Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: mathexactnode.cpp Sprache: C

/*
* Copyright (c) 2013, 2018, 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 "memory/allocation.inline.hpp"
#include "opto/addnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/machnode.hpp"
#include "opto/matcher.hpp"
#include "opto/mathexactnode.hpp"
#include "opto/subnode.hpp"

template <typename OverflowOp>
class AddHelper {
public:
  typedef typename OverflowOp::TypeClass TypeClass;
  typedef typename TypeClass::NativeType NativeType;

  static bool will_overflow(NativeType value1, NativeType value2) {
    NativeType result = value1 + value2;
    // Hacker's Delight 2-12 Overflow if both arguments have the opposite sign of the result
    if (((value1 ^ result) & (value2 ^ result)) >= 0) {
      return false;
    }
    return true;
  }

  static bool can_overflow(const Type* type1, const Type* type2) {
    if (type1 == TypeClass::ZERO || type2 == TypeClass::ZERO) {
      return false;
    }
    return true;
  }
};

template <typename OverflowOp>
class SubHelper {
public:
  typedef typename OverflowOp::TypeClass TypeClass;
  typedef typename TypeClass::NativeType NativeType;

  static bool will_overflow(NativeType value1, NativeType value2) {
    NativeType result = value1 - value2;
    // hacker's delight 2-12 overflow iff the arguments have different signs and
    // the sign of the result is different than the sign of arg1
    if (((value1 ^ value2) & (value1 ^ result)) >= 0) {
      return false;
    }
    return true;
  }

  static bool can_overflow(const Type* type1, const Type* type2) {
    if (type2 == TypeClass::ZERO) {
      return false;
    }
    return true;
  }
};

template <typename OverflowOp>
class MulHelper {
public:
  typedef typename OverflowOp::TypeClass TypeClass;

  static bool can_overflow(const Type* type1, const Type* type2) {
    if (type1 == TypeClass::ZERO || type2 == TypeClass::ZERO) {
      return false;
    } else if (type1 == TypeClass::ONE || type2 == TypeClass::ONE) {
      return false;
    }
    return true;
  }
};

bool OverflowAddINode::will_overflow(jint v1, jint v2) const {
  return AddHelper<OverflowAddINode>::will_overflow(v1, v2);
}

bool OverflowSubINode::will_overflow(jint v1, jint v2) const {
  return SubHelper<OverflowSubINode>::will_overflow(v1, v2);
}

bool OverflowMulINode::will_overflow(jint v1, jint v2) const {
    jlong result = (jlong) v1 * (jlong) v2;
    if ((jint) result == result) {
      return false;
    }
    return true;
}

bool OverflowAddLNode::will_overflow(jlong v1, jlong v2) const {
  return AddHelper<OverflowAddLNode>::will_overflow(v1, v2);
}

bool OverflowSubLNode::will_overflow(jlong v1, jlong v2) const {
  return SubHelper<OverflowSubLNode>::will_overflow(v1, v2);
}

bool OverflowMulLNode::is_overflow(jlong val1, jlong val2) {
    // x * { 0, 1 } will never overflow. Even for x = min_jlong
    if (val1 == 0 || val2 == 0 || val1 == 1 || val2 == 1) {
      return false;
    }

    // x * min_jlong for x not in { 0, 1 } overflows
    // even -1 as -1 * min_jlong is an overflow
    if (val1 == min_jlong || val2 == min_jlong) {
      return true;
    }

    // if (x * y) / y == x there is no overflow
    //
    // the multiplication here is done as unsigned to avoid undefined behaviour which
    // can be used by the compiler to assume that the check further down (result / val2 != val1)
    // is always false and breaks the overflow check
    julong v1 = (julong) val1;
    julong v2 = (julong) val2;
    julong tmp = v1 * v2;
    jlong result = (jlong) tmp;

    if (result / val2 != val1) {
      return true;
    }

    return false;
}

bool OverflowAddINode::can_overflow(const Type* t1, const Type* t2) const {
  return AddHelper<OverflowAddINode>::can_overflow(t1, t2);
}

bool OverflowSubINode::can_overflow(const Type* t1, const Type* t2) const {
  if (in(1) == in(2)) {
    return false;
  }
  return SubHelper<OverflowSubINode>::can_overflow(t1, t2);
}

