1 /*
2 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "libadt/vectset.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "opto/block.hpp"
29 #include "opto/c2compiler.hpp"
30 #include "opto/callnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/machnode.hpp"
33 #include "opto/opcodes.hpp"
34 #include "opto/phaseX.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/runtime.hpp"
37 #include "runtime/deoptimization.hpp"
38 #ifdef TARGET_ARCH_MODEL_x86_32
39 # include "adfiles/ad_x86_32.hpp"
40 #endif
41 #ifdef TARGET_ARCH_MODEL_x86_64
42 # include "adfiles/ad_x86_64.hpp"
43 #endif
44 #ifdef TARGET_ARCH_MODEL_sparc
45 # include "adfiles/ad_sparc.hpp"
46 #endif
47 #ifdef TARGET_ARCH_MODEL_zero
48 # include "adfiles/ad_zero.hpp"
49 #endif
50 #ifdef TARGET_ARCH_MODEL_arm
51 # include "adfiles/ad_arm.hpp"
52 #endif
53 #ifdef TARGET_ARCH_MODEL_ppc
54 # include "adfiles/ad_ppc.hpp"
55 #endif
56
57 // Portions of code courtesy of Clifford Click
58
59 // Optimization - Graph Style
60
61 // To avoid float value underflow
62 #define MIN_BLOCK_FREQUENCY 1.e-35f
63
64 //----------------------------schedule_node_into_block-------------------------
65 // Insert node n into block b. Look for projections of n and make sure they
66 // are in b also.
67 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) {
68 // Set basic block of n, Add n to b,
69 _bbs.map(n->_idx, b);
70 b->add_inst(n);
71
72 // After Matching, nearly any old Node may have projections trailing it.
73 // These are usually machine-dependent flags. In any case, they might
74 // float to another block below this one. Move them up.
75 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
76 Node* use = n->fast_out(i);
77 if (use->is_Proj()) {
78 Block* buse = _bbs[use->_idx];
79 if (buse != b) { // In wrong block?
80 if (buse != NULL)
81 buse->find_remove(use); // Remove from wrong block
82 _bbs.map(use->_idx, b); // Re-insert in this block
83 b->add_inst(use);
84 }
85 }
86 }
87 }
88
89 //----------------------------replace_block_proj_ctrl-------------------------
90 // Nodes that have is_block_proj() nodes as their control need to use
91 // the appropriate Region for their actual block as their control since
92 // the projection will be in a predecessor block.
93 void PhaseCFG::replace_block_proj_ctrl( Node *n ) {
94 const Node *in0 = n->in(0);
95 assert(in0 != NULL, "Only control-dependent");
96 const Node *p = in0->is_block_proj();
97 if (p != NULL && p != n) { // Control from a block projection?
98 assert(!n->pinned() || n->is_MachConstantBase() || n->is_SafePointScalarObject(), "only pinned MachConstantBase or SafePointScalarObject node is expected here");
99 // Find trailing Region
100 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block
101 uint j = 0;
102 if (pb->_num_succs != 1) { // More then 1 successor?
103 // Search for successor
104 uint max = pb->_nodes.size();
105 assert( max > 1, "" );
106 uint start = max - pb->_num_succs;
107 // Find which output path belongs to projection
108 for (j = start; j < max; j++) {
109 if( pb->_nodes[j] == in0 )
110 break;
111 }
112 assert( j < max, "must find" );
113 // Change control to match head of successor basic block
114 j -= start;
115 }
116 n->set_req(0, pb->_succs[j]->head());
117 }
118 }
119
120
121 //------------------------------schedule_pinned_nodes--------------------------
122 // Set the basic block for Nodes pinned into blocks
123 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) {
124 // Allocate node stack of size C->unique()+8 to avoid frequent realloc
125 GrowableArray <Node *> spstack(C->unique()+8);
126 spstack.push(_root);
127 while ( spstack.is_nonempty() ) {
128 Node *n = spstack.pop();
129 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited
130 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down!
131 assert( n->in(0), "pinned Node must have Control" );
132 // Before setting block replace block_proj control edge
133 replace_block_proj_ctrl(n);
134 Node *input = n->in(0);
135 while( !input->is_block_start() )
136 input = input->in(0);
137 Block *b = _bbs[input->_idx]; // Basic block of controlling input
138 schedule_node_into_block(n, b);
139 }
140 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs
141 if( n->in(i) != NULL )
142 spstack.push(n->in(i));
143 }
144 }
145 }
146 }
147
148 #ifdef ASSERT
149 // Assert that new input b2 is dominated by all previous inputs.
150 // Check this by by seeing that it is dominated by b1, the deepest
151 // input observed until b2.
152 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) {
153 if (b1 == NULL) return;
154 assert(b1->_dom_depth < b2->_dom_depth, "sanity");
155 Block* tmp = b2;
156 while (tmp != b1 && tmp != NULL) {
157 tmp = tmp->_idom;
158 }
159 if (tmp != b1) {
160 // Detected an unschedulable graph. Print some nice stuff and die.
161 tty->print_cr("!!! Unschedulable graph !!!");
162 for (uint j=0; j<n->len(); j++) { // For all inputs
163 Node* inn = n->in(j); // Get input
164 if (inn == NULL) continue; // Ignore NULL, missing inputs
165 Block* inb = bbs[inn->_idx];
166 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order,
167 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth);
168 inn->dump();
169 }
170 tty->print("Failing node: ");
171 n->dump();
172 assert(false, "unscheduable graph");
173 }
174 }
175 #endif
176
177 static Block* find_deepest_input(Node* n, Block_Array &bbs) {
178 // Find the last input dominated by all other inputs.
179 Block* deepb = NULL; // Deepest block so far
180 int deepb_dom_depth = 0;
181 for (uint k = 0; k < n->len(); k++) { // For all inputs
182 Node* inn = n->in(k); // Get input
183 if (inn == NULL) continue; // Ignore NULL, missing inputs
184 Block* inb = bbs[inn->_idx];
185 assert(inb != NULL, "must already have scheduled this input");
186 if (deepb_dom_depth < (int) inb->_dom_depth) {
187 // The new inb must be dominated by the previous deepb.
188 // The various inputs must be linearly ordered in the dom
189 // tree, or else there will not be a unique deepest block.
190 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs));
191 deepb = inb; // Save deepest block
192 deepb_dom_depth = deepb->_dom_depth;
193 }
194 }
195 assert(deepb != NULL, "must be at least one input to n");
196 return deepb;
197 }
198
199
200 //------------------------------schedule_early---------------------------------
201 // Find the earliest Block any instruction can be placed in. Some instructions
202 // are pinned into Blocks. Unpinned instructions can appear in last block in
203 // which all their inputs occur.
204 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) {
205 // Allocate stack with enough space to avoid frequent realloc
206 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats
207 // roots.push(_root); _root will be processed among C->top() inputs
208 roots.push(C->top());
209 visited.set(C->top()->_idx);
210
211 while (roots.size() != 0) {
212 // Use local variables nstack_top_n & nstack_top_i to cache values
213 // on stack's top.
214 Node *nstack_top_n = roots.pop();
215 uint nstack_top_i = 0;
216 //while_nstack_nonempty:
217 while (true) {
218 // Get parent node and next input's index from stack's top.
219 Node *n = nstack_top_n;
220 uint i = nstack_top_i;
221
222 if (i == 0) {
223 // Fixup some control. Constants without control get attached
224 // to root and nodes that use is_block_proj() nodes should be attached
225 // to the region that starts their block.
226 const Node *in0 = n->in(0);
227 if (in0 != NULL) { // Control-dependent?
228 replace_block_proj_ctrl(n);
229 } else { // n->in(0) == NULL
230 if (n->req() == 1) { // This guy is a constant with NO inputs?
231 n->set_req(0, _root);
232 }
233 }
234 }
235
236 // First, visit all inputs and force them to get a block. If an
237 // input is already in a block we quit following inputs (to avoid
238 // cycles). Instead we put that Node on a worklist to be handled
239 // later (since IT'S inputs may not have a block yet).
240 bool done = true; // Assume all n's inputs will be processed
241 while (i < n->len()) { // For all inputs
242 Node *in = n->in(i); // Get input
243 ++i;
244 if (in == NULL) continue; // Ignore NULL, missing inputs
245 int is_visited = visited.test_set(in->_idx);
246 if (!_bbs.lookup(in->_idx)) { // Missing block selection?
247 if (is_visited) {
248 // assert( !visited.test(in->_idx), "did not schedule early" );
249 return false;
250 }
251 nstack.push(n, i); // Save parent node and next input's index.
252 nstack_top_n = in; // Process current input now.
253 nstack_top_i = 0;
254 done = false; // Not all n's inputs processed.
255 break; // continue while_nstack_nonempty;
256 } else if (!is_visited) { // Input not yet visited?
257 roots.push(in); // Visit this guy later, using worklist
258 }
259 }
260 if (done) {
261 // All of n's inputs have been processed, complete post-processing.
262
263 // Some instructions are pinned into a block. These include Region,
264 // Phi, Start, Return, and other control-dependent instructions and
265 // any projections which depend on them.
266 if (!n->pinned()) {
267 // Set earliest legal block.
