Mercurial > hg > graal-compiler
annotate src/share/vm/opto/gcm.cpp @ 404:78c058bc5cdc
6717150: improper constant folding of subnormal strictfp multiplications and divides
Summary: suppress constant folding of double divides and multiplications on ia32
Reviewed-by: never
author | rasbold |
---|---|
date | Tue, 14 Oct 2008 06:58:58 -0700 |
parents | 756b58154237 |
children | 72c5366e5d86 |
rev | line source |
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0 | 1 /* |
196 | 2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // Portions of code courtesy of Clifford Click | |
26 | |
27 // Optimization - Graph Style | |
28 | |
29 #include "incls/_precompiled.incl" | |
30 #include "incls/_gcm.cpp.incl" | |
31 | |
32 //----------------------------schedule_node_into_block------------------------- | |
33 // Insert node n into block b. Look for projections of n and make sure they | |
34 // are in b also. | |
35 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) { | |
36 // Set basic block of n, Add n to b, | |
37 _bbs.map(n->_idx, b); | |
38 b->add_inst(n); | |
39 | |
40 // After Matching, nearly any old Node may have projections trailing it. | |
41 // These are usually machine-dependent flags. In any case, they might | |
42 // float to another block below this one. Move them up. | |
43 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
44 Node* use = n->fast_out(i); | |
45 if (use->is_Proj()) { | |
46 Block* buse = _bbs[use->_idx]; | |
47 if (buse != b) { // In wrong block? | |
48 if (buse != NULL) | |
49 buse->find_remove(use); // Remove from wrong block | |
50 _bbs.map(use->_idx, b); // Re-insert in this block | |
51 b->add_inst(use); | |
52 } | |
53 } | |
54 } | |
55 } | |
56 | |
57 | |
58 //------------------------------schedule_pinned_nodes-------------------------- | |
59 // Set the basic block for Nodes pinned into blocks | |
60 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) { | |
61 // Allocate node stack of size C->unique()+8 to avoid frequent realloc | |
62 GrowableArray <Node *> spstack(C->unique()+8); | |
63 spstack.push(_root); | |
64 while ( spstack.is_nonempty() ) { | |
65 Node *n = spstack.pop(); | |
66 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited | |
67 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down! | |
68 Node *input = n->in(0); | |
69 assert( input, "pinned Node must have Control" ); | |
70 while( !input->is_block_start() ) | |
71 input = input->in(0); | |
72 Block *b = _bbs[input->_idx]; // Basic block of controlling input | |
73 schedule_node_into_block(n, b); | |
74 } | |
75 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs | |
76 if( n->in(i) != NULL ) | |
77 spstack.push(n->in(i)); | |
78 } | |
79 } | |
80 } | |
81 } | |
82 | |
83 #ifdef ASSERT | |
84 // Assert that new input b2 is dominated by all previous inputs. | |
85 // Check this by by seeing that it is dominated by b1, the deepest | |
86 // input observed until b2. | |
87 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) { | |
88 if (b1 == NULL) return; | |
89 assert(b1->_dom_depth < b2->_dom_depth, "sanity"); | |
90 Block* tmp = b2; | |
91 while (tmp != b1 && tmp != NULL) { | |
92 tmp = tmp->_idom; | |
93 } | |
94 if (tmp != b1) { | |
95 // Detected an unschedulable graph. Print some nice stuff and die. | |
96 tty->print_cr("!!! Unschedulable graph !!!"); | |
97 for (uint j=0; j<n->len(); j++) { // For all inputs | |
98 Node* inn = n->in(j); // Get input | |
99 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
100 Block* inb = bbs[inn->_idx]; | |
101 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order, | |
102 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth); | |
103 inn->dump(); | |
104 } | |
105 tty->print("Failing node: "); | |
106 n->dump(); | |
107 assert(false, "unscheduable graph"); | |
108 } | |
109 } | |
110 #endif | |
111 | |
112 static Block* find_deepest_input(Node* n, Block_Array &bbs) { | |
113 // Find the last input dominated by all other inputs. | |
114 Block* deepb = NULL; // Deepest block so far | |
115 int deepb_dom_depth = 0; | |
116 for (uint k = 0; k < n->len(); k++) { // For all inputs | |
117 Node* inn = n->in(k); // Get input | |
118 if (inn == NULL) continue; // Ignore NULL, missing inputs | |
119 Block* inb = bbs[inn->_idx]; | |
120 assert(inb != NULL, "must already have scheduled this input"); | |
121 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
122 // The new inb must be dominated by the previous deepb. | |
123 // The various inputs must be linearly ordered in the dom | |
124 // tree, or else there will not be a unique deepest block. | |
125 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs)); | |
126 deepb = inb; // Save deepest block | |
127 deepb_dom_depth = deepb->_dom_depth; | |
128 } | |
129 } | |
130 assert(deepb != NULL, "must be at least one input to n"); | |
131 return deepb; | |
132 } | |
133 | |
134 | |
135 //------------------------------schedule_early--------------------------------- | |
136 // Find the earliest Block any instruction can be placed in. Some instructions | |
137 // are pinned into Blocks. Unpinned instructions can appear in last block in | |
138 // which all their inputs occur. | |
139 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) { | |
140 // Allocate stack with enough space to avoid frequent realloc | |
141 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats | |
142 // roots.push(_root); _root will be processed among C->top() inputs | |
143 roots.push(C->top()); | |
144 visited.set(C->top()->_idx); | |
145 | |
146 while (roots.size() != 0) { | |
147 // Use local variables nstack_top_n & nstack_top_i to cache values | |
148 // on stack's top. | |
149 Node *nstack_top_n = roots.pop(); | |
150 uint nstack_top_i = 0; | |
151 //while_nstack_nonempty: | |
152 while (true) { | |
153 // Get parent node and next input's index from stack's top. | |
154 Node *n = nstack_top_n; | |
155 uint i = nstack_top_i; | |
156 | |
157 if (i == 0) { | |
158 // Special control input processing. | |
159 // While I am here, go ahead and look for Nodes which are taking control | |
160 // from a is_block_proj Node. After I inserted RegionNodes to make proper | |
161 // blocks, the control at a is_block_proj more properly comes from the | |
162 // Region being controlled by the block_proj Node. | |
163 const Node *in0 = n->in(0); | |
164 if (in0 != NULL) { // Control-dependent? | |
165 const Node *p = in0->is_block_proj(); | |
166 if (p != NULL && p != n) { // Control from a block projection? | |
167 // Find trailing Region | |
168 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block | |
169 uint j = 0; | |
170 if (pb->_num_succs != 1) { // More then 1 successor? | |
171 // Search for successor | |
172 uint max = pb->_nodes.size(); | |
173 assert( max > 1, "" ); | |
174 uint start = max - pb->_num_succs; | |
175 // Find which output path belongs to projection | |
176 for (j = start; j < max; j++) { | |
177 if( pb->_nodes[j] == in0 ) | |
178 break; | |
179 } | |
180 assert( j < max, "must find" ); | |
181 // Change control to match head of successor basic block | |
182 j -= start; | |
183 } | |
184 n->set_req(0, pb->_succs[j]->head()); | |
185 } | |
186 } else { // n->in(0) == NULL | |
187 if (n->req() == 1) { // This guy is a constant with NO inputs? | |
188 n->set_req(0, _root); | |
189 } | |
190 } | |
191 } | |
192 | |
193 // First, visit all inputs and force them to get a block. If an | |
194 // input is already in a block we quit following inputs (to avoid | |
195 // cycles). Instead we put that Node on a worklist to be handled | |
196 // later (since IT'S inputs may not have a block yet). | |
197 bool done = true; // Assume all n's inputs will be processed | |
198 while (i < n->len()) { // For all inputs | |
199 Node *in = n->in(i); // Get input | |
200 ++i; | |
201 if (in == NULL) continue; // Ignore NULL, missing inputs | |
202 int is_visited = visited.test_set(in->_idx); | |
203 if (!_bbs.lookup(in->_idx)) { // Missing block selection? | |
204 if (is_visited) { | |
205 // assert( !visited.test(in->_idx), "did not schedule early" ); | |
206 return false; | |
207 } | |
208 nstack.push(n, i); // Save parent node and next input's index. | |
209 nstack_top_n = in; // Process current input now. | |
210 nstack_top_i = 0; | |
211 done = false; // Not all n's inputs processed. | |
212 break; // continue while_nstack_nonempty; | |
213 } else if (!is_visited) { // Input not yet visited? | |
214 roots.push(in); // Visit this guy later, using worklist | |
215 } | |
216 } | |
217 if (done) { | |
218 // All of n's inputs have been processed, complete post-processing. | |
219 | |
220 // Some instructions are pinned into a block. These include Region, | |
221 // Phi, Start, Return, and other control-dependent instructions and | |
222 // any projections which depend on them. | |
223 if (!n->pinned()) { | |
224 // Set earliest legal block. | |
225 _bbs.map(n->_idx, find_deepest_input(n, _bbs)); | |
226 } | |
227 | |
228 if (nstack.is_empty()) { | |
229 // Finished all nodes on stack. | |
230 // Process next node on the worklist 'roots'. | |
231 break; | |
232 } | |
233 // Get saved parent node and next input's index. | |
