text: /*
   * Copyright (c) 1999, 2013, 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_InstructionPrinter.hpp"
  #include "c1/c1_ValueStack.hpp"
  #include "ci/ciArray.hpp"
  #include "runtime/sharedRuntime.hpp"
  
  
  class PrintValueVisitor: public ValueVisitor {
    void visit(Value* vp) {
      (*vp)->print_line();
    }
  };
  
  void Canonicalizer::set_canonical(Value x) {
    assert(x != NULL, "value must exist");
    // Note: we can not currently substitute root nodes which show up in
    // the instruction stream (because the instruction list is embedded
    // in the instructions).
    if (canonical() != x) {
  #ifndef PRODUCT
      if (!x->has_printable_bci()) {
        x->set_printable_bci(bci());
      }
  #endif
      if (PrintCanonicalization) {
        PrintValueVisitor do_print_value;
        canonical()->input_values_do(&do_print_value);
        canonical()->print_line();
        tty->print_cr("canonicalized to:");
        x->input_values_do(&do_print_value);
        x->print_line();
        tty->cr();
      }
      assert(_canonical->type()->tag() == x->type()->tag(), "types must match");
      _canonical = x;
    }
  }
  
  
  void Canonicalizer::move_const_to_right(Op2* x) {
    if (x->x()->type()->is_constant() && x->is_commutative()) x->swap_operands();
  }
  
  
  void Canonicalizer::do_Op2(Op2* x) {
    if (x->x() == x->y()) {
      switch (x->op()) {
      case Bytecodes::_isub: set_constant(0); return;
      case Bytecodes::_lsub: set_constant(jlong_cast(0)); return;
      case Bytecodes::_iand: // fall through
      case Bytecodes::_land: // fall through
      case Bytecodes::_ior:  // fall through
      case Bytecodes::_lor : set_canonical(x->x()); return;
      case Bytecodes::_ixor: set_constant(0); return;
      case Bytecodes::_lxor: set_constant(jlong_cast(0)); return;
      }
    }
  
    if (x->x()->type()->is_constant() && x->y()->type()->is_constant()) {
      // do constant folding for selected operations
      switch (x->type()->tag()) {
        case intTag:
          { jint a = x->x()->type()->as_IntConstant()->value();
            jint b = x->y()->type()->as_IntConstant()->value();
            switch (x->op()) {
              case Bytecodes::_iadd: set_constant(a + b); return;
              case Bytecodes::_isub: set_constant(a - b); return;
              case Bytecodes::_imul: set_constant(a * b); return;
              case Bytecodes::_idiv:
                if (b != 0) {
                  if (a == min_jint && b == -1) {
                    set_constant(min_jint);
                  } else {
                    set_constant(a / b);
                  }
                  return;
                }
                break;
              case Bytecodes::_irem:
                if (b != 0) {
                  if (a == min_jint && b == -1) {
                    set_constant(0);
                  } else {
                    set_constant(a % b);
                  }
                  return;
                }
                break;
              case Bytecodes::_iand: set_constant(a & b); return;
              case Bytecodes::_ior : set_constant(a | b); return;
              case Bytecodes::_ixor: set_constant(a ^ b); return;
            }
          }
          break;
        case longTag:
          { jlong a = x->x()->type()->as_LongConstant()->value();
            jlong b = x->y()->type()->as_LongConstant()->value();
            switch (x->op()) {
              case Bytecodes::_ladd: set_constant(a + b); return;
              case Bytecodes::_lsub: set_constant(a - b); return;
              case Bytecodes::_lmul: set_constant(a * b); return;
              case Bytecodes::_ldiv:
                if (b != 0) {
                  set_constant(SharedRuntime::ldiv(b, a));
                  return;
                }
                break;
              case Bytecodes::_lrem:
                if (b != 0) {
                  set_constant(SharedRuntime::lrem(b, a));
                  return;
                }
                break;
              case Bytecodes::_land: set_constant(a & b); return;
              case Bytecodes::_lor : set_constant(a | b); return;
              case Bytecodes::_lxor: set_constant(a ^ b); return;
            }
          }
          break;
        // other cases not implemented (must be extremely careful with floats & doubles!)
      }
    }
    // make sure constant is on the right side, if any
    move_const_to_right(x);
  
