1 /*
   2  * Copyright (c) 1997, 2012, 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/connode.hpp"
  29 #include "opto/memnode.hpp"
  30 #include "opto/mulnode.hpp"
  31 #include "opto/phaseX.hpp"
  32 #include "opto/subnode.hpp"
  33 
  34 // Portions of code courtesy of Clifford Click
  35 
  36 
  37 //=============================================================================
  38 //------------------------------hash-------------------------------------------
  39 // Hash function over MulNodes.  Needs to be commutative; i.e., I swap
  40 // (commute) inputs to MulNodes willy-nilly so the hash function must return
  41 // the same value in the presence of edge swapping.
  42 uint MulNode::hash() const {
  43   return (uintptr_t)in(1) + (uintptr_t)in(2) + Opcode();
  44 }
  45 
  46 //------------------------------Identity---------------------------------------
  47 // Multiplying a one preserves the other argument
  48 Node *MulNode::Identity( PhaseTransform *phase ) {
  49   register const Type *one = mul_id();  // The multiplicative identity
  50   if( phase->type( in(1) )->higher_equal( one ) ) return in(2);
  51   if( phase->type( in(2) )->higher_equal( one ) ) return in(1);
  52 
  53   return this;
  54 }
  55 
  56 //------------------------------Ideal------------------------------------------
  57 // We also canonicalize the Node, moving constants to the right input,
  58 // and flatten expressions (so that 1+x+2 becomes x+3).
  59 Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
  60   const Type *t1 = phase->type( in(1) );
  61   const Type *t2 = phase->type( in(2) );
  62   Node *progress = NULL;        // Progress flag
  63   // We are OK if right is a constant, or right is a load and
  64   // left is a non-constant.
  65   if( !(t2->singleton() ||
  66         (in(2)->is_Load() && !(t1->singleton() || in(1)->is_Load())) ) ) {
  67     if( t1->singleton() ||       // Left input is a constant?
  68         // Otherwise, sort inputs (commutativity) to help value numbering.
  69         (in(1)->_idx > in(2)->_idx) ) {
  70       swap_edges(1, 2);
  71       const Type *t = t1;
  72       t1 = t2;
  73       t2 = t;
  74       progress = this;            // Made progress
  75     }
  76   }
  77 
  78   // If the right input is a constant, and the left input is a product of a
  79   // constant, flatten the expression tree.
  80   uint op = Opcode();
  81   if( t2->singleton() &&        // Right input is a constant?
  82       op != Op_MulF &&          // Float & double cannot reassociate
  83       op != Op_MulD ) {
  84     if( t2 == Type::TOP ) return NULL;
  85     Node *mul1 = in(1);
  86 #ifdef ASSERT
  87     // Check for dead loop
  88     int   op1 = mul1->Opcode();
  89     if( phase->eqv( mul1, this ) || phase->eqv( in(2), this ) ||
  90         ( op1 == mul_opcode() || op1 == add_opcode() ) &&
  91         ( phase->eqv( mul1->in(1), this ) || phase->eqv( mul1->in(2), this ) ||
  92           phase->eqv( mul1->in(1), mul1 ) || phase->eqv( mul1->in(2), mul1 ) ) )
  93       assert(false, "dead loop in MulNode::Ideal");
  94 #endif
  95 
  96     if( mul1->Opcode() == mul_opcode() ) {  // Left input is a multiply?
  97       // Mul of a constant?
  98       const Type *t12 = phase->type( mul1->in(2) );
  99       if( t12->singleton() && t12 != Type::TOP) { // Left input is an add of a constant?
 100         // Compute new constant; check for overflow
 101         const Type *tcon01 = ((MulNode*)mul1)->mul_ring(t2,t12);
 102         if( tcon01->singleton() ) {
 103           // The Mul of the flattened expression
 104           set_req(1, mul1->in(1));
 105           set_req(2, phase->makecon( tcon01 ));
 106           t2 = tcon01;
 107           progress = this;      // Made progress
 108         }
 109       }
 110     }
 111     // If the right input is a constant, and the left input is an add of a
 112     // constant, flatten the tree: (X+con1)*con0 ==> X*con0 + con1*con0
 113     const Node *add1 = in(1);
 114     if( add1->Opcode() == add_opcode() ) {      // Left input is an add?
 115       // Add of a constant?
 116       const Type *t12 = phase->type( add1->in(2) );
 117       if( t12->singleton() && t12 != Type::TOP ) { // Left input is an add of a constant?
 118         assert( add1->in(1) != add1, "dead loop in MulNode::Ideal" );
 119         // Compute new constant; check for overflow
 120         const Type *tcon01 = mul_ring(t2,t12);
 121         if( tcon01->singleton() ) {
 122 
 123         // Convert (X+con1)*con0 into X*con0
 124           Node *mul = clone();    // mul = ()*con0
 125           mul->set_req(1,add1->in(1));  // mul = X*con0
 126           mul = phase->transform(mul);
 127 
 128           Node *add2 = add1->clone();
 129           add2->set_req(1, mul);        // X*con0 + con0*con1
 130           add2->set_req(2, phase->makecon(tcon01) );
 131           progress = add2;
 132         }
 133       }
 134     } // End of is left input an add
 135   } // End of is right input a Mul
 136 
 137   return progress;
 138 }
 139 
 140 //------------------------------Value-----------------------------------------
 141 const Type *MulNode::Value( PhaseTransform *phase ) const {
 142   const Type *t1 = phase->type( in(1) );
 143   const Type *t2 = phase->type( in(2) );
 144   // Either input is TOP ==> the result is TOP
 145   if( t1 == Type::TOP ) return Type::TOP;
 146   if( t2 == Type::TOP ) return Type::TOP;
 147 
 148   // Either input is ZERO ==> the result is ZERO.
 149   // Not valid for floats or doubles since +0.0 * -0.0 --> +0.0
 150   int op = Opcode();
 151   if( op == Op_MulI || op == Op_AndI || op == Op_MulL || op == Op_AndL ) {
 152     const Type *zero = add_id();        // The multiplicative zero
 153     if( t1->higher_equal( zero ) ) return zero;
 154     if( t2->higher_equal( zero ) ) return zero;
 155   }
 156 
 157   // Either input is BOTTOM ==> the result is the local BOTTOM
 158   if( t1 == Type::BOTTOM || t2 == Type::BOTTOM )
 159     return bottom_type();
 160 
 161 #if defined(IA32)
 162   // Can't trust native compilers to properly fold strict double
 163   // multiplication with round-to-zero on this platform.
 164   if (op == Op_MulD && phase->C->method()->is_strict()) {
 165     return TypeD::DOUBLE;
 166   }
 167 #endif
 168 
 169   return mul_ring(t1,t2);            // Local flavor of type multiplication
 170 }
 171 
 172 
 173 //=============================================================================
 174 //------------------------------Ideal------------------------------------------
 175 // Check for power-of-2 multiply, then try the regular MulNode::Ideal
 176 Node *MulINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 177   // Swap constant to right
 178   jint con;
 179   if ((con = in(1)->find_int_con(0)) != 0) {
 180     swap_edges(1, 2);
 181     // Finish rest of method to use info in 'con'
 182   } else if ((con = in(2)->find_int_con(0)) == 0) {
 183     return MulNode::Ideal(phase, can_reshape);
 184   }
 185 
 186   // Now we have a constant Node on the right and the constant in con
 187   if( con == 0 ) return NULL;   // By zero is handled by Value call
 188   if( con == 1 ) return NULL;   // By one  is handled by Identity call
 189 
 190   // Check for negative constant; if so negate the final result
 191   bool sign_flip = false;
 192   if( con < 0 ) {
 193     con = -con;
 194     sign_flip = true;
 195   }
 196 
 197   // Get low bit; check for being the only bit
 198   Node *res = NULL;
 199   jint bit1 = con & -con;       // Extract low bit
 200   if( bit1 == con ) {           // Found a power of 2?
