1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
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 // To avoid float value underflow
33 #define MIN_BLOCK_FREQUENCY 1.e-35f
34
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
60
61 //------------------------------schedule_pinned_nodes--------------------------
62 // Set the basic block for Nodes pinned into blocks
63 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) {
64 // Allocate node stack of size C->unique()+8 to avoid frequent realloc
65 GrowableArray <Node *> spstack(C->unique()+8);
66 spstack.push(_root);
67 while ( spstack.is_nonempty() ) {
68 Node *n = spstack.pop();
69 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited
70 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down!
71 Node *input = n->in(0);
72 assert( input, "pinned Node must have Control" );
73 while( !input->is_block_start() )
74 input = input->in(0);
75 Block *b = _bbs[input->_idx]; // Basic block of controlling input
76 schedule_node_into_block(n, b);
77 }
78 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs
79 if( n->in(i) != NULL )
80 spstack.push(n->in(i));
81 }
82 }
83 }
84 }
85
86 #ifdef ASSERT
87 // Assert that new input b2 is dominated by all previous inputs.
88 // Check this by by seeing that it is dominated by b1, the deepest
89 // input observed until b2.
90 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) {
91 if (b1 == NULL) return;
92 assert(b1->_dom_depth < b2->_dom_depth, "sanity");
93 Block* tmp = b2;
94 while (tmp != b1 && tmp != NULL) {
95 tmp = tmp->_idom;
96 }
97 if (tmp != b1) {
98 // Detected an unschedulable graph. Print some nice stuff and die.
99 tty->print_cr("!!! Unschedulable graph !!!");
100 for (uint j=0; j<n->len(); j++) { // For all inputs
101 Node* inn = n->in(j); // Get input
102 if (inn == NULL) continue; // Ignore NULL, missing inputs
103 Block* inb = bbs[inn->_idx];
104 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order,
105 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth);
106 inn->dump();
107 }
108 tty->print("Failing node: ");
109 n->dump();
110 assert(false, "unscheduable graph");
111 }
112 }
113 #endif
114
115 static Block* find_deepest_input(Node* n, Block_Array &bbs) {
116 // Find the last input dominated by all other inputs.
117 Block* deepb = NULL; // Deepest block so far
118 int deepb_dom_depth = 0;
119 for (uint k = 0; k < n->len(); k++) { // For all inputs
120 Node* inn = n->in(k); // Get input
121 if (inn == NULL) continue; // Ignore NULL, missing inputs
122 Block* inb = bbs[inn->_idx];
123 assert(inb != NULL, "must already have scheduled this input");
124 if (deepb_dom_depth < (int) inb->_dom_depth) {
125 // The new inb must be dominated by the previous deepb.
126 // The various inputs must be linearly ordered in the dom
127 // tree, or else there will not be a unique deepest block.
128 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs));
129 deepb = inb; // Save deepest block
130 deepb_dom_depth = deepb->_dom_depth;
131 }
132 }
133 assert(deepb != NULL, "must be at least one input to n");
134 return deepb;
135 }
136
137
138 //------------------------------schedule_early---------------------------------
139 // Find the earliest Block any instruction can be placed in. Some instructions
140 // are pinned into Blocks. Unpinned instructions can appear in last block in
141 // which all their inputs occur.
142 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) {
143 // Allocate stack with enough space to avoid frequent realloc
144 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats
145 // roots.push(_root); _root will be processed among C->top() inputs
146 roots.push(C->top());
147 visited.set(C->top()->_idx);
148
149 while (roots.size() != 0) {
150 // Use local variables nstack_top_n & nstack_top_i to cache values
151 // on stack's top.
152 Node *nstack_top_n = roots.pop();
153 uint nstack_top_i = 0;
154 //while_nstack_nonempty:
155 while (true) {
156 // Get parent node and next input's index from stack's top.
157 Node *n = nstack_top_n;
158 uint i = nstack_top_i;
159
160 if (i == 0) {
161 // Special control input processing.
162 // While I am here, go ahead and look for Nodes which are taking control
163 // from a is_block_proj Node. After I inserted RegionNodes to make proper
164 // blocks, the control at a is_block_proj more properly comes from the
165 // Region being controlled by the block_proj Node.
166 const Node *in0 = n->in(0);
167 if (in0 != NULL) { // Control-dependent?
168 const Node *p = in0->is_block_proj();
169 if (p != NULL && p != n) { // Control from a block projection?
170 // Find trailing Region
171 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block
172 uint j = 0;
173 if (pb->_num_succs != 1) { // More then 1 successor?
174 // Search for successor
175 uint max = pb->_nodes.size();
176 assert( max > 1, "" );
177 uint start = max - pb->_num_succs;
178 // Find which output path belongs to projection
179 for (j = start; j < max; j++) {
180 if( pb->_nodes[j] == in0 )
181 break;
182 }
183 assert( j < max, "must find" );
184 // Change control to match head of successor basic block
185 j -= start;
186 }
187 n->set_req(0, pb->_succs[j]->head());
188 }
189 } else { // n->in(0) == NULL
190 if (n->req() == 1) { // This guy is a constant with NO inputs?
191 n->set_req(0, _root);
192 }
193 }
194 }
195
196 // First, visit all inputs and force them to get a block. If an
197 // input is already in a block we quit following inputs (to avoid
198 // cycles). Instead we put that Node on a worklist to be handled
199 // later (since IT'S inputs may not have a block yet).
200 bool done = true; // Assume all n's inputs will be processed
201 while (i < n->len()) { // For all inputs
202 Node *in = n->in(i); // Get input
203 ++i;
204 if (in == NULL) continue; // Ignore NULL, missing inputs
205 int is_visited = visited.test_set(in->_idx);
206 if (!_bbs.lookup(in->_idx)) { // Missing block selection?
207 if (is_visited) {
208 // assert( !visited.test(in->_idx), "did not schedule early" );
209 return false;
210 }
211 nstack.push(n, i); // Save parent node and next input's index.
212 nstack_top_n = in; // Process current input now.
213 nstack_top_i = 0;
214 done = false; // Not all n's inputs processed.
215 break; // continue while_nstack_nonempty;
216 } else if (!is_visited) { // Input not yet visited?
217 roots.push(in); // Visit this guy later, using worklist
218 }
219 }
220 if (done) {
221 // All of n's inputs have been processed, complete post-processing.
222
223 // Some instructions are pinned into a block. These include Region,
224 // Phi, Start, Return, and other control-dependent instructions and
225 // any projections which depend on them.
226 if (!n->pinned()) {
227 // Set earliest legal block.
228 _bbs.map(n->_idx, find_deepest_input(n, _bbs));
229 }
230
231 if (nstack.is_empty()) {
232 // Finished all nodes on stack.
233 // Process next node on the worklist 'roots'.
234 break;
235 }
236 // Get saved parent node and next input's index.
237 nstack_top_n = nstack.node();
238 nstack_top_i = nstack.index();
239 nstack.pop();
240 } // if (done)
241 } // while (true)
242 } // while (roots.size() != 0)
243 return true;
244 }
245
246 //------------------------------dom_lca----------------------------------------
247 // Find least common ancestor in dominator tree
248 // LCA is a current notion of LCA, to be raised above 'this'.
249 // As a convenient boundary condition, return 'this' if LCA is NULL.
250 // Find the LCA of those two nodes.
251 Block* Block::dom_lca(Block* LCA) {
252 if (LCA == NULL || LCA == this) return this;
253
254 Block* anc = this;
255 while (anc->_dom_depth > LCA->_dom_depth)
256 anc = anc->_idom; // Walk up till anc is as high as LCA
257
258 while (LCA->_dom_depth > anc->_dom_depth)
259 LCA = LCA->_idom; // Walk up till LCA is as high as anc
260
261 while (LCA != anc) { // Walk both up till they are the same
262 LCA = LCA->_idom;
263 anc = anc->_idom;
264 }
265
266 return LCA;
267 }
268
269 //--------------------------raise_LCA_above_use--------------------------------
270 // We are placing a definition, and have been given a def->use edge.
271 // The definition must dominate the use, so move the LCA upward in the
272 // dominator tree to dominate the use. If the use is a phi, adjust
273 // the LCA only with the phi input paths which actually use this def.
274 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) {
275 Block* buse = bbs[use->_idx];
276 if (buse == NULL) return LCA; // Unused killing Projs have no use block
277 if (!use->is_Phi()) return buse->dom_lca(LCA);
278 uint pmax = use->req(); // Number of Phi inputs
279 // Why does not this loop just break after finding the matching input to
280 // the Phi? Well...it's like this. I do not have true def-use/use-def
281 // chains. Means I cannot distinguish, from the def-use direction, which
282 // of many use-defs lead from the same use to the same def. That is, this
283 // Phi might have several uses of the same def. Each use appears in a
284 // different predecessor block. But when I enter here, I cannot distinguish
285 // which use-def edge I should find the predecessor block for. So I find
286 // them all. Means I do a little extra work if a Phi uses the same value
287 // more than once.
