1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_gcm.cpp.incl"
31
32 // To avoid float value underflow
33 #define MIN_BLOCK_FREQUENCY 1.e-35f
34
35 //----------------------------schedule_node_into_block-------------------------
36 // Insert node n into block b. Look for projections of n and make sure they
37 // are in b also.
38 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) {
39 // Set basic block of n, Add n to b,
40 _bbs.map(n->_idx, b);
41 b->add_inst(n);
42
43 // After Matching, nearly any old Node may have projections trailing it.
44 // These are usually machine-dependent flags. In any case, they might
45 // float to another block below this one. Move them up.
46 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
47 Node* use = n->fast_out(i);
48 if (use->is_Proj()) {
49 Block* buse = _bbs[use->_idx];
50 if (buse != b) { // In wrong block?
51 if (buse != NULL)
52 buse->find_remove(use); // Remove from wrong block
53 _bbs.map(use->_idx, b); // Re-insert in this block
54 b->add_inst(use);
55 }
56 }
57 }
58 }
59
60 //----------------------------replace_block_proj_ctrl-------------------------
61 // Nodes that have is_block_proj() nodes as their control need to use
62 // the appropriate Region for their actual block as their control since
63 // the projection will be in a predecessor block.
64 void PhaseCFG::replace_block_proj_ctrl( Node *n ) {
65 const Node *in0 = n->in(0);
66 assert(in0 != NULL, "Only control-dependent");
67 const Node *p = in0->is_block_proj();
68 if (p != NULL && p != n) { // Control from a block projection?
69 assert(!n->pinned() || n->is_SafePointScalarObject(), "only SafePointScalarObject pinned node is expected here");
70 // Find trailing Region
71 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block
72 uint j = 0;
73 if (pb->_num_succs != 1) { // More then 1 successor?
74 // Search for successor
75 uint max = pb->_nodes.size();
76 assert( max > 1, "" );
77 uint start = max - pb->_num_succs;
78 // Find which output path belongs to projection
79 for (j = start; j < max; j++) {
80 if( pb->_nodes[j] == in0 )
81 break;
82 }
83 assert( j < max, "must find" );
84 // Change control to match head of successor basic block
85 j -= start;
86 }
87 n->set_req(0, pb->_succs[j]->head());
88 }
89 }
90
91
92 //------------------------------schedule_pinned_nodes--------------------------
93 // Set the basic block for Nodes pinned into blocks
94 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) {
95 // Allocate node stack of size C->unique()+8 to avoid frequent realloc
96 GrowableArray <Node *> spstack(C->unique()+8);
97 spstack.push(_root);
98 while ( spstack.is_nonempty() ) {
99 Node *n = spstack.pop();
100 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited
101 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down!
102 assert( n->in(0), "pinned Node must have Control" );
103 // Before setting block replace block_proj control edge
104 replace_block_proj_ctrl(n);
105 Node *input = n->in(0);
106 while( !input->is_block_start() )
107 input = input->in(0);
108 Block *b = _bbs[input->_idx]; // Basic block of controlling input
109 schedule_node_into_block(n, b);
110 }
111 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs
112 if( n->in(i) != NULL )
113 spstack.push(n->in(i));
114 }
115 }
116 }
117 }
118
119 #ifdef ASSERT
120 // Assert that new input b2 is dominated by all previous inputs.
121 // Check this by by seeing that it is dominated by b1, the deepest
122 // input observed until b2.
123 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) {
124 if (b1 == NULL) return;
125 assert(b1->_dom_depth < b2->_dom_depth, "sanity");
126 Block* tmp = b2;
127 while (tmp != b1 && tmp != NULL) {
128 tmp = tmp->_idom;
129 }
130 if (tmp != b1) {
131 // Detected an unschedulable graph. Print some nice stuff and die.
132 tty->print_cr("!!! Unschedulable graph !!!");
133 for (uint j=0; j<n->len(); j++) { // For all inputs
134 Node* inn = n->in(j); // Get input
135 if (inn == NULL) continue; // Ignore NULL, missing inputs
136 Block* inb = bbs[inn->_idx];
137 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order,
138 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth);
139 inn->dump();
140 }
141 tty->print("Failing node: ");
142 n->dump();
143 assert(false, "unscheduable graph");
144 }
145 }
146 #endif
147
148 static Block* find_deepest_input(Node* n, Block_Array &bbs) {
149 // Find the last input dominated by all other inputs.
150 Block* deepb = NULL; // Deepest block so far
151 int deepb_dom_depth = 0;
152 for (uint k = 0; k < n->len(); k++) { // For all inputs
153 Node* inn = n->in(k); // Get input
154 if (inn == NULL) continue; // Ignore NULL, missing inputs
155 Block* inb = bbs[inn->_idx];
156 assert(inb != NULL, "must already have scheduled this input");
157 if (deepb_dom_depth < (int) inb->_dom_depth) {
158 // The new inb must be dominated by the previous deepb.
159 // The various inputs must be linearly ordered in the dom
160 // tree, or else there will not be a unique deepest block.
161 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs));
162 deepb = inb; // Save deepest block
163 deepb_dom_depth = deepb->_dom_depth;
164 }
165 }
166 assert(deepb != NULL, "must be at least one input to n");
167 return deepb;
168 }
169
170
171 //------------------------------schedule_early---------------------------------
172 // Find the earliest Block any instruction can be placed in. Some instructions
173 // are pinned into Blocks. Unpinned instructions can appear in last block in
174 // which all their inputs occur.
175 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) {
176 // Allocate stack with enough space to avoid frequent realloc
177 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats
178 // roots.push(_root); _root will be processed among C->top() inputs
179 roots.push(C->top());
180 visited.set(C->top()->_idx);
181
182 while (roots.size() != 0) {
183 // Use local variables nstack_top_n & nstack_top_i to cache values
184 // on stack's top.
185 Node *nstack_top_n = roots.pop();
186 uint nstack_top_i = 0;
187 //while_nstack_nonempty:
188 while (true) {
189 // Get parent node and next input's index from stack's top.
190 Node *n = nstack_top_n;
191 uint i = nstack_top_i;
192
193 if (i == 0) {
194 // Fixup some control. Constants without control get attached
195 // to root and nodes that use is_block_proj() nodes should be attached
196 // to the region that starts their block.
197 const Node *in0 = n->in(0);
198 if (in0 != NULL) { // Control-dependent?
199 replace_block_proj_ctrl(n);
200 } else { // n->in(0) == NULL
201 if (n->req() == 1) { // This guy is a constant with NO inputs?
202 n->set_req(0, _root);
203 }
204 }
205 }
206
207 // First, visit all inputs and force them to get a block. If an
208 // input is already in a block we quit following inputs (to avoid
209 // cycles). Instead we put that Node on a worklist to be handled
210 // later (since IT'S inputs may not have a block yet).
211 bool done = true; // Assume all n's inputs will be processed
212 while (i < n->len()) { // For all inputs
213 Node *in = n->in(i); // Get input
214 ++i;
215 if (in == NULL) continue; // Ignore NULL, missing inputs
216 int is_visited = visited.test_set(in->_idx);
217 if (!_bbs.lookup(in->_idx)) { // Missing block selection?
218 if (is_visited) {
219 // assert( !visited.test(in->_idx), "did not schedule early" );
220 return false;
221 }
222 nstack.push(n, i); // Save parent node and next input's index.
223 nstack_top_n = in; // Process current input now.
224 nstack_top_i = 0;
225 done = false; // Not all n's inputs processed.
226 break; // continue while_nstack_nonempty;
227 } else if (!is_visited) { // Input not yet visited?
228 roots.push(in); // Visit this guy later, using worklist
229 }
230 }
231 if (done) {
232 // All of n's inputs have been processed, complete post-processing.
233
234 // Some instructions are pinned into a block. These include Region,
235 // Phi, Start, Return, and other control-dependent instructions and
236 // any projections which depend on them.
237 if (!n->pinned()) {
238 // Set earliest legal block.
239 _bbs.map(n->_idx, find_deepest_input(n, _bbs));
240 } else {
241 assert(_bbs[n->_idx] == _bbs[n->in(0)->_idx], "Pinned Node should be at the same block as its control edge");
242 }
243
244 if (nstack.is_empty()) {
245 // Finished all nodes on stack.
246 // Process next node on the worklist 'roots'.
247 break;
248 }
249 // Get saved parent node and next input's index.
250 nstack_top_n = nstack.node();
251 nstack_top_i = nstack.index();
252 nstack.pop();
253 } // if (done)
254 } // while (true)
255 } // while (roots.size() != 0)
256 return true;
257 }
258
259 //------------------------------dom_lca----------------------------------------
260 // Find least common ancestor in dominator tree
261 // LCA is a current notion of LCA, to be raised above 'this'.
262 // As a convenient boundary condition, return 'this' if LCA is NULL.
263 // Find the LCA of those two nodes.
