1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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23 */
24
25 #include "libadt/vectset.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "opto/block.hpp"
29 #include "opto/c2compiler.hpp"
30 #include "opto/callnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/chaitin.hpp"
33 #include "opto/machnode.hpp"
34 #include "opto/opcodes.hpp"
35 #include "opto/phaseX.hpp"
36 #include "opto/rootnode.hpp"
37 #include "opto/runtime.hpp"
38 #include "runtime/deoptimization.hpp"
39
40 // Portions of code courtesy of Clifford Click
41
42 // Optimization - Graph Style
43
44 // To avoid float value underflow
45 #define MIN_BLOCK_FREQUENCY 1.e-35f
46
47 //----------------------------schedule_node_into_block-------------------------
48 // Insert node n into block b. Look for projections of n and make sure they
49 // are in b also.
50 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) {
51 // Set basic block of n, Add n to b,
52 map_node_to_block(n, b);
53 b->add_inst(n);
54
55 // After Matching, nearly any old Node may have projections trailing it.
56 // These are usually machine-dependent flags. In any case, they might
57 // float to another block below this one. Move them up.
58 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
59 Node* use = n->fast_out(i);
60 if (use->is_Proj()) {
61 Block* buse = get_block_for_node(use);
62 if (buse != b) { // In wrong block?
63 if (buse != nullptr) {
64 buse->find_remove(use); // Remove from wrong block
65 }
66 map_node_to_block(use, b);
67 b->add_inst(use);
68 }
69 }
70 }
71 }
72
73 //----------------------------replace_block_proj_ctrl-------------------------
74 // Nodes that have is_block_proj() nodes as their control need to use
75 // the appropriate Region for their actual block as their control since
76 // the projection will be in a predecessor block.
77 void PhaseCFG::replace_block_proj_ctrl( Node *n ) {
78 const Node *in0 = n->in(0);
79 assert(in0 != nullptr, "Only control-dependent");
80 const Node *p = in0->is_block_proj();
81 if (p != nullptr && p != n) { // Control from a block projection?
82 assert(!n->pinned() || n->is_MachConstantBase(), "only pinned MachConstantBase node is expected here");
83 // Find trailing Region
84 Block *pb = get_block_for_node(in0); // Block-projection already has basic block
85 uint j = 0;
86 if (pb->_num_succs != 1) { // More then 1 successor?
87 // Search for successor
88 uint max = pb->number_of_nodes();
89 assert( max > 1, "" );
90 uint start = max - pb->_num_succs;
91 // Find which output path belongs to projection
92 for (j = start; j < max; j++) {
93 if( pb->get_node(j) == in0 )
94 break;
95 }
96 assert( j < max, "must find" );
97 // Change control to match head of successor basic block
98 j -= start;
99 }
100 n->set_req(0, pb->_succs[j]->head());
101 }
102 }
103
104 bool PhaseCFG::is_dominator(Node* dom_node, Node* node) {
105 assert(is_CFG(node) && is_CFG(dom_node), "node and dom_node must be CFG nodes");
106 if (dom_node == node) {
107 return true;
108 }
109 Block* d = find_block_for_node(dom_node);
110 Block* n = find_block_for_node(node);
111 assert(n != nullptr && d != nullptr, "blocks must exist");
112
113 if (d == n) {
114 if (dom_node->is_block_start()) {
115 return true;
116 }
117 if (node->is_block_start()) {
118 return false;
119 }
120 if (dom_node->is_block_proj()) {
121 return false;
122 }
123 if (node->is_block_proj()) {
124 return true;
125 }
126
127 assert(is_control_proj_or_safepoint(node), "node must be control projection or safepoint");
128 assert(is_control_proj_or_safepoint(dom_node), "dom_node must be control projection or safepoint");
129
130 // Neither 'node' nor 'dom_node' is a block start or block projection.
131 // Check if 'dom_node' is above 'node' in the control graph.
132 if (is_dominating_control(dom_node, node)) {
133 return true;
134 }
135
136 #ifdef ASSERT
137 // If 'dom_node' does not dominate 'node' then 'node' has to dominate 'dom_node'
138 if (!is_dominating_control(node, dom_node)) {
139 node->dump();
140 dom_node->dump();
141 assert(false, "neither dom_node nor node dominates the other");
142 }
143 #endif
144
145 return false;
146 }
147 return d->dom_lca(n) == d;
148 }
149
150 bool PhaseCFG::is_CFG(Node* n) {
151 return n->is_block_proj() || n->is_block_start() || is_control_proj_or_safepoint(n);
152 }
153
154 bool PhaseCFG::is_control_proj_or_safepoint(Node* n) const {
155 bool result = n->is_ReachabilityFence() ||
156 (n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_SafePoint) ||
157 (n->is_Proj() && n->as_Proj()->bottom_type() == Type::CONTROL);
158 assert(!n->is_Proj() ||
159 n->as_Proj()->bottom_type() != Type::CONTROL ||
160 n->as_Proj()->_con == 0, "If control projection, it must be projection 0");
161 return result;
162 }
163
164 Block* PhaseCFG::find_block_for_node(Node* n) const {
165 if (n->is_block_start() || n->is_block_proj()) {
166 return get_block_for_node(n);
167 } else {
168 // Walk the control graph up if 'n' is not a block start nor a block projection. In this case 'n' must be
169 // an unmatched control projection or a not yet matched safepoint precedence edge in the middle of a block.
170 assert(is_control_proj_or_safepoint(n), "must be control projection or safepoint");
171 Node* ctrl = n->in(0);
172 while (!ctrl->is_block_start()) {
173 ctrl = ctrl->in(0);
174 }
175 return get_block_for_node(ctrl);
176 }
177 }
178
179 // Walk up the control graph from 'n' and check if 'dom_ctrl' is found.
180 bool PhaseCFG::is_dominating_control(Node* dom_ctrl, Node* n) {
181 Node* ctrl = n->in(0);
182 while (!ctrl->is_block_start()) {
183 if (ctrl == dom_ctrl) {
184 return true;
185 }
186 ctrl = ctrl->in(0);
187 }
188 return false;
189 }
190
191
192 //------------------------------schedule_pinned_nodes--------------------------
193 // Set the basic block for Nodes pinned into blocks
194 void PhaseCFG::schedule_pinned_nodes(VectorSet &visited) {
195 // Allocate node stack of size C->live_nodes()+8 to avoid frequent realloc
196 GrowableArray <Node*> spstack(C->live_nodes() + 8);
197 spstack.push(_root);
198 while (spstack.is_nonempty()) {
199 Node* node = spstack.pop();
200 if (!visited.test_set(node->_idx)) { // Test node and flag it as visited
201 if (node->pinned() && !has_block(node)) { // Pinned? Nail it down!
202 assert(node->in(0), "pinned Node must have Control");
203 // Before setting block replace block_proj control edge
204 replace_block_proj_ctrl(node);
205 Node* input = node->in(0);
206 while (!input->is_block_start()) {
207 input = input->in(0);
208 }
209 Block* block = get_block_for_node(input); // Basic block of controlling input
210 schedule_node_into_block(node, block);
211 }
212
213 // If the node has precedence edges (added when CastPP nodes are
214 // removed in final_graph_reshaping), fix the control of the
215 // node to cover the precedence edges and remove the
216 // dependencies.
217 Node* n = nullptr;
218 for (uint i = node->len()-1; i >= node->req(); i--) {
219 Node* m = node->in(i);
220 if (m == nullptr) continue;
221 assert(is_CFG(m), "must be a CFG node");
222 node->rm_prec(i);
223 if (n == nullptr) {
224 n = m;
225 } else {
226 assert(is_dominator(n, m) || is_dominator(m, n), "one must dominate the other");
227 n = is_dominator(n, m) ? m : n;
228 }
229 }
230 if (n != nullptr) {
231 assert(node->in(0), "control should have been set");
232 assert(is_dominator(n, node->in(0)) || is_dominator(node->in(0), n), "one must dominate the other");
233 if (!is_dominator(n, node->in(0))) {
234 node->set_req(0, n);
235 }
236 }
237
238 // process all inputs that are non null
239 for (int i = node->len()-1; i >= 0; --i) {
240 if (node->in(i) != nullptr) {
241 spstack.push(node->in(i));
242 }
243 }
244 }
245 }
246 }
247
248 // Assert that new input b2 is dominated by all previous inputs.
249 // Check this by by seeing that it is dominated by b1, the deepest
250 // input observed until b2.
251 static void assert_dom(Block* b1, Block* b2, Node* n, const PhaseCFG* cfg) {
252 if (b1 == nullptr) return;
253 assert(b1->_dom_depth < b2->_dom_depth, "sanity");
254 Block* tmp = b2;
255 while (tmp != b1 && tmp != nullptr) {
256 tmp = tmp->_idom;
257 }
258 if (tmp != b1) {
259 #ifdef ASSERT
260 // Detected an unschedulable graph. Print some nice stuff and die.
261 tty->print_cr("!!! Unschedulable graph !!!");
262 for (uint j=0; j<n->len(); j++) { // For all inputs
263 Node* inn = n->in(j); // Get input
264 if (inn == nullptr) continue; // Ignore null, missing inputs
265 Block* inb = cfg->get_block_for_node(inn);
266 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order,
267 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth);
268 inn->dump();
269 }
270 tty->print("Failing node: ");
271 n->dump();
272 assert(false, "unschedulable graph");
273 #endif
274 cfg->C->record_failure("unschedulable graph");
275 }
276 }
277
278 static Block* find_deepest_input(Node* n, const PhaseCFG* cfg) {
279 // Find the last input dominated by all other inputs.
280 Block* deepb = nullptr; // Deepest block so far
281 int deepb_dom_depth = 0;
282 for (uint k = 0; k < n->len(); k++) { // For all inputs
283 Node* inn = n->in(k); // Get input
284 if (inn == nullptr) continue; // Ignore null, missing inputs
285 Block* inb = cfg->get_block_for_node(inn);
286 assert(inb != nullptr, "must already have scheduled this input");
287 if (deepb_dom_depth < (int) inb->_dom_depth) {
288 // The new inb must be dominated by the previous deepb.
289 // The various inputs must be linearly ordered in the dom
290 // tree, or else there will not be a unique deepest block.
291 assert_dom(deepb, inb, n, cfg);
292 if (cfg->C->failing()) {
293 return nullptr;
294 }
295 deepb = inb; // Save deepest block
296 deepb_dom_depth = deepb->_dom_depth;
297 }
298 }
299 assert(deepb != nullptr, "must be at least one input to n");
300 return deepb;
301 }
302
303
304 //------------------------------schedule_early---------------------------------
305 // Find the earliest Block any instruction can be placed in. Some instructions
306 // are pinned into Blocks. Unpinned instructions can appear in last block in
307 // which all their inputs occur.
308 bool PhaseCFG::schedule_early(VectorSet &visited, Node_Stack &roots) {
309 // Allocate stack with enough space to avoid frequent realloc
310 Node_Stack nstack(roots.size() + 8);
311 // _root will be processed among C->top() inputs
312 roots.push(C->top(), 0);
313 visited.set(C->top()->_idx);
314
315 while (roots.size() != 0) {
316 // Use local variables nstack_top_n & nstack_top_i to cache values
317 // on stack's top.
318 Node* parent_node = roots.node();
319 uint input_index = 0;
320 roots.pop();
321
322 while (true) {
323 if (input_index == 0) {
324 // Fixup some control. Constants without control get attached
325 // to root and nodes that use is_block_proj() nodes should be attached
326 // to the region that starts their block.
327 const Node* control_input = parent_node->in(0);
328 if (control_input != nullptr) {
329 replace_block_proj_ctrl(parent_node);
330 } else {
331 // Is a constant with NO inputs?
332 if (parent_node->req() == 1) {
333 parent_node->set_req(0, _root);
334 }
335 }
336 }
337
338 // First, visit all inputs and force them to get a block. If an
339 // input is already in a block we quit following inputs (to avoid
340 // cycles). Instead we put that Node on a worklist to be handled
341 // later (since IT'S inputs may not have a block yet).
342
343 // Assume all n's inputs will be processed
344 bool done = true;
345
346 while (input_index < parent_node->len()) {
347 Node* in = parent_node->in(input_index++);
348 if (in == nullptr) {
349 continue;
350 }
351
352 int is_visited = visited.test_set(in->_idx);
353 if (!has_block(in)) {
354 if (is_visited) {
355 assert(false, "graph should be schedulable");
356 return false;
357 }
358 // Save parent node and next input's index.