288 for (uint j=1; j<pmax; j++) { // For all inputs
289 if (use->in(j) == def) { // Found matching input?
290 Block* pred = bbs[buse->pred(j)->_idx];
291 LCA = pred->dom_lca(LCA);
292 }
293 }
294 return LCA;
295 }
296
297 //----------------------------raise_LCA_above_marks----------------------------
298 // Return a new LCA that dominates LCA and any of its marked predecessors.
299 // Search all my parents up to 'early' (exclusive), looking for predecessors
300 // which are marked with the given index. Return the LCA (in the dom tree)
301 // of all marked blocks. If there are none marked, return the original
302 // LCA.
303 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark,
304 Block* early, Block_Array &bbs) {
305 Block_List worklist;
306 worklist.push(LCA);
307 while (worklist.size() > 0) {
308 Block* mid = worklist.pop();
309 if (mid == early) continue; // stop searching here
310
311 // Test and set the visited bit.
312 if (mid->raise_LCA_visited() == mark) continue; // already visited
313
314 // Don't process the current LCA, otherwise the search may terminate early
315 if (mid != LCA && mid->raise_LCA_mark() == mark) {
316 // Raise the LCA.
317 LCA = mid->dom_lca(LCA);
318 if (LCA == early) break; // stop searching everywhere
319 assert(early->dominates(LCA), "early is high enough");
320 // Resume searching at that point, skipping intermediate levels.
321 worklist.push(LCA);
322 if (LCA == mid)
323 continue; // Don't mark as visited to avoid early termination.
324 } else {
325 // Keep searching through this block's predecessors.
326 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) {
327 Block* mid_parent = bbs[ mid->pred(j)->_idx ];
328 worklist.push(mid_parent);
329 }
330 }
331 mid->set_raise_LCA_visited(mark);
332 }
333 return LCA;
334 }
335
336 //--------------------------memory_early_block--------------------------------
337 // This is a variation of find_deepest_input, the heart of schedule_early.
338 // Find the "early" block for a load, if we considered only memory and
339 // address inputs, that is, if other data inputs were ignored.
340 //
341 // Because a subset of edges are considered, the resulting block will
342 // be earlier (at a shallower dom_depth) than the true schedule_early
343 // point of the node. We compute this earlier block as a more permissive
344 // site for anti-dependency insertion, but only if subsume_loads is enabled.
345 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) {
346 Node* base;
347 Node* index;
348 Node* store = load->in(MemNode::Memory);
349 load->as_Mach()->memory_inputs(base, index);
350
351 assert(base != NodeSentinel && index != NodeSentinel,
352 "unexpected base/index inputs");
353
354 Node* mem_inputs[4];
355 int mem_inputs_length = 0;
356 if (base != NULL) mem_inputs[mem_inputs_length++] = base;
357 if (index != NULL) mem_inputs[mem_inputs_length++] = index;
358 if (store != NULL) mem_inputs[mem_inputs_length++] = store;
359
360 // In the comparision below, add one to account for the control input,
361 // which may be null, but always takes up a spot in the in array.
362 if (mem_inputs_length + 1 < (int) load->req()) {
363 // This "load" has more inputs than just the memory, base and index inputs.
364 // For purposes of checking anti-dependences, we need to start
365 // from the early block of only the address portion of the instruction,
366 // and ignore other blocks that may have factored into the wider
367 // schedule_early calculation.
368 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0);
369
370 Block* deepb = NULL; // Deepest block so far
371 int deepb_dom_depth = 0;
372 for (int i = 0; i < mem_inputs_length; i++) {
373 Block* inb = bbs[mem_inputs[i]->_idx];
374 if (deepb_dom_depth < (int) inb->_dom_depth) {
375 // The new inb must be dominated by the previous deepb.
376 // The various inputs must be linearly ordered in the dom
377 // tree, or else there will not be a unique deepest block.
378 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs));
379 deepb = inb; // Save deepest block
380 deepb_dom_depth = deepb->_dom_depth;
381 }
382 }
383 early = deepb;
384 }
385
386 return early;
387 }
388
389 //--------------------------insert_anti_dependences---------------------------
390 // A load may need to witness memory that nearby stores can overwrite.
391 // For each nearby store, either insert an "anti-dependence" edge
392 // from the load to the store, or else move LCA upward to force the
393 // load to (eventually) be scheduled in a block above the store.
394 //
395 // Do not add edges to stores on distinct control-flow paths;
396 // only add edges to stores which might interfere.
397 //
398 // Return the (updated) LCA. There will not be any possibly interfering
399 // store between the load's "early block" and the updated LCA.
400 // Any stores in the updated LCA will have new precedence edges
401 // back to the load. The caller is expected to schedule the load
402 // in the LCA, in which case the precedence edges will make LCM
403 // preserve anti-dependences. The caller may also hoist the load
404 // above the LCA, if it is not the early block.
405 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) {
406 assert(load->needs_anti_dependence_check(), "must be a load of some sort");
407 assert(LCA != NULL, "");
408 DEBUG_ONLY(Block* LCA_orig = LCA);
409
410 // Compute the alias index. Loads and stores with different alias indices
411 // do not need anti-dependence edges.
412 uint load_alias_idx = C->get_alias_index(load->adr_type());
413 #ifdef ASSERT
414 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 &&
415 (PrintOpto || VerifyAliases ||
416 PrintMiscellaneous && (WizardMode || Verbose))) {
417 // Load nodes should not consume all of memory.
418 // Reporting a bottom type indicates a bug in adlc.
419 // If some particular type of node validly consumes all of memory,
420 // sharpen the preceding "if" to exclude it, so we can catch bugs here.
421 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory.");
422 load->dump(2);
423 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, "");
424 }
425 #endif
426 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp),
427 "String compare is only known 'load' that does not conflict with any stores");
428
429 if (!C->alias_type(load_alias_idx)->is_rewritable()) {
430 // It is impossible to spoil this load by putting stores before it,
431 // because we know that the stores will never update the value
432 // which 'load' must witness.
433 return LCA;
434 }
435
436 node_idx_t load_index = load->_idx;
437
438 // Note the earliest legal placement of 'load', as determined by
439 // by the unique point in the dom tree where all memory effects
440 // and other inputs are first available. (Computed by schedule_early.)
441 // For normal loads, 'early' is the shallowest place (dom graph wise)
442 // to look for anti-deps between this load and any store.
443 Block* early = _bbs[load_index];
444
445 // If we are subsuming loads, compute an "early" block that only considers
446 // memory or address inputs. This block may be different than the
447 // schedule_early block in that it could be at an even shallower depth in the
448 // dominator tree, and allow for a broader discovery of anti-dependences.
449 if (C->subsume_loads()) {
450 early = memory_early_block(load, early, _bbs);
451 }
452
453 ResourceArea *area = Thread::current()->resource_area();
454 Node_List worklist_mem(area); // prior memory state to store
455 Node_List worklist_store(area); // possible-def to explore
456 Node_List worklist_visited(area); // visited mergemem nodes
457 Node_List non_early_stores(area); // all relevant stores outside of early
458 bool must_raise_LCA = false;
459
460 #ifdef TRACK_PHI_INPUTS
461 // %%% This extra checking fails because MergeMem nodes are not GVNed.
462 // Provide "phi_inputs" to check if every input to a PhiNode is from the
463 // original memory state. This indicates a PhiNode for which should not
464 // prevent the load from sinking. For such a block, set_raise_LCA_mark
465 // may be overly conservative.
466 // Mechanism: count inputs seen for each Phi encountered in worklist_store.
467 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0));
468 #endif
469
470 // 'load' uses some memory state; look for users of the same state.
471 // Recurse through MergeMem nodes to the stores that use them.
472
473 // Each of these stores is a possible definition of memory
474 // that 'load' needs to use. We need to force 'load'
475 // to occur before each such store. When the store is in
476 // the same block as 'load', we insert an anti-dependence
477 // edge load->store.
478
479 // The relevant stores "nearby" the load consist of a tree rooted
480 // at initial_mem, with internal nodes of type MergeMem.
481 // Therefore, the branches visited by the worklist are of this form:
482 // initial_mem -> (MergeMem ->)* store
483 // The anti-dependence constraints apply only to the fringe of this tree.
484
485 Node* initial_mem = load->in(MemNode::Memory);
486 worklist_store.push(initial_mem);
487 worklist_visited.push(initial_mem);
488 worklist_mem.push(NULL);
489 while (worklist_store.size() > 0) {
490 // Examine a nearby store to see if it might interfere with our load.