264 Block* Block::dom_lca(Block* LCA) {
265 if (LCA == NULL || LCA == this) return this;
266
267 Block* anc = this;
268 while (anc->_dom_depth > LCA->_dom_depth)
269 anc = anc->_idom; // Walk up till anc is as high as LCA
270
271 while (LCA->_dom_depth > anc->_dom_depth)
272 LCA = LCA->_idom; // Walk up till LCA is as high as anc
273
274 while (LCA != anc) { // Walk both up till they are the same
275 LCA = LCA->_idom;
276 anc = anc->_idom;
277 }
278
279 return LCA;
280 }
281
282 //--------------------------raise_LCA_above_use--------------------------------
283 // We are placing a definition, and have been given a def->use edge.
284 // The definition must dominate the use, so move the LCA upward in the
285 // dominator tree to dominate the use. If the use is a phi, adjust
286 // the LCA only with the phi input paths which actually use this def.
287 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) {
288 Block* buse = bbs[use->_idx];
289 if (buse == NULL) return LCA; // Unused killing Projs have no use block
290 if (!use->is_Phi()) return buse->dom_lca(LCA);
291 uint pmax = use->req(); // Number of Phi inputs
292 // Why does not this loop just break after finding the matching input to
293 // the Phi? Well...it's like this. I do not have true def-use/use-def
294 // chains. Means I cannot distinguish, from the def-use direction, which
295 // of many use-defs lead from the same use to the same def. That is, this
296 // Phi might have several uses of the same def. Each use appears in a
297 // different predecessor block. But when I enter here, I cannot distinguish
298 // which use-def edge I should find the predecessor block for. So I find
299 // them all. Means I do a little extra work if a Phi uses the same value
300 // more than once.
301 for (uint j=1; j<pmax; j++) { // For all inputs
302 if (use->in(j) == def) { // Found matching input?
303 Block* pred = bbs[buse->pred(j)->_idx];
304 LCA = pred->dom_lca(LCA);
305 }
306 }
307 return LCA;
308 }
309
310 //----------------------------raise_LCA_above_marks----------------------------
311 // Return a new LCA that dominates LCA and any of its marked predecessors.
312 // Search all my parents up to 'early' (exclusive), looking for predecessors
313 // which are marked with the given index. Return the LCA (in the dom tree)
314 // of all marked blocks. If there are none marked, return the original
315 // LCA.
316 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark,
317 Block* early, Block_Array &bbs) {
318 Block_List worklist;
319 worklist.push(LCA);
320 while (worklist.size() > 0) {
321 Block* mid = worklist.pop();
322 if (mid == early) continue; // stop searching here
323
324 // Test and set the visited bit.
325 if (mid->raise_LCA_visited() == mark) continue; // already visited
326
327 // Don't process the current LCA, otherwise the search may terminate early
328 if (mid != LCA && mid->raise_LCA_mark() == mark) {
329 // Raise the LCA.
330 LCA = mid->dom_lca(LCA);
331 if (LCA == early) break; // stop searching everywhere
332 assert(early->dominates(LCA), "early is high enough");
333 // Resume searching at that point, skipping intermediate levels.
334 worklist.push(LCA);
335 if (LCA == mid)
336 continue; // Don't mark as visited to avoid early termination.
337 } else {
338 // Keep searching through this block's predecessors.
339 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) {
340 Block* mid_parent = bbs[ mid->pred(j)->_idx ];
341 worklist.push(mid_parent);
342 }
343 }
344 mid->set_raise_LCA_visited(mark);
345 }
346 return LCA;
347 }
348
349 //--------------------------memory_early_block--------------------------------
350 // This is a variation of find_deepest_input, the heart of schedule_early.
351 // Find the "early" block for a load, if we considered only memory and
352 // address inputs, that is, if other data inputs were ignored.
353 //
354 // Because a subset of edges are considered, the resulting block will
355 // be earlier (at a shallower dom_depth) than the true schedule_early
356 // point of the node. We compute this earlier block as a more permissive
357 // site for anti-dependency insertion, but only if subsume_loads is enabled.
358 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) {
359 Node* base;
360 Node* index;
361 Node* store = load->in(MemNode::Memory);
362 load->as_Mach()->memory_inputs(base, index);
363
364 assert(base != NodeSentinel && index != NodeSentinel,
365 "unexpected base/index inputs");
366
367 Node* mem_inputs[4];
368 int mem_inputs_length = 0;
369 if (base != NULL) mem_inputs[mem_inputs_length++] = base;
370 if (index != NULL) mem_inputs[mem_inputs_length++] = index;
371 if (store != NULL) mem_inputs[mem_inputs_length++] = store;
372
373 // In the comparision below, add one to account for the control input,
374 // which may be null, but always takes up a spot in the in array.
375 if (mem_inputs_length + 1 < (int) load->req()) {
376 // This "load" has more inputs than just the memory, base and index inputs.
377 // For purposes of checking anti-dependences, we need to start
378 // from the early block of only the address portion of the instruction,
379 // and ignore other blocks that may have factored into the wider
380 // schedule_early calculation.
381 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0);
382
383 Block* deepb = NULL; // Deepest block so far
384 int deepb_dom_depth = 0;
385 for (int i = 0; i < mem_inputs_length; i++) {
386 Block* inb = bbs[mem_inputs[i]->_idx];
387 if (deepb_dom_depth < (int) inb->_dom_depth) {
388 // The new inb must be dominated by the previous deepb.
389 // The various inputs must be linearly ordered in the dom
390 // tree, or else there will not be a unique deepest block.
391 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs));
392 deepb = inb; // Save deepest block
393 deepb_dom_depth = deepb->_dom_depth;
394 }
395 }
396 early = deepb;
397 }
398
399 return early;
400 }
401
402 //--------------------------insert_anti_dependences---------------------------
403 // A load may need to witness memory that nearby stores can overwrite.
404 // For each nearby store, either insert an "anti-dependence" edge
405 // from the load to the store, or else move LCA upward to force the
406 // load to (eventually) be scheduled in a block above the store.
407 //
408 // Do not add edges to stores on distinct control-flow paths;
409 // only add edges to stores which might interfere.
410 //
411 // Return the (updated) LCA. There will not be any possibly interfering
412 // store between the load's "early block" and the updated LCA.
413 // Any stores in the updated LCA will have new precedence edges
414 // back to the load. The caller is expected to schedule the load
415 // in the LCA, in which case the precedence edges will make LCM
416 // preserve anti-dependences. The caller may also hoist the load
417 // above the LCA, if it is not the early block.
418 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) {
419 assert(load->needs_anti_dependence_check(), "must be a load of some sort");
420 assert(LCA != NULL, "");
421 DEBUG_ONLY(Block* LCA_orig = LCA);
422
423 // Compute the alias index. Loads and stores with different alias indices
424 // do not need anti-dependence edges.
425 uint load_alias_idx = C->get_alias_index(load->adr_type());
426 #ifdef ASSERT
427 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 &&
428 (PrintOpto || VerifyAliases ||
429 PrintMiscellaneous && (WizardMode || Verbose))) {
430 // Load nodes should not consume all of memory.
431 // Reporting a bottom type indicates a bug in adlc.
432 // If some particular type of node validly consumes all of memory,
433 // sharpen the preceding "if" to exclude it, so we can catch bugs here.
434 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory.");
435 load->dump(2);
436 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, "");
437 }
438 #endif
439 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp),
440 "String compare is only known 'load' that does not conflict with any stores");
441 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrEquals),
442 "String equals is a 'load' that does not conflict with any stores");
443 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOf),
444 "String indexOf is a 'load' that does not conflict with any stores");
445 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_AryEq),
446 "Arrays equals is a 'load' that do not conflict with any stores");
447
448 if (!C->alias_type(load_alias_idx)->is_rewritable()) {
449 // It is impossible to spoil this load by putting stores before it,
450 // because we know that the stores will never update the value
451 // which 'load' must witness.
452 return LCA;
453 }
454
455 node_idx_t load_index = load->_idx;
456
457 // Note the earliest legal placement of 'load', as determined by
458 // by the unique point in the dom tree where all memory effects
459 // and other inputs are first available. (Computed by schedule_early.)
460 // For normal loads, 'early' is the shallowest place (dom graph wise)
461 // to look for anti-deps between this load and any store.
462 Block* early = _bbs[load_index];
463
464 // If we are subsuming loads, compute an "early" block that only considers
465 // memory or address inputs. This block may be different than the
466 // schedule_early block in that it could be at an even shallower depth in the
467 // dominator tree, and allow for a broader discovery of anti-dependences.
468 if (C->subsume_loads()) {
469 early = memory_early_block(load, early, _bbs);
470 }
471
472 ResourceArea *area = Thread::current()->resource_area();
473 Node_List worklist_mem(area); // prior memory state to store
474 Node_List worklist_store(area); // possible-def to explore
475 Node_List worklist_visited(area); // visited mergemem nodes
476 Node_List non_early_stores(area); // all relevant stores outside of early
477 bool must_raise_LCA = false;
478
479 #ifdef TRACK_PHI_INPUTS
480 // %%% This extra checking fails because MergeMem nodes are not GVNed.