    if (x->y()->type()->is_constant()) {
      // do constant folding for selected operations
      switch (x->type()->tag()) {
        case intTag:
          if (x->y()->type()->as_IntConstant()->value() == 0) {
            switch (x->op()) {
              case Bytecodes::_iadd: set_canonical(x->x()); return;
              case Bytecodes::_isub: set_canonical(x->x()); return;
              case Bytecodes::_imul: set_constant(0); return;
                // Note: for div and rem, make sure that C semantics
                //       corresponds to Java semantics!
              case Bytecodes::_iand: set_constant(0); return;
              case Bytecodes::_ior : set_canonical(x->x()); return;
            }
          }
          break;
        case longTag:
          if (x->y()->type()->as_LongConstant()->value() == (jlong)0) {
            switch (x->op()) {
              case Bytecodes::_ladd: set_canonical(x->x()); return;
              case Bytecodes::_lsub: set_canonical(x->x()); return;
              case Bytecodes::_lmul: set_constant((jlong)0); return;
                // Note: for div and rem, make sure that C semantics
                //       corresponds to Java semantics!
              case Bytecodes::_land: set_constant((jlong)0); return;
              case Bytecodes::_lor : set_canonical(x->x()); return;
            }
          }
          break;
      }
    }
  }
  
  
  void Canonicalizer::do_Phi            (Phi*             x) {}
  void Canonicalizer::do_Constant       (Constant*        x) {}
  void Canonicalizer::do_Local          (Local*           x) {}
  void Canonicalizer::do_LoadField      (LoadField*       x) {}
  
  // checks if v is in the block that is currently processed by
  // GraphBuilder. This is the only block that has not BlockEnd yet.
  static bool in_current_block(Value v) {
    int max_distance = 4;
    while (max_distance > 0 && v != NULL && v->as_BlockEnd() == NULL) {
      v = v->next();
      max_distance--;
    }
    return v == NULL;
  }
  
  void Canonicalizer::do_StoreField     (StoreField*      x) {
    // If a value is going to be stored into a field or array some of
    // the conversions emitted by javac are unneeded because the fields
    // are packed to their natural size.
    Convert* conv = x->value()->as_Convert();
    if (conv) {
      Value value = NULL;
      BasicType type = x->field()->type()->basic_type();
      switch (conv->op()) {
      case Bytecodes::_i2b: if (type == T_BYTE)  value = conv->value(); break;
      case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) value = conv->value(); break;
      case Bytecodes::_i2c: if (type == T_CHAR  || type == T_BYTE)  value = conv->value(); break;
      }
      // limit this optimization to current block
      if (value != NULL && in_current_block(conv)) {
        set_canonical(new StoreField(x->obj(), x->offset(), x->field(), value, x->is_static(),
                                     x->state_before(), x->needs_patching()));
        return;
      }
    }
  
  }
  
  void Canonicalizer::do_ArrayLength    (ArrayLength*     x) {
    NewArray* array = x->array()->as_NewArray();
    if (array != NULL && array->length() != NULL) {
      Constant* length = array->length()->as_Constant();
      if (length != NULL) {
        // do not use the Constant itself, but create a new Constant
        // with same value Otherwise a Constant is live over multiple
        // blocks without being registered in a state array.
        assert(length->type()->as_IntConstant() != NULL, "array length must be integer");
        set_constant(length->type()->as_IntConstant()->value());
      }
    } else {
      LoadField* lf = x->array()->as_LoadField();
      if (lf != NULL) {
        ciField* field = lf->field();
        if (field->is_constant() && field->is_static()) {
          // final static field
          ciObject* c = field->constant_value().as_object();
          if (c->is_array()) {
            ciArray* array = (ciArray*) c;
            set_constant(array->length());
          }
        }
      }
    }
  }
  
  void Canonicalizer::do_LoadIndexed    (LoadIndexed*     x) {}
  void Canonicalizer::do_StoreIndexed   (StoreIndexed*    x) {
    // If a value is going to be stored into a field or array some of
    // the conversions emitted by javac are unneeded because the fields
    // are packed to their natural size.
    Convert* conv = x->value()->as_Convert();
    if (conv) {
      Value value = NULL;
      BasicType type = x->elt_type();
      switch (conv->op()) {
      case Bytecodes::_i2b: if (type == T_BYTE)  value = conv->value(); break;
      case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) value = conv->value(); break;
      case Bytecodes::_i2c: if (type == T_CHAR  || type == T_BYTE) value = conv->value(); break;
      }
      // limit this optimization to current block
      if (value != NULL && in_current_block(conv)) {
        set_canonical(new StoreIndexed(x->array(), x->index(), x->length(),
                                       x->elt_type(), value, x->state_before()));
        return;
      }
    }
  