491 Node* mem = worklist_mem.pop();
492 Node* store = worklist_store.pop();
493 uint op = store->Opcode();
494
495 // MergeMems do not directly have anti-deps.
496 // Treat them as internal nodes in a forward tree of memory states,
497 // the leaves of which are each a 'possible-def'.
498 if (store == initial_mem // root (exclusive) of tree we are searching
499 || op == Op_MergeMem // internal node of tree we are searching
500 ) {
501 mem = store; // It's not a possibly interfering store.
502 if (store == initial_mem)
503 initial_mem = NULL; // only process initial memory once
504
505 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
506 store = mem->fast_out(i);
507 if (store->is_MergeMem()) {
508 // Be sure we don't get into combinatorial problems.
509 // (Allow phis to be repeated; they can merge two relevant states.)
510 uint j = worklist_visited.size();
511 for (; j > 0; j--) {
512 if (worklist_visited.at(j-1) == store) break;
513 }
514 if (j > 0) continue; // already on work list; do not repeat
515 worklist_visited.push(store);
516 }
517 worklist_mem.push(mem);
518 worklist_store.push(store);
519 }
520 continue;
521 }
522
523 if (op == Op_MachProj || op == Op_Catch) continue;
524 if (store->needs_anti_dependence_check()) continue; // not really a store
525
526 // Compute the alias index. Loads and stores with different alias
527 // indices do not need anti-dependence edges. Wide MemBar's are
528 // anti-dependent on everything (except immutable memories).
529 const TypePtr* adr_type = store->adr_type();
530 if (!C->can_alias(adr_type, load_alias_idx)) continue;
531
532 // Most slow-path runtime calls do NOT modify Java memory, but
533 // they can block and so write Raw memory.
534 if (store->is_Mach()) {
535 MachNode* mstore = store->as_Mach();
536 if (load_alias_idx != Compile::AliasIdxRaw) {
537 // Check for call into the runtime using the Java calling
538 // convention (and from there into a wrapper); it has no
539 // _method. Can't do this optimization for Native calls because
540 // they CAN write to Java memory.
541 if (mstore->ideal_Opcode() == Op_CallStaticJava) {
542 assert(mstore->is_MachSafePoint(), "");
543 MachSafePointNode* ms = (MachSafePointNode*) mstore;
544 assert(ms->is_MachCallJava(), "");
545 MachCallJavaNode* mcj = (MachCallJavaNode*) ms;
546 if (mcj->_method == NULL) {
547 // These runtime calls do not write to Java visible memory
548 // (other than Raw) and so do not require anti-dependence edges.
549 continue;
550 }
551 }
552 // Same for SafePoints: they read/write Raw but only read otherwise.
553 // This is basically a workaround for SafePoints only defining control
554 // instead of control + memory.
555 if (mstore->ideal_Opcode() == Op_SafePoint)
556 continue;
557 } else {
558 // Some raw memory, such as the load of "top" at an allocation,
559 // can be control dependent on the previous safepoint. See
560 // comments in GraphKit::allocate_heap() about control input.
561 // Inserting an anti-dep between such a safepoint and a use
562 // creates a cycle, and will cause a subsequent failure in
563 // local scheduling. (BugId 4919904)
564 // (%%% How can a control input be a safepoint and not a projection??)
565 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore)
566 continue;
567 }
568 }
569
570 // Identify a block that the current load must be above,
571 // or else observe that 'store' is all the way up in the
572 // earliest legal block for 'load'. In the latter case,
573 // immediately insert an anti-dependence edge.
574 Block* store_block = _bbs[store->_idx];
575 assert(store_block != NULL, "unused killing projections skipped above");
576
577 if (store->is_Phi()) {
578 // 'load' uses memory which is one (or more) of the Phi's inputs.
579 // It must be scheduled not before the Phi, but rather before
580 // each of the relevant Phi inputs.
581 //
582 // Instead of finding the LCA of all inputs to a Phi that match 'mem',
583 // we mark each corresponding predecessor block and do a combined
584 // hoisting operation later (raise_LCA_above_marks).
585 //
586 // Do not assert(store_block != early, "Phi merging memory after access")
587 // PhiNode may be at start of block 'early' with backedge to 'early'
588 DEBUG_ONLY(bool found_match = false);
589 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) {
590 if (store->in(j) == mem) { // Found matching input?
591 DEBUG_ONLY(found_match = true);
592 Block* pred_block = _bbs[store_block->pred(j)->_idx];
593 if (pred_block != early) {
594 // If any predecessor of the Phi matches the load's "early block",
595 // we do not need a precedence edge between the Phi and 'load'
596 // since the load will be forced into a block preceeding the Phi.
597 pred_block->set_raise_LCA_mark(load_index);
598 assert(!LCA_orig->dominates(pred_block) ||
599 early->dominates(pred_block), "early is high enough");
600 must_raise_LCA = true;
601 }
602 }
603 }
604 assert(found_match, "no worklist bug");
605 #ifdef TRACK_PHI_INPUTS
606 #ifdef ASSERT
607 // This assert asks about correct handling of PhiNodes, which may not
608 // have all input edges directly from 'mem'. See BugId 4621264
609 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1;
610 // Increment by exactly one even if there are multiple copies of 'mem'
611 // coming into the phi, because we will run this block several times
612 // if there are several copies of 'mem'. (That's how DU iterators work.)
613 phi_inputs.at_put(store->_idx, num_mem_inputs);
614 assert(PhiNode::Input + num_mem_inputs < store->req(),
615 "Expect at least one phi input will not be from original memory state");
616 #endif //ASSERT
617 #endif //TRACK_PHI_INPUTS
618 } else if (store_block != early) {
619 // 'store' is between the current LCA and earliest possible block.
620 // Label its block, and decide later on how to raise the LCA
621 // to include the effect on LCA of this store.
622 // If this store's block gets chosen as the raised LCA, we
623 // will find him on the non_early_stores list and stick him
624 // with a precedence edge.
625 // (But, don't bother if LCA is already raised all the way.)
626 if (LCA != early) {
627 store_block->set_raise_LCA_mark(load_index);
628 must_raise_LCA = true;
629 non_early_stores.push(store);
630 }
631 } else {
632 // Found a possibly-interfering store in the load's 'early' block.
633 // This means 'load' cannot sink at all in the dominator tree.
634 // Add an anti-dep edge, and squeeze 'load' into the highest block.
635 assert(store != load->in(0), "dependence cycle found");
636 if (verify) {
637 assert(store->find_edge(load) != -1, "missing precedence edge");
638 } else {
639 store->add_prec(load);
640 }
641 LCA = early;
642 // This turns off the process of gathering non_early_stores.
643 }
644 }
645 // (Worklist is now empty; all nearby stores have been visited.)
646
647 // Finished if 'load' must be scheduled in its 'early' block.
648 // If we found any stores there, they have already been given
649 // precedence edges.
650 if (LCA == early) return LCA;
651
652 // We get here only if there are no possibly-interfering stores
653 // in the load's 'early' block. Move LCA up above all predecessors
654 // which contain stores we have noted.
655 //
656 // The raised LCA block can be a home to such interfering stores,
657 // but its predecessors must not contain any such stores.
658 //
659 // The raised LCA will be a lower bound for placing the load,
660 // preventing the load from sinking past any block containing
661 // a store that may invalidate the memory state required by 'load'.
662 if (must_raise_LCA)
663 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs);
664 if (LCA == early) return LCA;
665
666 // Insert anti-dependence edges from 'load' to each store
667 // in the non-early LCA block.
668 // Mine the non_early_stores list for such stores.
669 if (LCA->raise_LCA_mark() == load_index) {
670 while (non_early_stores.size() > 0) {
671 Node* store = non_early_stores.pop();
672 Block* store_block = _bbs[store->_idx];
673 if (store_block == LCA) {
674 // add anti_dependence from store to load in its own block
675 assert(store != load->in(0), "dependence cycle found");
676 if (verify) {
677 assert(store->find_edge(load) != -1, "missing precedence edge");
678 } else {
679 store->add_prec(load);
680 }
681 } else {
682 assert(store_block->raise_LCA_mark() == load_index, "block was marked");
683 // Any other stores we found must be either inside the new LCA
684 // or else outside the original LCA. In the latter case, they
685 // did not interfere with any use of 'load'.
686 assert(LCA->dominates(store_block)
687 || !LCA_orig->dominates(store_block), "no stray stores");
688 }
689 }
690 }
691
692 // Return the highest block containing stores; any stores
693 // within that block have been given anti-dependence edges.
694 return LCA;
695 }
696
697 // This class is used to iterate backwards over the nodes in the graph.
