| /* |
| * 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_Optimizer.cpp.incl" |
| |
| define_array(ValueSetArray, ValueSet*); |
| define_stack(ValueSetList, ValueSetArray); |
| |
| |
| Optimizer::Optimizer(IR* ir) { |
| assert(ir->is_valid(), "IR must be valid"); |
| _ir = ir; |
| } |
| |
| class CE_Eliminator: public BlockClosure { |
| private: |
| IR* _hir; |
| int _cee_count; // the number of CEs successfully eliminated |
| int _has_substitution; |
| |
| public: |
| CE_Eliminator(IR* hir) : _cee_count(0), _hir(hir) { |
| _has_substitution = false; |
| _hir->iterate_preorder(this); |
| if (_has_substitution) { |
| // substituted some phis so resolve the substitution |
| SubstitutionResolver sr(_hir); |
| } |
| } |
| int cee_count() const { return _cee_count; } |
| |
| void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { |
| int e = sux->number_of_exception_handlers(); |
| for (int i = 0; i < e; i++) { |
| BlockBegin* xhandler = sux->exception_handler_at(i); |
| block->add_exception_handler(xhandler); |
| |
| assert(xhandler->is_predecessor(sux), "missing predecessor"); |
| if (sux->number_of_preds() == 0) { |
| // sux is disconnected from graph so disconnect from exception handlers |
| xhandler->remove_predecessor(sux); |
| } |
| if (!xhandler->is_predecessor(block)) { |
| xhandler->add_predecessor(block); |
| } |
| } |
| } |
| |
| virtual void block_do(BlockBegin* block) { |
| // 1) find conditional expression |
| // check if block ends with an If |
| If* if_ = block->end()->as_If(); |
| if (if_ == NULL) return; |
| |
| // check if If works on int or object types |
| // (we cannot handle If's working on long, float or doubles yet, |
| // since IfOp doesn't support them - these If's show up if cmp |
| // operations followed by If's are eliminated) |
| ValueType* if_type = if_->x()->type(); |
| if (!if_type->is_int() && !if_type->is_object()) return; |
| |
| BlockBegin* t_block = if_->tsux(); |
| BlockBegin* f_block = if_->fsux(); |
| Instruction* t_cur = t_block->next(); |
| Instruction* f_cur = f_block->next(); |
| |
| // one Constant may be present between BlockBegin and BlockEnd |
| Value t_const = NULL; |
| Value f_const = NULL; |
| if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { |
| t_const = t_cur; |
| t_cur = t_cur->next(); |
| } |
| if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { |
| f_const = f_cur; |
| f_cur = f_cur->next(); |
| } |
| |
| // check if both branches end with a goto |
| Goto* t_goto = t_cur->as_Goto(); |
| if (t_goto == NULL) return; |
| Goto* f_goto = f_cur->as_Goto(); |
| if (f_goto == NULL) return; |
| |
| // check if both gotos merge into the same block |
| BlockBegin* sux = t_goto->default_sux(); |
| if (sux != f_goto->default_sux()) return; |
| |
| // check if at least one word was pushed on sux_state |
| ValueStack* sux_state = sux->state(); |
| if (sux_state->stack_size() <= if_->state()->stack_size()) return; |
| |
| // check if phi function is present at end of successor stack and that |
| // only this phi was pushed on the stack |
| Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); |
| if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; |
| if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; |
| |
| // get the values that were pushed in the true- and false-branch |
| Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); |
| Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); |
| |
| // backend does not support floats |
| assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); |
| if (t_value->type()->is_float_kind()) return; |
| |
| // check that successor has no other phi functions but sux_phi |
| // this can happen when t_block or f_block contained additonal stores to local variables |
| // that are no longer represented by explicit instructions |
| for_each_phi_fun(sux, phi, |
| if (phi != sux_phi) return; |
| ); |
| // true and false blocks can't have phis |
| for_each_phi_fun(t_block, phi, return; ); |
| for_each_phi_fun(f_block, phi, return; ); |
| |
| // 2) substitute conditional expression |
| // with an IfOp followed by a Goto |
| // cut if_ away and get node before |
| Instruction* cur_end = if_->prev(block); |
| int bci = if_->bci(); |
| |
| // append constants of true- and false-block if necessary |
