--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/compiler/methodLiveness.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1063 @@
+/*
+ * Copyright 1998-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// The MethodLiveness class performs a simple liveness analysis on a method
+// in order to decide which locals are live (that is, will be used again) at
+// a particular bytecode index (bci).
+//
+// The algorithm goes:
+//
+// 1. Break the method into a set of basic blocks. For each basic block we
+// also keep track of its set of predecessors through normal control flow
+// and predecessors through exceptional control flow.
+//
+// 2. For each basic block, compute two sets, gen (the set of values used before
+// they are defined) and kill (the set of values defined before they are used)
+// in the basic block. A basic block "needs" the locals in its gen set to
+// perform its computation. A basic block "provides" values for the locals in
+// its kill set, allowing a need from a successor to be ignored.
+//
+// 3. Liveness information (the set of locals which are needed) is pushed backwards through
+// the program, from blocks to their predecessors. We compute and store liveness
+// information for the normal/exceptional exit paths for each basic block. When
+// this process reaches a fixed point, we are done.
+//
+// 4. When we are asked about the liveness at a particular bci with a basic block, we
+// compute gen/kill sets which represent execution from that bci to the exit of
+// its blocks. We then compose this range gen/kill information with the normal
+// and exceptional exit information for the block to produce liveness information
+// at that bci.
+//
+// The algorithm is approximate in many respects. Notably:
+//
+// 1. We do not do the analysis necessary to match jsr's with the appropriate ret.
+// Instead we make the conservative assumption that any ret can return to any
+// jsr return site.
+// 2. Instead of computing the effects of exceptions at every instruction, we
+// summarize the effects of all exceptional continuations from the block as
+// a single set (_exception_exit), losing some information but simplifying the
+// analysis.
+
+
+# include "incls/_precompiled.incl"
+# include "incls/_methodLiveness.cpp.incl"
+
+//--------------------------------------------------------------------------
+// The BitCounter class is used for counting the number of bits set in
+// some BitMap. It is only used when collecting liveness statistics.
+
+#ifndef PRODUCT
+
+class BitCounter: public BitMapClosure {
+ private:
+ int _count;
+ public:
+ BitCounter() : _count(0) {}
+
+ // Callback when bit in map is set
+ virtual void do_bit(size_t offset) {
+ _count++;
+ }
+
+ int count() {
+ return _count;
+ }
+};
+
+
+//--------------------------------------------------------------------------
+
+
+// Counts
+long MethodLiveness::_total_bytes = 0;
+int MethodLiveness::_total_methods = 0;
+
+long MethodLiveness::_total_blocks = 0;
+int MethodLiveness::_max_method_blocks = 0;
+
+long MethodLiveness::_total_edges = 0;
+int MethodLiveness::_max_block_edges = 0;
+
+long MethodLiveness::_total_exc_edges = 0;
+int MethodLiveness::_max_block_exc_edges = 0;
+
+long MethodLiveness::_total_method_locals = 0;
+int MethodLiveness::_max_method_locals = 0;
+
+long MethodLiveness::_total_locals_queried = 0;
+long MethodLiveness::_total_live_locals_queried = 0;
+
+long MethodLiveness::_total_visits = 0;
+
+#endif
+
+// Timers
+elapsedTimer MethodLiveness::_time_build_graph;
+elapsedTimer MethodLiveness::_time_gen_kill;
+elapsedTimer MethodLiveness::_time_flow;
+elapsedTimer MethodLiveness::_time_query;
+elapsedTimer MethodLiveness::_time_total;
+
+MethodLiveness::MethodLiveness(Arena* arena, ciMethod* method)
+#ifdef COMPILER1
+ : _bci_block_start((uintptr_t*)arena->Amalloc((method->code_size() >> LogBitsPerByte) + 1), method->code_size())
+#endif
+{
+ _arena = arena;
+ _method = method;