698
699 class Node_Backward_Iterator {
700
701 private:
702 Node_Backward_Iterator();
703
704 public:
705 // Constructor for the iterator
706 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs);
707
708 // Postincrement operator to iterate over the nodes
709 Node *next();
710
711 private:
712 VectorSet &_visited;
713 Node_List &_stack;
714 Block_Array &_bbs;
715 };
716
717 // Constructor for the Node_Backward_Iterator
718 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs )
719 : _visited(visited), _stack(stack), _bbs(bbs) {
720 // The stack should contain exactly the root
721 stack.clear();
722 stack.push(root);
723
724 // Clear the visited bits
725 visited.Clear();
726 }
727
728 // Iterator for the Node_Backward_Iterator
729 Node *Node_Backward_Iterator::next() {
730
731 // If the _stack is empty, then just return NULL: finished.
732 if ( !_stack.size() )
733 return NULL;
734
735 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been
736 // made stateless, so I do not need to record the index 'i' on my _stack.
737 // Instead I visit all users each time, scanning for unvisited users.
738 // I visit unvisited not-anti-dependence users first, then anti-dependent
739 // children next.
740 Node *self = _stack.pop();
741
742 // I cycle here when I am entering a deeper level of recursion.
743 // The key variable 'self' was set prior to jumping here.
744 while( 1 ) {
745
746 _visited.set(self->_idx);
747
748 // Now schedule all uses as late as possible.
749 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx;
750 uint src_rpo = _bbs[src]->_rpo;
751
752 // Schedule all nodes in a post-order visit
753 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any
754
755 // Scan for unvisited nodes
756 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
757 // For all uses, schedule late
758 Node* n = self->fast_out(i); // Use
759
760 // Skip already visited children
761 if ( _visited.test(n->_idx) )
762 continue;
763
764 // do not traverse backward control edges
765 Node *use = n->is_Proj() ? n->in(0) : n;
766 uint use_rpo = _bbs[use->_idx]->_rpo;
767
768 if ( use_rpo < src_rpo )
769 continue;
770
771 // Phi nodes always precede uses in a basic block
772 if ( use_rpo == src_rpo && use->is_Phi() )
773 continue;
774
775 unvisited = n; // Found unvisited
776
777 // Check for possible-anti-dependent
778 if( !n->needs_anti_dependence_check() )
779 break; // Not visited, not anti-dep; schedule it NOW
780 }
781
782 // Did I find an unvisited not-anti-dependent Node?
783 if ( !unvisited )
784 break; // All done with children; post-visit 'self'
785
786 // Visit the unvisited Node. Contains the obvious push to
787 // indicate I'm entering a deeper level of recursion. I push the
788 // old state onto the _stack and set a new state and loop (recurse).
789 _stack.push(self);
790 self = unvisited;
791 } // End recursion loop
792
793 return self;
794 }
795
796 //------------------------------ComputeLatenciesBackwards----------------------
797 // Compute the latency of all the instructions.
798 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) {
799 #ifndef PRODUCT
800 if (trace_opto_pipelining())
801 tty->print("\n#---- ComputeLatenciesBackwards ----\n");
802 #endif
803
804 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
805 Node *n;
806
807 // Walk over all the nodes from last to first
808 while (n = iter.next()) {
809 // Set the latency for the definitions of this instruction
810 partial_latency_of_defs(n);
811 }
812 } // end ComputeLatenciesBackwards
813
814 //------------------------------partial_latency_of_defs------------------------
815 // Compute the latency impact of this node on all defs. This computes
816 // a number that increases as we approach the beginning of the routine.
817 void PhaseCFG::partial_latency_of_defs(Node *n) {
818 // Set the latency for this instruction
819 #ifndef PRODUCT
820 if (trace_opto_pipelining()) {
821 tty->print("# latency_to_inputs: node_latency[%d] = %d for node",
822 n->_idx, _node_latency.at_grow(n->_idx));
823 dump();
824 }
825 #endif
826
827 if (n->is_Proj())
828 n = n->in(0);
829
830 if (n->is_Root())
831 return;
832
833 uint nlen = n->len();
834 uint use_latency = _node_latency.at_grow(n->_idx);
835 uint use_pre_order = _bbs[n->_idx]->_pre_order;
836
837 for ( uint j=0; j<nlen; j++ ) {
838 Node *def = n->in(j);
839
840 if (!def || def == n)
841 continue;
842
843 // Walk backwards thru projections
844 if (def->is_Proj())
845 def = def->in(0);
846
847 #ifndef PRODUCT
848 if (trace_opto_pipelining()) {
849 tty->print("# in(%2d): ", j);
850 def->dump();
851 }
852 #endif
853
854 // If the defining block is not known, assume it is ok
855 Block *def_block = _bbs[def->_idx];
856 uint def_pre_order = def_block ? def_block->_pre_order : 0;
857
858 if ( (use_pre_order < def_pre_order) ||
859 (use_pre_order == def_pre_order && n->is_Phi()) )
860 continue;
861
862 uint delta_latency = n->latency(j);
863 uint current_latency = delta_latency + use_latency;
864
865 if (_node_latency.at_grow(def->_idx) < current_latency) {
866 _node_latency.at_put_grow(def->_idx, current_latency);
867 }
868
869 #ifndef PRODUCT
870 if (trace_opto_pipelining()) {
871 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d",
872 use_latency, j, delta_latency, current_latency, def->_idx,
873 _node_latency.at_grow(def->_idx));
874 }
875 #endif
876 }
877 }
878
879 //------------------------------latency_from_use-------------------------------
880 // Compute the latency of a specific use
881 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) {
882 // If self-reference, return no latency
883 if (use == n || use->is_Root())
884 return 0;
885
886 uint def_pre_order = _bbs[def->_idx]->_pre_order;
887 uint latency = 0;
888
889 // If the use is not a projection, then it is simple...
890 if (!use->is_Proj()) {
891 #ifndef PRODUCT
892 if (trace_opto_pipelining()) {
893 tty->print("# out(): ");
894 use->dump();
895 }
896 #endif
897
898 uint use_pre_order = _bbs[use->_idx]->_pre_order;
899
900 if (use_pre_order < def_pre_order)
901 return 0;
902
903 if (use_pre_order == def_pre_order && use->is_Phi())
904 return 0;
905
906 uint nlen = use->len();
907 uint nl = _node_latency.at_grow(use->_idx);
908
909 for ( uint j=0; j<nlen; j++ ) {
910 if (use->in(j) == n) {
911 // Change this if we want local latencies
912 uint ul = use->latency(j);
913 uint l = ul + nl;
914 if (latency < l) latency = l;
915 #ifndef PRODUCT
916 if (trace_opto_pipelining()) {
917 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d",
918 nl, j, ul, l, latency);
919 }
920 #endif
921 }
922 }
923 } else {
924 // This is a projection, just grab the latency of the use(s)
925 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) {
926 uint l = latency_from_use(use, def, use->fast_out(j));
927 if (latency < l) latency = l;
928 }
929 }
930
931 return latency;
932 }
933
934 //------------------------------latency_from_uses------------------------------
935 // Compute the latency of this instruction relative to all of it's uses.
936 // This computes a number that increases as we approach the beginning of the
937 // routine.
938 void PhaseCFG::latency_from_uses(Node *n) {
939 // Set the latency for this instruction
940 #ifndef PRODUCT
941 if (trace_opto_pipelining()) {
942 tty->print("# latency_from_outputs: node_latency[%d] = %d for node",
943 n->_idx, _node_latency.at_grow(n->_idx));
944 dump();
945 }
946 #endif
947 uint latency=0;
948 const Node *def = n->is_Proj() ? n->in(0): n;
949
950 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
951 uint l = latency_from_use(n, def, n->fast_out(i));
952
953 if (latency < l) latency = l;
954 }
955
956 _node_latency.at_put_grow(n->_idx, latency);
957 }
958
959 //------------------------------hoist_to_cheaper_block-------------------------
960 // Pick a block for node self, between early and LCA, that is a cheaper
961 // alternative to LCA.
962 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) {
963 const double delta = 1+PROB_UNLIKELY_MAG(4);
964 Block* least = LCA;
965 double least_freq = least->_freq;
966 uint target = _node_latency.at_grow(self->_idx);
967 uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx);
968 uint end_latency = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx);
969 bool in_latency = (target <= start_latency);
970 const Block* root_block = _bbs[_root->_idx];
971
972 // Turn off latency scheduling if scheduling is just plain off
973 if (!C->do_scheduling())
974 in_latency = true;
975
976 // Do not hoist (to cover latency) instructions which target a
977 // single register. Hoisting stretches the live range of the
978 // single register and may force spilling.