234 nstack_top_n = nstack.node(); | |
235 nstack_top_i = nstack.index(); | |
236 nstack.pop(); | |
237 } // if (done) | |
238 } // while (true) | |
239 } // while (roots.size() != 0) | |
240 return true; | |
241 } | |
242 | |
243 //------------------------------dom_lca---------------------------------------- | |
244 // Find least common ancestor in dominator tree | |
245 // LCA is a current notion of LCA, to be raised above 'this'. | |
246 // As a convenient boundary condition, return 'this' if LCA is NULL. | |
247 // Find the LCA of those two nodes. | |
248 Block* Block::dom_lca(Block* LCA) { | |
249 if (LCA == NULL || LCA == this) return this; | |
250 | |
251 Block* anc = this; | |
252 while (anc->_dom_depth > LCA->_dom_depth) | |
253 anc = anc->_idom; // Walk up till anc is as high as LCA | |
254 | |
255 while (LCA->_dom_depth > anc->_dom_depth) | |
256 LCA = LCA->_idom; // Walk up till LCA is as high as anc | |
257 | |
258 while (LCA != anc) { // Walk both up till they are the same | |
259 LCA = LCA->_idom; | |
260 anc = anc->_idom; | |
261 } | |
262 | |
263 return LCA; | |
264 } | |
265 | |
266 //--------------------------raise_LCA_above_use-------------------------------- | |
267 // We are placing a definition, and have been given a def->use edge. | |
268 // The definition must dominate the use, so move the LCA upward in the | |
269 // dominator tree to dominate the use. If the use is a phi, adjust | |
270 // the LCA only with the phi input paths which actually use this def. | |
271 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) { | |
272 Block* buse = bbs[use->_idx]; | |
273 if (buse == NULL) return LCA; // Unused killing Projs have no use block | |
274 if (!use->is_Phi()) return buse->dom_lca(LCA); | |
275 uint pmax = use->req(); // Number of Phi inputs | |
276 // Why does not this loop just break after finding the matching input to | |
277 // the Phi? Well...it's like this. I do not have true def-use/use-def | |
278 // chains. Means I cannot distinguish, from the def-use direction, which | |
279 // of many use-defs lead from the same use to the same def. That is, this | |
280 // Phi might have several uses of the same def. Each use appears in a | |
281 // different predecessor block. But when I enter here, I cannot distinguish | |
282 // which use-def edge I should find the predecessor block for. So I find | |
283 // them all. Means I do a little extra work if a Phi uses the same value | |
284 // more than once. | |
285 for (uint j=1; j<pmax; j++) { // For all inputs | |
286 if (use->in(j) == def) { // Found matching input? | |
287 Block* pred = bbs[buse->pred(j)->_idx]; | |
288 LCA = pred->dom_lca(LCA); | |
289 } | |
290 } | |
291 return LCA; | |
292 } | |
293 | |
294 //----------------------------raise_LCA_above_marks---------------------------- | |
295 // Return a new LCA that dominates LCA and any of its marked predecessors. | |
296 // Search all my parents up to 'early' (exclusive), looking for predecessors | |
297 // which are marked with the given index. Return the LCA (in the dom tree) | |
298 // of all marked blocks. If there are none marked, return the original | |
299 // LCA. | |
300 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, | |
301 Block* early, Block_Array &bbs) { | |
302 Block_List worklist; | |
303 worklist.push(LCA); | |
304 while (worklist.size() > 0) { | |
305 Block* mid = worklist.pop(); | |
306 if (mid == early) continue; // stop searching here | |
307 | |
308 // Test and set the visited bit. | |
309 if (mid->raise_LCA_visited() == mark) continue; // already visited | |
310 | |
311 // Don't process the current LCA, otherwise the search may terminate early | |
312 if (mid != LCA && mid->raise_LCA_mark() == mark) { | |
313 // Raise the LCA. | |
314 LCA = mid->dom_lca(LCA); | |
315 if (LCA == early) break; // stop searching everywhere | |
316 assert(early->dominates(LCA), "early is high enough"); | |
317 // Resume searching at that point, skipping intermediate levels. | |
318 worklist.push(LCA); | |
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319 if (LCA == mid) |
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320 continue; // Don't mark as visited to avoid early termination. |
0 | 321 } else { |
322 // Keep searching through this block's predecessors. | |
323 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { | |
324 Block* mid_parent = bbs[ mid->pred(j)->_idx ]; | |
325 worklist.push(mid_parent); | |
326 } | |
327 } | |
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328 mid->set_raise_LCA_visited(mark); |
0 | 329 } |
330 return LCA; | |
331 } | |
332 | |
333 //--------------------------memory_early_block-------------------------------- | |
334 // This is a variation of find_deepest_input, the heart of schedule_early. | |
335 // Find the "early" block for a load, if we considered only memory and | |
336 // address inputs, that is, if other data inputs were ignored. | |
337 // | |
338 // Because a subset of edges are considered, the resulting block will | |
339 // be earlier (at a shallower dom_depth) than the true schedule_early | |
340 // point of the node. We compute this earlier block as a more permissive | |
341 // site for anti-dependency insertion, but only if subsume_loads is enabled. | |
342 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) { | |
343 Node* base; | |
344 Node* index; | |
345 Node* store = load->in(MemNode::Memory); | |
346 load->as_Mach()->memory_inputs(base, index); | |
347 | |
348 assert(base != NodeSentinel && index != NodeSentinel, | |
349 "unexpected base/index inputs"); | |
350 | |
351 Node* mem_inputs[4]; | |
352 int mem_inputs_length = 0; | |
353 if (base != NULL) mem_inputs[mem_inputs_length++] = base; | |
354 if (index != NULL) mem_inputs[mem_inputs_length++] = index; | |
355 if (store != NULL) mem_inputs[mem_inputs_length++] = store; | |
356 | |
357 // In the comparision below, add one to account for the control input, | |
358 // which may be null, but always takes up a spot in the in array. | |
359 if (mem_inputs_length + 1 < (int) load->req()) { | |
360 // This "load" has more inputs than just the memory, base and index inputs. | |
361 // For purposes of checking anti-dependences, we need to start | |
362 // from the early block of only the address portion of the instruction, | |
363 // and ignore other blocks that may have factored into the wider | |
364 // schedule_early calculation. | |
365 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0); | |
366 | |
367 Block* deepb = NULL; // Deepest block so far | |
368 int deepb_dom_depth = 0; | |
369 for (int i = 0; i < mem_inputs_length; i++) { | |
370 Block* inb = bbs[mem_inputs[i]->_idx]; | |
371 if (deepb_dom_depth < (int) inb->_dom_depth) { | |
372 // The new inb must be dominated by the previous deepb. | |
373 // The various inputs must be linearly ordered in the dom | |
374 // tree, or else there will not be a unique deepest block. | |
375 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs)); | |
376 deepb = inb; // Save deepest block | |
377 deepb_dom_depth = deepb->_dom_depth; | |
378 } | |
379 } | |
380 early = deepb; | |
381 } | |
382 | |
383 return early; | |
384 } | |
385 | |
386 //--------------------------insert_anti_dependences--------------------------- | |
387 // A load may need to witness memory that nearby stores can overwrite. | |
388 // For each nearby store, either insert an "anti-dependence" edge | |
389 // from the load to the store, or else move LCA upward to force the | |
390 // load to (eventually) be scheduled in a block above the store. | |
391 // | |
392 // Do not add edges to stores on distinct control-flow paths; | |
393 // only add edges to stores which might interfere. | |
394 // | |
395 // Return the (updated) LCA. There will not be any possibly interfering | |
396 // store between the load's "early block" and the updated LCA. | |
397 // Any stores in the updated LCA will have new precedence edges | |
398 // back to the load. The caller is expected to schedule the load | |
399 // in the LCA, in which case the precedence edges will make LCM | |
400 // preserve anti-dependences. The caller may also hoist the load | |
401 // above the LCA, if it is not the early block. | |
402 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) { | |
403 assert(load->needs_anti_dependence_check(), "must be a load of some sort"); | |
404 assert(LCA != NULL, ""); | |
405 DEBUG_ONLY(Block* LCA_orig = LCA); | |
406 | |
407 // Compute the alias index. Loads and stores with different alias indices | |
408 // do not need anti-dependence edges. | |
409 uint load_alias_idx = C->get_alias_index(load->adr_type()); | |
410 #ifdef ASSERT | |
411 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 && | |
412 (PrintOpto || VerifyAliases || | |
413 PrintMiscellaneous && (WizardMode || Verbose))) { | |
414 // Load nodes should not consume all of memory. | |
415 // Reporting a bottom type indicates a bug in adlc. | |
416 // If some particular type of node validly consumes all of memory, | |
417 // sharpen the preceding "if" to exclude it, so we can catch bugs here. | |
418 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory."); | |