268 _bbs.map(n->_idx, find_deepest_input(n, _bbs));
269 } else {
270 assert(_bbs[n->_idx] == _bbs[n->in(0)->_idx], "Pinned Node should be at the same block as its control edge");
271 }
272
273 if (nstack.is_empty()) {
274 // Finished all nodes on stack.
275 // Process next node on the worklist 'roots'.
276 break;
277 }
278 // Get saved parent node and next input's index.
279 nstack_top_n = nstack.node();
280 nstack_top_i = nstack.index();
281 nstack.pop();
282 } // if (done)
283 } // while (true)
284 } // while (roots.size() != 0)
285 return true;
286 }
287
288 //------------------------------dom_lca----------------------------------------
289 // Find least common ancestor in dominator tree
290 // LCA is a current notion of LCA, to be raised above 'this'.
291 // As a convenient boundary condition, return 'this' if LCA is NULL.
292 // Find the LCA of those two nodes.
293 Block* Block::dom_lca(Block* LCA) {
294 if (LCA == NULL || LCA == this) return this;
295
296 Block* anc = this;
297 while (anc->_dom_depth > LCA->_dom_depth)
298 anc = anc->_idom; // Walk up till anc is as high as LCA
299
300 while (LCA->_dom_depth > anc->_dom_depth)
301 LCA = LCA->_idom; // Walk up till LCA is as high as anc
302
303 while (LCA != anc) { // Walk both up till they are the same
304 LCA = LCA->_idom;
305 anc = anc->_idom;
306 }
307
308 return LCA;
309 }
310
311 //--------------------------raise_LCA_above_use--------------------------------
312 // We are placing a definition, and have been given a def->use edge.
313 // The definition must dominate the use, so move the LCA upward in the
314 // dominator tree to dominate the use. If the use is a phi, adjust
315 // the LCA only with the phi input paths which actually use this def.
316 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) {
317 Block* buse = bbs[use->_idx];
318 if (buse == NULL) return LCA; // Unused killing Projs have no use block
319 if (!use->is_Phi()) return buse->dom_lca(LCA);
320 uint pmax = use->req(); // Number of Phi inputs
321 // Why does not this loop just break after finding the matching input to
322 // the Phi? Well...it's like this. I do not have true def-use/use-def
323 // chains. Means I cannot distinguish, from the def-use direction, which
324 // of many use-defs lead from the same use to the same def. That is, this
325 // Phi might have several uses of the same def. Each use appears in a
326 // different predecessor block. But when I enter here, I cannot distinguish
327 // which use-def edge I should find the predecessor block for. So I find
328 // them all. Means I do a little extra work if a Phi uses the same value
329 // more than once.
330 for (uint j=1; j<pmax; j++) { // For all inputs
331 if (use->in(j) == def) { // Found matching input?
332 Block* pred = bbs[buse->pred(j)->_idx];
333 LCA = pred->dom_lca(LCA);
334 }
335 }
336 return LCA;
337 }
338
339 //----------------------------raise_LCA_above_marks----------------------------
340 // Return a new LCA that dominates LCA and any of its marked predecessors.
341 // Search all my parents up to 'early' (exclusive), looking for predecessors
342 // which are marked with the given index. Return the LCA (in the dom tree)
343 // of all marked blocks. If there are none marked, return the original
344 // LCA.
345 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark,
346 Block* early, Block_Array &bbs) {
347 Block_List worklist;
348 worklist.push(LCA);
349 while (worklist.size() > 0) {
350 Block* mid = worklist.pop();
351 if (mid == early) continue; // stop searching here
352
353 // Test and set the visited bit.
354 if (mid->raise_LCA_visited() == mark) continue; // already visited
355
356 // Don't process the current LCA, otherwise the search may terminate early
357 if (mid != LCA && mid->raise_LCA_mark() == mark) {
358 // Raise the LCA.
359 LCA = mid->dom_lca(LCA);
360 if (LCA == early) break; // stop searching everywhere
361 assert(early->dominates(LCA), "early is high enough");
362 // Resume searching at that point, skipping intermediate levels.
363 worklist.push(LCA);
364 if (LCA == mid)
365 continue; // Don't mark as visited to avoid early termination.
366 } else {
367 // Keep searching through this block's predecessors.
368 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) {
369 Block* mid_parent = bbs[ mid->pred(j)->_idx ];
370 worklist.push(mid_parent);
371 }
372 }
373 mid->set_raise_LCA_visited(mark);
374 }
375 return LCA;
376 }
377
378 //--------------------------memory_early_block--------------------------------
379 // This is a variation of find_deepest_input, the heart of schedule_early.
380 // Find the "early" block for a load, if we considered only memory and
381 // address inputs, that is, if other data inputs were ignored.
382 //
383 // Because a subset of edges are considered, the resulting block will
384 // be earlier (at a shallower dom_depth) than the true schedule_early
385 // point of the node. We compute this earlier block as a more permissive
386 // site for anti-dependency insertion, but only if subsume_loads is enabled.
387 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) {
388 Node* base;
389 Node* index;
390 Node* store = load->in(MemNode::Memory);
391 load->as_Mach()->memory_inputs(base, index);
392
393 assert(base != NodeSentinel && index != NodeSentinel,
394 "unexpected base/index inputs");
395
396 Node* mem_inputs[4];
397 int mem_inputs_length = 0;
398 if (base != NULL) mem_inputs[mem_inputs_length++] = base;
399 if (index != NULL) mem_inputs[mem_inputs_length++] = index;
400 if (store != NULL) mem_inputs[mem_inputs_length++] = store;
401
402 // In the comparision below, add one to account for the control input,
403 // which may be null, but always takes up a spot in the in array.
404 if (mem_inputs_length + 1 < (int) load->req()) {
405 // This "load" has more inputs than just the memory, base and index inputs.
406 // For purposes of checking anti-dependences, we need to start
407 // from the early block of only the address portion of the instruction,
408 // and ignore other blocks that may have factored into the wider
409 // schedule_early calculation.
410 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0);
411
412 Block* deepb = NULL; // Deepest block so far
413 int deepb_dom_depth = 0;
414 for (int i = 0; i < mem_inputs_length; i++) {
415 Block* inb = bbs[mem_inputs[i]->_idx];
416 if (deepb_dom_depth < (int) inb->_dom_depth) {
417 // The new inb must be dominated by the previous deepb.
418 // The various inputs must be linearly ordered in the dom
419 // tree, or else there will not be a unique deepest block.
420 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs));
421 deepb = inb; // Save deepest block
422 deepb_dom_depth = deepb->_dom_depth;
423 }
424 }
425 early = deepb;
426 }
427
428 return early;
429 }
430
431 //--------------------------insert_anti_dependences---------------------------
432 // A load may need to witness memory that nearby stores can overwrite.
433 // For each nearby store, either insert an "anti-dependence" edge
434 // from the load to the store, or else move LCA upward to force the
435 // load to (eventually) be scheduled in a block above the store.
436 //
437 // Do not add edges to stores on distinct control-flow paths;
438 // only add edges to stores which might interfere.
439 //
440 // Return the (updated) LCA. There will not be any possibly interfering
441 // store between the load's "early block" and the updated LCA.
442 // Any stores in the updated LCA will have new precedence edges
443 // back to the load. The caller is expected to schedule the load
444 // in the LCA, in which case the precedence edges will make LCM
445 // preserve anti-dependences. The caller may also hoist the load
446 // above the LCA, if it is not the early block.
447 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) {
448 assert(load->needs_anti_dependence_check(), "must be a load of some sort");
449 assert(LCA != NULL, "");
450 DEBUG_ONLY(Block* LCA_orig = LCA);
451
452 // Compute the alias index. Loads and stores with different alias indices
453 // do not need anti-dependence edges.
454 uint load_alias_idx = C->get_alias_index(load->adr_type());
455 #ifdef ASSERT
456 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 &&
457 (PrintOpto || VerifyAliases ||
458 PrintMiscellaneous && (WizardMode || Verbose))) {
459 // Load nodes should not consume all of memory.
460 // Reporting a bottom type indicates a bug in adlc.
461 // If some particular type of node validly consumes all of memory,
462 // sharpen the preceding "if" to exclude it, so we can catch bugs here.
463 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory.");
464 load->dump(2);
465 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, "");
466 }
467 #endif
468 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp),
469 "String compare is only known 'load' that does not conflict with any stores");
470 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrEquals),
471 "String equals is a 'load' that does not conflict with any stores");
472 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOf),
473 "String indexOf is a 'load' that does not conflict with any stores");
474 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_AryEq),
475 "Arrays equals is a 'load' that do not conflict with any stores");
476
477 if (!C->alias_type(load_alias_idx)->is_rewritable()) {
478 // It is impossible to spoil this load by putting stores before it,
479 // because we know that the stores will never update the value
480 // which 'load' must witness.
481 return LCA;
482 }
483
484 node_idx_t load_index = load->_idx;
485
486 // Note the earliest legal placement of 'load', as determined by
487 // by the unique point in the dom tree where all memory effects
488 // and other inputs are first available. (Computed by schedule_early.)
489 // For normal loads, 'early' is the shallowest place (dom graph wise)
490 // to look for anti-deps between this load and any store.