979 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
980 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty())
981 in_latency = true;
982
983 #ifndef PRODUCT
984 if (trace_opto_pipelining()) {
985 tty->print("# Find cheaper block for latency %d: ",
986 _node_latency.at_grow(self->_idx));
987 self->dump();
988 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
989 LCA->_pre_order,
990 LCA->_nodes[0]->_idx,
991 start_latency,
992 LCA->_nodes[LCA->end_idx()]->_idx,
993 end_latency,
994 least_freq);
995 }
996 #endif
997
998 // Walk up the dominator tree from LCA (Lowest common ancestor) to
999 // the earliest legal location. Capture the least execution frequency.
1000 while (LCA != early) {
1001 LCA = LCA->_idom; // Follow up the dominator tree
1002
1003 if (LCA == NULL) {
1004 // Bailout without retry
1005 C->record_method_not_compilable("late schedule failed: LCA == NULL");
1006 return least;
1007 }
1008
1009 // Don't hoist machine instructions to the root basic block
1010 if (mach && LCA == root_block)
1011 break;
1012
1013 uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx);
1014 uint end_idx = LCA->end_idx();
1015 uint end_lat = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx);
1016 double LCA_freq = LCA->_freq;
1017 #ifndef PRODUCT
1018 if (trace_opto_pipelining()) {
1019 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1020 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq);
1021 }
1022 #endif
1023 if (LCA_freq < least_freq || // Better Frequency
1024 ( !in_latency && // No block containing latency
1025 LCA_freq < least_freq * delta && // No worse frequency
1026 target >= end_lat && // within latency range
1027 !self->is_iteratively_computed() ) // But don't hoist IV increments
1028 // because they may end up above other uses of their phi forcing
1029 // their result register to be different from their input.
1030 ) {
1031 least = LCA; // Found cheaper block
1032 least_freq = LCA_freq;
1033 start_latency = start_lat;
1034 end_latency = end_lat;
1035 if (target <= start_lat)
1036 in_latency = true;
1037 }
1038 }
1039
1040 #ifndef PRODUCT
1041 if (trace_opto_pipelining()) {
1042 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g",
1043 least->_pre_order, start_latency, least_freq);
1044 }
1045 #endif
1046
1047 // See if the latency needs to be updated
1048 if (target < end_latency) {
1049 #ifndef PRODUCT
1050 if (trace_opto_pipelining()) {
1051 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency);
1052 }
1053 #endif
1054 _node_latency.at_put_grow(self->_idx, end_latency);
1055 partial_latency_of_defs(self);
1056 }
1057
1058 return least;
1059 }
1060
1061
1062 //------------------------------schedule_late-----------------------------------
1063 // Now schedule all codes as LATE as possible. This is the LCA in the
1064 // dominator tree of all USES of a value. Pick the block with the least
1065 // loop nesting depth that is lowest in the dominator tree.
1066 extern const char must_clone[];
1067 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) {
1068 #ifndef PRODUCT
1069 if (trace_opto_pipelining())
1070 tty->print("\n#---- schedule_late ----\n");
1071 #endif
1072
1073 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
1074 Node *self;
1075
1076 // Walk over all the nodes from last to first
1077 while (self = iter.next()) {
1078 Block* early = _bbs[self->_idx]; // Earliest legal placement
1079
1080 if (self->is_top()) {
1081 // Top node goes in bb #2 with other constants.
1082 // It must be special-cased, because it has no out edges.
1083 early->add_inst(self);
1084 continue;
1085 }
1086
1087 // No uses, just terminate
1088 if (self->outcnt() == 0) {
1089 assert(self->Opcode() == Op_MachProj, "sanity");
1090 continue; // Must be a dead machine projection
1091 }
1092
1093 // If node is pinned in the block, then no scheduling can be done.
1094 if( self->pinned() ) // Pinned in block?
1095 continue;
1096
1097 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
1098 if (mach) {
1099 switch (mach->ideal_Opcode()) {
1100 case Op_CreateEx:
1101 // Don't move exception creation
1102 early->add_inst(self);
1103 continue;
1104 break;
1105 case Op_CheckCastPP:
1106 // Don't move CheckCastPP nodes away from their input, if the input
1107 // is a rawptr (5071820).
1108 Node *def = self->in(1);
1109 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) {
1110 early->add_inst(self);
1111 continue;
1112 }
1113 break;
1114 }
1115 }
1116
1117 // Gather LCA of all uses
1118 Block *LCA = NULL;
1119 {
1120 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
1121 // For all uses, find LCA
1122 Node* use = self->fast_out(i);
1123 LCA = raise_LCA_above_use(LCA, use, self, _bbs);
1124 }
1125 } // (Hide defs of imax, i from rest of block.)
1126
1127 // Place temps in the block of their use. This isn't a
1128 // requirement for correctness but it reduces useless
1129 // interference between temps and other nodes.
1130 if (mach != NULL && mach->is_MachTemp()) {
1131 _bbs.map(self->_idx, LCA);
1132 LCA->add_inst(self);
1133 continue;
1134 }
1135
1136 // Check if 'self' could be anti-dependent on memory
1137 if (self->needs_anti_dependence_check()) {
1138 // Hoist LCA above possible-defs and insert anti-dependences to
1139 // defs in new LCA block.
1140 LCA = insert_anti_dependences(LCA, self);
1141 }
1142
1143 if (early->_dom_depth > LCA->_dom_depth) {
1144 // Somehow the LCA has moved above the earliest legal point.
1145 // (One way this can happen is via memory_early_block.)
1146 if (C->subsume_loads() == true && !C->failing()) {
1147 // Retry with subsume_loads == false
1148 // If this is the first failure, the sentinel string will "stick"
1149 // to the Compile object, and the C2Compiler will see it and retry.
1150 C->record_failure(C2Compiler::retry_no_subsuming_loads());
1151 } else {
1152 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth)
1153 C->record_method_not_compilable("late schedule failed: incorrect graph");
1154 }
1155 return;
1156 }
1157
1158 // If there is no opportunity to hoist, then we're done.
1159 bool try_to_hoist = (LCA != early);
1160
1161 // Must clone guys stay next to use; no hoisting allowed.
1162 // Also cannot hoist guys that alter memory or are otherwise not
1163 // allocatable (hoisting can make a value live longer, leading to
1164 // anti and output dependency problems which are normally resolved
1165 // by the register allocator giving everyone a different register).
1166 if (mach != NULL && must_clone[mach->ideal_Opcode()])
1167 try_to_hoist = false;
1168
1169 Block* late = NULL;
1170 if (try_to_hoist) {
1171 // Now find the block with the least execution frequency.
1172 // Start at the latest schedule and work up to the earliest schedule
1173 // in the dominator tree. Thus the Node will dominate all its uses.
1174 late = hoist_to_cheaper_block(LCA, early, self);
1175 } else {
1176 // Just use the LCA of the uses.
1177 late = LCA;
1178 }
1179
1180 // Put the node into target block
1181 schedule_node_into_block(self, late);
1182
1183 #ifdef ASSERT
1184 if (self->needs_anti_dependence_check()) {
1185 // since precedence edges are only inserted when we're sure they
1186 // are needed make sure that after placement in a block we don't
1187 // need any new precedence edges.
1188 verify_anti_dependences(late, self);
1189 }
1190 #endif
1191 } // Loop until all nodes have been visited
1192
1193 } // end ScheduleLate
1194
1195 //------------------------------GlobalCodeMotion-------------------------------
1196 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) {
1197 ResourceMark rm;
1198
1199 #ifndef PRODUCT
1200 if (trace_opto_pipelining()) {
1201 tty->print("\n---- Start GlobalCodeMotion ----\n");
1202 }
1203 #endif
1204
1205 // Initialize the bbs.map for things on the proj_list
1206 uint i;
1207 for( i=0; i < proj_list.size(); i++ )
1208 _bbs.map(proj_list[i]->_idx, NULL);
1209
1210 // Set the basic block for Nodes pinned into blocks
1211 Arena *a = Thread::current()->resource_area();
1212 VectorSet visited(a);
1213 schedule_pinned_nodes( visited );
1214
1215 // Find the earliest Block any instruction can be placed in. Some
1216 // instructions are pinned into Blocks. Unpinned instructions can
1217 // appear in last block in which all their inputs occur.
1218 visited.Clear();
1219 Node_List stack(a);
1220 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list
1221 if (!schedule_early(visited, stack)) {
1222 // Bailout without retry
1223 C->record_method_not_compilable("early schedule failed");
1224 return;
1225 }
1226
1227 // Build Def-Use edges.