| // clone constants because original block must not be destroyed |
| assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); |
| if (t_value == t_const) { |
| t_value = new Constant(t_const->type()); |
| cur_end = cur_end->set_next(t_value, bci); |
| } |
| if (f_value == f_const) { |
| f_value = new Constant(f_const->type()); |
| cur_end = cur_end->set_next(f_value, bci); |
| } |
| |
| // it is very unlikely that the condition can be statically decided |
| // (this was checked previously by the Canonicalizer), so always |
| // append IfOp |
| Value result = new IfOp(if_->x(), if_->cond(), if_->y(), t_value, f_value); |
| cur_end = cur_end->set_next(result, bci); |
| |
| // append Goto to successor |
| ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; |
| Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); |
| |
| // prepare state for Goto |
| ValueStack* goto_state = if_->state(); |
| while (sux_state->scope() != goto_state->scope()) { |
| goto_state = goto_state->pop_scope(); |
| assert(goto_state != NULL, "states do not match up"); |
| } |
| goto_state = goto_state->copy(); |
| goto_state->push(result->type(), result); |
| assert(goto_state->is_same_across_scopes(sux_state), "states must match now"); |
| goto_->set_state(goto_state); |
| |
| // Steal the bci for the goto from the sux |
| cur_end = cur_end->set_next(goto_, sux->bci()); |
| |
| // Adjust control flow graph |
| BlockBegin::disconnect_edge(block, t_block); |
| BlockBegin::disconnect_edge(block, f_block); |
| if (t_block->number_of_preds() == 0) { |
| BlockBegin::disconnect_edge(t_block, sux); |
| } |
| adjust_exception_edges(block, t_block); |
| if (f_block->number_of_preds() == 0) { |
| BlockBegin::disconnect_edge(f_block, sux); |
| } |
| adjust_exception_edges(block, f_block); |
| |
| // update block end |
| block->set_end(goto_); |
| |
| // substitute the phi if possible |
| if (sux_phi->as_Phi()->operand_count() == 1) { |
| assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); |
| sux_phi->set_subst(result); |
| _has_substitution = true; |
| } |
| |
| // 3) successfully eliminated a conditional expression |
| _cee_count++; |
| if (PrintCEE) { |
| tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id()); |
| } |
| |
| _hir->verify(); |
| } |
| }; |
| |
| |
| void Optimizer::eliminate_conditional_expressions() { |
| // find conditional expressions & replace them with IfOps |
| CE_Eliminator ce(ir()); |
| } |
| |
| |
| class BlockMerger: public BlockClosure { |
| private: |
| IR* _hir; |
| int _merge_count; // the number of block pairs successfully merged |
| |
| public: |
| BlockMerger(IR* hir) |
| : _hir(hir) |
| , _merge_count(0) |
| { |
| _hir->iterate_preorder(this); |
| } |
| |
| bool try_merge(BlockBegin* block) { |
| BlockEnd* end = block->end(); |
| if (end->as_Goto() != NULL) { |
| assert(end->number_of_sux() == 1, "end must have exactly one successor"); |
| // Note: It would be sufficient to check for the number of successors (= 1) |
| // in order to decide if this block can be merged potentially. That |
| // would then also include switch statements w/ only a default case. |
| // However, in that case we would need to make sure the switch tag |
| // expression is executed if it can produce observable side effects. |
| // We should probably have the canonicalizer simplifying such switch |
| // statements and then we are sure we don't miss these merge opportunities |
| // here (was bug - gri 7/7/99). |
| BlockBegin* sux = end->default_sux(); |
| if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { |
| // merge the two blocks |
| |
| #ifdef ASSERT |
| // verify that state at the end of block and at the beginning of sux are equal |
| // no phi functions must be present at beginning of sux |
| ValueStack* sux_state = sux->state(); |
| ValueStack* end_state = end->state(); |
| while (end_state->scope() != sux_state->scope()) { |
| // match up inlining level |
| end_state = end_state->pop_scope(); |
| } |
| assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); |
| assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); |
| |
| int index; |
| Value sux_value; |
| for_each_stack_value(sux_state, index, sux_value) { |
