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 = lo0*lo1;
 248   if( (double)A != a*c ) return TypeInt::INT; // Overflow?
 249   int32 B = lo0*hi1;
 250   if( (double)B != a*d ) return TypeInt::INT; // Overflow?
 251   int32 C = hi0*lo1;
 252   if( (double)C != b*c ) return TypeInt::INT; // Overflow?
 253   int32 D = 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 = lo0*lo1;
 344   if( (double)A != a*c ) return TypeLong::LONG; // Overflow?
 345   jlong B = lo0*hi1;
 346   if( (double)B != a*d ) return TypeLong::LONG; // Overflow?
 347   jlong C = hi0*lo1;
 348   if( (double)C != b*c ) return TypeLong::LONG; // Overflow?
 349   jlong D = 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       ldus = phase->transform(ldus);
 490       return new (phase->C) AndINode(ldus, phase->intcon(mask & 0xFFFF));
 491     }
 492 
 493     // Masking sign bits off of a Byte?  Do an unsigned byte load plus
 494     // an and.
 495     if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
 496       Node* ldub = new (phase->C) LoadUBNode(load->in(MemNode::Control),
 497                                              load->in(MemNode::Memory),
 498                                              load->in(MemNode::Address),
 499                                              load->adr_type());
 500       ldub = phase->transform(ldub);
 501       return new (phase->C) AndINode(ldub, phase->intcon(mask));
 502     }
 503   }
 504 
 505   // Masking off sign bits?  Dont make them!
 506   if( lop == Op_RShiftI ) {
 507     const TypeInt *t12 = phase->type(load->in(2))->isa_int();
 508     if( t12 && t12->is_con() ) { // Shift is by a constant
 509       int shift = t12->get_con();
 510       shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 511       const int sign_bits_mask = ~right_n_bits(BitsPerJavaInteger - shift);
 512       // If the AND'ing of the 2 masks has no bits, then only original shifted
 513       // bits survive.  NO sign-extension bits survive the maskings.
 514       if( (sign_bits_mask & mask) == 0 ) {
 515         // Use zero-fill shift instead
 516         Node *zshift = phase->transform(new (phase->C) URShiftINode(load->in(1),load->in(2)));
 517         return new (phase->C) AndINode( zshift, in(2) );
 518       }
 519     }
 520   }
 521 
 522   // Check for 'negate/and-1', a pattern emitted when someone asks for
 523   // 'mod 2'.  Negate leaves the low order bit unchanged (think: complement
 524   // plus 1) and the mask is of the low order bit.  Skip the negate.
 525   if( lop == Op_SubI && mask == 1 && load->in(1) &&
 526       phase->type(load->in(1)) == TypeInt::ZERO )
 527     return new (phase->C) AndINode( load->in(2), in(2) );
 528 
 529   return MulNode::Ideal(phase, can_reshape);
 530 }
 531 
 532 //=============================================================================
 533 //------------------------------mul_ring---------------------------------------
 534 // Supplied function returns the product of the inputs IN THE CURRENT RING.
 535 // For the logical operations the ring's MUL is really a logical AND function.
 536 // This also type-checks the inputs for sanity.  Guaranteed never to
 537 // be passed a TOP or BOTTOM type, these are filtered out by pre-check.
 538 const Type *AndLNode::mul_ring( const Type *t0, const Type *t1 ) const {
 539   const TypeLong *r0 = t0->is_long(); // Handy access
 540   const TypeLong *r1 = t1->is_long();
 541   int widen = MAX2(r0->_widen,r1->_widen);
 542 
 543   // If either input is a constant, might be able to trim cases
 544   if( !r0->is_con() && !r1->is_con() )
 545     return TypeLong::LONG;      // No constants to be had
 546 
 547   // Both constants?  Return bits
 548   if( r0->is_con() && r1->is_con() )
 549     return TypeLong::make( r0->get_con() & r1->get_con() );
 550 
 551   if( r0->is_con() && r0->get_con() > 0 )
 552     return TypeLong::make(CONST64(0), r0->get_con(), widen);
 553 
 554   if( r1->is_con() && r1->get_con() > 0 )
 555     return TypeLong::make(CONST64(0), r1->get_con(), widen);
 556 
 557   return TypeLong::LONG;        // No constants to be had
 558 }
 559 
 560 //------------------------------Identity---------------------------------------
 561 // Masking off the high bits of an unsigned load is not required
 562 Node *AndLNode::Identity( PhaseTransform *phase ) {
 563 
 564   // x & x => x
 565   if (phase->eqv(in(1), in(2))) return in(1);
 566 
 567   Node *usr = in(1);
 568   const TypeLong *t2 = phase->type( in(2) )->isa_long();
 569   if( t2 && t2->is_con() ) {
 570     jlong con = t2->get_con();
 571     // Masking off high bits which are always zero is useless.
 572     const TypeLong* t1 = phase->type( in(1) )->isa_long();
 573     if (t1 != NULL && t1->_lo >= 0) {
 574       jlong t1_support = ((jlong)1 << (1 + log2_long(t1->_hi))) - 1;
 575       if ((t1_support & con) == t1_support)
 576         return usr;
 577     }
 578     uint lop = usr->Opcode();
 579     // Masking off the high bits of a unsigned-shift-right is not
 580     // needed either.