 201     res = new (phase->C) LShiftINode( in(1), phase->intcon(log2_intptr(bit1)) );
 202   } else {
 203 
 204     // Check for constant with 2 bits set
 205     jint bit2 = con-bit1;
 206     bit2 = bit2 & -bit2;          // Extract 2nd bit
 207     if( bit2 + bit1 == con ) {    // Found all bits in con?
 208       Node *n1 = phase->transform( new (phase->C) LShiftINode( in(1), phase->intcon(log2_intptr(bit1)) ) );
 209       Node *n2 = phase->transform( new (phase->C) LShiftINode( in(1), phase->intcon(log2_intptr(bit2)) ) );
 210       res = new (phase->C) AddINode( n2, n1 );
 211 
 212     } else if (is_power_of_2(con+1)) {
 213       // Sleezy: power-of-2 -1.  Next time be generic.
 214       jint temp = (jint) (con + 1);
 215       Node *n1 = phase->transform( new (phase->C) LShiftINode( in(1), phase->intcon(log2_intptr(temp)) ) );
 216       res = new (phase->C) SubINode( n1, in(1) );
 217     } else {
 218       return MulNode::Ideal(phase, can_reshape);
 219     }
 220   }
 221 
 222   if( sign_flip ) {             // Need to negate result?
 223     res = phase->transform(res);// Transform, before making the zero con
 224     res = new (phase->C) SubINode(phase->intcon(0),res);
 225   }
 226 
 227   return res;                   // Return final result
 228 }
 229 
 230 //------------------------------mul_ring---------------------------------------
 231 // Compute the product type of two integer ranges into this node.
 232 const Type *MulINode::mul_ring(const Type *t0, const Type *t1) const {
 233   const TypeInt *r0 = t0->is_int(); // Handy access
 234   const TypeInt *r1 = t1->is_int();
 235 
 236   // Fetch endpoints of all ranges
 237   int32 lo0 = r0->_lo;
 238   double a = (double)lo0;
 239   int32 hi0 = r0->_hi;
 240   double b = (double)hi0;
 241   int32 lo1 = r1->_lo;
 242   double c = (double)lo1;
 243   int32 hi1 = r1->_hi;
 244   double d = (double)hi1;
 245 
 246   // Compute all endpoints & check for overflow
 247   int32 A = java_multiply(lo0, lo1);
 248   if( (double)A != a*c ) return TypeInt::INT; // Overflow?
 249   int32 B = java_multiply(lo0, hi1);
 250   if( (double)B != a*d ) return TypeInt::INT; // Overflow?
 251   int32 C = java_multiply(hi0, lo1);
 252   if( (double)C != b*c ) return TypeInt::INT; // Overflow?
 253   int32 D = java_multiply(hi0, hi1);
 254   if( (double)D != b*d ) return TypeInt::INT; // Overflow?
 255 
 256   if( A < B ) { lo0 = A; hi0 = B; } // Sort range endpoints
 257   else { lo0 = B; hi0 = A; }
 258   if( C < D ) {
 259     if( C < lo0 ) lo0 = C;
 260     if( D > hi0 ) hi0 = D;
 261   } else {
 262     if( D < lo0 ) lo0 = D;
 263     if( C > hi0 ) hi0 = C;
 264   }
 265   return TypeInt::make(lo0, hi0, MAX2(r0->_widen,r1->_widen));
 266 }
 267 
 268 
 269 //=============================================================================
 270 //------------------------------Ideal------------------------------------------
 271 // Check for power-of-2 multiply, then try the regular MulNode::Ideal
 272 Node *MulLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 273   // Swap constant to right
 274   jlong con;
 275   if ((con = in(1)->find_long_con(0)) != 0) {
 276     swap_edges(1, 2);
 277     // Finish rest of method to use info in 'con'
 278   } else if ((con = in(2)->find_long_con(0)) == 0) {
 279     return MulNode::Ideal(phase, can_reshape);
 280   }
 281 
 282   // Now we have a constant Node on the right and the constant in con
 283   if( con == CONST64(0) ) return NULL;  // By zero is handled by Value call
 284   if( con == CONST64(1) ) return NULL;  // By one  is handled by Identity call
 285 
 286   // Check for negative constant; if so negate the final result
 287   bool sign_flip = false;
 288   if( con < 0 ) {
 289     con = -con;
 290     sign_flip = true;
 291   }
 292 
 293   // Get low bit; check for being the only bit
 294   Node *res = NULL;
 295   jlong bit1 = con & -con;      // Extract low bit
 296   if( bit1 == con ) {           // Found a power of 2?
 297     res = new (phase->C) LShiftLNode( in(1), phase->intcon(log2_long(bit1)) );
 298   } else {
 299 
 300     // Check for constant with 2 bits set
 301     jlong bit2 = con-bit1;
 302     bit2 = bit2 & -bit2;          // Extract 2nd bit
 303     if( bit2 + bit1 == con ) {    // Found all bits in con?
 304       Node *n1 = phase->transform( new (phase->C) LShiftLNode( in(1), phase->intcon(log2_long(bit1)) ) );
 305       Node *n2 = phase->transform( new (phase->C) LShiftLNode( in(1), phase->intcon(log2_long(bit2)) ) );
 306       res = new (phase->C) AddLNode( n2, n1 );
 307 
 308     } else if (is_power_of_2_long(con+1)) {
 309       // Sleezy: power-of-2 -1.  Next time be generic.
 310       jlong temp = (jlong) (con + 1);
 311       Node *n1 = phase->transform( new (phase->C) LShiftLNode( in(1), phase->intcon(log2_long(temp)) ) );
 312       res = new (phase->C) SubLNode( n1, in(1) );
 313     } else {
 314       return MulNode::Ideal(phase, can_reshape);
 315     }
 316   }
 317 
 318   if( sign_flip ) {             // Need to negate result?
 319     res = phase->transform(res);// Transform, before making the zero con
 320     res = new (phase->C) SubLNode(phase->longcon(0),res);
 321   }
 322 
 323   return res;                   // Return final result
 324 }
 325 
 326 //------------------------------mul_ring---------------------------------------
 327 // Compute the product type of two integer ranges into this node.
 328 const Type *MulLNode::mul_ring(const Type *t0, const Type *t1) const {
 329   const TypeLong *r0 = t0->is_long(); // Handy access
 330   const TypeLong *r1 = t1->is_long();
 331 
 332   // Fetch endpoints of all ranges
 333   jlong lo0 = r0->_lo;
 334   double a = (double)lo0;
 335   jlong hi0 = r0->_hi;
 336   double b = (double)hi0;
 337   jlong lo1 = r1->_lo;
 338   double c = (double)lo1;
 339   jlong hi1 = r1->_hi;
 340   double d = (double)hi1;
 341 
 342   // Compute all endpoints & check for overflow
 343   jlong A = java_multiply(lo0, lo1);
 344   if( (double)A != a*c ) return TypeLong::LONG; // Overflow?
 345   jlong B = java_multiply(lo0, hi1);
 346   if( (double)B != a*d ) return TypeLong::LONG; // Overflow?
 347   jlong C = java_multiply(hi0, lo1);
 348   if( (double)C != b*c ) return TypeLong::LONG; // Overflow?
 349   jlong D = java_multiply(hi0, hi1);
 350   if( (double)D != b*d ) return TypeLong::LONG; // Overflow?
 351 
 352   if( A < B ) { lo0 = A; hi0 = B; } // Sort range endpoints
 353   else { lo0 = B; hi0 = A; }
 354   if( C < D ) {
 355     if( C < lo0 ) lo0 = C;
 356     if( D > hi0 ) hi0 = D;
 357   } else {
 358     if( D < lo0 ) lo0 = D;
 359     if( C > hi0 ) hi0 = C;
 360   }
 361   return TypeLong::make(lo0, hi0, MAX2(r0->_widen,r1->_widen));
 362 }
 363 
 364 //=============================================================================
 365 //------------------------------mul_ring---------------------------------------
 366 // Compute the product type of two double ranges into this node.