481 // Provide "phi_inputs" to check if every input to a PhiNode is from the
482 // original memory state. This indicates a PhiNode for which should not
483 // prevent the load from sinking. For such a block, set_raise_LCA_mark
484 // may be overly conservative.
485 // Mechanism: count inputs seen for each Phi encountered in worklist_store.
486 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0));
487 #endif
488
489 // 'load' uses some memory state; look for users of the same state.
490 // Recurse through MergeMem nodes to the stores that use them.
491
492 // Each of these stores is a possible definition of memory
493 // that 'load' needs to use. We need to force 'load'
494 // to occur before each such store. When the store is in
495 // the same block as 'load', we insert an anti-dependence
496 // edge load->store.
497
498 // The relevant stores "nearby" the load consist of a tree rooted
499 // at initial_mem, with internal nodes of type MergeMem.
500 // Therefore, the branches visited by the worklist are of this form:
501 // initial_mem -> (MergeMem ->)* store
502 // The anti-dependence constraints apply only to the fringe of this tree.
503
504 Node* initial_mem = load->in(MemNode::Memory);
505 worklist_store.push(initial_mem);
506 worklist_visited.push(initial_mem);
507 worklist_mem.push(NULL);
508 while (worklist_store.size() > 0) {
509 // Examine a nearby store to see if it might interfere with our load.
510 Node* mem = worklist_mem.pop();
511 Node* store = worklist_store.pop();
512 uint op = store->Opcode();
513
514 // MergeMems do not directly have anti-deps.
515 // Treat them as internal nodes in a forward tree of memory states,
516 // the leaves of which are each a 'possible-def'.
517 if (store == initial_mem // root (exclusive) of tree we are searching
518 || op == Op_MergeMem // internal node of tree we are searching
519 ) {
520 mem = store; // It's not a possibly interfering store.
521 if (store == initial_mem)
522 initial_mem = NULL; // only process initial memory once
523
524 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
525 store = mem->fast_out(i);
526 if (store->is_MergeMem()) {
527 // Be sure we don't get into combinatorial problems.
528 // (Allow phis to be repeated; they can merge two relevant states.)
529 uint j = worklist_visited.size();
530 for (; j > 0; j--) {
531 if (worklist_visited.at(j-1) == store) break;
532 }
533 if (j > 0) continue; // already on work list; do not repeat
534 worklist_visited.push(store);
535 }
536 worklist_mem.push(mem);
537 worklist_store.push(store);
538 }
539 continue;
540 }
541
542 if (op == Op_MachProj || op == Op_Catch) continue;
543 if (store->needs_anti_dependence_check()) continue; // not really a store
544
545 // Compute the alias index. Loads and stores with different alias
546 // indices do not need anti-dependence edges. Wide MemBar's are
547 // anti-dependent on everything (except immutable memories).
548 const TypePtr* adr_type = store->adr_type();
549 if (!C->can_alias(adr_type, load_alias_idx)) continue;
550
551 // Most slow-path runtime calls do NOT modify Java memory, but
552 // they can block and so write Raw memory.
553 if (store->is_Mach()) {
554 MachNode* mstore = store->as_Mach();
555 if (load_alias_idx != Compile::AliasIdxRaw) {
556 // Check for call into the runtime using the Java calling
557 // convention (and from there into a wrapper); it has no
558 // _method. Can't do this optimization for Native calls because
559 // they CAN write to Java memory.
560 if (mstore->ideal_Opcode() == Op_CallStaticJava) {
561 assert(mstore->is_MachSafePoint(), "");
562 MachSafePointNode* ms = (MachSafePointNode*) mstore;
563 assert(ms->is_MachCallJava(), "");
564 MachCallJavaNode* mcj = (MachCallJavaNode*) ms;
565 if (mcj->_method == NULL) {
566 // These runtime calls do not write to Java visible memory
567 // (other than Raw) and so do not require anti-dependence edges.
568 continue;
569 }
570 }
571 // Same for SafePoints: they read/write Raw but only read otherwise.
572 // This is basically a workaround for SafePoints only defining control
573 // instead of control + memory.
574 if (mstore->ideal_Opcode() == Op_SafePoint)
575 continue;
576 } else {
577 // Some raw memory, such as the load of "top" at an allocation,
578 // can be control dependent on the previous safepoint. See
579 // comments in GraphKit::allocate_heap() about control input.
580 // Inserting an anti-dep between such a safepoint and a use
581 // creates a cycle, and will cause a subsequent failure in
582 // local scheduling. (BugId 4919904)
583 // (%%% How can a control input be a safepoint and not a projection??)
584 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore)
585 continue;
586 }
587 }
588
589 // Identify a block that the current load must be above,
590 // or else observe that 'store' is all the way up in the
591 // earliest legal block for 'load'. In the latter case,
592 // immediately insert an anti-dependence edge.
593 Block* store_block = _bbs[store->_idx];
594 assert(store_block != NULL, "unused killing projections skipped above");
595
596 if (store->is_Phi()) {
597 // 'load' uses memory which is one (or more) of the Phi's inputs.
598 // It must be scheduled not before the Phi, but rather before
599 // each of the relevant Phi inputs.
600 //
601 // Instead of finding the LCA of all inputs to a Phi that match 'mem',
602 // we mark each corresponding predecessor block and do a combined
603 // hoisting operation later (raise_LCA_above_marks).
604 //
605 // Do not assert(store_block != early, "Phi merging memory after access")
606 // PhiNode may be at start of block 'early' with backedge to 'early'
607 DEBUG_ONLY(bool found_match = false);
608 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) {
609 if (store->in(j) == mem) { // Found matching input?
610 DEBUG_ONLY(found_match = true);
611 Block* pred_block = _bbs[store_block->pred(j)->_idx];
612 if (pred_block != early) {
613 // If any predecessor of the Phi matches the load's "early block",
614 // we do not need a precedence edge between the Phi and 'load'
615 // since the load will be forced into a block preceding the Phi.
616 pred_block->set_raise_LCA_mark(load_index);
617 assert(!LCA_orig->dominates(pred_block) ||
618 early->dominates(pred_block), "early is high enough");
619 must_raise_LCA = true;
620 }
621 }
622 }
623 assert(found_match, "no worklist bug");
624 #ifdef TRACK_PHI_INPUTS
625 #ifdef ASSERT
626 // This assert asks about correct handling of PhiNodes, which may not
627 // have all input edges directly from 'mem'. See BugId 4621264
628 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1;
629 // Increment by exactly one even if there are multiple copies of 'mem'
630 // coming into the phi, because we will run this block several times
631 // if there are several copies of 'mem'. (That's how DU iterators work.)
632 phi_inputs.at_put(store->_idx, num_mem_inputs);
633 assert(PhiNode::Input + num_mem_inputs < store->req(),
634 "Expect at least one phi input will not be from original memory state");
635 #endif //ASSERT
636 #endif //TRACK_PHI_INPUTS
637 } else if (store_block != early) {
638 // 'store' is between the current LCA and earliest possible block.
639 // Label its block, and decide later on how to raise the LCA
640 // to include the effect on LCA of this store.
641 // If this store's block gets chosen as the raised LCA, we
642 // will find him on the non_early_stores list and stick him
643 // with a precedence edge.
644 // (But, don't bother if LCA is already raised all the way.)
645 if (LCA != early) {
646 store_block->set_raise_LCA_mark(load_index);
647 must_raise_LCA = true;
648 non_early_stores.push(store);
649 }
650 } else {
651 // Found a possibly-interfering store in the load's 'early' block.
652 // This means 'load' cannot sink at all in the dominator tree.
653 // Add an anti-dep edge, and squeeze 'load' into the highest block.
654 assert(store != load->in(0), "dependence cycle found");
655 if (verify) {
656 assert(store->find_edge(load) != -1, "missing precedence edge");
657 } else {
658 store->add_prec(load);
659 }
660 LCA = early;
661 // This turns off the process of gathering non_early_stores.
662 }
663 }
664 // (Worklist is now empty; all nearby stores have been visited.)
665
666 // Finished if 'load' must be scheduled in its 'early' block.
667 // If we found any stores there, they have already been given
668 // precedence edges.
669 if (LCA == early) return LCA;
670
671 // We get here only if there are no possibly-interfering stores
672 // in the load's 'early' block. Move LCA up above all predecessors
673 // which contain stores we have noted.
674 //
675 // The raised LCA block can be a home to such interfering stores,
676 // but its predecessors must not contain any such stores.
677 //
678 // The raised LCA will be a lower bound for placing the load,
679 // preventing the load from sinking past any block containing
680 // a store that may invalidate the memory state required by 'load'.
681 if (must_raise_LCA)
682 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs);
683 if (LCA == early) return LCA;
684
685 // Insert anti-dependence edges from 'load' to each store
686 // in the non-early LCA block.
687 // Mine the non_early_stores list for such stores.