 581     if( lop == Op_URShiftL ) {
 582       const TypeInt *t12 = phase->type( usr->in(2) )->isa_int();
 583       if( t12 && t12->is_con() ) {  // Shift is by a constant
 584         int shift = t12->get_con();
 585         shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 586         jlong mask = max_julong >> shift;
 587         if( (mask&con) == mask )  // If AND is useless, skip it
 588           return usr;
 589       }
 590     }
 591   }
 592   return MulNode::Identity(phase);
 593 }
 594 
 595 //------------------------------Ideal------------------------------------------
 596 Node *AndLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 597   // Special case constant AND mask
 598   const TypeLong *t2 = phase->type( in(2) )->isa_long();
 599   if( !t2 || !t2->is_con() ) return MulNode::Ideal(phase, can_reshape);
 600   const jlong mask = t2->get_con();
 601 
 602   Node* in1 = in(1);
 603   uint op = in1->Opcode();
 604 
 605   // Are we masking a long that was converted from an int with a mask
 606   // that fits in 32-bits?  Commute them and use an AndINode.  Don't
 607   // convert masks which would cause a sign extension of the integer
 608   // value.  This check includes UI2L masks (0x00000000FFFFFFFF) which
 609   // would be optimized away later in Identity.
 610   if (op == Op_ConvI2L && (mask & CONST64(0xFFFFFFFF80000000)) == 0) {
 611     Node* andi = new (phase->C) AndINode(in1->in(1), phase->intcon(mask));
 612     andi = phase->transform(andi);
 613     return new (phase->C) ConvI2LNode(andi);
 614   }
 615 
 616   // Masking off sign bits?  Dont make them!
 617   if (op == Op_RShiftL) {
 618     const TypeInt* t12 = phase->type(in1->in(2))->isa_int();
 619     if( t12 && t12->is_con() ) { // Shift is by a constant
 620       int shift = t12->get_con();
 621       shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 622       const jlong sign_bits_mask = ~(((jlong)CONST64(1) << (jlong)(BitsPerJavaLong - shift)) -1);
 623       // If the AND'ing of the 2 masks has no bits, then only original shifted
 624       // bits survive.  NO sign-extension bits survive the maskings.
 625       if( (sign_bits_mask & mask) == 0 ) {
 626         // Use zero-fill shift instead
 627         Node *zshift = phase->transform(new (phase->C) URShiftLNode(in1->in(1), in1->in(2)));
 628         return new (phase->C) AndLNode(zshift, in(2));
 629       }
 630     }
 631   }
 632 
 633   return MulNode::Ideal(phase, can_reshape);
 634 }
 635 
 636 //=============================================================================
 637 //------------------------------Identity---------------------------------------
 638 Node *LShiftINode::Identity( PhaseTransform *phase ) {
 639   const TypeInt *ti = phase->type( in(2) )->isa_int();  // shift count is an int
 640   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerInt - 1 ) ) == 0 ) ? in(1) : this;
 641 }
 642 
 643 //------------------------------Ideal------------------------------------------
 644 // If the right input is a constant, and the left input is an add of a
 645 // constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
 646 Node *LShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 647   const Type *t  = phase->type( in(2) );
 648   if( t == Type::TOP ) return NULL;       // Right input is dead
 649   const TypeInt *t2 = t->isa_int();
 650   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 651   const int con = t2->get_con() & ( BitsPerInt - 1 );  // masked shift count
 652 
 653   if ( con == 0 )  return NULL; // let Identity() handle 0 shift count
 654 
 655   // Left input is an add of a constant?
 656   Node *add1 = in(1);
 657   int add1_op = add1->Opcode();
 658   if( add1_op == Op_AddI ) {    // Left input is an add?
 659     assert( add1 != add1->in(1), "dead loop in LShiftINode::Ideal" );
 660     const TypeInt *t12 = phase->type(add1->in(2))->isa_int();
 661     if( t12 && t12->is_con() ){ // Left input is an add of a con?
 662       // Transform is legal, but check for profit.  Avoid breaking 'i2s'
 663       // and 'i2b' patterns which typically fold into 'StoreC/StoreB'.
 664       if( con < 16 ) {
 665         // Compute X << con0
 666         Node *lsh = phase->transform( new (phase->C) LShiftINode( add1->in(1), in(2) ) );
 667         // Compute X<<con0 + (con1<<con0)
 668         return new (phase->C) AddINode( lsh, phase->intcon(t12->get_con() << con));
 669       }
 670     }
 671   }
 672 
 673   // Check for "(x>>c0)<<c0" which just masks off low bits
 674   if( (add1_op == Op_RShiftI || add1_op == Op_URShiftI ) &&
 675       add1->in(2) == in(2) )
 676     // Convert to "(x & -(1<<c0))"
 677     return new (phase->C) AndINode(add1->in(1),phase->intcon( -(1<<con)));
 678 
 679   // Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
 680   if( add1_op == Op_AndI ) {
 681     Node *add2 = add1->in(1);
 682     int add2_op = add2->Opcode();
 683     if( (add2_op == Op_RShiftI || add2_op == Op_URShiftI ) &&
 684         add2->in(2) == in(2) ) {
 685       // Convert to "(x & (Y<<c0))"
 686       Node *y_sh = phase->transform( new (phase->C) LShiftINode( add1->in(2), in(2) ) );
 687       return new (phase->C) AndINode( add2->in(1), y_sh );
 688     }
 689   }
 690 
 691   // Check for ((x & ((1<<(32-c0))-1)) << c0) which ANDs off high bits
 692   // before shifting them away.