| assert(sux_value == end_state->stack_at(index), "stack not equal"); |
| } |
| for_each_local_value(sux_state, index, sux_value) { |
| assert(sux_value == end_state->local_at(index), "locals not equal"); |
| } |
| assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); |
| #endif |
| |
| // find instruction before end & append first instruction of sux block |
| Instruction* prev = end->prev(block); |
| Instruction* next = sux->next(); |
| assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); |
| prev->set_next(next, next->bci()); |
| sux->disconnect_from_graph(); |
| block->set_end(sux->end()); |
| // add exception handlers of deleted block, if any |
| for (int k = 0; k < sux->number_of_exception_handlers(); k++) { |
| BlockBegin* xhandler = sux->exception_handler_at(k); |
| block->add_exception_handler(xhandler); |
| |
| // also substitute predecessor of exception handler |
| assert(xhandler->is_predecessor(sux), "missing predecessor"); |
| xhandler->remove_predecessor(sux); |
| if (!xhandler->is_predecessor(block)) { |
| xhandler->add_predecessor(block); |
| } |
| } |
| |
| // debugging output |
| _merge_count++; |
| if (PrintBlockElimination) { |
| tty->print_cr("%d. merged B%d & B%d (stack size = %d)", |
| _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); |
| } |
| |
| _hir->verify(); |
| |
| If* if_ = block->end()->as_If(); |
| if (if_) { |
| IfOp* ifop = if_->x()->as_IfOp(); |
| Constant* con = if_->y()->as_Constant(); |
| bool swapped = false; |
| if (!con || !ifop) { |
| ifop = if_->y()->as_IfOp(); |
| con = if_->x()->as_Constant(); |
| swapped = true; |
| } |
| if (con && ifop) { |
| Constant* tval = ifop->tval()->as_Constant(); |
| Constant* fval = ifop->fval()->as_Constant(); |
| if (tval && fval) { |
| // Find the instruction before if_, starting with ifop. |
| // When if_ and ifop are not in the same block, prev |
| // becomes NULL In such (rare) cases it is not |
| // profitable to perform the optimization. |
| Value prev = ifop; |
| while (prev != NULL && prev->next() != if_) { |
| prev = prev->next(); |
| } |
| |
| if (prev != NULL) { |
| Instruction::Condition cond = if_->cond(); |
| BlockBegin* tsux = if_->tsux(); |
| BlockBegin* fsux = if_->fsux(); |
| if (swapped) { |
| cond = Instruction::mirror(cond); |
| tsux = if_->fsux(); |
| fsux = if_->tsux(); |
| } |
| |
| BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); |
| BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); |
| if (tblock != fblock && !if_->is_safepoint()) { |
| If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), |
| tblock, fblock, if_->state_before(), if_->is_safepoint()); |
| newif->set_state(if_->state()->copy()); |
| |
| assert(prev->next() == if_, "must be guaranteed by above search"); |
| prev->set_next(newif, if_->bci()); |
| block->set_end(newif); |
| |
| _merge_count++; |
| if (PrintBlockElimination) { |
| tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); |
| } |
| |
| _hir->verify(); |
| } |
| } |
| } |
| } |
| } |
| |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| virtual void block_do(BlockBegin* block) { |
| _hir->verify(); |
| // repeat since the same block may merge again |
| while (try_merge(block)) { |
| _hir->verify(); |
| } |
| } |
| }; |
| |
| |
| void Optimizer::eliminate_blocks() { |
| // merge blocks if possible |
| BlockMerger bm(ir()); |
| } |
| |
| |
| class NullCheckEliminator; |
| class NullCheckVisitor: public InstructionVisitor { |
| private: |
| NullCheckEliminator* _nce; |
| NullCheckEliminator* nce() { return _nce; } |
| |
| public: |
| NullCheckVisitor() {} |
| |
| void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } |
| |
| void do_Phi (Phi* x); |
| void do_Local (Local* x); |
| void do_Constant (Constant* x); |
| void do_LoadField (LoadField* x); |
| void do_StoreField (StoreField* x); |
| void do_ArrayLength (ArrayLength* x); |
| void do_LoadIndexed (LoadIndexed* x); |
| void do_StoreIndexed (StoreIndexed* x); |
| void do_NegateOp (NegateOp* x); |
| void do_ArithmeticOp (ArithmeticOp* x); |
| void do_ShiftOp (ShiftOp* x); |
| void do_LogicOp (LogicOp* x); |
| void do_CompareOp (CompareOp* x); |
| void do_IfOp (IfOp* x); |
| void do_Convert (Convert* x); |
| void do_NullCheck (NullCheck* x); |
| void do_Invoke (Invoke* x); |