688 if (LCA->raise_LCA_mark() == load_index) {
689 while (non_early_stores.size() > 0) {
690 Node* store = non_early_stores.pop();
691 Block* store_block = _bbs[store->_idx];
692 if (store_block == LCA) {
693 // add anti_dependence from store to load in its own block
694 assert(store != load->in(0), "dependence cycle found");
695 if (verify) {
696 assert(store->find_edge(load) != -1, "missing precedence edge");
697 } else {
698 store->add_prec(load);
699 }
700 } else {
701 assert(store_block->raise_LCA_mark() == load_index, "block was marked");
702 // Any other stores we found must be either inside the new LCA
703 // or else outside the original LCA. In the latter case, they
704 // did not interfere with any use of 'load'.
705 assert(LCA->dominates(store_block)
706 || !LCA_orig->dominates(store_block), "no stray stores");
707 }
708 }
709 }
710
711 // Return the highest block containing stores; any stores
712 // within that block have been given anti-dependence edges.
713 return LCA;
714 }
715
716 // This class is used to iterate backwards over the nodes in the graph.
717
718 class Node_Backward_Iterator {
719
720 private:
721 Node_Backward_Iterator();
722
723 public:
724 // Constructor for the iterator
725 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs);
726
727 // Postincrement operator to iterate over the nodes
728 Node *next();
729
730 private:
731 VectorSet &_visited;
732 Node_List &_stack;
733 Block_Array &_bbs;
734 };
735
736 // Constructor for the Node_Backward_Iterator
737 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs )
738 : _visited(visited), _stack(stack), _bbs(bbs) {
739 // The stack should contain exactly the root
740 stack.clear();
741 stack.push(root);
742
743 // Clear the visited bits
744 visited.Clear();
745 }
746
747 // Iterator for the Node_Backward_Iterator
748 Node *Node_Backward_Iterator::next() {
749
750 // If the _stack is empty, then just return NULL: finished.
751 if ( !_stack.size() )
752 return NULL;
753
754 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been
755 // made stateless, so I do not need to record the index 'i' on my _stack.
756 // Instead I visit all users each time, scanning for unvisited users.
757 // I visit unvisited not-anti-dependence users first, then anti-dependent
758 // children next.
759 Node *self = _stack.pop();
760
761 // I cycle here when I am entering a deeper level of recursion.
762 // The key variable 'self' was set prior to jumping here.
763 while( 1 ) {
764
765 _visited.set(self->_idx);
766
767 // Now schedule all uses as late as possible.
768 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx;
769 uint src_rpo = _bbs[src]->_rpo;
770
771 // Schedule all nodes in a post-order visit
772 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any
773
774 // Scan for unvisited nodes
775 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
776 // For all uses, schedule late
777 Node* n = self->fast_out(i); // Use
778
779 // Skip already visited children
780 if ( _visited.test(n->_idx) )
781 continue;
782
783 // do not traverse backward control edges
784 Node *use = n->is_Proj() ? n->in(0) : n;
785 uint use_rpo = _bbs[use->_idx]->_rpo;
786
787 if ( use_rpo < src_rpo )
788 continue;
789
790 // Phi nodes always precede uses in a basic block
791 if ( use_rpo == src_rpo && use->is_Phi() )
792 continue;
793
794 unvisited = n; // Found unvisited
795
796 // Check for possible-anti-dependent
797 if( !n->needs_anti_dependence_check() )
798 break; // Not visited, not anti-dep; schedule it NOW
799 }
800
801 // Did I find an unvisited not-anti-dependent Node?
802 if ( !unvisited )
803 break; // All done with children; post-visit 'self'
804
805 // Visit the unvisited Node. Contains the obvious push to
806 // indicate I'm entering a deeper level of recursion. I push the
807 // old state onto the _stack and set a new state and loop (recurse).
808 _stack.push(self);
809 self = unvisited;
810 } // End recursion loop
811
812 return self;
813 }
814
815 //------------------------------ComputeLatenciesBackwards----------------------
816 // Compute the latency of all the instructions.
817 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) {
818 #ifndef PRODUCT
819 if (trace_opto_pipelining())
820 tty->print("\n#---- ComputeLatenciesBackwards ----\n");
821 #endif
822
823 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
824 Node *n;
825
826 // Walk over all the nodes from last to first
827 while (n = iter.next()) {
828 // Set the latency for the definitions of this instruction
829 partial_latency_of_defs(n);
830 }
831 } // end ComputeLatenciesBackwards
832
833 //------------------------------partial_latency_of_defs------------------------
834 // Compute the latency impact of this node on all defs. This computes
835 // a number that increases as we approach the beginning of the routine.
836 void PhaseCFG::partial_latency_of_defs(Node *n) {
837 // Set the latency for this instruction
838 #ifndef PRODUCT
839 if (trace_opto_pipelining()) {
840 tty->print("# latency_to_inputs: node_latency[%d] = %d for node",
841 n->_idx, _node_latency.at_grow(n->_idx));
842 dump();
843 }
844 #endif
845
846 if (n->is_Proj())
847 n = n->in(0);
848
849 if (n->is_Root())
850 return;
851
852 uint nlen = n->len();
853 uint use_latency = _node_latency.at_grow(n->_idx);
854 uint use_pre_order = _bbs[n->_idx]->_pre_order;
855
856 for ( uint j=0; j<nlen; j++ ) {
857 Node *def = n->in(j);
858
859 if (!def || def == n)
860 continue;
861
862 // Walk backwards thru projections
863 if (def->is_Proj())
864 def = def->in(0);
865
866 #ifndef PRODUCT
867 if (trace_opto_pipelining()) {
868 tty->print("# in(%2d): ", j);
869 def->dump();
870 }
871 #endif
872
873 // If the defining block is not known, assume it is ok
874 Block *def_block = _bbs[def->_idx];
875 uint def_pre_order = def_block ? def_block->_pre_order : 0;
876
877 if ( (use_pre_order < def_pre_order) ||
878 (use_pre_order == def_pre_order && n->is_Phi()) )
879 continue;
880
881 uint delta_latency = n->latency(j);
882 uint current_latency = delta_latency + use_latency;
883
884 if (_node_latency.at_grow(def->_idx) < current_latency) {
885 _node_latency.at_put_grow(def->_idx, current_latency);
886 }
887
888 #ifndef PRODUCT
889 if (trace_opto_pipelining()) {
890 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d",
891 use_latency, j, delta_latency, current_latency, def->_idx,
892 _node_latency.at_grow(def->_idx));
893 }
894 #endif
895 }
896 }
897
898 //------------------------------latency_from_use-------------------------------
899 // Compute the latency of a specific use
900 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) {
901 // If self-reference, return no latency
902 if (use == n || use->is_Root())
903 return 0;
904
905 uint def_pre_order = _bbs[def->_idx]->_pre_order;
906 uint latency = 0;
907
908 // If the use is not a projection, then it is simple...
909 if (!use->is_Proj()) {
910 #ifndef PRODUCT
911 if (trace_opto_pipelining()) {
912 tty->print("# out(): ");
913 use->dump();
914 }
915 #endif
916
917 uint use_pre_order = _bbs[use->_idx]->_pre_order;
918
919 if (use_pre_order < def_pre_order)
920 return 0;
921
922 if (use_pre_order == def_pre_order && use->is_Phi())
923 return 0;
924
925 uint nlen = use->len();
926 uint nl = _node_latency.at_grow(use->_idx);
927
928 for ( uint j=0; j<nlen; j++ ) {
929 if (use->in(j) == n) {
930 // Change this if we want local latencies
931 uint ul = use->latency(j);
932 uint l = ul + nl;
933 if (latency < l) latency = l;
934 #ifndef PRODUCT
935 if (trace_opto_pipelining()) {
936 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d",
937 nl, j, ul, l, latency);
938 }
939 #endif
940 }
941 }
942 } else {
943 // This is a projection, just grab the latency of the use(s)
944 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) {
945 uint l = latency_from_use(use, def, use->fast_out(j));
946 if (latency < l) latency = l;
947 }
948 }
949
950 return latency;
951 }
952
953 //------------------------------latency_from_uses------------------------------
954 // Compute the latency of this instruction relative to all of it's uses.
955 // This computes a number that increases as we approach the beginning of the
956 // routine.
957 void PhaseCFG::latency_from_uses(Node *n) {
958 // Set the latency for this instruction
959 #ifndef PRODUCT
960 if (trace_opto_pipelining()) {
961 tty->print("# latency_from_outputs: node_latency[%d] = %d for node",
962 n->_idx, _node_latency.at_grow(n->_idx));
963 dump();
964 }
965 #endif
966 uint latency=0;
967 const Node *def = n->is_Proj() ? n->in(0): n;
968
969 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
970 uint l = latency_from_use(n, def, n->fast_out(i));
971
972 if (latency < l) latency = l;
973 }
974
975 _node_latency.at_put_grow(n->_idx, latency);
976 }
977
978 //------------------------------hoist_to_cheaper_block-------------------------
979 // Pick a block for node self, between early and LCA, that is a cheaper
980 // alternative to LCA.