 693   const jint bits_mask = right_n_bits(BitsPerJavaInteger-con);
 694   if( add1_op == Op_AndI &&
 695       phase->type(add1->in(2)) == TypeInt::make( bits_mask ) )
 696     return new (phase->C) LShiftINode( add1->in(1), in(2) );
 697 
 698   return NULL;
 699 }
 700 
 701 //------------------------------Value------------------------------------------
 702 // A LShiftINode shifts its input2 left by input1 amount.
 703 const Type *LShiftINode::Value( PhaseTransform *phase ) const {
 704   const Type *t1 = phase->type( in(1) );
 705   const Type *t2 = phase->type( in(2) );
 706   // Either input is TOP ==> the result is TOP
 707   if( t1 == Type::TOP ) return Type::TOP;
 708   if( t2 == Type::TOP ) return Type::TOP;
 709 
 710   // Left input is ZERO ==> the result is ZERO.
 711   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
 712   // Shift by zero does nothing
 713   if( t2 == TypeInt::ZERO ) return t1;
 714 
 715   // Either input is BOTTOM ==> the result is BOTTOM
 716   if( (t1 == TypeInt::INT) || (t2 == TypeInt::INT) ||
 717       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 718     return TypeInt::INT;
 719 
 720   const TypeInt *r1 = t1->is_int(); // Handy access
 721   const TypeInt *r2 = t2->is_int(); // Handy access
 722 
 723   if (!r2->is_con())
 724     return TypeInt::INT;
 725 
 726   uint shift = r2->get_con();
 727   shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 728   // Shift by a multiple of 32 does nothing:
 729   if (shift == 0)  return t1;
 730 
 731   // If the shift is a constant, shift the bounds of the type,
 732   // unless this could lead to an overflow.
 733   if (!r1->is_con()) {
 734     jint lo = r1->_lo, hi = r1->_hi;
 735     if (((lo << shift) >> shift) == lo &&
 736         ((hi << shift) >> shift) == hi) {
 737       // No overflow.  The range shifts up cleanly.
 738       return TypeInt::make((jint)lo << (jint)shift,
 739                            (jint)hi << (jint)shift,
 740                            MAX2(r1->_widen,r2->_widen));
 741     }
 742     return TypeInt::INT;
 743   }
 744 
 745   return TypeInt::make( (jint)r1->get_con() << (jint)shift );
 746 }
 747 
 748 //=============================================================================
 749 //------------------------------Identity---------------------------------------
 750 Node *LShiftLNode::Identity( PhaseTransform *phase ) {
 751   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
 752   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
 753 }
 754 
 755 //------------------------------Ideal------------------------------------------
 756 // If the right input is a constant, and the left input is an add of a
 757 // constant, flatten the tree: (X+con1)<<con0 ==> X<<con0 + con1<<con0
 758 Node *LShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 759   const Type *t  = phase->type( in(2) );
 760   if( t == Type::TOP ) return NULL;       // Right input is dead
 761   const TypeInt *t2 = t->isa_int();
 762   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 763   const int con = t2->get_con() & ( BitsPerLong - 1 );  // masked shift count
 764 
 765   if ( con == 0 ) return NULL;  // let Identity() handle 0 shift count
 766 
 767   // Left input is an add of a constant?
 768   Node *add1 = in(1);
 769   int add1_op = add1->Opcode();
 770   if( add1_op == Op_AddL ) {    // Left input is an add?
 771     // Avoid dead data cycles from dead loops
 772     assert( add1 != add1->in(1), "dead loop in LShiftLNode::Ideal" );
 773     const TypeLong *t12 = phase->type(add1->in(2))->isa_long();
 774     if( t12 && t12->is_con() ){ // Left input is an add of a con?
 775       // Compute X << con0
 776       Node *lsh = phase->transform( new (phase->C) LShiftLNode( add1->in(1), in(2) ) );
 777       // Compute X<<con0 + (con1<<con0)
 778       return new (phase->C) AddLNode( lsh, phase->longcon(t12->get_con() << con));
 779     }
 780   }
 781 
 782   // Check for "(x>>c0)<<c0" which just masks off low bits
 783   if( (add1_op == Op_RShiftL || add1_op == Op_URShiftL ) &&
 784       add1->in(2) == in(2) )
 785     // Convert to "(x & -(1<<c0))"
 786     return new (phase->C) AndLNode(add1->in(1),phase->longcon( -(CONST64(1)<<con)));
 787 
 788   // Check for "((x>>c0) & Y)<<c0" which just masks off more low bits
 789   if( add1_op == Op_AndL ) {
 790     Node *add2 = add1->in(1);
 791     int add2_op = add2->Opcode();
 792     if( (add2_op == Op_RShiftL || add2_op == Op_URShiftL ) &&
 793         add2->in(2) == in(2) ) {
 794       // Convert to "(x & (Y<<c0))"
 795       Node *y_sh = phase->transform( new (phase->C) LShiftLNode( add1->in(2), in(2) ) );
 796       return new (phase->C) AndLNode( add2->in(1), y_sh );
 797     }
 798   }
 799 
 800   // Check for ((x & ((CONST64(1)<<(64-c0))-1)) << c0) which ANDs off high bits
 801   // before shifting them away.
 802   const jlong bits_mask = ((jlong)CONST64(1) << (jlong)(BitsPerJavaLong - con)) - CONST64(1);
 803   if( add1_op == Op_AndL &&
 804       phase->type(add1->in(2)) == TypeLong::make( bits_mask ) )
 805     return new (phase->C) LShiftLNode( add1->in(1), in(2) );
 806 
 807   return NULL;
 808 }
 809 
 810 //------------------------------Value------------------------------------------
 811 // A LShiftLNode shifts its input2 left by input1 amount.
