diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/c1/c1_IR.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/src/share/vm/c1/c1_IR.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,1323 @@ +/* + * Copyright 1999-2006 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. + * + */ + +# include "incls/_precompiled.incl" +# include "incls/_c1_IR.cpp.incl" + + +// Implementation of XHandlers +// +// Note: This code could eventually go away if we are +// just using the ciExceptionHandlerStream. + +XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) { + ciExceptionHandlerStream s(method); + while (!s.is_done()) { + _list.append(new XHandler(s.handler())); + s.next(); + } + assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent"); +} + +// deep copy of all XHandler contained in list +XHandlers::XHandlers(XHandlers* other) : + _list(other->length()) +{ + for (int i = 0; i < other->length(); i++) { + _list.append(new XHandler(other->handler_at(i))); + } +} + +// Returns whether a particular exception type can be caught. Also +// returns true if klass is unloaded or any exception handler +// classes are unloaded. type_is_exact indicates whether the throw +// is known to be exactly that class or it might throw a subtype. +bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const { + // the type is unknown so be conservative + if (!klass->is_loaded()) { + return true; + } + + for (int i = 0; i < length(); i++) { + XHandler* handler = handler_at(i); + if (handler->is_catch_all()) { + // catch of ANY + return true; + } + ciInstanceKlass* handler_klass = handler->catch_klass(); + // if it's unknown it might be catchable + if (!handler_klass->is_loaded()) { + return true; + } + // if the throw type is definitely a subtype of the catch type + // then it can be caught. + if (klass->is_subtype_of(handler_klass)) { + return true; + } + if (!type_is_exact) { + // If the type isn't exactly known then it can also be caught by + // catch statements where the inexact type is a subtype of the + // catch type. + // given: foo extends bar extends Exception + // throw bar can be caught by catch foo, catch bar, and catch + // Exception, however it can't be caught by any handlers without + // bar in its type hierarchy. + if (handler_klass->is_subtype_of(klass)) { + return true; + } + } + } + + return false; +} + + +bool XHandlers::equals(XHandlers* others) const { + if (others == NULL) return false; + if (length() != others->length()) return false; + + for (int i = 0; i < length(); i++) { + if (!handler_at(i)->equals(others->handler_at(i))) return false; + } + return true; +} + +bool XHandler::equals(XHandler* other) const { + assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco"); + + if (entry_pco() != other->entry_pco()) return false; + if (scope_count() != other->scope_count()) return false; + if (_desc != other->_desc) return false; + + assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal"); + return true; +} + + +// Implementation of IRScope + +BlockBegin* IRScope::header_block(BlockBegin* entry, BlockBegin::Flag f, ValueStack* state) { + if (entry == NULL) return NULL; + assert(entry->is_set(f), "entry/flag mismatch"); + // create header block + BlockBegin* h = new BlockBegin(entry->bci()); + BlockEnd* g = new Goto(entry, false); + h->set_next(g, entry->bci()); + h->set_end(g); + h->set(f); + // setup header block end state + ValueStack* s = state->copy(); // can use copy since stack is empty (=> no phis) + assert(s->stack_is_empty(), "must have empty stack at entry point"); + g->set_state(s); + return h; +} + + +BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) { + GraphBuilder gm(compilation, this); + NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats()); + if (compilation->bailed_out()) return NULL; + return gm.start(); +} + + +IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph) +: _callees(2) +, _compilation(compilation) +, _lock_stack_size(-1) +, _requires_phi_function(method->max_locals()) +{ + _caller = caller; + _caller_bci = caller == NULL ? -1 : caller_bci; + _caller_state = NULL; // Must be set later if needed + _level = caller == NULL ? 0 : caller->level() + 1; + _method = method; + _xhandlers = new XHandlers(method); + _number_of_locks = 0; + _monitor_pairing_ok = method->has_balanced_monitors(); + _start = NULL; + + if (osr_bci == -1) { + _requires_phi_function.clear(); + } else { + // selective creation of phi functions is not possibel in osr-methods + _requires_phi_function.set_range(0, method->max_locals()); + } + + assert(method->holder()->is_loaded() , "method holder must be loaded"); + + // build graph if monitor pairing is ok + if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci); +} + + +int IRScope::max_stack() const { + int my_max = method()->max_stack(); + int callee_max = 0; + for (int i = 0; i < number_of_callees(); i++) { + callee_max = MAX2(callee_max, callee_no(i)->max_stack()); + } + return my_max + callee_max; +} + + +void IRScope::compute_lock_stack_size() { + if (!InlineMethodsWithExceptionHandlers) { + _lock_stack_size = 0; + return; + } + + // Figure out whether we have to preserve expression stack elements + // for parent scopes, and if so, how many + IRScope* cur_scope = this; + while (cur_scope != NULL && !cur_scope->xhandlers()->has_handlers()) { + cur_scope = cur_scope->caller(); + } + _lock_stack_size = (cur_scope == NULL ? 