419 load->dump(2); | |
420 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, ""); | |
421 } | |
422 #endif | |
423 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp), | |
424 "String compare is only known 'load' that does not conflict with any stores"); | |
425 | |
426 if (!C->alias_type(load_alias_idx)->is_rewritable()) { | |
427 // It is impossible to spoil this load by putting stores before it, | |
428 // because we know that the stores will never update the value | |
429 // which 'load' must witness. | |
430 return LCA; | |
431 } | |
432 | |
433 node_idx_t load_index = load->_idx; | |
434 | |
435 // Note the earliest legal placement of 'load', as determined by | |
436 // by the unique point in the dom tree where all memory effects | |
437 // and other inputs are first available. (Computed by schedule_early.) | |
438 // For normal loads, 'early' is the shallowest place (dom graph wise) | |
439 // to look for anti-deps between this load and any store. | |
440 Block* early = _bbs[load_index]; | |
441 | |
442 // If we are subsuming loads, compute an "early" block that only considers | |
443 // memory or address inputs. This block may be different than the | |
444 // schedule_early block in that it could be at an even shallower depth in the | |
445 // dominator tree, and allow for a broader discovery of anti-dependences. | |
446 if (C->subsume_loads()) { | |
447 early = memory_early_block(load, early, _bbs); | |
448 } | |
449 | |
450 ResourceArea *area = Thread::current()->resource_area(); | |
451 Node_List worklist_mem(area); // prior memory state to store | |
452 Node_List worklist_store(area); // possible-def to explore | |
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453 Node_List worklist_visited(area); // visited mergemem nodes |
0 | 454 Node_List non_early_stores(area); // all relevant stores outside of early |
455 bool must_raise_LCA = false; | |
456 | |
457 #ifdef TRACK_PHI_INPUTS | |
458 // %%% This extra checking fails because MergeMem nodes are not GVNed. | |
459 // Provide "phi_inputs" to check if every input to a PhiNode is from the | |
460 // original memory state. This indicates a PhiNode for which should not | |
461 // prevent the load from sinking. For such a block, set_raise_LCA_mark | |
462 // may be overly conservative. | |
463 // Mechanism: count inputs seen for each Phi encountered in worklist_store. | |
464 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0)); | |
465 #endif | |
466 | |
467 // 'load' uses some memory state; look for users of the same state. | |
468 // Recurse through MergeMem nodes to the stores that use them. | |
469 | |
470 // Each of these stores is a possible definition of memory | |
471 // that 'load' needs to use. We need to force 'load' | |
472 // to occur before each such store. When the store is in | |
473 // the same block as 'load', we insert an anti-dependence | |
474 // edge load->store. | |
475 | |
476 // The relevant stores "nearby" the load consist of a tree rooted | |
477 // at initial_mem, with internal nodes of type MergeMem. | |
478 // Therefore, the branches visited by the worklist are of this form: | |
479 // initial_mem -> (MergeMem ->)* store | |
480 // The anti-dependence constraints apply only to the fringe of this tree. | |
481 | |
482 Node* initial_mem = load->in(MemNode::Memory); | |
483 worklist_store.push(initial_mem); | |
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484 worklist_visited.push(initial_mem); |
0 | 485 worklist_mem.push(NULL); |
486 while (worklist_store.size() > 0) { | |
487 // Examine a nearby store to see if it might interfere with our load. | |
488 Node* mem = worklist_mem.pop(); | |
489 Node* store = worklist_store.pop(); | |
490 uint op = store->Opcode(); | |
491 | |
492 // MergeMems do not directly have anti-deps. | |
493 // Treat them as internal nodes in a forward tree of memory states, | |
494 // the leaves of which are each a 'possible-def'. | |
495 if (store == initial_mem // root (exclusive) of tree we are searching | |
496 || op == Op_MergeMem // internal node of tree we are searching | |
497 ) { | |
498 mem = store; // It's not a possibly interfering store. | |
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499 if (store == initial_mem) |
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500 initial_mem = NULL; // only process initial memory once |
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501 |
0 | 502 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { |
503 store = mem->fast_out(i); | |
504 if (store->is_MergeMem()) { | |
505 // Be sure we don't get into combinatorial problems. | |
506 // (Allow phis to be repeated; they can merge two relevant states.) | |
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507 uint j = worklist_visited.size(); |
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508 for (; j > 0; j--) { |
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509 if (worklist_visited.at(j-1) == store) break; |
0 | 510 } |
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511 if (j > 0) continue; // already on work list; do not repeat |
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512 worklist_visited.push(store); |
0 | 513 } |
514 worklist_mem.push(mem); | |
515 worklist_store.push(store); | |
516 } | |
517 continue; | |
518 } | |
519 | |
520 if (op == Op_MachProj || op == Op_Catch) continue; | |
521 if (store->needs_anti_dependence_check()) continue; // not really a store | |
522 | |
523 // Compute the alias index. Loads and stores with different alias | |
524 // indices do not need anti-dependence edges. Wide MemBar's are | |
525 // anti-dependent on everything (except immutable memories). | |
526 const TypePtr* adr_type = store->adr_type(); | |
527 if (!C->can_alias(adr_type, load_alias_idx)) continue; | |
528 | |
529 // Most slow-path runtime calls do NOT modify Java memory, but | |
530 // they can block and so write Raw memory. | |
531 if (store->is_Mach()) { | |
532 MachNode* mstore = store->as_Mach(); | |
533 if (load_alias_idx != Compile::AliasIdxRaw) { | |
534 // Check for call into the runtime using the Java calling | |
535 // convention (and from there into a wrapper); it has no | |
536 // _method. Can't do this optimization for Native calls because | |
537 // they CAN write to Java memory. | |
538 if (mstore->ideal_Opcode() == Op_CallStaticJava) { | |
539 assert(mstore->is_MachSafePoint(), ""); | |
540 MachSafePointNode* ms = (MachSafePointNode*) mstore; | |
541 assert(ms->is_MachCallJava(), ""); | |
542 MachCallJavaNode* mcj = (MachCallJavaNode*) ms; | |
543 if (mcj->_method == NULL) { | |
544 // These runtime calls do not write to Java visible memory | |
545 // (other than Raw) and so do not require anti-dependence edges. | |
546 continue; | |
547 } | |
548 } | |
549 // Same for SafePoints: they read/write Raw but only read otherwise. | |
550 // This is basically a workaround for SafePoints only defining control | |
551 // instead of control + memory. | |
552 if (mstore->ideal_Opcode() == Op_SafePoint) | |
553 continue; | |
554 } else { | |
555 // Some raw memory, such as the load of "top" at an allocation, | |
556 // can be control dependent on the previous safepoint. See | |
557 // comments in GraphKit::allocate_heap() about control input. | |
558 // Inserting an anti-dep between such a safepoint and a use | |
559 // creates a cycle, and will cause a subsequent failure in | |
560 // local scheduling. (BugId 4919904) | |
561 // (%%% How can a control input be a safepoint and not a projection??) | |
562 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore) | |
563 continue; | |
564 } | |
565 } | |
566 | |
567 // Identify a block that the current load must be above, | |
568 // or else observe that 'store' is all the way up in the | |
569 // earliest legal block for 'load'. In the latter case, | |
570 // immediately insert an anti-dependence edge. | |
571 Block* store_block = _bbs[store->_idx]; | |
572 assert(store_block != NULL, "unused killing projections skipped above"); | |
573 | |
574 if (store->is_Phi()) { | |
575 // 'load' uses memory which is one (or more) of the Phi's inputs. | |
576 // It must be scheduled not before the Phi, but rather before | |
577 // each of the relevant Phi inputs. | |
578 // | |
579 // Instead of finding the LCA of all inputs to a Phi that match 'mem', | |
580 // we mark each corresponding predecessor block and do a combined | |
581 // hoisting operation later (raise_LCA_above_marks). | |
582 // | |
583 // Do not assert(store_block != early, "Phi merging memory after access") | |
584 // PhiNode may be at start of block 'early' with backedge to 'early' | |
585 DEBUG_ONLY(bool found_match = false); | |
586 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) { | |
587 if (store->in(j) == mem) { // Found matching input? | |
588 DEBUG_ONLY(found_match = true); | |
589 Block* pred_block = _bbs[store_block->pred(j)->_idx]; | |
590 if (pred_block != early) { | |
591 // If any predecessor of the Phi matches the load's "early block", | |
592 // we do not need a precedence edge between the Phi and 'load' | |
593 // since the load will be forced into a block preceeding the Phi. | |
