/* * 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_Compilation.hpp" #include "c1/c1_FrameMap.hpp" #include "c1/c1_GraphBuilder.hpp" #include "c1/c1_IR.hpp" #include "c1/c1_InstructionPrinter.hpp" #include "c1/c1_Optimizer.hpp" #include "utilities/bitMap.inline.hpp" // 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::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) , _requires_phi_function(method->max_locals()) { _caller = caller; _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; } bool IRScopeDebugInfo::should_reexecute() { ciMethod* cur_method = scope()->method(); int cur_bci = bci(); if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) { Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci); return Interpreter::bytecode_should_reexecute(code); } else return false; } // Implementation of CodeEmitInfo // Stack must be NON-null CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers) : _scope(stack->scope()) , _scope_debug_info(NULL) , _oop_map(NULL) , _stack(stack) , _exception_handlers(exception_handlers) , _is_method_handle_invoke(false) { assert(_stack != NULL, "must be non null"); } CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack) : _scope(info->_scope) , _exception_handlers(NULL) , _scope_debug_info(NULL) , _oop_map(NULL) , _stack(stack == NULL ? info->_stack : stack) , _is_method_handle_invoke(info->_is_method_handle_invoke) { // 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, true/*topmost*/, _is_method_handle_invoke); 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"); 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) { // 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 (!compilation()->profile_branches()) { 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 ValueVisitor, BlockClosure { private: void visit(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)->is_linked() && (*n)->can_be_linked()) { assert(false, "a node was not appended to the graph"); Compilation::current()->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++; } Values* worklist; int depth; enum { max_recurse_depth = 20 }; 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(this); // 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(this); } } depth--; } void block_do(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"); } UseCountComputer() { worklist = new Values(); depth = 0; } public: static void compute(BlockList* blocks) { UseCountComputer ucc; blocks->iterate_backward(&ucc); } }; // 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) Compilation* _compilation; // 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();) Compilation* compilation() const { return _compilation; } public: ComputeLinearScanOrder(Compilation* c, 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(Compilation* c, 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 _compilation(c) { TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order"); init_visited(); count_edges(start_block, NULL); if (compilation()->is_profiling()) { compilation()->method()->method_data()->set_compilation_stats(_num_loops, _num_blocks); } 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"); cur->set(BlockBegin::linear_scan_loop_header_flag); cur->set(BlockBegin::backward_branch_target_flag); parent->set(BlockBegin::linear_scan_loop_end_flag); // When a loop header is also the start of an exception handler, then the backward branch is // an exception edge. Because such edges are usually critical edges which cannot be split, the // loop must be excluded here from processing. if (cur->is_set(BlockBegin::exception_entry_flag)) { // Make sure that dominators are correct in this weird situation _iterative_dominators = true; return; } assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur, "loop end blocks must have one successor (critical edges are split)"); _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(compilation(), 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::visit(Value* v) { Value v0 = *v; if (v0) { Value vs = v0->subst(); if (vs != v0) { *v = v0->subst(); } } } #ifdef ASSERT class SubstitutionChecker: public ValueVisitor { void visit(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(this); // need to remove this instruction from the instruction stream if (n->subst() != n) { assert(last != NULL, "must have last"); last->set_next(n->next()); } else { last = n; } n = last->next(); } #ifdef ASSERT SubstitutionChecker check_substitute; 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 }