1 /*
   2  * Copyright (c) 1997, 2022, 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 "compiler/compileLog.hpp"
  27 #include "gc/shared/barrierSet.hpp"
  28 #include "gc/shared/c2/barrierSetC2.hpp"
  29 #include "memory/allocation.inline.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/cfgnode.hpp"
  33 #include "opto/inlinetypenode.hpp"
  34 #include "opto/loopnode.hpp"
  35 #include "opto/matcher.hpp"
  36 #include "opto/movenode.hpp"
  37 #include "opto/mulnode.hpp"
  38 #include "opto/opcodes.hpp"
  39 #include "opto/phaseX.hpp"
  40 #include "opto/subnode.hpp"
  41 #include "runtime/sharedRuntime.hpp"
  42 #include "utilities/moveBits.hpp"
  43 
  44 // Portions of code courtesy of Clifford Click
  45 
  46 // Optimization - Graph Style
  47 
  48 #include "math.h"
  49 
  50 //=============================================================================
  51 //------------------------------Identity---------------------------------------
  52 // If right input is a constant 0, return the left input.
  53 Node* SubNode::Identity(PhaseGVN* phase) {
  54   assert(in(1) != this, "Must already have called Value");
  55   assert(in(2) != this, "Must already have called Value");
  56 
  57   // Remove double negation
  58   const Type *zero = add_id();
  59   if( phase->type( in(1) )->higher_equal( zero ) &&
  60       in(2)->Opcode() == Opcode() &&
  61       phase->type( in(2)->in(1) )->higher_equal( zero ) ) {
  62     return in(2)->in(2);
  63   }
  64 
  65   // Convert "(X+Y) - Y" into X and "(X+Y) - X" into Y
  66   if (in(1)->Opcode() == Op_AddI || in(1)->Opcode() == Op_AddL) {
  67     if (in(1)->in(2) == in(2)) {
  68       return in(1)->in(1);
  69     }
  70     if (in(1)->in(1) == in(2)) {
  71       return in(1)->in(2);
  72     }
  73 
  74     // Also catch: "(X + Opaque2(Y)) - Y".  In this case, 'Y' is a loop-varying
  75     // trip counter and X is likely to be loop-invariant (that's how O2 Nodes
  76     // are originally used, although the optimizer sometimes jiggers things).
  77     // This folding through an O2 removes a loop-exit use of a loop-varying
  78     // value and generally lowers register pressure in and around the loop.
  79     if (in(1)->in(2)->Opcode() == Op_Opaque2 && in(1)->in(2)->in(1) == in(2)) {
  80       return in(1)->in(1);
  81     }
  82   }
  83 
  84   return ( phase->type( in(2) )->higher_equal( zero ) ) ? in(1) : this;
  85 }
  86 
  87 //------------------------------Value------------------------------------------
  88 // A subtract node differences it's two inputs.
  89 const Type* SubNode::Value_common(PhaseTransform *phase) const {
  90   const Node* in1 = in(1);
  91   const Node* in2 = in(2);
  92   // Either input is TOP ==> the result is TOP
  93   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
  94   if( t1 == Type::TOP ) return Type::TOP;
  95   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
  96   if( t2 == Type::TOP ) return Type::TOP;
  97 
  98   // Not correct for SubFnode and AddFNode (must check for infinity)
  99   // Equal?  Subtract is zero
 100   if (in1->eqv_uncast(in2))  return add_id();
 101 
 102   // Either input is BOTTOM ==> the result is the local BOTTOM
 103   if( t1 == Type::BOTTOM || t2 == Type::BOTTOM )
 104     return bottom_type();
 105 
 106   return NULL;
 107 }
 108 
 109 const Type* SubNode::Value(PhaseGVN* phase) const {
 110   const Type* t = Value_common(phase);
 111   if (t != NULL) {
 112     return t;
 113   }
 114   const Type* t1 = phase->type(in(1));
 115   const Type* t2 = phase->type(in(2));
 116   return sub(t1,t2);            // Local flavor of type subtraction
 117 
 118 }
 119 
 120 SubNode* SubNode::make(Node* in1, Node* in2, BasicType bt) {
 121   switch (bt) {
 122     case T_INT:
 123       return new SubINode(in1, in2);
 124     case T_LONG:
 125       return new SubLNode(in1, in2);
 126     default:
 127       fatal("Not implemented for %s", type2name(bt));
 128   }
 129   return NULL;
 130 }
 131 
 132 //=============================================================================
 133 //------------------------------Helper function--------------------------------
 134 
 135 static bool is_cloop_increment(Node* inc) {
 136   precond(inc->Opcode() == Op_AddI || inc->Opcode() == Op_AddL);
 137 
 138   if (!inc->in(1)->is_Phi()) {
 139     return false;
 140   }
 141   const PhiNode* phi = inc->in(1)->as_Phi();
 142 
 143   if (!phi->region()->is_CountedLoop()) {
 144     return false;
 145   }
 146 
 147   return inc == phi->region()->as_CountedLoop()->incr();
 148 }
 149 
 150 // Given the expression '(x + C) - v', or
 151 //                      'v - (x + C)', we examine nodes '+' and 'v':
 152 //
 153 //  1. Do not convert if '+' is a counted-loop increment, because the '-' is
 154 //     loop invariant and converting extends the live-range of 'x' to overlap
 155 //     with the '+', forcing another register to be used in the loop.
 156 //
 157 //  2. Do not convert if 'v' is a counted-loop induction variable, because
 158 //     'x' might be invariant.
 159 //
 160 static bool ok_to_convert(Node* inc, Node* var) {
 161   return !(is_cloop_increment(inc) || var->is_cloop_ind_var());
 162 }
 163 
 164 //------------------------------Ideal------------------------------------------
 165 Node *SubINode::Ideal(PhaseGVN *phase, bool can_reshape){
 166   Node *in1 = in(1);
 167   Node *in2 = in(2);
 168   uint op1 = in1->Opcode();
 169   uint op2 = in2->Opcode();
 170 
 171 #ifdef ASSERT
 172   // Check for dead loop
 173   if ((in1 == this) || (in2 == this) ||
 174       ((op1 == Op_AddI || op1 == Op_SubI) &&
 175        ((in1->in(1) == this) || (in1->in(2) == this) ||
 176         (in1->in(1) == in1)  || (in1->in(2) == in1)))) {
 177     assert(false, "dead loop in SubINode::Ideal");
 178   }
 179 #endif
 180 
 181   const Type *t2 = phase->type( in2 );
 182   if( t2 == Type::TOP ) return NULL;
 183   // Convert "x-c0" into "x+ -c0".
 184   if( t2->base() == Type::Int ){        // Might be bottom or top...
 185     const TypeInt *i = t2->is_int();
 186     if( i->is_con() )
 187       return new AddINode(in1, phase->intcon(-i->get_con()));
 188   }
 189 
 190   // Convert "(x+c0) - y" into (x-y) + c0"
 191   // Do not collapse (x+c0)-y if "+" is a loop increment or
 192   // if "y" is a loop induction variable.
 193   if( op1 == Op_AddI && ok_to_convert(in1, in2) ) {
 194     const Type *tadd = phase->type( in1->in(2) );
 195     if( tadd->singleton() && tadd != Type::TOP ) {
 196       Node *sub2 = phase->transform( new SubINode( in1->in(1), in2 ));
 197       return new AddINode( sub2, in1->in(2) );
 198     }
 199   }
 200 
 201   // Convert "x - (y+c0)" into "(x-y) - c0" AND
 202   // Convert "c1 - (y+c0)" into "(c1-c0) - y"
 203   // Need the same check as in above optimization but reversed.