491 Block* early = _bbs[load_index];
492
493 // If we are subsuming loads, compute an "early" block that only considers
494 // memory or address inputs. This block may be different than the
495 // schedule_early block in that it could be at an even shallower depth in the
496 // dominator tree, and allow for a broader discovery of anti-dependences.
497 if (C->subsume_loads()) {
498 early = memory_early_block(load, early, _bbs);
499 }
500
501 ResourceArea *area = Thread::current()->resource_area();
502 Node_List worklist_mem(area); // prior memory state to store
503 Node_List worklist_store(area); // possible-def to explore
504 Node_List worklist_visited(area); // visited mergemem nodes
505 Node_List non_early_stores(area); // all relevant stores outside of early
506 bool must_raise_LCA = false;
507
508 #ifdef TRACK_PHI_INPUTS
509 // %%% This extra checking fails because MergeMem nodes are not GVNed.
510 // Provide "phi_inputs" to check if every input to a PhiNode is from the
511 // original memory state. This indicates a PhiNode for which should not
512 // prevent the load from sinking. For such a block, set_raise_LCA_mark
513 // may be overly conservative.
514 // Mechanism: count inputs seen for each Phi encountered in worklist_store.
515 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0));
516 #endif
517
518 // 'load' uses some memory state; look for users of the same state.
519 // Recurse through MergeMem nodes to the stores that use them.
520
521 // Each of these stores is a possible definition of memory
522 // that 'load' needs to use. We need to force 'load'
523 // to occur before each such store. When the store is in
524 // the same block as 'load', we insert an anti-dependence
525 // edge load->store.
526
527 // The relevant stores "nearby" the load consist of a tree rooted
528 // at initial_mem, with internal nodes of type MergeMem.
529 // Therefore, the branches visited by the worklist are of this form:
530 // initial_mem -> (MergeMem ->)* store
531 // The anti-dependence constraints apply only to the fringe of this tree.
532
533 Node* initial_mem = load->in(MemNode::Memory);
534 worklist_store.push(initial_mem);
535 worklist_visited.push(initial_mem);
536 worklist_mem.push(NULL);
537 while (worklist_store.size() > 0) {
538 // Examine a nearby store to see if it might interfere with our load.
539 Node* mem = worklist_mem.pop();
540 Node* store = worklist_store.pop();
541 uint op = store->Opcode();
542
543 // MergeMems do not directly have anti-deps.
544 // Treat them as internal nodes in a forward tree of memory states,
545 // the leaves of which are each a 'possible-def'.
546 if (store == initial_mem // root (exclusive) of tree we are searching
547 || op == Op_MergeMem // internal node of tree we are searching
548 ) {
549 mem = store; // It's not a possibly interfering store.
550 if (store == initial_mem)
551 initial_mem = NULL; // only process initial memory once
552
553 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
554 store = mem->fast_out(i);
555 if (store->is_MergeMem()) {
556 // Be sure we don't get into combinatorial problems.
557 // (Allow phis to be repeated; they can merge two relevant states.)
558 uint j = worklist_visited.size();
559 for (; j > 0; j--) {
560 if (worklist_visited.at(j-1) == store) break;
561 }
562 if (j > 0) continue; // already on work list; do not repeat
563 worklist_visited.push(store);
564 }
565 worklist_mem.push(mem);
566 worklist_store.push(store);
567 }
568 continue;
569 }
570
571 if (op == Op_MachProj || op == Op_Catch) continue;
572 if (store->needs_anti_dependence_check()) continue; // not really a store
573
574 // Compute the alias index. Loads and stores with different alias
575 // indices do not need anti-dependence edges. Wide MemBar's are
576 // anti-dependent on everything (except immutable memories).
577 const TypePtr* adr_type = store->adr_type();
578 if (!C->can_alias(adr_type, load_alias_idx)) continue;
579
580 // Most slow-path runtime calls do NOT modify Java memory, but
581 // they can block and so write Raw memory.
582 if (store->is_Mach()) {
583 MachNode* mstore = store->as_Mach();
584 if (load_alias_idx != Compile::AliasIdxRaw) {
585 // Check for call into the runtime using the Java calling
586 // convention (and from there into a wrapper); it has no
587 // _method. Can't do this optimization for Native calls because
588 // they CAN write to Java memory.
589 if (mstore->ideal_Opcode() == Op_CallStaticJava) {
590 assert(mstore->is_MachSafePoint(), "");
591 MachSafePointNode* ms = (MachSafePointNode*) mstore;
592 assert(ms->is_MachCallJava(), "");
593 MachCallJavaNode* mcj = (MachCallJavaNode*) ms;
594 if (mcj->_method == NULL) {
595 // These runtime calls do not write to Java visible memory
596 // (other than Raw) and so do not require anti-dependence edges.
597 continue;
598 }
599 }
600 // Same for SafePoints: they read/write Raw but only read otherwise.
601 // This is basically a workaround for SafePoints only defining control
602 // instead of control + memory.
603 if (mstore->ideal_Opcode() == Op_SafePoint)
604 continue;
605 } else {
606 // Some raw memory, such as the load of "top" at an allocation,
607 // can be control dependent on the previous safepoint. See
608 // comments in GraphKit::allocate_heap() about control input.
609 // Inserting an anti-dep between such a safepoint and a use
610 // creates a cycle, and will cause a subsequent failure in
611 // local scheduling. (BugId 4919904)
612 // (%%% How can a control input be a safepoint and not a projection??)
613 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore)
614 continue;
615 }
616 }
617
618 // Identify a block that the current load must be above,
619 // or else observe that 'store' is all the way up in the
620 // earliest legal block for 'load'. In the latter case,
621 // immediately insert an anti-dependence edge.
622 Block* store_block = _bbs[store->_idx];
623 assert(store_block != NULL, "unused killing projections skipped above");
624
625 if (store->is_Phi()) {
626 // 'load' uses memory which is one (or more) of the Phi's inputs.
627 // It must be scheduled not before the Phi, but rather before
628 // each of the relevant Phi inputs.
629 //
630 // Instead of finding the LCA of all inputs to a Phi that match 'mem',
631 // we mark each corresponding predecessor block and do a combined
632 // hoisting operation later (raise_LCA_above_marks).
633 //
634 // Do not assert(store_block != early, "Phi merging memory after access")
635 // PhiNode may be at start of block 'early' with backedge to 'early'
636 DEBUG_ONLY(bool found_match = false);
637 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) {
638 if (store->in(j) == mem) { // Found matching input?
639 DEBUG_ONLY(found_match = true);
640 Block* pred_block = _bbs[store_block->pred(j)->_idx];
641 if (pred_block != early) {
642 // If any predecessor of the Phi matches the load's "early block",
643 // we do not need a precedence edge between the Phi and 'load'
644 // since the load will be forced into a block preceding the Phi.
645 pred_block->set_raise_LCA_mark(load_index);
646 assert(!LCA_orig->dominates(pred_block) ||
647 early->dominates(pred_block), "early is high enough");
648 must_raise_LCA = true;
649 } else {
650 // anti-dependent upon PHI pinned below 'early', no edge needed
651 LCA = early; // but can not schedule below 'early'
652 }
653 }
654 }
655 assert(found_match, "no worklist bug");
656 #ifdef TRACK_PHI_INPUTS
657 #ifdef ASSERT
658 // This assert asks about correct handling of PhiNodes, which may not
659 // have all input edges directly from 'mem'. See BugId 4621264
660 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1;
661 // Increment by exactly one even if there are multiple copies of 'mem'
662 // coming into the phi, because we will run this block several times
663 // if there are several copies of 'mem'. (That's how DU iterators work.)
664 phi_inputs.at_put(store->_idx, num_mem_inputs);
665 assert(PhiNode::Input + num_mem_inputs < store->req(),
666 "Expect at least one phi input will not be from original memory state");
667 #endif //ASSERT
668 #endif //TRACK_PHI_INPUTS
669 } else if (store_block != early) {
670 // 'store' is between the current LCA and earliest possible block.
671 // Label its block, and decide later on how to raise the LCA
672 // to include the effect on LCA of this store.
673 // If this store's block gets chosen as the raised LCA, we
674 // will find him on the non_early_stores list and stick him
675 // with a precedence edge.
676 // (But, don't bother if LCA is already raised all the way.)
677 if (LCA != early) {
678 store_block->set_raise_LCA_mark(load_index);
679 must_raise_LCA = true;
680 non_early_stores.push(store);
681 }
682 } else {
683 // Found a possibly-interfering store in the load's 'early' block.
684 // This means 'load' cannot sink at all in the dominator tree.
685 // Add an anti-dep edge, and squeeze 'load' into the highest block.
686 assert(store != load->in(0), "dependence cycle found");
687 if (verify) {
688 assert(store->find_edge(load) != -1, "missing precedence edge");
689 } else {
690 store->add_prec(load);
691 }
692 LCA = early;
693 // This turns off the process of gathering non_early_stores.
694 }
695 }
696 // (Worklist is now empty; all nearby stores have been visited.)
697
698 // Finished if 'load' must be scheduled in its 'early' block.
699 // If we found any stores there, they have already been given
700 // precedence edges.
701 if (LCA == early) return LCA;
702
703 // We get here only if there are no possibly-interfering stores
704 // in the load's 'early' block. Move LCA up above all predecessors
705 // which contain stores we have noted.