+ _bit_map_size_bits = method->max_locals();
+ _bit_map_size_words = (_bit_map_size_bits / sizeof(unsigned int)) + 1;
+
+#ifdef COMPILER1
+ _bci_block_start.clear();
+#endif
+}
+
+void MethodLiveness::compute_liveness() {
+#ifndef PRODUCT
+ if (TraceLivenessGen) {
+ tty->print_cr("################################################################");
+ tty->print("# Computing liveness information for ");
+ method()->print_short_name();
+ }
+
+ if (TimeLivenessAnalysis) _time_total.start();
+#endif
+
+ {
+ TraceTime buildGraph(NULL, &_time_build_graph, TimeLivenessAnalysis);
+ init_basic_blocks();
+ }
+ {
+ TraceTime genKill(NULL, &_time_gen_kill, TimeLivenessAnalysis);
+ init_gen_kill();
+ }
+ {
+ TraceTime flow(NULL, &_time_flow, TimeLivenessAnalysis);
+ propagate_liveness();
+ }
+
+#ifndef PRODUCT
+ if (TimeLivenessAnalysis) _time_total.stop();
+
+ if (TimeLivenessAnalysis) {
+ // Collect statistics
+ _total_bytes += method()->code_size();
+ _total_methods++;
+
+ int num_blocks = _block_count;
+ _total_blocks += num_blocks;
+ _max_method_blocks = MAX2(num_blocks,_max_method_blocks);
+
+ for (int i=0; i<num_blocks; i++) {
+ BasicBlock *block = _block_list[i];
+
+ int numEdges = block->_normal_predecessors->length();
+ int numExcEdges = block->_exception_predecessors->length();
+
+ _total_edges += numEdges;
+ _total_exc_edges += numExcEdges;
+ _max_block_edges = MAX2(numEdges,_max_block_edges);
+ _max_block_exc_edges = MAX2(numExcEdges,_max_block_exc_edges);
+ }
+
+ int numLocals = _bit_map_size_bits;
+ _total_method_locals += numLocals;
+ _max_method_locals = MAX2(numLocals,_max_method_locals);
+ }
+#endif
+}
+
+
+void MethodLiveness::init_basic_blocks() {
+ bool bailout = false;
+
+ int method_len = method()->code_size();
+ ciMethodBlocks *mblocks = method()->get_method_blocks();
+
+ // Create an array to store the bci->BasicBlock mapping.
+ _block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
+
+ _block_count = mblocks->num_blocks();
+ _block_list = (BasicBlock **) arena()->Amalloc(sizeof(BasicBlock *) * _block_count);
+
+ // Used for patching up jsr/ret control flow.
+ GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
+ GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
+
+ // generate our block list from ciMethodBlocks
+ for (int blk = 0; blk < _block_count; blk++) {
+ ciBlock *cib = mblocks->block(blk);
+ int start_bci = cib->start_bci();
+ _block_list[blk] = new (arena()) BasicBlock(this, start_bci, cib->limit_bci());
+ _block_map->at_put(start_bci, _block_list[blk]);
+#ifdef COMPILER1
+ // mark all bcis where a new basic block starts
+ _bci_block_start.set_bit(start_bci);
+#endif // COMPILER1
+ }
+ // fill in the predecessors of blocks
+ ciBytecodeStream bytes(method());
+
+ for (int blk = 0; blk < _block_count; blk++) {
+ BasicBlock *current_block = _block_list[blk];
+ int bci = mblocks->block(blk)->control_bci();
+
+ if (bci == ciBlock::fall_through_bci) {
+ int limit = current_block->limit_bci();
+ if (limit < method_len) {
+ BasicBlock *next = _block_map->at(limit);
+ assert( next != NULL, "must be a block immediately following this one.");
+ next->add_normal_predecessor(current_block);
+ }
+ continue;
+ }
+ bytes.reset_to_bci(bci);
+ Bytecodes::Code code = bytes.next();
+ BasicBlock *dest;
+
+ // Now we need to interpret the instruction's effect
+ // on control flow.
+ assert (current_block != NULL, "we must have a current block");
+ switch (code) {
+ case Bytecodes::_ifeq:
+ case Bytecodes::_ifne:
+ case Bytecodes::_iflt:
+ case Bytecodes::_ifge:
+ case Bytecodes::_ifgt:
+ case Bytecodes::_ifle:
+ case Bytecodes::_if_icmpeq:
+ case Bytecodes::_if_icmpne:
+ case Bytecodes::_if_icmplt:
+ case Bytecodes::_if_icmpge:
+ case Bytecodes::_if_icmpgt:
+ case Bytecodes::_if_icmple:
+ case Bytecodes::_if_acmpeq:
+ case Bytecodes::_if_acmpne:
+ case Bytecodes::_ifnull:
+ case Bytecodes::_ifnonnull:
+ // Two way branch. Set predecessors at each destination.