981 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) {
982 const double delta = 1+PROB_UNLIKELY_MAG(4);
983 Block* least = LCA;
984 double least_freq = least->_freq;
985 uint target = _node_latency.at_grow(self->_idx);
986 uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx);
987 uint end_latency = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx);
988 bool in_latency = (target <= start_latency);
989 const Block* root_block = _bbs[_root->_idx];
990
991 // Turn off latency scheduling if scheduling is just plain off
992 if (!C->do_scheduling())
993 in_latency = true;
994
995 // Do not hoist (to cover latency) instructions which target a
996 // single register. Hoisting stretches the live range of the
997 // single register and may force spilling.
998 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
999 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty())
1000 in_latency = true;
1001
1002 #ifndef PRODUCT
1003 if (trace_opto_pipelining()) {
1004 tty->print("# Find cheaper block for latency %d: ",
1005 _node_latency.at_grow(self->_idx));
1006 self->dump();
1007 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1008 LCA->_pre_order,
1009 LCA->_nodes[0]->_idx,
1010 start_latency,
1011 LCA->_nodes[LCA->end_idx()]->_idx,
1012 end_latency,
1013 least_freq);
1014 }
1015 #endif
1016
1017 // Walk up the dominator tree from LCA (Lowest common ancestor) to
1018 // the earliest legal location. Capture the least execution frequency.
1019 while (LCA != early) {
1020 LCA = LCA->_idom; // Follow up the dominator tree
1021
1022 if (LCA == NULL) {
1023 // Bailout without retry
1024 C->record_method_not_compilable("late schedule failed: LCA == NULL");
1025 return least;
1026 }
1027
1028 // Don't hoist machine instructions to the root basic block
1029 if (mach && LCA == root_block)
1030 break;
1031
1032 uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx);
1033 uint end_idx = LCA->end_idx();
1034 uint end_lat = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx);
1035 double LCA_freq = LCA->_freq;
1036 #ifndef PRODUCT
1037 if (trace_opto_pipelining()) {
1038 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1039 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq);
1040 }
1041 #endif
1042 if (LCA_freq < least_freq || // Better Frequency
1043 ( !in_latency && // No block containing latency
1044 LCA_freq < least_freq * delta && // No worse frequency
1045 target >= end_lat && // within latency range
1046 !self->is_iteratively_computed() ) // But don't hoist IV increments
1047 // because they may end up above other uses of their phi forcing
1048 // their result register to be different from their input.
1049 ) {
1050 least = LCA; // Found cheaper block
1051 least_freq = LCA_freq;
1052 start_latency = start_lat;
1053 end_latency = end_lat;
1054 if (target <= start_lat)
1055 in_latency = true;
1056 }
1057 }
1058
1059 #ifndef PRODUCT
1060 if (trace_opto_pipelining()) {
1061 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g",
1062 least->_pre_order, start_latency, least_freq);
1063 }
1064 #endif
1065
1066 // See if the latency needs to be updated
1067 if (target < end_latency) {
1068 #ifndef PRODUCT
1069 if (trace_opto_pipelining()) {
1070 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency);
1071 }
1072 #endif
1073 _node_latency.at_put_grow(self->_idx, end_latency);
1074 partial_latency_of_defs(self);
1075 }
1076
1077 return least;
1078 }
1079
1080
1081 //------------------------------schedule_late-----------------------------------
1082 // Now schedule all codes as LATE as possible. This is the LCA in the
1083 // dominator tree of all USES of a value. Pick the block with the least
1084 // loop nesting depth that is lowest in the dominator tree.
1085 extern const char must_clone[];
1086 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) {
1087 #ifndef PRODUCT
1088 if (trace_opto_pipelining())
1089 tty->print("\n#---- schedule_late ----\n");
1090 #endif
1091
1092 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
1093 Node *self;
1094
1095 // Walk over all the nodes from last to first
1096 while (self = iter.next()) {
1097 Block* early = _bbs[self->_idx]; // Earliest legal placement
1098
1099 if (self->is_top()) {
1100 // Top node goes in bb #2 with other constants.
1101 // It must be special-cased, because it has no out edges.
1102 early->add_inst(self);
1103 continue;
1104 }
1105
1106 // No uses, just terminate
1107 if (self->outcnt() == 0) {
1108 assert(self->Opcode() == Op_MachProj, "sanity");
1109 continue; // Must be a dead machine projection
1110 }
1111
1112 // If node is pinned in the block, then no scheduling can be done.
1113 if( self->pinned() ) // Pinned in block?
1114 continue;
1115
1116 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
1117 if (mach) {
1118 switch (mach->ideal_Opcode()) {
1119 case Op_CreateEx:
1120 // Don't move exception creation
1121 early->add_inst(self);
1122 continue;
1123 break;
1124 case Op_CheckCastPP:
1125 // Don't move CheckCastPP nodes away from their input, if the input
1126 // is a rawptr (5071820).
1127 Node *def = self->in(1);
1128 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) {
1129 early->add_inst(self);
1130 continue;
1131 }
1132 break;
1133 }
1134 }
1135
1136 // Gather LCA of all uses
1137 Block *LCA = NULL;
1138 {
1139 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
1140 // For all uses, find LCA
1141 Node* use = self->fast_out(i);
1142 LCA = raise_LCA_above_use(LCA, use, self, _bbs);
1143 }
1144 } // (Hide defs of imax, i from rest of block.)
1145
1146 // Place temps in the block of their use. This isn't a
1147 // requirement for correctness but it reduces useless
1148 // interference between temps and other nodes.
1149 if (mach != NULL && mach->is_MachTemp()) {
1150 _bbs.map(self->_idx, LCA);
1151 LCA->add_inst(self);
1152 continue;
1153 }
1154
1155 // Check if 'self' could be anti-dependent on memory
1156 if (self->needs_anti_dependence_check()) {
1157 // Hoist LCA above possible-defs and insert anti-dependences to
1158 // defs in new LCA block.
1159 LCA = insert_anti_dependences(LCA, self);
1160 }
1161
1162 if (early->_dom_depth > LCA->_dom_depth) {
1163 // Somehow the LCA has moved above the earliest legal point.
1164 // (One way this can happen is via memory_early_block.)
1165 if (C->subsume_loads() == true && !C->failing()) {
1166 // Retry with subsume_loads == false
1167 // If this is the first failure, the sentinel string will "stick"
1168 // to the Compile object, and the C2Compiler will see it and retry.
1169 C->record_failure(C2Compiler::retry_no_subsuming_loads());
1170 } else {
1171 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth)
1172 C->record_method_not_compilable("late schedule failed: incorrect graph");
1173 }
1174 return;
1175 }
1176
1177 // If there is no opportunity to hoist, then we're done.
1178 bool try_to_hoist = (LCA != early);
1179
1180 // Must clone guys stay next to use; no hoisting allowed.
1181 // Also cannot hoist guys that alter memory or are otherwise not
1182 // allocatable (hoisting can make a value live longer, leading to
1183 // anti and output dependency problems which are normally resolved
1184 // by the register allocator giving everyone a different register).
1185 if (mach != NULL && must_clone[mach->ideal_Opcode()])
1186 try_to_hoist = false;
1187
1188 Block* late = NULL;
1189 if (try_to_hoist) {
1190 // Now find the block with the least execution frequency.
1191 // Start at the latest schedule and work up to the earliest schedule
1192 // in the dominator tree. Thus the Node will dominate all its uses.
1193 late = hoist_to_cheaper_block(LCA, early, self);
1194 } else {
1195 // Just use the LCA of the uses.
1196 late = LCA;
1197 }
1198
1199 // Put the node into target block
1200 schedule_node_into_block(self, late);
1201
1202 #ifdef ASSERT
1203 if (self->needs_anti_dependence_check()) {
1204 // since precedence edges are only inserted when we're sure they
1205 // are needed make sure that after placement in a block we don't
1206 // need any new precedence edges.
1207 verify_anti_dependences(late, self);
1208 }
1209 #endif
1210 } // Loop until all nodes have been visited
1211
1212 } // end ScheduleLate
1213
1214 //------------------------------GlobalCodeMotion-------------------------------
1215 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) {
1216 ResourceMark rm;
1217
1218 #ifndef PRODUCT
1219 if (trace_opto_pipelining()) {
1220 tty->print("\n---- Start GlobalCodeMotion ----\n");
1221 }
1222 #endif
1223
1224 // Initialize the bbs.map for things on the proj_list
1225 uint i;
1226 for( i=0; i < proj_list.size(); i++ )
1227 _bbs.map(proj_list[i]->_idx, NULL);
1228
1229 // Set the basic block for Nodes pinned into blocks
1230 Arena *a = Thread::current()->resource_area();
1231 VectorSet visited(a);
1232 schedule_pinned_nodes( visited );
1233
1234 // Find the earliest Block any instruction can be placed in. Some
1235 // instructions are pinned into Blocks. Unpinned instructions can
1236 // appear in last block in which all their inputs occur.