594 pred_block->set_raise_LCA_mark(load_index); | |
595 assert(!LCA_orig->dominates(pred_block) || | |
596 early->dominates(pred_block), "early is high enough"); | |
597 must_raise_LCA = true; | |
598 } | |
599 } | |
600 } | |
601 assert(found_match, "no worklist bug"); | |
602 #ifdef TRACK_PHI_INPUTS | |
603 #ifdef ASSERT | |
604 // This assert asks about correct handling of PhiNodes, which may not | |
605 // have all input edges directly from 'mem'. See BugId 4621264 | |
606 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1; | |
607 // Increment by exactly one even if there are multiple copies of 'mem' | |
608 // coming into the phi, because we will run this block several times | |
609 // if there are several copies of 'mem'. (That's how DU iterators work.) | |
610 phi_inputs.at_put(store->_idx, num_mem_inputs); | |
611 assert(PhiNode::Input + num_mem_inputs < store->req(), | |
612 "Expect at least one phi input will not be from original memory state"); | |
613 #endif //ASSERT | |
614 #endif //TRACK_PHI_INPUTS | |
615 } else if (store_block != early) { | |
616 // 'store' is between the current LCA and earliest possible block. | |
617 // Label its block, and decide later on how to raise the LCA | |
618 // to include the effect on LCA of this store. | |
619 // If this store's block gets chosen as the raised LCA, we | |
620 // will find him on the non_early_stores list and stick him | |
621 // with a precedence edge. | |
622 // (But, don't bother if LCA is already raised all the way.) | |
623 if (LCA != early) { | |
624 store_block->set_raise_LCA_mark(load_index); | |
625 must_raise_LCA = true; | |
626 non_early_stores.push(store); | |
627 } | |
628 } else { | |
629 // Found a possibly-interfering store in the load's 'early' block. | |
630 // This means 'load' cannot sink at all in the dominator tree. | |
631 // Add an anti-dep edge, and squeeze 'load' into the highest block. | |
632 assert(store != load->in(0), "dependence cycle found"); | |
633 if (verify) { | |
634 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
635 } else { | |
636 store->add_prec(load); | |
637 } | |
638 LCA = early; | |
639 // This turns off the process of gathering non_early_stores. | |
640 } | |
641 } | |
642 // (Worklist is now empty; all nearby stores have been visited.) | |
643 | |
644 // Finished if 'load' must be scheduled in its 'early' block. | |
645 // If we found any stores there, they have already been given | |
646 // precedence edges. | |
647 if (LCA == early) return LCA; | |
648 | |
649 // We get here only if there are no possibly-interfering stores | |
650 // in the load's 'early' block. Move LCA up above all predecessors | |
651 // which contain stores we have noted. | |
652 // | |
653 // The raised LCA block can be a home to such interfering stores, | |
654 // but its predecessors must not contain any such stores. | |
655 // | |
656 // The raised LCA will be a lower bound for placing the load, | |
657 // preventing the load from sinking past any block containing | |
658 // a store that may invalidate the memory state required by 'load'. | |
659 if (must_raise_LCA) | |
660 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs); | |
661 if (LCA == early) return LCA; | |
662 | |
663 // Insert anti-dependence edges from 'load' to each store | |
664 // in the non-early LCA block. | |
665 // Mine the non_early_stores list for such stores. | |
666 if (LCA->raise_LCA_mark() == load_index) { | |
667 while (non_early_stores.size() > 0) { | |
668 Node* store = non_early_stores.pop(); | |
669 Block* store_block = _bbs[store->_idx]; | |
670 if (store_block == LCA) { | |
671 // add anti_dependence from store to load in its own block | |
672 assert(store != load->in(0), "dependence cycle found"); | |
673 if (verify) { | |
674 assert(store->find_edge(load) != -1, "missing precedence edge"); | |
675 } else { | |
676 store->add_prec(load); | |
677 } | |
678 } else { | |
679 assert(store_block->raise_LCA_mark() == load_index, "block was marked"); | |
680 // Any other stores we found must be either inside the new LCA | |
681 // or else outside the original LCA. In the latter case, they | |
682 // did not interfere with any use of 'load'. | |
683 assert(LCA->dominates(store_block) | |
684 || !LCA_orig->dominates(store_block), "no stray stores"); | |
685 } | |
686 } | |
687 } | |
688 | |
689 // Return the highest block containing stores; any stores | |
690 // within that block have been given anti-dependence edges. | |
691 return LCA; | |
692 } | |
693 | |
694 // This class is used to iterate backwards over the nodes in the graph. | |
695 | |
696 class Node_Backward_Iterator { | |
697 | |
698 private: | |
699 Node_Backward_Iterator(); | |
700 | |
701 public: | |
702 // Constructor for the iterator | |
703 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs); | |
704 | |
705 // Postincrement operator to iterate over the nodes | |
706 Node *next(); | |
707 | |
708 private: | |
709 VectorSet &_visited; | |
710 Node_List &_stack; | |
711 Block_Array &_bbs; | |
712 }; | |
713 | |
714 // Constructor for the Node_Backward_Iterator | |
715 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs ) | |
716 : _visited(visited), _stack(stack), _bbs(bbs) { | |
717 // The stack should contain exactly the root | |
718 stack.clear(); | |
719 stack.push(root); | |
720 | |
721 // Clear the visited bits | |
722 visited.Clear(); | |
723 } | |
724 | |
725 // Iterator for the Node_Backward_Iterator | |
726 Node *Node_Backward_Iterator::next() { | |
727 | |
728 // If the _stack is empty, then just return NULL: finished. | |
729 if ( !_stack.size() ) | |
730 return NULL; | |
731 | |
732 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been | |
733 // made stateless, so I do not need to record the index 'i' on my _stack. | |
734 // Instead I visit all users each time, scanning for unvisited users. | |
735 // I visit unvisited not-anti-dependence users first, then anti-dependent | |
736 // children next. | |
737 Node *self = _stack.pop(); | |
738 | |
739 // I cycle here when I am entering a deeper level of recursion. | |
740 // The key variable 'self' was set prior to jumping here. | |
741 while( 1 ) { | |
742 | |
743 _visited.set(self->_idx); | |
744 | |
745 // Now schedule all uses as late as possible. | |
746 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx; | |
747 uint src_rpo = _bbs[src]->_rpo; | |
748 | |
749 // Schedule all nodes in a post-order visit | |
750 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any | |
751 | |
752 // Scan for unvisited nodes | |
753 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
754 // For all uses, schedule late | |
755 Node* n = self->fast_out(i); // Use | |
756 | |
757 // Skip already visited children | |
758 if ( _visited.test(n->_idx) ) | |
759 continue; | |
760 | |
761 // do not traverse backward control edges | |
762 Node *use = n->is_Proj() ? n->in(0) : n; | |
763 uint use_rpo = _bbs[use->_idx]->_rpo; | |
764 | |
765 if ( use_rpo < src_rpo ) | |
766 continue; | |
767 | |
768 // Phi nodes always precede uses in a basic block | |
769 if ( use_rpo == src_rpo && use->is_Phi() ) | |
770 continue; | |
771 | |
772 unvisited = n; // Found unvisited | |
773 | |
774 // Check for possible-anti-dependent | |
775 if( !n->needs_anti_dependence_check() ) | |
776 break; // Not visited, not anti-dep; schedule it NOW | |
777 } | |
778 | |
779 // Did I find an unvisited not-anti-dependent Node? | |
780 if ( !unvisited ) | |
781 break; // All done with children; post-visit 'self' | |
782 | |
783 // Visit the unvisited Node. Contains the obvious push to | |
784 // indicate I'm entering a deeper level of recursion. I push the | |
785 // old state onto the _stack and set a new state and loop (recurse). | |
786 _stack.push(self); | |
787 self = unvisited; | |
788 } // End recursion loop | |
789 | |
790 return self; | |
791 } | |
792 | |
793 //------------------------------ComputeLatenciesBackwards---------------------- | |
794 // Compute the latency of all the instructions. | |
795 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) { | |
796 #ifndef PRODUCT | |
797 if (trace_opto_pipelining()) | |
798 tty->print("\n#---- ComputeLatenciesBackwards ----\n"); | |
799 #endif | |
800 | |
801 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
802 Node *n; | |
803 | |
804 // Walk over all the nodes from last to first | |
805 while (n = iter.next()) { | |
806 // Set the latency for the definitions of this instruction | |
807 partial_latency_of_defs(n); | |
808 } | |
809 } // end ComputeLatenciesBackwards | |
810 | |
811 //------------------------------partial_latency_of_defs------------------------ | |
812 // Compute the latency impact of this node on all defs. This computes | |
813 // a number that increases as we approach the beginning of the routine. | |
814 void PhaseCFG::partial_latency_of_defs(Node *n) { | |
815 // Set the latency for this instruction | |
816 #ifndef PRODUCT | |
817 if (trace_opto_pipelining()) { | |
818 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", | |
819 n->_idx, _node_latency.at_grow(n->_idx)); | |
820 dump(); | |
821 } | |
822 #endif | |