 812 const Type *LShiftLNode::Value( PhaseTransform *phase ) const {
 813   const Type *t1 = phase->type( in(1) );
 814   const Type *t2 = phase->type( in(2) );
 815   // Either input is TOP ==> the result is TOP
 816   if( t1 == Type::TOP ) return Type::TOP;
 817   if( t2 == Type::TOP ) return Type::TOP;
 818 
 819   // Left input is ZERO ==> the result is ZERO.
 820   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
 821   // Shift by zero does nothing
 822   if( t2 == TypeInt::ZERO ) return t1;
 823 
 824   // Either input is BOTTOM ==> the result is BOTTOM
 825   if( (t1 == TypeLong::LONG) || (t2 == TypeInt::INT) ||
 826       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 827     return TypeLong::LONG;
 828 
 829   const TypeLong *r1 = t1->is_long(); // Handy access
 830   const TypeInt  *r2 = t2->is_int();  // Handy access
 831 
 832   if (!r2->is_con())
 833     return TypeLong::LONG;
 834 
 835   uint shift = r2->get_con();
 836   shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
 837   // Shift by a multiple of 64 does nothing:
 838   if (shift == 0)  return t1;
 839 
 840   // If the shift is a constant, shift the bounds of the type,
 841   // unless this could lead to an overflow.
 842   if (!r1->is_con()) {
 843     jlong lo = r1->_lo, hi = r1->_hi;
 844     if (((lo << shift) >> shift) == lo &&
 845         ((hi << shift) >> shift) == hi) {
 846       // No overflow.  The range shifts up cleanly.
 847       return TypeLong::make((jlong)lo << (jint)shift,
 848                             (jlong)hi << (jint)shift,
 849                             MAX2(r1->_widen,r2->_widen));
 850     }
 851     return TypeLong::LONG;
 852   }
 853 
 854   return TypeLong::make( (jlong)r1->get_con() << (jint)shift );
 855 }
 856 
 857 //=============================================================================
 858 //------------------------------Identity---------------------------------------
 859 Node *RShiftINode::Identity( PhaseTransform *phase ) {
 860   const TypeInt *t2 = phase->type(in(2))->isa_int();
 861   if( !t2 ) return this;
 862   if ( t2->is_con() && ( t2->get_con() & ( BitsPerInt - 1 ) ) == 0 )
 863     return in(1);
 864 
 865   // Check for useless sign-masking
 866   if( in(1)->Opcode() == Op_LShiftI &&
 867       in(1)->req() == 3 &&
 868       in(1)->in(2) == in(2) &&
 869       t2->is_con() ) {
 870     uint shift = t2->get_con();
 871     shift &= BitsPerJavaInteger-1; // semantics of Java shifts
 872     // Compute masks for which this shifting doesn't change
 873     int lo = (-1 << (BitsPerJavaInteger - shift-1)); // FFFF8000
 874     int hi = ~lo;               // 00007FFF
 875     const TypeInt *t11 = phase->type(in(1)->in(1))->isa_int();
 876     if( !t11 ) return this;
 877     // Does actual value fit inside of mask?
 878     if( lo <= t11->_lo && t11->_hi <= hi )
 879       return in(1)->in(1);      // Then shifting is a nop
 880   }
 881 
 882   return this;
 883 }
 884 
 885 //------------------------------Ideal------------------------------------------
 886 Node *RShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
 887   // Inputs may be TOP if they are dead.
 888   const TypeInt *t1 = phase->type( in(1) )->isa_int();
 889   if( !t1 ) return NULL;        // Left input is an integer
 890   const TypeInt *t2 = phase->type( in(2) )->isa_int();
 891   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
 892   const TypeInt *t3;  // type of in(1).in(2)
 893   int shift = t2->get_con();
 894   shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 895 
 896   if ( shift == 0 ) return NULL;  // let Identity() handle 0 shift count
 897 
 898   // Check for (x & 0xFF000000) >> 24, whose mask can be made smaller.
 899   // Such expressions arise normally from shift chains like (byte)(x >> 24).
 900   const Node *mask = in(1);
 901   if( mask->Opcode() == Op_AndI &&
 902       (t3 = phase->type(mask->in(2))->isa_int()) &&
 903       t3->is_con() ) {
 904     Node *x = mask->in(1);
 905     jint maskbits = t3->get_con();
 906     // Convert to "(x >> shift) & (mask >> shift)"
 907     Node *shr_nomask = phase->transform( new (phase->C) RShiftINode(mask->in(1), in(2)) );
 908     return new (phase->C) AndINode(shr_nomask, phase->intcon( maskbits >> shift));
 909   }
 910 
 911   // Check for "(short[i] <<16)>>16" which simply sign-extends
 912   const Node *shl = in(1);
 913   if( shl->Opcode() != Op_LShiftI ) return NULL;
 914 
 915   if( shift == 16 &&
 916       (t3 = phase->type(shl->in(2))->isa_int()) &&
 917       t3->is_con(16) ) {
 918     Node *ld = shl->in(1);
 919     if( ld->Opcode() == Op_LoadS ) {
 920       // Sign extension is just useless here.  Return a RShiftI of zero instead
 921       // returning 'ld' directly.  We cannot return an old Node directly as
 922       // that is the job of 'Identity' calls and Identity calls only work on
 923       // direct inputs ('ld' is an extra Node removed from 'this').  The
 924       // combined optimization requires Identity only return direct inputs.