1237 visited.Clear();
1238 Node_List stack(a);
1239 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list
1240 if (!schedule_early(visited, stack)) {
1241 // Bailout without retry
1242 C->record_method_not_compilable("early schedule failed");
1243 return;
1244 }
1245
1246 // Build Def-Use edges.
1247 proj_list.push(_root); // Add real root as another root
1248 proj_list.pop();
1249
1250 // Compute the latency information (via backwards walk) for all the
1251 // instructions in the graph
1252 GrowableArray<uint> node_latency;
1253 _node_latency = node_latency;
1254
1255 if( C->do_scheduling() )
1256 ComputeLatenciesBackwards(visited, stack);
1257
1258 // Now schedule all codes as LATE as possible. This is the LCA in the
1259 // dominator tree of all USES of a value. Pick the block with the least
1260 // loop nesting depth that is lowest in the dominator tree.
1261 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() )
1262 schedule_late(visited, stack);
1263 if( C->failing() ) {
1264 // schedule_late fails only when graph is incorrect.
1265 assert(!VerifyGraphEdges, "verification should have failed");
1266 return;
1267 }
1268
1269 unique = C->unique();
1270
1271 #ifndef PRODUCT
1272 if (trace_opto_pipelining()) {
1273 tty->print("\n---- Detect implicit null checks ----\n");
1274 }
1275 #endif
1276
1277 // Detect implicit-null-check opportunities. Basically, find NULL checks
1278 // with suitable memory ops nearby. Use the memory op to do the NULL check.
1279 // I can generate a memory op if there is not one nearby.
1280 if (C->is_method_compilation()) {
1281 // Don't do it for natives, adapters, or runtime stubs
1282 int allowed_reasons = 0;
1283 // ...and don't do it when there have been too many traps, globally.
1284 for (int reason = (int)Deoptimization::Reason_none+1;
1285 reason < Compile::trapHistLength; reason++) {
1286 assert(reason < BitsPerInt, "recode bit map");
1287 if (!C->too_many_traps((Deoptimization::DeoptReason) reason))
1288 allowed_reasons |= nth_bit(reason);
1289 }
1290 // By reversing the loop direction we get a very minor gain on mpegaudio.
1291 // Feel free to revert to a forward loop for clarity.
1292 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) {
1293 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) {
1294 Node *proj = matcher._null_check_tests[i ];
1295 Node *val = matcher._null_check_tests[i+1];
1296 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons);
1297 // The implicit_null_check will only perform the transformation
1298 // if the null branch is truly uncommon, *and* it leads to an
1299 // uncommon trap. Combined with the too_many_traps guards
1300 // above, this prevents SEGV storms reported in 6366351,
1301 // by recompiling offending methods without this optimization.
1302 }
1303 }
1304
1305 #ifndef PRODUCT
1306 if (trace_opto_pipelining()) {
1307 tty->print("\n---- Start Local Scheduling ----\n");
1308 }
1309 #endif
1310
1311 // Schedule locally. Right now a simple topological sort.
1312 // Later, do a real latency aware scheduler.
1313 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique());
1314 memset( ready_cnt, -1, C->unique() * sizeof(int) );
1315 visited.Clear();
1316 for (i = 0; i < _num_blocks; i++) {
1317 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) {
1318 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
1319 C->record_method_not_compilable("local schedule failed");
1320 }
1321 return;
1322 }
1323 }
1324
1325 // If we inserted any instructions between a Call and his CatchNode,
1326 // clone the instructions on all paths below the Catch.
1327 for( i=0; i < _num_blocks; i++ )
1328 _blocks[i]->call_catch_cleanup(_bbs);
1329
1330 #ifndef PRODUCT
1331 if (trace_opto_pipelining()) {
1332 tty->print("\n---- After GlobalCodeMotion ----\n");
1333 for (uint i = 0; i < _num_blocks; i++) {
1334 _blocks[i]->dump();
1335 }
1336 }
1337 #endif
1338 }
1339
1340
1341 //------------------------------Estimate_Block_Frequency-----------------------
1342 // Estimate block frequencies based on IfNode probabilities.
1343 void PhaseCFG::Estimate_Block_Frequency() {
1344
1345 // Force conditional branches leading to uncommon traps to be unlikely,
1346 // not because we get to the uncommon_trap with less relative frequency,
1347 // but because an uncommon_trap typically causes a deopt, so we only get
1348 // there once.
1349 if (C->do_freq_based_layout()) {
1350 Block_List worklist;
1351 Block* root_blk = _blocks[0];
1352 for (uint i = 1; i < root_blk->num_preds(); i++) {
1353 Block *pb = _bbs[root_blk->pred(i)->_idx];
1354 if (pb->has_uncommon_code()) {
1355 worklist.push(pb);
1356 }
1357 }
1358 while (worklist.size() > 0) {
1359 Block* uct = worklist.pop();
1360 if (uct == _broot) continue;
1361 for (uint i = 1; i < uct->num_preds(); i++) {
1362 Block *pb = _bbs[uct->pred(i)->_idx];
1363 if (pb->_num_succs == 1) {
1364 worklist.push(pb);
1365 } else if (pb->num_fall_throughs() == 2) {
1366 pb->update_uncommon_branch(uct);
1367 }
1368 }
1369 }
1370 }
1371
1372 // Create the loop tree and calculate loop depth.
1373 _root_loop = create_loop_tree();
1374 _root_loop->compute_loop_depth(0);
1375
1376 // Compute block frequency of each block, relative to a single loop entry.
1377 _root_loop->compute_freq();
1378
1379 // Adjust all frequencies to be relative to a single method entry
1380 _root_loop->_freq = 1.0;
1381 _root_loop->scale_freq();
1382
1383 // Save outmost loop frequency for LRG frequency threshold
1384 _outer_loop_freq = _root_loop->outer_loop_freq();
1385
1386 // force paths ending at uncommon traps to be infrequent
1387 if (!C->do_freq_based_layout()) {
1388 Block_List worklist;
1389 Block* root_blk = _blocks[0];
1390 for (uint i = 1; i < root_blk->num_preds(); i++) {
1391 Block *pb = _bbs[root_blk->pred(i)->_idx];
1392 if (pb->has_uncommon_code()) {
1393 worklist.push(pb);
1394 }
1395 }
1396 while (worklist.size() > 0) {
1397 Block* uct = worklist.pop();
1398 uct->_freq = PROB_MIN;
1399 for (uint i = 1; i < uct->num_preds(); i++) {
1400 Block *pb = _bbs[uct->pred(i)->_idx];
1401 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) {
1402 worklist.push(pb);
1403 }
1404 }
1405 }
1406 }
1407
1408 #ifdef ASSERT
1409 for (uint i = 0; i < _num_blocks; i++ ) {
1410 Block *b = _blocks[i];
1411 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency");
1412 }
1413 #endif
1414
1415 #ifndef PRODUCT
1416 if (PrintCFGBlockFreq) {
1417 tty->print_cr("CFG Block Frequencies");
1418 _root_loop->dump_tree();
1419 if (Verbose) {
1420 tty->print_cr("PhaseCFG dump");
1421 dump();
1422 tty->print_cr("Node dump");
1423 _root->dump(99999);
1424 }
1425 }
1426 #endif
1427 }
1428
1429 //----------------------------create_loop_tree--------------------------------
1430 // Create a loop tree from the CFG
1431 CFGLoop* PhaseCFG::create_loop_tree() {
1432
1433 #ifdef ASSERT
1434 assert( _blocks[0] == _broot, "" );
1435 for (uint i = 0; i < _num_blocks; i++ ) {
1436 Block *b = _blocks[i];
1437 // Check that _loop field are clear...we could clear them if not.
1438 assert(b->_loop == NULL, "clear _loop expected");
1439 // Sanity check that the RPO numbering is reflected in the _blocks array.
1440 // It doesn't have to be for the loop tree to be built, but if it is not,
1441 // then the blocks have been reordered since dom graph building...which
1442 // may question the RPO numbering
1443 assert(b->_rpo == i, "unexpected reverse post order number");
1444 }
1445 #endif
1446
1447 int idct = 0;
1448 CFGLoop* root_loop = new CFGLoop(idct++);
1449
1450 Block_List worklist;
1451
1452 // Assign blocks to loops
1453 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block
1454 Block *b = _blocks[i];
1455
1456 if (b->head()->is_Loop()) {
1457 Block* loop_head = b;
1458 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1459 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl);
1460 Block* tail = _bbs[tail_n->_idx];
1461
1462 // Defensively filter out Loop nodes for non-single-entry loops.
1463 // For all reasonable loops, the head occurs before the tail in RPO.
1464 if (i <= tail->_rpo) {
1465
1466 // The tail and (recursive) predecessors of the tail
1467 // are made members of a new loop.