823 | |
824 if (n->is_Proj()) | |
825 n = n->in(0); | |
826 | |
827 if (n->is_Root()) | |
828 return; | |
829 | |
830 uint nlen = n->len(); | |
831 uint use_latency = _node_latency.at_grow(n->_idx); | |
832 uint use_pre_order = _bbs[n->_idx]->_pre_order; | |
833 | |
834 for ( uint j=0; j<nlen; j++ ) { | |
835 Node *def = n->in(j); | |
836 | |
837 if (!def || def == n) | |
838 continue; | |
839 | |
840 // Walk backwards thru projections | |
841 if (def->is_Proj()) | |
842 def = def->in(0); | |
843 | |
844 #ifndef PRODUCT | |
845 if (trace_opto_pipelining()) { | |
846 tty->print("# in(%2d): ", j); | |
847 def->dump(); | |
848 } | |
849 #endif | |
850 | |
851 // If the defining block is not known, assume it is ok | |
852 Block *def_block = _bbs[def->_idx]; | |
853 uint def_pre_order = def_block ? def_block->_pre_order : 0; | |
854 | |
855 if ( (use_pre_order < def_pre_order) || | |
856 (use_pre_order == def_pre_order && n->is_Phi()) ) | |
857 continue; | |
858 | |
859 uint delta_latency = n->latency(j); | |
860 uint current_latency = delta_latency + use_latency; | |
861 | |
862 if (_node_latency.at_grow(def->_idx) < current_latency) { | |
863 _node_latency.at_put_grow(def->_idx, current_latency); | |
864 } | |
865 | |
866 #ifndef PRODUCT | |
867 if (trace_opto_pipelining()) { | |
868 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", | |
869 use_latency, j, delta_latency, current_latency, def->_idx, | |
870 _node_latency.at_grow(def->_idx)); | |
871 } | |
872 #endif | |
873 } | |
874 } | |
875 | |
876 //------------------------------latency_from_use------------------------------- | |
877 // Compute the latency of a specific use | |
878 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) { | |
879 // If self-reference, return no latency | |
880 if (use == n || use->is_Root()) | |
881 return 0; | |
882 | |
883 uint def_pre_order = _bbs[def->_idx]->_pre_order; | |
884 uint latency = 0; | |
885 | |
886 // If the use is not a projection, then it is simple... | |
887 if (!use->is_Proj()) { | |
888 #ifndef PRODUCT | |
889 if (trace_opto_pipelining()) { | |
890 tty->print("# out(): "); | |
891 use->dump(); | |
892 } | |
893 #endif | |
894 | |
895 uint use_pre_order = _bbs[use->_idx]->_pre_order; | |
896 | |
897 if (use_pre_order < def_pre_order) | |
898 return 0; | |
899 | |
900 if (use_pre_order == def_pre_order && use->is_Phi()) | |
901 return 0; | |
902 | |
903 uint nlen = use->len(); | |
904 uint nl = _node_latency.at_grow(use->_idx); | |
905 | |
906 for ( uint j=0; j<nlen; j++ ) { | |
907 if (use->in(j) == n) { | |
908 // Change this if we want local latencies | |
909 uint ul = use->latency(j); | |
910 uint l = ul + nl; | |
911 if (latency < l) latency = l; | |
912 #ifndef PRODUCT | |
913 if (trace_opto_pipelining()) { | |
914 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d", | |
915 nl, j, ul, l, latency); | |
916 } | |
917 #endif | |
918 } | |
919 } | |
920 } else { | |
921 // This is a projection, just grab the latency of the use(s) | |
922 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) { | |
923 uint l = latency_from_use(use, def, use->fast_out(j)); | |
924 if (latency < l) latency = l; | |
925 } | |
926 } | |
927 | |
928 return latency; | |
929 } | |
930 | |
931 //------------------------------latency_from_uses------------------------------ | |
932 // Compute the latency of this instruction relative to all of it's uses. | |
933 // This computes a number that increases as we approach the beginning of the | |
934 // routine. | |
935 void PhaseCFG::latency_from_uses(Node *n) { | |
936 // Set the latency for this instruction | |
937 #ifndef PRODUCT | |
938 if (trace_opto_pipelining()) { | |
939 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", | |
940 n->_idx, _node_latency.at_grow(n->_idx)); | |
941 dump(); | |
942 } | |
943 #endif | |
944 uint latency=0; | |
945 const Node *def = n->is_Proj() ? n->in(0): n; | |
946 | |
947 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
948 uint l = latency_from_use(n, def, n->fast_out(i)); | |
949 | |
950 if (latency < l) latency = l; | |
951 } | |
952 | |
953 _node_latency.at_put_grow(n->_idx, latency); | |
954 } | |
955 | |
956 //------------------------------hoist_to_cheaper_block------------------------- | |
957 // Pick a block for node self, between early and LCA, that is a cheaper | |
958 // alternative to LCA. | |
959 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) { | |
960 const double delta = 1+PROB_UNLIKELY_MAG(4); | |
961 Block* least = LCA; | |
962 double least_freq = least->_freq; | |
963 uint target = _node_latency.at_grow(self->_idx); | |
964 uint start_latency = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
965 uint end_latency = _node_latency.at_grow(LCA->_nodes[LCA->end_idx()]->_idx); | |
966 bool in_latency = (target <= start_latency); | |
967 const Block* root_block = _bbs[_root->_idx]; | |
968 | |
969 // Turn off latency scheduling if scheduling is just plain off | |
970 if (!C->do_scheduling()) | |
971 in_latency = true; | |
972 | |
973 // Do not hoist (to cover latency) instructions which target a | |
974 // single register. Hoisting stretches the live range of the | |
975 // single register and may force spilling. | |
976 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
977 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty()) | |
978 in_latency = true; | |
979 | |
980 #ifndef PRODUCT | |
981 if (trace_opto_pipelining()) { | |
982 tty->print("# Find cheaper block for latency %d: ", | |
983 _node_latency.at_grow(self->_idx)); | |
984 self->dump(); | |
985 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
986 LCA->_pre_order, | |
987 LCA->_nodes[0]->_idx, | |
988 start_latency, | |
989 LCA->_nodes[LCA->end_idx()]->_idx, | |
990 end_latency, | |
991 least_freq); | |
992 } | |
993 #endif | |
994 | |
995 // Walk up the dominator tree from LCA (Lowest common ancestor) to | |
996 // the earliest legal location. Capture the least execution frequency. | |
997 while (LCA != early) { | |
998 LCA = LCA->_idom; // Follow up the dominator tree | |
999 | |
1000 if (LCA == NULL) { | |
1001 // Bailout without retry | |
1002 C->record_method_not_compilable("late schedule failed: LCA == NULL"); | |
1003 return least; | |
1004 } | |
1005 | |
1006 // Don't hoist machine instructions to the root basic block | |
1007 if (mach && LCA == root_block) | |
1008 break; | |
1009 | |
1010 uint start_lat = _node_latency.at_grow(LCA->_nodes[0]->_idx); | |
1011 uint end_idx = LCA->end_idx(); | |
1012 uint end_lat = _node_latency.at_grow(LCA->_nodes[end_idx]->_idx); | |
1013 double LCA_freq = LCA->_freq; | |
1014 #ifndef PRODUCT | |
1015 if (trace_opto_pipelining()) { | |
1016 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", | |
1017 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq); | |
1018 } | |
1019 #endif | |
1020 if (LCA_freq < least_freq || // Better Frequency | |
1021 ( !in_latency && // No block containing latency | |
1022 LCA_freq < least_freq * delta && // No worse frequency | |
1023 target >= end_lat && // within latency range | |
1024 !self->is_iteratively_computed() ) // But don't hoist IV increments | |
1025 // because they may end up above other uses of their phi forcing | |
1026 // their result register to be different from their input. | |
1027 ) { | |
1028 least = LCA; // Found cheaper block | |
1029 least_freq = LCA_freq; | |
1030 start_latency = start_lat; | |
1031 end_latency = end_lat; | |
1032 if (target <= start_lat) | |
1033 in_latency = true; | |
1034 } | |
1035 } | |
1036 | |
1037 #ifndef PRODUCT | |
1038 if (trace_opto_pipelining()) { | |
1039 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g", | |
1040 least->_pre_order, start_latency, least_freq); | |
1041 } | |
1042 #endif | |
1043 | |
1044 // See if the latency needs to be updated | |
1045 if (target < end_latency) { | |
1046 #ifndef PRODUCT | |
1047 if (trace_opto_pipelining()) { | |
1048 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency); | |
1049 } | |
1050 #endif | |
1051 _node_latency.at_put_grow(self->_idx, end_latency); | |
1052 partial_latency_of_defs(self); | |
1053 } | |
1054 | |
1055 return least; | |
1056 } | |
1057 | |
1058 | |
1059 //------------------------------schedule_late----------------------------------- | |
1060 // Now schedule all codes as LATE as possible. This is the LCA in the | |
1061 // dominator tree of all USES of a value. Pick the block with the least | |
1062 // loop nesting depth that is lowest in the dominator tree. | |
1063 extern const char must_clone[]; | |
1064 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) { | |
1065 #ifndef PRODUCT | |
1066 if (trace_opto_pipelining()) | |
1067 tty->print("\n#---- schedule_late ----\n"); | |
1068 #endif | |
1069 | |
1070 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); | |
1071 Node *self; | |
1072 | |
1073 // Walk over all the nodes from last to first | |
1074 while (self = iter.next()) { | |
1075 Block* early = _bbs[self->_idx]; // Earliest legal placement | |
1076 | |
1077 if (self->is_top()) { | |
1078 // Top node goes in bb #2 with other constants. | |
1079 // It must be special-cased, because it has no out edges. | |