  
  }
  
  
  void Canonicalizer::do_NegateOp(NegateOp* x) {
    ValueType* t = x->x()->type();
    if (t->is_constant()) {
      switch (t->tag()) {
        case intTag   : set_constant(-t->as_IntConstant   ()->value()); return;
        case longTag  : set_constant(-t->as_LongConstant  ()->value()); return;
        case floatTag : set_constant(-t->as_FloatConstant ()->value()); return;
        case doubleTag: set_constant(-t->as_DoubleConstant()->value()); return;
        default       : ShouldNotReachHere();
      }
    }
  }
  
  
  void Canonicalizer::do_ArithmeticOp   (ArithmeticOp*    x) { do_Op2(x); }
  
  
  void Canonicalizer::do_ShiftOp        (ShiftOp*         x) {
    ValueType* t = x->x()->type();
    ValueType* t2 = x->y()->type();
    if (t->is_constant()) {
      switch (t->tag()) {
      case intTag   : if (t->as_IntConstant()->value() == 0)         { set_constant(0); return; } break;
      case longTag  : if (t->as_LongConstant()->value() == (jlong)0) { set_constant(jlong_cast(0)); return; } break;
      default       : ShouldNotReachHere();
      }
      if (t2->is_constant()) {
        if (t->tag() == intTag) {
          int value = t->as_IntConstant()->value();
          int shift = t2->as_IntConstant()->value() & 31;
          jint mask = ~(~0 << (32 - shift));
          if (shift == 0) mask = ~0;
          switch (x->op()) {
            case Bytecodes::_ishl:  set_constant(value << shift); return;
            case Bytecodes::_ishr:  set_constant(value >> shift); return;
            case Bytecodes::_iushr: set_constant((value >> shift) & mask); return;
          }
        } else if (t->tag() == longTag) {
          jlong value = t->as_LongConstant()->value();
          int shift = t2->as_IntConstant()->value() & 63;
          jlong mask = ~(~jlong_cast(0) << (64 - shift));
          if (shift == 0) mask = ~jlong_cast(0);
          switch (x->op()) {
            case Bytecodes::_lshl:  set_constant(value << shift); return;
            case Bytecodes::_lshr:  set_constant(value >> shift); return;
            case Bytecodes::_lushr: set_constant((value >> shift) & mask); return;
          }
        }
      }
    }
    if (t2->is_constant()) {
      switch (t2->tag()) {
        case intTag   : if (t2->as_IntConstant()->value() == 0)  set_canonical(x->x()); return;
        case longTag  : if (t2->as_IntConstant()->value() == 0)  set_canonical(x->x()); return;
        default       : ShouldNotReachHere();
      }
    }
  }
  
  
  void Canonicalizer::do_LogicOp        (LogicOp*         x) { do_Op2(x); }
  void Canonicalizer::do_CompareOp      (CompareOp*       x) {
    if (x->x() == x->y()) {
      switch (x->x()->type()->tag()) {
        case longTag: set_constant(0); break;
        case floatTag: {
          FloatConstant* fc = x->x()->type()->as_FloatConstant();
          if (fc) {
            if (g_isnan(fc->value())) {
              set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
            } else {
              set_constant(0);
            }
          }
          break;
        }
        case doubleTag: {
          DoubleConstant* dc = x->x()->type()->as_DoubleConstant();
          if (dc) {
            if (g_isnan(dc->value())) {
              set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
            } else {
              set_constant(0);
            }
          }
          break;
        }
      }
    } else if (x->x()->type()->is_constant() && x->y()->type()->is_constant()) {
      switch (x->x()->type()->tag()) {
        case longTag: {
          jlong vx = x->x()->type()->as_LongConstant()->value();
          jlong vy = x->y()->type()->as_LongConstant()->value();
          if (vx == vy)
            set_constant(0);
          else if (vx < vy)
            set_constant(-1);
          else
            set_constant(1);
          break;
        }
  
        case floatTag: {
          float vx = x->x()->type()->as_FloatConstant()->value();
          float vy = x->y()->type()->as_FloatConstant()->value();
          if (g_isnan(vx) || g_isnan(vy))
            set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
          else if (vx == vy)
            set_constant(0);
          else if (vx < vy)
            set_constant(-1);
          else
            set_constant(1);
          break;
        }
  
        case doubleTag: {
          double vx = x->x()->type()->as_DoubleConstant()->value();
          double vy = x->y()->type()->as_DoubleConstant()->value();
          if (g_isnan(vx) || g_isnan(vy))
            set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
          else if (vx == vy)
            set_constant(0);
          else if (vx < vy)
            set_constant(-1);
          else
            set_constant(1);
          break;
        }
      }
  