 367 const Type *MulFNode::mul_ring(const Type *t0, const Type *t1) const {
 368   if( t0 == Type::FLOAT || t1 == Type::FLOAT ) return Type::FLOAT;
 369   return TypeF::make( t0->getf() * t1->getf() );
 370 }
 371 
 372 //=============================================================================
 373 //------------------------------mul_ring---------------------------------------
 374 // Compute the product type of two double ranges into this node.
 375 const Type *MulDNode::mul_ring(const Type *t0, const Type *t1) const {
 376   if( t0 == Type::DOUBLE || t1 == Type::DOUBLE ) return Type::DOUBLE;
 377   // We must be multiplying 2 double constants.
 378   return TypeD::make( t0->getd() * t1->getd() );
 379 }
 380 
 381 //=============================================================================
 382 //------------------------------Value------------------------------------------
 383 const Type *MulHiLNode::Value( PhaseTransform *phase ) const {
 384   // Either input is TOP ==> the result is TOP
 385   const Type *t1 = phase->type( in(1) );
 386   const Type *t2 = phase->type( in(2) );
 387   if( t1 == Type::TOP ) return Type::TOP;
 388   if( t2 == Type::TOP ) return Type::TOP;
 389 
 390   // Either input is BOTTOM ==> the result is the local BOTTOM
 391   const Type *bot = bottom_type();
 392   if( (t1 == bot) || (t2 == bot) ||
 393       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 394     return bot;
 395 
 396   // It is not worth trying to constant fold this stuff!
 397   return TypeLong::LONG;
 398 }
 399 
 400 //=============================================================================
 401 //------------------------------mul_ring---------------------------------------
 402 // Supplied function returns the product of the inputs IN THE CURRENT RING.
 403 // For the logical operations the ring's MUL is really a logical AND function.
 404 // This also type-checks the inputs for sanity.  Guaranteed never to
 405 // be passed a TOP or BOTTOM type, these are filtered out by pre-check.
 406 const Type *AndINode::mul_ring( const Type *t0, const Type *t1 ) const {
 407   const TypeInt *r0 = t0->is_int(); // Handy access
 408   const TypeInt *r1 = t1->is_int();
 409   int widen = MAX2(r0->_widen,r1->_widen);
 410 
 411   // If either input is a constant, might be able to trim cases
 412   if( !r0->is_con() && !r1->is_con() )
 413     return TypeInt::INT;        // No constants to be had
 414 
 415   // Both constants?  Return bits
 416   if( r0->is_con() && r1->is_con() )
 417     return TypeInt::make( r0->get_con() & r1->get_con() );
 418 
 419   if( r0->is_con() && r0->get_con() > 0 )
 420     return TypeInt::make(0, r0->get_con(), widen);
 421 
 422   if( r1->is_con() && r1->get_con() > 0 )
 423     return TypeInt::make(0, r1->get_con(), widen);
 424 
 425   if( r0 == TypeInt::BOOL || r1 == TypeInt::BOOL ) {
 426     return TypeInt::BOOL;
 427   }
 428 
 429   return TypeInt::INT;          // No constants to be had
 430 }
 431 
 432 //------------------------------Identity---------------------------------------
 433 // Masking off the high bits of an unsigned load is not required
 434 Node *AndINode::Identity( PhaseTransform *phase ) {
 435 
 436   // x & x => x
 437   if (phase->eqv(in(1), in(2))) return in(1);
 438 
 439   Node* in1 = in(1);
 440   uint op = in1->Opcode();
 441   const TypeInt* t2 = phase->type(in(2))->isa_int();
 442   if (t2 && t2->is_con()) {
 443     int con = t2->get_con();
 444     // Masking off high bits which are always zero is useless.
 445     const TypeInt* t1 = phase->type( in(1) )->isa_int();
 446     if (t1 != NULL && t1->_lo >= 0) {
 447       jint t1_support = right_n_bits(1 + log2_intptr(t1->_hi));
 448       if ((t1_support & con) == t1_support)
 449         return in1;
 450     }
 451     // Masking off the high bits of a unsigned-shift-right is not
 452     // needed either.
 453     if (op == Op_URShiftI) {
 454       const TypeInt* t12 = phase->type(in1->in(2))->isa_int();
 455       if (t12 && t12->is_con()) {  // Shift is by a constant
 456         int shift = t12->get_con();
 457         shift &= BitsPerJavaInteger - 1;  // semantics of Java shifts
 458         int mask = max_juint >> shift;
 459         if ((mask & con) == mask)  // If AND is useless, skip it
 460           return in1;
 461       }
 462     }
 463   }
 464   return MulNode::Identity(phase);
 465 }
 466 
 467 //------------------------------Ideal------------------------------------------
 468 Node *AndINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 469   // Special case constant AND mask
 470   const TypeInt *t2 = phase->type( in(2) )->isa_int();
 471   if( !t2 || !t2->is_con() ) return MulNode::Ideal(phase, can_reshape);
 472   const int mask = t2->get_con();
 473   Node *load = in(1);
 474   uint lop = load->Opcode();
 475 
 476   // Masking bits off of a Character?  Hi bits are already zero.
 477   if( lop == Op_LoadUS &&
 478       (mask & 0xFFFF0000) )     // Can we make a smaller mask?
 479     return new (phase->C) AndINode(load,phase->intcon(mask&0xFFFF));
 480 
 481   // Masking bits off of a Short?  Loading a Character does some masking
 482   if (can_reshape &&
 483       load->outcnt() == 1 && load->unique_out() == this) {
 484     if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
 485       Node *ldus = new (phase->C) LoadUSNode(load->in(MemNode::Control),
 486                                              load->in(MemNode::Memory),
 487                                              load->in(MemNode::Address),
 488                                              load->adr_type(),
 489                                              TypeInt::CHAR, MemNode::unordered);
 490       ldus = phase->transform(ldus);
 491       return new (phase->C) AndINode(ldus, phase->intcon(mask & 0xFFFF));
 492     }
 493 
 494     // Masking sign bits off of a Byte?  Do an unsigned byte load plus
 495     // an and.
 496     if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
 497       Node* ldub = new (phase->C) LoadUBNode(load->in(MemNode::Control),
 498                                              load->in(MemNode::Memory),
 499                                              load->in(MemNode::Address),
 500                                              load->adr_type(),
 501                                              TypeInt::UBYTE, MemNode::unordered);
 502       ldub = phase->transform(ldub);
 503       return new (phase->C) AndINode(ldub, phase->intcon(mask));
 504     }
 505   }
 506 
 507   // Masking off sign bits?  Dont make them!
 508   if( lop == Op_RShiftI ) {
 509     const TypeInt *t12 = phase->type(load->in(2))->isa_int();
 510     if( t12 && t12->is_con() ) { // Shift is by a constant
 511       int shift = t12->get_con();
 512       shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 513       const int sign_bits_mask = ~right_n_bits(BitsPerJavaInteger - shift);
 514       // If the AND'ing of the 2 masks has no bits, then only original shifted
 515       // bits survive.  NO sign-extension bits survive the maskings.
 516       if( (sign_bits_mask & mask) == 0 ) {
 517         // Use zero-fill shift instead
 518         Node *zshift = phase->transform(new (phase->C) URShiftINode(load->in(1),load->in(2)));
 519         return new (phase->C) AndINode( zshift, in(2) );
 520       }
 521     }
 522   }
 523 
 524   // Check for 'negate/and-1', a pattern emitted when someone asks for
 525   // 'mod 2'.  Negate leaves the low order bit unchanged (think: complement
 526   // plus 1) and the mask is of the low order bit.  Skip the negate.