1080 early->add_inst(self); | |
1081 continue; | |
1082 } | |
1083 | |
1084 // No uses, just terminate | |
1085 if (self->outcnt() == 0) { | |
1086 assert(self->Opcode() == Op_MachProj, "sanity"); | |
1087 continue; // Must be a dead machine projection | |
1088 } | |
1089 | |
1090 // If node is pinned in the block, then no scheduling can be done. | |
1091 if( self->pinned() ) // Pinned in block? | |
1092 continue; | |
1093 | |
1094 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; | |
1095 if (mach) { | |
1096 switch (mach->ideal_Opcode()) { | |
1097 case Op_CreateEx: | |
1098 // Don't move exception creation | |
1099 early->add_inst(self); | |
1100 continue; | |
1101 break; | |
1102 case Op_CheckCastPP: | |
1103 // Don't move CheckCastPP nodes away from their input, if the input | |
1104 // is a rawptr (5071820). | |
1105 Node *def = self->in(1); | |
1106 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) { | |
1107 early->add_inst(self); | |
1108 continue; | |
1109 } | |
1110 break; | |
1111 } | |
1112 } | |
1113 | |
1114 // Gather LCA of all uses | |
1115 Block *LCA = NULL; | |
1116 { | |
1117 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { | |
1118 // For all uses, find LCA | |
1119 Node* use = self->fast_out(i); | |
1120 LCA = raise_LCA_above_use(LCA, use, self, _bbs); | |
1121 } | |
1122 } // (Hide defs of imax, i from rest of block.) | |
1123 | |
1124 // Place temps in the block of their use. This isn't a | |
1125 // requirement for correctness but it reduces useless | |
1126 // interference between temps and other nodes. | |
1127 if (mach != NULL && mach->is_MachTemp()) { | |
1128 _bbs.map(self->_idx, LCA); | |
1129 LCA->add_inst(self); | |
1130 continue; | |
1131 } | |
1132 | |
1133 // Check if 'self' could be anti-dependent on memory | |
1134 if (self->needs_anti_dependence_check()) { | |
1135 // Hoist LCA above possible-defs and insert anti-dependences to | |
1136 // defs in new LCA block. | |
1137 LCA = insert_anti_dependences(LCA, self); | |
1138 } | |
1139 | |
1140 if (early->_dom_depth > LCA->_dom_depth) { | |
1141 // Somehow the LCA has moved above the earliest legal point. | |
1142 // (One way this can happen is via memory_early_block.) | |
1143 if (C->subsume_loads() == true && !C->failing()) { | |
1144 // Retry with subsume_loads == false | |
1145 // If this is the first failure, the sentinel string will "stick" | |
1146 // to the Compile object, and the C2Compiler will see it and retry. | |
1147 C->record_failure(C2Compiler::retry_no_subsuming_loads()); | |
1148 } else { | |
1149 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth) | |
1150 C->record_method_not_compilable("late schedule failed: incorrect graph"); | |
1151 } | |
1152 return; | |
1153 } | |
1154 | |
1155 // If there is no opportunity to hoist, then we're done. | |
1156 bool try_to_hoist = (LCA != early); | |
1157 | |
1158 // Must clone guys stay next to use; no hoisting allowed. | |
1159 // Also cannot hoist guys that alter memory or are otherwise not | |
1160 // allocatable (hoisting can make a value live longer, leading to | |
1161 // anti and output dependency problems which are normally resolved | |
1162 // by the register allocator giving everyone a different register). | |
1163 if (mach != NULL && must_clone[mach->ideal_Opcode()]) | |
1164 try_to_hoist = false; | |
1165 | |
1166 Block* late = NULL; | |
1167 if (try_to_hoist) { | |
1168 // Now find the block with the least execution frequency. | |
1169 // Start at the latest schedule and work up to the earliest schedule | |
1170 // in the dominator tree. Thus the Node will dominate all its uses. | |
1171 late = hoist_to_cheaper_block(LCA, early, self); | |
1172 } else { | |
1173 // Just use the LCA of the uses. | |
1174 late = LCA; | |
1175 } | |
1176 | |
1177 // Put the node into target block | |
1178 schedule_node_into_block(self, late); | |
1179 | |
1180 #ifdef ASSERT | |
1181 if (self->needs_anti_dependence_check()) { | |
1182 // since precedence edges are only inserted when we're sure they | |
1183 // are needed make sure that after placement in a block we don't | |
1184 // need any new precedence edges. | |
1185 verify_anti_dependences(late, self); | |
1186 } | |
1187 #endif | |
1188 } // Loop until all nodes have been visited | |
1189 | |
1190 } // end ScheduleLate | |
1191 | |
1192 //------------------------------GlobalCodeMotion------------------------------- | |
1193 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) { | |
1194 ResourceMark rm; | |
1195 | |
1196 #ifndef PRODUCT | |
1197 if (trace_opto_pipelining()) { | |
1198 tty->print("\n---- Start GlobalCodeMotion ----\n"); | |
1199 } | |
1200 #endif | |
1201 | |
1202 // Initialize the bbs.map for things on the proj_list | |
1203 uint i; | |
1204 for( i=0; i < proj_list.size(); i++ ) | |
1205 _bbs.map(proj_list[i]->_idx, NULL); | |
1206 | |
1207 // Set the basic block for Nodes pinned into blocks | |
1208 Arena *a = Thread::current()->resource_area(); | |
1209 VectorSet visited(a); | |
1210 schedule_pinned_nodes( visited ); | |
1211 | |
1212 // Find the earliest Block any instruction can be placed in. Some | |
1213 // instructions are pinned into Blocks. Unpinned instructions can | |
1214 // appear in last block in which all their inputs occur. | |
1215 visited.Clear(); | |
1216 Node_List stack(a); | |
1217 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list | |
1218 if (!schedule_early(visited, stack)) { | |
1219 // Bailout without retry | |
1220 C->record_method_not_compilable("early schedule failed"); | |
1221 return; | |
1222 } | |
1223 | |
1224 // Build Def-Use edges. | |
1225 proj_list.push(_root); // Add real root as another root | |
1226 proj_list.pop(); | |
1227 | |
1228 // Compute the latency information (via backwards walk) for all the | |
1229 // instructions in the graph | |
1230 GrowableArray<uint> node_latency; | |
1231 _node_latency = node_latency; | |
1232 | |
1233 if( C->do_scheduling() ) | |
1234 ComputeLatenciesBackwards(visited, stack); | |
1235 | |
1236 // Now schedule all codes as LATE as possible. This is the LCA in the | |
1237 // dominator tree of all USES of a value. Pick the block with the least | |
1238 // loop nesting depth that is lowest in the dominator tree. | |
1239 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() ) | |
1240 schedule_late(visited, stack); | |
1241 if( C->failing() ) { | |
1242 // schedule_late fails only when graph is incorrect. | |
1243 assert(!VerifyGraphEdges, "verification should have failed"); | |
1244 return; | |
1245 } | |
1246 | |
1247 unique = C->unique(); | |
1248 | |
1249 #ifndef PRODUCT | |
1250 if (trace_opto_pipelining()) { | |
1251 tty->print("\n---- Detect implicit null checks ----\n"); | |
1252 } | |
1253 #endif | |
1254 | |
1255 // Detect implicit-null-check opportunities. Basically, find NULL checks | |
1256 // with suitable memory ops nearby. Use the memory op to do the NULL check. | |
1257 // I can generate a memory op if there is not one nearby. | |
1258 if (C->is_method_compilation()) { | |
1259 // Don't do it for natives, adapters, or runtime stubs | |
1260 int allowed_reasons = 0; | |
1261 // ...and don't do it when there have been too many traps, globally. | |
1262 for (int reason = (int)Deoptimization::Reason_none+1; | |
1263 reason < Compile::trapHistLength; reason++) { | |
1264 assert(reason < BitsPerInt, "recode bit map"); | |
1265 if (!C->too_many_traps((Deoptimization::DeoptReason) reason)) | |
1266 allowed_reasons |= nth_bit(reason); | |
1267 } | |
1268 // By reversing the loop direction we get a very minor gain on mpegaudio. | |
1269 // Feel free to revert to a forward loop for clarity. | |
1270 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) { | |
1271 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) { | |
1272 Node *proj = matcher._null_check_tests[i ]; | |
1273 Node *val = matcher._null_check_tests[i+1]; | |
1274 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons); | |
1275 // The implicit_null_check will only perform the transformation | |
1276 // if the null branch is truly uncommon, *and* it leads to an | |
1277 // uncommon trap. Combined with the too_many_traps guards | |
1278 // above, this prevents SEGV storms reported in 6366351, | |
1279 // by recompiling offending methods without this optimization. | |
1280 } | |
1281 } | |
1282 | |
1283 #ifndef PRODUCT | |
1284 if (trace_opto_pipelining()) { | |
1285 tty->print("\n---- Start Local Scheduling ----\n"); | |
1286 } | |
1287 #endif | |
1288 | |
1289 // Schedule locally. Right now a simple topological sort. | |
1290 // Later, do a real latency aware scheduler. | |
1291 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique()); | |
1292 memset( ready_cnt, -1, C->unique() * sizeof(int) ); | |
1293 visited.Clear(); | |
1294 for (i = 0; i < _num_blocks; i++) { | |
1295 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) { | |
1296 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { | |
1297 C->record_method_not_compilable("local schedule failed"); | |
1298 } | |
1299 return; | |
1300 } | |
1301 } | |
1302 | |
1303 // If we inserted any instructions between a Call and his CatchNode, | |