 204   if (op2 == Op_AddI
 205       && ok_to_convert(in2, in1)
 206       && in2->in(2)->Opcode() == Op_ConI) {
 207     jint c0 = phase->type(in2->in(2))->isa_int()->get_con();
 208     Node* in21 = in2->in(1);
 209     if (in1->Opcode() == Op_ConI) {
 210       // Match c1
 211       jint c1 = phase->type(in1)->isa_int()->get_con();
 212       Node* sub2 = phase->intcon(java_subtract(c1, c0));
 213       return new SubINode(sub2, in21);
 214     } else {
 215       // Match x
 216       Node* sub2 = phase->transform(new SubINode(in1, in21));
 217       Node* neg_c0 = phase->intcon(-c0);
 218       return new AddINode(sub2, neg_c0);
 219     }
 220   }
 221 
 222   const Type *t1 = phase->type( in1 );
 223   if( t1 == Type::TOP ) return NULL;
 224 
 225 #ifdef ASSERT
 226   // Check for dead loop
 227   if ((op2 == Op_AddI || op2 == Op_SubI) &&
 228       ((in2->in(1) == this) || (in2->in(2) == this) ||
 229        (in2->in(1) == in2)  || (in2->in(2) == in2))) {
 230     assert(false, "dead loop in SubINode::Ideal");
 231   }
 232 #endif
 233 
 234   // Convert "x - (x+y)" into "-y"
 235   if (op2 == Op_AddI && in1 == in2->in(1)) {
 236     return new SubINode(phase->intcon(0), in2->in(2));
 237   }
 238   // Convert "(x-y) - x" into "-y"
 239   if (op1 == Op_SubI && in1->in(1) == in2) {
 240     return new SubINode(phase->intcon(0), in1->in(2));
 241   }
 242   // Convert "x - (y+x)" into "-y"
 243   if (op2 == Op_AddI && in1 == in2->in(2)) {
 244     return new SubINode(phase->intcon(0), in2->in(1));
 245   }
 246 
 247   // Convert "0 - (x-y)" into "y-x", leave the double negation "-(-y)" to SubNode::Identity().
 248   if (t1 == TypeInt::ZERO && op2 == Op_SubI && phase->type(in2->in(1)) != TypeInt::ZERO) {
 249     return new SubINode(in2->in(2), in2->in(1));
 250   }
 251 
 252   // Convert "0 - (x+con)" into "-con-x"
 253   jint con;
 254   if( t1 == TypeInt::ZERO && op2 == Op_AddI &&
 255       (con = in2->in(2)->find_int_con(0)) != 0 )
 256     return new SubINode( phase->intcon(-con), in2->in(1) );
 257 
 258   // Convert "(X+A) - (X+B)" into "A - B"
 259   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(1) == in2->in(1) )
 260     return new SubINode( in1->in(2), in2->in(2) );
 261 
 262   // Convert "(A+X) - (B+X)" into "A - B"
 263   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(2) == in2->in(2) )
 264     return new SubINode( in1->in(1), in2->in(1) );
 265 
 266   // Convert "(A+X) - (X+B)" into "A - B"
 267   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(2) == in2->in(1) )
 268     return new SubINode( in1->in(1), in2->in(2) );
 269 
 270   // Convert "(X+A) - (B+X)" into "A - B"
 271   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(1) == in2->in(2) )
 272     return new SubINode( in1->in(2), in2->in(1) );
 273 
 274   // Convert "A-(B-C)" into (A+C)-B", since add is commutative and generally
 275   // nicer to optimize than subtract.
 276   if( op2 == Op_SubI && in2->outcnt() == 1) {
 277     Node *add1 = phase->transform( new AddINode( in1, in2->in(2) ) );
 278     return new SubINode( add1, in2->in(1) );
 279   }
 280 
 281   // Associative
 282   if (op1 == Op_MulI && op2 == Op_MulI) {
 283     Node* sub_in1 = NULL;
 284     Node* sub_in2 = NULL;
 285     Node* mul_in = NULL;
 286 
 287     if (in1->in(1) == in2->in(1)) {
 288       // Convert "a*b-a*c into a*(b-c)
 289       sub_in1 = in1->in(2);
 290       sub_in2 = in2->in(2);
 291       mul_in = in1->in(1);
 292     } else if (in1->in(2) == in2->in(1)) {
 293       // Convert a*b-b*c into b*(a-c)
 294       sub_in1 = in1->in(1);
 295       sub_in2 = in2->in(2);
 296       mul_in = in1->in(2);
 297     } else if (in1->in(2) == in2->in(2)) {
 298       // Convert a*c-b*c into (a-b)*c
 299       sub_in1 = in1->in(1);
 300       sub_in2 = in2->in(1);
 301       mul_in = in1->in(2);
 302     } else if (in1->in(1) == in2->in(2)) {
 303       // Convert a*b-c*a into a*(b-c)
 304       sub_in1 = in1->in(2);
 305       sub_in2 = in2->in(1);
 306       mul_in = in1->in(1);
 307     }
 308 
 309     if (mul_in != NULL) {
 310       Node* sub = phase->transform(new SubINode(sub_in1, sub_in2));
 311       return new MulINode(mul_in, sub);
 312     }
 313   }
 314 
 315   // Convert "0-(A>>31)" into "(A>>>31)"
 316   if ( op2 == Op_RShiftI ) {
 317     Node *in21 = in2->in(1);
 318     Node *in22 = in2->in(2);
 319     const TypeInt *zero = phase->type(in1)->isa_int();
 320     const TypeInt *t21 = phase->type(in21)->isa_int();
 321     const TypeInt *t22 = phase->type(in22)->isa_int();
 322     if ( t21 && t22 && zero == TypeInt::ZERO && t22->is_con(31) ) {
 323       return new URShiftINode(in21, in22);
 324     }
 325   }
 326 
 327   return NULL;
 328 }
 329 
 330 //------------------------------sub--------------------------------------------
 331 // A subtract node differences it's two inputs.
 332 const Type *SubINode::sub( const Type *t1, const Type *t2 ) const {
 333   const TypeInt *r0 = t1->is_int(); // Handy access
 334   const TypeInt *r1 = t2->is_int();
 335   int32_t lo = java_subtract(r0->_lo, r1->_hi);
 336   int32_t hi = java_subtract(r0->_hi, r1->_lo);
 337 
 338   // We next check for 32-bit overflow.
 339   // If that happens, we just assume all integers are possible.
 340   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR
 341        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND
 342       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR
 343        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs
 344     return TypeInt::make(lo,hi,MAX2(r0->_widen,r1->_widen));
 345   else                          // Overflow; assume all integers
 346     return TypeInt::INT;
 347 }
 348 
 349 //=============================================================================
 350 //------------------------------Ideal------------------------------------------
 351 Node *SubLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 352   Node *in1 = in(1);
 353   Node *in2 = in(2);
 354   uint op1 = in1->Opcode();
 355   uint op2 = in2->Opcode();
 356 
 357 #ifdef ASSERT
 358   // Check for dead loop
 359   if ((in1 == this) || (in2 == this) ||
 360       ((op1 == Op_AddL || op1 == Op_SubL) &&
 361        ((in1->in(1) == this) || (in1->in(2) == this) ||
 362         (in1->in(1) == in1)  || (in1->in(2) == in1)))) {
 363     assert(false, "dead loop in SubLNode::Ideal");
 364   }
 365 #endif
 366 
 367   if( phase->type( in2 ) == Type::TOP ) return NULL;
 368   const TypeLong *i = phase->type( in2 )->isa_long();
 369   // Convert "x-c0" into "x+ -c0".