359 nstack.push(parent_node, input_index);
360 // Process current input now.
361 parent_node = in;
362 input_index = 0;
363 // Not all n's inputs processed.
364 done = false;
365 break;
366 } else if (!is_visited) {
367 // Visit this guy later, using worklist
368 roots.push(in, 0);
369 }
370 }
371
372 if (done) {
373 // All of n's inputs have been processed, complete post-processing.
374
375 // Some instructions are pinned into a block. These include Region,
376 // Phi, Start, Return, and other control-dependent instructions and
377 // any projections which depend on them.
378 if (!parent_node->pinned()) {
379 // Set earliest legal block.
380 Block* earliest_block = find_deepest_input(parent_node, this);
381 if (C->failing()) {
382 return false;
383 }
384 map_node_to_block(parent_node, earliest_block);
385 } else {
386 assert(get_block_for_node(parent_node) == get_block_for_node(parent_node->in(0)), "Pinned Node should be at the same block as its control edge");
387 }
388
389 if (nstack.is_empty()) {
390 // Finished all nodes on stack.
391 // Process next node on the worklist 'roots'.
392 break;
393 }
394 // Get saved parent node and next input's index.
395 parent_node = nstack.node();
396 input_index = nstack.index();
397 nstack.pop();
398 }
399 }
400 }
401 return true;
402 }
403
404 //------------------------------dom_lca----------------------------------------
405 // Find least common ancestor in dominator tree
406 // LCA is a current notion of LCA, to be raised above 'this'.
407 // As a convenient boundary condition, return 'this' if LCA is null.
408 // Find the LCA of those two nodes.
409 Block* Block::dom_lca(Block* LCA) {
410 if (LCA == nullptr || LCA == this) return this;
411
412 Block* anc = this;
413 while (anc->_dom_depth > LCA->_dom_depth)
414 anc = anc->_idom; // Walk up till anc is as high as LCA
415
416 while (LCA->_dom_depth > anc->_dom_depth)
417 LCA = LCA->_idom; // Walk up till LCA is as high as anc
418
419 while (LCA != anc) { // Walk both up till they are the same
420 LCA = LCA->_idom;
421 anc = anc->_idom;
422 }
423
424 return LCA;
425 }
426
427 //--------------------------raise_LCA_above_use--------------------------------
428 // We are placing a definition, and have been given a def->use edge.
429 // The definition must dominate the use, so move the LCA upward in the
430 // dominator tree to dominate the use. If the use is a phi, adjust
431 // the LCA only with the phi input paths which actually use this def.
432 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, const PhaseCFG* cfg) {
433 Block* buse = cfg->get_block_for_node(use);
434 if (buse == nullptr) return LCA; // Unused killing Projs have no use block
435 if (!use->is_Phi()) return buse->dom_lca(LCA);
436 uint pmax = use->req(); // Number of Phi inputs
437 // Why does not this loop just break after finding the matching input to
438 // the Phi? Well...it's like this. I do not have true def-use/use-def
439 // chains. Means I cannot distinguish, from the def-use direction, which
440 // of many use-defs lead from the same use to the same def. That is, this
441 // Phi might have several uses of the same def. Each use appears in a
442 // different predecessor block. But when I enter here, I cannot distinguish
443 // which use-def edge I should find the predecessor block for. So I find
444 // them all. Means I do a little extra work if a Phi uses the same value
445 // more than once.
446 for (uint j=1; j<pmax; j++) { // For all inputs
447 if (use->in(j) == def) { // Found matching input?
448 Block* pred = cfg->get_block_for_node(buse->pred(j));
449 LCA = pred->dom_lca(LCA);
450 }
451 }
452 return LCA;
453 }
454
455 //----------------------------raise_LCA_above_marks----------------------------
456 // Return a new LCA that dominates LCA and any of its marked predecessors.
457 // Search all my parents up to 'early' (exclusive), looking for predecessors
458 // which are marked with the given index. Return the LCA (in the dom tree)
459 // of all marked blocks. If there are none marked, return the original
460 // LCA.
461 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, Block* early, const PhaseCFG* cfg) {
462 assert(early->dominates(LCA), "precondition failed");
463 Block_List worklist;
464 worklist.push(LCA);
465 while (worklist.size() > 0) {
466 Block* mid = worklist.pop();
467 if (mid == early) continue; // stop searching here
468
469 // Test and set the visited bit.
470 if (mid->raise_LCA_visited() == mark) continue; // already visited
471
472 // Don't process the current LCA, otherwise the search may terminate early
473 if (mid != LCA && mid->raise_LCA_mark() == mark) {
474 // Raise the LCA.
475 LCA = mid->dom_lca(LCA);
476 if (LCA == early) break; // stop searching everywhere
477 assert(early->dominates(LCA), "unsound LCA update");
478 // Resume searching at that point, skipping intermediate levels.
479 worklist.push(LCA);
480 if (LCA == mid)
481 continue; // Don't mark as visited to avoid early termination.
482 } else {
483 // Keep searching through this block's predecessors.
484 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) {
485 Block* mid_parent = cfg->get_block_for_node(mid->pred(j));
486 worklist.push(mid_parent);
487 }
488 }
489 mid->set_raise_LCA_visited(mark);
490 }
491 return LCA;
492 }
493
494 //--------------------------memory_early_block--------------------------------
495 // This is a variation of find_deepest_input, the heart of schedule_early.
496 // Find the "early" block for a load, if we considered only memory and
497 // address inputs, that is, if other data inputs were ignored.
498 //
499 // Because a subset of edges are considered, the resulting block will
500 // be earlier (at a shallower dom_depth) than the true schedule_early
501 // point of the node. We compute this earlier block as a more permissive
502 // site for anti-dependency insertion, but only if subsume_loads is enabled.
503 static Block* memory_early_block(Node* load, Block* early, const PhaseCFG* cfg) {
504 Node* base;
505 Node* index;
506 Node* store = load->in(MemNode::Memory);
507 load->as_Mach()->memory_inputs(base, index);
508
509 assert(base != NodeSentinel && index != NodeSentinel,
510 "unexpected base/index inputs");
511
512 Node* mem_inputs[4];
513 int mem_inputs_length = 0;
514 if (base != nullptr) mem_inputs[mem_inputs_length++] = base;
515 if (index != nullptr) mem_inputs[mem_inputs_length++] = index;
516 if (store != nullptr) mem_inputs[mem_inputs_length++] = store;
517
518 // In the comparison below, add one to account for the control input,
519 // which may be null, but always takes up a spot in the in array.
520 if (mem_inputs_length + 1 < (int) load->req()) {
521 // This "load" has more inputs than just the memory, base and index inputs.
522 // For purposes of checking anti-dependences, we need to start
523 // from the early block of only the address portion of the instruction,
524 // and ignore other blocks that may have factored into the wider
525 // schedule_early calculation.
526 if (load->in(0) != nullptr) mem_inputs[mem_inputs_length++] = load->in(0);
527
528 Block* deepb = nullptr; // Deepest block so far
529 int deepb_dom_depth = 0;
530 for (int i = 0; i < mem_inputs_length; i++) {
531 Block* inb = cfg->get_block_for_node(mem_inputs[i]);
532 if (deepb_dom_depth < (int) inb->_dom_depth) {
533 // The new inb must be dominated by the previous deepb.
534 // The various inputs must be linearly ordered in the dom
535 // tree, or else there will not be a unique deepest block.
536 assert_dom(deepb, inb, load, cfg);
537 if (cfg->C->failing()) {
538 return nullptr;
539 }
540 deepb = inb; // Save deepest block
541 deepb_dom_depth = deepb->_dom_depth;
542 }
543 }
544 early = deepb;
545 }
546
547 return early;
548 }
549
550 // This function is used by raise_above_anti_dependences to find unrelated loads for stores in implicit null checks.
551 bool PhaseCFG::unrelated_load_in_store_null_block(Node* store, Node* load) {
552 // We expect an anti-dependence edge from 'load' to 'store', except when
553 // implicit_null_check() has hoisted 'store' above its early block to
554 // perform an implicit null check, and 'load' is placed in the null
555 // block. In this case it is safe to ignore the anti-dependence, as the
556 // null block is only reached if 'store' tries to write to null object and
557 // 'load' read from non-null object (there is preceding check for that)
558 // These objects can't be the same.
559 Block* store_block = get_block_for_node(store);
560 Block* load_block = get_block_for_node(load);
561 Node* end = store_block->end();
562 if (end->is_MachNullCheck() && (end->in(1) == store) && store_block->dominates(load_block)) {
563 Node* if_true = end->find_out_with(Op_IfTrue);
564 assert(if_true != nullptr, "null check without null projection");
565 Node* null_block_region = if_true->find_out_with(Op_Region);
566 assert(null_block_region != nullptr, "null check without null region");
567 return get_block_for_node(null_block_region) == load_block;
568 }
569 return false;
570 }
571
572 class DefUseMemStatesQueue : public StackObj {
573 private:
574 class DefUsePair : public StackObj {
575 private:
576 Node* _def; // memory state
577 Node* _use; // use of the memory state that also modifies the memory state
578
579 public:
580 DefUsePair(Node* def, Node* use) :
581 _def(def), _use(use) {
582 }
583
584 DefUsePair() :
585 _def(nullptr), _use(nullptr) {
586 }
587
588 Node* def() const {
589 return _def;
590 }
591
592 Node* use() const {
593 return _use;
594 }
595 };
596
597 GrowableArray<DefUsePair> _queue;
598 GrowableArray<MergeMemNode*> _worklist_visited; // visited mergemem nodes
599
600 bool already_enqueued(Node* def_mem, PhiNode* use_phi) const {
601 // def_mem is one of the inputs of use_phi and at least one input of use_phi is
602 // not def_mem. It's however possible that use_phi has def_mem as input multiple
603 // times. If that happens, use_phi is recorded as a use of def_mem multiple
604 // times as well. When PhaseCFG::raise_above_anti_dependences() goes over
605 // uses of def_mem and enqueues them for processing, use_phi would then be
606 // enqueued for processing multiple times when it only needs to be
607 // processed once. The code below checks if use_phi as a use of def_mem was
608 // already enqueued to avoid redundant processing of use_phi.
609 int j = _queue.length()-1;
610 // If there are any use of def_mem already enqueued, they were enqueued
611 // last (all use of def_mem are processed in one go).
612 for (; j >= 0; j--) {
613 const DefUsePair& def_use_pair = _queue.at(j);
614 if (def_use_pair.def() != def_mem) {
615 // We're done with the uses of def_mem
616 break;
617 }
618 if (def_use_pair.use() == use_phi) {
619 return true;
620 }
621 }
622 #ifdef ASSERT
623 for (; j >= 0; j--) {
624 const DefUsePair& def_use_pair = _queue.at(j);
625 assert(def_use_pair.def() != def_mem, "Should be done with the uses of def_mem");
626 }
627 #endif
628 return false;
629 }
630
631 public:
632 DefUseMemStatesQueue(ResourceArea* area) {
633 }
634
635 void push(Node* def_mem_state, Node* use_mem_state) {
636 if (use_mem_state->is_MergeMem()) {
637 // Be sure we don't get into combinatorial problems.
638 if (!_worklist_visited.append_if_missing(use_mem_state->as_MergeMem())) {
639 return; // already on work list; do not repeat
640 }
641 } else if (use_mem_state->is_Phi()) {
642 // A Phi could have the same mem as input multiple times. If that's the case, we don't need to enqueue it
643 // more than once. We otherwise allow phis to be repeated; they can merge two relevant states.
644 if (already_enqueued(def_mem_state, use_mem_state->as_Phi())) {
645 return;
646 }
647 }
648
649 _queue.push(DefUsePair(def_mem_state, use_mem_state));
650 }
651
652 bool is_nonempty() const {
653 return _queue.is_nonempty();
654 }
655
656 Node* top_def() const {
657 return _queue.top().def();
658 }
659
660 Node* top_use() const {
661 return _queue.top().use();
662 }
663
664 void pop() {
665 _queue.pop();
666 }
667 };
668
669 // Enforce a scheduling of the given 'load' that ensures anti-dependent stores
670 // do not overwrite the load's input memory state before the load executes.