 527   if( lop == Op_SubI && mask == 1 && load->in(1) &&
 528       phase->type(load->in(1)) == TypeInt::ZERO )
 529     return new (phase->C) AndINode( load->in(2), in(2) );
 530 
 531   return MulNode::Ideal(phase, can_reshape);
 532 }
 533 
 534 //=============================================================================
 535 //------------------------------mul_ring---------------------------------------
 536 // Supplied function returns the product of the inputs IN THE CURRENT RING.
 537 // For the logical operations the ring's MUL is really a logical AND function.
 538 // This also type-checks the inputs for sanity.  Guaranteed never to
 539 // be passed a TOP or BOTTOM type, these are filtered out by pre-check.
 540 const Type *AndLNode::mul_ring( const Type *t0, const Type *t1 ) const {
 541   const TypeLong *r0 = t0->is_long(); // Handy access
 542   const TypeLong *r1 = t1->is_long();
 543   int widen = MAX2(r0->_widen,r1->_widen);
 544 
 545   // If either input is a constant, might be able to trim cases
 546   if( !r0->is_con() && !r1->is_con() )
 547     return TypeLong::LONG;      // No constants to be had
 548 
 549   // Both constants?  Return bits
 550   if( r0->is_con() && r1->is_con() )
 551     return TypeLong::make( r0->get_con() & r1->get_con() );
 552 
 553   if( r0->is_con() && r0->get_con() > 0 )
 554     return TypeLong::make(CONST64(0), r0->get_con(), widen);
 555 
 556   if( r1->is_con() && r1->get_con() > 0 )
 557     return TypeLong::make(CONST64(0), r1->get_con(), widen);
 558 
 559   return TypeLong::LONG;        // No constants to be had
 560 }
 561 
 562 //------------------------------Identity---------------------------------------
 563 // Masking off the high bits of an unsigned load is not required
 564 Node *AndLNode::Identity( PhaseTransform *phase ) {
 565 
 566   // x & x => x
 567   if (phase->eqv(in(1), in(2))) return in(1);
 568 
 569   Node *usr = in(1);
 570   const TypeLong *t2 = phase->type( in(2) )->isa_long();
 571   if( t2 && t2->is_con() ) {
 572     jlong con = t2->get_con();
 573     // Masking off high bits which are always zero is useless.
 574     const TypeLong* t1 = phase->type( in(1) )->isa_long();
 575     if (t1 != NULL && t1->_lo >= 0) {
 576       int bit_count = log2_long(t1->_hi) + 1;
 577       jlong t1_support = jlong(max_julong >> (BitsPerJavaLong - bit_count));
 578       if ((t1_support & con) == t1_support)
 579         return usr;
 580     }
 581     uint lop = usr->Opcode();
 582     // Masking off the high bits of a unsigned-shift-right is not
 583     // needed either.
 584     if( lop == Op_URShiftL ) {
 585       const TypeInt *t12 = phase->type( usr->in(2) )->isa_int();
 586       if( t12 && t12->is_con() ) {  // Shift is by a constant
 587         int shift = t12->get_con();
 588         shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 589         jlong mask = max_julong >> shift;
 590         if( (mask&con) == mask )  // If AND is useless, skip it
 591           return usr;
 592       }
 593     }
 594   }
 595   return MulNode::Identity(phase);
 596 }
 597 
 598 //------------------------------Ideal------------------------------------------
 599 Node *AndLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 600   // Special case constant AND mask
 601   const TypeLong *t2 = phase->type( in(2) )->isa_long();
 602   if( !t2 || !t2->is_con() ) return MulNode::Ideal(phase, can_reshape);
 603   const jlong mask = t2->get_con();
 604 
 605   Node* in1 = in(1);
 606   uint op = in1->Opcode();
 607 
 608   // Are we masking a long that was converted from an int with a mask
 609   // that fits in 32-bits?  Commute them and use an AndINode.  Don't
 610   // convert masks which would cause a sign extension of the integer
 611   // value.  This check includes UI2L masks (0x00000000FFFFFFFF) which
 612   // would be optimized away later in Identity.
 613   if (op == Op_ConvI2L && (mask & CONST64(0xFFFFFFFF80000000)) == 0) {
 614     Node* andi = new (phase->C) AndINode(in1->in(1), phase->intcon(mask));
 615     andi = phase->transform(andi);
 616     return new (phase->C) ConvI2LNode(andi);
 617   }
 618 
 619   // Masking off sign bits?  Dont make them!
 620   if (op == Op_RShiftL) {
 621     const TypeInt* t12 = phase->type(in1->in(2))->isa_int();
 622     if( t12 && t12->is_con() ) { // Shift is by a constant
 623       int shift = t12->get_con();
 624       shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 625       const jlong sign_bits_mask = ~(((jlong)CONST64(1) << (jlong)(BitsPerJavaLong - shift)) -1);
 626       // If the AND'ing of the 2 masks has no bits, then only original shifted
 627       // bits survive.  NO sign-extension bits survive the maskings.
 628       if( (sign_bits_mask & mask) == 0 ) {
 629         // Use zero-fill shift instead
 630         Node *zshift = phase->transform(new (phase->C) URShiftLNode(in1->in(1), in1->in(2)));
 631         return new (phase->C) AndLNode(zshift, in(2));
 632       }
 633     }
 634   }
 635 
 636   return MulNode::Ideal(phase, can_reshape);
 637 }
 638 
 639 //=============================================================================
 640 //------------------------------Identity---------------------------------------
 641 Node *LShiftINode::Identity( PhaseTransform *phase ) {
 642   const TypeInt *ti = phase->type( in(2) )->isa_int();  // shift count is an int
 643   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerInt - 1 ) ) == 0 ) ? in(1) : this;
 644 }
 645 
 646 //------------------------------Ideal------------------------------------------
 647 // If the right input is a constant, and the left input is an add of a
 648 // constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
 649 Node *LShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 650   const Type *t  = phase->type( in(2) );
 651   if( t == Type::TOP ) return NULL;       // Right input is dead
 652   const TypeInt *t2 = t->isa_int();
 653   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 654   const int con = t2->get_con() & ( BitsPerInt - 1 );  // masked shift count
 655 
 656   if ( con == 0 )  return NULL; // let Identity() handle 0 shift count
 657 
 658   // Left input is an add of a constant?
 659   Node *add1 = in(1);
 660   int add1_op = add1->Opcode();
 661   if( add1_op == Op_AddI ) {    // Left input is an add?
 662     assert( add1 != add1->in(1), "dead loop in LShiftINode::Ideal" );
 663     const TypeInt *t12 = phase->type(add1->in(2))->isa_int();
 664     if( t12 && t12->is_con() ){ // Left input is an add of a con?
 665       // Transform is legal, but check for profit.  Avoid breaking 'i2s'
 666       // and 'i2b' patterns which typically fold into 'StoreC/StoreB'.
 667       if( con < 16 ) {
 668         // Compute X << con0
 669         Node *lsh = phase->transform( new (phase->C) LShiftINode( add1->in(1), in(2) ) );
 670         // Compute X<<con0 + (con1<<con0)
 671         return new (phase->C) AddINode( lsh, phase->intcon(t12->get_con() << con));
 672       }
 673     }
 674   }
 675 
 676   // Check for "(x>>c0)<<c0" which just masks off low bits
 677   if( (add1_op == Op_RShiftI || add1_op == Op_URShiftI ) &&
 678       add1->in(2) == in(2) )
 679     // Convert to "(x & -(1<<c0))"
 680     return new (phase->C) AndINode(add1->in(1),phase->intcon( -(1<<con)));
 681 
 682   // Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
 683   if( add1_op == Op_AndI ) {
 684     Node *add2 = add1->in(1);
 685     int add2_op = add2->Opcode();
 686     if( (add2_op == Op_RShiftI || add2_op == Op_URShiftI ) &&
 687         add2->in(2) == in(2) ) {
 688       // Convert to "(x & (Y<<c0))"
 689       Node *y_sh = phase->transform( new (phase->C) LShiftINode( add1->in(2), in(2) ) );
 690       return new (phase->C) AndINode( add2->in(1), y_sh );
 691     }
 692   }
 693 
 694   // Check for ((x & ((1<<(32-c0))-1)) << c0) which ANDs off high bits
 695   // before shifting them away.