 370   if( i &&                      // Might be bottom or top...
 371       i->is_con() )
 372     return new AddLNode(in1, phase->longcon(-i->get_con()));
 373 
 374   // Convert "(x+c0) - y" into (x-y) + c0"
 375   // Do not collapse (x+c0)-y if "+" is a loop increment or
 376   // if "y" is a loop induction variable.
 377   if( op1 == Op_AddL && ok_to_convert(in1, in2) ) {
 378     Node *in11 = in1->in(1);
 379     const Type *tadd = phase->type( in1->in(2) );
 380     if( tadd->singleton() && tadd != Type::TOP ) {
 381       Node *sub2 = phase->transform( new SubLNode( in11, in2 ));
 382       return new AddLNode( sub2, in1->in(2) );
 383     }
 384   }
 385 
 386   // Convert "x - (y+c0)" into "(x-y) - c0" AND
 387   // Convert "c1 - (y+c0)" into "(c1-c0) - y"
 388   // Need the same check as in above optimization but reversed.
 389   if (op2 == Op_AddL
 390       && ok_to_convert(in2, in1)
 391       && in2->in(2)->Opcode() == Op_ConL) {
 392     jlong c0 = phase->type(in2->in(2))->isa_long()->get_con();
 393     Node* in21 = in2->in(1);
 394     if (in1->Opcode() == Op_ConL) {
 395       // Match c1
 396       jlong c1 = phase->type(in1)->isa_long()->get_con();
 397       Node* sub2 = phase->longcon(java_subtract(c1, c0));
 398       return new SubLNode(sub2, in21);
 399     } else {
 400       Node* sub2 = phase->transform(new SubLNode(in1, in21));
 401       Node* neg_c0 = phase->longcon(-c0);
 402       return new AddLNode(sub2, neg_c0);
 403     }
 404   }
 405 
 406   const Type *t1 = phase->type( in1 );
 407   if( t1 == Type::TOP ) return NULL;
 408 
 409 #ifdef ASSERT
 410   // Check for dead loop
 411   if ((op2 == Op_AddL || op2 == Op_SubL) &&
 412       ((in2->in(1) == this) || (in2->in(2) == this) ||
 413        (in2->in(1) == in2)  || (in2->in(2) == in2))) {
 414     assert(false, "dead loop in SubLNode::Ideal");
 415   }
 416 #endif
 417 
 418   // Convert "x - (x+y)" into "-y"
 419   if (op2 == Op_AddL && in1 == in2->in(1)) {
 420     return new SubLNode(phase->makecon(TypeLong::ZERO), in2->in(2));
 421   }
 422   // Convert "(x-y) - x" into "-y"
 423   if (op1 == Op_SubL && in1->in(1) == in2) {
 424     return new SubLNode(phase->makecon(TypeLong::ZERO), in1->in(2));
 425   }
 426   // Convert "x - (y+x)" into "-y"
 427   if (op2 == Op_AddL && in1 == in2->in(2)) {
 428     return new SubLNode(phase->makecon(TypeLong::ZERO), in2->in(1));
 429   }
 430 
 431   // Convert "0 - (x-y)" into "y-x", leave the double negation "-(-y)" to SubNode::Identity.
 432   if (t1 == TypeLong::ZERO && op2 == Op_SubL && phase->type(in2->in(1)) != TypeLong::ZERO) {
 433     return new SubLNode(in2->in(2), in2->in(1));
 434   }
 435 
 436   // Convert "(X+A) - (X+B)" into "A - B"
 437   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(1) == in2->in(1) )
 438     return new SubLNode( in1->in(2), in2->in(2) );
 439 
 440   // Convert "(A+X) - (B+X)" into "A - B"
 441   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(2) == in2->in(2) )
 442     return new SubLNode( in1->in(1), in2->in(1) );
 443 
 444   // Convert "(A+X) - (X+B)" into "A - B"
 445   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(2) == in2->in(1) )
 446     return new SubLNode( in1->in(1), in2->in(2) );
 447 
 448   // Convert "(X+A) - (B+X)" into "A - B"
 449   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(1) == in2->in(2) )
 450     return new SubLNode( in1->in(2), in2->in(1) );
 451 
 452   // Convert "A-(B-C)" into (A+C)-B"
 453   if( op2 == Op_SubL && in2->outcnt() == 1) {
 454     Node *add1 = phase->transform( new AddLNode( in1, in2->in(2) ) );
 455     return new SubLNode( add1, in2->in(1) );
 456   }
 457 
 458   // Associative
 459   if (op1 == Op_MulL && op2 == Op_MulL) {
 460     Node* sub_in1 = NULL;
 461     Node* sub_in2 = NULL;
 462     Node* mul_in = NULL;
 463 
 464     if (in1->in(1) == in2->in(1)) {
 465       // Convert "a*b-a*c into a*(b+c)
 466       sub_in1 = in1->in(2);
 467       sub_in2 = in2->in(2);
 468       mul_in = in1->in(1);
 469     } else if (in1->in(2) == in2->in(1)) {
 470       // Convert a*b-b*c into b*(a-c)
 471       sub_in1 = in1->in(1);
 472       sub_in2 = in2->in(2);
 473       mul_in = in1->in(2);
 474     } else if (in1->in(2) == in2->in(2)) {
 475       // Convert a*c-b*c into (a-b)*c
 476       sub_in1 = in1->in(1);
 477       sub_in2 = in2->in(1);
 478       mul_in = in1->in(2);
 479     } else if (in1->in(1) == in2->in(2)) {
 480       // Convert a*b-c*a into a*(b-c)
 481       sub_in1 = in1->in(2);
 482       sub_in2 = in2->in(1);
 483       mul_in = in1->in(1);
 484     }
 485 
 486     if (mul_in != NULL) {
 487       Node* sub = phase->transform(new SubLNode(sub_in1, sub_in2));
 488       return new MulLNode(mul_in, sub);
 489     }
 490   }
 491 
 492   // Convert "0L-(A>>63)" into "(A>>>63)"
 493   if ( op2 == Op_RShiftL ) {
 494     Node *in21 = in2->in(1);
 495     Node *in22 = in2->in(2);
 496     const TypeLong *zero = phase->type(in1)->isa_long();
 497     const TypeLong *t21 = phase->type(in21)->isa_long();
 498     const TypeInt *t22 = phase->type(in22)->isa_int();
 499     if ( t21 && t22 && zero == TypeLong::ZERO && t22->is_con(63) ) {
 500       return new URShiftLNode(in21, in22);
 501     }
 502   }
 503 
 504   return NULL;
 505 }
 506 
 507 //------------------------------sub--------------------------------------------
 508 // A subtract node differences it's two inputs.
 509 const Type *SubLNode::sub( const Type *t1, const Type *t2 ) const {
 510   const TypeLong *r0 = t1->is_long(); // Handy access
 511   const TypeLong *r1 = t2->is_long();
 512   jlong lo = java_subtract(r0->_lo, r1->_hi);
 513   jlong hi = java_subtract(r0->_hi, r1->_lo);
 514 
 515   // We next check for 32-bit overflow.
 516   // If that happens, we just assume all integers are possible.