 925       set_req(1, ld);
 926       set_req(2, phase->intcon(0));
 927       return this;
 928     }
 929     else if( can_reshape &&
 930              ld->Opcode() == Op_LoadUS &&
 931              ld->outcnt() == 1 && ld->unique_out() == shl)
 932       // Replace zero-extension-load with sign-extension-load
 933       return new (phase->C) LoadSNode( ld->in(MemNode::Control),
 934                                 ld->in(MemNode::Memory),
 935                                 ld->in(MemNode::Address),
 936                                 ld->adr_type());
 937   }
 938 
 939   // Check for "(byte[i] <<24)>>24" which simply sign-extends
 940   if( shift == 24 &&
 941       (t3 = phase->type(shl->in(2))->isa_int()) &&
 942       t3->is_con(24) ) {
 943     Node *ld = shl->in(1);
 944     if( ld->Opcode() == Op_LoadB ) {
 945       // Sign extension is just useless here
 946       set_req(1, ld);
 947       set_req(2, phase->intcon(0));
 948       return this;
 949     }
 950   }
 951 
 952   return NULL;
 953 }
 954 
 955 //------------------------------Value------------------------------------------
 956 // A RShiftINode shifts its input2 right by input1 amount.
 957 const Type *RShiftINode::Value( PhaseTransform *phase ) const {
 958   const Type *t1 = phase->type( in(1) );
 959   const Type *t2 = phase->type( in(2) );
 960   // Either input is TOP ==> the result is TOP
 961   if( t1 == Type::TOP ) return Type::TOP;
 962   if( t2 == Type::TOP ) return Type::TOP;
 963 
 964   // Left input is ZERO ==> the result is ZERO.
 965   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
 966   // Shift by zero does nothing
 967   if( t2 == TypeInt::ZERO ) return t1;
 968 
 969   // Either input is BOTTOM ==> the result is BOTTOM
 970   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
 971     return TypeInt::INT;
 972 
 973   if (t2 == TypeInt::INT)
 974     return TypeInt::INT;
 975 
 976   const TypeInt *r1 = t1->is_int(); // Handy access
 977   const TypeInt *r2 = t2->is_int(); // Handy access
 978 
 979   // If the shift is a constant, just shift the bounds of the type.
 980   // For example, if the shift is 31, we just propagate sign bits.
 981   if (r2->is_con()) {
 982     uint shift = r2->get_con();
 983     shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
 984     // Shift by a multiple of 32 does nothing:
 985     if (shift == 0)  return t1;
 986     // Calculate reasonably aggressive bounds for the result.
 987     // This is necessary if we are to correctly type things
 988     // like (x<<24>>24) == ((byte)x).
 989     jint lo = (jint)r1->_lo >> (jint)shift;
 990     jint hi = (jint)r1->_hi >> (jint)shift;
 991     assert(lo <= hi, "must have valid bounds");
 992     const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
 993 #ifdef ASSERT
 994     // Make sure we get the sign-capture idiom correct.
 995     if (shift == BitsPerJavaInteger-1) {
 996       if (r1->_lo >= 0) assert(ti == TypeInt::ZERO,    ">>31 of + is  0");
 997       if (r1->_hi <  0) assert(ti == TypeInt::MINUS_1, ">>31 of - is -1");
 998     }
 999 #endif
1000     return ti;
1001   }
1002 
1003   if( !r1->is_con() || !r2->is_con() )
1004     return TypeInt::INT;
1005 
1006   // Signed shift right
1007   return TypeInt::make( r1->get_con() >> (r2->get_con()&31) );
1008 }
1009 
1010 //=============================================================================
1011 //------------------------------Identity---------------------------------------
1012 Node *RShiftLNode::Identity( PhaseTransform *phase ) {
1013   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
1014   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
1015 }
1016 
1017 //------------------------------Value------------------------------------------
1018 // A RShiftLNode shifts its input2 right by input1 amount.
1019 const Type *RShiftLNode::Value( PhaseTransform *phase ) const {
1020   const Type *t1 = phase->type( in(1) );
1021   const Type *t2 = phase->type( in(2) );
1022   // Either input is TOP ==> the result is TOP
1023   if( t1 == Type::TOP ) return Type::TOP;
1024   if( t2 == Type::TOP ) return Type::TOP;
1025 
1026   // Left input is ZERO ==> the result is ZERO.
1027   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
1028   // Shift by zero does nothing
1029   if( t2 == TypeInt::ZERO ) return t1;
1030 
1031   // Either input is BOTTOM ==> the result is BOTTOM
1032   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1033     return TypeLong::LONG;
1034 
1035   if (t2 == TypeInt::INT)
1036     return TypeLong::LONG;
1037 
1038   const TypeLong *r1 = t1->is_long(); // Handy access
1039   const TypeInt  *r2 = t2->is_int (); // Handy access
1040 
1041   // If the shift is a constant, just shift the bounds of the type.
1042   // For example, if the shift is 63, we just propagate sign bits.
1043   if (r2->is_con()) {
1044     uint shift = r2->get_con();
1045     shift &= (2*BitsPerJavaInteger)-1;  // semantics of Java shifts
1046     // Shift by a multiple of 64 does nothing:
1047     if (shift == 0)  return t1;
1048     // Calculate reasonably aggressive bounds for the result.