+ dest = _block_map->at(bytes.next_bci());
+ assert(dest != NULL, "must be a block immediately following this one.");
+ dest->add_normal_predecessor(current_block);
+
+ dest = _block_map->at(bytes.get_dest());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ break;
+ case Bytecodes::_goto:
+ dest = _block_map->at(bytes.get_dest());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ break;
+ case Bytecodes::_goto_w:
+ dest = _block_map->at(bytes.get_far_dest());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ break;
+ case Bytecodes::_tableswitch:
+ {
+ Bytecode_tableswitch *tableswitch =
+ Bytecode_tableswitch_at(bytes.cur_bcp());
+
+ int len = tableswitch->length();
+
+ dest = _block_map->at(bci + tableswitch->default_offset());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ while (--len >= 0) {
+ dest = _block_map->at(bci + tableswitch->dest_offset_at(len));
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ }
+ break;
+ }
+
+ case Bytecodes::_lookupswitch:
+ {
+ Bytecode_lookupswitch *lookupswitch =
+ Bytecode_lookupswitch_at(bytes.cur_bcp());
+
+ int npairs = lookupswitch->number_of_pairs();
+
+ dest = _block_map->at(bci + lookupswitch->default_offset());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ while(--npairs >= 0) {
+ LookupswitchPair *pair = lookupswitch->pair_at(npairs);
+ dest = _block_map->at( bci + pair->offset());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ }
+ break;
+ }
+
+ case Bytecodes::_jsr:
+ {
+ assert(bytes.is_wide()==false, "sanity check");
+ dest = _block_map->at(bytes.get_dest());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
+ assert(jsrExit != NULL, "jsr return bci must start a block.");
+ jsr_exit_list->append(jsrExit);
+ break;
+ }
+ case Bytecodes::_jsr_w:
+ {
+ dest = _block_map->at(bytes.get_far_dest());
+ assert(dest != NULL, "branch desination must start a block.");
+ dest->add_normal_predecessor(current_block);
+ BasicBlock *jsrExit = _block_map->at(current_block->limit_bci());
+ assert(jsrExit != NULL, "jsr return bci must start a block.");
+ jsr_exit_list->append(jsrExit);
+ break;
+ }
+
+ case Bytecodes::_wide:
+ assert(false, "wide opcodes should not be seen here");
+ break;
+ case Bytecodes::_athrow:
+ case Bytecodes::_ireturn:
+ case Bytecodes::_lreturn:
+ case Bytecodes::_freturn:
+ case Bytecodes::_dreturn:
+ case Bytecodes::_areturn:
+ case Bytecodes::_return:
+ // These opcodes are not the normal predecessors of any other opcodes.
+ break;
+ case Bytecodes::_ret:
+ // We will patch up jsr/rets in a subsequent pass.
+ ret_list->append(current_block);
+ break;
+ case Bytecodes::_breakpoint:
+ // Bail out of there are breakpoints in here.
+ bailout = true;
+ break;
+ default:
+ // Do nothing.
+ break;
+ }
+ }
+ // Patch up the jsr/ret's. We conservatively assume that any ret
+ // can return to any jsr site.
+ int ret_list_len = ret_list->length();
+ int jsr_exit_list_len = jsr_exit_list->length();
+ if (ret_list_len > 0 && jsr_exit_list_len > 0) {
+ for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
+ BasicBlock *jsrExit = jsr_exit_list->at(i);
+ for (int i = ret_list_len - 1; i >= 0; i--) {
+ jsrExit->add_normal_predecessor(ret_list->at(i));
+ }
+ }
+ }
+
+ // Compute exception edges.
+ for (int b=_block_count-1; b >= 0; b--) {
+ BasicBlock *block = _block_list[b];
+ int block_start = block->start_bci();
+ int block_limit = block->limit_bci();
+ ciExceptionHandlerStream handlers(method());
+ for (; !handlers.is_done(); handlers.next()) {
+ ciExceptionHandler* handler = handlers.handler();
+ int start = handler->start();
+ int limit = handler->limit();
+ int handler_bci = handler->handler_bci();
+
+ int intersect_start = MAX2(block_start, start);
+ int intersect_limit = MIN2(block_limit, limit);
+ if (intersect_start < intersect_limit) {
+ // The catch range has a nonempty intersection with this
+ // basic block. That means this basic block can be an
+ // exceptional predecessor.
+ _block_map->at(handler_bci)->add_exception_predecessor(block);
+
+ if (handler->is_catch_all()) {
+ // This is a catch-all block.
+ if (intersect_start == block_start && intersect_limit == block_limit) {
+ // The basic block is entirely contained in this catch-all block.
+ // Skip the rest of the exception handlers -- they can never be
+ // reached in execution.
+ break;
+ }
+ }
+ }
+ }
+ }
+}
+
+void MethodLiveness::init_gen_kill() {
+ for (int i=_block_count-1; i >= 0; i--) {
+ _block_list[i]->compute_gen_kill(method());
+ }
+}
+
+void MethodLiveness::propagate_liveness() {
+ int num_blocks = _block_count;
+ BasicBlock *block;
+
+ // We start our work list off with all blocks in it.