 517   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR
 518        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND
 519       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR
 520        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs
 521     return TypeLong::make(lo,hi,MAX2(r0->_widen,r1->_widen));
 522   else                          // Overflow; assume all integers
 523     return TypeLong::LONG;
 524 }
 525 
 526 //=============================================================================
 527 //------------------------------Value------------------------------------------
 528 // A subtract node differences its two inputs.
 529 const Type* SubFPNode::Value(PhaseGVN* phase) const {
 530   const Node* in1 = in(1);
 531   const Node* in2 = in(2);
 532   // Either input is TOP ==> the result is TOP
 533   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
 534   if( t1 == Type::TOP ) return Type::TOP;
 535   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
 536   if( t2 == Type::TOP ) return Type::TOP;
 537 
 538   // if both operands are infinity of same sign, the result is NaN; do
 539   // not replace with zero
 540   if (t1->is_finite() && t2->is_finite() && in1 == in2) {
 541     return add_id();
 542   }
 543 
 544   // Either input is BOTTOM ==> the result is the local BOTTOM
 545   const Type *bot = bottom_type();
 546   if( (t1 == bot) || (t2 == bot) ||
 547       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 548     return bot;
 549 
 550   return sub(t1,t2);            // Local flavor of type subtraction
 551 }
 552 
 553 
 554 //=============================================================================
 555 //------------------------------Ideal------------------------------------------
 556 Node *SubFNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 557   const Type *t2 = phase->type( in(2) );
 558   // Convert "x-c0" into "x+ -c0".
 559   if( t2->base() == Type::FloatCon ) {  // Might be bottom or top...
 560     // return new (phase->C, 3) AddFNode(in(1), phase->makecon( TypeF::make(-t2->getf()) ) );
 561   }
 562 
 563   // Cannot replace 0.0-X with -X because a 'fsub' bytecode computes
 564   // 0.0-0.0 as +0.0, while a 'fneg' bytecode computes -0.0.
 565   //if( phase->type(in(1)) == TypeF::ZERO )
 566   //return new (phase->C, 2) NegFNode(in(2));
 567 
 568   return NULL;
 569 }
 570 
 571 //------------------------------sub--------------------------------------------
 572 // A subtract node differences its two inputs.
 573 const Type *SubFNode::sub( const Type *t1, const Type *t2 ) const {
 574   // no folding if one of operands is infinity or NaN, do not do constant folding
 575   if( g_isfinite(t1->getf()) && g_isfinite(t2->getf()) ) {
 576     return TypeF::make( t1->getf() - t2->getf() );
 577   }
 578   else if( g_isnan(t1->getf()) ) {
 579     return t1;
 580   }
 581   else if( g_isnan(t2->getf()) ) {
 582     return t2;
 583   }
 584   else {
 585     return Type::FLOAT;
 586   }
 587 }
 588 
 589 //=============================================================================
 590 //------------------------------Ideal------------------------------------------
 591 Node *SubDNode::Ideal(PhaseGVN *phase, bool can_reshape){
 592   const Type *t2 = phase->type( in(2) );
 593   // Convert "x-c0" into "x+ -c0".
 594   if( t2->base() == Type::DoubleCon ) { // Might be bottom or top...
 595     // return new (phase->C, 3) AddDNode(in(1), phase->makecon( TypeD::make(-t2->getd()) ) );
 596   }
 597 
 598   // Cannot replace 0.0-X with -X because a 'dsub' bytecode computes
 599   // 0.0-0.0 as +0.0, while a 'dneg' bytecode computes -0.0.
 600   //if( phase->type(in(1)) == TypeD::ZERO )
 601   //return new (phase->C, 2) NegDNode(in(2));
 602 
 603   return NULL;
 604 }
 605 
 606 //------------------------------sub--------------------------------------------
 607 // A subtract node differences its two inputs.
 608 const Type *SubDNode::sub( const Type *t1, const Type *t2 ) const {
 609   // no folding if one of operands is infinity or NaN, do not do constant folding
 610   if( g_isfinite(t1->getd()) && g_isfinite(t2->getd()) ) {
 611     return TypeD::make( t1->getd() - t2->getd() );
 612   }
 613   else if( g_isnan(t1->getd()) ) {
 614     return t1;
 615   }
 616   else if( g_isnan(t2->getd()) ) {
 617     return t2;
 618   }
 619   else {
 620     return Type::DOUBLE;
 621   }
 622 }
 623 
 624 //=============================================================================
 625 //------------------------------Idealize---------------------------------------
 626 // Unlike SubNodes, compare must still flatten return value to the
 627 // range -1, 0, 1.
 628 // And optimizations like those for (X + Y) - X fail if overflow happens.
 629 Node* CmpNode::Identity(PhaseGVN* phase) {
 630   return this;
 631 }
 632 
 633 CmpNode *CmpNode::make(Node *in1, Node *in2, BasicType bt, bool unsigned_comp) {
 634   switch (bt) {
 635     case T_INT:
 636       if (unsigned_comp) {
 637         return new CmpUNode(in1, in2);
 638       }
 639       return new CmpINode(in1, in2);
 640     case T_LONG:
 641       if (unsigned_comp) {
 642         return new CmpULNode(in1, in2);
 643       }
 644       return new CmpLNode(in1, in2);
 645     default:
 646       fatal("Not implemented for %s", type2name(bt));
 647   }
 648   return NULL;
 649 }
 650 
 651 //=============================================================================
 652 //------------------------------cmp--------------------------------------------
 653 // Simplify a CmpI (compare 2 integers) node, based on local information.
 654 // If both inputs are constants, compare them.
 655 const Type *CmpINode::sub( const Type *t1, const Type *t2 ) const {
 656   const TypeInt *r0 = t1->is_int(); // Handy access
 657   const TypeInt *r1 = t2->is_int();
 658 
 659   if( r0->_hi < r1->_lo )       // Range is always low?
 660     return TypeInt::CC_LT;
 661   else if( r0->_lo > r1->_hi )  // Range is always high?
 662     return TypeInt::CC_GT;
 663 
 664   else if( r0->is_con() && r1->is_con() ) { // comparing constants?
 665     assert(r0->get_con() == r1->get_con(), "must be equal");
 666     return TypeInt::CC_EQ;      // Equal results.
 667   } else if( r0->_hi == r1->_lo ) // Range is never high?
 668     return TypeInt::CC_LE;
 669   else if( r0->_lo == r1->_hi ) // Range is never low?
 670     return TypeInt::CC_GE;
 671   return TypeInt::CC;           // else use worst case results
 672 }
 673 
 674 // Simplify a CmpU (compare 2 integers) node, based on local information.
 675 // If both inputs are constants, compare them.
 676 const Type *CmpUNode::sub( const Type *t1, const Type *t2 ) const {
 677   assert(!t1->isa_ptr(), "obsolete usage of CmpU");
 678 
 679   // comparing two unsigned ints
 680   const TypeInt *r0 = t1->is_int();   // Handy access
 681   const TypeInt *r1 = t2->is_int();
 682 
 683   // Current installed version
 684   // Compare ranges for non-overlap
 685   juint lo0 = r0->_lo;
 686   juint hi0 = r0->_hi;
 687   juint lo1 = r1->_lo;
 688   juint hi1 = r1->_hi;
 689 
 690   // If either one has both negative and positive values,
 691   // it therefore contains both 0 and -1, and since [0..-1] is the
 692   // full unsigned range, the type must act as an unsigned bottom.