1049     // This is necessary if we are to correctly type things
1050     // like (x<<24>>24) == ((byte)x).
1051     jlong lo = (jlong)r1->_lo >> (jlong)shift;
1052     jlong hi = (jlong)r1->_hi >> (jlong)shift;
1053     assert(lo <= hi, "must have valid bounds");
1054     const TypeLong* tl = TypeLong::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1055     #ifdef ASSERT
1056     // Make sure we get the sign-capture idiom correct.
1057     if (shift == (2*BitsPerJavaInteger)-1) {
1058       if (r1->_lo >= 0) assert(tl == TypeLong::ZERO,    ">>63 of + is 0");
1059       if (r1->_hi < 0)  assert(tl == TypeLong::MINUS_1, ">>63 of - is -1");
1060     }
1061     #endif
1062     return tl;
1063   }
1064 
1065   return TypeLong::LONG;                // Give up
1066 }
1067 
1068 //=============================================================================
1069 //------------------------------Identity---------------------------------------
1070 Node *URShiftINode::Identity( PhaseTransform *phase ) {
1071   const TypeInt *ti = phase->type( in(2) )->isa_int();
1072   if ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerInt - 1 ) ) == 0 ) return in(1);
1073 
1074   // Check for "((x << LogBytesPerWord) + (wordSize-1)) >> LogBytesPerWord" which is just "x".
1075   // Happens during new-array length computation.
1076   // Safe if 'x' is in the range [0..(max_int>>LogBytesPerWord)]
1077   Node *add = in(1);
1078   if( add->Opcode() == Op_AddI ) {
1079     const TypeInt *t2  = phase->type(add->in(2))->isa_int();
1080     if( t2 && t2->is_con(wordSize - 1) &&
1081         add->in(1)->Opcode() == Op_LShiftI ) {
1082       // Check that shift_counts are LogBytesPerWord
1083       Node          *lshift_count   = add->in(1)->in(2);
1084       const TypeInt *t_lshift_count = phase->type(lshift_count)->isa_int();
1085       if( t_lshift_count && t_lshift_count->is_con(LogBytesPerWord) &&
1086           t_lshift_count == phase->type(in(2)) ) {
1087         Node          *x   = add->in(1)->in(1);
1088         const TypeInt *t_x = phase->type(x)->isa_int();
1089         if( t_x != NULL && 0 <= t_x->_lo && t_x->_hi <= (max_jint>>LogBytesPerWord) ) {
1090           return x;
1091         }
1092       }
1093     }
1094   }
1095 
1096   return (phase->type(in(2))->higher_equal(TypeInt::ZERO)) ? in(1) : this;
1097 }
1098 
1099 //------------------------------Ideal------------------------------------------
1100 Node *URShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
1101   const TypeInt *t2 = phase->type( in(2) )->isa_int();
1102   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
1103   const int con = t2->get_con() & 31; // Shift count is always masked
1104   if ( con == 0 ) return NULL;  // let Identity() handle a 0 shift count
1105   // We'll be wanting the right-shift amount as a mask of that many bits
1106   const int mask = right_n_bits(BitsPerJavaInteger - con);
1107 
1108   int in1_op = in(1)->Opcode();
1109 
1110   // Check for ((x>>>a)>>>b) and replace with (x>>>(a+b)) when a+b < 32
1111   if( in1_op == Op_URShiftI ) {
1112     const TypeInt *t12 = phase->type( in(1)->in(2) )->isa_int();
1113     if( t12 && t12->is_con() ) { // Right input is a constant
1114       assert( in(1) != in(1)->in(1), "dead loop in URShiftINode::Ideal" );
1115       const int con2 = t12->get_con() & 31; // Shift count is always masked
1116       const int con3 = con+con2;
1117       if( con3 < 32 )           // Only merge shifts if total is < 32
1118         return new (phase->C) URShiftINode( in(1)->in(1), phase->intcon(con3) );
1119     }
1120   }
1121 
1122   // Check for ((x << z) + Y) >>> z.  Replace with x + con>>>z
1123   // The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
1124   // If Q is "X << z" the rounding is useless.  Look for patterns like
1125   // ((X<<Z) + Y) >>> Z  and replace with (X + Y>>>Z) & Z-mask.
1126   Node *add = in(1);
1127   if( in1_op == Op_AddI ) {
1128     Node *lshl = add->in(1);
1129     if( lshl->Opcode() == Op_LShiftI &&
1130         phase->type(lshl->in(2)) == t2 ) {
1131       Node *y_z = phase->transform( new (phase->C) URShiftINode(add->in(2),in(2)) );
1132       Node *sum = phase->transform( new (phase->C) AddINode( lshl->in(1), y_z ) );
1133       return new (phase->C) AndINode( sum, phase->intcon(mask) );
1134     }
1135   }
1136 
1137   // Check for (x & mask) >>> z.  Replace with (x >>> z) & (mask >>> z)
1138   // This shortens the mask.  Also, if we are extracting a high byte and
1139   // storing it to a buffer, the mask will be removed completely.
1140   Node *andi = in(1);
1141   if( in1_op == Op_AndI ) {
1142     const TypeInt *t3 = phase->type( andi->in(2) )->isa_int();
1143     if( t3 && t3->is_con() ) { // Right input is a constant
1144       jint mask2 = t3->get_con();
1145       mask2 >>= con;  // *signed* shift downward (high-order zeroes do not help)
1146       Node *newshr = phase->transform( new (phase->C) URShiftINode(andi->in(1), in(2)) );
1147       return new (phase->C) AndINode(newshr, phase->intcon(mask2));
1148       // The negative values are easier to materialize than positive ones.