+ // Alternately, we could start off the work list with the list of all
+ // blocks which could exit the method directly, along with one block
+ // from any infinite loop. If this matters, it can be changed. It
+ // may not be clear from looking at the code, but the order of the
+ // workList will be the opposite of the creation order of the basic
+ // blocks, which should be decent for quick convergence (with the
+ // possible exception of exception handlers, which are all created
+ // early).
+ _work_list = NULL;
+ for (int i = 0; i < num_blocks; i++) {
+ block = _block_list[i];
+ block->set_next(_work_list);
+ block->set_on_work_list(true);
+ _work_list = block;
+ }
+
+
+ while ((block = work_list_get()) != NULL) {
+ block->propagate(this);
+ NOT_PRODUCT(_total_visits++;)
+ }
+}
+
+void MethodLiveness::work_list_add(BasicBlock *block) {
+ if (!block->on_work_list()) {
+ block->set_next(_work_list);
+ block->set_on_work_list(true);
+ _work_list = block;
+ }
+}
+
+MethodLiveness::BasicBlock *MethodLiveness::work_list_get() {
+ BasicBlock *block = _work_list;
+ if (block != NULL) {
+ block->set_on_work_list(false);
+ _work_list = block->next();
+ }
+ return block;
+}
+
+
+MethodLivenessResult MethodLiveness::get_liveness_at(int entry_bci) {
+ int bci = entry_bci;
+ bool is_entry = false;
+ if (entry_bci == InvocationEntryBci) {
+ is_entry = true;
+ bci = 0;
+ }
+
+ MethodLivenessResult answer(NULL,0);
+
+ if (_block_count > 0) {
+ if (TimeLivenessAnalysis) _time_total.start();
+ if (TimeLivenessAnalysis) _time_query.start();
+
+ assert( 0 <= bci && bci < method()->code_size(), "bci out of range" );
+ BasicBlock *block = _block_map->at(bci);
+ // We may not be at the block start, so search backwards to find the block
+ // containing bci.
+ int t = bci;
+ while (block == NULL && t > 0) {
+ block = _block_map->at(--t);
+ }
+ assert( block != NULL, "invalid bytecode index; must be instruction index" );
+ assert(bci >= block->start_bci() && bci < block->limit_bci(), "block must contain bci.");
+
+ answer = block->get_liveness_at(method(), bci);
+
+ if (is_entry && method()->is_synchronized() && !method()->is_static()) {
+ // Synchronized methods use the receiver once on entry.
+ answer.at_put(0, true);
+ }
+
+#ifndef PRODUCT
+ if (TraceLivenessQuery) {
+ tty->print("Liveness query of ");
+ method()->print_short_name();
+ tty->print(" @ %d : result is ", bci);
+ answer.print_on(tty);
+ }
+
+ if (TimeLivenessAnalysis) _time_query.stop();
+ if (TimeLivenessAnalysis) _time_total.stop();
+#endif
+ }
+
+#ifndef PRODUCT
+ if (TimeLivenessAnalysis) {
+ // Collect statistics.
+ _total_locals_queried += _bit_map_size_bits;
+ BitCounter counter;
+ answer.iterate(&counter);
+ _total_live_locals_queried += counter.count();
+ }
+#endif
+
+ return answer;
+}
+
+
+#ifndef PRODUCT
+
+void MethodLiveness::print_times() {
+ tty->print_cr ("Accumulated liveness analysis times/statistics:");
+ tty->print_cr ("-----------------------------------------------");
+ tty->print_cr (" Total : %3.3f sec.", _time_total.seconds());
+ tty->print_cr (" Build graph : %3.3f sec. (%2.2f%%)", _time_build_graph.seconds(),
+ _time_build_graph.seconds() * 100 / _time_total.seconds());
+ tty->print_cr (" Gen / Kill : %3.3f sec. (%2.2f%%)", _time_gen_kill.seconds(),
+ _time_gen_kill.seconds() * 100 / _time_total.seconds());
+ tty->print_cr (" Dataflow : %3.3f sec. (%2.2f%%)", _time_flow.seconds(),
+ _time_flow.seconds() * 100 / _time_total.seconds());
+ tty->print_cr (" Query : %3.3f sec. (%2.2f%%)", _time_query.seconds(),
+ _time_query.seconds() * 100 / _time_total.seconds());
+ tty->print_cr (" #bytes : %8d (%3.0f bytes per sec)",
+ _total_bytes,
+ _total_bytes / _time_total.seconds());
+ tty->print_cr (" #methods : %8d (%3.0f methods per sec)",
+ _total_methods,