| void do_NewInstance (NewInstance* x); |
| void do_NewTypeArray (NewTypeArray* x); |
| void do_NewObjectArray (NewObjectArray* x); |
| void do_NewMultiArray (NewMultiArray* x); |
| void do_CheckCast (CheckCast* x); |
| void do_InstanceOf (InstanceOf* x); |
| void do_MonitorEnter (MonitorEnter* x); |
| void do_MonitorExit (MonitorExit* x); |
| void do_Intrinsic (Intrinsic* x); |
| void do_BlockBegin (BlockBegin* x); |
| void do_Goto (Goto* x); |
| void do_If (If* x); |
| void do_IfInstanceOf (IfInstanceOf* x); |
| void do_TableSwitch (TableSwitch* x); |
| void do_LookupSwitch (LookupSwitch* x); |
| void do_Return (Return* x); |
| void do_Throw (Throw* x); |
| void do_Base (Base* x); |
| void do_OsrEntry (OsrEntry* x); |
| void do_ExceptionObject(ExceptionObject* x); |
| void do_RoundFP (RoundFP* x); |
| void do_UnsafeGetRaw (UnsafeGetRaw* x); |
| void do_UnsafePutRaw (UnsafePutRaw* x); |
| void do_UnsafeGetObject(UnsafeGetObject* x); |
| void do_UnsafePutObject(UnsafePutObject* x); |
| void do_UnsafePrefetchRead (UnsafePrefetchRead* x); |
| void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); |
| void do_ProfileCall (ProfileCall* x); |
| void do_ProfileCounter (ProfileCounter* x); |
| }; |
| |
| |
| // Because of a static contained within (for the purpose of iteration |
| // over instructions), it is only valid to have one of these active at |
| // a time |
| class NullCheckEliminator { |
| private: |
| static NullCheckEliminator* _static_nce; |
| static void do_value(Value* vp); |
| |
| Optimizer* _opt; |
| |
| ValueSet* _visitable_instructions; // Visit each instruction only once per basic block |
| BlockList* _work_list; // Basic blocks to visit |
| |
| bool visitable(Value x) { |
| assert(_visitable_instructions != NULL, "check"); |
| return _visitable_instructions->contains(x); |
| } |
| void mark_visited(Value x) { |
| assert(_visitable_instructions != NULL, "check"); |
| _visitable_instructions->remove(x); |
| } |
| void mark_visitable(Value x) { |
| assert(_visitable_instructions != NULL, "check"); |
| _visitable_instructions->put(x); |
| } |
| void clear_visitable_state() { |
| assert(_visitable_instructions != NULL, "check"); |
| _visitable_instructions->clear(); |
| } |
| |
| ValueSet* _set; // current state, propagated to subsequent BlockBegins |
| ValueSetList _block_states; // BlockBegin null-check states for all processed blocks |
| NullCheckVisitor _visitor; |
| NullCheck* _last_explicit_null_check; |
| |
| bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } |
| void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } |
| void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } |
| |
| BlockList* work_list() { return _work_list; } |
| |
| void iterate_all(); |
| void iterate_one(BlockBegin* block); |
| |
| ValueSet* state() { return _set; } |
| void set_state_from (ValueSet* state) { _set->set_from(state); } |
| ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } |
| void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } |
| // Returns true if caused a change in the block's state. |
| bool merge_state_for(BlockBegin* block, |
| ValueSet* incoming_state); |
| |
| public: |
| // constructor |
| NullCheckEliminator(Optimizer* opt) |
| : _opt(opt) |
| , _set(new ValueSet()) |
| , _last_explicit_null_check(NULL) |
| , _block_states(BlockBegin::number_of_blocks(), NULL) |
| , _work_list(new BlockList()) { |
| _visitable_instructions = new ValueSet(); |
| _visitor.set_eliminator(this); |
| } |
| |
| Optimizer* opt() { return _opt; } |
| IR* ir () { return opt()->ir(); } |
| |
| // Process a graph |
| void iterate(BlockBegin* root); |
| |
| // In some situations (like NullCheck(x); getfield(x)) the debug |
| // information from the explicit NullCheck can be used to populate |
| // the getfield, even if the two instructions are in different |
| // scopes; this allows implicit null checks to be used but the |
| // correct exception information to be generated. We must clear the |
| // last-traversed NullCheck when we reach a potentially-exception- |
| // throwing instruction, as well as in some other cases. |
| void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } |
| NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } |
| Value last_explicit_null_check_obj() { return (_last_explicit_null_check |
| ? _last_explicit_null_check->obj() |
| : NULL); } |
| NullCheck* consume_last_explicit_null_check() { |
| _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); |
| _last_explicit_null_check->set_can_trap(false); |
| return _last_explicit_null_check; |
| } |
| void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } |
| |
| // Handlers for relevant instructions |
| // (separated out from NullCheckVisitor for clarity) |
| |
| // The basic contract is that these must leave the instruction in |
| // the desired state; must not assume anything about the state of |
| // the instruction. We make multiple passes over some basic blocks |
| // and the last pass is the only one whose result is valid. |
| void handle_AccessField (AccessField* x); |
| void handle_ArrayLength (ArrayLength* x); |
| void handle_LoadIndexed (LoadIndexed* x); |
| void handle_StoreIndexed (StoreIndexed* x); |
| void handle_NullCheck (NullCheck* x); |
| void handle_Invoke (Invoke* x); |
| void handle_NewInstance (NewInstance* x); |
| void handle_NewArray (NewArray* x); |
| void handle_AccessMonitor (AccessMonitor* x); |
| void handle_Intrinsic (Intrinsic* x); |
| void handle_ExceptionObject (ExceptionObject* x); |
| void handle_Phi (Phi* x); |
| }; |
| |
| |
| // NEEDS_CLEANUP |
| // There may be other instructions which need to clear the last |
| // explicit null check. Anything across which we can not hoist the |
| // debug information for a NullCheck instruction must clear it. It |
| // might be safer to pattern match "NullCheck ; {AccessField, |
| // ArrayLength, LoadIndexed}" but it is more easily structured this way. |
| // Should test to see performance hit of clearing it for all handlers |
| // with empty bodies below. If it is negligible then we should leave |
| // that in for safety, otherwise should think more about it. |
| void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } |
| void NullCheckVisitor::do_Local (Local* x) {} |
| void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } |
| void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } |
| void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } |
| void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } |
| void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } |
| void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } |
| void NullCheckVisitor::do_NegateOp (NegateOp* x) {} |
| void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } |
| void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} |
| void NullCheckVisitor::do_LogicOp (LogicOp* x) {} |
| void NullCheckVisitor::do_CompareOp (CompareOp* x) {} |
| void NullCheckVisitor::do_IfOp (IfOp* x) {} |
| void NullCheckVisitor::do_Convert (Convert* x) {} |
| void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } |
| void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } |
| void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } |
| void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } |
| void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } |
| void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } |
| void NullCheckVisitor::do_CheckCast (CheckCast* x) {} |
| void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} |
| void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } |
| void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } |
| void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->clear_last_explicit_null_check(); } |
| void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} |
| void NullCheckVisitor::do_Goto (Goto* x) {} |
| void NullCheckVisitor::do_If (If* x) {} |
| void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} |
| void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} |
| void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} |
| void NullCheckVisitor::do_Return (Return* x) {} |
| void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } |
| void NullCheckVisitor::do_Base (Base* x) {} |
| void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} |
| void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } |
| void NullCheckVisitor::do_RoundFP (RoundFP* x) {} |
| void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} |
