Mercurial > hg > graal-jvmci-8
view src/share/vm/c1/c1_ValueMap.cpp @ 3249:e1162778c1c8
7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes
author | johnc |
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date | Thu, 07 Apr 2011 09:53:20 -0700 |
parents | f95d63e2154a |
children | f067b4e0e04b |
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/* * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "c1/c1_Canonicalizer.hpp" #include "c1/c1_IR.hpp" #include "c1/c1_ValueMap.hpp" #include "utilities/bitMap.inline.hpp" #ifndef PRODUCT int ValueMap::_number_of_finds = 0; int ValueMap::_number_of_hits = 0; int ValueMap::_number_of_kills = 0; #define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; } #else #define TRACE_VALUE_NUMBERING(code) #endif ValueMap::ValueMap() : _nesting(0) , _entries(ValueMapInitialSize, NULL) , _killed_values() , _entry_count(0) { NOT_PRODUCT(reset_statistics()); } ValueMap::ValueMap(ValueMap* old) : _nesting(old->_nesting + 1) , _entries(old->_entries.length()) , _killed_values() , _entry_count(old->_entry_count) { for (int i = size() - 1; i >= 0; i--) { _entries.at_put(i, old->entry_at(i)); } _killed_values.set_from(&old->_killed_values); } void ValueMap::increase_table_size() { int old_size = size(); int new_size = old_size * 2 + 1; ValueMapEntryList worklist(8); ValueMapEntryArray new_entries(new_size, NULL); int new_entry_count = 0; TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size)); for (int i = old_size - 1; i >= 0; i--) { ValueMapEntry* entry; for (entry = entry_at(i); entry != NULL; entry = entry->next()) { if (!is_killed(entry->value())) { worklist.push(entry); } } while (!worklist.is_empty()) { entry = worklist.pop(); int new_index = entry_index(entry->hash(), new_size); if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) { // changing entries with a lower nesting than the current nesting of the table // is not allowed because then the same entry is contained in multiple value maps. // clone entry when next-pointer must be changed entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL); } entry->set_next(new_entries.at(new_index)); new_entries.at_put(new_index, entry); new_entry_count++; } } _entries = new_entries; _entry_count = new_entry_count; } Value ValueMap::find_insert(Value x) { const intx hash = x->hash(); if (hash != 0) { // 0 hash means: exclude from value numbering NOT_PRODUCT(_number_of_finds++); for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) { if (entry->hash() == hash) { Value f = entry->value(); if (!is_killed(f) && f->is_equal(x)) { NOT_PRODUCT(_number_of_hits++); TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: %s %c%d equal to %c%d (size %d, entries %d, nesting-diff %d)", x->name(), x->type()->tchar(), x->id(), f->type()->tchar(), f->id(), size(), entry_count(), nesting() - entry->nesting())); if (entry->nesting() != nesting() && f->as_Constant() == NULL) { // non-constant values of of another block must be pinned, // otherwise it is possible that they are not evaluated f->pin(Instruction::PinGlobalValueNumbering); } return f; } } } // x not found, so insert it if (entry_count() >= size_threshold()) { increase_table_size(); } int idx = entry_index(hash, size()); _entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx))); _entry_count++; TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: insert %s %c%d (size %d, entries %d, nesting %d)", x->name(), x->type()->tchar(), x->id(), size(), entry_count(), nesting())); } return x; } #define GENERIC_KILL_VALUE(must_kill_implementation) \ NOT_PRODUCT(_number_of_kills++); \ \ for (int i = size() - 1; i >= 0; i--) { \ ValueMapEntry* prev_entry = NULL; \ for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \ Value value = entry->value(); \ \ must_kill_implementation(must_kill, entry, value) \ \ if (must_kill) { \ kill_value(value); \ \ if (prev_entry == NULL) { \ _entries.at_put(i, entry->next()); \ _entry_count--; \ } else if (prev_entry->nesting() == nesting()) { \ prev_entry->set_next(entry->next()); \ _entry_count--; \ } else { \ prev_entry = entry; \ } \ \ TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: killed %s %c%d (size %d, entries %d, nesting-diff %d)", value->name(), value->type()->tchar(), value->id(), size(), entry_count(), nesting() - entry->nesting())); \ } else { \ prev_entry = entry; \ } \ } \ } \ #define MUST_KILL_MEMORY(must_kill, entry, value) \ bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL; #define MUST_KILL_ARRAY(must_kill, entry, value) \ bool must_kill = value->as_LoadIndexed() != NULL \ && value->type()->tag() == type->tag(); #define MUST_KILL_FIELD(must_kill, entry, value) \ /* ciField's are not unique; must compare their contents */ \ LoadField* lf = value->as_LoadField(); \ bool must_kill = lf != NULL \ && lf->field()->holder() == field->holder() \ && lf->field()->offset() == field->offset(); #define MUST_KILL_EXCEPTION(must_kill, entry, value) \ assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \ bool must_kill = (entry->nesting() == nesting() - 1); void ValueMap::kill_memory() { GENERIC_KILL_VALUE(MUST_KILL_MEMORY); } void ValueMap::kill_array(ValueType* type) { GENERIC_KILL_VALUE(MUST_KILL_ARRAY); } void ValueMap::kill_field(ciField* field) { GENERIC_KILL_VALUE(MUST_KILL_FIELD); } void ValueMap::kill_exception() { GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION); } void ValueMap::kill_map(ValueMap* map) { assert(is_global_value_numbering(), "only for global value numbering"); _killed_values.set_union(&map->_killed_values); } void ValueMap::kill_all() { assert(is_local_value_numbering(), "only