 693   bool bot0 = ((jint)(lo0 ^ hi0) < 0);
 694   bool bot1 = ((jint)(lo1 ^ hi1) < 0);
 695 
 696   if (bot0 || bot1) {
 697     // All unsigned values are LE -1 and GE 0.
 698     if (lo0 == 0 && hi0 == 0) {
 699       return TypeInt::CC_LE;            //   0 <= bot
 700     } else if ((jint)lo0 == -1 && (jint)hi0 == -1) {
 701       return TypeInt::CC_GE;            // -1 >= bot
 702     } else if (lo1 == 0 && hi1 == 0) {
 703       return TypeInt::CC_GE;            // bot >= 0
 704     } else if ((jint)lo1 == -1 && (jint)hi1 == -1) {
 705       return TypeInt::CC_LE;            // bot <= -1
 706     }
 707   } else {
 708     // We can use ranges of the form [lo..hi] if signs are the same.
 709     assert(lo0 <= hi0 && lo1 <= hi1, "unsigned ranges are valid");
 710     // results are reversed, '-' > '+' for unsigned compare
 711     if (hi0 < lo1) {
 712       return TypeInt::CC_LT;            // smaller
 713     } else if (lo0 > hi1) {
 714       return TypeInt::CC_GT;            // greater
 715     } else if (hi0 == lo1 && lo0 == hi1) {
 716       return TypeInt::CC_EQ;            // Equal results
 717     } else if (lo0 >= hi1) {
 718       return TypeInt::CC_GE;
 719     } else if (hi0 <= lo1) {
 720       // Check for special case in Hashtable::get.  (See below.)
 721       if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 722         return TypeInt::CC_LT;
 723       return TypeInt::CC_LE;
 724     }
 725   }
 726   // Check for special case in Hashtable::get - the hash index is
 727   // mod'ed to the table size so the following range check is useless.
 728   // Check for: (X Mod Y) CmpU Y, where the mod result and Y both have
 729   // to be positive.
 730   // (This is a gross hack, since the sub method never
 731   // looks at the structure of the node in any other case.)
 732   if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 733     return TypeInt::CC_LT;
 734   return TypeInt::CC;                   // else use worst case results
 735 }
 736 
 737 const Type* CmpUNode::Value(PhaseGVN* phase) const {
 738   const Type* t = SubNode::Value_common(phase);
 739   if (t != NULL) {
 740     return t;
 741   }
 742   const Node* in1 = in(1);
 743   const Node* in2 = in(2);
 744   const Type* t1 = phase->type(in1);
 745   const Type* t2 = phase->type(in2);
 746   assert(t1->isa_int(), "CmpU has only Int type inputs");
 747   if (t2 == TypeInt::INT) { // Compare to bottom?
 748     return bottom_type();
 749   }
 750   uint in1_op = in1->Opcode();
 751   if (in1_op == Op_AddI || in1_op == Op_SubI) {
 752     // The problem rise when result of AddI(SubI) may overflow
 753     // signed integer value. Let say the input type is
 754     // [256, maxint] then +128 will create 2 ranges due to
 755     // overflow: [minint, minint+127] and [384, maxint].
 756     // But C2 type system keep only 1 type range and as result
 757     // it use general [minint, maxint] for this case which we
 758     // can't optimize.
 759     //
 760     // Make 2 separate type ranges based on types of AddI(SubI) inputs
 761     // and compare results of their compare. If results are the same
 762     // CmpU node can be optimized.
 763     const Node* in11 = in1->in(1);
 764     const Node* in12 = in1->in(2);
 765     const Type* t11 = (in11 == in1) ? Type::TOP : phase->type(in11);
 766     const Type* t12 = (in12 == in1) ? Type::TOP : phase->type(in12);
 767     // Skip cases when input types are top or bottom.
 768     if ((t11 != Type::TOP) && (t11 != TypeInt::INT) &&
 769         (t12 != Type::TOP) && (t12 != TypeInt::INT)) {
 770       const TypeInt *r0 = t11->is_int();
 771       const TypeInt *r1 = t12->is_int();
 772       jlong lo_r0 = r0->_lo;
 773       jlong hi_r0 = r0->_hi;
 774       jlong lo_r1 = r1->_lo;
 775       jlong hi_r1 = r1->_hi;
 776       if (in1_op == Op_SubI) {
 777         jlong tmp = hi_r1;
 778         hi_r1 = -lo_r1;
 779         lo_r1 = -tmp;
 780         // Note, for substructing [minint,x] type range
 781         // long arithmetic provides correct overflow answer.
 782         // The confusion come from the fact that in 32-bit
 783         // -minint == minint but in 64-bit -minint == maxint+1.
 784       }
 785       jlong lo_long = lo_r0 + lo_r1;
 786       jlong hi_long = hi_r0 + hi_r1;
 787       int lo_tr1 = min_jint;
 788       int hi_tr1 = (int)hi_long;
 789       int lo_tr2 = (int)lo_long;
 790       int hi_tr2 = max_jint;
 791       bool underflow = lo_long != (jlong)lo_tr2;
 792       bool overflow  = hi_long != (jlong)hi_tr1;
 793       // Use sub(t1, t2) when there is no overflow (one type range)
 794       // or when both overflow and underflow (too complex).
 795       if ((underflow != overflow) && (hi_tr1 < lo_tr2)) {
 796         // Overflow only on one boundary, compare 2 separate type ranges.
 797         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
 798         const TypeInt* tr1 = TypeInt::make(lo_tr1, hi_tr1, w);
 799         const TypeInt* tr2 = TypeInt::make(lo_tr2, hi_tr2, w);
 800         const TypeInt* cmp1 = sub(tr1, t2)->is_int();
 801         const TypeInt* cmp2 = sub(tr2, t2)->is_int();
 802         // compute union, so that cmp handles all possible results from the two cases
 803         return cmp1->meet(cmp2);
 804       }
 805     }
 806   }
 807 
 808   return sub(t1, t2);            // Local flavor of type subtraction
 809 }
 810 
 811 bool CmpUNode::is_index_range_check() const {
 812   // Check for the "(X ModI Y) CmpU Y" shape
 813   return (in(1)->Opcode() == Op_ModI &&
 814           in(1)->in(2)->eqv_uncast(in(2)));
 815 }
 816 
 817 //------------------------------Idealize---------------------------------------
 818 Node *CmpINode::Ideal( PhaseGVN *phase, bool can_reshape ) {
 819   if (phase->type(in(2))->higher_equal(TypeInt::ZERO)) {
 820     switch (in(1)->Opcode()) {
 821     case Op_CmpU3:              // Collapse a CmpU3/CmpI into a CmpU
 822       return new CmpUNode(in(1)->in(1),in(1)->in(2));
 823     case Op_CmpL3:              // Collapse a CmpL3/CmpI into a CmpL
 824       return new CmpLNode(in(1)->in(1),in(1)->in(2));
 825     case Op_CmpUL3:             // Collapse a CmpUL3/CmpI into a CmpUL
 826       return new CmpULNode(in(1)->in(1),in(1)->in(2));
 827     case Op_CmpF3:              // Collapse a CmpF3/CmpI into a CmpF
 828       return new CmpFNode(in(1)->in(1),in(1)->in(2));
 829     case Op_CmpD3:              // Collapse a CmpD3/CmpI into a CmpD
 830       return new CmpDNode(in(1)->in(1),in(1)->in(2));
 831     //case Op_SubI:
 832       // If (x - y) cannot overflow, then ((x - y) <?> 0)
 833       // can be turned into (x <?> y).