+ _total_methods / _time_total.seconds());
+ tty->print_cr (" avg locals : %3.3f max locals : %3d",
+ (float)_total_method_locals / _total_methods,
+ _max_method_locals);
+ tty->print_cr (" avg blocks : %3.3f max blocks : %3d",
+ (float)_total_blocks / _total_methods,
+ _max_method_blocks);
+ tty->print_cr (" avg bytes : %3.3f",
+ (float)_total_bytes / _total_methods);
+ tty->print_cr (" #blocks : %8d",
+ _total_blocks);
+ tty->print_cr (" avg normal predecessors : %3.3f max normal predecessors : %3d",
+ (float)_total_edges / _total_blocks,
+ _max_block_edges);
+ tty->print_cr (" avg exception predecessors : %3.3f max exception predecessors : %3d",
+ (float)_total_exc_edges / _total_blocks,
+ _max_block_exc_edges);
+ tty->print_cr (" avg visits : %3.3f",
+ (float)_total_visits / _total_blocks);
+ tty->print_cr (" #locals queried : %8d #live : %8d %%live : %2.2f%%",
+ _total_locals_queried,
+ _total_live_locals_queried,
+ 100.0 * _total_live_locals_queried / _total_locals_queried);
+}
+
+#endif
+
+
+MethodLiveness::BasicBlock::BasicBlock(MethodLiveness *analyzer, int start, int limit) :
+ _gen((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
+ analyzer->bit_map_size_bits()),
+ _kill((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
+ analyzer->bit_map_size_bits()),
+ _entry((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
+ analyzer->bit_map_size_bits()),
+ _normal_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
+ analyzer->bit_map_size_bits()),
+ _exception_exit((uintptr_t*)analyzer->arena()->Amalloc(BytesPerWord * analyzer->bit_map_size_words()),
+ analyzer->bit_map_size_bits()),
+ _last_bci(-1) {
+ _analyzer = analyzer;
+ _start_bci = start;
+ _limit_bci = limit;
+ _normal_predecessors =
+ new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
+ _exception_predecessors =
+ new (analyzer->arena()) GrowableArray<MethodLiveness::BasicBlock*>(analyzer->arena(), 5, 0, NULL);
+ _normal_exit.clear();
+ _exception_exit.clear();
+ _entry.clear();
+
+ // this initialization is not strictly necessary.
+ // _gen and _kill are cleared at the beginning of compute_gen_kill_range()
+ _gen.clear();
+ _kill.clear();
+}
+
+
+
+MethodLiveness::BasicBlock *MethodLiveness::BasicBlock::split(int split_bci) {
+ int start = _start_bci;
+ int limit = _limit_bci;
+
+ if (TraceLivenessGen) {
+ tty->print_cr(" ** Splitting block (%d,%d) at %d", start, limit, split_bci);
+ }
+
+ GrowableArray<BasicBlock*>* save_predecessors = _normal_predecessors;
+
+ assert (start < split_bci && split_bci < limit, "improper split");
+
+ // Make a new block to cover the first half of the range.
+ BasicBlock *first_half = new (_analyzer->arena()) BasicBlock(_analyzer, start, split_bci);
+
+ // Assign correct values to the second half (this)
+ _normal_predecessors = first_half->_normal_predecessors;
+ _start_bci = split_bci;
+ add_normal_predecessor(first_half);
+
+ // Assign correct predecessors to the new first half
+ first_half->_normal_predecessors = save_predecessors;
+
+ return first_half;
+}
+
+void MethodLiveness::BasicBlock::compute_gen_kill(ciMethod* method) {
+ ciBytecodeStream bytes(method);
+ bytes.reset_to_bci(start_bci());
+ bytes.set_max_bci(limit_bci());
+ compute_gen_kill_range(&bytes);
+
+}
+
+void MethodLiveness::BasicBlock::compute_gen_kill_range(ciBytecodeStream *bytes) {
+ _gen.clear();
+ _kill.clear();
+
+ while (bytes->next() != ciBytecodeStream::EOBC()) {
+ compute_gen_kill_single(bytes);
+ }
+}
+
+void MethodLiveness::BasicBlock::compute_gen_kill_single(ciBytecodeStream *instruction) {
+ int localNum;
+
+ // We prohibit _gen and _kill from having locals in common. If we
+ // know that one is definitely going to be applied before the other,
+ // we could save some computation time by relaxing this prohibition.