1228 proj_list.push(_root); // Add real root as another root
1229 proj_list.pop();
1230
1231 // Compute the latency information (via backwards walk) for all the
1232 // instructions in the graph
1233 GrowableArray<uint> node_latency;
1234 _node_latency = node_latency;
1235
1236 if( C->do_scheduling() )
1237 ComputeLatenciesBackwards(visited, stack);
1238
1239 // Now schedule all codes as LATE as possible. This is the LCA in the
1240 // dominator tree of all USES of a value. Pick the block with the least
1241 // loop nesting depth that is lowest in the dominator tree.
1242 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() )
1243 schedule_late(visited, stack);
1244 if( C->failing() ) {
1245 // schedule_late fails only when graph is incorrect.
1246 assert(!VerifyGraphEdges, "verification should have failed");
1247 return;
1248 }
1249
1250 unique = C->unique();
1251
1252 #ifndef PRODUCT
1253 if (trace_opto_pipelining()) {
1254 tty->print("\n---- Detect implicit null checks ----\n");
1255 }
1256 #endif
1257
1258 // Detect implicit-null-check opportunities. Basically, find NULL checks
1259 // with suitable memory ops nearby. Use the memory op to do the NULL check.
1260 // I can generate a memory op if there is not one nearby.
1261 if (C->is_method_compilation()) {
1262 // Don't do it for natives, adapters, or runtime stubs
1263 int allowed_reasons = 0;
1264 // ...and don't do it when there have been too many traps, globally.
1265 for (int reason = (int)Deoptimization::Reason_none+1;
1266 reason < Compile::trapHistLength; reason++) {
1267 assert(reason < BitsPerInt, "recode bit map");
1268 if (!C->too_many_traps((Deoptimization::DeoptReason) reason))
1269 allowed_reasons |= nth_bit(reason);
1270 }
1271 // By reversing the loop direction we get a very minor gain on mpegaudio.
1272 // Feel free to revert to a forward loop for clarity.
1273 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) {
1274 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) {
1275 Node *proj = matcher._null_check_tests[i ];
1276 Node *val = matcher._null_check_tests[i+1];
1277 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons);
1278 // The implicit_null_check will only perform the transformation
1279 // if the null branch is truly uncommon, *and* it leads to an
1280 // uncommon trap. Combined with the too_many_traps guards
1281 // above, this prevents SEGV storms reported in 6366351,
1282 // by recompiling offending methods without this optimization.
1283 }
1284 }
1285
1286 #ifndef PRODUCT
1287 if (trace_opto_pipelining()) {
1288 tty->print("\n---- Start Local Scheduling ----\n");
1289 }
1290 #endif
1291
1292 // Schedule locally. Right now a simple topological sort.
1293 // Later, do a real latency aware scheduler.
1294 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique());
1295 memset( ready_cnt, -1, C->unique() * sizeof(int) );
1296 visited.Clear();
1297 for (i = 0; i < _num_blocks; i++) {
1298 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) {
1299 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
1300 C->record_method_not_compilable("local schedule failed");
1301 }
1302 return;
1303 }
1304 }
1305
1306 // If we inserted any instructions between a Call and his CatchNode,
1307 // clone the instructions on all paths below the Catch.
1308 for( i=0; i < _num_blocks; i++ )
1309 _blocks[i]->call_catch_cleanup(_bbs);
1310
1311 #ifndef PRODUCT
1312 if (trace_opto_pipelining()) {
1313 tty->print("\n---- After GlobalCodeMotion ----\n");
1314 for (uint i = 0; i < _num_blocks; i++) {
1315 _blocks[i]->dump();
1316 }
1317 }
1318 #endif
1319 }
1320
1321
1322 //------------------------------Estimate_Block_Frequency-----------------------
1323 // Estimate block frequencies based on IfNode probabilities.
1324 void PhaseCFG::Estimate_Block_Frequency() {
1325
1326 // Force conditional branches leading to uncommon traps to be unlikely,
1327 // not because we get to the uncommon_trap with less relative frequency,
1328 // but because an uncommon_trap typically causes a deopt, so we only get
1329 // there once.
1330 if (C->do_freq_based_layout()) {
1331 Block_List worklist;
1332 Block* root_blk = _blocks[0];
1333 for (uint i = 1; i < root_blk->num_preds(); i++) {
1334 Block *pb = _bbs[root_blk->pred(i)->_idx];
1335 if (pb->has_uncommon_code()) {
1336 worklist.push(pb);
1337 }
1338 }
1339 while (worklist.size() > 0) {
1340 Block* uct = worklist.pop();
1341 if (uct == _broot) continue;
1342 for (uint i = 1; i < uct->num_preds(); i++) {
1343 Block *pb = _bbs[uct->pred(i)->_idx];
1344 if (pb->_num_succs == 1) {
1345 worklist.push(pb);
1346 } else if (pb->num_fall_throughs() == 2) {
1347 pb->update_uncommon_branch(uct);
1348 }
1349 }
1350 }
1351 }
1352
1353 // Create the loop tree and calculate loop depth.
1354 _root_loop = create_loop_tree();
1355 _root_loop->compute_loop_depth(0);
1356
1357 // Compute block frequency of each block, relative to a single loop entry.
1358 _root_loop->compute_freq();
1359
1360 // Adjust all frequencies to be relative to a single method entry
1361 _root_loop->_freq = 1.0;
1362 _root_loop->scale_freq();
1363
1364 // force paths ending at uncommon traps to be infrequent
1365 if (!C->do_freq_based_layout()) {
1366 Block_List worklist;
1367 Block* root_blk = _blocks[0];
1368 for (uint i = 1; i < root_blk->num_preds(); i++) {
1369 Block *pb = _bbs[root_blk->pred(i)->_idx];
1370 if (pb->has_uncommon_code()) {
1371 worklist.push(pb);
1372 }
1373 }
1374 while (worklist.size() > 0) {
1375 Block* uct = worklist.pop();
1376 uct->_freq = PROB_MIN;
1377 for (uint i = 1; i < uct->num_preds(); i++) {
1378 Block *pb = _bbs[uct->pred(i)->_idx];
1379 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) {
1380 worklist.push(pb);
1381 }
1382 }
1383 }
1384 }
1385
1386 #ifdef ASSERT
1387 for (uint i = 0; i < _num_blocks; i++ ) {
1388 Block *b = _blocks[i];
1389 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requiers meaningful block frequency");
1390 }
1391 #endif
1392
1393 #ifndef PRODUCT
1394 if (PrintCFGBlockFreq) {
1395 tty->print_cr("CFG Block Frequencies");
1396 _root_loop->dump_tree();
1397 if (Verbose) {
1398 tty->print_cr("PhaseCFG dump");
1399 dump();
1400 tty->print_cr("Node dump");
1401 _root->dump(99999);
1402 }
1403 }
1404 #endif
1405 }
1406
1407 //----------------------------create_loop_tree--------------------------------
1408 // Create a loop tree from the CFG
1409 CFGLoop* PhaseCFG::create_loop_tree() {
1410
1411 #ifdef ASSERT
1412 assert( _blocks[0] == _broot, "" );
1413 for (uint i = 0; i < _num_blocks; i++ ) {
1414 Block *b = _blocks[i];
1415 // Check that _loop field are clear...we could clear them if not.
1416 assert(b->_loop == NULL, "clear _loop expected");
1417 // Sanity check that the RPO numbering is reflected in the _blocks array.
1418 // It doesn't have to be for the loop tree to be built, but if it is not,
1419 // then the blocks have been reordered since dom graph building...which
1420 // may question the RPO numbering
1421 assert(b->_rpo == i, "unexpected reverse post order number");
1422 }
1423 #endif
1424
1425 int idct = 0;
1426 CFGLoop* root_loop = new CFGLoop(idct++);
1427
1428 Block_List worklist;
1429
1430 // Assign blocks to loops
1431 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block
1432 Block *b = _blocks[i];
1433
1434 if (b->head()->is_Loop()) {
1435 Block* loop_head = b;
1436 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1437 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl);
1438 Block* tail = _bbs[tail_n->_idx];
1439
1440 // Defensively filter out Loop nodes for non-single-entry loops.
1441 // For all reasonable loops, the head occurs before the tail in RPO.
1442 if (i <= tail->_rpo) {
1443
1444 // The tail and (recursive) predecessors of the tail
1445 // are made members of a new loop.
1446
1447 assert(worklist.size() == 0, "nonempty worklist");
1448 CFGLoop* nloop = new CFGLoop(idct++);
1449 assert(loop_head->_loop == NULL, "just checking");
1450 loop_head->_loop = nloop;
1451 // Add to nloop so push_pred() will skip over inner loops
1452 nloop->add_member(loop_head);
1453 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs);
1454
1455 while (worklist.size() > 0) {
1456 Block* member = worklist.pop();
1457 if (member != loop_head) {
1458 for (uint j = 1; j < member->num_preds(); j++) {
1459 nloop->push_pred(member, j, worklist, _bbs);
1460 }
1461 }
1462 }
1463 }
1464 }
1465 }
1466
1467 // Create a member list for each loop consisting
1468 // of both blocks and (immediate child) loops.