0 : + (cur_scope->caller_state() == NULL ? 0 : + cur_scope->caller_state()->stack_size())); +} + +int IRScope::top_scope_bci() const { + assert(!is_top_scope(), "no correct answer for top scope possible"); + const IRScope* scope = this; + while (!scope->caller()->is_top_scope()) { + scope = scope->caller(); + } + return scope->caller_bci(); +} + + + +// Implementation of CodeEmitInfo + +// Stack must be NON-null +CodeEmitInfo::CodeEmitInfo(int bci, ValueStack* stack, XHandlers* exception_handlers) + : _scope(stack->scope()) + , _bci(bci) + , _scope_debug_info(NULL) + , _oop_map(NULL) + , _stack(stack) + , _exception_handlers(exception_handlers) + , _next(NULL) + , _id(-1) { + assert(_stack != NULL, "must be non null"); + assert(_bci == SynchronizationEntryBCI || Bytecodes::is_defined(scope()->method()->java_code_at_bci(_bci)), "make sure bci points at a real bytecode"); +} + + +CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, bool lock_stack_only) + : _scope(info->_scope) + , _exception_handlers(NULL) + , _bci(info->_bci) + , _scope_debug_info(NULL) + , _oop_map(NULL) { + if (lock_stack_only) { + if (info->_stack != NULL) { + _stack = info->_stack->copy_locks(); + } else { + _stack = NULL; + } + } else { + _stack = info->_stack; + } + + // deep copy of exception handlers + if (info->_exception_handlers != NULL) { + _exception_handlers = new XHandlers(info->_exception_handlers); + } +} + + +void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) { + // record the safepoint before recording the debug info for enclosing scopes + recorder->add_safepoint(pc_offset, _oop_map->deep_copy()); + _scope_debug_info->record_debug_info(recorder, pc_offset); + recorder->end_safepoint(pc_offset); +} + + +void CodeEmitInfo::add_register_oop(LIR_Opr opr) { + assert(_oop_map != NULL, "oop map must already exist"); + assert(opr->is_single_cpu(), "should not call otherwise"); + + int frame_size = frame_map()->framesize(); + int arg_count = frame_map()->oop_map_arg_count(); + VMReg name = frame_map()->regname(opr); + _oop_map->set_oop(name); +} + + + + +// Implementation of IR + +IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) : + _locals_size(in_WordSize(-1)) + , _num_loops(0) { + // initialize data structures + ValueType::initialize(); + Instruction::initialize(); + BlockBegin::initialize(); + GraphBuilder::initialize(); + // setup IR fields + _compilation = compilation; + _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true); + _code = NULL; +} + + +void IR::optimize() { + Optimizer opt(this); + if (DoCEE) { + opt.eliminate_conditional_expressions(); +#ifndef PRODUCT + if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); } + if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); } +#endif + } + if (EliminateBlocks) { + opt.eliminate_blocks(); +#ifndef PRODUCT + if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); } + if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); } +#endif + } + if (EliminateNullChecks) { + opt.eliminate_null_checks(); +#ifndef PRODUCT + if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); } + if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); } +#endif + } +} + + +static int sort_pairs(BlockPair** a, BlockPair** b) { + if ((*a)->from() == (*b)->from()) { + return (*a)->to()->block_id() - (*b)->to()->block_id(); + } else { + return (*a)->from()->block_id() - (*b)->from()->block_id(); + } +} + + +class CriticalEdgeFinder: public BlockClosure { + BlockPairList blocks; + IR* _ir; + + public: + CriticalEdgeFinder(IR* ir): _ir(ir) {} + void block_do(BlockBegin* bb) { + BlockEnd* be = bb->end(); + int nos = be->number_of_sux(); + if (nos >= 2) { + for (int i = 0; i < nos; i++) { + BlockBegin* sux = be->sux_at(i); + if (sux->number_of_preds() >= 2) { + blocks.append(new BlockPair(bb, sux)); + } + } + } + } + + void split_edges() { + BlockPair* last_pair = NULL; + blocks.sort(sort_pairs); + for (int i = 0; i < blocks.length(); i++) { + BlockPair* pair = blocks.at(i); + if (last_pair != NULL && pair->is_same(last_pair)) continue; + BlockBegin* from = pair->from(); + BlockBegin* to = pair->to(); + BlockBegin* split = from->insert_block_between(to); +#ifndef PRODUCT + if ((PrintIR || PrintIR1) && Verbose) { + tty->print_cr("Split critical edge B%d -> B%d (new block B%d)", + from->block_id(), to->block_id(), split->block_id()); + } +#endif + last_pair = pair; + } + } +}; + +void IR::split_critical_edges() { + CriticalEdgeFinder cef(this); + + iterate_preorder(&cef); + cef.split_edges(); +} + + +class UseCountComputer: public AllStatic { + private: + static void update_use_count(Value* n) { + // Local instructions and Phis for expression stack values at the + // start of basic blocks are not added to the instruction list + if ((*n)->bci() == -99 && (*n)->as_Local() == NULL && + (*n)->as_Phi() == NULL) { + assert(false, "a node was not appended to the graph"); + Compilation::current_compilation()->bailout("a node was not appended to the graph"); + } + // use n's input if not visited before + if (!