bool OverflowMulINode::can_overflow(const Type* t1, const Type* t2) const {
  return MulHelper<OverflowMulINode>::can_overflow(t1, t2);
}

bool OverflowAddLNode::can_overflow(const Type* t1, const Type* t2) const {
  return AddHelper<OverflowAddLNode>::can_overflow(t1, t2);
}

bool OverflowSubLNode::can_overflow(const Type* t1, const Type* t2) const {
  if (in(1) == in(2)) {
    return false;
  }
  return SubHelper<OverflowSubLNode>::can_overflow(t1, t2);
}

bool OverflowMulLNode::can_overflow(const Type* t1, const Type* t2) const {
  return MulHelper<OverflowMulLNode>::can_overflow(t1, t2);
}

const Type* OverflowNode::sub(const Type* t1, const Type* t2) const {
  fatal("sub() should not be called for '%s'", NodeClassNames[this->Opcode()]);
  return TypeInt::CC;
}

template <typename OverflowOp>
struct IdealHelper {
  typedef typename OverflowOp::TypeClass TypeClass; // TypeInt, TypeLong
  typedef typename TypeClass::NativeType NativeType;

  static Node* Ideal(const OverflowOp* node, PhaseGVN* phase, bool can_reshape) {
    Node* arg1 = node->in(1);
    Node* arg2 = node->in(2);
    const Type* type1 = phase->type(arg1);
    const Type* type2 = phase->type(arg2);

    if (type1 == NULL || type2 == NULL) {
      return NULL;
    }

    if (type1 != Type::TOP && type1->singleton() &&
        type2 != Type::TOP && type2->singleton()) {
      NativeType val1 = TypeClass::as_self(type1)->get_con();
      NativeType val2 = TypeClass::as_self(type2)->get_con();
      if (node->will_overflow(val1, val2) == false) {
        Node* con_result = ConINode::make(0);
        return con_result;
      }
      return NULL;
    }
    return NULL;
  }

  static const Type* Value(const OverflowOp* node, PhaseTransform* phase) {
    const Type *t1 = phase->type( node->in(1) );
    const Type *t2 = phase->type( node->in(2) );
    if( t1 == Type::TOP ) return Type::TOP;
    if( t2 == Type::TOP ) return Type::TOP;

    const TypeClass* i1 = TypeClass::as_self(t1);
    const TypeClass* i2 = TypeClass::as_self(t2);

    if (i1 == NULL || i2 == NULL) {
      return TypeInt::CC;
    }

    if (t1->singleton() && t2->singleton()) {
      NativeType val1 = i1->get_con();
      NativeType val2 = i2->get_con();
      if (node->will_overflow(val1, val2)) {
        return TypeInt::CC;
      }
      return TypeInt::ZERO;
    } else if (i1 != TypeClass::TYPE_DOMAIN && i2 != TypeClass::TYPE_DOMAIN) {
      if (node->will_overflow(i1->_lo, i2->_lo)) {
        return TypeInt::CC;
      } else if (node->will_overflow(i1->_lo, i2->_hi)) {
        return TypeInt::CC;
      } else if (node->will_overflow(i1->_hi, i2->_lo)) {
        return TypeInt::CC;
      } else if (node->will_overflow(i1->_hi, i2->_hi)) {
        return TypeInt::CC;
      }
      return TypeInt::ZERO;
    }

    if (!node->can_overflow(t1, t2)) {
      return TypeInt::ZERO;
    }
    return TypeInt::CC;
  }
};

Node* OverflowINode::Ideal(PhaseGVN* phase, bool can_reshape) {
  return IdealHelper<OverflowINode>::Ideal(this, phase, can_reshape);
}

Node* OverflowLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
  return IdealHelper<OverflowLNode>::Ideal(this, phase, can_reshape);
}

const Type* OverflowINode::Value(PhaseGVN* phase) const {
  return IdealHelper<OverflowINode>::Value(this, phase);
}

const Type* OverflowLNode::Value(PhaseGVN* phase) const {
  return IdealHelper<OverflowLNode>::Value(this, phase);
}

¤ Dauer der Verarbeitung: 0.33 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.