+
+ switch (instruction->cur_bc()) {
+ case Bytecodes::_nop:
+ case Bytecodes::_goto:
+ case Bytecodes::_goto_w:
+ case Bytecodes::_aconst_null:
+ case Bytecodes::_new:
+ case Bytecodes::_iconst_m1:
+ case Bytecodes::_iconst_0:
+ case Bytecodes::_iconst_1:
+ case Bytecodes::_iconst_2:
+ case Bytecodes::_iconst_3:
+ case Bytecodes::_iconst_4:
+ case Bytecodes::_iconst_5:
+ case Bytecodes::_fconst_0:
+ case Bytecodes::_fconst_1:
+ case Bytecodes::_fconst_2:
+ case Bytecodes::_bipush:
+ case Bytecodes::_sipush:
+ case Bytecodes::_lconst_0:
+ case Bytecodes::_lconst_1:
+ case Bytecodes::_dconst_0:
+ case Bytecodes::_dconst_1:
+ case Bytecodes::_ldc2_w:
+ case Bytecodes::_ldc:
+ case Bytecodes::_ldc_w:
+ case Bytecodes::_iaload:
+ case Bytecodes::_faload:
+ case Bytecodes::_baload:
+ case Bytecodes::_caload:
+ case Bytecodes::_saload:
+ case Bytecodes::_laload:
+ case Bytecodes::_daload:
+ case Bytecodes::_aaload:
+ case Bytecodes::_iastore:
+ case Bytecodes::_fastore:
+ case Bytecodes::_bastore:
+ case Bytecodes::_castore:
+ case Bytecodes::_sastore:
+ case Bytecodes::_lastore:
+ case Bytecodes::_dastore:
+ case Bytecodes::_aastore:
+ case Bytecodes::_pop:
+ case Bytecodes::_pop2:
+ case Bytecodes::_dup:
+ case Bytecodes::_dup_x1:
+ case Bytecodes::_dup_x2:
+ case Bytecodes::_dup2:
+ case Bytecodes::_dup2_x1:
+ case Bytecodes::_dup2_x2:
+ case Bytecodes::_swap:
+ case Bytecodes::_iadd:
+ case Bytecodes::_fadd:
+ case Bytecodes::_isub:
+ case Bytecodes::_fsub:
+ case Bytecodes::_imul:
+ case Bytecodes::_fmul:
+ case Bytecodes::_idiv:
+ case Bytecodes::_fdiv:
+ case Bytecodes::_irem:
+ case Bytecodes::_frem:
+ case Bytecodes::_ishl:
+ case Bytecodes::_ishr:
+ case Bytecodes::_iushr:
+ case Bytecodes::_iand:
+ case Bytecodes::_ior:
+ case Bytecodes::_ixor:
+ case Bytecodes::_l2f:
+ case Bytecodes::_l2i:
+ case Bytecodes::_d2f:
+ case Bytecodes::_d2i:
+ case Bytecodes::_fcmpl:
+ case Bytecodes::_fcmpg:
+ case Bytecodes::_ladd:
+ case Bytecodes::_dadd:
+ case Bytecodes::_lsub:
+ case Bytecodes::_dsub:
+ case Bytecodes::_lmul:
+ case Bytecodes::_dmul:
+ case Bytecodes::_ldiv:
+ case Bytecodes::_ddiv:
+ case Bytecodes::_lrem:
+ case Bytecodes::_drem:
+ case Bytecodes::_land:
+ case Bytecodes::_lor:
+ case Bytecodes::_lxor:
+ case Bytecodes::_ineg:
+ case Bytecodes::_fneg:
+ case Bytecodes::_i2f:
+ case Bytecodes::_f2i:
+ case Bytecodes::_i2c:
+ case Bytecodes::_i2s:
+ case Bytecodes::_i2b:
+ case Bytecodes::_lneg:
+ case Bytecodes::_dneg:
+ case Bytecodes::_l2d:
+ case Bytecodes::_d2l:
+ case Bytecodes::_lshl:
+ case Bytecodes::_lshr:
+ case Bytecodes::_lushr:
+ case Bytecodes::_i2l:
+ case Bytecodes::_i2d:
+ case Bytecodes::_f2l:
+ case Bytecodes::_f2d:
+ case Bytecodes::_lcmp:
+ case Bytecodes::_dcmpl:
+ case Bytecodes::_dcmpg:
+ case Bytecodes::_ifeq:
+ case Bytecodes::_ifne:
+ case Bytecodes::_iflt:
+ case Bytecodes::_ifge:
+ case Bytecodes::_ifgt:
+ case Bytecodes::_ifle:
+ case Bytecodes::_tableswitch:
+ case Bytecodes::_ireturn:
+ case Bytecodes::_freturn:
+ case Bytecodes::_if_icmpeq:
+ case Bytecodes::_if_icmpne:
+ case Bytecodes::_if_icmplt:
+ case Bytecodes::_if_icmpge:
+ case Bytecodes::_if_icmpgt:
+ case Bytecodes::_if_icmple:
+ case Bytecodes::_lreturn:
+ case Bytecodes::_dreturn:
+ case Bytecodes::_if_acmpeq:
+ case Bytecodes::_if_acmpne:
+ case Bytecodes::_jsr:
+ case Bytecodes::_jsr_w:
+ case Bytecodes::_getstatic:
+ case Bytecodes::_putstatic:
+ case Bytecodes::_getfield:
+ case Bytecodes::_putfield:
+ case Bytecodes::_invokevirtual:
+ case Bytecodes::_invokespecial:
+ case Bytecodes::_invokestatic:
+ case Bytecodes::_invokeinterface:
+ case Bytecodes::_newarray:
+ case Bytecodes::_anewarray:
+ case Bytecodes::_checkcast:
+ case Bytecodes::_arraylength:
+ case Bytecodes::_instanceof:
+ case Bytecodes::_athrow:
+ case Bytecodes::_areturn:
+ case Bytecodes::_monitorenter:
+ case Bytecodes::_monitorexit:
+ case Bytecodes::_ifnull:
+ case Bytecodes::_ifnonnull:
+ case Bytecodes::_multianewarray:
+ case Bytecodes::_lookupswitch:
+ // These bytecodes have no effect on the method's locals.