1468
1469 assert(worklist.size() == 0, "nonempty worklist");
1470 CFGLoop* nloop = new CFGLoop(idct++);
1471 assert(loop_head->_loop == NULL, "just checking");
1472 loop_head->_loop = nloop;
1473 // Add to nloop so push_pred() will skip over inner loops
1474 nloop->add_member(loop_head);
1475 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs);
1476
1477 while (worklist.size() > 0) {
1478 Block* member = worklist.pop();
1479 if (member != loop_head) {
1480 for (uint j = 1; j < member->num_preds(); j++) {
1481 nloop->push_pred(member, j, worklist, _bbs);
1482 }
1483 }
1484 }
1485 }
1486 }
1487 }
1488
1489 // Create a member list for each loop consisting
1490 // of both blocks and (immediate child) loops.
1491 for (uint i = 0; i < _num_blocks; i++) {
1492 Block *b = _blocks[i];
1493 CFGLoop* lp = b->_loop;
1494 if (lp == NULL) {
1495 // Not assigned to a loop. Add it to the method's pseudo loop.
1496 b->_loop = root_loop;
1497 lp = root_loop;
1498 }
1499 if (lp == root_loop || b != lp->head()) { // loop heads are already members
1500 lp->add_member(b);
1501 }
1502 if (lp != root_loop) {
1503 if (lp->parent() == NULL) {
1504 // Not a nested loop. Make it a child of the method's pseudo loop.
1505 root_loop->add_nested_loop(lp);
1506 }
1507 if (b == lp->head()) {
1508 // Add nested loop to member list of parent loop.
1509 lp->parent()->add_member(lp);
1510 }
1511 }
1512 }
1513
1514 return root_loop;
1515 }
1516
1517 //------------------------------push_pred--------------------------------------
1518 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) {
1519 Node* pred_n = blk->pred(i);
1520 Block* pred = node_to_blk[pred_n->_idx];
1521 CFGLoop *pred_loop = pred->_loop;
1522 if (pred_loop == NULL) {
1523 // Filter out blocks for non-single-entry loops.
1524 // For all reasonable loops, the head occurs before the tail in RPO.
1525 if (pred->_rpo > head()->_rpo) {
1526 pred->_loop = this;
1527 worklist.push(pred);
1528 }
1529 } else if (pred_loop != this) {
1530 // Nested loop.
1531 while (pred_loop->_parent != NULL && pred_loop->_parent != this) {
1532 pred_loop = pred_loop->_parent;
1533 }
1534 // Make pred's loop be a child
1535 if (pred_loop->_parent == NULL) {
1536 add_nested_loop(pred_loop);
1537 // Continue with loop entry predecessor.
1538 Block* pred_head = pred_loop->head();
1539 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1540 assert(pred_head != head(), "loop head in only one loop");
1541 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk);
1542 } else {
1543 assert(pred_loop->_parent == this && _parent == NULL, "just checking");
1544 }
1545 }
1546 }
1547
1548 //------------------------------add_nested_loop--------------------------------
1549 // Make cl a child of the current loop in the loop tree.
1550 void CFGLoop::add_nested_loop(CFGLoop* cl) {
1551 assert(_parent == NULL, "no parent yet");
1552 assert(cl != this, "not my own parent");
1553 cl->_parent = this;
1554 CFGLoop* ch = _child;
1555 if (ch == NULL) {
1556 _child = cl;
1557 } else {
1558 while (ch->_sibling != NULL) { ch = ch->_sibling; }
1559 ch->_sibling = cl;
1560 }
1561 }
1562
1563 //------------------------------compute_loop_depth-----------------------------
1564 // Store the loop depth in each CFGLoop object.
1565 // Recursively walk the children to do the same for them.
1566 void CFGLoop::compute_loop_depth(int depth) {
1567 _depth = depth;
1568 CFGLoop* ch = _child;
1569 while (ch != NULL) {
1570 ch->compute_loop_depth(depth + 1);
1571 ch = ch->_sibling;
1572 }
1573 }
1574
1575 //------------------------------compute_freq-----------------------------------
1576 // Compute the frequency of each block and loop, relative to a single entry
1577 // into the dominating loop head.
1578 void CFGLoop::compute_freq() {
1579 // Bottom up traversal of loop tree (visit inner loops first.)
1580 // Set loop head frequency to 1.0, then transitively
1581 // compute frequency for all successors in the loop,
1582 // as well as for each exit edge. Inner loops are
1583 // treated as single blocks with loop exit targets
1584 // as the successor blocks.
1585
1586 // Nested loops first
1587 CFGLoop* ch = _child;
1588 while (ch != NULL) {
1589 ch->compute_freq();
1590 ch = ch->_sibling;
1591 }
1592 assert (_members.length() > 0, "no empty loops");
1593 Block* hd = head();
1594 hd->_freq = 1.0f;
1595 for (int i = 0; i < _members.length(); i++) {
1596 CFGElement* s = _members.at(i);
1597 float freq = s->_freq;
1598 if (s->is_block()) {
1599 Block* b = s->as_Block();
1600 for (uint j = 0; j < b->_num_succs; j++) {
1601 Block* sb = b->_succs[j];
1602 update_succ_freq(sb, freq * b->succ_prob(j));
1603 }
1604 } else {
1605 CFGLoop* lp = s->as_CFGLoop();
1606 assert(lp->_parent == this, "immediate child");
1607 for (int k = 0; k < lp->_exits.length(); k++) {
1608 Block* eb = lp->_exits.at(k).get_target();
1609 float prob = lp->_exits.at(k).get_prob();
1610 update_succ_freq(eb, freq * prob);
1611 }
1612 }
1613 }
1614
1615 // For all loops other than the outer, "method" loop,
1616 // sum and normalize the exit probability. The "method" loop
1617 // should keep the initial exit probability of 1, so that
1618 // inner blocks do not get erroneously scaled.
1619 if (_depth != 0) {
1620 // Total the exit probabilities for this loop.
1621 float exits_sum = 0.0f;
1622 for (int i = 0; i < _exits.length(); i++) {
1623 exits_sum += _exits.at(i).get_prob();
1624 }
1625
1626 // Normalize the exit probabilities. Until now, the
1627 // probabilities estimate the possibility of exit per
1628 // a single loop iteration; afterward, they estimate
1629 // the probability of exit per loop entry.
1630 for (int i = 0; i < _exits.length(); i++) {
1631 Block* et = _exits.at(i).get_target();
1632 float new_prob = 0.0f;
1633 if (_exits.at(i).get_prob() > 0.0f) {
1634 new_prob = _exits.at(i).get_prob() / exits_sum;
1635 }
1636 BlockProbPair bpp(et, new_prob);
1637 _exits.at_put(i, bpp);
1638 }
1639
1640 // Save the total, but guard against unreasonable probability,
1641 // as the value is used to estimate the loop trip count.
1642 // An infinite trip count would blur relative block
1643 // frequencies.
1644 if (exits_sum > 1.0f) exits_sum = 1.0;
1645 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN;
1646 _exit_prob = exits_sum;
1647 }
1648 }
1649
1650 //------------------------------succ_prob-------------------------------------
1651 // Determine the probability of reaching successor 'i' from the receiver block.
1652 float Block::succ_prob(uint i) {
1653 int eidx = end_idx();
1654 Node *n = _nodes[eidx]; // Get ending Node
1655
1656 int op = n->Opcode();
1657 if (n->is_Mach()) {
1658 if (n->is_MachNullCheck()) {
1659 // Can only reach here if called after lcm. The original Op_If is gone,
1660 // so we attempt to infer the probability from one or both of the
1661 // successor blocks.
1662 assert(_num_succs == 2, "expecting 2 successors of a null check");
1663 // If either successor has only one predecessor, then the
1664 // probability estimate can be derived using the
1665 // relative frequency of the successor and this block.
1666 if (_succs[i]->num_preds() == 2) {
1667 return _succs[i]->_freq / _freq;
1668 } else if (_succs[1-i]->num_preds() == 2) {
1669 return 1 - (_succs[1-i]->_freq / _freq);
1670 } else {
1671 // Estimate using both successor frequencies
1672 float freq = _succs[i]->_freq;
1673 return freq / (freq + _succs[1-i]->_freq);
1674 }
1675 }
1676 op = n->as_Mach()->ideal_Opcode();
1677 }
1678
1679
1680 // Switch on branch type
1681 switch( op ) {
1682 case Op_CountedLoopEnd:
1683 case Op_If: {
1684 assert (i < 2, "just checking");
1685 // Conditionals pass on only part of their frequency
1686 float prob = n->as_MachIf()->_prob;
1687 assert(prob >= 0.0 && prob <= 1.0, "out of range probability");
1688 // If succ[i] is the FALSE branch, invert path info
1689 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) {
1690 return 1.0f - prob; // not taken
1691 } else {
1692 return prob; // taken
1693 }
1694 }
1695
1696 case Op_Jump:
1697 // Divide the frequency between all successors evenly
1698 return 1.0f/_num_succs;
1699
1700 case Op_Catch: {
1701 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1702 if (ci->_con == CatchProjNode::fall_through_index) {
1703 // Fall-thru path gets the lion's share.