1304 // clone the instructions on all paths below the Catch. | |
1305 for( i=0; i < _num_blocks; i++ ) | |
1306 _blocks[i]->call_catch_cleanup(_bbs); | |
1307 | |
1308 #ifndef PRODUCT | |
1309 if (trace_opto_pipelining()) { | |
1310 tty->print("\n---- After GlobalCodeMotion ----\n"); | |
1311 for (uint i = 0; i < _num_blocks; i++) { | |
1312 _blocks[i]->dump(); | |
1313 } | |
1314 } | |
1315 #endif | |
1316 } | |
1317 | |
1318 | |
1319 //------------------------------Estimate_Block_Frequency----------------------- | |
1320 // Estimate block frequencies based on IfNode probabilities. | |
1321 void PhaseCFG::Estimate_Block_Frequency() { | |
1322 int cnts = C->method() ? C->method()->interpreter_invocation_count() : 1; | |
1323 // Most of our algorithms will die horribly if frequency can become | |
1324 // negative so make sure cnts is a sane value. | |
1325 if( cnts <= 0 ) cnts = 1; | |
1326 float f = (float)cnts/(float)FreqCountInvocations; | |
1327 | |
1328 // Create the loop tree and calculate loop depth. | |
1329 _root_loop = create_loop_tree(); | |
1330 _root_loop->compute_loop_depth(0); | |
1331 | |
1332 // Compute block frequency of each block, relative to a single loop entry. | |
1333 _root_loop->compute_freq(); | |
1334 | |
1335 // Adjust all frequencies to be relative to a single method entry | |
1336 _root_loop->_freq = f * 1.0; | |
1337 _root_loop->scale_freq(); | |
1338 | |
1339 // force paths ending at uncommon traps to be infrequent | |
1340 Block_List worklist; | |
1341 Block* root_blk = _blocks[0]; | |
1342 for (uint i = 0; i < root_blk->num_preds(); i++) { | |
1343 Block *pb = _bbs[root_blk->pred(i)->_idx]; | |
1344 if (pb->has_uncommon_code()) { | |
1345 worklist.push(pb); | |
1346 } | |
1347 } | |
1348 while (worklist.size() > 0) { | |
1349 Block* uct = worklist.pop(); | |
1350 uct->_freq = PROB_MIN; | |
1351 for (uint i = 0; i < uct->num_preds(); i++) { | |
1352 Block *pb = _bbs[uct->pred(i)->_idx]; | |
1353 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { | |
1354 worklist.push(pb); | |
1355 } | |
1356 } | |
1357 } | |
1358 | |
1359 #ifndef PRODUCT | |
1360 if (PrintCFGBlockFreq) { | |
1361 tty->print_cr("CFG Block Frequencies"); | |
1362 _root_loop->dump_tree(); | |
1363 if (Verbose) { | |
1364 tty->print_cr("PhaseCFG dump"); | |
1365 dump(); | |
1366 tty->print_cr("Node dump"); | |
1367 _root->dump(99999); | |
1368 } | |
1369 } | |
1370 #endif | |
1371 } | |
1372 | |
1373 //----------------------------create_loop_tree-------------------------------- | |
1374 // Create a loop tree from the CFG | |
1375 CFGLoop* PhaseCFG::create_loop_tree() { | |
1376 | |
1377 #ifdef ASSERT | |
1378 assert( _blocks[0] == _broot, "" ); | |
1379 for (uint i = 0; i < _num_blocks; i++ ) { | |
1380 Block *b = _blocks[i]; | |
1381 // Check that _loop field are clear...we could clear them if not. | |
1382 assert(b->_loop == NULL, "clear _loop expected"); | |
1383 // Sanity check that the RPO numbering is reflected in the _blocks array. | |
1384 // It doesn't have to be for the loop tree to be built, but if it is not, | |
1385 // then the blocks have been reordered since dom graph building...which | |
1386 // may question the RPO numbering | |
1387 assert(b->_rpo == i, "unexpected reverse post order number"); | |
1388 } | |
1389 #endif | |
1390 | |
1391 int idct = 0; | |
1392 CFGLoop* root_loop = new CFGLoop(idct++); | |
1393 | |
1394 Block_List worklist; | |
1395 | |
1396 // Assign blocks to loops | |
1397 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block | |
1398 Block *b = _blocks[i]; | |
1399 | |
1400 if (b->head()->is_Loop()) { | |
1401 Block* loop_head = b; | |
1402 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
1403 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); | |
1404 Block* tail = _bbs[tail_n->_idx]; | |
1405 | |
1406 // Defensively filter out Loop nodes for non-single-entry loops. | |
1407 // For all reasonable loops, the head occurs before the tail in RPO. | |
1408 if (i <= tail->_rpo) { | |
1409 | |
1410 // The tail and (recursive) predecessors of the tail | |
1411 // are made members of a new loop. | |
1412 | |
1413 assert(worklist.size() == 0, "nonempty worklist"); | |
1414 CFGLoop* nloop = new CFGLoop(idct++); | |
1415 assert(loop_head->_loop == NULL, "just checking"); | |
1416 loop_head->_loop = nloop; | |
1417 // Add to nloop so push_pred() will skip over inner loops | |
1418 nloop->add_member(loop_head); | |
1419 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs); | |
1420 | |
1421 while (worklist.size() > 0) { | |
1422 Block* member = worklist.pop(); | |
1423 if (member != loop_head) { | |
1424 for (uint j = 1; j < member->num_preds(); j++) { | |
1425 nloop->push_pred(member, j, worklist, _bbs); | |
1426 } | |
1427 } | |
1428 } | |
1429 } | |
1430 } | |
1431 } | |
1432 | |
1433 // Create a member list for each loop consisting | |
1434 // of both blocks and (immediate child) loops. | |
1435 for (uint i = 0; i < _num_blocks; i++) { | |
1436 Block *b = _blocks[i]; | |
1437 CFGLoop* lp = b->_loop; | |
1438 if (lp == NULL) { | |
1439 // Not assigned to a loop. Add it to the method's pseudo loop. | |
1440 b->_loop = root_loop; | |
1441 lp = root_loop; | |
1442 } | |
1443 if (lp == root_loop || b != lp->head()) { // loop heads are already members | |
1444 lp->add_member(b); | |
1445 } | |
1446 if (lp != root_loop) { | |
1447 if (lp->parent() == NULL) { | |
1448 // Not a nested loop. Make it a child of the method's pseudo loop. | |
1449 root_loop->add_nested_loop(lp); | |
1450 } | |
1451 if (b == lp->head()) { | |
1452 // Add nested loop to member list of parent loop. | |
1453 lp->parent()->add_member(lp); | |
1454 } | |
1455 } | |
1456 } | |
1457 | |
1458 return root_loop; | |
1459 } | |
1460 | |
1461 //------------------------------push_pred-------------------------------------- | |
1462 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) { | |
1463 Node* pred_n = blk->pred(i); | |
1464 Block* pred = node_to_blk[pred_n->_idx]; | |
1465 CFGLoop *pred_loop = pred->_loop; | |
1466 if (pred_loop == NULL) { | |
1467 // Filter out blocks for non-single-entry loops. | |
1468 // For all reasonable loops, the head occurs before the tail in RPO. | |
1469 if (pred->_rpo > head()->_rpo) { | |
1470 pred->_loop = this; | |
1471 worklist.push(pred); | |
1472 } | |
1473 } else if (pred_loop != this) { | |
1474 // Nested loop. | |
1475 while (pred_loop->_parent != NULL && pred_loop->_parent != this) { | |
1476 pred_loop = pred_loop->_parent; | |
1477 } | |
1478 // Make pred's loop be a child | |
1479 if (pred_loop->_parent == NULL) { | |
1480 add_nested_loop(pred_loop); | |
1481 // Continue with loop entry predecessor. | |
1482 Block* pred_head = pred_loop->head(); | |
1483 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); | |
1484 assert(pred_head != head(), "loop head in only one loop"); | |
1485 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk); | |
1486 } else { | |
1487 assert(pred_loop->_parent == this && _parent == NULL, "just checking"); | |
1488 } | |
1489 } | |
1490 } | |
1491 | |
1492 //------------------------------add_nested_loop-------------------------------- | |
1493 // Make cl a child of the current loop in the loop tree. | |
1494 void CFGLoop::add_nested_loop(CFGLoop* cl) { | |
1495 assert(_parent == NULL, "no parent yet"); | |
1496 assert(cl != this, "not my own parent"); | |
1497 cl->_parent = this; | |
1498 CFGLoop* ch = _child; | |
1499 if (ch == NULL) { | |
1500 _child = cl; | |
1501 } else { | |
1502 while (ch->_sibling != NULL) { ch = ch->_sibling; } | |
1503 ch->_sibling = cl; | |
1504 } | |
1505 } | |
1506 | |
1507 //------------------------------compute_loop_depth----------------------------- | |
1508 // Store the loop depth in each CFGLoop object. | |
1509 // Recursively walk the children to do the same for them. | |
1510 void CFGLoop::compute_loop_depth(int depth) { | |
1511 _depth = depth; | |
1512 CFGLoop* ch = _child; | |
1513 while (ch != NULL) { | |
1514 ch->compute_loop_depth(depth + 1); | |
1515 ch = ch->_sibling; | |
1516 } | |
1517 } | |
1518 | |
1519 //------------------------------compute_freq----------------------------------- | |
1520 // Compute the frequency of each block and loop, relative to a single entry | |
1521 // into the dominating loop head. | |
1522 void CFGLoop::compute_freq() { | |
1523 // Bottom up traversal of loop tree (visit inner loops first.) | |
1524 // Set loop head frequency to 1.0, then transitively | |
1525 // compute frequency for all successors in the loop, | |
1526 // as well as for each exit edge. Inner loops are | |
1527 // treated as single blocks with loop exit targets | |
1528 // as the successor blocks. | |
1529 | |
1530 // Nested loops first | |
1531 CFGLoop* ch = _child; | |
1532 while (ch != NULL) { | |
1533 ch->compute_freq(); | |
1534 ch = ch->_sibling; | |
1535 } | |
1536 assert (_members.length() > 0, "no empty loops"); | |
1537 Block* hd = head(); | |
1538 hd->_freq = 1.0f; | |
1539 for (int i = 0; i < _members.length(); i++) { | |
1540 CFGElement* s = _members.at(i); | |
1541 float freq = s->_freq; | |
1542 if (s->is_block()) { | |
1543 Block* b = s->as_Block(); | |