671 //
672 // The given 'load' has a current scheduling range in the dominator tree that
673 // starts at the load's early block (computed in schedule_early) and ends at
674 // the given 'LCA' block for the load. However, there may still exist
675 // anti-dependent stores between the early block and the LCA that overwrite
676 // memory that the load must witness. For such stores, we must
677 //
678 // 1. raise the load's LCA to force the load to (eventually) be scheduled at
679 // latest in the store's block, and
680 // 2. if the load may get scheduled in the store's block, additionally insert
681 // an anti-dependence edge (i.e., precedence edge) from the load to the
682 // store to ensure LCM schedules the load before the store within the
683 // block.
684 //
685 // For a given store, we say that the store is on a _distinct_ control-flow
686 // path relative to the load if there are no paths from early to LCA that go
687 // through the store's block. Such stores are not anti-dependent, and there is
688 // no need to update the LCA nor to add anti-dependence edges.
689 //
690 // Due to the presence of loops, we must also raise the LCA above
691 // anti-dependent memory Phis. We defer the details (see later comments in the
692 // method) and for now look at an example without loops.
693 //
694 // CFG DOMINATOR TREE
695 //
696 // B1 (early,L) B1
697 // |\________ /\\___
698 // | \ / \ \
699 // B2 (L,S) \ B2 B7 B6
700 // / \ \ /\\___
701 // B3 B4 (S) B7 (S) / \ \
702 // \ / / B3 B4 B5
703 // B5 (LCA,L) /
704 // \ ____/
705 // \ /
706 // B6
707 //
708 // Here, the load's scheduling range when calling raise_above_anti_dependences
709 // is between early and LCA in the dominator tree, i.e., in block B1, B2, or B5
710 // (indicated with "L"). However, there are a number of stores (indicated with
711 // "S") that overwrite the memory which the load must witness. First, consider
712 // the store in B4. We cannot legally schedule the load in B4, so an
713 // anti-dependence edge is redundant. However, we must raise the LCA above
714 // B4, which means that the updated LCA is B2. Now, consider the store in B2.
715 // The LCA is already B2, so we do not need to raise it any further.
716 // If we, eventually, decide to schedule the load in B2, it could happen that
717 // LCM decides to place the load after the anti-dependent store in B2.
718 // Therefore, we now need to add an anti-dependence edge between the load and
719 // the B2 store, ensuring that the load is scheduled before the store. Finally,
720 // the store in B7 is on a distinct control-flow path. Therefore, B7 requires
721 // no action.
722 //
723 // The raise_above_anti_dependences method returns the updated LCA and ensures
724 // there are no anti-dependent stores in any block between the load's early
725 // block and the updated LCA. Any stores in the updated LCA will have new
726 // anti-dependence edges back to the load. The caller may schedule the load in
727 // the updated LCA, or it may hoist the load above the updated LCA, if the
728 // updated LCA is not the early block.
729 Block* PhaseCFG::raise_above_anti_dependences(Block* LCA, Node* load, const bool verify) {
730 ResourceMark rm;
731 assert(load->needs_anti_dependence_check(), "must be a load of some sort");
732 assert(LCA != nullptr, "");
733 DEBUG_ONLY(Block* LCA_orig = LCA);
734
735 // Compute the alias index. Loads and stores with different alias indices
736 // do not need anti-dependence edges.
737 int load_alias_idx = C->get_alias_index(load->adr_type());
738 #ifdef ASSERT
739 assert(Compile::AliasIdxTop <= load_alias_idx && load_alias_idx < C->num_alias_types(), "Invalid alias index");
740 if (load_alias_idx == Compile::AliasIdxBot && C->do_aliasing() &&
741 (PrintOpto || VerifyAliases ||
742 (PrintMiscellaneous && (WizardMode || Verbose)))) {
743 // Load nodes should not consume all of memory.
744 // Reporting a bottom type indicates a bug in adlc.
745 // If some particular type of node validly consumes all of memory,
746 // sharpen the preceding "if" to exclude it, so we can catch bugs here.
747 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory.");
748 load->dump(2);
749 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, "");
750 }
751 #endif
752
753 if (!C->alias_type(load_alias_idx)->is_rewritable()) {
754 // It is impossible to spoil this load by putting stores before it,
755 // because we know that the stores will never update the value
756 // which 'load' must witness.
757 return LCA;
758 }
759
760 node_idx_t load_index = load->_idx;
761
762 // Record the earliest legal placement of 'load', as determined by the unique
763 // point in the dominator tree where all memory effects and other inputs are
764 // first available (computed by schedule_early). For normal loads, 'early' is
765 // the shallowest place (dominator-tree wise) to look for anti-dependences
766 // between this load and any store.
767 Block* early = get_block_for_node(load);
768
769 // If we are subsuming loads, compute an "early" block that only considers
770 // memory or address inputs. This block may be different from the
771 // schedule_early block when it is at an even shallower depth in the
772 // dominator tree, and allow for a broader discovery of anti-dependences.
773 if (C->subsume_loads()) {
774 early = memory_early_block(load, early, this);
775 if (C->failing()) {
776 return nullptr;
777 }
778 }
779
780 assert(early->dominates(LCA_orig), "precondition failed");
781
782 ResourceArea* area = Thread::current()->resource_area();
783
784 // Bookkeeping of possibly anti-dependent stores that we find outside the
785 // early block and that may need anti-dependence edges. Note that stores in
786 // non_early_stores are not necessarily dominated by early. The search starts
787 // from initial_mem, which can reside in a block that dominates early, and
788 // therefore, stores we find may be in blocks that are on completely distinct
789 // control-flow paths compared to early. However, in the end, only stores in
790 // blocks dominated by early matter. The reason for bookkeeping not only
791 // relevant stores is efficiency: we lazily record all possible
792 // anti-dependent stores and add anti-dependence edges only to the relevant
793 // ones at the very end of this method when we know the final updated LCA.
794 Node_List non_early_stores(area);
795
796 // Whether we must raise the LCA after the main worklist loop below.
797 bool must_raise_LCA_above_marks = false;
798
799 // The input load uses some memory state (initial_mem).
800 Node* initial_mem = load->in(MemNode::Memory);
801 // To find anti-dependences we must look for users of the same memory state.
802 // To do this, we search the memory graph downwards from initial_mem. During
803 // this search, we encounter different types of nodes that we handle
804 // according to the following three categories:
805 //
806 // - MergeMems
807 // - Memory-state-modifying nodes (informally referred to as "stores" above
808 // and below)
809 // - Memory Phis
810 //
811 // MergeMems do not modify the memory state. Anti-dependent stores or memory
812 // Phis may, however, exist downstream of MergeMems. Therefore, we must
813 // permit the search to continue through MergeMems. Stores may raise the LCA
814 // and may potentially also require an anti-dependence edge. Memory Phis may
815 // raise the LCA but never require anti-dependence edges. See the comments
816 // throughout the worklist loop below for further details.
817 //
818 // It may be useful to think of the anti-dependence search as traversing a
819 // tree rooted at initial_mem, with internal nodes of type MergeMem and
820 // memory Phis and stores as (potentially repeated) leaves.
821
822 // We don't optimize the memory graph for pinned loads, so we may need to raise the
823 // root of our search tree through the corresponding slices of MergeMem nodes to
824 // get to the node that really creates the memory state for this slice.
825 if (load_alias_idx >= Compile::AliasIdxRaw) {
826 while (initial_mem->is_MergeMem()) {
827 MergeMemNode* mm = initial_mem->as_MergeMem();
828 Node* p = mm->memory_at(load_alias_idx);
829 if (p != mm->base_memory()) {
830 initial_mem = p;
831 } else {
832 break;
833 }
834 }
835 }
836 // To administer the search, we use a worklist consisting of (def,use)-pairs
837 // of memory states, corresponding to edges in the search tree (and edges
838 // in the memory graph). We need to keep track of search tree edges in the
839 // worklist rather than individual nodes due to memory Phis (see details
840 // below).
841 DefUseMemStatesQueue worklist(area);
842 // We start the search at initial_mem and indicate the search root with the
843 // edge (nullptr, initial_mem).
844 worklist.push(nullptr, initial_mem);
845
846 // The worklist loop
847 while (worklist.is_nonempty()) {
848 // Pop the next edge from the worklist
849 Node* def_mem_state = worklist.top_def();
850 Node* use_mem_state = worklist.top_use();
851 worklist.pop();
852
853 // We are either
854 // - at the root of the search with the edge (nullptr, initial_mem),
855 // - just past initial_mem with the edge (initial_mem, use_mem_state), or
856 // - just past a MergeMem with the edge (MergeMem, use_mem_state).
857 assert(def_mem_state == nullptr || def_mem_state == initial_mem ||
858 def_mem_state->is_MergeMem(),
859 "unexpected memory state");
860
861 const uint op = use_mem_state->Opcode();
862
863 #ifdef ASSERT
864 // CacheWB nodes are peculiar in a sense that they both are anti-dependent and produce memory.
865 // Allow them to be treated as a store.
866 bool is_cache_wb = false;
867 if (use_mem_state->is_Mach()) {
868 int ideal_op = use_mem_state->as_Mach()->ideal_Opcode();
869 is_cache_wb = (ideal_op == Op_CacheWB);
870 }
871 assert(!use_mem_state->needs_anti_dependence_check() || is_cache_wb, "no loads");
872 #endif
873
874 // If we are either at the search root or have found a MergeMem, we step
875 // past use_mem_state and populate the search worklist with edges
876 // (use_mem_state, child) for use_mem_state's children.
877 if (def_mem_state == nullptr // root (exclusive) of tree we are searching
878 || op == Op_MergeMem // internal node of tree we are searching
879 ) {
880 def_mem_state = use_mem_state;
881
882 for (DUIterator_Fast imax, i = def_mem_state->fast_outs(imax); i < imax; i++) {
883 use_mem_state = def_mem_state->fast_out(i);
884 if (use_mem_state->needs_anti_dependence_check()) {
885 // use_mem_state is also a kind of load (i.e.,
886 // needs_anti_dependence_check), and it is not a store nor a memory
887 // Phi. Hence, it is not anti-dependent on the load.
888 continue;
889 }
890 worklist.push(def_mem_state, use_mem_state);
891 }
892 // Nothing more to do for the current (nullptr, initial_mem) or
893 // (initial_mem/MergeMem, MergeMem) edge, move on.
894 continue;
895 }
896
897 assert(!use_mem_state->is_MergeMem(),
898 "use_mem_state should be either a store or a memory Phi");
899
900 if (op == Op_MachProj || op == Op_Catch) continue;
901
902 // Compute the alias index. If the use_mem_state has an alias index
903 // different from the load's, it is not anti-dependent. Wide MemBar's
904 // are anti-dependent with everything (except immutable memories).
905 const TypePtr* adr_type = use_mem_state->adr_type();
906 if (!C->can_alias(adr_type, load_alias_idx)) continue;
907
908 // Most slow-path runtime calls do NOT modify Java memory, but
909 // they can block and so write Raw memory.
910 if (use_mem_state->is_Mach()) {
911 MachNode* muse = use_mem_state->as_Mach();
912 if (load_alias_idx != Compile::AliasIdxRaw) {
913 // Check for call into the runtime using the Java calling
914 // convention (and from there into a wrapper); it has no
915 // _method. Can't do this optimization for Native calls because
916 // they CAN write to Java memory.
917 if (muse->ideal_Opcode() == Op_CallStaticJava) {
918 assert(muse->is_MachSafePoint(), "");
919 MachSafePointNode* ms = (MachSafePointNode*)muse;
920 assert(ms->is_MachCallJava(), "");
921 MachCallJavaNode* mcj = (MachCallJavaNode*) ms;
922 if (mcj->_method == nullptr) {
923 // These runtime calls do not write to Java visible memory
924 // (other than Raw) and so are not anti-dependent.
925 continue;
926 }
927 }
928 // Same for SafePoints: they read/write Raw but only read otherwise.
929 // This is basically a workaround for SafePoints only defining control
930 // instead of control + memory.
931 if (muse->ideal_Opcode() == Op_SafePoint) {
932 continue;
933 }
934 } else {
935 // Some raw memory, such as the load of "top" at an allocation,
936 // can be control dependent on the previous safepoint. See
937 // comments in GraphKit::allocate_heap() about control input.
