1 /*
   2  * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "memory/allocation.inline.hpp"
  27 #include "opto/addnode.hpp"
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/machnode.hpp"
  30 #include "opto/matcher.hpp"
  31 #include "opto/mathexactnode.hpp"
  32 #include "opto/subnode.hpp"
  33 
  34 template <typename OverflowOp>
  35 class AddHelper {
  36 public:
  37   typedef typename OverflowOp::TypeClass TypeClass;
  38   typedef typename TypeClass::NativeType NativeType;
  39 
  40   static bool will_overflow(NativeType value1, NativeType value2) {
  41     NativeType result = value1 + value2;
  42     // Hacker's Delight 2-12 Overflow if both arguments have the opposite sign of the result
  43     if (((value1 ^ result) & (value2 ^ result)) >= 0) {
  44       return false;
  45     }
  46     return true;
  47   }
  48 
  49   static bool can_overflow(const Type* type1, const Type* type2) {
  50     if (type1 == TypeClass::ZERO || type2 == TypeClass::ZERO) {
  51       return false;
  52     }
  53     return true;
  54   }
  55 };
  56 
  57 template <typename OverflowOp>
  58 class SubHelper {
  59 public:
  60   typedef typename OverflowOp::TypeClass TypeClass;
  61   typedef typename TypeClass::NativeType NativeType;
  62 
  63   static bool will_overflow(NativeType value1, NativeType value2) {
  64     NativeType result = value1 - value2;
  65     // hacker's delight 2-12 overflow iff the arguments have different signs and
  66     // the sign of the result is different than the sign of arg1
  67     if (((value1 ^ value2) & (value1 ^ result)) >= 0) {
  68       return false;
  69     }
  70     return true;
  71   }
  72 
  73   static bool can_overflow(const Type* type1, const Type* type2) {
  74     if (type2 == TypeClass::ZERO) {
  75       return false;
  76     }
  77     return true;
  78   }
  79 };
  80 
  81 template <typename OverflowOp>
  82 class MulHelper {
  83 public:
  84   typedef typename OverflowOp::TypeClass TypeClass;
  85 
  86   static bool can_overflow(const Type* type1, const Type* type2) {
  87     if (type1 == TypeClass::ZERO || type2 == TypeClass::ZERO) {
  88       return false;
  89     } else if (type1 == TypeClass::ONE || type2 == TypeClass::ONE) {
  90       return false;
  91     }
  92     return true;
  93   }
  94 };
  95 
  96 bool OverflowAddINode::will_overflow(jint v1, jint v2) const {
  97   return AddHelper<OverflowAddINode>::will_overflow(v1, v2);
  98 }
  99 
 100 bool OverflowSubINode::will_overflow(jint v1, jint v2) const {
 101   return SubHelper<OverflowSubINode>::will_overflow(v1, v2);
 102 }
 103 
 104 bool OverflowMulINode::will_overflow(jint v1, jint v2) const {
 105     jlong result = (jlong) v1 * (jlong) v2;
 106     if ((jint) result == result) {
 107       return false;
 108     }
 109     return true;
 110 }
 111 
 112 bool OverflowAddLNode::will_overflow(jlong v1, jlong v2) const {
 113   return AddHelper<OverflowAddLNode>::will_overflow(v1, v2);
 114 }
 115 
 116 bool OverflowSubLNode::will_overflow(jlong v1, jlong v2) const {
 117   return SubHelper<OverflowSubLNode>::will_overflow(v1, v2);
 118 }
 119 
 120 bool OverflowMulLNode::will_overflow(jlong val1, jlong val2) const {
 121     jlong result = val1 * val2;
 122     jlong ax = (val1 < 0 ? -val1 : val1);
 123     jlong ay = (val2 < 0 ? -val2 : val2);
 124 
 125     bool overflow = false;
 126     if ((ax | ay) & CONST64(0xFFFFFFFF00000000)) {
 127       // potential overflow if any bit in upper 32 bits are set
 128       if ((val1 == min_jlong && val2 == -1) || (val2 == min_jlong && val1 == -1)) {
 129         // -1 * Long.MIN_VALUE will overflow
 130         overflow = true;
 131       } else if (val2 != 0 && (result / val2 != val1)) {
 132         overflow = true;
 133       }
 134     }
 135 
 136     return overflow;
 137 }
 138 
 139 bool OverflowAddINode::can_overflow(const Type* t1, const Type* t2) const {
 140   return AddHelper<OverflowAddINode>::can_overflow(t1, t2);
 141 }
 142 
 143 bool OverflowSubINode::can_overflow(const Type* t1, const Type* t2) const {