1544 for (uint j = 0; j < b->_num_succs; j++) { | |
1545 Block* sb = b->_succs[j]; | |
1546 update_succ_freq(sb, freq * b->succ_prob(j)); | |
1547 } | |
1548 } else { | |
1549 CFGLoop* lp = s->as_CFGLoop(); | |
1550 assert(lp->_parent == this, "immediate child"); | |
1551 for (int k = 0; k < lp->_exits.length(); k++) { | |
1552 Block* eb = lp->_exits.at(k).get_target(); | |
1553 float prob = lp->_exits.at(k).get_prob(); | |
1554 update_succ_freq(eb, freq * prob); | |
1555 } | |
1556 } | |
1557 } | |
1558 | |
1559 #if 0 | |
1560 // Raise frequency of the loop backedge block, in an effort | |
1561 // to keep it empty. Skip the method level "loop". | |
1562 if (_parent != NULL) { | |
1563 CFGElement* s = _members.at(_members.length() - 1); | |
1564 if (s->is_block()) { | |
1565 Block* bk = s->as_Block(); | |
1566 if (bk->_num_succs == 1 && bk->_succs[0] == hd) { | |
1567 // almost any value >= 1.0f works | |
1568 // FIXME: raw constant | |
1569 bk->_freq = 1.05f; | |
1570 } | |
1571 } | |
1572 } | |
1573 #endif | |
1574 | |
1575 // For all loops other than the outer, "method" loop, | |
1576 // sum and normalize the exit probability. The "method" loop | |
1577 // should keep the initial exit probability of 1, so that | |
1578 // inner blocks do not get erroneously scaled. | |
1579 if (_depth != 0) { | |
1580 // Total the exit probabilities for this loop. | |
1581 float exits_sum = 0.0f; | |
1582 for (int i = 0; i < _exits.length(); i++) { | |
1583 exits_sum += _exits.at(i).get_prob(); | |
1584 } | |
1585 | |
1586 // Normalize the exit probabilities. Until now, the | |
1587 // probabilities estimate the possibility of exit per | |
1588 // a single loop iteration; afterward, they estimate | |
1589 // the probability of exit per loop entry. | |
1590 for (int i = 0; i < _exits.length(); i++) { | |
1591 Block* et = _exits.at(i).get_target(); | |
1592 float new_prob = _exits.at(i).get_prob() / exits_sum; | |
1593 BlockProbPair bpp(et, new_prob); | |
1594 _exits.at_put(i, bpp); | |
1595 } | |
1596 | |
1597 // Save the total, but guard against unreasoable probability, | |
1598 // as the value is used to estimate the loop trip count. | |
1599 // An infinite trip count would blur relative block | |
1600 // frequencies. | |
1601 if (exits_sum > 1.0f) exits_sum = 1.0; | |
1602 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN; | |
1603 _exit_prob = exits_sum; | |
1604 } | |
1605 } | |
1606 | |
1607 //------------------------------succ_prob------------------------------------- | |
1608 // Determine the probability of reaching successor 'i' from the receiver block. | |
1609 float Block::succ_prob(uint i) { | |
1610 int eidx = end_idx(); | |
1611 Node *n = _nodes[eidx]; // Get ending Node | |
308 | 1612 |
1613 int op = n->Opcode(); | |
1614 if (n->is_Mach()) { | |
1615 if (n->is_MachNullCheck()) { | |
1616 // Can only reach here if called after lcm. The original Op_If is gone, | |
1617 // so we attempt to infer the probability from one or both of the | |
1618 // successor blocks. | |
1619 assert(_num_succs == 2, "expecting 2 successors of a null check"); | |
1620 // If either successor has only one predecessor, then the | |
1621 // probabiltity estimate can be derived using the | |
1622 // relative frequency of the successor and this block. | |
1623 if (_succs[i]->num_preds() == 2) { | |
1624 return _succs[i]->_freq / _freq; | |
1625 } else if (_succs[1-i]->num_preds() == 2) { | |
1626 return 1 - (_succs[1-i]->_freq / _freq); | |
1627 } else { | |
1628 // Estimate using both successor frequencies | |
1629 float freq = _succs[i]->_freq; | |
1630 return freq / (freq + _succs[1-i]->_freq); | |
1631 } | |
1632 } | |
1633 op = n->as_Mach()->ideal_Opcode(); | |
1634 } | |
1635 | |
0 | 1636 |
1637 // Switch on branch type | |
1638 switch( op ) { | |
1639 case Op_CountedLoopEnd: | |
1640 case Op_If: { | |
1641 assert (i < 2, "just checking"); | |
1642 // Conditionals pass on only part of their frequency | |
1643 float prob = n->as_MachIf()->_prob; | |
1644 assert(prob >= 0.0 && prob <= 1.0, "out of range probability"); | |
1645 // If succ[i] is the FALSE branch, invert path info | |
1646 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) { | |
1647 return 1.0f - prob; // not taken | |
1648 } else { | |
1649 return prob; // taken | |
1650 } | |
1651 } | |
1652 | |
1653 case Op_Jump: | |
1654 // Divide the frequency between all successors evenly | |
1655 return 1.0f/_num_succs; | |
1656 | |
1657 case Op_Catch: { | |
1658 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); | |
1659 if (ci->_con == CatchProjNode::fall_through_index) { | |
1660 // Fall-thru path gets the lion's share. | |
1661 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs; | |
1662 } else { | |
1663 // Presume exceptional paths are equally unlikely | |
1664 return PROB_UNLIKELY_MAG(5); | |
1665 } | |
1666 } | |
1667 | |
1668 case Op_Root: | |
1669 case Op_Goto: | |
1670 // Pass frequency straight thru to target | |
1671 return 1.0f; | |
1672 | |
1673 case Op_NeverBranch: | |
1674 return 0.0f; | |
1675 | |
1676 case Op_TailCall: | |
1677 case Op_TailJump: | |
1678 case Op_Return: | |
1679 case Op_Halt: | |
1680 case Op_Rethrow: | |
1681 // Do not push out freq to root block | |
1682 return 0.0f; | |
1683 | |
1684 default: | |
1685 ShouldNotReachHere(); | |
1686 } | |
1687 | |
1688 return 0.0f; | |
1689 } | |
1690 | |
1691 //------------------------------update_succ_freq------------------------------- | |
1692 // Update the appropriate frequency associated with block 'b', a succesor of | |
1693 // a block in this loop. | |
1694 void CFGLoop::update_succ_freq(Block* b, float freq) { | |
1695 if (b->_loop == this) { | |
1696 if (b == head()) { | |
1697 // back branch within the loop | |
1698 // Do nothing now, the loop carried frequency will be | |
1699 // adjust later in scale_freq(). | |
1700 } else { | |
1701 // simple branch within the loop | |
1702 b->_freq += freq; | |
1703 } | |
1704 } else if (!in_loop_nest(b)) { | |
1705 // branch is exit from this loop | |
1706 BlockProbPair bpp(b, freq); | |
1707 _exits.append(bpp); | |
1708 } else { | |
1709 // branch into nested loop | |
1710 CFGLoop* ch = b->_loop; | |
1711 ch->_freq += freq; | |
1712 } | |
1713 } | |
1714 | |
1715 //------------------------------in_loop_nest----------------------------------- | |
1716 // Determine if block b is in the receiver's loop nest. | |
1717 bool CFGLoop::in_loop_nest(Block* b) { | |
1718 int depth = _depth; | |
1719 CFGLoop* b_loop = b->_loop; | |
1720 int b_depth = b_loop->_depth; | |
1721 if (depth == b_depth) { | |
1722 return true; | |
1723 } | |
1724 while (b_depth > depth) { | |
1725 b_loop = b_loop->_parent; | |
1726 b_depth = b_loop->_depth; | |
1727 } | |
1728 return b_loop == this; | |
1729 } | |
1730 | |
1731 //------------------------------scale_freq------------------------------------- | |
1732 // Scale frequency of loops and blocks by trip counts from outer loops | |
1733 // Do a top down traversal of loop tree (visit outer loops first.) | |
1734 void CFGLoop::scale_freq() { | |
1735 float loop_freq = _freq * trip_count(); | |
1736 for (int i = 0; i < _members.length(); i++) { | |
1737 CFGElement* s = _members.at(i); | |
1738 s->_freq *= loop_freq; | |
1739 } | |
1740 CFGLoop* ch = _child; | |
1741 while (ch != NULL) { | |
1742 ch->scale_freq(); | |
1743 ch = ch->_sibling; | |
1744 } | |
1745 } | |
1746 | |
1747 #ifndef PRODUCT | |
1748 //------------------------------dump_tree-------------------------------------- | |
1749 void CFGLoop::dump_tree() const { | |
1750 dump(); | |
1751 if (_child != NULL) _child->dump_tree(); | |
1752 if (_sibling != NULL) _sibling->dump_tree(); | |
1753 } | |
1754 | |
1755 //------------------------------dump------------------------------------------- | |
1756 void CFGLoop::dump() const { | |
1757 for (int i = 0; i < _depth; i++) tty->print(" "); | |
1758 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n", | |
1759 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq); | |
1760 for (int i = 0; i < _depth; i++) tty->print(" "); | |
1761 tty->print(" members:", _id); | |
1762 int k = 0; | |
1763 for (int i = 0; i < _members.length(); i++) { | |
1764 if (k++ >= 6) { | |
1765 tty->print("\n "); | |
1766 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
1767 k = 0; | |
1768 } | |
1769 CFGElement *s = _members.at(i); | |
1770 if (s->is_block()) { | |
1771 Block *b = s->as_Block(); | |
1772 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq); | |
1773 } else { | |
1774 CFGLoop* lp = s->as_CFGLoop(); | |
1775 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq); | |
1776 } | |
1777 } | |
1778 tty->print("\n"); | |
1779 for (int i = 0; i < _depth; i++) tty->print(" "); | |
1780 tty->print(" exits: "); | |
1781 k = 0; | |
1782 for (int i = 0; i < _exits.length(); i++) { | |
1783 if (k++ >= 7) { | |
1784 tty->print("\n "); | |
1785 for (int j = 0; j < _depth+1; j++) tty->print(" "); | |
1786 k = 0; | |
1787 } | |
1788 Block *blk = _exits.at(i).get_target(); | |
1789 float prob = _exits.at(i).get_prob(); | |
1790 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); | |
1791 } | |
1792 tty->print("\n"); | |
1793 } | |
1794 #endif |