938 // Inserting an anti-dependence edge between such a safepoint and a use
939 // creates a cycle, and will cause a subsequent failure in
940 // local scheduling. (BugId 4919904)
941 // (%%% How can a control input be a safepoint and not a projection??)
942 if (muse->ideal_Opcode() == Op_SafePoint && load->in(0) == muse) {
943 continue;
944 }
945 }
946 }
947
948 // Determine the block of the use_mem_state.
949 Block* use_mem_state_block = get_block_for_node(use_mem_state);
950 assert(use_mem_state_block != nullptr,
951 "unused killing projections skipped above");
952
953 // For efficiency, we take a lazy approach to both raising the LCA and
954 // adding anti-dependence edges. In this worklist loop, we only mark blocks
955 // which we must raise the LCA above (set_raise_LCA_mark), and keep
956 // track of nodes that potentially need anti-dependence edges
957 // (non_early_stores). The only exceptions to this are if we
958 // immediately see that we have to raise the LCA all the way to the early
959 // block, and if we find stores in the early block (which always need
960 // anti-dependence edges).
961 //
962 // After the worklist loop, we perform an efficient combined LCA-raising
963 // operation over all marks and only then add anti-dependence edges where
964 // strictly necessary according to the new raised LCA.
965
966 if (use_mem_state->is_Phi()) {
967 // We have reached a memory Phi node. On our search from initial_mem to
968 // the Phi, we have found no anti-dependences (otherwise, we would have
969 // already terminated the search along this branch). Consider the example
970 // below, indicating a Phi node and its node inputs (we omit the control
971 // input).
972 //
973 // def_mem_state
974 // |
975 // | ? ?
976 // \ | /
977 // Phi
978 //
979 // We reached the Phi from def_mem_state and know that, on this
980 // particular input, the memory that the load must witness is not
981 // overwritten. However, for the Phi's other inputs (? in the
982 // illustration), we have no information and must thus conservatively
983 // assume that the load's memory is overwritten at and below the Phi.
984 //
985 // It is impossible to schedule the load before the Phi in
986 // the same block as the Phi (use_mem_state_block), and anti-dependence
987 // edges are, therefore, redundant. We must, however, find the
988 // predecessor block of use_mem_state_block that corresponds to
989 // def_mem_state, and raise the LCA above that block. Note that this block
990 // is not necessarily def_mem_state's block! See the continuation of our
991 // previous example below (now illustrating blocks instead of nodes)
992 //
993 // def_mem_state's block
994 // |
995 // |
996 // pred_block
997 // |
998 // | ? ?
999 // | | |
1000 // use_mem_state_block
1001 //
1002 // Here, we must raise the LCA above pred_block rather than
1003 // def_mem_state's block.
1004 //
1005 // Do not assert(use_mem_state_block != early, "Phi merging memory after access")
1006 // PhiNode may be at start of block 'early' with backedge to 'early'
1007 if (LCA == early) {
1008 // Don't bother if LCA is already raised all the way
1009 continue;
1010 }
1011 DEBUG_ONLY(bool found_match = false);
1012 for (uint j = PhiNode::Input, jmax = use_mem_state->req(); j < jmax; j++) {
1013 if (use_mem_state->in(j) == def_mem_state) { // Found matching input?
1014 DEBUG_ONLY(found_match = true);
1015 Block* pred_block = get_block_for_node(use_mem_state_block->pred(j));
1016 if (pred_block != early) {
1017 // Lazily set the LCA mark
1018 pred_block->set_raise_LCA_mark(load_index);
1019 must_raise_LCA_above_marks = true;
1020 } else /* if (pred_block == early) */ {
1021 // We know already now that we must raise LCA all the way to early.
1022 LCA = early;
1023 // This turns off the process of gathering non_early_stores.
1024 }
1025 }
1026 }
1027 assert(found_match, "no worklist bug");
1028 } else if (use_mem_state_block != early) {
1029 // We found an anti-dependent store outside the load's 'early' block. The
1030 // store may be between the current LCA and the earliest possible block
1031 // (but it could very well also be on a distinct control-flow path).
1032 // Lazily set the LCA mark and push to non_early_stores.
1033 if (LCA == early) {
1034 // Don't bother if LCA is already raised all the way
1035 continue;
1036 }
1037 if (unrelated_load_in_store_null_block(use_mem_state, load)) {
1038 continue;
1039 }
1040 use_mem_state_block->set_raise_LCA_mark(load_index);
1041 must_raise_LCA_above_marks = true;
1042 non_early_stores.push(use_mem_state);
1043 } else /* if (use_mem_state_block == early) */ {
1044 // We found an anti-dependent store in the load's 'early' block.
1045 // Therefore, we know already now that we must raise LCA all the way to
1046 // early and that we need to add an anti-dependence edge to the store.
1047 assert(use_mem_state != load->find_exact_control(load->in(0)), "dependence cycle found");
1048 if (verify) {
1049 assert(use_mem_state->find_edge(load) != -1 || unrelated_load_in_store_null_block(use_mem_state, load),
1050 "missing precedence edge");
1051 } else {
1052 use_mem_state->add_prec(load);
1053 }
1054 LCA = early;
1055 // This turns off the process of gathering non_early_stores.
1056 }
1057 }
1058 // Worklist is now empty; we have visited all possible anti-dependences.
1059
1060 // Finished if 'load' must be scheduled in its 'early' block.
1061 // If we found any stores there, they have already been given
1062 // anti-dependence edges.
1063 if (LCA == early) {
1064 return LCA;
1065 }
1066
1067 // We get here only if there are no anti-dependent stores in the load's
1068 // 'early' block and if no memory Phi has forced LCA to the early block. Now
1069 // we must raise the LCA above the blocks for all the anti-dependent stores
1070 // and above the predecessor blocks of anti-dependent memory Phis we reached
1071 // during the search.
1072 if (must_raise_LCA_above_marks) {
1073 LCA = raise_LCA_above_marks(LCA, load->_idx, early, this);
1074 }
1075
1076 // If LCA == early at this point, there were no stores that required
1077 // anti-dependence edges in the early block. Otherwise, we would have eagerly
1078 // raised the LCA to early already in the worklist loop.
1079 if (LCA == early) {
1080 return LCA;
1081 }
1082
1083 // The raised LCA block can now be a home to anti-dependent stores for which
1084 // we still need to add anti-dependence edges, but no LCA predecessor block
1085 // contains any such stores (otherwise, we would have raised the LCA even
1086 // higher).
1087 //
1088 // The raised LCA will be a lower bound for placing the load, preventing the
1089 // load from sinking past any block containing a store that may overwrite
1090 // memory that the load must witness.
1091 //
1092 // Now we need to insert the necessary anti-dependence edges from 'load' to
1093 // each store in the non-early LCA block. We have recorded all such potential
1094 // stores in non_early_stores.
1095 //
1096 // If LCA->raise_LCA_mark() != load_index, it means that we raised the LCA to
1097 // a block in which we did not find any anti-dependent stores. So, no need to
1098 // search for any such stores.
1099 if (LCA->raise_LCA_mark() == load_index) {
1100 while (non_early_stores.size() > 0) {
1101 Node* store = non_early_stores.pop();
1102 Block* store_block = get_block_for_node(store);
1103 if (store_block == LCA) {
1104 // Add anti-dependence edge from the load to the store in the non-early
1105 // LCA.
1106 assert(store != load->find_exact_control(load->in(0)), "dependence cycle found");
1107 if (verify) {
1108 assert(store->find_edge(load) != -1, "missing precedence edge");
1109 } else {
1110 store->add_prec(load);
1111 }
1112 } else {
1113 assert(store_block->raise_LCA_mark() == load_index, "block was marked");
1114 }
1115 }
1116 }
1117
1118 assert(LCA->dominates(LCA_orig), "unsound updated LCA");
1119
1120 // Return the highest block containing stores; any stores
1121 // within that block have been given anti-dependence edges.
1122 return LCA;
1123 }
1124
1125 // This class is used to iterate backwards over the nodes in the graph.
1126
1127 class Node_Backward_Iterator {
1128
1129 private:
1130 Node_Backward_Iterator();
1131
1132 public:
1133 // Constructor for the iterator
1134 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_Stack &stack, PhaseCFG &cfg);
1135
1136 // Postincrement operator to iterate over the nodes
1137 Node *next();
1138
1139 private:
1140 VectorSet &_visited;
1141 Node_Stack &_stack;
1142 PhaseCFG &_cfg;
1143 };
1144
1145 // Constructor for the Node_Backward_Iterator
1146 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_Stack &stack, PhaseCFG &cfg)
1147 : _visited(visited), _stack(stack), _cfg(cfg) {
1148 // The stack should contain exactly the root
1149 stack.clear();
1150 stack.push(root, root->outcnt());
1151
1152 // Clear the visited bits
1153 visited.clear();
1154 }
1155
1156 // Iterator for the Node_Backward_Iterator
1157 Node *Node_Backward_Iterator::next() {
1158
1159 // If the _stack is empty, then just return null: finished.
1160 if ( !_stack.size() )
1161 return nullptr;
1162
1163 // I visit unvisited not-anti-dependence users first, then anti-dependent
1164 // children next. I iterate backwards to support removal of nodes.
1165 // The stack holds states consisting of 3 values:
1166 // current Def node, flag which indicates 1st/2nd pass, index of current out edge
1167 Node *self = (Node*)(((uintptr_t)_stack.node()) & ~1);
1168 bool iterate_anti_dep = (((uintptr_t)_stack.node()) & 1);
1169 uint idx = MIN2(_stack.index(), self->outcnt()); // Support removal of nodes.
1170 _stack.pop();
1171
1172 // I cycle here when I am entering a deeper level of recursion.
1173 // The key variable 'self' was set prior to jumping here.
1174 while( 1 ) {
1175
1176 _visited.set(self->_idx);
1177
1178 // Now schedule all uses as late as possible.
1179 const Node* src = self->is_Proj() ? self->in(0) : self;
1180 uint src_rpo = _cfg.get_block_for_node(src)->_rpo;
1181
1182 // Schedule all nodes in a post-order visit
1183 Node *unvisited = nullptr; // Unvisited anti-dependent Node, if any
1184
1185 // Scan for unvisited nodes
1186 while (idx > 0) {
1187 // For all uses, schedule late
1188 Node* n = self->raw_out(--idx); // Use
1189
1190 // Skip already visited children
1191 if ( _visited.test(n->_idx) )
1192 continue;
1193
1194 // do not traverse backward control edges
1195 Node *use = n->is_Proj() ? n->in(0) : n;
1196 uint use_rpo = _cfg.get_block_for_node(use)->_rpo;
1197
1198 if ( use_rpo < src_rpo )
1199 continue;
1200
1201 // Phi nodes always precede uses in a basic block
1202 if ( use_rpo == src_rpo && use->is_Phi() )
1203 continue;
1204
1205 unvisited = n; // Found unvisited
1206
1207 // Check for possible-anti-dependent
1208 // 1st pass: No such nodes, 2nd pass: Only such nodes.
1209 if (n->needs_anti_dependence_check() == iterate_anti_dep) {
1210 unvisited = n; // Found unvisited
1211 break;
1212 }
1213 }
1214
1215 // Did I find an unvisited not-anti-dependent Node?
1216 if (!unvisited) {
1217 if (!iterate_anti_dep) {
1218 // 2nd pass: Iterate over nodes which needs_anti_dependence_check.
1219 iterate_anti_dep = true;
1220 idx = self->outcnt();
1221 continue;
1222 }
1223 break; // All done with children; post-visit 'self'
1224 }
1225
1226 // Visit the unvisited Node. Contains the obvious push to
1227 // indicate I'm entering a deeper level of recursion. I push the
1228 // old state onto the _stack and set a new state and loop (recurse).
1229 _stack.push((Node*)((uintptr_t)self | (uintptr_t)iterate_anti_dep), idx);
1230 self = unvisited;
1231 iterate_anti_dep = false;
1232 idx = self->outcnt();
1233 } // End recursion loop
1234
1235 return self;
1236 }
1237
1238 //------------------------------ComputeLatenciesBackwards----------------------
1239 // Compute the latency of all the instructions.