(*n)->is_pinned() && !(*n)->has_uses()) { + // note: a) if the instruction is pinned, it will be handled by compute_use_count + // b) if the instruction has uses, it was touched before + // => in both cases we don't need to update n's values + uses_do(n); + } + // use n + (*n)->_use_count++; + } + + static Values* worklist; + static int depth; + enum { + max_recurse_depth = 20 + }; + + static void uses_do(Value* n) { + depth++; + if (depth > max_recurse_depth) { + // don't allow the traversal to recurse too deeply + worklist->push(*n); + } else { + (*n)->input_values_do(update_use_count); + // special handling for some instructions + if ((*n)->as_BlockEnd() != NULL) { + // note on BlockEnd: + // must 'use' the stack only if the method doesn't + // terminate, however, in those cases stack is empty + (*n)->state_values_do(update_use_count); + } + } + depth--; + } + + static void basic_compute_use_count(BlockBegin* b) { + depth = 0; + // process all pinned nodes as the roots of expression trees + for (Instruction* n = b; n != NULL; n = n->next()) { + if (n->is_pinned()) uses_do(&n); + } + assert(depth == 0, "should have counted back down"); + + // now process any unpinned nodes which recursed too deeply + while (worklist->length() > 0) { + Value t = worklist->pop(); + if (!t->is_pinned()) { + // compute the use count + uses_do(&t); + + // pin the instruction so that LIRGenerator doesn't recurse + // too deeply during it's evaluation. + t->pin(); + } + } + assert(depth == 0, "should have counted back down"); + } + + public: + static void compute(BlockList* blocks) { + worklist = new Values(); + blocks->blocks_do(basic_compute_use_count); + worklist = NULL; + } +}; + + +Values* UseCountComputer::worklist = NULL; +int UseCountComputer::depth = 0; + +// helper macro for short definition of trace-output inside code +#ifndef PRODUCT + #define TRACE_LINEAR_SCAN(level, code) \ + if (TraceLinearScanLevel >= level) { \ + code; \ + } +#else + #define TRACE_LINEAR_SCAN(level, code) +#endif + +class ComputeLinearScanOrder : public StackObj { + private: + int _max_block_id; // the highest block_id of a block + int _num_blocks; // total number of blocks (smaller than _max_block_id) + int _num_loops; // total number of loops + bool _iterative_dominators;// method requires iterative computation of dominatiors + + BlockList* _linear_scan_order; // the resulting list of blocks in correct order + + BitMap _visited_blocks; // used for recursive processing of blocks + BitMap _active_blocks; // used for recursive processing of blocks + BitMap _dominator_blocks; // temproary BitMap used for computation of dominator + intArray _forward_branches; // number of incoming forward branches for each block + BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges + BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop + BlockList _work_list; // temporary list (used in mark_loops and compute_order) + + // accessors for _visited_blocks and _active_blocks + void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); } + bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); } + bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); } + void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); } + void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); } + void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); } + + // accessors for _forward_branches + void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); } + int dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); } + + // accessors for _loop_map + bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); } + void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); } + void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); } + + // count edges between blocks + void count_edges(BlockBegin* cur, BlockBegin* parent); + + // loop detection + void mark_loops(); + void clear_non_natural_loops(BlockBegin* start_block); + void assign_loop_depth(BlockBegin* start_block); + + // computation of final block order + BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b); + void compute_dominator(BlockBegin* cur, BlockBegin* parent); + int compute_weight(BlockBegin* cur); + bool ready_for_processing(BlockBegin* cur); + void