| void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} |
| void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} |
| void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} |
| void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} |
| void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} |
| void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } |
| void NullCheckVisitor::do_ProfileCounter (ProfileCounter* x) {} |
| |
| |
| NullCheckEliminator* NullCheckEliminator::_static_nce = NULL; |
| |
| |
| void NullCheckEliminator::do_value(Value* p) { |
| assert(*p != NULL, "should not find NULL instructions"); |
| if (_static_nce->visitable(*p)) { |
| _static_nce->mark_visited(*p); |
| (*p)->visit(&_static_nce->_visitor); |
| } |
| } |
| |
| bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { |
| ValueSet* state = state_for(block); |
| if (state == NULL) { |
| state = incoming_state->copy(); |
| set_state_for(block, state); |
| return true; |
| } else { |
| bool changed = state->set_intersect(incoming_state); |
| if (PrintNullCheckElimination && changed) { |
| tty->print_cr("Block %d's null check state changed", block->block_id()); |
| } |
| return changed; |
| } |
| } |
| |
| |
| void NullCheckEliminator::iterate_all() { |
| while (work_list()->length() > 0) { |
| iterate_one(work_list()->pop()); |
| } |
| } |
| |
| |
| void NullCheckEliminator::iterate_one(BlockBegin* block) { |
| _static_nce = this; |
| clear_visitable_state(); |
| // clear out an old explicit null checks |
| set_last_explicit_null_check(NULL); |
| |
| if (PrintNullCheckElimination) { |
| tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", |
| block->block_id(), |
| ir()->method()->holder()->name()->as_utf8(), |
| ir()->method()->name()->as_utf8(), |
| ir()->method()->signature()->as_symbol()->as_utf8()); |
| } |
| |
| // Create new state if none present (only happens at root) |
| if (state_for(block) == NULL) { |
| ValueSet* tmp_state = new ValueSet(); |
| set_state_for(block, tmp_state); |
| // Initial state is that local 0 (receiver) is non-null for |
| // non-static methods |
| ValueStack* stack = block->state(); |
| IRScope* scope = stack->scope(); |
| ciMethod* method = scope->method(); |
| if (!method->is_static()) { |
| Local* local0 = stack->local_at(0)->as_Local(); |
| assert(local0 != NULL, "must be"); |
| assert(local0->type() == objectType, "invalid type of receiver"); |
| |
| if (local0 != NULL) { |
| // Local 0 is used in this scope |
| tmp_state->put(local0); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); |
| } |
| } |
| } |
| } |
| |
| // Must copy block's state to avoid mutating it during iteration |
| // through the block -- otherwise "not-null" states can accidentally |
| // propagate "up" through the block during processing of backward |
| // branches and algorithm is incorrect (and does not converge) |
| set_state_from(state_for(block)); |
| |
| // allow visiting of Phis belonging to this block |
| for_each_phi_fun(block, phi, |
| mark_visitable(phi); |
| ); |
| |
| BlockEnd* e = block->end(); |
| assert(e != NULL, "incomplete graph"); |
| int i; |
| |
| // Propagate the state before this block into the exception |
| // handlers. They aren't true successors since we aren't guaranteed |
| // to execute the whole block before executing them. Also putting |
| // them on first seems to help reduce the amount of iteration to |
| // reach a fixed point. |
| for (i = 0; i < block->number_of_exception_handlers(); i++) { |
| BlockBegin* next = block->exception_handler_at(i); |
| if (merge_state_for(next, state())) { |
| if (!work_list()->contains(next)) { |
| work_list()->push(next); |
| } |
| } |
| } |
| |
| // Iterate through block, updating state. |
| for (Instruction* instr = block; instr != NULL; instr = instr->next()) { |
| // Mark instructions in this block as visitable as they are seen |
| // in the instruction list. This keeps the iteration from |
| // visiting instructions which are references in other blocks or |
| // visiting instructions more than once. |
| mark_visitable(instr); |
| if (instr->is_root() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { |
| mark_visited(instr); |
| instr->input_values_do(&NullCheckEliminator::do_value); |
| instr->visit(&_visitor); |