1240 void PhaseCFG::compute_latencies_backwards(VectorSet &visited, Node_Stack &stack) {
1241 #ifndef PRODUCT
1242 if (trace_opto_pipelining())
1243 tty->print("\n#---- ComputeLatenciesBackwards ----\n");
1244 #endif
1245
1246 Node_Backward_Iterator iter((Node *)_root, visited, stack, *this);
1247 Node *n;
1248
1249 // Walk over all the nodes from last to first
1250 while ((n = iter.next())) {
1251 // Set the latency for the definitions of this instruction
1252 partial_latency_of_defs(n);
1253 }
1254 } // end ComputeLatenciesBackwards
1255
1256 //------------------------------partial_latency_of_defs------------------------
1257 // Compute the latency impact of this node on all defs. This computes
1258 // a number that increases as we approach the beginning of the routine.
1259 void PhaseCFG::partial_latency_of_defs(Node *n) {
1260 // Set the latency for this instruction
1261 #ifndef PRODUCT
1262 if (trace_opto_pipelining()) {
1263 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", n->_idx, get_latency_for_node(n));
1264 dump();
1265 }
1266 #endif
1267
1268 if (n->is_Proj()) {
1269 n = n->in(0);
1270 }
1271
1272 if (n->is_Root()) {
1273 return;
1274 }
1275
1276 uint nlen = n->len();
1277 uint use_latency = get_latency_for_node(n);
1278 uint use_pre_order = get_block_for_node(n)->_pre_order;
1279
1280 for (uint j = 0; j < nlen; j++) {
1281 Node *def = n->in(j);
1282
1283 if (!def || def == n) {
1284 continue;
1285 }
1286
1287 // Walk backwards thru projections
1288 if (def->is_Proj()) {
1289 def = def->in(0);
1290 }
1291
1292 #ifndef PRODUCT
1293 if (trace_opto_pipelining()) {
1294 tty->print("# in(%2d): ", j);
1295 def->dump();
1296 }
1297 #endif
1298
1299 // If the defining block is not known, assume it is ok
1300 Block *def_block = get_block_for_node(def);
1301 uint def_pre_order = def_block ? def_block->_pre_order : 0;
1302
1303 if ((use_pre_order < def_pre_order) || (use_pre_order == def_pre_order && n->is_Phi())) {
1304 continue;
1305 }
1306
1307 uint delta_latency = n->latency(j);
1308 uint current_latency = delta_latency + use_latency;
1309
1310 if (get_latency_for_node(def) < current_latency) {
1311 set_latency_for_node(def, current_latency);
1312 }
1313
1314 #ifndef PRODUCT
1315 if (trace_opto_pipelining()) {
1316 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", use_latency, j, delta_latency, current_latency, def->_idx, get_latency_for_node(def));
1317 }
1318 #endif
1319 }
1320 }
1321
1322 //------------------------------latency_from_use-------------------------------
1323 // Compute the latency of a specific use
1324 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) {
1325 // If self-reference, return no latency
1326 if (use == n || use->is_Root()) {
1327 return 0;
1328 }
1329
1330 uint def_pre_order = get_block_for_node(def)->_pre_order;
1331 uint latency = 0;
1332
1333 // If the use is not a projection, then it is simple...
1334 if (!use->is_Proj()) {
1335 #ifndef PRODUCT
1336 if (trace_opto_pipelining()) {
1337 tty->print("# out(): ");
1338 use->dump();
1339 }
1340 #endif
1341
1342 uint use_pre_order = get_block_for_node(use)->_pre_order;
1343
1344 if (use_pre_order < def_pre_order)
1345 return 0;
1346
1347 if (use_pre_order == def_pre_order && use->is_Phi())
1348 return 0;
1349
1350 uint nlen = use->len();
1351 uint nl = get_latency_for_node(use);
1352
1353 for ( uint j=0; j<nlen; j++ ) {
1354 if (use->in(j) == n) {
1355 // Change this if we want local latencies
1356 uint ul = use->latency(j);
1357 uint l = ul + nl;
1358 if (latency < l) latency = l;
1359 #ifndef PRODUCT
1360 if (trace_opto_pipelining()) {
1361 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d",
1362 nl, j, ul, l, latency);
1363 }
1364 #endif
1365 }
1366 }
1367 } else {
1368 // This is a projection, just grab the latency of the use(s)
1369 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) {
1370 uint l = latency_from_use(use, def, use->fast_out(j));
1371 if (latency < l) latency = l;
1372 }
1373 }
1374
1375 return latency;
1376 }
1377
1378 //------------------------------latency_from_uses------------------------------
1379 // Compute the latency of this instruction relative to all of it's uses.
1380 // This computes a number that increases as we approach the beginning of the
1381 // routine.
1382 void PhaseCFG::latency_from_uses(Node *n) {
1383 // Set the latency for this instruction
1384 #ifndef PRODUCT
1385 if (trace_opto_pipelining()) {
1386 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", n->_idx, get_latency_for_node(n));
1387 dump();
1388 }
1389 #endif
1390 uint latency=0;
1391 const Node *def = n->is_Proj() ? n->in(0): n;
1392
1393 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1394 uint l = latency_from_use(n, def, n->fast_out(i));
1395
1396 if (latency < l) latency = l;
1397 }
1398
1399 set_latency_for_node(n, latency);
1400 }
1401
1402 //------------------------------is_cheaper_block-------------------------
1403 // Check if a block between early and LCA block of uses is cheaper by
1404 // frequency-based policy, latency-based policy and random-based policy
1405 bool PhaseCFG::is_cheaper_block(Block* LCA, Node* self, uint target_latency,
1406 uint end_latency, double least_freq,
1407 int cand_cnt, bool in_latency) {
1408 if (StressGCM) {
1409 // Should be randomly accepted in stress mode
1410 return C->randomized_select(cand_cnt);
1411 }
1412
1413 const double delta = 1 + PROB_UNLIKELY_MAG(4);
1414
1415 // Better Frequency. Add a small delta to the comparison to not needlessly
1416 // hoist because of, e.g., small numerical inaccuracies.
1417 if (LCA->_freq * delta < least_freq) {
1418 return true;
1419 }
1420
1421 // Otherwise, choose with latency
1422 if (!in_latency && // No block containing latency
1423 LCA->_freq < least_freq * delta && // No worse frequency
1424 target_latency >= end_latency && // within latency range
1425 !self->is_iteratively_computed() // But don't hoist IV increments
1426 // because they may end up above other uses of their phi forcing
1427 // their result register to be different from their input.
1428 ) {
1429 return true;
1430 }
1431
1432 return false;
1433 }
1434
1435 //------------------------------hoist_to_cheaper_block-------------------------
1436 // Pick a block for node self, between early and LCA block of uses, that is a
1437 // cheaper alternative to LCA.
1438 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) {
1439 Block* least = LCA;
1440 double least_freq = least->_freq;
1441 uint target = get_latency_for_node(self);
1442 uint start_latency = get_latency_for_node(LCA->head());
1443 uint end_latency = get_latency_for_node(LCA->get_node(LCA->end_idx()));
1444 bool in_latency = (target <= start_latency);
1445 const Block* root_block = get_block_for_node(_root);
1446
1447 // Turn off latency scheduling if scheduling is just plain off
1448 if (!C->do_scheduling())
1449 in_latency = true;
1450
1451 // Do not hoist (to cover latency) instructions which target a
1452 // single register. Hoisting stretches the live range of the
1453 // single register and may force spilling.
1454 MachNode* mach = self->is_Mach() ? self->as_Mach() : nullptr;
1455 if (mach != nullptr && mach->out_RegMask().is_bound1() && !mach->out_RegMask().is_empty()) {
1456 in_latency = true;
1457 }
1458
1459 #ifndef PRODUCT
1460 if (trace_opto_pipelining()) {
1461 tty->print("# Find cheaper block for latency %d: ", get_latency_for_node(self));
1462 self->dump();
1463 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1464 LCA->_pre_order,
1465 LCA->head()->_idx,
1466 start_latency,
1467 LCA->get_node(LCA->end_idx())->_idx,
1468 end_latency,
1469 least_freq);
1470 }
1471 #endif
1472
1473 int cand_cnt = 0; // number of candidates tried
1474
1475 // Walk up the dominator tree from LCA (Lowest common ancestor) to
1476 // the earliest legal location. Capture the least execution frequency,
1477 // or choose a random block if -XX:+StressGCM, or using latency-based policy
1478 while (LCA != early) {
1479 LCA = LCA->_idom; // Follow up the dominator tree
1480
1481 if (LCA == nullptr) {
1482 // Bailout without retry
1483 assert(false, "graph should be schedulable");
1484 C->record_method_not_compilable("late schedule failed: LCA is null");
1485 return least;
1486 }
1487
1488 // Don't hoist machine instructions to the root basic block
1489 if (mach != nullptr && LCA == root_block)
1490 break;
1491
1492 if (self->is_memory_writer() &&
1493 (LCA->_loop->depth() > early->_loop->depth())) {
1494 // LCA is an invalid placement for a memory writer: choosing it would
1495 // cause memory interference, as illustrated in schedule_late().
1496 continue;
1497 }
1498 verify_memory_writer_placement(LCA, self);
1499
1500 uint start_lat = get_latency_for_node(LCA->head());
1501 uint end_idx = LCA->end_idx();
1502 uint end_lat = get_latency_for_node(LCA->get_node(end_idx));
1503 double LCA_freq = LCA->_freq;
1504 #ifndef PRODUCT
1505 if (trace_opto_pipelining()) {
1506 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1507 LCA->_pre_order, LCA->head()->_idx, start_lat, end_idx, end_lat, LCA_freq);
1508 }
1509 #endif
1510 cand_cnt++;
1511 if (is_cheaper_block(LCA, self, target, end_lat, least_freq, cand_cnt, in_latency)) {
1512 least = LCA; // Found cheaper block
1513 least_freq = LCA_freq;
1514 start_latency = start_lat;
1515 end_latency = end_lat;
1516 if (target <= start_lat)
1517 in_latency = true;
1518 }
1519 }
1520
1521 #ifndef PRODUCT
1522 if (trace_opto_pipelining()) {
1523 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g",
1524 least->_pre_order, start_latency, least_freq);
1525 }
1526 #endif
1527
1528 // See if the latency needs to be updated
1529 if (target < end_latency) {
1530 #ifndef PRODUCT
1531 if (trace_opto_pipelining()) {
1532 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency);
1533 }
1534 #endif
1535 set_latency_for_node(self, end_latency);
1536 partial_latency_of_defs(self);
1537 }
1538
1539 return least;
1540 }
1541
1542
1543 //------------------------------schedule_late-----------------------------------
1544 // Now schedule all codes as LATE as possible. This is the LCA in the
1545 // dominator tree of all USES of a value. Pick the block with the least
1546 // loop nesting depth that is lowest in the dominator tree.
1547 extern const char must_clone[];
1548 void PhaseCFG::schedule_late(VectorSet &visited, Node_Stack &stack) {
1549 #ifndef PRODUCT
1550 if (trace_opto_pipelining())
1551 tty->print("\n#---- schedule_late ----\n");
1552 #endif
1553
1554 Node_Backward_Iterator iter((Node *)_root, visited, stack, *this);
1555 Node *self;
1556
1557 // Walk over all the nodes from last to first
1558 while ((self = iter.next())) {
1559 Block* early = get_block_for_node(self); // Earliest legal placement
1560
1561 if (self->is_top()) {
1562 // Top node goes in bb #2 with other constants.
1563 // It must be special-cased, because it has no out edges.
1564 early->add_inst(self);
1565 continue;
1566 }
1567
1568 // No uses, just terminate
1569 if (self->outcnt() == 0) {
1570 assert(self->is_MachProj(), "sanity");
1571 continue; // Must be a dead machine projection
1572 }
1573
1574 // If node is pinned in the block, then no scheduling can be done.
1575 if( self->pinned() ) // Pinned in block?
1576 continue;
1577
1578 #ifdef ASSERT
1579 // Assert that memory writers (e.g. stores) have a "home" block (the block
1580 // given by their control input), and that this block corresponds to their
1581 // earliest possible placement. This guarantees that
1582 // hoist_to_cheaper_block() will always have at least one valid choice.