sort_into_work_list(BlockBegin* b); + void append_block(BlockBegin* cur); + void compute_order(BlockBegin* start_block); + + // fixup of dominators for non-natural loops + bool compute_dominators_iter(); + void compute_dominators(); + + // debug functions + NOT_PRODUCT(void print_blocks();) + DEBUG_ONLY(void verify();) + + public: + ComputeLinearScanOrder(BlockBegin* start_block); + + // accessors for final result + BlockList* linear_scan_order() const { return _linear_scan_order; } + int num_loops() const { return _num_loops; } +}; + + +ComputeLinearScanOrder::ComputeLinearScanOrder(BlockBegin* start_block) : + _max_block_id(BlockBegin::number_of_blocks()), + _num_blocks(0), + _num_loops(0), + _iterative_dominators(false), + _visited_blocks(_max_block_id), + _active_blocks(_max_block_id), + _dominator_blocks(_max_block_id), + _forward_branches(_max_block_id, 0), + _loop_end_blocks(8), + _work_list(8), + _linear_scan_order(NULL), // initialized later with correct size + _loop_map(0, 0) // initialized later with correct size +{ + TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order"); + + init_visited(); + count_edges(start_block, NULL); + + if (_num_loops > 0) { + mark_loops(); + clear_non_natural_loops(start_block); + assign_loop_depth(start_block); + } + + compute_order(start_block); + compute_dominators(); + + NOT_PRODUCT(print_blocks()); + DEBUG_ONLY(verify()); +} + + +// Traverse the CFG: +// * count total number of blocks +// * count all incoming edges and backward incoming edges +// * number loop header blocks +// * create a list with all loop end blocks +void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) { + TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != NULL ? parent->block_id() : -1)); + assert(cur->dominator() == NULL, "dominator already initialized"); + + if (is_active(cur)) { + TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch")); + assert(is_visited(cur), "block must be visisted when block is active"); + assert(parent != NULL, "must have parent"); + assert(parent->number_of_sux() == 1, "loop end blocks must have one successor (critical edges are split)"); + + cur->set(BlockBegin::linear_scan_loop_header_flag); + cur->set(BlockBegin::backward_branch_target_flag); + + parent->set(BlockBegin::linear_scan_loop_end_flag); + _loop_end_blocks.append(parent); + return; + } + + // increment number of incoming forward branches + inc_forward_branches(cur); + + if (is_visited(cur)) { + TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited")); + return; + } + + _num_blocks++; + set_visited(cur); + set_active(cur); + + // recursive call for all successors + int i; + for (i = cur->number_of_sux() - 1; i >= 0; i--) { + count_edges(cur->sux_at(i), cur); + } + for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { + count_edges(cur->exception_handler_at(i), cur); + } + + clear_active(cur); + + // Each loop has a unique number. + // When multiple loops are nested, assign_loop_depth assumes that the + // innermost loop has the lowest number. This is guaranteed by setting + // the loop number after the recursive calls for the successors above + // have returned. + if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) { + assert(cur->loop_index() == -1, "cannot set loop-index twice"); + TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops)); + + cur->set_loop_index(_num_loops); + _num_loops++; + } + + TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id())); +} + + +void ComputeLinearScanOrder::mark_loops() { + TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops")); + + _loop_map = BitMap2D(_num_loops, _max_block_id); + _loop_map.clear(); + + for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) { + BlockBegin* loop_end = _loop_end_blocks.at(i); + BlockBegin* loop_start = loop_end->sux_at(0); + int loop_idx = loop_start->loop_index(); + + TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx)); + assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set"); + assert(loop_end->number_of_sux() == 1, "incorrect number of successors"); + assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set"); + assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set"); + assert(_work_list.is_empty(), "work list must be empty before processing"); + + // add the end-block of the loop to the working list + _work_list.push(loop_end); + set_block_in_loop(loop_idx, loop_end); + do { + BlockBegin* cur = _work_list.pop(); + + TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id())); + assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list"); + + // recursive processing of all predecessors ends when start block of loop is reached + if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) { + for (int j = cur->number_of_preds() - 1; j >= 0; j--) { + BlockBegin* pred = cur->pred_at(j); + + if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) { + // this predecessor has not been processed yet, so add it to work list + TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id())); + _work_list.push(pred); + set_block_in_loop(loop_idx, pred); + } + } + } + } while (!