1469 for (uint i = 0; i < _num_blocks; i++) {
1470 Block *b = _blocks[i];
1471 CFGLoop* lp = b->_loop;
1472 if (lp == NULL) {
1473 // Not assigned to a loop. Add it to the method's pseudo loop.
1474 b->_loop = root_loop;
1475 lp = root_loop;
1476 }
1477 if (lp == root_loop || b != lp->head()) { // loop heads are already members
1478 lp->add_member(b);
1479 }
1480 if (lp != root_loop) {
1481 if (lp->parent() == NULL) {
1482 // Not a nested loop. Make it a child of the method's pseudo loop.
1483 root_loop->add_nested_loop(lp);
1484 }
1485 if (b == lp->head()) {
1486 // Add nested loop to member list of parent loop.
1487 lp->parent()->add_member(lp);
1488 }
1489 }
1490 }
1491
1492 return root_loop;
1493 }
1494
1495 //------------------------------push_pred--------------------------------------
1496 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) {
1497 Node* pred_n = blk->pred(i);
1498 Block* pred = node_to_blk[pred_n->_idx];
1499 CFGLoop *pred_loop = pred->_loop;
1500 if (pred_loop == NULL) {
1501 // Filter out blocks for non-single-entry loops.
1502 // For all reasonable loops, the head occurs before the tail in RPO.
1503 if (pred->_rpo > head()->_rpo) {
1504 pred->_loop = this;
1505 worklist.push(pred);
1506 }
1507 } else if (pred_loop != this) {
1508 // Nested loop.
1509 while (pred_loop->_parent != NULL && pred_loop->_parent != this) {
1510 pred_loop = pred_loop->_parent;
1511 }
1512 // Make pred's loop be a child
1513 if (pred_loop->_parent == NULL) {
1514 add_nested_loop(pred_loop);
1515 // Continue with loop entry predecessor.
1516 Block* pred_head = pred_loop->head();
1517 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1518 assert(pred_head != head(), "loop head in only one loop");
1519 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk);
1520 } else {
1521 assert(pred_loop->_parent == this && _parent == NULL, "just checking");
1522 }
1523 }
1524 }
1525
1526 //------------------------------add_nested_loop--------------------------------
1527 // Make cl a child of the current loop in the loop tree.
1528 void CFGLoop::add_nested_loop(CFGLoop* cl) {
1529 assert(_parent == NULL, "no parent yet");
1530 assert(cl != this, "not my own parent");
1531 cl->_parent = this;
1532 CFGLoop* ch = _child;
1533 if (ch == NULL) {
1534 _child = cl;
1535 } else {
1536 while (ch->_sibling != NULL) { ch = ch->_sibling; }
1537 ch->_sibling = cl;
1538 }
1539 }
1540
1541 //------------------------------compute_loop_depth-----------------------------
1542 // Store the loop depth in each CFGLoop object.
1543 // Recursively walk the children to do the same for them.
1544 void CFGLoop::compute_loop_depth(int depth) {
1545 _depth = depth;
1546 CFGLoop* ch = _child;
1547 while (ch != NULL) {
1548 ch->compute_loop_depth(depth + 1);
1549 ch = ch->_sibling;
1550 }
1551 }
1552
1553 //------------------------------compute_freq-----------------------------------
1554 // Compute the frequency of each block and loop, relative to a single entry
1555 // into the dominating loop head.
1556 void CFGLoop::compute_freq() {
1557 // Bottom up traversal of loop tree (visit inner loops first.)
1558 // Set loop head frequency to 1.0, then transitively
1559 // compute frequency for all successors in the loop,
1560 // as well as for each exit edge. Inner loops are
1561 // treated as single blocks with loop exit targets
1562 // as the successor blocks.
1563
1564 // Nested loops first
1565 CFGLoop* ch = _child;
1566 while (ch != NULL) {
1567 ch->compute_freq();
1568 ch = ch->_sibling;
1569 }
1570 assert (_members.length() > 0, "no empty loops");
1571 Block* hd = head();
1572 hd->_freq = 1.0f;
1573 for (int i = 0; i < _members.length(); i++) {
1574 CFGElement* s = _members.at(i);
1575 float freq = s->_freq;
1576 if (s->is_block()) {
1577 Block* b = s->as_Block();
1578 for (uint j = 0; j < b->_num_succs; j++) {
1579 Block* sb = b->_succs[j];
1580 update_succ_freq(sb, freq * b->succ_prob(j));
1581 }
1582 } else {
1583 CFGLoop* lp = s->as_CFGLoop();
1584 assert(lp->_parent == this, "immediate child");
1585 for (int k = 0; k < lp->_exits.length(); k++) {
1586 Block* eb = lp->_exits.at(k).get_target();
1587 float prob = lp->_exits.at(k).get_prob();
1588 update_succ_freq(eb, freq * prob);
1589 }
1590 }
1591 }
1592
1593 // For all loops other than the outer, "method" loop,
1594 // sum and normalize the exit probability. The "method" loop
1595 // should keep the initial exit probability of 1, so that
1596 // inner blocks do not get erroneously scaled.
1597 if (_depth != 0) {
1598 // Total the exit probabilities for this loop.
1599 float exits_sum = 0.0f;
1600 for (int i = 0; i < _exits.length(); i++) {
1601 exits_sum += _exits.at(i).get_prob();
1602 }
1603
1604 // Normalize the exit probabilities. Until now, the
1605 // probabilities estimate the possibility of exit per
1606 // a single loop iteration; afterward, they estimate
1607 // the probability of exit per loop entry.
1608 for (int i = 0; i < _exits.length(); i++) {
1609 Block* et = _exits.at(i).get_target();
1610 float new_prob = 0.0f;
1611 if (_exits.at(i).get_prob() > 0.0f) {
1612 new_prob = _exits.at(i).get_prob() / exits_sum;
1613 }
1614 BlockProbPair bpp(et, new_prob);
1615 _exits.at_put(i, bpp);
1616 }
1617
1618 // Save the total, but guard against unreasonable probability,
1619 // as the value is used to estimate the loop trip count.
1620 // An infinite trip count would blur relative block
1621 // frequencies.
1622 if (exits_sum > 1.0f) exits_sum = 1.0;
1623 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN;
1624 _exit_prob = exits_sum;
1625 }
1626 }
1627
1628 //------------------------------succ_prob-------------------------------------
1629 // Determine the probability of reaching successor 'i' from the receiver block.
1630 float Block::succ_prob(uint i) {
1631 int eidx = end_idx();
1632 Node *n = _nodes[eidx]; // Get ending Node
1633
1634 int op = n->Opcode();
1635 if (n->is_Mach()) {
1636 if (n->is_MachNullCheck()) {
1637 // Can only reach here if called after lcm. The original Op_If is gone,
1638 // so we attempt to infer the probability from one or both of the
1639 // successor blocks.
1640 assert(_num_succs == 2, "expecting 2 successors of a null check");
1641 // If either successor has only one predecessor, then the
1642 // probabiltity estimate can be derived using the
1643 // relative frequency of the successor and this block.
1644 if (_succs[i]->num_preds() == 2) {
1645 return _succs[i]->_freq / _freq;
1646 } else if (_succs[1-i]->num_preds() == 2) {
1647 return 1 - (_succs[1-i]->_freq / _freq);
1648 } else {
1649 // Estimate using both successor frequencies
1650 float freq = _succs[i]->_freq;
1651 return freq / (freq + _succs[1-i]->_freq);
1652 }
1653 }
1654 op = n->as_Mach()->ideal_Opcode();
1655 }
1656
1657
1658 // Switch on branch type
1659 switch( op ) {
1660 case Op_CountedLoopEnd:
1661 case Op_If: {
1662 assert (i < 2, "just checking");
1663 // Conditionals pass on only part of their frequency
1664 float prob = n->as_MachIf()->_prob;
1665 assert(prob >= 0.0 && prob <= 1.0, "out of range probability");
1666 // If succ[i] is the FALSE branch, invert path info
1667 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) {
1668 return 1.0f - prob; // not taken
1669 } else {
1670 return prob; // taken
1671 }
1672 }
1673
1674 case Op_Jump:
1675 // Divide the frequency between all successors evenly
1676 return 1.0f/_num_succs;
1677
1678 case Op_Catch: {
1679 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1680 if (ci->_con == CatchProjNode::fall_through_index) {
1681 // Fall-thru path gets the lion's share.