for local value numbering"); for (int i = size() - 1; i >= 0; i--) { _entries.at_put(i, NULL); } _entry_count = 0; } #ifndef PRODUCT void ValueMap::print() { tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting()); int entries = 0; for (int i = 0; i < size(); i++) { if (entry_at(i) != NULL) { tty->print(" %2d: ", i); for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { Value value = entry->value(); tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting()); entries++; } tty->print_cr("NULL"); } } _killed_values.print(); assert(entry_count() == entries, "entry_count incorrect"); } void ValueMap::reset_statistics() { _number_of_finds = 0; _number_of_hits = 0; _number_of_kills = 0; } void ValueMap::print_statistics() { float hit_rate = 0; if (_number_of_finds != 0) { hit_rate = (float)_number_of_hits / _number_of_finds; } tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate); } #endif class ShortLoopOptimizer : public ValueNumberingVisitor { private: GlobalValueNumbering* _gvn; BlockList _loop_blocks; bool _too_complicated_loop; // simplified access to methods of GlobalValueNumbering ValueMap* current_map() { return _gvn->current_map(); } ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); } // implementation for abstract methods of ValueNumberingVisitor void kill_memory() { _too_complicated_loop = true; } void kill_field(ciField* field) { current_map()->kill_field(field); }; void kill_array(ValueType* type) { current_map()->kill_array(type); }; public: ShortLoopOptimizer(GlobalValueNumbering* gvn) : _gvn(gvn) , _loop_blocks(ValueMapMaxLoopSize) , _too_complicated_loop(false) { } bool process(BlockBegin* loop_header); }; bool ShortLoopOptimizer::process(BlockBegin* loop_header) { TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block")); _too_complicated_loop = false; _loop_blocks.clear(); _loop_blocks.append(loop_header); for (int i = 0; i < _loop_blocks.length(); i++) { BlockBegin* block = _loop_blocks.at(i); TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id())); if (block->is_set(BlockBegin::exception_entry_flag)) { // this would be too complicated return false; } // add predecessors to worklist for (int j = block->number_of_preds() - 1; j >= 0; j--) { BlockBegin* pred = block->pred_at(j); ValueMap* pred_map = value_map_of(pred); if (pred_map != NULL) { current_map()->kill_map(pred_map); } else if (!_loop_blocks.contains(pred)) { if (_loop_blocks.length() >= ValueMapMaxLoopSize) { return false; } _loop_blocks.append(pred); } } // use the instruction visitor for killing values for (Value instr = block->next(); instr != NULL; instr = instr->next()) { instr->visit(this); if (_too_complicated_loop) { return false; } } } TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized")); return true; } GlobalValueNumbering::GlobalValueNumbering(IR* ir) : _current_map(NULL) , _value_maps(ir->linear_scan_order()->length(), NULL) { TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering")); ShortLoopOptimizer short_loop_optimizer(this); int subst_count = 0; BlockList* blocks = ir->linear_scan_order(); int num_blocks = blocks->length(); BlockBegin* start_block = blocks->at(0); assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block"); assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions"); // initial, empty value map with nesting 0 set_value_map_of(start_block, new ValueMap()); for (int i = 1; i < num_blocks; i++) { BlockBegin* block = blocks->at(i); TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id())); int num_preds = block->number_of_preds(); assert(num_preds > 0, "block must have predecessors"); BlockBegin* dominator = block->dominator(); assert(dominator != NULL, "dominator must exist"); assert(value_map_of(dominator) != NULL, "value map of dominator must exist"); // create new value map with increased nesting _current_map = new ValueMap(value_map_of(dominator)); if (num_preds == 1) { assert(dominator == block->pred_at(0), "dominator must be equal to predecessor"); // nothing to do here } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) { // block has incoming backward branches -> try to optimize short loops if (!short_loop_optimizer.process(block)) { // loop is too complicated, so kill all memory loads because there might be // stores to them in the loop current_map()->kill_memory(); } } else { // only incoming forward branches that are already processed for (int j = 0; j < num_preds; j++) { BlockBegin* pred = block->pred_at(j); ValueMap* pred_map = value_map_of(pred); if (pred_map != NULL) { // propagate killed values of the predecessor to this block current_map()->kill_map(value_map_of(pred)); } else { // kill all memory loads because predecessor not yet processed // (this can happen with non-natural loops and OSR-compiles) current_map()->kill_memory(); } } } if (block->is_set(BlockBegin::exception_entry_flag)) { current_map()->kill_exception(); } TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print()); // visit all instructions of this block for (Value instr = block->next(); instr != NULL; instr = instr->next()) { assert(!instr->has_subst(), "substitution already set"); // check if instruction kills any values instr->visit(this); if (instr->hash() != 0) { Value f = current_map()->find_insert(instr); if (f != instr) { assert(!f->has_subst(), "can't have a substitution"); instr->set_subst(f); subst_count++; } } } // remember value map for successors set_value_map_of(block, current_map()); } if (subst_count != 0) { SubstitutionResolver resolver(ir); } TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics()); }