    }
  }
  
  
  void Canonicalizer::do_IfInstanceOf(IfInstanceOf*    x) {}
  
  void Canonicalizer::do_IfOp(IfOp* x) {
    // Caution: do not use do_Op2(x) here for now since
    //          we map the condition to the op for now!
    move_const_to_right(x);
  }
  
  
  void Canonicalizer::do_Intrinsic      (Intrinsic*       x) {
    switch (x->id()) {
    case vmIntrinsics::_floatToRawIntBits   : {
      FloatConstant* c = x->argument_at(0)->type()->as_FloatConstant();
      if (c != NULL) {
        JavaValue v;
        v.set_jfloat(c->value());
        set_constant(v.get_jint());
      }
      break;
    }
    case vmIntrinsics::_intBitsToFloat      : {
      IntConstant* c = x->argument_at(0)->type()->as_IntConstant();
      if (c != NULL) {
        JavaValue v;
        v.set_jint(c->value());
        set_constant(v.get_jfloat());
      }
      break;
    }
    case vmIntrinsics::_doubleToRawLongBits : {
      DoubleConstant* c = x->argument_at(0)->type()->as_DoubleConstant();
      if (c != NULL) {
        JavaValue v;
        v.set_jdouble(c->value());
        set_constant(v.get_jlong());
      }
      break;
    }
    case vmIntrinsics::_longBitsToDouble    : {
      LongConstant* c = x->argument_at(0)->type()->as_LongConstant();
      if (c != NULL) {
        JavaValue v;
        v.set_jlong(c->value());
        set_constant(v.get_jdouble());
      }
      break;
    }
    case vmIntrinsics::_isInstance          : {
      assert(x->number_of_arguments() == 2, "wrong type");
  
      InstanceConstant* c = x->argument_at(0)->type()->as_InstanceConstant();
      if (c != NULL && !c->value()->is_null_object()) {
        // ciInstance::java_mirror_type() returns non-NULL only for Java mirrors
        ciType* t = c->value()->as_instance()->java_mirror_type();
        if (t->is_klass()) {
          // substitute cls.isInstance(obj) of a constant Class into
          // an InstantOf instruction
          InstanceOf* i = new InstanceOf(t->as_klass(), x->argument_at(1), x->state_before());
          set_canonical(i);
          // and try to canonicalize even further
          do_InstanceOf(i);
        } else {
          assert(t->is_primitive_type(), "should be a primitive type");
          // cls.isInstance(obj) always returns false for primitive classes
          set_constant(0);
        }
      }
      break;
    }
    }
  }
  
  void Canonicalizer::do_Convert        (Convert*         x) {
    if (x->value()->type()->is_constant()) {
      switch (x->op()) {
      case Bytecodes::_i2b:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 24) >> 24)); break;
      case Bytecodes::_i2s:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 16) >> 16)); break;
      case Bytecodes::_i2c:  set_constant((int)(x->value()->type()->as_IntConstant()->value() & ((1<<16)-1))); break;
      case Bytecodes::_i2l:  set_constant((jlong)(x->value()->type()->as_IntConstant()->value()));             break;
      case Bytecodes::_i2f:  set_constant((float)(x->value()->type()->as_IntConstant()->value()));             break;
      case Bytecodes::_i2d:  set_constant((double)(x->value()->type()->as_IntConstant()->value()));            break;
      case Bytecodes::_l2i:  set_constant((int)(x->value()->type()->as_LongConstant()->value()));              break;
      case Bytecodes::_l2f:  set_constant(SharedRuntime::l2f(x->value()->type()->as_LongConstant()->value())); break;
      case Bytecodes::_l2d:  set_constant(SharedRuntime::l2d(x->value()->type()->as_LongConstant()->value())); break;
      case Bytecodes::_f2d:  set_constant((double)(x->value()->type()->as_FloatConstant()->value()));          break;
      case Bytecodes::_f2i:  set_constant(SharedRuntime::f2i(x->value()->type()->as_FloatConstant()->value())); break;
      case Bytecodes::_f2l:  set_constant(SharedRuntime::f2l(x->value()->type()->as_FloatConstant()->value())); break;
      case Bytecodes::_d2f:  set_constant((float)(x->value()->type()->as_DoubleConstant()->value()));          break;
      case Bytecodes::_d2i:  set_constant(SharedRuntime::d2i(x->value()->type()->as_DoubleConstant()->value())); break;
      case Bytecodes::_d2l:  set_constant(SharedRuntime::d2l(x->value()->type()->as_DoubleConstant()->value())); break;
      default:
        ShouldNotReachHere();
      }
    }
  