 144   if (in(1) == in(2)) {
 145     return false;
 146   }
 147   return SubHelper<OverflowSubINode>::can_overflow(t1, t2);
 148 }
 149 
 150 bool OverflowMulINode::can_overflow(const Type* t1, const Type* t2) const {
 151   return MulHelper<OverflowMulINode>::can_overflow(t1, t2);
 152 }
 153 
 154 bool OverflowAddLNode::can_overflow(const Type* t1, const Type* t2) const {
 155   return AddHelper<OverflowAddLNode>::can_overflow(t1, t2);
 156 }
 157 
 158 bool OverflowSubLNode::can_overflow(const Type* t1, const Type* t2) const {
 159   if (in(1) == in(2)) {
 160     return false;
 161   }
 162   return SubHelper<OverflowSubLNode>::can_overflow(t1, t2);
 163 }
 164 
 165 bool OverflowMulLNode::can_overflow(const Type* t1, const Type* t2) const {
 166   return MulHelper<OverflowMulLNode>::can_overflow(t1, t2);
 167 }
 168 
 169 const Type* OverflowNode::sub(const Type* t1, const Type* t2) const {
 170   fatal("sub() should not be called for '%s'", NodeClassNames[this->Opcode()]);
 171   return TypeInt::CC;
 172 }
 173 
 174 template <typename OverflowOp>
 175 struct IdealHelper {
 176   typedef typename OverflowOp::TypeClass TypeClass; // TypeInt, TypeLong
 177   typedef typename TypeClass::NativeType NativeType;
 178 
 179   static Node* Ideal(const OverflowOp* node, PhaseGVN* phase, bool can_reshape) {
 180     Node* arg1 = node->in(1);
 181     Node* arg2 = node->in(2);
 182     const Type* type1 = phase->type(arg1);
 183     const Type* type2 = phase->type(arg2);
 184 
 185     if (type1 == NULL || type2 == NULL) {
 186       return NULL;
 187     }
 188 
 189     if (type1 != Type::TOP && type1->singleton() &&
 190         type2 != Type::TOP && type2->singleton()) {
 191       NativeType val1 = TypeClass::as_self(type1)->get_con();
 192       NativeType val2 = TypeClass::as_self(type2)->get_con();
 193       if (node->will_overflow(val1, val2) == false) {
 194         Node* con_result = ConINode::make(0);
 195         return con_result;
 196       }
 197       return NULL;
 198     }
 199     return NULL;
 200   }
 201 
 202   static const Type* Value(const OverflowOp* node, PhaseTransform* phase) {
 203     const Type *t1 = phase->type( node->in(1) );
 204     const Type *t2 = phase->type( node->in(2) );
 205     if( t1 == Type::TOP ) return Type::TOP;
 206     if( t2 == Type::TOP ) return Type::TOP;
 207 
 208     const TypeClass* i1 = TypeClass::as_self(t1);
 209     const TypeClass* i2 = TypeClass::as_self(t2);
 210 
 211     if (i1 == NULL || i2 == NULL) {
 212       return TypeInt::CC;
 213     }
 214 
 215     if (t1->singleton() && t2->singleton()) {
 216       NativeType val1 = i1->get_con();
 217       NativeType val2 = i2->get_con();
 218       if (node->will_overflow(val1, val2)) {
 219         return TypeInt::CC;
 220       }
 221       return TypeInt::ZERO;
 222     } else if (i1 != TypeClass::TYPE_DOMAIN && i2 != TypeClass::TYPE_DOMAIN) {
 223       if (node->will_overflow(i1->_lo, i2->_lo)) {
 224         return TypeInt::CC;
 225       } else if (node->will_overflow(i1->_lo, i2->_hi)) {
 226         return TypeInt::CC;
 227       } else if (node->will_overflow(i1->_hi, i2->_lo)) {
 228         return TypeInt::CC;
 229       } else if (node->will_overflow(i1->_hi, i2->_hi)) {
 230         return TypeInt::CC;
 231       }
 232       return TypeInt::ZERO;
 233     }
 234 
 235     if (!node->can_overflow(t1, t2)) {
 236       return TypeInt::ZERO;
 237     }
 238     return TypeInt::CC;
 239   }
 240 };
 241 
 242 Node* OverflowINode::Ideal(PhaseGVN* phase, bool can_reshape) {
 243   return IdealHelper<OverflowINode>::Ideal(this, phase, can_reshape);
 244 }
 245 
 246 Node* OverflowLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
 247   return IdealHelper<OverflowLNode>::Ideal(this, phase, can_reshape);
 248 }
 249 
 250 const Type* OverflowINode::Value(PhaseGVN* phase) const {
 251   return IdealHelper<OverflowINode>::Value(this, phase);
 252 }
 253 
 254 const Type* OverflowLNode::Value(PhaseGVN* phase) const {
 255   return IdealHelper<OverflowLNode>::Value(this, phase);
 256 }
 257 
--- EOF ---