_work_list.is_empty()); + } +} + + +// check for non-natural loops (loops where the loop header does not dominate +// all other loop blocks = loops with mulitple entries). +// such loops are ignored +void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) { + for (int i = _num_loops - 1; i >= 0; i--) { + if (is_block_in_loop(i, start_block)) { + // loop i contains the entry block of the method + // -> this is not a natural loop, so ignore it + TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i)); + + for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) { + clear_block_in_loop(i, block_id); + } + _iterative_dominators = true; + } + } +} + +void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) { + TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight"); + init_visited(); + + assert(_work_list.is_empty(), "work list must be empty before processing"); + _work_list.append(start_block); + + do { + BlockBegin* cur = _work_list.pop(); + + if (!is_visited(cur)) { + set_visited(cur); + TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id())); + + // compute loop-depth and loop-index for the block + assert(cur->loop_depth() == 0, "cannot set loop-depth twice"); + int i; + int loop_depth = 0; + int min_loop_idx = -1; + for (i = _num_loops - 1; i >= 0; i--) { + if (is_block_in_loop(i, cur)) { + loop_depth++; + min_loop_idx = i; + } + } + cur->set_loop_depth(loop_depth); + cur->set_loop_index(min_loop_idx); + + // append all unvisited successors to work list + for (i = cur->number_of_sux() - 1; i >= 0; i--) { + _work_list.append(cur->sux_at(i)); + } + for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) { + _work_list.append(cur->exception_handler_at(i)); + } + } + } while (!_work_list.is_empty()); +} + + +BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) { + assert(a != NULL && b != NULL, "must have input blocks"); + + _dominator_blocks.clear(); + while (a != NULL) { + _dominator_blocks.set_bit(a->block_id()); + assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized"); + a = a->dominator(); + } + while (b != NULL && !_dominator_blocks.at(b->block_id())) { + assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized"); + b = b->dominator(); + } + + assert(b != NULL, "could not find dominator"); + return b; +} + +void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) { + if (cur->dominator() == NULL) { + TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id())); + cur->set_dominator(parent); + + } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) { + TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id())); + assert(cur->number_of_preds() > 1, ""); + cur->set_dominator(common_dominator(cur->dominator(), parent)); + } +} + + +int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) { + BlockBegin* single_sux = NULL; + if (cur->number_of_sux() == 1) { + single_sux = cur->sux_at(0); + } + + // limit loop-depth to 15 bit (only for security reason, it will never be so big) + int weight = (cur->loop_depth() & 0x7FFF) << 16; + + // general macro for short definition of weight flags + // the first instance of INC_WEIGHT_IF has the highest priority + int cur_bit = 15; + #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--; + + // this is necessery for the (very rare) case that two successing blocks have + // the same loop depth, but a different loop index (can happen for endless loops + // with exception handlers) + INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag)); + + // loop end blocks (blocks that end with a backward branch) are added + // after all other blocks of the loop. + INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag)); + + // critical edge split blocks are prefered because than they have a bigger + // proability to be completely empty + INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag)); + + // exceptions should not be thrown in normal control flow, so these blocks + // are added as late as possible + INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL)); + INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL)); + + // exceptions handlers are added as late as possible + INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag)); + + // guarantee that weight is > 0 + weight |= 1; + + #undef INC_WEIGHT_IF + assert(cur_bit >= 0, "too many flags"); + assert(weight > 0, "weight cannot become negative"); + + return weight; +} + +bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) { + // Discount the edge just traveled. + // When the number drops to zero, all forward branches were processed + if (dec_forward_branches(cur) != 0) { + return false; + } + + assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)"); + assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)"); + return true; +} + +void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) { + assert(_work_list.index_of(cur) == -1, "block already in work list"); + + int cur_weight = compute_weight(cur); + + // the linear_scan_number is used to cache the weight of a block + cur->set_linear_scan_number(cur_weight); + +#ifndef PRODUCT + if (StressLinearScan) { + _work_list.insert_before(0, cur); + return; + } +#endif + + _work_list.append(NULL); // provide space for new element + + int insert_idx = _work_list.length() - 1; + while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) { + _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1)); + insert_idx--; + } + _work_list.at_put(insert_idx, cur); + + TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id())); + TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number())); + +#ifdef ASSERT + for (int i = 0; i < _work_list.length(); i++) { + assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set"); + assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist"); + } +#endif +} + +void ComputeLinearScanOrder::append_block(BlockBegin* cur) { + TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number())); + assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice"); + + // currently, the linear scan order and code emit order are equal. + // therefore the linear_scan_number and the weight of a block must also + // be equal. + cur->set_linear_scan_number(_linear_scan_order->length()); + _linear_scan_order->append(cur); +} + +void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) { + TRACE_LINEAR_SCAN(3, "----- computing final block order"); + + // the start block is always the first block in the linear scan order + _linear_scan_order = new BlockList(_num_blocks); + append_block(start_block); + + assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction"); + BlockBegin* std_entry = ((Base*)start_block->end())->std_entry(); + BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry(); + + BlockBegin* sux_of_osr_entry = NULL; + if (osr_entry != NULL) { + // special handling for osr entry: + // ignore the edge between the osr entry and its successor for processing + // the osr entry block is added manually below + assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor"); + assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow"); + + sux_of_osr_entry = osr_entry->sux_at(0); + dec_forward_branches(sux_of_osr_entry); + + compute_dominator(osr_entry, start_block); + _iterative_dominators = true; + } + compute_dominator(std_entry, start_block); + + // start processing with standard entry block + assert(_work_list.is_empty(), "list must be empty before processing"); + + if (ready_for_processing(std_entry)) { + sort_into_work_list(std_entry); + } else { + assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)"); + } + + do { + BlockBegin* cur = _work_list.pop(); + + if (cur == sux_of_osr_entry) { + // the osr entry block is ignored in normal processing, it is never added to the + // work list. Instead, it is added as late as possible manually here. + append_block(osr_entry); + compute_dominator(cur, osr_entry); + } + append_block(cur); + + int i; + int num_sux = cur->number_of_sux(); + // changed loop order to get "intuitive" order of if- and else-blocks + for (i = 0; i < num_sux; i++) { + BlockBegin* sux = cur->sux_at(i); + compute_dominator(sux, cur); + if (ready_for_processing(sux)) { + sort_into_work_list(sux); + } + } + num_sux = cur->number_of_exception_handlers(); + for (i = 0; i < num_sux; i++) { + BlockBegin* sux = cur->exception_handler_at(i); + compute_dominator(sux, cur); + if (ready_for_processing(sux)) { + sort_into_work_list(sux); + } + } + } while (_work_list.length() > 0); +} + + +bool ComputeLinearScanOrder::compute_dominators_iter() { + bool changed = false; + int num_blocks = _linear_scan_order->length(); + + assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator"); + assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors"); + for (int i = 1; i < num_blocks; i++) { + BlockBegin* block = _linear_scan_order->at(i); + + BlockBegin* dominator = block->pred_at(0); + int num_preds = block->number_of_preds(); + for (int i = 1; i < num_preds; i++) { + dominator = common_dominator(dominator, block->pred_at(i)); + } + + if (dominator != block->dominator()) { + TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id())); + + block->set_dominator(dominator); + changed = true; + } + } + return changed; +} + +void ComputeLinearScanOrder::compute_dominators() { + TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators)); + + // iterative computation of dominators is only required for methods with non-natural loops + // and OSR-methods. For all other methods, the dominators computed when generating the + // linear