 696   const jint bits_mask = right_n_bits(BitsPerJavaInteger-con);
 697   if( add1_op == Op_AndI &&
 698       phase->type(add1->in(2)) == TypeInt::make( bits_mask ) )
 699     return new (phase->C) LShiftINode( add1->in(1), in(2) );
 700 
 701   return NULL;
 702 }
 703 
 704 //------------------------------Value------------------------------------------
 705 // A LShiftINode shifts its input2 left by input1 amount.
 706 const Type *LShiftINode::Value( PhaseTransform *phase ) const {
 707   const Type *t1 = phase->type( in(1) );
 708   const Type *t2 = phase->type( in(2) );
 709   // Either input is TOP ==> the result is TOP
 710   if( t1 == Type::TOP ) return Type::TOP;
 711   if( t2 == Type::TOP ) return Type::TOP;
 712 
 713   // Left input is ZERO ==> the result is ZERO.
 714   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
 715   // Shift by zero does nothing
 716   if( t2 == TypeInt::ZERO ) return t1;
 717 
 718   // Either input is BOTTOM ==> the result is BOTTOM
 719   if( (t1 == TypeInt::INT) || (t2 == TypeInt::INT) ||
 720       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 721     return TypeInt::INT;
 722 
 723   const TypeInt *r1 = t1->is_int(); // Handy access
 724   const TypeInt *r2 = t2->is_int(); // Handy access
 725 
 726   if (!r2->is_con())
 727     return TypeInt::INT;
 728 
 729   uint shift = r2->get_con();
 730   shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 731   // Shift by a multiple of 32 does nothing:
 732   if (shift == 0)  return t1;
 733 
 734   // If the shift is a constant, shift the bounds of the type,
 735   // unless this could lead to an overflow.
 736   if (!r1->is_con()) {
 737     jint lo = r1->_lo, hi = r1->_hi;
 738     if (((lo << shift) >> shift) == lo &&
 739         ((hi << shift) >> shift) == hi) {
 740       // No overflow.  The range shifts up cleanly.
 741       return TypeInt::make((jint)lo << (jint)shift,
 742                            (jint)hi << (jint)shift,
 743                            MAX2(r1->_widen,r2->_widen));
 744     }
 745     return TypeInt::INT;
 746   }
 747 
 748   return TypeInt::make( (jint)r1->get_con() << (jint)shift );
 749 }
 750 
 751 //=============================================================================
 752 //------------------------------Identity---------------------------------------
 753 Node *LShiftLNode::Identity( PhaseTransform *phase ) {
 754   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
 755   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
 756 }
 757 
 758 //------------------------------Ideal------------------------------------------
 759 // If the right input is a constant, and the left input is an add of a
 760 // constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
 761 Node *LShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 762   const Type *t  = phase->type( in(2) );
 763   if( t == Type::TOP ) return NULL;       // Right input is dead
 764   const TypeInt *t2 = t->isa_int();
 765   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 766   const int con = t2->get_con() & ( BitsPerLong - 1 );  // masked shift count
 767 
 768   if ( con == 0 ) return NULL;  // let Identity() handle 0 shift count
 769 
 770   // Left input is an add of a constant?
 771   Node *add1 = in(1);
 772   int add1_op = add1->Opcode();
 773   if( add1_op == Op_AddL ) {    // Left input is an add?
 774     // Avoid dead data cycles from dead loops
 775     assert( add1 != add1->in(1), "dead loop in LShiftLNode::Ideal" );
 776     const TypeLong *t12 = phase->type(add1->in(2))->isa_long();
 777     if( t12 && t12->is_con() ){ // Left input is an add of a con?
 778       // Compute X << con0
 779       Node *lsh = phase->transform( new (phase->C) LShiftLNode( add1->in(1), in(2) ) );
 780       // Compute X<<con0 + (con1<<con0)
 781       return new (phase->C) AddLNode( lsh, phase->longcon(t12->get_con() << con));
 782     }
 783   }
 784 
 785   // Check for "(x>>c0)<<c0" which just masks off low bits
 786   if( (add1_op == Op_RShiftL || add1_op == Op_URShiftL ) &&
 787       add1->in(2) == in(2) )
 788     // Convert to "(x & -(1<<c0))"
 789     return new (phase->C) AndLNode(add1->in(1),phase->longcon( -(CONST64(1)<<con)));
 790 
 791   // Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
 792   if( add1_op == Op_AndL ) {
 793     Node *add2 = add1->in(1);
 794     int add2_op = add2->Opcode();
 795     if( (add2_op == Op_RShiftL || add2_op == Op_URShiftL ) &&
 796         add2->in(2) == in(2) ) {
 797       // Convert to "(x & (Y<<c0))"
 798       Node *y_sh = phase->transform( new (phase->C) LShiftLNode( add1->in(2), in(2) ) );
 799       return new (phase->C) AndLNode( add2->in(1), y_sh );
 800     }
 801   }
 802 
 803   // Check for ((x & ((CONST64(1)<<(64-c0))-1)) << c0) which ANDs off high bits
 804   // before shifting them away.
 805   const jlong bits_mask = jlong(max_julong >> con);
 806   if( add1_op == Op_AndL &&
 807       phase->type(add1->in(2)) == TypeLong::make( bits_mask ) )
 808     return new (phase->C) LShiftLNode( add1->in(1), in(2) );
 809 
 810   return NULL;
 811 }
 812 
 813 //------------------------------Value------------------------------------------
 814 // A LShiftLNode shifts its input2 left by input1 amount.
 815 const Type *LShiftLNode::Value( PhaseTransform *phase ) const {
 816   const Type *t1 = phase->type( in(1) );
 817   const Type *t2 = phase->type( in(2) );
 818   // Either input is TOP ==> the result is TOP
 819   if( t1 == Type::TOP ) return Type::TOP;
 820   if( t2 == Type::TOP ) return Type::TOP;
 821 
 822   // Left input is ZERO ==> the result is ZERO.
 823   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
 824   // Shift by zero does nothing
 825   if( t2 == TypeInt::ZERO ) return t1;
 826 
 827   // Either input is BOTTOM ==> the result is BOTTOM
 828   if( (t1 == TypeLong::LONG) || (t2 == TypeInt::INT) ||
 829       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 830     return TypeLong::LONG;
 831 
 832   const TypeLong *r1 = t1->is_long(); // Handy access
 833   const TypeInt  *r2 = t2->is_int();  // Handy access
 834 
 835   if (!r2->is_con())
 836     return TypeLong::LONG;
 837 
 838   uint shift = r2->get_con();
 839   shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 840   // Shift by a multiple of 64 does nothing:
 841   if (shift == 0)  return t1;
 842 
 843   // If the shift is a constant, shift the bounds of the type,
 844   // unless this could lead to an overflow.
 845   if (!r1->is_con()) {
 846     jlong lo = r1->_lo, hi = r1->_hi;
 847     if (((lo << shift) >> shift) == lo &&
 848         ((hi << shift) >> shift) == hi) {
 849       // No overflow.  The range shifts up cleanly.