1583 if (self->is_memory_writer()) {
1584 assert(find_block_for_node(self->in(0)) == early,
1585 "The home of a memory writer must also be its earliest placement");
1586 }
1587 #endif
1588
1589 MachNode* mach = self->is_Mach() ? self->as_Mach() : nullptr;
1590 if (mach) {
1591 switch (mach->ideal_Opcode()) {
1592 case Op_CreateEx:
1593 // Don't move exception creation
1594 early->add_inst(self);
1595 continue;
1596 break;
1597 case Op_CastI2N:
1598 early->add_inst(self);
1599 continue;
1600 case Op_CheckCastPP: {
1601 // Don't move CheckCastPP nodes away from their input, if the input
1602 // is a rawptr (5071820).
1603 Node *def = self->in(1);
1604 if (def != nullptr && def->bottom_type()->base() == Type::RawPtr) {
1605 early->add_inst(self);
1606 #ifdef ASSERT
1607 _raw_oops.push(def);
1608 #endif
1609 continue;
1610 }
1611 break;
1612 }
1613 default:
1614 break;
1615 }
1616 if (C->has_irreducible_loop() && self->is_memory_writer()) {
1617 // If the CFG is irreducible, place memory writers in their home block.
1618 // This prevents hoist_to_cheaper_block() from accidentally placing such
1619 // nodes into deeper loops, as in the following example:
1620 //
1621 // Home placement of store in B1 (loop L1):
1622 //
1623 // B1 (L1):
1624 // m1 <- ..
1625 // m2 <- store m1, ..
1626 // B2 (L2):
1627 // jump B2
1628 // B3 (L1):
1629 // .. <- .. m2, ..
1630 //
1631 // Wrong "hoisting" of store to B2 (in loop L2, child of L1):
1632 //
1633 // B1 (L1):
1634 // m1 <- ..
1635 // B2 (L2):
1636 // m2 <- store m1, ..
1637 // # Wrong: m1 and m2 interfere at this point.
1638 // jump B2
1639 // B3 (L1):
1640 // .. <- .. m2, ..
1641 //
1642 // This "hoist inversion" can happen due to different factors such as
1643 // inaccurate estimation of frequencies for irreducible CFGs, and loops
1644 // with always-taken exits in reducible CFGs. In the reducible case,
1645 // hoist inversion is prevented by discarding invalid blocks (those in
1646 // deeper loops than the home block). In the irreducible case, the
1647 // invalid blocks cannot be identified due to incomplete loop nesting
1648 // information, hence a conservative solution is taken.
1649 #ifndef PRODUCT
1650 if (trace_opto_pipelining()) {
1651 tty->print_cr("# Irreducible loops: schedule in home block B%d:",
1652 early->_pre_order);
1653 self->dump();
1654 }
1655 #endif
1656 schedule_node_into_block(self, early);
1657 continue;
1658 }
1659 }
1660
1661 // Gather LCA of all uses
1662 Block *LCA = nullptr;
1663 {
1664 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
1665 // For all uses, find LCA
1666 Node* use = self->fast_out(i);
1667 LCA = raise_LCA_above_use(LCA, use, self, this);
1668 }
1669 guarantee(LCA != nullptr, "There must be a LCA");
1670 } // (Hide defs of imax, i from rest of block.)
1671
1672 // Place temps in the block of their use. This isn't a
1673 // requirement for correctness but it reduces useless
1674 // interference between temps and other nodes.
1675 if (mach != nullptr && mach->is_MachTemp()) {
1676 map_node_to_block(self, LCA);
1677 LCA->add_inst(self);
1678 continue;
1679 }
1680
1681 // Check if 'self' could be anti-dependent on memory
1682 if (self->needs_anti_dependence_check()) {
1683 // Hoist LCA above possible-defs and insert anti-dependences to
1684 // defs in new LCA block.
1685 LCA = raise_above_anti_dependences(LCA, self);
1686 if (C->failing()) {
1687 return;
1688 }
1689 }
1690
1691 if (early->_dom_depth > LCA->_dom_depth) {
1692 // Somehow the LCA has moved above the earliest legal point.
1693 // (One way this can happen is via memory_early_block.)
1694 if (C->subsume_loads() == true && !C->failing()) {
1695 // Retry with subsume_loads == false
1696 // If this is the first failure, the sentinel string will "stick"
1697 // to the Compile object, and the C2Compiler will see it and retry.
1698 C->record_failure(C2Compiler::retry_no_subsuming_loads());
1699 } else {
1700 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth)
1701 assert(C->failure_is_artificial(), "graph should be schedulable");
1702 C->record_method_not_compilable("late schedule failed: incorrect graph" DEBUG_ONLY(COMMA true));
1703 }
1704 return;
1705 }
1706
1707 if (self->is_memory_writer()) {
1708 // If the LCA of a memory writer is a descendant of its home loop, hoist
1709 // it into a valid placement.
1710 while (LCA->_loop->depth() > early->_loop->depth()) {
1711 LCA = LCA->_idom;
1712 }
1713 assert(LCA != nullptr, "a valid LCA must exist");
1714 verify_memory_writer_placement(LCA, self);
1715 }
1716
1717 // If there is no opportunity to hoist, then we're done.
1718 // In stress mode, try to hoist even the single operations.
1719 bool try_to_hoist = StressGCM || (LCA != early);
1720
1721 // Must clone guys stay next to use; no hoisting allowed.
1722 // Also cannot hoist guys that alter memory or are otherwise not
1723 // allocatable (hoisting can make a value live longer, leading to
1724 // anti and output dependency problems which are normally resolved
1725 // by the register allocator giving everyone a different register).
1726 if (mach != nullptr && must_clone[mach->ideal_Opcode()])
1727 try_to_hoist = false;
1728
1729 Block* late = nullptr;
1730 if (try_to_hoist) {
1731 // Now find the block with the least execution frequency.
1732 // Start at the latest schedule and work up to the earliest schedule
1733 // in the dominator tree. Thus the Node will dominate all its uses.
1734 late = hoist_to_cheaper_block(LCA, early, self);
1735 } else {
1736 // Just use the LCA of the uses.
1737 late = LCA;
1738 }
1739
1740 // Put the node into target block
1741 schedule_node_into_block(self, late);
1742
1743 #ifdef ASSERT
1744 if (self->needs_anti_dependence_check()) {
1745 // since precedence edges are only inserted when we're sure they
1746 // are needed make sure that after placement in a block we don't
1747 // need any new precedence edges.
1748 verify_anti_dependences(late, self);
1749 if (C->failing()) {
1750 return;
1751 }
1752 }
1753 #endif
1754 } // Loop until all nodes have been visited
1755
1756 } // end ScheduleLate
1757
1758 //------------------------------GlobalCodeMotion-------------------------------
1759 void PhaseCFG::global_code_motion() {
1760 ResourceMark rm;
1761
1762 #ifndef PRODUCT
1763 if (trace_opto_pipelining()) {
1764 tty->print("\n---- Start GlobalCodeMotion ----\n");
1765 }
1766 #endif
1767
1768 // Initialize the node to block mapping for things on the proj_list
1769 for (uint i = 0; i < _matcher.number_of_projections(); i++) {
1770 unmap_node_from_block(_matcher.get_projection(i));
1771 }
1772
1773 // Set the basic block for Nodes pinned into blocks
1774 VectorSet visited;
1775 schedule_pinned_nodes(visited);
1776
1777 // Find the earliest Block any instruction can be placed in. Some
1778 // instructions are pinned into Blocks. Unpinned instructions can
1779 // appear in last block in which all their inputs occur.
1780 visited.clear();
1781 Node_Stack stack((C->live_nodes() >> 2) + 16); // pre-grow
1782 if (!schedule_early(visited, stack)) {
1783 // Bailout without retry
1784 assert(C->failure_is_artificial(), "early schedule failed");
1785 C->record_method_not_compilable("early schedule failed" DEBUG_ONLY(COMMA true));
1786 return;
1787 }
1788
1789 // Build Def-Use edges.
1790 // Compute the latency information (via backwards walk) for all the
1791 // instructions in the graph
1792 _node_latency = new GrowableArray<uint>(); // resource_area allocation
1793
1794 if (C->do_scheduling()) {
1795 compute_latencies_backwards(visited, stack);
1796 }
1797
1798 // Now schedule all codes as LATE as possible. This is the LCA in the
1799 // dominator tree of all USES of a value. Pick the block with the least
1800 // loop nesting depth that is lowest in the dominator tree.
1801 // ( visited.clear() called in schedule_late()->Node_Backward_Iterator() )
1802 schedule_late(visited, stack);
1803 if (C->failing()) {
1804 return;
1805 }
1806
1807 #ifndef PRODUCT
1808 if (trace_opto_pipelining()) {
1809 tty->print("\n---- Detect implicit null checks ----\n");
1810 }
1811 #endif
1812
1813 // Detect implicit-null-check opportunities. Basically, find null checks
1814 // with suitable memory ops nearby. Use the memory op to do the null check.
1815 // I can generate a memory op if there is not one nearby.
1816 if (C->is_method_compilation()) {
1817 // By reversing the loop direction we get a very minor gain on mpegaudio.
1818 // Feel free to revert to a forward loop for clarity.
1819 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) {
1820 for (int i = _matcher._null_check_tests.size() - 2; i >= 0; i -= 2) {
1821 Node* proj = _matcher._null_check_tests[i];
1822 Node* val = _matcher._null_check_tests[i + 1];
1823 Block* block = get_block_for_node(proj);
1824 implicit_null_check(block, proj, val, C->allowed_deopt_reasons());
1825 // The implicit_null_check will only perform the transformation
1826 // if the null branch is truly uncommon, *and* it leads to an
1827 // uncommon trap. Combined with the too_many_traps guards
1828 // above, this prevents SEGV storms reported in 6366351,
1829 // by recompiling offending methods without this optimization.
1830 if (C->failing()) {
1831 return;
1832 }
1833 }
1834 }
1835
1836 bool block_size_threshold_ok = false;
1837 intptr_t *recalc_pressure_nodes = nullptr;
1838 if (OptoRegScheduling) {
1839 for (uint i = 0; i < number_of_blocks(); i++) {
1840 Block* block = get_block(i);
1841 if (block->number_of_nodes() > 10) {
1842 block_size_threshold_ok = true;
1843 break;
1844 }
1845 }
1846 }
1847
1848 // Enabling the scheduler for register pressure plus finding blocks of size to schedule for it
1849 // is key to enabling this feature.
1850 PhaseChaitin regalloc(C->unique(), *this, _matcher, true);
1851 ResourceArea live_arena(mtCompiler, Arena::Tag::tag_reglive); // Arena for liveness
1852 ResourceMark rm_live(&live_arena);
1853 PhaseLive live(*this, regalloc._lrg_map.names(), &live_arena, true);
1854 PhaseIFG ifg(&live_arena);
1855 if (OptoRegScheduling && block_size_threshold_ok) {
1856 regalloc.mark_ssa();
1857 Compile::TracePhase tp(_t_computeLive);
1858 rm_live.reset_to_mark(); // Reclaim working storage
1859 IndexSet::reset_memory(C, &live_arena);
1860 uint node_size = regalloc._lrg_map.max_lrg_id();
1861 ifg.init(node_size); // Empty IFG
1862 regalloc.set_ifg(ifg);
1863 regalloc.set_live(live);
1864 regalloc.gather_lrg_masks(false); // Collect LRG masks
1865 live.compute(node_size); // Compute liveness
1866
1867 recalc_pressure_nodes = NEW_RESOURCE_ARRAY(intptr_t, node_size);
1868 for (uint i = 0; i < node_size; i++) {
1869 recalc_pressure_nodes[i] = 0;
1870 }
1871 }
1872 _regalloc = ®alloc;
1873
1874 #ifndef PRODUCT
1875 if (trace_opto_pipelining()) {
1876 tty->print("\n---- Start Local Scheduling ----\n");
1877 }
1878 #endif
1879
1880 // Schedule locally. Right now a simple topological sort.
1881 // Later, do a real latency aware scheduler.
1882 GrowableArray<int> ready_cnt(C->unique(), C->unique(), -1);
1883 visited.reset();
1884 for (uint i = 0; i < number_of_blocks(); i++) {
1885 Block* block = get_block(i);
1886 if (!schedule_local(block, ready_cnt, visited, recalc_pressure_nodes)) {
1887 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
1888 assert(C->failure_is_artificial(), "local schedule failed");
1889 C->record_method_not_compilable("local schedule failed" DEBUG_ONLY(COMMA true));
1890 }
1891 _regalloc = nullptr;
1892 return;
1893 }
1894 }
1895 _regalloc = nullptr;
1896
1897 // If we inserted any instructions between a Call and his CatchNode,
1898 // clone the instructions on all paths below the Catch.