scan block order are correct. + if (_iterative_dominators) { + do { + TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation")); + } while (compute_dominators_iter()); + } + + // check that dominators are correct + assert(!compute_dominators_iter(), "fix point not reached"); +} + + +#ifndef PRODUCT +void ComputeLinearScanOrder::print_blocks() { + if (TraceLinearScanLevel >= 2) { + tty->print_cr("----- loop information:"); + for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { + BlockBegin* cur = _linear_scan_order->at(block_idx); + + tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id()); + for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { + tty->print ("%d ", is_block_in_loop(loop_idx, cur)); + } + tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth()); + } + } + + if (TraceLinearScanLevel >= 1) { + tty->print_cr("----- linear-scan block order:"); + for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) { + BlockBegin* cur = _linear_scan_order->at(block_idx); + tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth()); + + tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " "); + tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " "); + tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " "); + tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " "); + + if (cur->dominator() != NULL) { + tty->print(" dom: B%d ", cur->dominator()->block_id()); + } else { + tty->print(" dom: NULL "); + } + + if (cur->number_of_preds() > 0) { + tty->print(" preds: "); + for (int j = 0; j < cur->number_of_preds(); j++) { + BlockBegin* pred = cur->pred_at(j); + tty->print("B%d ", pred->block_id()); + } + } + if (cur->number_of_sux() > 0) { + tty->print(" sux: "); + for (int j = 0; j < cur->number_of_sux(); j++) { + BlockBegin* sux = cur->sux_at(j); + tty->print("B%d ", sux->block_id()); + } + } + if (cur->number_of_exception_handlers() > 0) { + tty->print(" ex: "); + for (int j = 0; j < cur->number_of_exception_handlers(); j++) { + BlockBegin* ex = cur->exception_handler_at(j); + tty->print("B%d ", ex->block_id()); + } + } + tty->cr(); + } + } +} +#endif + +#ifdef ASSERT +void ComputeLinearScanOrder::verify() { + assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list"); + + if (StressLinearScan) { + // blocks are scrambled when StressLinearScan is used + return; + } + + // check that all successors of a block have a higher linear-scan-number + // and that all predecessors of a block have a lower linear-scan-number + // (only backward branches of loops are ignored) + int i; + for (i = 0; i < _linear_scan_order->length(); i++) { + BlockBegin* cur = _linear_scan_order->at(i); + + assert(cur->linear_scan_number() == i, "incorrect linear_scan_number"); + assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number"); + + int j; + for (j = cur->number_of_sux() - 1; j >= 0; j--) { + BlockBegin* sux = cur->sux_at(j); + + assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number"); + if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) { + assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order"); + } + if (cur->loop_depth() == sux->loop_depth()) { + assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index"); + } + } + + for (j = cur->number_of_preds() - 1; j >= 0; j--) { + BlockBegin* pred = cur->pred_at(j); + + assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number"); + if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) { + assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order"); + } + if (cur->loop_depth() == pred->loop_depth()) { + assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index"); + } + + assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors"); + } + + // check dominator + if (i == 0) { + assert(cur->dominator() == NULL, "first block has no dominator"); + } else { + assert(cur->dominator() != NULL, "all but first block must have dominator"); + } + assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator"); + } + + // check that all loops are continuous + for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) { + int block_idx = 0; + assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop"); + + // skip blocks before the loop + while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { + block_idx++; + } + // skip blocks of loop + while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) { + block_idx++; + } + // after the first non-loop block, there must not be another loop-block + while (block_idx < _num_blocks) { + assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order"); + block_idx++; + } + } +} +#endif + + +void IR::compute_code() { + assert(is_valid(), "IR must be valid"); + + ComputeLinearScanOrder compute_order(start()); + _num_loops = compute_order.num_loops(); + _code = compute_order.linear_scan_order(); +} + + +void IR::compute_use_counts() { + // make sure all values coming out