1149       // A typical case from address arithmetic is ((x & ~15) >> 4).
1150       // It's better to change that to ((x >> 4) & ~0) versus
1151       // ((x >> 4) & 0x0FFFFFFF).  The difference is greatest in LP64.
1152     }
1153   }
1154 
1155   // Check for "(X << z ) >>> z" which simply zero-extends
1156   Node *shl = in(1);
1157   if( in1_op == Op_LShiftI &&
1158       phase->type(shl->in(2)) == t2 )
1159     return new (phase->C) AndINode( shl->in(1), phase->intcon(mask) );
1160 
1161   return NULL;
1162 }
1163 
1164 //------------------------------Value------------------------------------------
1165 // A URShiftINode shifts its input2 right by input1 amount.
1166 const Type *URShiftINode::Value( PhaseTransform *phase ) const {
1167   // (This is a near clone of RShiftINode::Value.)
1168   const Type *t1 = phase->type( in(1) );
1169   const Type *t2 = phase->type( in(2) );
1170   // Either input is TOP ==> the result is TOP
1171   if( t1 == Type::TOP ) return Type::TOP;
1172   if( t2 == Type::TOP ) return Type::TOP;
1173 
1174   // Left input is ZERO ==> the result is ZERO.
1175   if( t1 == TypeInt::ZERO ) return TypeInt::ZERO;
1176   // Shift by zero does nothing
1177   if( t2 == TypeInt::ZERO ) return t1;
1178 
1179   // Either input is BOTTOM ==> the result is BOTTOM
1180   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1181     return TypeInt::INT;
1182 
1183   if (t2 == TypeInt::INT)
1184     return TypeInt::INT;
1185 
1186   const TypeInt *r1 = t1->is_int();     // Handy access
1187   const TypeInt *r2 = t2->is_int();     // Handy access
1188 
1189   if (r2->is_con()) {
1190     uint shift = r2->get_con();
1191     shift &= BitsPerJavaInteger-1;  // semantics of Java shifts
1192     // Shift by a multiple of 32 does nothing:
1193     if (shift == 0)  return t1;
1194     // Calculate reasonably aggressive bounds for the result.
1195     jint lo = (juint)r1->_lo >> (juint)shift;
1196     jint hi = (juint)r1->_hi >> (juint)shift;
1197     if (r1->_hi >= 0 && r1->_lo < 0) {
1198       // If the type has both negative and positive values,
1199       // there are two separate sub-domains to worry about:
1200       // The positive half and the negative half.
1201       jint neg_lo = lo;
1202       jint neg_hi = (juint)-1 >> (juint)shift;
1203       jint pos_lo = (juint) 0 >> (juint)shift;
1204       jint pos_hi = hi;
1205       lo = MIN2(neg_lo, pos_lo);  // == 0
1206       hi = MAX2(neg_hi, pos_hi);  // == -1 >>> shift;
1207     }
1208     assert(lo <= hi, "must have valid bounds");
1209     const TypeInt* ti = TypeInt::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1210     #ifdef ASSERT
1211     // Make sure we get the sign-capture idiom correct.
1212     if (shift == BitsPerJavaInteger-1) {
1213       if (r1->_lo >= 0) assert(ti == TypeInt::ZERO, ">>>31 of + is 0");
1214       if (r1->_hi < 0)  assert(ti == TypeInt::ONE,  ">>>31 of - is +1");
1215     }
1216     #endif
1217     return ti;
1218   }
1219 
1220   //
1221   // Do not support shifted oops in info for GC
1222   //
1223   // else if( t1->base() == Type::InstPtr ) {
1224   //
1225   //   const TypeInstPtr *o = t1->is_instptr();
1226   //   if( t1->singleton() )
1227   //     return TypeInt::make( ((uint32)o->const_oop() + o->_offset) >> shift );
1228   // }
1229   // else if( t1->base() == Type::KlassPtr ) {
1230   //   const TypeKlassPtr *o = t1->is_klassptr();
1231   //   if( t1->singleton() )
1232   //     return TypeInt::make( ((uint32)o->const_oop() + o->_offset) >> shift );
1233   // }
1234 
1235   return TypeInt::INT;
1236 }
1237 
1238 //=============================================================================
1239 //------------------------------Identity---------------------------------------
1240 Node *URShiftLNode::Identity( PhaseTransform *phase ) {
1241   const TypeInt *ti = phase->type( in(2) )->isa_int(); // shift count is an int
1242   return ( ti && ti->is_con() && ( ti->get_con() & ( BitsPerLong - 1 ) ) == 0 ) ? in(1) : this;
1243 }
1244 
1245 //------------------------------Ideal------------------------------------------
1246 Node *URShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1247   const TypeInt *t2 = phase->type( in(2) )->isa_int();
1248   if( !t2 || !t2->is_con() ) return NULL; // Right input is a constant
1249   const int con = t2->get_con() & ( BitsPerLong - 1 ); // Shift count is always masked
1250   if ( con == 0 ) return NULL;  // let Identity() handle a 0 shift count
1251                               // note: mask computation below does not work for 0 shift count
1252   // We'll be wanting the right-shift amount as a mask of that many bits
1253   const jlong mask = (((jlong)CONST64(1) << (jlong)(BitsPerJavaLong - con)) -1);
1254 
1255   // Check for ((x << z) + Y) >>> z.  Replace with x + con>>>z
1256   // The idiom for rounding to a power of 2 is "(Q+(2^z-1)) >>> z".