+ break;
+
+ case Bytecodes::_return:
+ if (instruction->method()->intrinsic_id() == vmIntrinsics::_Object_init) {
+ // return from Object.init implicitly registers a finalizer
+ // for the receiver if needed, so keep it alive.
+ load_one(0);
+ }
+ break;
+
+
+ case Bytecodes::_lload:
+ case Bytecodes::_dload:
+ load_two(instruction->get_index());
+ break;
+
+ case Bytecodes::_lload_0:
+ case Bytecodes::_dload_0:
+ load_two(0);
+ break;
+
+ case Bytecodes::_lload_1:
+ case Bytecodes::_dload_1:
+ load_two(1);
+ break;
+
+ case Bytecodes::_lload_2:
+ case Bytecodes::_dload_2:
+ load_two(2);
+ break;
+
+ case Bytecodes::_lload_3:
+ case Bytecodes::_dload_3:
+ load_two(3);
+ break;
+
+ case Bytecodes::_iload:
+ case Bytecodes::_iinc:
+ case Bytecodes::_fload:
+ case Bytecodes::_aload:
+ case Bytecodes::_ret:
+ load_one(instruction->get_index());
+ break;
+
+ case Bytecodes::_iload_0:
+ case Bytecodes::_fload_0:
+ case Bytecodes::_aload_0:
+ load_one(0);
+ break;
+
+ case Bytecodes::_iload_1:
+ case Bytecodes::_fload_1:
+ case Bytecodes::_aload_1:
+ load_one(1);
+ break;
+
+ case Bytecodes::_iload_2:
+ case Bytecodes::_fload_2:
+ case Bytecodes::_aload_2:
+ load_one(2);
+ break;
+
+ case Bytecodes::_iload_3:
+ case Bytecodes::_fload_3:
+ case Bytecodes::_aload_3:
+ load_one(3);
+ break;
+
+ case Bytecodes::_lstore:
+ case Bytecodes::_dstore:
+ store_two(localNum = instruction->get_index());
+ break;
+
+ case Bytecodes::_lstore_0:
+ case Bytecodes::_dstore_0:
+ store_two(0);
+ break;
+
+ case Bytecodes::_lstore_1:
+ case Bytecodes::_dstore_1:
+ store_two(1);
+ break;
+
+ case Bytecodes::_lstore_2:
+ case Bytecodes::_dstore_2:
+ store_two(2);
+ break;
+
+ case Bytecodes::_lstore_3:
+ case Bytecodes::_dstore_3:
+ store_two(3);
+ break;
+
+ case Bytecodes::_istore:
+ case Bytecodes::_fstore:
+ case Bytecodes::_astore:
+ store_one(instruction->get_index());
+ break;
+
+ case Bytecodes::_istore_0:
+ case Bytecodes::_fstore_0:
+ case Bytecodes::_astore_0:
+ store_one(0);
+ break;
+
+ case Bytecodes::_istore_1:
+ case Bytecodes::_fstore_1:
+ case Bytecodes::_astore_1:
+ store_one(1);
+ break;
+
+ case Bytecodes::_istore_2:
+ case Bytecodes::_fstore_2:
+ case Bytecodes::_astore_2:
+ store_one(2);
+ break;
+
+ case Bytecodes::_istore_3:
+ case Bytecodes::_fstore_3:
+ case Bytecodes::_astore_3:
+ store_one(3);
+ break;
+
+ case Bytecodes::_wide:
+ fatal("Iterator should skip this bytecode");
+ break;
+
+ default:
+ tty->print("unexpected opcode: %d\n", instruction->cur_bc());
+ ShouldNotReachHere();
+ break;
+ }
+}
+
+void MethodLiveness::BasicBlock::load_two(int local) {
+ load_one(local);
+ load_one(local+1);
+}
+
+void MethodLiveness::BasicBlock::load_one(int local) {
+ if (!_kill.at(local)) {
+ _gen.at_put(local, true);
+ }
+}
+
+void MethodLiveness::BasicBlock::store_two(int local) {
+ store_one(local);
+ store_one(local+1);
+}
+
+void MethodLiveness::BasicBlock::store_one(int local) {
+ if (!_gen.at(local)) {
+ _kill.at_put(local, true);
+ }
+}
+
+void MethodLiveness::BasicBlock::propagate(MethodLiveness *ml) {
+ // These set operations could be combined for efficiency if the
+ // performance of this analysis becomes an issue.