    Value value = x->value();
    BasicType type = T_ILLEGAL;
    LoadField* lf = value->as_LoadField();
    if (lf) {
      type = lf->field_type();
    } else {
      LoadIndexed* li = value->as_LoadIndexed();
      if (li) {
        type = li->elt_type();
      } else {
        Convert* conv = value->as_Convert();
        if (conv) {
          switch (conv->op()) {
            case Bytecodes::_i2b: type = T_BYTE;  break;
            case Bytecodes::_i2s: type = T_SHORT; break;
            case Bytecodes::_i2c: type = T_CHAR;  break;
          }
        }
      }
    }
    if (type != T_ILLEGAL) {
      switch (x->op()) {
        case Bytecodes::_i2b: if (type == T_BYTE)                    set_canonical(x->value()); break;
        case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) set_canonical(x->value()); break;
        case Bytecodes::_i2c: if (type == T_CHAR)                    set_canonical(x->value()); break;
      }
    } else {
      Op2* op2 = x->value()->as_Op2();
      if (op2 && op2->op() == Bytecodes::_iand && op2->y()->type()->is_constant()) {
        jint safebits = 0;
        jint mask = op2->y()->type()->as_IntConstant()->value();
        switch (x->op()) {
          case Bytecodes::_i2b: safebits = 0x7f;   break;
          case Bytecodes::_i2s: safebits = 0x7fff; break;
          case Bytecodes::_i2c: safebits = 0xffff; break;
        }
        // When casting a masked integer to a smaller signed type, if
        // the mask doesn't include the sign bit the cast isn't needed.
        if (safebits && (mask & ~safebits) == 0) {
          set_canonical(x->value());
        }
      }
    }
  
  }
  
  void Canonicalizer::do_NullCheck      (NullCheck*       x) {
    if (x->obj()->as_NewArray() != NULL || x->obj()->as_NewInstance() != NULL) {
      set_canonical(x->obj());
    } else {
      Constant* con = x->obj()->as_Constant();
      if (con) {
        ObjectType* c = con->type()->as_ObjectType();
        if (c && c->is_loaded()) {
          ObjectConstant* oc = c->as_ObjectConstant();
          if (!oc || !oc->value()->is_null_object()) {
            set_canonical(con);
          }
        }
      }
    }
  }
  
  void Canonicalizer::do_TypeCast       (TypeCast*        x) {}
  void Canonicalizer::do_Invoke         (Invoke*          x) {}
  void Canonicalizer::do_NewInstance    (NewInstance*     x) {}
  void Canonicalizer::do_NewTypeArray   (NewTypeArray*    x) {}
  void Canonicalizer::do_NewObjectArray (NewObjectArray*  x) {}
  void Canonicalizer::do_NewMultiArray  (NewMultiArray*   x) {}
  void Canonicalizer::do_CheckCast      (CheckCast*       x) {
    if (x->klass()->is_loaded()) {
      Value obj = x->obj();
      ciType* klass = obj->exact_type();
      if (klass == NULL) klass = obj->declared_type();
      if (klass != NULL && klass->is_loaded() && klass->is_subtype_of(x->klass())) {
        set_canonical(obj);
        return;
      }
      // checkcast of null returns null
      if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
        set_canonical(obj);
      }
    }
  }
  void Canonicalizer::do_InstanceOf     (InstanceOf*      x) {
    if (x->klass()->is_loaded()) {
      Value obj = x->obj();
      ciType* exact = obj->exact_type();
      if (exact != NULL && exact->is_loaded() && (obj->as_NewInstance() || obj->as_NewArray())) {
        set_constant(exact->is_subtype_of(x->klass()) ? 1 : 0);
        return;
      }
      // instanceof null returns false
      if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
        set_constant(0);
      }
    }
  
  }
  void Canonicalizer::do_MonitorEnter   (MonitorEnter*    x) {}
  void Canonicalizer::do_MonitorExit    (MonitorExit*     x) {}
  void Canonicalizer::do_BlockBegin     (BlockBegin*      x) {}
  void Canonicalizer::do_Goto           (Goto*            x) {}
  
  
  static bool is_true(jlong x, If::Condition cond, jlong y) {
    switch (cond) {
      case If::eql: return x == y;
      case If::neq: return x != y;
      case If::lss: return x <  y;
      case If::leq: return x <= y;
      case If::gtr: return x >  y;
      case If::geq: return x >= y;
    }
    ShouldNotReachHere();
    return false;
  }
  
