 } | |
| 1893 return b_loop == this; | |
| 1894 } | |
| 1895 | |
| 1896 //------------------------------scale_freq------------------------------------- | |
| 1897 // Scale frequency of loops and blocks by trip counts from outer loops | |
| 1898 // Do a top down traversal of loop tree (visit outer loops first.) | |
| 1899 void CFGLoop::scale_freq() { | |
| 1900 float loop_freq = _freq * trip_count(); | |
| 1901 for (int i = 0; i < _members.length(); i++) { | |
| 1902 CFGElement* s = _members.at(i); | |
|
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1903 float block_freq = s->_freq * loop_freq; |
| 621 | 1904 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY) |
| 1905 block_freq = MIN_BLOCK_FREQUENCY; | |
|
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1906 s->_freq = block_freq; |
| 0 | 1907 } |
| 1908 CFGLoop* ch = _child; | |
| 1909 while (ch != NULL) { | |
| 1910 ch->scale_freq(); | |
| 1911 ch = ch->_sibling; | |
| 1912 } | |
| 1913 } | |
| 1914 | |
| 1915 #ifndef PRODUCT | |
| 1916 //------------------------------dump_tree-------------------------------------- | |
| 1917 void CFGLoop::dump_tree() const { | |
| 1918 dump(); | |
| 1919 if (_child != NULL) _child->dump_tree(); | |
| 1920 if (_sibling != NULL) _sibling->dump_tree(); | |
| 1921 } | |
| 1922 | |
| 1923 //------------------------------dump------------------------------------------- | |
| 1924 void CFGLoop::dump() const { | |
| 1925 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1926 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n", | |
| 1927 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq); | |
| 1928 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1929 tty->print(" members:", _id); | |
| 1930 int k = 0; | |
| 1931 for (int i = 0; i < _members.length(); i++) { | |
| 1932 if (k++ >= 6) { | |
| 1933 tty->print("\n "); | |
| 1934 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
| 1935 k = 0; | |
| 1936 } | |
| 1937 CFGElement *s = _members.at(i); | |
| 1938 if (s->is_block()) { | |
| 1939 Block *b = s->as_Block(); | |
| 1940 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq); | |
| 1941 } else { | |
| 1942 CFGLoop* lp = s->as_CFGLoop(); | |
| 1943 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq); | |
| 1944 } | |
| 1945 } | |
| 1946 tty->print("\n"); | |
| 1947 for (int i = 0; i < _depth; i++) tty->print(" "); | |
| 1948 tty->print(" exits: "); | |
| 1949 k = 0; | |
| 1950 for (int i = 0; i < _exits.length(); i++) { | |
| 1951 if (k++ >= 7) { | |
| 1952 tty->print("\n "); | |
| 1953 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
| 1954 k = 0; | |
| 1955 } | |
| 1956 Block *blk = _exits.at(i).get_target(); | |
| 1957 float prob = _exits.at(i).get_prob(); | |
| 1958 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); | |
| 1959 } | |
| 1960 tty->print("\n"); | |
| 1961 } | |
| 1962 #endif |