 834       // This is handled (with more general cases) by Ideal_sub_algebra.
 835     }
 836   }
 837   return NULL;                  // No change
 838 }
 839 
 840 //------------------------------Ideal------------------------------------------
 841 Node* CmpLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
 842   Node* a = NULL;
 843   Node* b = NULL;
 844   if (is_double_null_check(phase, a, b) && (phase->type(a)->is_zero_type() || phase->type(b)->is_zero_type())) {
 845     // Degraded to a simple null check, use old acmp
 846     return new CmpPNode(a, b);
 847   }
 848   const TypeLong *t2 = phase->type(in(2))->isa_long();
 849   if (Opcode() == Op_CmpL && in(1)->Opcode() == Op_ConvI2L && t2 && t2->is_con()) {
 850     const jlong con = t2->get_con();
 851     if (con >= min_jint && con <= max_jint) {
 852       return new CmpINode(in(1)->in(1), phase->intcon((jint)con));
 853     }
 854   }
 855   return NULL;
 856 }
 857 
 858 // Match double null check emitted by Compile::optimize_acmp()
 859 bool CmpLNode::is_double_null_check(PhaseGVN* phase, Node*& a, Node*& b) const {
 860   if (in(1)->Opcode() == Op_OrL &&
 861       in(1)->in(1)->Opcode() == Op_CastP2X &&
 862       in(1)->in(2)->Opcode() == Op_CastP2X &&
 863       in(2)->bottom_type()->is_zero_type()) {
 864     assert(EnableValhalla, "unexpected double null check");
 865     a = in(1)->in(1)->in(1);
 866     b = in(1)->in(2)->in(1);
 867     return true;
 868   }
 869   return false;
 870 }
 871 
 872 //------------------------------Value------------------------------------------
 873 const Type* CmpLNode::Value(PhaseGVN* phase) const {
 874   Node* a = NULL;
 875   Node* b = NULL;
 876   if (is_double_null_check(phase, a, b) && (!phase->type(a)->maybe_null() || !phase->type(b)->maybe_null())) {
 877     // One operand is never NULL, emit constant false
 878     return TypeInt::CC_GT;
 879   }
 880   return SubNode::Value(phase);
 881 }
 882 
 883 //=============================================================================
 884 // Simplify a CmpL (compare 2 longs ) node, based on local information.
 885 // If both inputs are constants, compare them.
 886 const Type *CmpLNode::sub( const Type *t1, const Type *t2 ) const {
 887   const TypeLong *r0 = t1->is_long(); // Handy access
 888   const TypeLong *r1 = t2->is_long();
 889 
 890   if( r0->_hi < r1->_lo )       // Range is always low?
 891     return TypeInt::CC_LT;
 892   else if( r0->_lo > r1->_hi )  // Range is always high?
 893     return TypeInt::CC_GT;
 894 
 895   else if( r0->is_con() && r1->is_con() ) { // comparing constants?
 896     assert(r0->get_con() == r1->get_con(), "must be equal");
 897     return TypeInt::CC_EQ;      // Equal results.
 898   } else if( r0->_hi == r1->_lo ) // Range is never high?
 899     return TypeInt::CC_LE;
 900   else if( r0->_lo == r1->_hi ) // Range is never low?
 901     return TypeInt::CC_GE;
 902   return TypeInt::CC;           // else use worst case results
 903 }
 904 
 905 
 906 // Simplify a CmpUL (compare 2 unsigned longs) node, based on local information.
 907 // If both inputs are constants, compare them.
 908 const Type* CmpULNode::sub(const Type* t1, const Type* t2) const {
 909   assert(!t1->isa_ptr(), "obsolete usage of CmpUL");
 910 
 911   // comparing two unsigned longs
 912   const TypeLong* r0 = t1->is_long();   // Handy access
 913   const TypeLong* r1 = t2->is_long();
 914 
 915   // Current installed version
 916   // Compare ranges for non-overlap
 917   julong lo0 = r0->_lo;
 918   julong hi0 = r0->_hi;
 919   julong lo1 = r1->_lo;
 920   julong hi1 = r1->_hi;
 921 
 922   // If either one has both negative and positive values,
 923   // it therefore contains both 0 and -1, and since [0..-1] is the
 924   // full unsigned range, the type must act as an unsigned bottom.
 925   bool bot0 = ((jlong)(lo0 ^ hi0) < 0);
 926   bool bot1 = ((jlong)(lo1 ^ hi1) < 0);
 927 
 928   if (bot0 || bot1) {
 929     // All unsigned values are LE -1 and GE 0.
 930     if (lo0 == 0 && hi0 == 0) {
 931       return TypeInt::CC_LE;            //   0 <= bot
 932     } else if ((jlong)lo0 == -1 && (jlong)hi0 == -1) {
 933       return TypeInt::CC_GE;            // -1 >= bot
 934     } else if (lo1 == 0 && hi1 == 0) {
 935       return TypeInt::CC_GE;            // bot >= 0
 936     } else if ((jlong)lo1 == -1 && (jlong)hi1 == -1) {
 937       return TypeInt::CC_LE;            // bot <= -1
 938     }
 939   } else {
 940     // We can use ranges of the form [lo..hi] if signs are the same.
 941     assert(lo0 <= hi0 && lo1 <= hi1, "unsigned ranges are valid");
 942     // results are reversed, '-' > '+' for unsigned compare
 943     if (hi0 < lo1) {
 944       return TypeInt::CC_LT;            // smaller
 945     } else if (lo0 > hi1) {
 946       return TypeInt::CC_GT;            // greater
 947     } else if (hi0 == lo1 && lo0 == hi1) {
 948       return TypeInt::CC_EQ;            // Equal results
 949     } else if (lo0 >= hi1) {
 950       return TypeInt::CC_GE;
 951     } else if (hi0 <= lo1) {
 952       return TypeInt::CC_LE;
 953     }
 954   }
 955 
 956   return TypeInt::CC;                   // else use worst case results
 957 }
 958 
 959 //=============================================================================
 960 //------------------------------sub--------------------------------------------
 961 // Simplify an CmpP (compare 2 pointers) node, based on local information.
 962 // If both inputs are constants, compare them.
 963 const Type *CmpPNode::sub( const Type *t1, const Type *t2 ) const {
 964   const TypePtr *r0 = t1->is_ptr(); // Handy access
 965   const TypePtr *r1 = t2->is_ptr();
 966 
 967   // Undefined inputs makes for an undefined result
 968   if( TypePtr::above_centerline(r0->_ptr) ||
 969       TypePtr::above_centerline(r1->_ptr) )
 970     return Type::TOP;
 971 
 972   if (r0 == r1 && r0->singleton()) {
 973     // Equal pointer constants (klasses, nulls, etc.)
 974     return TypeInt::CC_EQ;
 975   }
 976 
 977   // See if it is 2 unrelated classes.