 850       return TypeLong::make((jlong)lo << (jint)shift,
 851                             (jlong)hi << (jint)shift,
 852                             MAX2(r1->_widen,r2->_widen));
 853     }
 854     return TypeLong::LONG;
 855   }
 856 
 857   return TypeLong::make( (jlong)r1->get_con() << (jint)shift );
 858 }
 859 
 860 //=============================================================================
 861 //------------------------------Identity---------------------------------------
 862 Node *RShiftINode::Identity( PhaseTransform *phase ) {
 863   const TypeInt *t2 = phase->type(in(2))->isa_int();
 864   if( !t2 ) return this;
 865   if ( t2->is_con() && ( t2->get_con() & ( BitsPerInt - 1 ) ) == 0 )
 866     return in(1);
 867 
 868   // Check for useless sign-masking
 869   if( in(1)->Opcode() == Op_LShiftI &&
 870       in(1)->req() == 3 &&
 871       in(1)->in(2) == in(2) &&
 872       t2->is_con() ) {
 873     uint shift = t2->get_con();
 874     shift &= BitsPerJavaInteger-1; // semantics of Java shifts
 875     // Compute masks for which this shifting doesn't change
 876     int lo = (-1 << (BitsPerJavaInteger - shift-1)); // FFFF8000
 877     int hi = ~lo;               // 00007FFF
 878     const TypeInt *t11 = phase->type(in(1)->in(1))->isa_int();
 879     if( !t11 ) return this;
 880     // Does actual value fit inside of mask?
 881     if( lo <= t11->_lo && t11->_hi <= hi )
 882       return in(1)->in(1);      // Then shifting is a nop
 883   }
 884 
 885   return this;
 886 }
 887 
 888 //------------------------------Ideal------------------------------------------
 889 Node *RShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 890   // Inputs may be TOP if they are dead.
 891   const TypeInt *t1 = phase->type( in(1) )->isa_int();
 892   if( !t1 ) return NULL;        // Left input is an integer
 893   const TypeInt *t2 = phase->type( in(2) )->isa_int();
 894   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 895   const TypeInt *t3;  // type of in(1).in(2)
 896   int shift = t2->get_con();
 897   shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 898 
 899   if ( shift == 0 ) return NULL;  // let Identity() handle 0 shift count
 900 
 901   // Check for (x & 0xFF000000) >> 24, whose mask can be made smaller.
 902   // Such expressions arise normally from shift chains like (byte)(x >> 24).
 903   const Node *mask = in(1);
 904   if( mask->Opcode() == Op_AndI &&
 905       (t3 = phase->type(mask->in(2))->isa_int()) &&
 906       t3->is_con() ) {
 907     Node *x = mask->in(1);
 908     jint maskbits = t3->get_con();
 909     // Convert to "(x >> shift) & (mask >> shift)"
 910     Node *shr_nomask = phase->transform( new (phase->C) RShiftINode(mask->in(1), in(2)) );
 911     return new (phase->C) AndINode(shr_nomask, phase->intcon( maskbits >> shift));
 912   }
 913 
 914   // Check for "(short[i] <<16)>>16" which simply sign-extends
 915   const Node *shl = in(1);
 916   if( shl->Opcode() != Op_LShiftI ) return NULL;
 917 
 918   if( shift == 16 &&
 919       (t3 = phase->type(shl->in(2))->isa_int()) &&
 920       t3->is_con(16) ) {
 921     Node *ld = shl->in(1);
 922     if( ld->Opcode() == Op_LoadS ) {
 923       // Sign extension is just useless here.  Return a RShiftI of zero instead
 924       // returning 'ld' directly.  We cannot return an old Node directly as
 925       // that is the job of 'Identity' calls and Identity calls only work on
 926       // direct inputs ('ld' is an extra Node removed from 'this').  The
 927       // combined optimization requires Identity only return direct inputs.
 928       set_req(1, ld);
 929       set_req(2, phase->intcon(0));
 930       return this;
 931     }
 932     else if( can_reshape &&
 933              ld->Opcode() == Op_LoadUS &&
 934              ld->outcnt() == 1 && ld->unique_out() == shl)
 935       // Replace zero-extension-load with sign-extension-load
 936       return new (phase->C) LoadSNode( ld->in(MemNode::Control),
 937                                        ld->in(MemNode::Memory),
 938                                        ld->in(MemNode::Address),
 939                                        ld->adr_type(), TypeInt::SHORT,
 940                                        MemNode::unordered);
 941   }
 942 
 943   // Check for "(byte[i] <<24)>>24" which simply sign-extends
 944   if( shift == 24 &&
 945       (t3 = phase->type(shl->in(2))->isa_int()) &&
 946       t3->is_con(24) ) {
 947     Node *ld = shl->in(1);
 948     if( ld->Opcode() == Op_LoadB ) {
 949       // Sign extension is just useless here
 950       set_req(1, ld);
 951       set_req(2, phase->intcon(0));
 952       return this;
 953     }
 954   }
 955 
 956   return NULL;
 957 }
 958 
 959 //------------------------------Value------------------------------------------
 960 // A RShiftINode shifts its input2 right by input1 amount.
 961 const Type *RShiftINode::Value( PhaseTransform *phase ) const {
 962   const Type *t1 = phase->type( in(1) );
 963   const Type *t2 = phase->type( in(2) );
 964   // Either input is TOP ==> the result is TOP
 965   if( t1 == Type::TOP ) return Type::TOP;
 966   if( t2 == Type::TOP ) return Type::TOP;
 967 
 968   // Left input is ZERO ==> the result is ZERO.
 969   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
 970   // Shift by zero does nothing
 971   if( t2 == TypeInt::ZERO ) return t1;
 972 
 973   // Either input is BOTTOM ==> the result is BOTTOM
 974   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
 975     return TypeInt::INT;
 976 
 977   if (t2 == TypeInt::INT)
 978     return TypeInt::INT;
 979 
 980   const TypeInt *r1 = t1->is_int(); // Handy access
 981   const TypeInt *r2 = t2->is_int(); // Handy access
 982 
 983   // If the shift is a constant, just shift the bounds of the type.
 984   // For example, if the shift is 31, we just propagate sign bits.
 985   if (r2->is_con()) {
 986     uint shift = r2->get_con();
 987     shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 988     // Shift by a multiple of 32 does nothing:
 989     if (shift == 0)  return t1;
 990     // Calculate reasonably aggressive bounds for the result.
 991     // This is necessary if we are to correctly type things
 992     // like (x<<24>>24) == ((byte)x).
 993     jint lo = (jint)r1->_lo >> (jint)shift;
 994     jint hi = (jint)r1->_hi >> (jint)shift;
 995     assert(lo <= hi, "must have valid bounds");
 996     const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
 997 #ifdef ASSERT
 998     // Make sure we get the sign-capture idiom correct.
 999     if (shift == BitsPerJavaInteger-1) {
1000       if (r1->_lo >= 0) assert(ti == TypeInt::ZERO,    ">>31 of + is  0");
1001       if (r1->_hi <  0) assert(ti == TypeInt::MINUS_1, ">>31 of - is -1");
1002     }
1003 #endif
1004     return ti;
1005   }
1006 
1007   if( !r1->is_con() || !r2->is_con() )
1008     return TypeInt::INT;
1009 
1010   // Signed shift right
1011   return TypeInt::make( r1->get_con() >> (r2->get_con()&31) );
1012 }
1013 
1014 //=============================================================================
1015 //------------------------------Identity---------------------------------------
1016 Node *RShiftLNode::Identity( PhaseTransform *phase ) {
1017   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
1018   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
1019 }
1020 
1021 //------------------------------Value------------------------------------------
1022 // A RShiftLNode shifts its input2 right by input1 amount.
1023 const Type *RShiftLNode::Value( PhaseTransform *phase ) const {
1024   const Type *t1 = phase->type( in(1) );
1025   const Type *t2 = phase->type( in(2) );
1026   // Either input is TOP ==> the result is TOP
1027   if( t1 == Type::TOP ) return Type::TOP;
1028   if( t2 == Type::TOP ) return Type::TOP;
1029 
1030   // Left input is ZERO ==> the result is ZERO.
1031   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
1032   // Shift by zero does nothing
1033   if( t2 == TypeInt::ZERO ) return t1;
1034 
1035   // Either input is BOTTOM ==> the result is BOTTOM
1036   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1037     return TypeLong::LONG;
1038 
1039   if (t2 == TypeInt::INT)
1040     return TypeLong::LONG;
1041 
1042   const TypeLong *r1 = t1->is_long(); // Handy access
1043   const TypeInt  *r2 = t2->is_int (); // Handy access
1044 
1045   // If the shift is a constant, just shift the bounds of the type.