706 //
707 // The raised LCA block can be a home to such interfering stores,
708 // but its predecessors must not contain any such stores.
709 //
710 // The raised LCA will be a lower bound for placing the load,
711 // preventing the load from sinking past any block containing
712 // a store that may invalidate the memory state required by 'load'.
713 if (must_raise_LCA)
714 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs);
715 if (LCA == early) return LCA;
716
717 // Insert anti-dependence edges from 'load' to each store
718 // in the non-early LCA block.
719 // Mine the non_early_stores list for such stores.
720 if (LCA->raise_LCA_mark() == load_index) {
721 while (non_early_stores.size() > 0) {
722 Node* store = non_early_stores.pop();
723 Block* store_block = _bbs[store->_idx];
724 if (store_block == LCA) {
725 // add anti_dependence from store to load in its own block
726 assert(store != load->in(0), "dependence cycle found");
727 if (verify) {
728 assert(store->find_edge(load) != -1, "missing precedence edge");
729 } else {
730 store->add_prec(load);
731 }
732 } else {
733 assert(store_block->raise_LCA_mark() == load_index, "block was marked");
734 // Any other stores we found must be either inside the new LCA
735 // or else outside the original LCA. In the latter case, they
736 // did not interfere with any use of 'load'.
737 assert(LCA->dominates(store_block)
738 || !LCA_orig->dominates(store_block), "no stray stores");
739 }
740 }
741 }
742
743 // Return the highest block containing stores; any stores
744 // within that block have been given anti-dependence edges.
745 return LCA;
746 }
747
748 // This class is used to iterate backwards over the nodes in the graph.
749
750 class Node_Backward_Iterator {
751
752 private:
753 Node_Backward_Iterator();
754
755 public:
756 // Constructor for the iterator
757 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs);
758
759 // Postincrement operator to iterate over the nodes
760 Node *next();
761
762 private:
763 VectorSet &_visited;
764 Node_List &_stack;
765 Block_Array &_bbs;
766 };
767
768 // Constructor for the Node_Backward_Iterator
769 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs )
770 : _visited(visited), _stack(stack), _bbs(bbs) {
771 // The stack should contain exactly the root
772 stack.clear();
773 stack.push(root);
774
775 // Clear the visited bits
776 visited.Clear();
777 }
778
779 // Iterator for the Node_Backward_Iterator
780 Node *Node_Backward_Iterator::next() {
781
782 // If the _stack is empty, then just return NULL: finished.
783 if ( !_stack.size() )
784 return NULL;
785
786 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been
787 // made stateless, so I do not need to record the index 'i' on my _stack.
788 // Instead I visit all users each time, scanning for unvisited users.
789 // I visit unvisited not-anti-dependence users first, then anti-dependent
790 // children next.
791 Node *self = _stack.pop();
792
793 // I cycle here when I am entering a deeper level of recursion.
794 // The key variable 'self' was set prior to jumping here.
795 while( 1 ) {
796
797 _visited.set(self->_idx);
798
799 // Now schedule all uses as late as possible.
800 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx;
801 uint src_rpo = _bbs[src]->_rpo;
802
803 // Schedule all nodes in a post-order visit
804 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any
805
806 // Scan for unvisited nodes
807 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
808 // For all uses, schedule late
809 Node* n = self->fast_out(i); // Use
810
811 // Skip already visited children
812 if ( _visited.test(n->_idx) )
813 continue;
814
815 // do not traverse backward control edges
816 Node *use = n->is_Proj() ? n->in(0) : n;
817 uint use_rpo = _bbs[use->_idx]->_rpo;
818
819 if ( use_rpo < src_rpo )
820 continue;
821
822 // Phi nodes always precede uses in a basic block
823 if ( use_rpo == src_rpo && use->is_Phi() )
824 continue;
825
826 unvisited = n; // Found unvisited
827
828 // Check for possible-anti-dependent
829 if( !n->needs_anti_dependence_check() )
830 break; // Not visited, not anti-dep; schedule it NOW
831 }
832
833 // Did I find an unvisited not-anti-dependent Node?
834 if ( !unvisited )
835 break; // All done with children; post-visit 'self'
836
837 // Visit the unvisited Node. Contains the obvious push to
838 // indicate I'm entering a deeper level of recursion. I push the
839 // old state onto the _stack and set a new state and loop (recurse).
840 _stack.push(self);
841 self = unvisited;
842 } // End recursion loop
843
844 return self;
845 }
846
847 //------------------------------ComputeLatenciesBackwards----------------------
848 // Compute the latency of all the instructions.
849 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) {
850 #ifndef PRODUCT
851 if (trace_opto_pipelining())
852 tty->print("\n#---- ComputeLatenciesBackwards ----\n");
853 #endif
854
855 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
856 Node *n;
857
858 // Walk over all the nodes from last to first
859 while (n = iter.next()) {
860 // Set the latency for the definitions of this instruction
861 partial_latency_of_defs(n);
862 }
863 } // end ComputeLatenciesBackwards
864
865 //------------------------------partial_latency_of_defs------------------------
866 // Compute the latency impact of this node on all defs. This computes
867 // a number that increases as we approach the beginning of the routine.
868 void PhaseCFG::partial_latency_of_defs(Node *n) {
869 // Set the latency for this instruction
870 #ifndef PRODUCT
871 if (trace_opto_pipelining()) {
872 tty->print("# latency_to_inputs: node_latency[%d] = %d for node",
873 n->_idx, _node_latency->at_grow(n->_idx));
874 dump();
875 }
876 #endif
877
878 if (n->is_Proj())
879 n = n->in(0);
880
881 if (n->is_Root())
882 return;
883
884 uint nlen = n->len();
885 uint use_latency = _node_latency->at_grow(n->_idx);
886 uint use_pre_order = _bbs[n->_idx]->_pre_order;
887
888 for ( uint j=0; j<nlen; j++ ) {
889 Node *def = n->in(j);
890
891 if (!def || def == n)
892 continue;
893
894 // Walk backwards thru projections
895 if (def->is_Proj())
896 def = def->in(0);
897
898 #ifndef PRODUCT
899 if (trace_opto_pipelining()) {
900 tty->print("# in(%2d): ", j);
901 def->dump();
902 }
903 #endif
904
905 // If the defining block is not known, assume it is ok
906 Block *def_block = _bbs[def->_idx];
907 uint def_pre_order = def_block ? def_block->_pre_order : 0;
908
909 if ( (use_pre_order < def_pre_order) ||
910 (use_pre_order == def_pre_order && n->is_Phi()) )
911 continue;
912
913 uint delta_latency = n->latency(j);
914 uint current_latency = delta_latency + use_latency;
915
916 if (_node_latency->at_grow(def->_idx) < current_latency) {
917 _node_latency->at_put_grow(def->_idx, current_latency);
918 }
919
920 #ifndef PRODUCT
921 if (trace_opto_pipelining()) {
922 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d",
923 use_latency, j, delta_latency, current_latency, def->_idx,
924 _node_latency->at_grow(def->_idx));
925 }
926 #endif
927 }
928 }
929
930 //------------------------------latency_from_use-------------------------------
931 // Compute the latency of a specific use
932 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) {
933 // If self-reference, return no latency
934 if (use == n || use->is_Root())
935 return 0;
936
937 uint def_pre_order = _bbs[def->_idx]->_pre_order;
938 uint latency = 0;
939
940 // If the use is not a projection, then it is simple...
941 if (!use->is_Proj()) {
942 #ifndef PRODUCT
943 if (trace_opto_pipelining()) {
944 tty->print("# out(): ");
945 use->dump();
946 }
947 #endif
948
949 uint use_pre_order = _bbs[use->_idx]->_pre_order;
950
951 if (use_pre_order < def_pre_order)
952 return 0;
953
954 if (use_pre_order == def_pre_order && use->is_Phi())
955 return 0;
956
957 uint nlen = use->len();
958 uint nl = _node_latency->at_grow(use->_idx);
959
960 for ( uint j=0; j<nlen; j++ ) {
961 if (use->in(j) == n) {
962 // Change this if we want local latencies
963 uint ul = use->latency(j);
964 uint l = ul + nl;
965 if (latency < l) latency = l;
966 #ifndef PRODUCT
967 if (trace_opto_pipelining()) {
968 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d",
969 nl, j, ul, l, latency);
970 }
971 #endif
972 }
973 }
974 } else {
975 // This is a projection, just grab the latency of the use(s)
976 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) {
977 uint l = latency_from_use(use, def, use->fast_out(j));
978 if (latency < l) latency = l;
979 }
980 }
981
982 return latency;
983 }
984
985 //------------------------------latency_from_uses------------------------------
986 // Compute the latency of this instruction relative to all of it's uses.
987 // This computes a number that increases as we approach the beginning of the
988 // routine.