of this block get evaluated. + int num_blocks = _code->length(); + for (int i = 0; i < num_blocks; i++) { + _code->at(i)->end()->state()->pin_stack_for_linear_scan(); + } + + // compute use counts + UseCountComputer::compute(_code); +} + + +void IR::iterate_preorder(BlockClosure* closure) { + assert(is_valid(), "IR must be valid"); + start()->iterate_preorder(closure); +} + + +void IR::iterate_postorder(BlockClosure* closure) { + assert(is_valid(), "IR must be valid"); + start()->iterate_postorder(closure); +} + +void IR::iterate_linear_scan_order(BlockClosure* closure) { + linear_scan_order()->iterate_forward(closure); +} + + +#ifndef PRODUCT +class BlockPrinter: public BlockClosure { + private: + InstructionPrinter* _ip; + bool _cfg_only; + bool _live_only; + + public: + BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) { + _ip = ip; + _cfg_only = cfg_only; + _live_only = live_only; + } + + virtual void block_do(BlockBegin* block) { + if (_cfg_only) { + _ip->print_instr(block); tty->cr(); + } else { + block->print_block(*_ip, _live_only); + } + } +}; + + +void IR::print(BlockBegin* start, bool cfg_only, bool live_only) { + ttyLocker ttyl; + InstructionPrinter ip(!cfg_only); + BlockPrinter bp(&ip, cfg_only, live_only); + start->iterate_preorder(&bp); + tty->cr(); +} + +void IR::print(bool cfg_only, bool live_only) { + if (is_valid()) { + print(start(), cfg_only, live_only); + } else { + tty->print_cr("invalid IR"); + } +} + + +define_array(BlockListArray, BlockList*) +define_stack(BlockListList, BlockListArray) + +class PredecessorValidator : public BlockClosure { + private: + BlockListList* _predecessors; + BlockList* _blocks; + + static int cmp(BlockBegin** a, BlockBegin** b) { + return (*a)->block_id() - (*b)->block_id(); + } + + public: + PredecessorValidator(IR* hir) { + ResourceMark rm; + _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL); + _blocks = new BlockList(); + + int i; + hir->start()->iterate_preorder(this); + if (hir->code() != NULL) { + assert(hir->code()->length() == _blocks->length(), "must match"); + for (i = 0; i < _blocks->length(); i++) { + assert(hir->code()->contains(_blocks->at(i)), "should be in both lists"); + } + } + + for (i = 0; i < _blocks->length(); i++) { + BlockBegin* block = _blocks->at(i); + BlockList* preds = _predecessors->at(block->block_id()); + if (preds == NULL) { + assert(block->number_of_preds() == 0, "should be the same"); + continue; + } + + // clone the pred list so we can mutate it + BlockList* pred_copy = new BlockList(); + int j; + for (j = 0; j < block->number_of_preds(); j++) { + pred_copy->append(block->pred_at(j)); + } + // sort them in the same order + preds->sort(cmp); + pred_copy->sort(cmp); + int length = MIN2(preds->length(), block->number_of_preds()); + for (j = 0; j < block->number_of_preds(); j++) { + assert(preds->at(j) == pred_copy->at(j), "must match"); + } + + assert(preds->length() == block->number_of_preds(), "should be the same"); + } + } + + virtual void block_do(BlockBegin* block) { + _blocks->append(block); + BlockEnd* be = block->end(); + int n = be->number_of_sux(); + int i; + for (i = 0; i < n; i++) { + BlockBegin* sux = be->sux_at(i); + assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler"); + + BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL); + if (preds == NULL) { + preds = new BlockList(); + _predecessors->at_put(sux->block_id(), preds); + } + preds->append(block); + } + + n = block->number_of_exception_handlers(); + for (i = 0; i < n; i++) { + BlockBegin* sux = block->exception_handler_at(i); + assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler"); + + BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL); + if (preds == NULL) { + preds = new BlockList(); + _predecessors->at_put(sux->block_id(), preds); + } + preds->append(block); + } + } +}; + +void IR::verify() { +#ifdef ASSERT + PredecessorValidator pv(this); +#endif +} + +#endif // PRODUCT + +void SubstitutionResolver::substitute(Value* v) { + Value v0 = *v; + if (v0) { + Value vs = v0->subst(); + if (vs != v0) { + *v = v0->subst(); + } + } +} + +#ifdef ASSERT +void check_substitute(Value* v) { + Value v0 = *v; + if (v0) { + Value vs = v0->subst(); + assert(vs == v0, "missed substitution"); + } +} +#endif + + +void SubstitutionResolver::block_do(BlockBegin* block) { + Instruction* last = NULL; + for (Instruction* n = block; n != NULL;) { + n->values_do(substitute); + // need to remove this instruction from the instruction stream + if (n->subst() != n) { + assert(last != NULL, "must have last"); + last->set_next(n->next(), n->next()->bci()); + } else { + last = n; + } + n = last->next(); + } + +#ifdef ASSERT + if (block->state()) block->state()->values_do(check_substitute); + block->block_values_do(check_substitute); + if (block->end() && block->end()->state()) block->end()->state()->values_do(check_substitute); +#endif +}