| } |
| } |
| |
| // Propagate state to successors if necessary |
| for (i = 0; i < e->number_of_sux(); i++) { |
| BlockBegin* next = e->sux_at(i); |
| if (merge_state_for(next, state())) { |
| if (!work_list()->contains(next)) { |
| work_list()->push(next); |
| } |
| } |
| } |
| } |
| |
| |
| void NullCheckEliminator::iterate(BlockBegin* block) { |
| work_list()->push(block); |
| iterate_all(); |
| } |
| |
| void NullCheckEliminator::handle_AccessField(AccessField* x) { |
| if (x->is_static()) { |
| if (x->as_LoadField() != NULL) { |
| // If the field is a non-null static final object field (as is |
| // often the case for sun.misc.Unsafe), put this LoadField into |
| // the non-null map |
| ciField* field = x->field(); |
| if (field->is_constant()) { |
| ciConstant field_val = field->constant_value(); |
| BasicType field_type = field_val.basic_type(); |
| if (field_type == T_OBJECT || field_type == T_ARRAY) { |
| ciObject* obj_val = field_val.as_object(); |
| if (!obj_val->is_null_object()) { |
| if (PrintNullCheckElimination) { |
| tty->print_cr("AccessField %d proven non-null by static final non-null oop check", |
| x->id()); |
| } |
| set_put(x); |
| } |
| } |
| } |
| } |
| // Be conservative |
| clear_last_explicit_null_check(); |
| return; |
| } |
| |
| Value obj = x->obj(); |
| if (set_contains(obj)) { |
| // Value is non-null => update AccessField |
| if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { |
| x->set_explicit_null_check(consume_last_explicit_null_check()); |
| x->set_needs_null_check(true); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", |
| x->explicit_null_check()->id(), x->id(), obj->id()); |
| } |
| } else { |
| x->set_explicit_null_check(NULL); |
| x->set_needs_null_check(false); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); |
| } |
| } |
| } else { |
| set_put(obj); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| x->set_explicit_null_check(NULL); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { |
| Value array = x->array(); |
| if (set_contains(array)) { |
| // Value is non-null => update AccessArray |
| if (last_explicit_null_check_obj() == array) { |
| x->set_explicit_null_check(consume_last_explicit_null_check()); |
| x->set_needs_null_check(true); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", |
| x->explicit_null_check()->id(), x->id(), array->id()); |
| } |
| } else { |
| x->set_explicit_null_check(NULL); |
| x->set_needs_null_check(false); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); |
| } |
| } |
| } else { |
| set_put(array); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| x->set_explicit_null_check(NULL); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { |
| Value array = x->array(); |
| if (set_contains(array)) { |
| // Value is non-null => update AccessArray |
| if (last_explicit_null_check_obj() == array) { |
| x->set_explicit_null_check(consume_last_explicit_null_check()); |
| x->set_needs_null_check(true); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", |
| x->explicit_null_check()->id(), x->id(), array->id()); |
| } |
| } else { |
| x->set_explicit_null_check(NULL); |
| x->set_needs_null_check(false); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); |
| } |
| } |
| } else { |
| set_put(array); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| x->set_explicit_null_check(NULL); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { |
| Value array = x->array(); |
| if (set_contains(array)) { |
| // Value is non-null => update AccessArray |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); |
| } |
| x->set_needs_null_check(false); |
| } else { |
| set_put(array); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_NullCheck(NullCheck* x) { |
| Value obj = x->obj(); |
| if (set_contains(obj)) { |
| // Already proven to be non-null => this NullCheck is useless |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); |
| } |
| // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. |
| // The code generator won't emit LIR for a NullCheck that cannot trap. |
| x->set_can_trap(false); |
| } else { |
| // May be null => add to map and set last explicit NullCheck |
| x->set_can_trap(true); |
| // make sure it's pinned if it can trap |