989 void PhaseCFG::latency_from_uses(Node *n) {
990 // Set the latency for this instruction
991 #ifndef PRODUCT
992 if (trace_opto_pipelining()) {
993 tty->print("# latency_from_outputs: node_latency[%d] = %d for node",
994 n->_idx, _node_latency->at_grow(n->_idx));
995 dump();
996 }
997 #endif
998 uint latency=0;
999 const Node *def = n->is_Proj() ? n->in(0): n;
1000
1001 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1002 uint l = latency_from_use(n, def, n->fast_out(i));
1003
1004 if (latency < l) latency = l;
1005 }
1006
1007 _node_latency->at_put_grow(n->_idx, latency);
1008 }
1009
1010 //------------------------------hoist_to_cheaper_block-------------------------
1011 // Pick a block for node self, between early and LCA, that is a cheaper
1012 // alternative to LCA.
1013 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) {
1014 const double delta = 1+PROB_UNLIKELY_MAG(4);
1015 Block* least = LCA;
1016 double least_freq = least->_freq;
1017 uint target = _node_latency->at_grow(self->_idx);
1018 uint start_latency = _node_latency->at_grow(LCA->_nodes[0]->_idx);
1019 uint end_latency = _node_latency->at_grow(LCA->_nodes[LCA->end_idx()]->_idx);
1020 bool in_latency = (target <= start_latency);
1021 const Block* root_block = _bbs[_root->_idx];
1022
1023 // Turn off latency scheduling if scheduling is just plain off
1024 if (!C->do_scheduling())
1025 in_latency = true;
1026
1027 // Do not hoist (to cover latency) instructions which target a
1028 // single register. Hoisting stretches the live range of the
1029 // single register and may force spilling.
1030 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
1031 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty())
1032 in_latency = true;
1033
1034 #ifndef PRODUCT
1035 if (trace_opto_pipelining()) {
1036 tty->print("# Find cheaper block for latency %d: ",
1037 _node_latency->at_grow(self->_idx));
1038 self->dump();
1039 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1040 LCA->_pre_order,
1041 LCA->_nodes[0]->_idx,
1042 start_latency,
1043 LCA->_nodes[LCA->end_idx()]->_idx,
1044 end_latency,
1045 least_freq);
1046 }
1047 #endif
1048
1049 // Walk up the dominator tree from LCA (Lowest common ancestor) to
1050 // the earliest legal location. Capture the least execution frequency.
1051 while (LCA != early) {
1052 LCA = LCA->_idom; // Follow up the dominator tree
1053
1054 if (LCA == NULL) {
1055 // Bailout without retry
1056 C->record_method_not_compilable("late schedule failed: LCA == NULL");
1057 return least;
1058 }
1059
1060 // Don't hoist machine instructions to the root basic block
1061 if (mach && LCA == root_block)
1062 break;
1063
1064 uint start_lat = _node_latency->at_grow(LCA->_nodes[0]->_idx);
1065 uint end_idx = LCA->end_idx();
1066 uint end_lat = _node_latency->at_grow(LCA->_nodes[end_idx]->_idx);
1067 double LCA_freq = LCA->_freq;
1068 #ifndef PRODUCT
1069 if (trace_opto_pipelining()) {
1070 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g",
1071 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq);
1072 }
1073 #endif
1074 if (LCA_freq < least_freq || // Better Frequency
1075 ( !in_latency && // No block containing latency
1076 LCA_freq < least_freq * delta && // No worse frequency
1077 target >= end_lat && // within latency range
1078 !self->is_iteratively_computed() ) // But don't hoist IV increments
1079 // because they may end up above other uses of their phi forcing
1080 // their result register to be different from their input.
1081 ) {
1082 least = LCA; // Found cheaper block
1083 least_freq = LCA_freq;
1084 start_latency = start_lat;
1085 end_latency = end_lat;
1086 if (target <= start_lat)
1087 in_latency = true;
1088 }
1089 }
1090
1091 #ifndef PRODUCT
1092 if (trace_opto_pipelining()) {
1093 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g",
1094 least->_pre_order, start_latency, least_freq);
1095 }
1096 #endif
1097
1098 // See if the latency needs to be updated
1099 if (target < end_latency) {
1100 #ifndef PRODUCT
1101 if (trace_opto_pipelining()) {
1102 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency);
1103 }
1104 #endif
1105 _node_latency->at_put_grow(self->_idx, end_latency);
1106 partial_latency_of_defs(self);
1107 }
1108
1109 return least;
1110 }
1111
1112
1113 //------------------------------schedule_late-----------------------------------
1114 // Now schedule all codes as LATE as possible. This is the LCA in the
1115 // dominator tree of all USES of a value. Pick the block with the least
1116 // loop nesting depth that is lowest in the dominator tree.
1117 extern const char must_clone[];
1118 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) {
1119 #ifndef PRODUCT
1120 if (trace_opto_pipelining())
1121 tty->print("\n#---- schedule_late ----\n");
1122 #endif
1123
1124 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs);
1125 Node *self;
1126
1127 // Walk over all the nodes from last to first
1128 while (self = iter.next()) {
1129 Block* early = _bbs[self->_idx]; // Earliest legal placement
1130
1131 if (self->is_top()) {
1132 // Top node goes in bb #2 with other constants.
1133 // It must be special-cased, because it has no out edges.
1134 early->add_inst(self);
1135 continue;
1136 }
1137
1138 // No uses, just terminate
1139 if (self->outcnt() == 0) {
1140 assert(self->is_MachProj(), "sanity");
1141 continue; // Must be a dead machine projection
1142 }
1143
1144 // If node is pinned in the block, then no scheduling can be done.
1145 if( self->pinned() ) // Pinned in block?
1146 continue;
1147
1148 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL;
1149 if (mach) {
1150 switch (mach->ideal_Opcode()) {
1151 case Op_CreateEx:
1152 // Don't move exception creation
1153 early->add_inst(self);
1154 continue;
1155 break;
1156 case Op_CheckCastPP:
1157 // Don't move CheckCastPP nodes away from their input, if the input
1158 // is a rawptr (5071820).
1159 Node *def = self->in(1);
1160 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) {
1161 early->add_inst(self);
1162 #ifdef ASSERT
1163 _raw_oops.push(def);
1164 #endif
1165 continue;
1166 }
1167 break;
1168 }
1169 }
1170
1171 // Gather LCA of all uses
1172 Block *LCA = NULL;
1173 {
1174 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) {
1175 // For all uses, find LCA
1176 Node* use = self->fast_out(i);
1177 LCA = raise_LCA_above_use(LCA, use, self, _bbs);
1178 }
1179 } // (Hide defs of imax, i from rest of block.)
1180
1181 // Place temps in the block of their use. This isn't a
1182 // requirement for correctness but it reduces useless
1183 // interference between temps and other nodes.
1184 if (mach != NULL && mach->is_MachTemp()) {
1185 _bbs.map(self->_idx, LCA);
1186 LCA->add_inst(self);
1187 continue;
1188 }
1189
1190 // Check if 'self' could be anti-dependent on memory
1191 if (self->needs_anti_dependence_check()) {
1192 // Hoist LCA above possible-defs and insert anti-dependences to
1193 // defs in new LCA block.
1194 LCA = insert_anti_dependences(LCA, self);
1195 }
1196
1197 if (early->_dom_depth > LCA->_dom_depth) {
1198 // Somehow the LCA has moved above the earliest legal point.
1199 // (One way this can happen is via memory_early_block.)
1200 if (C->subsume_loads() == true && !C->failing()) {
1201 // Retry with subsume_loads == false
1202 // If this is the first failure, the sentinel string will "stick"
1203 // to the Compile object, and the C2Compiler will see it and retry.
1204 C->record_failure(C2Compiler::retry_no_subsuming_loads());
1205 } else {
1206 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth)
1207 C->record_method_not_compilable("late schedule failed: incorrect graph");
1208 }
1209 return;
1210 }
1211
1212 // If there is no opportunity to hoist, then we're done.
1213 bool try_to_hoist = (LCA != early);
1214
1215 // Must clone guys stay next to use; no hoisting allowed.
1216 // Also cannot hoist guys that alter memory or are otherwise not
1217 // allocatable (hoisting can make a value live longer, leading to
1218 // anti and output dependency problems which are normally resolved
1219 // by the register allocator giving everyone a different register).
1220 if (mach != NULL && must_clone[mach->ideal_Opcode()])
1221 try_to_hoist = false;
1222
1223 Block* late = NULL;
1224 if (try_to_hoist) {
1225 // Now find the block with the least execution frequency.
1226 // Start at the latest schedule and work up to the earliest schedule
1227 // in the dominator tree. Thus the Node will dominate all its uses.
1228 late = hoist_to_cheaper_block(LCA, early, self);
1229 } else {
1230 // Just use the LCA of the uses.
1231 late = LCA;
1232 }
1233
1234 // Put the node into target block
1235 schedule_node_into_block(self, late);
1236
1237 #ifdef ASSERT
1238 if (self->needs_anti_dependence_check()) {
1239 // since precedence edges are only inserted when we're sure they
1240 // are needed make sure that after placement in a block we don't
1241 // need any new precedence edges.