1899 for (uint i = 0; i < number_of_blocks(); i++) {
1900 Block* block = get_block(i);
1901 call_catch_cleanup(block);
1902 if (C->failing()) {
1903 return;
1904 }
1905 }
1906
1907 #ifndef PRODUCT
1908 if (trace_opto_pipelining()) {
1909 tty->print("\n---- After GlobalCodeMotion ----\n");
1910 for (uint i = 0; i < number_of_blocks(); i++) {
1911 Block* block = get_block(i);
1912 block->dump();
1913 }
1914 }
1915 #endif
1916 // Dead.
1917 _node_latency = (GrowableArray<uint> *)((intptr_t)0xdeadbeef);
1918 }
1919
1920 bool PhaseCFG::do_global_code_motion() {
1921
1922 build_dominator_tree();
1923 if (C->failing()) {
1924 return false;
1925 }
1926
1927 NOT_PRODUCT( C->verify_graph_edges(); )
1928
1929 estimate_block_frequency();
1930
1931 global_code_motion();
1932
1933 if (C->failing()) {
1934 return false;
1935 }
1936
1937 return true;
1938 }
1939
1940 //------------------------------Estimate_Block_Frequency-----------------------
1941 // Estimate block frequencies based on IfNode probabilities.
1942 void PhaseCFG::estimate_block_frequency() {
1943
1944 // Force conditional branches leading to uncommon traps to be unlikely,
1945 // not because we get to the uncommon_trap with less relative frequency,
1946 // but because an uncommon_trap typically causes a deopt, so we only get
1947 // there once.
1948 if (C->do_freq_based_layout()) {
1949 Block_List worklist;
1950 Block* root_blk = get_block(0);
1951 for (uint i = 1; i < root_blk->num_preds(); i++) {
1952 Block *pb = get_block_for_node(root_blk->pred(i));
1953 if (pb->has_uncommon_code()) {
1954 worklist.push(pb);
1955 }
1956 }
1957 while (worklist.size() > 0) {
1958 Block* uct = worklist.pop();
1959 if (uct == get_root_block()) {
1960 continue;
1961 }
1962 for (uint i = 1; i < uct->num_preds(); i++) {
1963 Block *pb = get_block_for_node(uct->pred(i));
1964 if (pb->_num_succs == 1) {
1965 worklist.push(pb);
1966 } else if (pb->num_fall_throughs() == 2) {
1967 pb->update_uncommon_branch(uct);
1968 }
1969 }
1970 }
1971 }
1972
1973 // Create the loop tree and calculate loop depth.
1974 _root_loop = create_loop_tree();
1975 _root_loop->compute_loop_depth(0);
1976
1977 // Compute block frequency of each block, relative to a single loop entry.
1978 _root_loop->compute_freq();
1979
1980 // Adjust all frequencies to be relative to a single method entry
1981 _root_loop->_freq = 1.0;
1982 _root_loop->scale_freq();
1983
1984 // Save outmost loop frequency for LRG frequency threshold
1985 _outer_loop_frequency = _root_loop->outer_loop_freq();
1986
1987 // force paths ending at uncommon traps to be infrequent
1988 if (!C->do_freq_based_layout()) {
1989 Block_List worklist;
1990 Block* root_blk = get_block(0);
1991 for (uint i = 1; i < root_blk->num_preds(); i++) {
1992 Block *pb = get_block_for_node(root_blk->pred(i));
1993 if (pb->has_uncommon_code()) {
1994 worklist.push(pb);
1995 }
1996 }
1997 while (worklist.size() > 0) {
1998 Block* uct = worklist.pop();
1999 uct->_freq = PROB_MIN;
2000 for (uint i = 1; i < uct->num_preds(); i++) {
2001 Block *pb = get_block_for_node(uct->pred(i));
2002 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) {
2003 worklist.push(pb);
2004 }
2005 }
2006 }
2007 }
2008
2009 #ifdef ASSERT
2010 for (uint i = 0; i < number_of_blocks(); i++) {
2011 Block* b = get_block(i);
2012 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency");
2013 }
2014 #endif
2015
2016 #ifndef PRODUCT
2017 if (PrintCFGBlockFreq) {
2018 tty->print_cr("CFG Block Frequencies");
2019 _root_loop->dump_tree();
2020 if (Verbose) {
2021 tty->print_cr("PhaseCFG dump");
2022 dump();
2023 tty->print_cr("Node dump");
2024 _root->dump(99999);
2025 }
2026 }
2027 #endif
2028 }
2029
2030 //----------------------------create_loop_tree--------------------------------
2031 // Create a loop tree from the CFG
2032 CFGLoop* PhaseCFG::create_loop_tree() {
2033
2034 #ifdef ASSERT
2035 assert(get_block(0) == get_root_block(), "first block should be root block");
2036 for (uint i = 0; i < number_of_blocks(); i++) {
2037 Block* block = get_block(i);
2038 // Check that _loop field are clear...we could clear them if not.
2039 assert(block->_loop == nullptr, "clear _loop expected");
2040 // Sanity check that the RPO numbering is reflected in the _blocks array.
2041 // It doesn't have to be for the loop tree to be built, but if it is not,
2042 // then the blocks have been reordered since dom graph building...which
2043 // may question the RPO numbering
2044 assert(block->_rpo == i, "unexpected reverse post order number");
2045 }
2046 #endif
2047
2048 int idct = 0;
2049 CFGLoop* root_loop = new CFGLoop(idct++);
2050
2051 Block_List worklist;
2052
2053 // Assign blocks to loops
2054 for(uint i = number_of_blocks() - 1; i > 0; i-- ) { // skip Root block
2055 Block* block = get_block(i);
2056
2057 if (block->head()->is_Loop()) {
2058 Block* loop_head = block;
2059 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
2060 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl);
2061 Block* tail = get_block_for_node(tail_n);
2062
2063 // Defensively filter out Loop nodes for non-single-entry loops.
2064 // For all reasonable loops, the head occurs before the tail in RPO.
2065 if (i <= tail->_rpo) {
2066
2067 // The tail and (recursive) predecessors of the tail
2068 // are made members of a new loop.
2069
2070 assert(worklist.size() == 0, "nonempty worklist");
2071 CFGLoop* nloop = new CFGLoop(idct++);
2072 assert(loop_head->_loop == nullptr, "just checking");
2073 loop_head->_loop = nloop;
2074 // Add to nloop so push_pred() will skip over inner loops
2075 nloop->add_member(loop_head);
2076 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, this);
2077
2078 while (worklist.size() > 0) {
2079 Block* member = worklist.pop();
2080 if (member != loop_head) {
2081 for (uint j = 1; j < member->num_preds(); j++) {
2082 nloop->push_pred(member, j, worklist, this);
2083 }
2084 }
2085 }
2086 }
2087 }
2088 }
2089
2090 // Create a member list for each loop consisting
2091 // of both blocks and (immediate child) loops.
2092 for (uint i = 0; i < number_of_blocks(); i++) {
2093 Block* block = get_block(i);
2094 CFGLoop* lp = block->_loop;
2095 if (lp == nullptr) {
2096 // Not assigned to a loop. Add it to the method's pseudo loop.
2097 block->_loop = root_loop;
2098 lp = root_loop;
2099 }
2100 if (lp == root_loop || block != lp->head()) { // loop heads are already members
2101 lp->add_member(block);
2102 }
2103 if (lp != root_loop) {
2104 if (lp->parent() == nullptr) {
2105 // Not a nested loop. Make it a child of the method's pseudo loop.
2106 root_loop->add_nested_loop(lp);
2107 }
2108 if (block == lp->head()) {
2109 // Add nested loop to member list of parent loop.
2110 lp->parent()->add_member(lp);
2111 }
2112 }
2113 }
2114
2115 return root_loop;
2116 }
2117
2118 //------------------------------push_pred--------------------------------------
2119 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, PhaseCFG* cfg) {
2120 Node* pred_n = blk->pred(i);
2121 Block* pred = cfg->get_block_for_node(pred_n);
2122 CFGLoop *pred_loop = pred->_loop;
2123 if (pred_loop == nullptr) {
2124 // Filter out blocks for non-single-entry loops.
2125 // For all reasonable loops, the head occurs before the tail in RPO.
2126 if (pred->_rpo > head()->_rpo) {
2127 pred->_loop = this;
2128 worklist.push(pred);
2129 }
2130 } else if (pred_loop != this) {
2131 // Nested loop.
2132 while (pred_loop->_parent != nullptr && pred_loop->_parent != this) {
2133 pred_loop = pred_loop->_parent;
2134 }
2135 // Make pred's loop be a child
2136 if (pred_loop->_parent == nullptr) {
2137 add_nested_loop(pred_loop);
2138 // Continue with loop entry predecessor.
2139 Block* pred_head = pred_loop->head();
2140 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
2141 assert(pred_head != head(), "loop head in only one loop");
2142 push_pred(pred_head, LoopNode::EntryControl, worklist, cfg);
2143 } else {
2144 assert(pred_loop->_parent == this && _parent == nullptr, "just checking");
2145 }
2146 }
2147 }
2148
2149 //------------------------------add_nested_loop--------------------------------
2150 // Make cl a child of the current loop in the loop tree.
2151 void CFGLoop::add_nested_loop(CFGLoop* cl) {
2152 assert(_parent == nullptr, "no parent yet");
2153 assert(cl != this, "not my own parent");
2154 cl->_parent = this;
2155 CFGLoop* ch = _child;
2156 if (ch == nullptr) {
2157 _child = cl;
2158 } else {
2159 while (ch->_sibling != nullptr) { ch = ch->_sibling; }
2160 ch->_sibling = cl;
2161 }
2162 }
2163
2164 //------------------------------compute_loop_depth-----------------------------
2165 // Store the loop depth in each CFGLoop object.
2166 // Recursively walk the children to do the same for them.
2167 void CFGLoop::compute_loop_depth(int depth) {
2168 _depth = depth;
2169 CFGLoop* ch = _child;
2170 while (ch != nullptr) {
2171 ch->compute_loop_depth(depth + 1);
2172 ch = ch->_sibling;
2173 }
2174 }
2175
2176 //------------------------------compute_freq-----------------------------------
2177 // Compute the frequency of each block and loop, relative to a single entry
2178 // into the dominating loop head.
2179 void CFGLoop::compute_freq() {
2180 // Bottom up traversal of loop tree (visit inner loops first.)
2181 // Set loop head frequency to 1.0, then transitively
2182 // compute frequency for all successors in the loop,
2183 // as well as for each exit edge. Inner loops are
2184 // treated as single blocks with loop exit targets
2185 // as the successor blocks.
2186
2187 // Nested loops first
2188 CFGLoop* ch = _child;
2189 while (ch != nullptr) {
2190 ch->compute_freq();
2191 ch = ch->_sibling;
2192 }
2193 assert (_members.length() > 0, "no empty loops");
2194 Block* hd = head();
2195 hd->_freq = 1.0;
2196 for (int i = 0; i < _members.length(); i++) {
2197 CFGElement* s = _members.at(i);
2198 double freq = s->_freq;
2199 if (s->is_block()) {
2200 Block* b = s->as_Block();
2201 for (uint j = 0; j < b->_num_succs; j++) {
2202 Block* sb = b->_succs[j];
2203 update_succ_freq(sb, freq * b->succ_prob(j));
2204 }
2205 } else {
2206 CFGLoop* lp = s->as_CFGLoop();
2207 assert(lp->_parent == this, "immediate child");
2208 for (int k = 0; k < lp->_exits.length(); k++) {
2209 Block* eb = lp->_exits.at(k).get_target();
2210 double prob = lp->_exits.at(k).get_prob();
2211 update_succ_freq(eb, freq * prob);
2212 }
2213 }
2214 }
2215
2216 // For all loops other than the outer, "method" loop,
2217 // sum and normalize the exit probability. The "method" loop
2218 // should keep the initial exit probability of 1, so that
2219 // inner blocks do not get erroneously scaled.
2220 if (_depth != 0) {
2221 // Total the exit probabilities for this loop.
2222 double exits_sum = 0.0f;
2223 for (int i = 0; i < _exits.length(); i++) {
2224 exits_sum += _exits.at(i).get_prob();
2225 }
2226
2227 // Normalize the exit probabilities. Until now, the
2228 // probabilities estimate the possibility of exit per
2229 // a single loop iteration; afterward, they estimate
2230 // the probability of exit per loop entry.