  static bool is_safepoint(BlockEnd* x, BlockBegin* sux) {
    // An Instruction with multiple successors, x, is replaced by a Goto
    // to a single successor, sux. Is a safepoint check needed = was the
    // instruction being replaced a safepoint and the single remaining
    // successor a back branch?
    return x->is_safepoint() && (sux->bci() < x->state_before()->bci());
  }
  
  void Canonicalizer::do_If(If* x) {
    // move const to right
    if (x->x()->type()->is_constant()) x->swap_operands();
    // simplify
    const Value l = x->x(); ValueType* lt = l->type();
    const Value r = x->y(); ValueType* rt = r->type();
  
    if (l == r && !lt->is_float_kind()) {
      // pattern: If (a cond a) => simplify to Goto
      BlockBegin* sux;
      switch (x->cond()) {
      case If::eql: sux = x->sux_for(true);  break;
      case If::neq: sux = x->sux_for(false); break;
      case If::lss: sux = x->sux_for(false); break;
      case If::leq: sux = x->sux_for(true);  break;
      case If::gtr: sux = x->sux_for(false); break;
      case If::geq: sux = x->sux_for(true);  break;
      }
      // If is a safepoint then the debug information should come from the state_before of the If.
      set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
      return;
    }
  
    if (lt->is_constant() && rt->is_constant()) {
      if (x->x()->as_Constant() != NULL) {
        // pattern: If (lc cond rc) => simplify to: Goto
        BlockBegin* sux = x->x()->as_Constant()->compare(x->cond(), x->y(),
                                                         x->sux_for(true),
                                                         x->sux_for(false));
        if (sux != NULL) {
          // If is a safepoint then the debug information should come from the state_before of the If.
          set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
        }
      }
    } else if (rt->as_IntConstant() != NULL) {
      // pattern: If (l cond rc) => investigate further
      const jint rc = rt->as_IntConstant()->value();
      if (l->as_CompareOp() != NULL) {
        // pattern: If ((a cmp b) cond rc) => simplify to: If (x cond y) or: Goto
        CompareOp* cmp = l->as_CompareOp();
        bool unordered_is_less = cmp->op() == Bytecodes::_fcmpl || cmp->op() == Bytecodes::_dcmpl;
        BlockBegin* lss_sux = x->sux_for(is_true(-1, x->cond(), rc)); // successor for a < b
        BlockBegin* eql_sux = x->sux_for(is_true( 0, x->cond(), rc)); // successor for a = b
        BlockBegin* gtr_sux = x->sux_for(is_true(+1, x->cond(), rc)); // successor for a > b
        BlockBegin* nan_sux = unordered_is_less ? lss_sux : gtr_sux ; // successor for unordered
        // Note: At this point all successors (lss_sux, eql_sux, gtr_sux, nan_sux) are
        //       equal to x->tsux() or x->fsux(). Furthermore, nan_sux equals either
        //       lss_sux or gtr_sux.
        if (lss_sux == eql_sux && eql_sux == gtr_sux) {
          // all successors identical => simplify to: Goto
          set_canonical(new Goto(lss_sux, x->state_before(), x->is_safepoint()));
        } else {
          // two successors differ and two successors are the same => simplify to: If (x cmp y)
          // determine new condition & successors
          If::Condition cond;
          BlockBegin* tsux = NULL;
          BlockBegin* fsux = NULL;
               if (lss_sux == eql_sux) { cond = If::leq; tsux = lss_sux; fsux = gtr_sux; }
          else if (lss_sux == gtr_sux) { cond = If::neq; tsux = lss_sux; fsux = eql_sux; }
          else if (eql_sux == gtr_sux) { cond = If::geq; tsux = eql_sux; fsux = lss_sux; }
          else                         { ShouldNotReachHere();                           }
          If* canon = new If(cmp->x(), cond, nan_sux == tsux, cmp->y(), tsux, fsux, cmp->state_before(), x->is_safepoint());
          if (cmp->x() == cmp->y()) {
            do_If(canon);
          } else {
            if (compilation()->profile_branches()) {
              // TODO: If profiling, leave floating point comparisons unoptimized.
              // We currently do not support profiling of the unordered case.
              switch(cmp->op()) {
                case Bytecodes::_fcmpl: case Bytecodes::_fcmpg:
                case Bytecodes::_dcmpl: case Bytecodes::_dcmpg:
                  set_canonical(x);
                  return;
              }
            }
            set_bci(cmp->state_before()->bci());
            set_canonical(canon);
          }
        }
      } else if (l->as_InstanceOf() != NULL) {
        // NOTE: Code permanently disabled for now since it leaves the old InstanceOf
        //       instruction in the graph (it is pinned). Need to fix this at some point.
        //       It should also be left in the graph when generating a profiled method version or Goto
        //       has to know that it was an InstanceOf.
        return;
        // pattern: If ((obj instanceof klass) cond rc) => simplify to: IfInstanceOf or: Goto
        InstanceOf* inst = l->as_InstanceOf();
        BlockBegin* is_inst_sux = x->sux_for(is_true(1, x->cond(), rc)); // successor for instanceof == 1
        BlockBegin* no_inst_sux = x->sux_for(is_true(0, x->cond(), rc)); // successor for instanceof == 0
        if (is_inst_sux == no_inst_sux && inst->is_loaded()) {
          // both successors identical and klass is loaded => simplify to: Goto
          set_canonical(new Goto(is_inst_sux, x->state_before(), x->is_safepoint()));
        } else {
          // successors differ => simplify to: IfInstanceOf
          set_canonical(new IfInstanceOf(inst->klass(), inst->obj(), true, inst->state_before()->bci(), is_inst_sux, no_inst_sux));
        }
      }
    } else if (rt == objectNull && (l->as_NewInstance() || l->as_NewArray())) {
      if (x->cond() == Instruction::eql) {
        BlockBegin* sux = x->fsux();
        set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
      } else {
        assert(x->cond() == Instruction::neq, "only other valid case");
        BlockBegin* sux = x->tsux();
        set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
      }
    }
  }
  