1046   // For example, if the shift is 63, we just propagate sign bits.
1047   if (r2->is_con()) {
1048     uint shift = r2->get_con();
1049     shift &= (2*BitsPerJavaInteger)-1;  // semantics of Java shifts
1050     // Shift by a multiple of 64 does nothing:
1051     if (shift == 0)  return t1;
1052     // Calculate reasonably aggressive bounds for the result.
1053     // This is necessary if we are to correctly type things
1054     // like (x<<24>>24) == ((byte)x).
1055     jlong lo = (jlong)r1->_lo >> (jlong)shift;
1056     jlong hi = (jlong)r1->_hi >> (jlong)shift;
1057     assert(lo <= hi, "must have valid bounds");
1058     const TypeLong* tl = TypeLong::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1059     #ifdef ASSERT
1060     // Make sure we get the sign-capture idiom correct.
1061     if (shift == (2*BitsPerJavaInteger)-1) {
1062       if (r1->_lo >= 0) assert(tl == TypeLong::ZERO,    ">>63 of + is 0");
1063       if (r1->_hi < 0)  assert(tl == TypeLong::MINUS_1, ">>63 of - is -1");
1064     }
1065     #endif
1066     return tl;
1067   }
1068 
1069   return TypeLong::LONG;                // Give up
1070 }
1071 
1072 //=============================================================================
1073 //------------------------------Identity---------------------------------------
1074 Node *URShiftINode::Identity( PhaseTransform *phase ) {
1075   const TypeInt *ti = phase->type( in(2) )->isa_int();
1076   if ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerInt - 1 ) ) == 0 ) return in(1);
1077 
1078   // Check for "((x << LogBytesPerWord) + (wordSize-1)) >> LogBytesPerWord" which is just "x".
1079   // Happens during new-array length computation.
1080   // Safe if 'x' is in the range [0..(max_int>>LogBytesPerWord)]
1081   Node *add = in(1);
1082   if( add->Opcode() == Op_AddI ) {
1083     const TypeInt *t2  = phase->type(add->in(2))->isa_int();
1084     if( t2 && t2->is_con(wordSize - 1) &&
1085         add->in(1)->Opcode() == Op_LShiftI ) {
1086       // Check that shift_counts are LogBytesPerWord
1087       Node          *lshift_count   = add->in(1)->in(2);
1088       const TypeInt *t_lshift_count = phase->type(lshift_count)->isa_int();
1089       if( t_lshift_count && t_lshift_count->is_con(LogBytesPerWord) &&
1090           t_lshift_count == phase->type(in(2)) ) {
1091         Node          *x   = add->in(1)->in(1);
1092         const TypeInt *t_x = phase->type(x)->isa_int();
1093         if( t_x != NULL && 0 <= t_x->_lo && t_x->_hi <= (max_jint>>LogBytesPerWord) ) {
1094           return x;
1095         }
1096       }
1097     }
1098   }
1099 
1100   return (phase->type(in(2))->higher_equal(TypeInt::ZERO)) ? in(1) : this;
1101 }
1102 
1103 //------------------------------Ideal------------------------------------------
1104 Node *URShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
1105   const TypeInt *t2 = phase->type( in(2) )->isa_int();
1106   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
1107   const int con = t2->get_con() & 31; // Shift count is always masked
1108   if ( con == 0 ) return NULL;  // let Identity() handle a 0 shift count
1109   // We'll be wanting the right-shift amount as a mask of that many bits
1110   const int mask = right_n_bits(BitsPerJavaInteger - con);
1111 
1112   int in1_op = in(1)->Opcode();
1113 
1114   // Check for ((x>>>a)>>>b) and replace with (x>>>(a+b)) when a+b < 32
1115   if( in1_op == Op_URShiftI ) {
1116     const TypeInt *t12 = phase->type( in(1)->in(2) )->isa_int();
1117     if( t12 && t12->is_con() ) { // Right input is a constant
1118       assert( in(1) != in(1)->in(1), "dead loop in URShiftINode::Ideal" );
1119       const int con2 = t12->get_con() & 31; // Shift count is always masked
1120       const int con3 = con+con2;
1121       if( con3 < 32 )           // Only merge shifts if total is < 32
1122         return new (phase->C) URShiftINode( in(1)->in(1), phase->intcon(con3) );
1123     }
1124   }
1125 
1126   // Check for ((x << z) + Y) >>> z.  Replace with x + con>>>z
1127   // The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
1128   // If Q is "X << z" the rounding is useless.  Look for patterns like
1129   // ((X<<Z) + Y) >>> Z  and replace with (X + Y>>>Z) & Z-mask.
1130   Node *add = in(1);
1131   if( in1_op == Op_AddI ) {
1132     Node *lshl = add->in(1);
1133     if( lshl->Opcode() == Op_LShiftI &&
1134         phase->type(lshl->in(2)) == t2 ) {
1135       Node *y_z = phase->transform( new (phase->C) URShiftINode(add->in(2),in(2)) );
1136       Node *sum = phase->transform( new (phase->C) AddINode( lshl->in(1), y_z ) );
1137       return new (phase->C) AndINode( sum, phase->intcon(mask) );
1138     }
1139   }
1140 
1141   // Check for (x & mask) >>> z.  Replace with (x >>> z) & (mask >>> z)
1142   // This shortens the mask.  Also, if we are extracting a high byte and
1143   // storing it to a buffer, the mask will be removed completely.
1144   Node *andi = in(1);
1145   if( in1_op == Op_AndI ) {
1146     const TypeInt *t3 = phase->type( andi->in(2) )->isa_int();
1147     if( t3 && t3->is_con() ) { // Right input is a constant
1148       jint mask2 = t3->get_con();
1149       mask2 >>= con;  // *signed* shift downward (high-order zeroes do not help)
1150       Node *newshr = phase->transform( new (phase->C) URShiftINode(andi->in(1), in(2)) );
1151       return new (phase->C) AndINode(newshr, phase->intcon(mask2));
1152       // The negative values are easier to materialize than positive ones.
1153       // A typical case from address arithmetic is ((x & ~15) >> 4).
1154       // It's better to change that to ((x >> 4) & ~0) versus
1155       // ((x >> 4) & 0x0FFFFFFF).  The difference is greatest in LP64.
1156     }
1157   }
1158 
1159   // Check for "(X << z ) >>> z" which simply zero-extends
1160   Node *shl = in(1);
1161   if( in1_op == Op_LShiftI &&
1162       phase->type(shl->in(2)) == t2 )
1163     return new (phase->C) AndINode( shl->in(1), phase->intcon(mask) );
1164 
1165   return NULL;
1166 }
1167 
1168 //------------------------------Value------------------------------------------
1169 // A URShiftINode shifts its input2 right by input1 amount.
1170 const Type *URShiftINode::Value( PhaseTransform *phase ) const {
1171   // (This is a near clone of RShiftINode::Value.)
1172   const Type *t1 = phase->type( in(1) );
1173   const Type *t2 = phase->type( in(2) );
1174   // Either input is TOP ==> the result is TOP
1175   if( t1 == Type::TOP ) return Type::TOP;
1176   if( t2 == Type::TOP ) return Type::TOP;
1177 
1178   // Left input is ZERO ==> the result is ZERO.
1179   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
1180   // Shift by zero does nothing
1181   if( t2 == TypeInt::ZERO ) return t1;
1182 
1183   // Either input is BOTTOM ==> the result is BOTTOM
1184   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1185     return TypeInt::INT;
1186 
1187   if (t2 == TypeInt::INT)
1188     return TypeInt::INT;
1189 
1190   const TypeInt *r1 = t1->is_int();     // Handy access
1191   const TypeInt *r2 = t2->is_int();     // Handy access
1192 
1193   if (r2->is_con()) {
1194     uint shift = r2->get_con();
1195     shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
1196     // Shift by a multiple of 32 does nothing:
1197     if (shift == 0)  return t1;
1198     // Calculate reasonably aggressive bounds for the result.