1704 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs;
1705 } else {
1706 // Presume exceptional paths are equally unlikely
1707 return PROB_UNLIKELY_MAG(5);
1708 }
1709 }
1710
1711 case Op_Root:
1712 case Op_Goto:
1713 // Pass frequency straight thru to target
1714 return 1.0f;
1715
1716 case Op_NeverBranch:
1717 return 0.0f;
1718
1719 case Op_TailCall:
1720 case Op_TailJump:
1721 case Op_Return:
1722 case Op_Halt:
1723 case Op_Rethrow:
1724 // Do not push out freq to root block
1725 return 0.0f;
1726
1727 default:
1728 ShouldNotReachHere();
1729 }
1730
1731 return 0.0f;
1732 }
1733
1734 //------------------------------num_fall_throughs-----------------------------
1735 // Return the number of fall-through candidates for a block
1736 int Block::num_fall_throughs() {
1737 int eidx = end_idx();
1738 Node *n = _nodes[eidx]; // Get ending Node
1739
1740 int op = n->Opcode();
1741 if (n->is_Mach()) {
1742 if (n->is_MachNullCheck()) {
1743 // In theory, either side can fall-thru, for simplicity sake,
1744 // let's say only the false branch can now.
1745 return 1;
1746 }
1747 op = n->as_Mach()->ideal_Opcode();
1748 }
1749
1750 // Switch on branch type
1751 switch( op ) {
1752 case Op_CountedLoopEnd:
1753 case Op_If:
1754 return 2;
1755
1756 case Op_Root:
1757 case Op_Goto:
1758 return 1;
1759
1760 case Op_Catch: {
1761 for (uint i = 0; i < _num_succs; i++) {
1762 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1763 if (ci->_con == CatchProjNode::fall_through_index) {
1764 return 1;
1765 }
1766 }
1767 return 0;
1768 }
1769
1770 case Op_Jump:
1771 case Op_NeverBranch:
1772 case Op_TailCall:
1773 case Op_TailJump:
1774 case Op_Return:
1775 case Op_Halt:
1776 case Op_Rethrow:
1777 return 0;
1778
1779 default:
1780 ShouldNotReachHere();
1781 }
1782
1783 return 0;
1784 }
1785
1786 //------------------------------succ_fall_through-----------------------------
1787 // Return true if a specific successor could be fall-through target.
1788 bool Block::succ_fall_through(uint i) {
1789 int eidx = end_idx();
1790 Node *n = _nodes[eidx]; // Get ending Node
1791
1792 int op = n->Opcode();
1793 if (n->is_Mach()) {
1794 if (n->is_MachNullCheck()) {
1795 // In theory, either side can fall-thru, for simplicity sake,
1796 // let's say only the false branch can now.
1797 return _nodes[i + eidx + 1]->Opcode() == Op_IfFalse;
1798 }
1799 op = n->as_Mach()->ideal_Opcode();
1800 }
1801
1802 // Switch on branch type
1803 switch( op ) {
1804 case Op_CountedLoopEnd:
1805 case Op_If:
1806 case Op_Root:
1807 case Op_Goto:
1808 return true;
1809
1810 case Op_Catch: {
1811 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1812 return ci->_con == CatchProjNode::fall_through_index;
1813 }
1814
1815 case Op_Jump:
1816 case Op_NeverBranch:
1817 case Op_TailCall:
1818 case Op_TailJump:
1819 case Op_Return:
1820 case Op_Halt:
1821 case Op_Rethrow:
1822 return false;
1823
1824 default:
1825 ShouldNotReachHere();
1826 }
1827
1828 return false;
1829 }
1830
1831 //------------------------------update_uncommon_branch------------------------
1832 // Update the probability of a two-branch to be uncommon
1833 void Block::update_uncommon_branch(Block* ub) {
1834 int eidx = end_idx();
1835 Node *n = _nodes[eidx]; // Get ending Node
1836
1837 int op = n->as_Mach()->ideal_Opcode();
1838
1839 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If");
1840 assert(num_fall_throughs() == 2, "must be a two way branch block");
1841
1842 // Which successor is ub?
1843 uint s;
1844 for (s = 0; s <_num_succs; s++) {
1845 if (_succs[s] == ub) break;
1846 }
1847 assert(s < 2, "uncommon successor must be found");
1848
1849 // If ub is the true path, make the proability small, else
1850 // ub is the false path, and make the probability large
1851 bool invert = (_nodes[s + eidx + 1]->Opcode() == Op_IfFalse);
1852
1853 // Get existing probability
1854 float p = n->as_MachIf()->_prob;
1855
1856 if (invert) p = 1.0 - p;
1857 if (p > PROB_MIN) {
1858 p = PROB_MIN;
1859 }
1860 if (invert) p = 1.0 - p;
1861
1862 n->as_MachIf()->_prob = p;
1863 }
1864
1865 //------------------------------update_succ_freq-------------------------------
1866 // Update the appropriate frequency associated with block 'b', a successor of
1867 // a block in this loop.
1868 void CFGLoop::update_succ_freq(Block* b, float freq) {
1869 if (b->_loop == this) {
1870 if (b == head()) {
1871 // back branch within the loop
1872 // Do nothing now, the loop carried frequency will be
1873 // adjust later in scale_freq().
1874 } else {
1875 // simple branch within the loop
1876 b->_freq += freq;
1877 }
1878 } else if (!in_loop_nest(b)) {
1879 // branch is exit from this loop
1880 BlockProbPair bpp(b, freq);
1881 _exits.append(bpp);
1882 } else {
1883 // branch into nested loop
1884 CFGLoop* ch = b->_loop;
1885 ch->_freq += freq;
1886 }
1887 }
1888
1889 //------------------------------in_loop_nest-----------------------------------
1890 // Determine if block b is in the receiver's loop nest.
1891 bool CFGLoop::in_loop_nest(Block* b) {
1892 int depth = _depth;
1893 CFGLoop* b_loop = b->_loop;
1894 int b_depth = b_loop->_depth;
1895 if (depth == b_depth) {
1896 return true;
1897 }
1898 while (b_depth > depth) {
1899 b_loop = b_loop->_parent;
1900 b_depth = b_loop->_depth;
1901 }
1902 return b_loop == this;
1903 }
1904
1905 //------------------------------scale_freq-------------------------------------
1906 // Scale frequency of loops and blocks by trip counts from outer loops
1907 // Do a top down traversal of loop tree (visit outer loops first.)
1908 void CFGLoop::scale_freq() {
1909 float loop_freq = _freq * trip_count();
1910 _freq = loop_freq;
1911 for (int i = 0; i < _members.length(); i++) {
1912 CFGElement* s = _members.at(i);
1913 float block_freq = s->_freq * loop_freq;
1914 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY)
1915 block_freq = MIN_BLOCK_FREQUENCY;
1916 s->_freq = block_freq;
1917 }
1918 CFGLoop* ch = _child;
1919 while (ch != NULL) {
1920 ch->scale_freq();
1921 ch = ch->_sibling;
1922 }
1923 }
1924
1925 // Frequency of outer loop
1926 float CFGLoop::outer_loop_freq() const {
1927 if (_child != NULL) {
1928 return _child->_freq;
1929 }
1930 return _freq;
1931 }
1932
1933 #ifndef PRODUCT
1934 //------------------------------dump_tree--------------------------------------
1935 void CFGLoop::dump_tree() const {
1936 dump();
1937 if (_child != NULL) _child->dump_tree();
1938 if (_sibling != NULL) _sibling->dump_tree();
1939 }
1940
1941 //------------------------------dump-------------------------------------------
1942 void CFGLoop::dump() const {
1943 for (int i = 0; i < _depth; i++) tty->print(" ");
1944 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n",
1945 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq);
1946 for (int i = 0; i < _depth; i++) tty->print(" ");
1947 tty->print(" members:", _id);
1948 int k = 0;
1949 for (int i = 0; i < _members.length(); i++) {
1950 if (k++ >= 6) {
1951 tty->print("\n ");
1952 for (int j = 0; j < _depth+1; j++) tty->print(" ");
1953 k = 0;
1954 }
1955 CFGElement *s = _members.at(i);
1956 if (s->is_block()) {
1957 Block *b = s->as_Block();
1958 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq);
1959 } else {
1960 CFGLoop* lp = s->as_CFGLoop();
1961 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq);
1962 }
1963 }
1964 tty->print("\n");
1965 for (int i = 0; i < _depth; i++) tty->print(" ");
1966 tty->print(" exits: ");
1967 k = 0;
1968 for (int i = 0; i < _exits.length(); i++) {
1969 if (k++ >= 7) {
1970 tty->print("\n ");
1971 for (int j = 0; j < _depth+1; j++) tty->print(" ");
1972 k = 0;
1973 }
1974 Block *blk = _exits.at(i).get_target();
1975 float prob = _exits.at(i).get_prob();
1976 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100));
1977 }
1978 tty->print("\n");
1979 }
1980 #endif