| x->pin(Instruction::PinExplicitNullCheck); |
| set_put(obj); |
| set_last_explicit_null_check(x); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); |
| } |
| } |
| } |
| |
| |
| void NullCheckEliminator::handle_Invoke(Invoke* x) { |
| if (!x->has_receiver()) { |
| // Be conservative |
| clear_last_explicit_null_check(); |
| return; |
| } |
| |
| Value recv = x->receiver(); |
| if (!set_contains(recv)) { |
| set_put(recv); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); |
| } |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_NewInstance(NewInstance* x) { |
| set_put(x); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("NewInstance %d is non-null", x->id()); |
| } |
| } |
| |
| |
| void NullCheckEliminator::handle_NewArray(NewArray* x) { |
| set_put(x); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("NewArray %d is non-null", x->id()); |
| } |
| } |
| |
| |
| void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { |
| set_put(x); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("ExceptionObject %d is non-null", x->id()); |
| } |
| } |
| |
| |
| void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { |
| Value obj = x->obj(); |
| if (set_contains(obj)) { |
| // Value is non-null => update AccessMonitor |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); |
| } |
| x->set_needs_null_check(false); |
| } else { |
| set_put(obj); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { |
| if (!x->has_receiver()) { |
| // Be conservative |
| clear_last_explicit_null_check(); |
| return; |
| } |
| |
| Value recv = x->receiver(); |
| if (set_contains(recv)) { |
| // Value is non-null => update Intrinsic |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); |
| } |
| x->set_needs_null_check(false); |
| } else { |
| set_put(recv); |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); |
| } |
| // Ensure previous passes do not cause wrong state |
| x->set_needs_null_check(true); |
| } |
| clear_last_explicit_null_check(); |
| } |
| |
| |
| void NullCheckEliminator::handle_Phi(Phi* x) { |
| int i; |
| bool all_non_null = true; |
| if (x->is_illegal()) { |
| all_non_null = false; |
| } else { |
| for (i = 0; i < x->operand_count(); i++) { |
| Value input = x->operand_at(i); |
| if (!set_contains(input)) { |
| all_non_null = false; |
| } |
| } |
| } |
| |
| if (all_non_null) { |
| // Value is non-null => update Phi |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); |
| } |
| x->set_needs_null_check(false); |
| } else if (set_contains(x)) { |
| set_remove(x); |
| } |
| } |
| |
| |
| void Optimizer::eliminate_null_checks() { |
| ResourceMark rm; |
| |
| NullCheckEliminator nce(this); |
| |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Starting null check elimination for method %s::%s%s", |
| ir()->method()->holder()->name()->as_utf8(), |
| ir()->method()->name()->as_utf8(), |
| ir()->method()->signature()->as_symbol()->as_utf8()); |
| } |
| |
| // Apply to graph |
| nce.iterate(ir()->start()); |
| |
| // walk over the graph looking for exception |
| // handlers and iterate over them as well |
| int nblocks = BlockBegin::number_of_blocks(); |
| BlockList blocks(nblocks); |
| boolArray visited_block(nblocks, false); |
| |
| blocks.push(ir()->start()); |
| visited_block[ir()->start()->block_id()] = true; |
| for (int i = 0; i < blocks.length(); i++) { |
| BlockBegin* b = blocks[i]; |
| // exception handlers need to be treated as additional roots |
| for (int e = b->number_of_exception_handlers(); e-- > 0; ) { |
| BlockBegin* excp = b->exception_handler_at(e); |
| int id = excp->block_id(); |
| if (!visited_block[id]) { |
| blocks.push(excp); |
| visited_block[id] = true; |
| nce.iterate(excp); |
| } |
| } |
| // traverse successors |
| BlockEnd *end = b->end(); |
| for (int s = end->number_of_sux(); s-- > 0; ) { |
| BlockBegin* next = end->sux_at(s); |
| int id = next->block_id(); |
| if (!visited_block[id]) { |
| blocks.push(next); |
| visited_block[id] = true; |
| } |
| } |
| } |
| |
| |
| if (PrintNullCheckElimination) { |
| tty->print_cr("Done with null check elimination for method %s::%s%s", |
| ir()->method()->holder()->name()->as_utf8(), |
| ir()->method()->name()->as_utf8(), |
| ir()->method()->signature()->as_symbol()->as_utf8()); |
| } |
| } |