1199     jint lo = (juint)r1->_lo >> (juint)shift;
1200     jint hi = (juint)r1->_hi >> (juint)shift;
1201     if (r1->_hi >= 0 && r1->_lo < 0) {
1202       // If the type has both negative and positive values,
1203       // there are two separate sub-domains to worry about:
1204       // The positive half and the negative half.
1205       jint neg_lo = lo;
1206       jint neg_hi = (juint)-1 >> (juint)shift;
1207       jint pos_lo = (juint) 0 >> (juint)shift;
1208       jint pos_hi = hi;
1209       lo = MIN2(neg_lo, pos_lo);  // == 0
1210       hi = MAX2(neg_hi, pos_hi);  // == -1 >>> shift;
1211     }
1212     assert(lo <= hi, "must have valid bounds");
1213     const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1214     #ifdef ASSERT
1215     // Make sure we get the sign-capture idiom correct.
1216     if (shift == BitsPerJavaInteger-1) {
1217       if (r1->_lo >= 0) assert(ti == TypeInt::ZERO, ">>>31 of + is 0");
1218       if (r1->_hi < 0)  assert(ti == TypeInt::ONE,  ">>>31 of - is +1");
1219     }
1220     #endif
1221     return ti;
1222   }
1223 
1224   //
1225   // Do not support shifted oops in info for GC
1226   //
1227   // else if( t1->base() == Type::InstPtr ) {
1228   //
1229   //   const TypeInstPtr *o = t1->is_instptr();
1230   //   if( t1->singleton() )
1231   //     return TypeInt::make( ((uint32)o->const_oop() + o->_offset) >> shift );
1232   // }
1233   // else if( t1->base() == Type::KlassPtr ) {
1234   //   const TypeKlassPtr *o = t1->is_klassptr();
1235   //   if( t1->singleton() )
1236   //     return TypeInt::make( ((uint32)o->const_oop() + o->_offset) >> shift );
1237   // }
1238 
1239   return TypeInt::INT;
1240 }
1241 
1242 //=============================================================================
1243 //------------------------------Identity---------------------------------------
1244 Node *URShiftLNode::Identity( PhaseTransform *phase ) {
1245   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
1246   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
1247 }
1248 
1249 //------------------------------Ideal------------------------------------------
1250 Node *URShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1251   const TypeInt *t2 = phase->type( in(2) )->isa_int();
1252   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
1253   const int con = t2->get_con() & ( BitsPerLong - 1 ); // Shift count is always masked
1254   if ( con == 0 ) return NULL;  // let Identity() handle a 0 shift count
1255                               // note: mask computation below does not work for 0 shift count
1256   // We'll be wanting the right-shift amount as a mask of that many bits
1257   const jlong mask = jlong(max_julong >> con);
1258 
1259   // Check for ((x << z) + Y) >>> z.  Replace with x + con>>>z
1260   // The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
1261   // If Q is "X << z" the rounding is useless.  Look for patterns like
1262   // ((X<<Z) + Y) >>> Z  and replace with (X + Y>>>Z) & Z-mask.
1263   Node *add = in(1);
1264   if( add->Opcode() == Op_AddL ) {
1265     Node *lshl = add->in(1);
1266     if( lshl->Opcode() == Op_LShiftL &&
1267         phase->type(lshl->in(2)) == t2 ) {
1268       Node *y_z = phase->transform( new (phase->C) URShiftLNode(add->in(2),in(2)) );
1269       Node *sum = phase->transform( new (phase->C) AddLNode( lshl->in(1), y_z ) );
1270       return new (phase->C) AndLNode( sum, phase->longcon(mask) );
1271     }
1272   }
1273 
1274   // Check for (x & mask) >>> z.  Replace with (x >>> z) & (mask >>> z)
1275   // This shortens the mask.  Also, if we are extracting a high byte and
1276   // storing it to a buffer, the mask will be removed completely.
1277   Node *andi = in(1);
1278   if( andi->Opcode() == Op_AndL ) {
1279     const TypeLong *t3 = phase->type( andi->in(2) )->isa_long();
1280     if( t3 && t3->is_con() ) { // Right input is a constant
1281       jlong mask2 = t3->get_con();
1282       mask2 >>= con;  // *signed* shift downward (high-order zeroes do not help)
1283       Node *newshr = phase->transform( new (phase->C) URShiftLNode(andi->in(1), in(2)) );
1284       return new (phase->C) AndLNode(newshr, phase->longcon(mask2));
1285     }
1286   }
1287 
1288   // Check for "(X << z ) >>> z" which simply zero-extends
1289   Node *shl = in(1);
1290   if( shl->Opcode() == Op_LShiftL &&
1291       phase->type(shl->in(2)) == t2 )
1292     return new (phase->C) AndLNode( shl->in(1), phase->longcon(mask) );
1293 
1294   return NULL;
1295 }
1296 
1297 //------------------------------Value------------------------------------------
1298 // A URShiftINode shifts its input2 right by input1 amount.
1299 const Type *URShiftLNode::Value( PhaseTransform *phase ) const {
1300   // (This is a near clone of RShiftLNode::Value.)
1301   const Type *t1 = phase->type( in(1) );
1302   const Type *t2 = phase->type( in(2) );
1303   // Either input is TOP ==> the result is TOP
1304   if( t1 == Type::TOP ) return Type::TOP;
1305   if( t2 == Type::TOP ) return Type::TOP;
1306 
1307   // Left input is ZERO ==> the result is ZERO.
1308   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
1309   // Shift by zero does nothing
1310   if( t2 == TypeInt::ZERO ) return t1;
1311 
1312   // Either input is BOTTOM ==> the result is BOTTOM
1313   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1314     return TypeLong::LONG;
1315 
1316   if (t2 == TypeInt::INT)
1317     return TypeLong::LONG;
1318 
1319   const TypeLong *r1 = t1->is_long(); // Handy access
1320   const TypeInt  *r2 = t2->is_int (); // Handy access
1321 
1322   if (r2->is_con()) {
1323     uint shift = r2->get_con();
1324     shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
1325     // Shift by a multiple of 64 does nothing:
1326     if (shift == 0)  return t1;
1327     // Calculate reasonably aggressive bounds for the result.
1328     jlong lo = (julong)r1->_lo >> (juint)shift;
1329     jlong hi = (julong)r1->_hi >> (juint)shift;
1330     if (r1->_hi >= 0 && r1->_lo < 0) {
1331       // If the type has both negative and positive values,
1332       // there are two separate sub-domains to worry about:
1333       // The positive half and the negative half.
1334       jlong neg_lo = lo;
1335       jlong neg_hi = (julong)-1 >> (juint)shift;
1336       jlong pos_lo = (julong) 0 >> (juint)shift;
1337       jlong pos_hi = hi;
1338       //lo = MIN2(neg_lo, pos_lo);  // == 0
1339       lo = neg_lo < pos_lo ? neg_lo : pos_lo;
1340       //hi = MAX2(neg_hi, pos_hi);  // == -1 >>> shift;
1341       hi = neg_hi > pos_hi ? neg_hi : pos_hi;
1342     }
1343     assert(lo <= hi, "must have valid bounds");
1344     const TypeLong* tl = TypeLong::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1345     #ifdef ASSERT
1346     // Make sure we get the sign-capture idiom correct.
1347     if (shift == BitsPerJavaLong - 1) {
1348       if (r1->_lo >= 0) assert(tl == TypeLong::ZERO, ">>>63 of + is 0");
1349       if (r1->_hi < 0)  assert(tl == TypeLong::ONE,  ">>>63 of - is +1");
1350     }
1351     #endif
1352     return tl;
1353   }
1354 
1355   return TypeLong::LONG;                // Give up
1356 }