1242 verify_anti_dependences(late, self);
1243 }
1244 #endif
1245 } // Loop until all nodes have been visited
1246
1247 } // end ScheduleLate
1248
1249 //------------------------------GlobalCodeMotion-------------------------------
1250 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) {
1251 ResourceMark rm;
1252
1253 #ifndef PRODUCT
1254 if (trace_opto_pipelining()) {
1255 tty->print("\n---- Start GlobalCodeMotion ----\n");
1256 }
1257 #endif
1258
1259 // Initialize the bbs.map for things on the proj_list
1260 uint i;
1261 for( i=0; i < proj_list.size(); i++ )
1262 _bbs.map(proj_list[i]->_idx, NULL);
1263
1264 // Set the basic block for Nodes pinned into blocks
1265 Arena *a = Thread::current()->resource_area();
1266 VectorSet visited(a);
1267 schedule_pinned_nodes( visited );
1268
1269 // Find the earliest Block any instruction can be placed in. Some
1270 // instructions are pinned into Blocks. Unpinned instructions can
1271 // appear in last block in which all their inputs occur.
1272 visited.Clear();
1273 Node_List stack(a);
1274 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list
1275 if (!schedule_early(visited, stack)) {
1276 // Bailout without retry
1277 C->record_method_not_compilable("early schedule failed");
1278 return;
1279 }
1280
1281 // Build Def-Use edges.
1282 proj_list.push(_root); // Add real root as another root
1283 proj_list.pop();
1284
1285 // Compute the latency information (via backwards walk) for all the
1286 // instructions in the graph
1287 _node_latency = new GrowableArray<uint>(); // resource_area allocation
1288
1289 if( C->do_scheduling() )
1290 ComputeLatenciesBackwards(visited, stack);
1291
1292 // Now schedule all codes as LATE as possible. This is the LCA in the
1293 // dominator tree of all USES of a value. Pick the block with the least
1294 // loop nesting depth that is lowest in the dominator tree.
1295 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() )
1296 schedule_late(visited, stack);
1297 if( C->failing() ) {
1298 // schedule_late fails only when graph is incorrect.
1299 assert(!VerifyGraphEdges, "verification should have failed");
1300 return;
1301 }
1302
1303 unique = C->unique();
1304
1305 #ifndef PRODUCT
1306 if (trace_opto_pipelining()) {
1307 tty->print("\n---- Detect implicit null checks ----\n");
1308 }
1309 #endif
1310
1311 // Detect implicit-null-check opportunities. Basically, find NULL checks
1312 // with suitable memory ops nearby. Use the memory op to do the NULL check.
1313 // I can generate a memory op if there is not one nearby.
1314 if (C->is_method_compilation()) {
1315 // Don't do it for natives, adapters, or runtime stubs
1316 int allowed_reasons = 0;
1317 // ...and don't do it when there have been too many traps, globally.
1318 for (int reason = (int)Deoptimization::Reason_none+1;
1319 reason < Compile::trapHistLength; reason++) {
1320 assert(reason < BitsPerInt, "recode bit map");
1321 if (!C->too_many_traps((Deoptimization::DeoptReason) reason))
1322 allowed_reasons |= nth_bit(reason);
1323 }
1324 // By reversing the loop direction we get a very minor gain on mpegaudio.
1325 // Feel free to revert to a forward loop for clarity.
1326 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) {
1327 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) {
1328 Node *proj = matcher._null_check_tests[i ];
1329 Node *val = matcher._null_check_tests[i+1];
1330 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons);
1331 // The implicit_null_check will only perform the transformation
1332 // if the null branch is truly uncommon, *and* it leads to an
1333 // uncommon trap. Combined with the too_many_traps guards
1334 // above, this prevents SEGV storms reported in 6366351,
1335 // by recompiling offending methods without this optimization.
1336 }
1337 }
1338
1339 #ifndef PRODUCT
1340 if (trace_opto_pipelining()) {
1341 tty->print("\n---- Start Local Scheduling ----\n");
1342 }
1343 #endif
1344
1345 // Schedule locally. Right now a simple topological sort.
1346 // Later, do a real latency aware scheduler.
1347 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique());
1348 memset( ready_cnt, -1, C->unique() * sizeof(int) );
1349 visited.Clear();
1350 for (i = 0; i < _num_blocks; i++) {
1351 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) {
1352 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) {
1353 C->record_method_not_compilable("local schedule failed");
1354 }
1355 return;
1356 }
1357 }
1358
1359 // If we inserted any instructions between a Call and his CatchNode,
1360 // clone the instructions on all paths below the Catch.
1361 for( i=0; i < _num_blocks; i++ )
1362 _blocks[i]->call_catch_cleanup(_bbs);
1363
1364 #ifndef PRODUCT
1365 if (trace_opto_pipelining()) {
1366 tty->print("\n---- After GlobalCodeMotion ----\n");
1367 for (uint i = 0; i < _num_blocks; i++) {
1368 _blocks[i]->dump();
1369 }
1370 }
1371 #endif
1372 // Dead.
1373 _node_latency = (GrowableArray<uint> *)0xdeadbeef;
1374 }
1375
1376
1377 //------------------------------Estimate_Block_Frequency-----------------------
1378 // Estimate block frequencies based on IfNode probabilities.
1379 void PhaseCFG::Estimate_Block_Frequency() {
1380
1381 // Force conditional branches leading to uncommon traps to be unlikely,
1382 // not because we get to the uncommon_trap with less relative frequency,
1383 // but because an uncommon_trap typically causes a deopt, so we only get
1384 // there once.
1385 if (C->do_freq_based_layout()) {
1386 Block_List worklist;
1387 Block* root_blk = _blocks[0];
1388 for (uint i = 1; i < root_blk->num_preds(); i++) {
1389 Block *pb = _bbs[root_blk->pred(i)->_idx];
1390 if (pb->has_uncommon_code()) {
1391 worklist.push(pb);
1392 }
1393 }
1394 while (worklist.size() > 0) {
1395 Block* uct = worklist.pop();
1396 if (uct == _broot) continue;
1397 for (uint i = 1; i < uct->num_preds(); i++) {
1398 Block *pb = _bbs[uct->pred(i)->_idx];
1399 if (pb->_num_succs == 1) {
1400 worklist.push(pb);
1401 } else if (pb->num_fall_throughs() == 2) {
1402 pb->update_uncommon_branch(uct);
1403 }
1404 }
1405 }
1406 }
1407
1408 // Create the loop tree and calculate loop depth.
1409 _root_loop = create_loop_tree();
1410 _root_loop->compute_loop_depth(0);
1411
1412 // Compute block frequency of each block, relative to a single loop entry.
1413 _root_loop->compute_freq();
1414
1415 // Adjust all frequencies to be relative to a single method entry
1416 _root_loop->_freq = 1.0;
1417 _root_loop->scale_freq();
1418
1419 // Save outmost loop frequency for LRG frequency threshold
1420 _outer_loop_freq = _root_loop->outer_loop_freq();
1421
1422 // force paths ending at uncommon traps to be infrequent
1423 if (!C->do_freq_based_layout()) {
1424 Block_List worklist;
1425 Block* root_blk = _blocks[0];
1426 for (uint i = 1; i < root_blk->num_preds(); i++) {
1427 Block *pb = _bbs[root_blk->pred(i)->_idx];
1428 if (pb->has_uncommon_code()) {
1429 worklist.push(pb);
1430 }
1431 }
1432 while (worklist.size() > 0) {
1433 Block* uct = worklist.pop();
1434 uct->_freq = PROB_MIN;
1435 for (uint i = 1; i < uct->num_preds(); i++) {
1436 Block *pb = _bbs[uct->pred(i)->_idx];
1437 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) {
1438 worklist.push(pb);
1439 }
1440 }
1441 }
1442 }
1443
1444 #ifdef ASSERT
1445 for (uint i = 0; i < _num_blocks; i++ ) {
1446 Block *b = _blocks[i];
1447 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency");
1448 }
1449 #endif
1450
1451 #ifndef PRODUCT
1452 if (PrintCFGBlockFreq) {
1453 tty->print_cr("CFG Block Frequencies");
1454 _root_loop->dump_tree();
1455 if (Verbose) {
1456 tty->print_cr("PhaseCFG dump");
1457 dump();
1458 tty->print_cr("Node dump");
1459 _root->dump(99999);
1460 }
1461 }
1462 #endif
1463 }
1464
1465 //----------------------------create_loop_tree--------------------------------
1466 // Create a loop tree from the CFG
1467 CFGLoop* PhaseCFG::create_loop_tree() {
1468
1469 #ifdef ASSERT
1470 assert( _blocks[0] == _broot, "" );
1471 for (uint i = 0; i < _num_blocks; i++ ) {
1472 Block *b = _blocks[i];
1473 // Check that _loop field are clear...we could clear them if not.
1474 assert(b->_loop == NULL, "clear _loop expected");
1475 // Sanity check that the RPO numbering is reflected in the _blocks array.
1476 // It doesn't have to be for the loop tree to be built, but if it is not,
1477 // then the blocks have been reordered since dom graph building...which
1478 // may question the RPO numbering
1479 assert(b->_rpo == i, "unexpected reverse post order number");
1480 }
1481 #endif
1482
1483 int idct = 0;
1484 CFGLoop* root_loop = new CFGLoop(idct++);
1485
1486 Block_List worklist;
1487
1488 // Assign blocks to loops
1489 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block
1490 Block *b = _blocks[i];
1491
1492 if (b->head()->is_Loop()) {
1493 Block* loop_head = b;
1494 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1495 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl);
1496 Block* tail = _bbs[tail_n->_idx];
1497
1498 // Defensively filter out Loop nodes for non-single-entry loops.
