jdk8-mips64-public/hotspot: src/share/vm/c1/c1_Optimizer.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_Optimizer.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_Optimizer.cpp

Wed, 31 Aug 2011 16:46:11 -0700

author: never
date: Wed, 31 Aug 2011 16:46:11 -0700
changeset 3099: c124e2e7463e
parent 2989: 15559220ce79
child 3386: 7bca37d28f32
permissions: -rw-r--r--

7083786: dead various dead chunks of code
Reviewed-by: iveresov, kvn

 /*
  * Copyright (c) 1999, 2011, 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_Canonicalizer.hpp"
 #include "c1/c1_Optimizer.hpp"
 #include "c1/c1_ValueMap.hpp"
 #include "c1/c1_ValueSet.hpp"
 #include "c1/c1_ValueStack.hpp"
 #include "utilities/bitMap.inline.hpp"
 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 _ifop_count;                               // the number of IfOps successfully simplified
   int _has_substitution;
  public:
   CE_Eliminator(IR* hir) : _cee_count(0), _ifop_count(0), _hir(hir) {
     _has_substitution = false;
     _hir->iterate_preorder(this);
     if (_has_substitution) {
       // substituted some ifops/phis, so resolve the substitution
       SubstitutionResolver sr(_hir);
     }
   }
   int cee_count() const                          { return _cee_count; }
   int ifop_count() const                         { return _ifop_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);
  private:
   Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval);
 };
 void CE_Eliminator::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);
   // 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());
     NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci()));
     cur_end = cur_end->set_next(t_value);
   }
   if (f_value == f_const) {
     f_value = new Constant(f_const->type());
     NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci()));
     cur_end = cur_end->set_next(f_value);
   }
   Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value);
   assert(result != NULL, "make_ifop must return a non-null instruction");
   if (!result->is_linked() && result->can_be_linked()) {
     NOT_PRODUCT(result->set_printable_bci(if_->printable_bci()));
     cur_end = cur_end->set_next(result);
   }
   // 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->caller_state();
     assert(goto_state != NULL, "states do not match up");
   }
   goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci());
   goto_state->push(result->type(), result);
   assert(goto_state->is_same(sux_state), "states must match now");
   goto_->set_state(goto_state);
   cur_end = cur_end->set_next(goto_, goto_state->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());
     tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id());
   }
   _hir->verify();
 }
 Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) {
   if (!OptimizeIfOps) {
     return new IfOp(x, cond, y, tval, fval);
   }
   tval = tval->subst();
   fval = fval->subst();
   if (tval == fval) {
     _ifop_count++;
     return tval;
   }
   x = x->subst();
   y = y->subst();
   Constant* y_const = y->as_Constant();
   if (y_const != NULL) {
     IfOp* x_ifop = x->as_IfOp();
     if (x_ifop != NULL) {                 // x is an ifop, y is a constant
       Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant();
       Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant();
       if (x_tval_const != NULL && x_fval_const != NULL) {
         Instruction::Condition x_ifop_cond = x_ifop->cond();
         Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const);
         Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const);
         // not_comparable here is a valid return in case we're comparing unloaded oop constants
         if (t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable) {
           Value new_tval = t_compare_res == Constant::cond_true ? tval : fval;
           Value new_fval = f_compare_res == Constant::cond_true ? tval : fval;
           _ifop_count++;
           if (new_tval == new_fval) {
             return new_tval;
           } else {
             return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval);
           }
         }
       }
     } else {
       Constant* x_const = x->as_Constant();
       if (x_const != NULL) {         // x and y are constants
         Constant::CompareResult x_compare_res = x_const->compare(cond, y_const);
         // not_comparable here is a valid return in case we're comparing unloaded oop constants
         if (x_compare_res != Constant::not_comparable) {
           _ifop_count++;
           return x_compare_res == Constant::cond_true ? tval : fval;
         }
       }
     }
   }
   return new IfOp(x, cond, y, tval, fval);
 }
 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();
         assert(end_state->scope() == sux_state->scope(), "scopes must match");
         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);
         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);
                 }
                 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");
                   NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci()));
                   prev->set_next(newif);
                   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_ProfileInvoke  (ProfileInvoke*   x);
   void do_RuntimeCall    (RuntimeCall*     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: public ValueVisitor {
  private:
   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);
   void visit(Value* f);
   // 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) { nce()->clear_last_explicit_null_check(); }
 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()->handle_Intrinsic(x);     }
 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_ProfileInvoke  (ProfileInvoke*   x) {}
 void NullCheckVisitor::do_RuntimeCall    (RuntimeCall*     x) {}
 void NullCheckEliminator::visit(Value* p) {
   assert(*p != NULL, "should not find NULL instructions");
   if (visitable(*p)) {
     mark_visited(*p);
     (*p)->visit(&_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) {
   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_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) {
       mark_visited(instr);
       instr->input_values_do(this);
       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()) {
     if (x->id() == vmIntrinsics::_arraycopy) {
       for (int i = 0; i < x->number_of_arguments(); i++) {
         x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i)));
       }
     }
     // 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());
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/c1/c1_Optimizer.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_Optimizer.cpp