 978   const TypeOopPtr* p0 = r0->isa_oopptr();
 979   const TypeOopPtr* p1 = r1->isa_oopptr();
 980   const TypeKlassPtr* k0 = r0->isa_klassptr();
 981   const TypeKlassPtr* k1 = r1->isa_klassptr();
 982   if ((p0 && p1) || (k0 && k1)) {
 983     if (p0 && p1) {
 984       Node* in1 = in(1)->uncast();
 985       Node* in2 = in(2)->uncast();
 986       AllocateNode* alloc1 = AllocateNode::Ideal_allocation(in1, NULL);
 987       AllocateNode* alloc2 = AllocateNode::Ideal_allocation(in2, NULL);
 988       if (MemNode::detect_ptr_independence(in1, alloc1, in2, alloc2, NULL)) {
 989         return TypeInt::CC_GT;  // different pointers
 990       }
 991     }
 992     bool    xklass0 = p0 ? p0->klass_is_exact() : k0->klass_is_exact();
 993     bool    xklass1 = p1 ? p1->klass_is_exact() : k1->klass_is_exact();
 994     bool unrelated_classes = false;
 995 
 996     if ((p0 && p0->is_same_java_type_as(p1)) ||
 997         (k0 && k0->is_same_java_type_as(k1))) {
 998     } else if ((p0 && !p1->maybe_java_subtype_of(p0) && !p0->maybe_java_subtype_of(p1)) ||
 999                (k0 && !k1->maybe_java_subtype_of(k0) && !k0->maybe_java_subtype_of(k1))) {
1000       unrelated_classes = true;
1001     } else if ((p0 && !p1->maybe_java_subtype_of(p0)) ||
1002                (k0 && !k1->maybe_java_subtype_of(k0))) {
1003       unrelated_classes = xklass1;
1004     } else if ((p0 && !p0->maybe_java_subtype_of(p1)) ||
1005                (k0 && !k0->maybe_java_subtype_of(k1))) {
1006       unrelated_classes = xklass0;
1007     }
1008     if (!unrelated_classes) {
1009       // Handle inline type arrays
1010       if ((r0->flatten_array() && r1->not_flatten_array()) ||
1011           (r1->flatten_array() && r0->not_flatten_array())) {
1012         // One type is flattened in arrays but the other type is not. Must be unrelated.
1013         unrelated_classes = true;
1014       } else if ((r0->is_not_flat() && r1->is_flat()) ||
1015                  (r1->is_not_flat() && r0->is_flat())) {
1016         // One type is a non-flattened array and the other type is a flattened array. Must be unrelated.
1017         unrelated_classes = true;
1018       } else if ((r0->is_not_null_free() && r1->is_null_free()) ||
1019                  (r1->is_not_null_free() && r0->is_null_free())) {
1020         // One type is a nullable array and the other type is a null-free array. Must be unrelated.
1021         unrelated_classes = true;
1022       }
1023     }
1024     if (unrelated_classes) {
1025       // The oops classes are known to be unrelated. If the joined PTRs of
1026       // two oops is not Null and not Bottom, then we are sure that one
1027       // of the two oops is non-null, and the comparison will always fail.
1028       TypePtr::PTR jp = r0->join_ptr(r1->_ptr);
1029       if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
1030         return TypeInt::CC_GT;
1031       }
1032     }
1033   }
1034 
1035   // Known constants can be compared exactly
1036   // Null can be distinguished from any NotNull pointers
1037   // Unknown inputs makes an unknown result
1038   if( r0->singleton() ) {
1039     intptr_t bits0 = r0->get_con();
1040     if( r1->singleton() )
1041       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;
1042     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;
1043   } else if( r1->singleton() ) {
1044     intptr_t bits1 = r1->get_con();
1045     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;
1046   } else
1047     return TypeInt::CC;
1048 }
1049 
1050 static inline Node* isa_java_mirror_load(PhaseGVN* phase, Node* n) {
1051   // Return the klass node for (indirect load from OopHandle)
1052   //   LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
1053   //   or NULL if not matching.
1054   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1055     n = bs->step_over_gc_barrier(n);
1056 
1057   if (n->Opcode() != Op_LoadP) return NULL;
1058 
1059   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
1060   if (!tp || tp->instance_klass() != phase->C->env()->Class_klass()) return NULL;
1061 
1062   Node* adr = n->in(MemNode::Address);
1063   // First load from OopHandle: ((OopHandle)mirror)->resolve(); may need barrier.
1064   if (adr->Opcode() != Op_LoadP || !phase->type(adr)->isa_rawptr()) return NULL;
1065   adr = adr->in(MemNode::Address);
1066 
1067   intptr_t off = 0;
1068   Node* k = AddPNode::Ideal_base_and_offset(adr, phase, off);
1069   if (k == NULL)  return NULL;
1070   const TypeKlassPtr* tkp = phase->type(k)->isa_klassptr();
1071   if (!tkp || off != in_bytes(Klass::java_mirror_offset())) return NULL;
1072 
1073   // We've found the klass node of a Java mirror load.
1074   return k;
1075 }
1076 
1077 static inline Node* isa_const_java_mirror(PhaseGVN* phase, Node* n) {
1078   // for ConP(Foo.class) return ConP(Foo.klass)
1079   // otherwise return NULL
1080   if (!n->is_Con()) return NULL;
1081 
1082   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
1083   if (!tp) return NULL;
1084 
1085   ciType* mirror_type = tp->java_mirror_type();
1086   // TypeInstPtr::java_mirror_type() returns non-NULL for compile-
1087   // time Class constants only.
1088   if (!mirror_type) return NULL;
1089 
1090   // x.getClass() == int.class can never be true (for all primitive types)
1091   // Return a ConP(NULL) node for this case.
1092   if (mirror_type->is_classless()) {
1093     return phase->makecon(TypePtr::NULL_PTR);
1094   }
1095 
1096   // return the ConP(Foo.klass)
1097   assert(mirror_type->is_klass(), "mirror_type should represent a Klass*");
1098   return phase->makecon(TypeKlassPtr::make(mirror_type->as_klass()));
1099 }
1100 
1101 //------------------------------Ideal------------------------------------------
1102 // Normalize comparisons between Java mirror loads to compare the klass instead.
1103 //
1104 // Also check for the case of comparing an unknown klass loaded from the primary
1105 // super-type array vs a known klass with no subtypes.  This amounts to
1106 // checking to see an unknown klass subtypes a known klass with no subtypes;
1107 // this only happens on an exact match.  We can shorten this test by 1 load.
1108 Node* CmpPNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1109   // TODO 8284443 in(1) could be cast?
1110   if (in(1)->is_InlineType() && phase->type(in(2))->is_zero_type()) {
1111     // Null checking a scalarized but nullable inline type. Check the IsInit
1112     // input instead of the oop input to avoid keeping buffer allocations alive.
1113     return new CmpINode(in(1)->as_InlineType()->get_is_init(), phase->intcon(0));
1114   }
1115 
1116   // Normalize comparisons between Java mirrors into comparisons of the low-
1117   // level klass, where a dependent load could be shortened.
1118   //
1119   // The new pattern has a nice effect of matching the same pattern used in the
1120   // fast path of instanceof/checkcast/Class.isInstance(), which allows
1121   // redundant exact type check be optimized away by GVN.
1122   // For example, in
1123   //   if (x.getClass() == Foo.class) {
1124   //     Foo foo = (Foo) x;
1125   //     // ... use a ...
1126   //   }
1127   // a CmpPNode could be shared between if_acmpne and checkcast
1128   {
1129     Node* k1 = isa_java_mirror_load(phase, in(1));
1130     Node* k2 = isa_java_mirror_load(phase, in(2));
1131     Node* conk2 = isa_const_java_mirror(phase, in(2));
1132 
1133     if (k1 && (k2 || conk2)) {
1134       Node* lhs = k1;
1135       Node* rhs = (k2 != NULL) ? k2 : conk2;
1136       set_req_X(1, lhs, phase);
1137       set_req_X(2, rhs, phase);
1138       return this;
1139     }
1140   }
1141 
1142   // Constant pointer on right?