  
  void Canonicalizer::do_TableSwitch(TableSwitch* x) {
    if (x->tag()->type()->is_constant()) {
      int v = x->tag()->type()->as_IntConstant()->value();
      BlockBegin* sux = x->default_sux();
      if (v >= x->lo_key() && v <= x->hi_key()) {
        sux = x->sux_at(v - x->lo_key());
      }
      set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
    } else if (x->number_of_sux() == 1) {
      // NOTE: Code permanently disabled for now since the switch statement's
      //       tag expression may produce side-effects in which case it must
      //       be executed.
      return;
      // simplify to Goto
      set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
    } else if (x->number_of_sux() == 2) {
      // NOTE: Code permanently disabled for now since it produces two new nodes
      //       (Constant & If) and the Canonicalizer cannot return them correctly
      //       yet. For now we copied the corresponding code directly into the
      //       GraphBuilder (i.e., we should never reach here).
      return;
      // simplify to If
      assert(x->lo_key() == x->hi_key(), "keys must be the same");
      Constant* key = new Constant(new IntConstant(x->lo_key()));
      set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
    }
  }
  
  
  void Canonicalizer::do_LookupSwitch(LookupSwitch* x) {
    if (x->tag()->type()->is_constant()) {
      int v = x->tag()->type()->as_IntConstant()->value();
      BlockBegin* sux = x->default_sux();
      for (int i = 0; i < x->length(); i++) {
        if (v == x->key_at(i)) {
          sux = x->sux_at(i);
        }
      }
      set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
    } else if (x->number_of_sux() == 1) {
      // NOTE: Code permanently disabled for now since the switch statement's
      //       tag expression may produce side-effects in which case it must
      //       be executed.
      return;
      // simplify to Goto
      set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
    } else if (x->number_of_sux() == 2) {
      // NOTE: Code permanently disabled for now since it produces two new nodes
      //       (Constant & If) and the Canonicalizer cannot return them correctly
      //       yet. For now we copied the corresponding code directly into the
      //       GraphBuilder (i.e., we should never reach here).
      return;
      // simplify to If
      assert(x->length() == 1, "length must be the same");
      Constant* key = new Constant(new IntConstant(x->key_at(0)));
      set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
    }
  }
  
  
  void Canonicalizer::do_Return         (Return*          x) {}
  void Canonicalizer::do_Throw          (Throw*           x) {}
  void Canonicalizer::do_Base           (Base*            x) {}
  void Canonicalizer::do_OsrEntry       (OsrEntry*        x) {}
  void Canonicalizer::do_ExceptionObject(ExceptionObject* x) {}
  
  static bool match_index_and_scale(Instruction*  instr,
                                    Instruction** index,
                                    int*          log2_scale,
                                    Instruction** instr_to_unpin) {
    *instr_to_unpin = NULL;
  
    // Skip conversion ops
    Convert* convert = instr->as_Convert();
    if (convert != NULL) {
      instr = convert->value();
    }
  