1682 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs;
1683 } else {
1684 // Presume exceptional paths are equally unlikely
1685 return PROB_UNLIKELY_MAG(5);
1686 }
1687 }
1688
1689 case Op_Root:
1690 case Op_Goto:
1691 // Pass frequency straight thru to target
1692 return 1.0f;
1693
1694 case Op_NeverBranch:
1695 return 0.0f;
1696
1697 case Op_TailCall:
1698 case Op_TailJump:
1699 case Op_Return:
1700 case Op_Halt:
1701 case Op_Rethrow:
1702 // Do not push out freq to root block
1703 return 0.0f;
1704
1705 default:
1706 ShouldNotReachHere();
1707 }
1708
1709 return 0.0f;
1710 }
1711
1712 //------------------------------num_fall_throughs-----------------------------
1713 // Return the number of fall-through candidates for a block
1714 int Block::num_fall_throughs() {
1715 int eidx = end_idx();
1716 Node *n = _nodes[eidx]; // Get ending Node
1717
1718 int op = n->Opcode();
1719 if (n->is_Mach()) {
1720 if (n->is_MachNullCheck()) {
1721 // In theory, either side can fall-thru, for simplicity sake,
1722 // let's say only the false branch can now.
1723 return 1;
1724 }
1725 op = n->as_Mach()->ideal_Opcode();
1726 }
1727
1728 // Switch on branch type
1729 switch( op ) {
1730 case Op_CountedLoopEnd:
1731 case Op_If:
1732 return 2;
1733
1734 case Op_Root:
1735 case Op_Goto:
1736 return 1;
1737
1738 case Op_Catch: {
1739 for (uint i = 0; i < _num_succs; i++) {
1740 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1741 if (ci->_con == CatchProjNode::fall_through_index) {
1742 return 1;
1743 }
1744 }
1745 return 0;
1746 }
1747
1748 case Op_Jump:
1749 case Op_NeverBranch:
1750 case Op_TailCall:
1751 case Op_TailJump:
1752 case Op_Return:
1753 case Op_Halt:
1754 case Op_Rethrow:
1755 return 0;
1756
1757 default:
1758 ShouldNotReachHere();
1759 }
1760
1761 return 0;
1762 }
1763
1764 //------------------------------succ_fall_through-----------------------------
1765 // Return true if a specific successor could be fall-through target.
1766 bool Block::succ_fall_through(uint i) {
1767 int eidx = end_idx();
1768 Node *n = _nodes[eidx]; // Get ending Node
1769
1770 int op = n->Opcode();
1771 if (n->is_Mach()) {
1772 if (n->is_MachNullCheck()) {
1773 // In theory, either side can fall-thru, for simplicity sake,
1774 // let's say only the false branch can now.
1775 return _nodes[i + eidx + 1]->Opcode() == Op_IfFalse;
1776 }
1777 op = n->as_Mach()->ideal_Opcode();
1778 }
1779
1780 // Switch on branch type
1781 switch( op ) {
1782 case Op_CountedLoopEnd:
1783 case Op_If:
1784 case Op_Root:
1785 case Op_Goto:
1786 return true;
1787
1788 case Op_Catch: {
1789 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1790 return ci->_con == CatchProjNode::fall_through_index;
1791 }
1792
1793 case Op_Jump:
1794 case Op_NeverBranch:
1795 case Op_TailCall:
1796 case Op_TailJump:
1797 case Op_Return:
1798 case Op_Halt:
1799 case Op_Rethrow:
1800 return false;
1801
1802 default:
1803 ShouldNotReachHere();
1804 }
1805
1806 return false;
1807 }
1808
1809 //------------------------------update_uncommon_branch------------------------
1810 // Update the probability of a two-branch to be uncommon
1811 void Block::update_uncommon_branch(Block* ub) {
1812 int eidx = end_idx();
1813 Node *n = _nodes[eidx]; // Get ending Node
1814
1815 int op = n->as_Mach()->ideal_Opcode();
1816
1817 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If");
1818 assert(num_fall_throughs() == 2, "must be a two way branch block");
1819
1820 // Which successor is ub?
1821 uint s;
1822 for (s = 0; s <_num_succs; s++) {
1823 if (_succs[s] == ub) break;
1824 }
1825 assert(s < 2, "uncommon successor must be found");
1826
1827 // If ub is the true path, make the proability small, else
1828 // ub is the false path, and make the probability large
1829 bool invert = (_nodes[s + eidx + 1]->Opcode() == Op_IfFalse);
1830
1831 // Get existing probability
1832 float p = n->as_MachIf()->_prob;
1833
1834 if (invert) p = 1.0 - p;
1835 if (p > PROB_MIN) {
1836 p = PROB_MIN;
1837 }
1838 if (invert) p = 1.0 - p;
1839
1840 n->as_MachIf()->_prob = p;
1841 }
1842
1843 //------------------------------update_succ_freq-------------------------------
1844 // Update the appropriate frequency associated with block 'b', a succesor of
1845 // a block in this loop.
1846 void CFGLoop::update_succ_freq(Block* b, float freq) {
1847 if (b->_loop == this) {
1848 if (b == head()) {
1849 // back branch within the loop
1850 // Do nothing now, the loop carried frequency will be
1851 // adjust later in scale_freq().
1852 } else {
1853 // simple branch within the loop
1854 b->_freq += freq;
1855 }
1856 } else if (!in_loop_nest(b)) {
1857 // branch is exit from this loop
1858 BlockProbPair bpp(b, freq);
1859 _exits.append(bpp);
1860 } else {
1861 // branch into nested loop
1862 CFGLoop* ch = b->_loop;
1863 ch->_freq += freq;
1864 }
1865 }
1866
1867 //------------------------------in_loop_nest-----------------------------------
1868 // Determine if block b is in the receiver's loop nest.
1869 bool CFGLoop::in_loop_nest(Block* b) {
1870 int depth = _depth;
1871 CFGLoop* b_loop = b->_loop;
1872 int b_depth = b_loop->_depth;
1873 if (depth == b_depth) {
1874 return true;
1875 }
1876 while (b_depth > depth) {
1877 b_loop = b_loop->_parent;
1878 b_depth = b_loop->_depth;
1879 }
1880 return b_loop == this;
1881 }
1882
1883 //------------------------------scale_freq-------------------------------------
1884 // Scale frequency of loops and blocks by trip counts from outer loops
1885 // Do a top down traversal of loop tree (visit outer loops first.)
1886 void CFGLoop::scale_freq() {
1887 float loop_freq = _freq * trip_count();
1888 for (int i = 0; i < _members.length(); i++) {
1889 CFGElement* s = _members.at(i);
1890 float block_freq = s->_freq * loop_freq;
1891 if (block_freq < MIN_BLOCK_FREQUENCY) block_freq = MIN_BLOCK_FREQUENCY;
1892 s->_freq = block_freq;
1893 }
1894 CFGLoop* ch = _child;
1895 while (ch != NULL) {
1896 ch->scale_freq();
1897 ch = ch->_sibling;
1898 }
1899 }
1900
1901 #ifndef PRODUCT
1902 //------------------------------dump_tree--------------------------------------
1903 void CFGLoop::dump_tree() const {
1904 dump();
1905 if (_child != NULL) _child->dump_tree();
1906 if (_sibling != NULL) _sibling->dump_tree();
1907 }
1908
1909 //------------------------------dump-------------------------------------------
1910 void CFGLoop::dump() const {
1911 for (int i = 0; i < _depth; i++) tty->print(" ");
1912 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n",
1913 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq);
1914 for (int i = 0; i < _depth; i++) tty->print(" ");
1915 tty->print(" members:", _id);
1916 int k = 0;
1917 for (int i = 0; i < _members.length(); i++) {
1918 if (k++ >= 6) {
1919 tty->print("\n ");
1920 for (int j = 0; j < _depth+1; j++) tty->print(" ");
1921 k = 0;
1922 }
1923 CFGElement *s = _members.at(i);
1924 if (s->is_block()) {
1925 Block *b = s->as_Block();
1926 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq);
1927 } else {
1928 CFGLoop* lp = s->as_CFGLoop();
1929 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq);
1930 }
1931 }
1932 tty->print("\n");
1933 for (int i = 0; i < _depth; i++) tty->print(" ");
1934 tty->print(" exits: ");
1935 k = 0;
1936 for (int i = 0; i < _exits.length(); i++) {
1937 if (k++ >= 7) {
1938 tty->print("\n ");
1939 for (int j = 0; j < _depth+1; j++) tty->print(" ");
1940 k = 0;
1941 }
1942 Block *blk = _exits.at(i).get_target();
1943 float prob = _exits.at(i).get_prob();
1944 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100));
1945 }
1946 tty->print("\n");
1947 }
1948 #endif