1257   // If Q is "X << z" the rounding is useless.  Look for patterns like
1258   // ((X<<Z) + Y) >>> Z  and replace with (X + Y>>>Z) & Z-mask.
1259   Node *add = in(1);
1260   if( add->Opcode() == Op_AddL ) {
1261     Node *lshl = add->in(1);
1262     if( lshl->Opcode() == Op_LShiftL &&
1263         phase->type(lshl->in(2)) == t2 ) {
1264       Node *y_z = phase->transform( new (phase->C) URShiftLNode(add->in(2),in(2)) );
1265       Node *sum = phase->transform( new (phase->C) AddLNode( lshl->in(1), y_z ) );
1266       return new (phase->C) AndLNode( sum, phase->longcon(mask) );
1267     }
1268   }
1269 
1270   // Check for (x & mask) >>> z.  Replace with (x >>> z) & (mask >>> z)
1271   // This shortens the mask.  Also, if we are extracting a high byte and
1272   // storing it to a buffer, the mask will be removed completely.
1273   Node *andi = in(1);
1274   if( andi->Opcode() == Op_AndL ) {
1275     const TypeLong *t3 = phase->type( andi->in(2) )->isa_long();
1276     if( t3 && t3->is_con() ) { // Right input is a constant
1277       jlong mask2 = t3->get_con();
1278       mask2 >>= con;  // *signed* shift downward (high-order zeroes do not help)
1279       Node *newshr = phase->transform( new (phase->C) URShiftLNode(andi->in(1), in(2)) );
1280       return new (phase->C) AndLNode(newshr, phase->longcon(mask2));
1281     }
1282   }
1283 
1284   // Check for "(X << z ) >>> z" which simply zero-extends
1285   Node *shl = in(1);
1286   if( shl->Opcode() == Op_LShiftL &&
1287       phase->type(shl->in(2)) == t2 )
1288     return new (phase->C) AndLNode( shl->in(1), phase->longcon(mask) );
1289 
1290   return NULL;
1291 }
1292 
1293 //------------------------------Value------------------------------------------
1294 // A URShiftINode shifts its input2 right by input1 amount.
1295 const Type *URShiftLNode::Value( PhaseTransform *phase ) const {
1296   // (This is a near clone of RShiftLNode::Value.)
1297   const Type *t1 = phase->type( in(1) );
1298   const Type *t2 = phase->type( in(2) );
1299   // Either input is TOP ==> the result is TOP
1300   if( t1 == Type::TOP ) return Type::TOP;
1301   if( t2 == Type::TOP ) return Type::TOP;
1302 
1303   // Left input is ZERO ==> the result is ZERO.
1304   if( t1 == TypeLong::ZERO ) return TypeLong::ZERO;
1305   // Shift by zero does nothing
1306   if( t2 == TypeInt::ZERO ) return t1;
1307 
1308   // Either input is BOTTOM ==> the result is BOTTOM
1309   if (t1 == Type::BOTTOM || t2 == Type::BOTTOM)
1310     return TypeLong::LONG;
1311 
1312   if (t2 == TypeInt::INT)
1313     return TypeLong::LONG;
1314 
1315   const TypeLong *r1 = t1->is_long(); // Handy access
1316   const TypeInt  *r2 = t2->is_int (); // Handy access
1317 
1318   if (r2->is_con()) {
1319     uint shift = r2->get_con();
1320     shift &= BitsPerJavaLong - 1;  // semantics of Java shifts
1321     // Shift by a multiple of 64 does nothing:
1322     if (shift == 0)  return t1;
1323     // Calculate reasonably aggressive bounds for the result.
1324     jlong lo = (julong)r1->_lo >> (juint)shift;
1325     jlong hi = (julong)r1->_hi >> (juint)shift;
1326     if (r1->_hi >= 0 && r1->_lo < 0) {
1327       // If the type has both negative and positive values,
1328       // there are two separate sub-domains to worry about:
1329       // The positive half and the negative half.
1330       jlong neg_lo = lo;
1331       jlong neg_hi = (julong)-1 >> (juint)shift;
1332       jlong pos_lo = (julong) 0 >> (juint)shift;
1333       jlong pos_hi = hi;
1334       //lo = MIN2(neg_lo, pos_lo);  // == 0
1335       lo = neg_lo < pos_lo ? neg_lo : pos_lo;
1336       //hi = MAX2(neg_hi, pos_hi);  // == -1 >>> shift;
1337       hi = neg_hi > pos_hi ? neg_hi : pos_hi;
1338     }
1339     assert(lo <= hi, "must have valid bounds");
1340     const TypeLong* tl = TypeLong::make(lo, hi, MAX2(r1->_widen,r2->_widen));
1341     #ifdef ASSERT
1342     // Make sure we get the sign-capture idiom correct.
1343     if (shift == BitsPerJavaLong - 1) {
1344       if (r1->_lo >= 0) assert(tl == TypeLong::ZERO, ">>>63 of + is 0");
1345       if (r1->_hi < 0)  assert(tl == TypeLong::ONE,  ">>>63 of - is +1");
1346     }
1347     #endif
1348     return tl;
1349   }
1350 
1351   return TypeLong::LONG;                // Give up
1352 }