+ _entry.set_union(_normal_exit);
+ _entry.set_difference(_kill);
+ _entry.set_union(_gen);
+
+ // Note that we merge information from our exceptional successors
+ // just once, rather than at individual bytecodes.
+ _entry.set_union(_exception_exit);
+
+ if (TraceLivenessGen) {
+ tty->print_cr(" ** Visiting block at %d **", start_bci());
+ print_on(tty);
+ }
+
+ int i;
+ for (i=_normal_predecessors->length()-1; i>=0; i--) {
+ BasicBlock *block = _normal_predecessors->at(i);
+ if (block->merge_normal(_entry)) {
+ ml->work_list_add(block);
+ }
+ }
+ for (i=_exception_predecessors->length()-1; i>=0; i--) {
+ BasicBlock *block = _exception_predecessors->at(i);
+ if (block->merge_exception(_entry)) {
+ ml->work_list_add(block);
+ }
+ }
+}
+
+bool MethodLiveness::BasicBlock::merge_normal(BitMap other) {
+ return _normal_exit.set_union_with_result(other);
+}
+
+bool MethodLiveness::BasicBlock::merge_exception(BitMap other) {
+ return _exception_exit.set_union_with_result(other);
+}
+
+MethodLivenessResult MethodLiveness::BasicBlock::get_liveness_at(ciMethod* method, int bci) {
+ MethodLivenessResult answer(NEW_RESOURCE_ARRAY(uintptr_t, _analyzer->bit_map_size_words()),
+ _analyzer->bit_map_size_bits());
+ answer.set_is_valid();
+
+#ifndef ASSERT
+ if (bci == start_bci()) {
+ answer.set_from(_entry);
+ return answer;
+ }
+#endif
+
+#ifdef ASSERT
+ ResourceMark rm;
+ BitMap g(_gen.size()); g.set_from(_gen);
+ BitMap k(_kill.size()); k.set_from(_kill);
+#endif
+ if (_last_bci != bci || trueInDebug) {
+ ciBytecodeStream bytes(method);
+ bytes.reset_to_bci(bci);
+ bytes.set_max_bci(limit_bci());
+ compute_gen_kill_range(&bytes);
+ assert(_last_bci != bci ||
+ (g.is_same(_gen) && k.is_same(_kill)), "cached computation is incorrect");
+ _last_bci = bci;
+ }
+
+ answer.clear();
+ answer.set_union(_normal_exit);
+ answer.set_difference(_kill);
+ answer.set_union(_gen);
+ answer.set_union(_exception_exit);
+
+#ifdef ASSERT
+ if (bci == start_bci()) {
+ assert(answer.is_same(_entry), "optimized answer must be accurate");
+ }
+#endif
+
+ return answer;
+}
+
+#ifndef PRODUCT
+
+void MethodLiveness::BasicBlock::print_on(outputStream *os) const {
+ os->print_cr("===================================================================");
+ os->print_cr(" Block start: %4d, limit: %4d", _start_bci, _limit_bci);
+ os->print (" Normal predecessors (%2d) @", _normal_predecessors->length());
+ int i;
+ for (i=0; i < _normal_predecessors->length(); i++) {
+ os->print(" %4d", _normal_predecessors->at(i)->start_bci());
+ }
+ os->cr();
+ os->print (" Exceptional predecessors (%2d) @", _exception_predecessors->length());
+ for (i=0; i < _exception_predecessors->length(); i++) {
+ os->print(" %4d", _exception_predecessors->at(i)->start_bci());
+ }
+ os->cr();
+ os->print (" Normal Exit : ");
+ _normal_exit.print_on(os);
+ os->print (" Gen : ");
+ _gen.print_on(os);
+ os->print (" Kill : ");
+ _kill.print_on(os);
+ os->print (" Exception Exit: ");
+ _exception_exit.print_on(os);
+ os->print (" Entry : ");
+ _entry.print_on(os);
+}
+
+#endif // PRODUCT