--- /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
+}