1499 // For all reasonable loops, the head occurs before the tail in RPO.
1500 if (i <= tail->_rpo) {
1501
1502 // The tail and (recursive) predecessors of the tail
1503 // are made members of a new loop.
1504
1505 assert(worklist.size() == 0, "nonempty worklist");
1506 CFGLoop* nloop = new CFGLoop(idct++);
1507 assert(loop_head->_loop == NULL, "just checking");
1508 loop_head->_loop = nloop;
1509 // Add to nloop so push_pred() will skip over inner loops
1510 nloop->add_member(loop_head);
1511 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs);
1512
1513 while (worklist.size() > 0) {
1514 Block* member = worklist.pop();
1515 if (member != loop_head) {
1516 for (uint j = 1; j < member->num_preds(); j++) {
1517 nloop->push_pred(member, j, worklist, _bbs);
1518 }
1519 }
1520 }
1521 }
1522 }
1523 }
1524
1525 // Create a member list for each loop consisting
1526 // of both blocks and (immediate child) loops.
1527 for (uint i = 0; i < _num_blocks; i++) {
1528 Block *b = _blocks[i];
1529 CFGLoop* lp = b->_loop;
1530 if (lp == NULL) {
1531 // Not assigned to a loop. Add it to the method's pseudo loop.
1532 b->_loop = root_loop;
1533 lp = root_loop;
1534 }
1535 if (lp == root_loop || b != lp->head()) { // loop heads are already members
1536 lp->add_member(b);
1537 }
1538 if (lp != root_loop) {
1539 if (lp->parent() == NULL) {
1540 // Not a nested loop. Make it a child of the method's pseudo loop.
1541 root_loop->add_nested_loop(lp);
1542 }
1543 if (b == lp->head()) {
1544 // Add nested loop to member list of parent loop.
1545 lp->parent()->add_member(lp);
1546 }
1547 }
1548 }
1549
1550 return root_loop;
1551 }
1552
1553 //------------------------------push_pred--------------------------------------
1554 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) {
1555 Node* pred_n = blk->pred(i);
1556 Block* pred = node_to_blk[pred_n->_idx];
1557 CFGLoop *pred_loop = pred->_loop;
1558 if (pred_loop == NULL) {
1559 // Filter out blocks for non-single-entry loops.
1560 // For all reasonable loops, the head occurs before the tail in RPO.
1561 if (pred->_rpo > head()->_rpo) {
1562 pred->_loop = this;
1563 worklist.push(pred);
1564 }
1565 } else if (pred_loop != this) {
1566 // Nested loop.
1567 while (pred_loop->_parent != NULL && pred_loop->_parent != this) {
1568 pred_loop = pred_loop->_parent;
1569 }
1570 // Make pred's loop be a child
1571 if (pred_loop->_parent == NULL) {
1572 add_nested_loop(pred_loop);
1573 // Continue with loop entry predecessor.
1574 Block* pred_head = pred_loop->head();
1575 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors");
1576 assert(pred_head != head(), "loop head in only one loop");
1577 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk);
1578 } else {
1579 assert(pred_loop->_parent == this && _parent == NULL, "just checking");
1580 }
1581 }
1582 }
1583
1584 //------------------------------add_nested_loop--------------------------------
1585 // Make cl a child of the current loop in the loop tree.
1586 void CFGLoop::add_nested_loop(CFGLoop* cl) {
1587 assert(_parent == NULL, "no parent yet");
1588 assert(cl != this, "not my own parent");
1589 cl->_parent = this;
1590 CFGLoop* ch = _child;
1591 if (ch == NULL) {
1592 _child = cl;
1593 } else {
1594 while (ch->_sibling != NULL) { ch = ch->_sibling; }
1595 ch->_sibling = cl;
1596 }
1597 }
1598
1599 //------------------------------compute_loop_depth-----------------------------
1600 // Store the loop depth in each CFGLoop object.
1601 // Recursively walk the children to do the same for them.
1602 void CFGLoop::compute_loop_depth(int depth) {
1603 _depth = depth;
1604 CFGLoop* ch = _child;
1605 while (ch != NULL) {
1606 ch->compute_loop_depth(depth + 1);
1607 ch = ch->_sibling;
1608 }
1609 }
1610
1611 //------------------------------compute_freq-----------------------------------
1612 // Compute the frequency of each block and loop, relative to a single entry
1613 // into the dominating loop head.
1614 void CFGLoop::compute_freq() {
1615 // Bottom up traversal of loop tree (visit inner loops first.)
1616 // Set loop head frequency to 1.0, then transitively
1617 // compute frequency for all successors in the loop,
1618 // as well as for each exit edge. Inner loops are
1619 // treated as single blocks with loop exit targets
1620 // as the successor blocks.
1621
1622 // Nested loops first
1623 CFGLoop* ch = _child;
1624 while (ch != NULL) {
1625 ch->compute_freq();
1626 ch = ch->_sibling;
1627 }
1628 assert (_members.length() > 0, "no empty loops");
1629 Block* hd = head();
1630 hd->_freq = 1.0f;
1631 for (int i = 0; i < _members.length(); i++) {
1632 CFGElement* s = _members.at(i);
1633 float freq = s->_freq;
1634 if (s->is_block()) {
1635 Block* b = s->as_Block();
1636 for (uint j = 0; j < b->_num_succs; j++) {
1637 Block* sb = b->_succs[j];
1638 update_succ_freq(sb, freq * b->succ_prob(j));
1639 }
1640 } else {
1641 CFGLoop* lp = s->as_CFGLoop();
1642 assert(lp->_parent == this, "immediate child");
1643 for (int k = 0; k < lp->_exits.length(); k++) {
1644 Block* eb = lp->_exits.at(k).get_target();
1645 float prob = lp->_exits.at(k).get_prob();
1646 update_succ_freq(eb, freq * prob);
1647 }
1648 }
1649 }
1650
1651 // For all loops other than the outer, "method" loop,
1652 // sum and normalize the exit probability. The "method" loop
1653 // should keep the initial exit probability of 1, so that
1654 // inner blocks do not get erroneously scaled.
1655 if (_depth != 0) {
1656 // Total the exit probabilities for this loop.
1657 float exits_sum = 0.0f;
1658 for (int i = 0; i < _exits.length(); i++) {
1659 exits_sum += _exits.at(i).get_prob();
1660 }
1661
1662 // Normalize the exit probabilities. Until now, the
1663 // probabilities estimate the possibility of exit per
1664 // a single loop iteration; afterward, they estimate
1665 // the probability of exit per loop entry.
1666 for (int i = 0; i < _exits.length(); i++) {
1667 Block* et = _exits.at(i).get_target();
1668 float new_prob = 0.0f;
1669 if (_exits.at(i).get_prob() > 0.0f) {
1670 new_prob = _exits.at(i).get_prob() / exits_sum;
1671 }
1672 BlockProbPair bpp(et, new_prob);
1673 _exits.at_put(i, bpp);
1674 }
1675
1676 // Save the total, but guard against unreasonable probability,
1677 // as the value is used to estimate the loop trip count.
1678 // An infinite trip count would blur relative block
1679 // frequencies.
1680 if (exits_sum > 1.0f) exits_sum = 1.0;
1681 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN;
1682 _exit_prob = exits_sum;
1683 }
1684 }
1685
1686 //------------------------------succ_prob-------------------------------------
1687 // Determine the probability of reaching successor 'i' from the receiver block.
1688 float Block::succ_prob(uint i) {
1689 int eidx = end_idx();
1690 Node *n = _nodes[eidx]; // Get ending Node
1691
1692 int op = n->Opcode();
1693 if (n->is_Mach()) {
1694 if (n->is_MachNullCheck()) {
1695 // Can only reach here if called after lcm. The original Op_If is gone,
1696 // so we attempt to infer the probability from one or both of the
1697 // successor blocks.
1698 assert(_num_succs == 2, "expecting 2 successors of a null check");
1699 // If either successor has only one predecessor, then the
1700 // probability estimate can be derived using the
1701 // relative frequency of the successor and this block.
1702 if (_succs[i]->num_preds() == 2) {
1703 return _succs[i]->_freq / _freq;
1704 } else if (_succs[1-i]->num_preds() == 2) {
1705 return 1 - (_succs[1-i]->_freq / _freq);
1706 } else {
1707 // Estimate using both successor frequencies
1708 float freq = _succs[i]->_freq;
1709 return freq / (freq + _succs[1-i]->_freq);
1710 }
1711 }
1712 op = n->as_Mach()->ideal_Opcode();
1713 }
1714
1715
1716 // Switch on branch type
1717 switch( op ) {
1718 case Op_CountedLoopEnd:
1719 case Op_If: {
1720 assert (i < 2, "just checking");
1721 // Conditionals pass on only part of their frequency
1722 float prob = n->as_MachIf()->_prob;
1723 assert(prob >= 0.0 && prob <= 1.0, "out of range probability");
1724 // If succ[i] is the FALSE branch, invert path info
1725 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) {
1726 return 1.0f - prob; // not taken
1727 } else {
1728 return prob; // taken
1729 }
1730 }
1731
1732 case Op_Jump:
1733 // Divide the frequency between all successors evenly
1734 return 1.0f/_num_succs;
1735
1736 case Op_Catch: {
1737 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1738 if (ci->_con == CatchProjNode::fall_through_index) {
1739 // Fall-thru path gets the lion's share.