    ShiftOp* shift = instr->as_ShiftOp();
    if (shift != NULL) {
      if (shift->is_pinned()) {
        *instr_to_unpin = shift;
      }
      // Constant shift value?
      Constant* con = shift->y()->as_Constant();
      if (con == NULL) return false;
      // Well-known type and value?
      IntConstant* val = con->type()->as_IntConstant();
      if (val == NULL) return false;
      if (shift->x()->type() != intType) return false;
      *index = shift->x();
      int tmp_scale = val->value();
      if (tmp_scale >= 0 && tmp_scale < 4) {
        *log2_scale = tmp_scale;
        return true;
      } else {
        return false;
      }
    }
  
    ArithmeticOp* arith = instr->as_ArithmeticOp();
    if (arith != NULL) {
      if (arith->is_pinned()) {
        *instr_to_unpin = arith;
      }
      // Check for integer multiply
      if (arith->op() == Bytecodes::_imul) {
        // See if either arg is a known constant
        Constant* con = arith->x()->as_Constant();
        if (con != NULL) {
          *index = arith->y();
        } else {
          con = arith->y()->as_Constant();
          if (con == NULL) return false;
          *index = arith->x();
        }
        if ((*index)->type() != intType) return false;
        // Well-known type and value?
        IntConstant* val = con->type()->as_IntConstant();
        if (val == NULL) return false;
        switch (val->value()) {
        case 1: *log2_scale = 0; return true;
        case 2: *log2_scale = 1; return true;
        case 4: *log2_scale = 2; return true;
        case 8: *log2_scale = 3; return true;
        default:            return false;
        }
      }
    }
  
    // Unknown instruction sequence; don't touch it
    return false;
  }
  
  
  static bool match(UnsafeRawOp* x,
                    Instruction** base,
                    Instruction** index,
                    int*          log2_scale) {
    Instruction* instr_to_unpin = NULL;
    ArithmeticOp* root = x->base()->as_ArithmeticOp();
    if (root == NULL) return false;
    // Limit ourselves to addition for now
    if (root->op() != Bytecodes::_ladd) return false;
    // Try to find shift or scale op
    if (match_index_and_scale(root->y(), index, log2_scale, &instr_to_unpin)) {
      *base = root->x();
    } else if (match_index_and_scale(root->x(), index, log2_scale, &instr_to_unpin)) {
      *base = root->y();
    } else if (root->y()->as_Convert() != NULL) {
      Convert* convert = root->y()->as_Convert();
      if (convert->op() == Bytecodes::_i2l && convert->value()->type() == intType) {
        // pick base and index, setting scale at 1
        *base  = root->x();
        *index = convert->value();
        *log2_scale = 0;
      } else {
        return false;
      }
    } else {
      // doesn't match any expected sequences
      return false;
    }
  
    // If the value is pinned then it will be always be computed so
    // there's no profit to reshaping the expression.
    return !root->is_pinned();
  }
  
  
  void Canonicalizer::do_UnsafeRawOp(UnsafeRawOp* x) {
    Instruction* base = NULL;
    Instruction* index = NULL;
    int          log2_scale;
  
    if (match(x, &base, &index, &log2_scale)) {
      x->set_base(base);
      x->set_index(index);
      x->set_log2_scale(log2_scale);
      if (PrintUnsafeOptimization) {
        tty->print_cr("Canonicalizer: UnsafeRawOp id %d: base = id %d, index = id %d, log2_scale = %d",
                      x->id(), x->base()->id(), x->index()->id(), x->log2_scale());
      }
    }
  }
  
  void Canonicalizer::do_RoundFP(RoundFP* x) {}
  void Canonicalizer::do_UnsafeGetRaw(UnsafeGetRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
  void Canonicalizer::do_UnsafePutRaw(UnsafePutRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
  void Canonicalizer::do_UnsafeGetObject(UnsafeGetObject* x) {}
  void Canonicalizer::do_UnsafePutObject(UnsafePutObject* x) {}
  void Canonicalizer::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {}
  void Canonicalizer::do_UnsafePrefetchRead (UnsafePrefetchRead*  x) {}
  void Canonicalizer::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {}
  void Canonicalizer::do_ProfileCall(ProfileCall* x) {}
  void Canonicalizer::do_ProfileReturnType(ProfileReturnType* x) {}
  void Canonicalizer::do_ProfileInvoke(ProfileInvoke* x) {}
  void Canonicalizer::do_RuntimeCall(RuntimeCall* x) {}
  void Canonicalizer::do_RangeCheckPredicate(RangeCheckPredicate* x) {}
  #ifdef ASSERT
  void Canonicalizer::do_Assert(Assert* x) {}
  #endif
  void Canonicalizer::do_MemBar(MemBar* x) {}
  