2231 for (int i = 0; i < _exits.length(); i++) {
2232 Block* et = _exits.at(i).get_target();
2233 float new_prob = 0.0f;
2234 if (_exits.at(i).get_prob() > 0.0f) {
2235 new_prob = _exits.at(i).get_prob() / exits_sum;
2236 }
2237 BlockProbPair bpp(et, new_prob);
2238 _exits.at_put(i, bpp);
2239 }
2240
2241 // Save the total, but guard against unreasonable probability,
2242 // as the value is used to estimate the loop trip count.
2243 // An infinite trip count would blur relative block
2244 // frequencies.
2245 if (exits_sum > 1.0f) exits_sum = 1.0;
2246 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN;
2247 _exit_prob = exits_sum;
2248 }
2249 }
2250
2251 //------------------------------succ_prob-------------------------------------
2252 // Determine the probability of reaching successor 'i' from the receiver block.
2253 float Block::succ_prob(uint i) {
2254 int eidx = end_idx();
2255 Node *n = get_node(eidx); // Get ending Node
2256
2257 int op = n->Opcode();
2258 if (n->is_Mach()) {
2259 if (n->is_MachNullCheck()) {
2260 // Can only reach here if called after lcm. The original Op_If is gone,
2261 // so we attempt to infer the probability from one or both of the
2262 // successor blocks.
2263 assert(_num_succs == 2, "expecting 2 successors of a null check");
2264 // If either successor has only one predecessor, then the
2265 // probability estimate can be derived using the
2266 // relative frequency of the successor and this block.
2267 if (_succs[i]->num_preds() == 2) {
2268 return _succs[i]->_freq / _freq;
2269 } else if (_succs[1-i]->num_preds() == 2) {
2270 return 1 - (_succs[1-i]->_freq / _freq);
2271 } else {
2272 // Estimate using both successor frequencies
2273 float freq = _succs[i]->_freq;
2274 return freq / (freq + _succs[1-i]->_freq);
2275 }
2276 }
2277 op = n->as_Mach()->ideal_Opcode();
2278 }
2279
2280
2281 // Switch on branch type
2282 switch( op ) {
2283 case Op_CountedLoopEnd:
2284 case Op_If: {
2285 assert (i < 2, "just checking");
2286 // Conditionals pass on only part of their frequency
2287 float prob = n->as_MachIf()->_prob;
2288 assert(prob >= 0.0 && prob <= 1.0, "out of range probability");
2289 // If succ[i] is the FALSE branch, invert path info
2290 if( get_node(i + eidx + 1)->Opcode() == Op_IfFalse ) {
2291 return 1.0f - prob; // not taken
2292 } else {
2293 return prob; // taken
2294 }
2295 }
2296
2297 case Op_Jump:
2298 return n->as_MachJump()->_probs[get_node(i + eidx + 1)->as_JumpProj()->_con];
2299
2300 case Op_Catch: {
2301 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj();
2302 if (ci->_con == CatchProjNode::fall_through_index) {
2303 // Fall-thru path gets the lion's share.
2304 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs;
2305 } else {
2306 // Presume exceptional paths are equally unlikely
2307 return PROB_UNLIKELY_MAG(5);
2308 }
2309 }
2310
2311 case Op_Root:
2312 case Op_Goto:
2313 // Pass frequency straight thru to target
2314 return 1.0f;
2315
2316 case Op_NeverBranch: {
2317 Node* succ = n->as_NeverBranch()->proj_out(0)->unique_ctrl_out();
2318 if (_succs[i]->head() == succ) {
2319 return 1.0f;
2320 }
2321 return 0.0f;
2322 }
2323
2324 case Op_TailCall:
2325 case Op_TailJump:
2326 case Op_ForwardException:
2327 case Op_Return:
2328 case Op_Halt:
2329 case Op_Rethrow:
2330 // Do not push out freq to root block
2331 return 0.0f;
2332
2333 default:
2334 ShouldNotReachHere();
2335 }
2336
2337 return 0.0f;
2338 }
2339
2340 //------------------------------num_fall_throughs-----------------------------
2341 // Return the number of fall-through candidates for a block
2342 int Block::num_fall_throughs() {
2343 int eidx = end_idx();
2344 Node *n = get_node(eidx); // Get ending Node
2345
2346 int op = n->Opcode();
2347 if (n->is_Mach()) {
2348 if (n->is_MachNullCheck()) {
2349 // In theory, either side can fall-thru, for simplicity sake,
2350 // let's say only the false branch can now.
2351 return 1;
2352 }
2353 op = n->as_Mach()->ideal_Opcode();
2354 }
2355
2356 // Switch on branch type
2357 switch( op ) {
2358 case Op_CountedLoopEnd:
2359 case Op_If:
2360 return 2;
2361
2362 case Op_Root:
2363 case Op_Goto:
2364 return 1;
2365
2366 case Op_Catch: {
2367 for (uint i = 0; i < _num_succs; i++) {
2368 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj();
2369 if (ci->_con == CatchProjNode::fall_through_index) {
2370 return 1;
2371 }
2372 }
2373 return 0;
2374 }
2375
2376 case Op_Jump:
2377 case Op_NeverBranch:
2378 case Op_TailCall:
2379 case Op_TailJump:
2380 case Op_ForwardException:
2381 case Op_Return:
2382 case Op_Halt:
2383 case Op_Rethrow:
2384 return 0;
2385
2386 default:
2387 ShouldNotReachHere();
2388 }
2389
2390 return 0;
2391 }
2392
2393 //------------------------------succ_fall_through-----------------------------
2394 // Return true if a specific successor could be fall-through target.
2395 bool Block::succ_fall_through(uint i) {
2396 int eidx = end_idx();
2397 Node *n = get_node(eidx); // Get ending Node
2398
2399 int op = n->Opcode();
2400 if (n->is_Mach()) {
2401 if (n->is_MachNullCheck()) {
2402 // In theory, either side can fall-thru, for simplicity sake,
2403 // let's say only the false branch can now.
2404 return get_node(i + eidx + 1)->Opcode() == Op_IfFalse;
2405 }
2406 op = n->as_Mach()->ideal_Opcode();
2407 }
2408
2409 // Switch on branch type
2410 switch( op ) {
2411 case Op_CountedLoopEnd:
2412 case Op_If:
2413 case Op_Root:
2414 case Op_Goto:
2415 return true;
2416
2417 case Op_Catch: {
2418 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj();
2419 return ci->_con == CatchProjNode::fall_through_index;
2420 }
2421
2422 case Op_Jump:
2423 case Op_NeverBranch:
2424 case Op_TailCall:
2425 case Op_TailJump:
2426 case Op_ForwardException:
2427 case Op_Return:
2428 case Op_Halt:
2429 case Op_Rethrow:
2430 return false;
2431
2432 default:
2433 ShouldNotReachHere();
2434 }
2435
2436 return false;
2437 }
2438
2439 //------------------------------update_uncommon_branch------------------------
2440 // Update the probability of a two-branch to be uncommon
2441 void Block::update_uncommon_branch(Block* ub) {
2442 int eidx = end_idx();
2443 Node *n = get_node(eidx); // Get ending Node
2444
2445 int op = n->as_Mach()->ideal_Opcode();
2446
2447 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If");
2448 assert(num_fall_throughs() == 2, "must be a two way branch block");
2449
2450 // Which successor is ub?
2451 uint s;
2452 for (s = 0; s <_num_succs; s++) {
2453 if (_succs[s] == ub) break;
2454 }
2455 assert(s < 2, "uncommon successor must be found");
2456
2457 // If ub is the true path, make the proability small, else
2458 // ub is the false path, and make the probability large
2459 bool invert = (get_node(s + eidx + 1)->Opcode() == Op_IfFalse);
2460
2461 // Get existing probability
2462 float p = n->as_MachIf()->_prob;
2463
2464 if (invert) p = 1.0 - p;
2465 if (p > PROB_MIN) {
2466 p = PROB_MIN;
2467 }
2468 if (invert) p = 1.0 - p;
2469
2470 n->as_MachIf()->_prob = p;
2471 }
2472
2473 //------------------------------update_succ_freq-------------------------------
2474 // Update the appropriate frequency associated with block 'b', a successor of
2475 // a block in this loop.
2476 void CFGLoop::update_succ_freq(Block* b, double freq) {
2477 if (b->_loop == this) {
2478 if (b == head()) {
2479 // back branch within the loop
2480 // Do nothing now, the loop carried frequency will be
2481 // adjust later in scale_freq().
2482 } else {
2483 // simple branch within the loop
2484 b->_freq += freq;
2485 }
2486 } else if (!in_loop_nest(b)) {
2487 // branch is exit from this loop
2488 BlockProbPair bpp(b, freq);
2489 _exits.append(bpp);
2490 } else {
2491 // branch into nested loop
2492 CFGLoop* ch = b->_loop;
2493 ch->_freq += freq;
2494 }
2495 }
2496
2497 //------------------------------in_loop_nest-----------------------------------
2498 // Determine if block b is in the receiver's loop nest.
2499 bool CFGLoop::in_loop_nest(Block* b) {
2500 int depth = _depth;
2501 CFGLoop* b_loop = b->_loop;
2502 int b_depth = b_loop->_depth;
2503 if (depth == b_depth) {
2504 return true;
2505 }
2506 while (b_depth > depth) {
2507 b_loop = b_loop->_parent;
2508 b_depth = b_loop->_depth;
2509 }
2510 return b_loop == this;
2511 }
2512
2513 //------------------------------scale_freq-------------------------------------
2514 // Scale frequency of loops and blocks by trip counts from outer loops
2515 // Do a top down traversal of loop tree (visit outer loops first.)
2516 void CFGLoop::scale_freq() {
2517 double loop_freq = _freq * trip_count();
2518 _freq = loop_freq;
2519 for (int i = 0; i < _members.length(); i++) {
2520 CFGElement* s = _members.at(i);
2521 double block_freq = s->_freq * loop_freq;
2522 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY)
2523 block_freq = MIN_BLOCK_FREQUENCY;
2524 s->_freq = block_freq;
2525 }
2526 CFGLoop* ch = _child;
2527 while (ch != nullptr) {
2528 ch->scale_freq();
2529 ch = ch->_sibling;
2530 }
2531 }
2532
2533 // Frequency of outer loop
2534 double CFGLoop::outer_loop_freq() const {
2535 if (_child != nullptr) {
2536 return _child->_freq;
2537 }
2538 return _freq;
2539 }
2540
2541 #ifndef PRODUCT
2542 //------------------------------dump_tree--------------------------------------
2543 void CFGLoop::dump_tree() const {
2544 dump();
2545 if (_child != nullptr) _child->dump_tree();
2546 if (_sibling != nullptr) _sibling->dump_tree();
2547 }
2548
2549 //------------------------------dump-------------------------------------------
2550 void CFGLoop::dump() const {
2551 for (int i = 0; i < _depth; i++) tty->print(" ");
2552 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n",
2553 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq);
2554 for (int i = 0; i < _depth; i++) tty->print(" ");
2555 tty->print(" members:");
2556 int k = 0;
2557 for (int i = 0; i < _members.length(); i++) {
2558 if (k++ >= 6) {
2559 tty->print("\n ");
2560 for (int j = 0; j < _depth+1; j++) tty->print(" ");
2561 k = 0;
2562 }
2563 CFGElement *s = _members.at(i);
2564 if (s->is_block()) {
2565 Block *b = s->as_Block();
2566 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq);
2567 } else {
2568 CFGLoop* lp = s->as_CFGLoop();
2569 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq);
2570 }
2571 }
2572 tty->print("\n");
2573 for (int i = 0; i < _depth; i++) tty->print(" ");
2574 tty->print(" exits: ");
2575 k = 0;
2576 for (int i = 0; i < _exits.length(); i++) {
2577 if (k++ >= 7) {
2578 tty->print("\n ");
2579 for (int j = 0; j < _depth+1; j++) tty->print(" ");
2580 k = 0;
2581 }
2582 Block *blk = _exits.at(i).get_target();
2583 double prob = _exits.at(i).get_prob();
2584 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100));
2585 }
2586 tty->print("\n");
2587 }
2588 #endif