1740 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs;
1741 } else {
1742 // Presume exceptional paths are equally unlikely
1743 return PROB_UNLIKELY_MAG(5);
1744 }
1745 }
1746
1747 case Op_Root:
1748 case Op_Goto:
1749 // Pass frequency straight thru to target
1750 return 1.0f;
1751
1752 case Op_NeverBranch:
1753 return 0.0f;
1754
1755 case Op_TailCall:
1756 case Op_TailJump:
1757 case Op_Return:
1758 case Op_Halt:
1759 case Op_Rethrow:
1760 // Do not push out freq to root block
1761 return 0.0f;
1762
1763 default:
1764 ShouldNotReachHere();
1765 }
1766
1767 return 0.0f;
1768 }
1769
1770 //------------------------------num_fall_throughs-----------------------------
1771 // Return the number of fall-through candidates for a block
1772 int Block::num_fall_throughs() {
1773 int eidx = end_idx();
1774 Node *n = _nodes[eidx]; // Get ending Node
1775
1776 int op = n->Opcode();
1777 if (n->is_Mach()) {
1778 if (n->is_MachNullCheck()) {
1779 // In theory, either side can fall-thru, for simplicity sake,
1780 // let's say only the false branch can now.
1781 return 1;
1782 }
1783 op = n->as_Mach()->ideal_Opcode();
1784 }
1785
1786 // Switch on branch type
1787 switch( op ) {
1788 case Op_CountedLoopEnd:
1789 case Op_If:
1790 return 2;
1791
1792 case Op_Root:
1793 case Op_Goto:
1794 return 1;
1795
1796 case Op_Catch: {
1797 for (uint i = 0; i < _num_succs; i++) {
1798 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1799 if (ci->_con == CatchProjNode::fall_through_index) {
1800 return 1;
1801 }
1802 }
1803 return 0;
1804 }
1805
1806 case Op_Jump:
1807 case Op_NeverBranch:
1808 case Op_TailCall:
1809 case Op_TailJump:
1810 case Op_Return:
1811 case Op_Halt:
1812 case Op_Rethrow:
1813 return 0;
1814
1815 default:
1816 ShouldNotReachHere();
1817 }
1818
1819 return 0;
1820 }
1821
1822 //------------------------------succ_fall_through-----------------------------
1823 // Return true if a specific successor could be fall-through target.
1824 bool Block::succ_fall_through(uint i) {
1825 int eidx = end_idx();
1826 Node *n = _nodes[eidx]; // Get ending Node
1827
1828 int op = n->Opcode();
1829 if (n->is_Mach()) {
1830 if (n->is_MachNullCheck()) {
1831 // In theory, either side can fall-thru, for simplicity sake,
1832 // let's say only the false branch can now.
1833 return _nodes[i + eidx + 1]->Opcode() == Op_IfFalse;
1834 }
1835 op = n->as_Mach()->ideal_Opcode();
1836 }
1837
1838 // Switch on branch type
1839 switch( op ) {
1840 case Op_CountedLoopEnd:
1841 case Op_If:
1842 case Op_Root:
1843 case Op_Goto:
1844 return true;
1845
1846 case Op_Catch: {
1847 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj();
1848 return ci->_con == CatchProjNode::fall_through_index;
1849 }
1850
1851 case Op_Jump:
1852 case Op_NeverBranch:
1853 case Op_TailCall:
1854 case Op_TailJump:
1855 case Op_Return:
1856 case Op_Halt:
1857 case Op_Rethrow:
1858 return false;
1859
1860 default:
1861 ShouldNotReachHere();
1862 }
1863
1864 return false;
1865 }
1866
1867 //------------------------------update_uncommon_branch------------------------
1868 // Update the probability of a two-branch to be uncommon
1869 void Block::update_uncommon_branch(Block* ub) {
1870 int eidx = end_idx();
1871 Node *n = _nodes[eidx]; // Get ending Node
1872
1873 int op = n->as_Mach()->ideal_Opcode();
1874
1875 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If");
1876 assert(num_fall_throughs() == 2, "must be a two way branch block");
1877
1878 // Which successor is ub?
1879 uint s;
1880 for (s = 0; s <_num_succs; s++) {
1881 if (_succs[s] == ub) break;
1882 }
1883 assert(s < 2, "uncommon successor must be found");
1884
1885 // If ub is the true path, make the proability small, else
1886 // ub is the false path, and make the probability large
1887 bool invert = (_nodes[s + eidx + 1]->Opcode() == Op_IfFalse);
1888
1889 // Get existing probability
1890 float p = n->as_MachIf()->_prob;
1891
1892 if (invert) p = 1.0 - p;
1893 if (p > PROB_MIN) {
1894 p = PROB_MIN;
1895 }
1896 if (invert) p = 1.0 - p;
1897
1898 n->as_MachIf()->_prob = p;
1899 }
1900
1901 //------------------------------update_succ_freq-------------------------------
1902 // Update the appropriate frequency associated with block 'b', a successor of
1903 // a block in this loop.
1904 void CFGLoop::update_succ_freq(Block* b, float freq) {
1905 if (b->_loop == this) {
1906 if (b == head()) {
1907 // back branch within the loop
1908 // Do nothing now, the loop carried frequency will be
1909 // adjust later in scale_freq().
1910 } else {
1911 // simple branch within the loop
1912 b->_freq += freq;
1913 }
1914 } else if (!in_loop_nest(b)) {
1915 // branch is exit from this loop
1916 BlockProbPair bpp(b, freq);
1917 _exits.append(bpp);
1918 } else {
1919 // branch into nested loop
1920 CFGLoop* ch = b->_loop;
1921 ch->_freq += freq;
1922 }
1923 }
1924
1925 //------------------------------in_loop_nest-----------------------------------
1926 // Determine if block b is in the receiver's loop nest.
1927 bool CFGLoop::in_loop_nest(Block* b) {
1928 int depth = _depth;
1929 CFGLoop* b_loop = b->_loop;
1930 int b_depth = b_loop->_depth;
1931 if (depth == b_depth) {
1932 return true;
1933 }
1934 while (b_depth > depth) {
1935 b_loop = b_loop->_parent;
1936 b_depth = b_loop->_depth;
1937 }
1938 return b_loop == this;
1939 }
1940
1941 //------------------------------scale_freq-------------------------------------
1942 // Scale frequency of loops and blocks by trip counts from outer loops
1943 // Do a top down traversal of loop tree (visit outer loops first.)
1944 void CFGLoop::scale_freq() {
1945 float loop_freq = _freq * trip_count();
1946 _freq = loop_freq;
1947 for (int i = 0; i < _members.length(); i++) {
1948 CFGElement* s = _members.at(i);
1949 float block_freq = s->_freq * loop_freq;
1950 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY)
1951 block_freq = MIN_BLOCK_FREQUENCY;
1952 s->_freq = block_freq;
1953 }
1954 CFGLoop* ch = _child;
1955 while (ch != NULL) {
1956 ch->scale_freq();
1957 ch = ch->_sibling;
1958 }
1959 }
1960
1961 // Frequency of outer loop
1962 float CFGLoop::outer_loop_freq() const {
1963 if (_child != NULL) {
1964 return _child->_freq;
1965 }
1966 return _freq;
1967 }
1968
1969 #ifndef PRODUCT
1970 //------------------------------dump_tree--------------------------------------
1971 void CFGLoop::dump_tree() const {
1972 dump();
1973 if (_child != NULL) _child->dump_tree();
1974 if (_sibling != NULL) _sibling->dump_tree();
1975 }
1976
1977 //------------------------------dump-------------------------------------------
1978 void CFGLoop::dump() const {
1979 for (int i = 0; i < _depth; i++) tty->print(" ");
1980 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n",
1981 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq);
1982 for (int i = 0; i < _depth; i++) tty->print(" ");
1983 tty->print(" members:", _id);
1984 int k = 0;
1985 for (int i = 0; i < _members.length(); i++) {
1986 if (k++ >= 6) {
1987 tty->print("\n ");
1988 for (int j = 0; j < _depth+1; j++) tty->print(" ");
1989 k = 0;
1990 }
1991 CFGElement *s = _members.at(i);
1992 if (s->is_block()) {
1993 Block *b = s->as_Block();
1994 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq);
1995 } else {
1996 CFGLoop* lp = s->as_CFGLoop();
1997 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq);
1998 }
1999 }
2000 tty->print("\n");
2001 for (int i = 0; i < _depth; i++) tty->print(" ");
2002 tty->print(" exits: ");
2003 k = 0;
2004 for (int i = 0; i < _exits.length(); i++) {
2005 if (k++ >= 7) {
2006 tty->print("\n ");
2007 for (int j = 0; j < _depth+1; j++) tty->print(" ");
2008 k = 0;
2009 }
2010 Block *blk = _exits.at(i).get_target();
2011 float prob = _exits.at(i).get_prob();
2012 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100));
2013 }
2014 tty->print("\n");
2015 }
2016 #endif