1143   const TypeKlassPtr* t2 = phase->type(in(2))->isa_klassptr();
1144   if (t2 == NULL || !t2->klass_is_exact())
1145     return NULL;
1146   // Get the constant klass we are comparing to.
1147   ciKlass* superklass = t2->exact_klass();
1148 
1149   // Now check for LoadKlass on left.
1150   Node* ldk1 = in(1);
1151   if (ldk1->is_DecodeNKlass()) {
1152     ldk1 = ldk1->in(1);
1153     if (ldk1->Opcode() != Op_LoadNKlass )
1154       return NULL;
1155   } else if (ldk1->Opcode() != Op_LoadKlass )
1156     return NULL;
1157   // Take apart the address of the LoadKlass:
1158   Node* adr1 = ldk1->in(MemNode::Address);
1159   intptr_t con2 = 0;
1160   Node* ldk2 = AddPNode::Ideal_base_and_offset(adr1, phase, con2);
1161   if (ldk2 == NULL)
1162     return NULL;
1163   if (con2 == oopDesc::klass_offset_in_bytes()) {
1164     // We are inspecting an object's concrete class.
1165     // Short-circuit the check if the query is abstract.
1166     if (superklass->is_interface() ||
1167         superklass->is_abstract()) {
1168       // Make it come out always false:
1169       this->set_req(2, phase->makecon(TypePtr::NULL_PTR));
1170       return this;
1171     }
1172   }
1173 
1174   // Check for a LoadKlass from primary supertype array.
1175   // Any nested loadklass from loadklass+con must be from the p.s. array.
1176   if (ldk2->is_DecodeNKlass()) {
1177     // Keep ldk2 as DecodeN since it could be used in CmpP below.
1178     if (ldk2->in(1)->Opcode() != Op_LoadNKlass )
1179       return NULL;
1180   } else if (ldk2->Opcode() != Op_LoadKlass)
1181     return NULL;
1182 
1183   // Verify that we understand the situation
1184   if (con2 != (intptr_t) superklass->super_check_offset())
1185     return NULL;                // Might be element-klass loading from array klass
1186 
1187   // Do not fold the subtype check to an array klass pointer comparison for [V? arrays.
1188   // [QMyValue is a subtype of [LMyValue but the klass for [QMyValue is not equal to
1189   // the klass for [LMyValue. Do not bypass the klass load from the primary supertype array.
1190   if (superklass->is_obj_array_klass() && !superklass->as_array_klass()->is_elem_null_free() &&
1191       superklass->as_array_klass()->element_klass()->is_inlinetype()) {
1192     return NULL;
1193   }
1194 
1195   // If 'superklass' has no subklasses and is not an interface, then we are
1196   // assured that the only input which will pass the type check is
1197   // 'superklass' itself.
1198   //
1199   // We could be more liberal here, and allow the optimization on interfaces
1200   // which have a single implementor.  This would require us to increase the
1201   // expressiveness of the add_dependency() mechanism.
1202   // %%% Do this after we fix TypeOopPtr:  Deps are expressive enough now.
1203 
1204   // Object arrays must have their base element have no subtypes
1205   while (superklass->is_obj_array_klass()) {
1206     ciType* elem = superklass->as_obj_array_klass()->element_type();
1207     superklass = elem->as_klass();
1208   }
1209   if (superklass->is_instance_klass()) {
1210     ciInstanceKlass* ik = superklass->as_instance_klass();
1211     if (ik->has_subklass() || ik->is_interface())  return NULL;
1212     // Add a dependency if there is a chance that a subclass will be added later.
1213     if (!ik->is_final()) {
1214       phase->C->dependencies()->assert_leaf_type(ik);
1215     }
1216   }
1217 
1218   // Bypass the dependent load, and compare directly
1219   this->set_req(1,ldk2);
1220 
1221   return this;
1222 }
1223 
1224 //=============================================================================
1225 //------------------------------sub--------------------------------------------
1226 // Simplify an CmpN (compare 2 pointers) node, based on local information.
1227 // If both inputs are constants, compare them.
1228 const Type *CmpNNode::sub( const Type *t1, const Type *t2 ) const {
1229   ShouldNotReachHere();
1230   return bottom_type();
1231 }
1232 
1233 //------------------------------Ideal------------------------------------------
1234 Node *CmpNNode::Ideal( PhaseGVN *phase, bool can_reshape ) {
1235   return NULL;
1236 }
1237 
1238 //=============================================================================
1239 //------------------------------Value------------------------------------------
1240 // Simplify an CmpF (compare 2 floats ) node, based on local information.
1241 // If both inputs are constants, compare them.
1242 const Type* CmpFNode::Value(PhaseGVN* phase) const {
1243   const Node* in1 = in(1);
1244   const Node* in2 = in(2);
1245   // Either input is TOP ==> the result is TOP
1246   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
1247   if( t1 == Type::TOP ) return Type::TOP;
1248   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
1249   if( t2 == Type::TOP ) return Type::TOP;
1250 
1251   // Not constants?  Don't know squat - even if they are the same
1252   // value!  If they are NaN's they compare to LT instead of EQ.
1253   const TypeF *tf1 = t1->isa_float_constant();
1254   const TypeF *tf2 = t2->isa_float_constant();
1255   if( !tf1 || !tf2 ) return TypeInt::CC;
1256 
1257   // This implements the Java bytecode fcmpl, so unordered returns -1.
1258   if( tf1->is_nan() || tf2->is_nan() )
1259     return TypeInt::CC_LT;
1260 
1261   if( tf1->_f < tf2->_f ) return TypeInt::CC_LT;
1262   if( tf1->_f > tf2->_f ) return TypeInt::CC_GT;
1263   assert( tf1->_f == tf2->_f, "do not understand FP behavior" );
1264   return TypeInt::CC_EQ;
1265 }
1266 
1267 
1268 //=============================================================================
1269 //------------------------------Value------------------------------------------
1270 // Simplify an CmpD (compare 2 doubles ) node, based on local information.
1271 // If both inputs are constants, compare them.
1272 const Type* CmpDNode::Value(PhaseGVN* phase) const {
1273   const Node* in1 = in(1);
1274   const Node* in2 = in(2);
1275   // Either input is TOP ==> the result is TOP
1276   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
1277   if( t1 == Type::TOP ) return Type::TOP;
1278   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
1279   if( t2 == Type::TOP ) return Type::TOP;
1280 
1281   // Not constants?  Don't know squat - even if they are the same
1282   // value!  If they are NaN's they compare to LT instead of EQ.
1283   const TypeD *td1 = t1->isa_double_constant();
1284   const TypeD *td2 = t2->isa_double_constant();
1285   if( !td1 || !td2 ) return TypeInt::CC;
1286 
1287   // This implements the Java bytecode dcmpl, so unordered returns -1.
1288   if( td1->is_nan() || td2->is_nan() )
1289     return TypeInt::CC_LT;
1290 
1291   if( td1->_d < td2->_d ) return TypeInt::CC_LT;
1292   if( td1->_d > td2->_d ) return TypeInt::CC_GT;
1293   assert( td1->_d == td2->_d, "do not understand FP behavior" );
1294   return TypeInt::CC_EQ;
1295 }
1296 
1297 //------------------------------Ideal------------------------------------------
1298 Node *CmpDNode::Ideal(PhaseGVN *phase, bool can_reshape){
1299   // Check if we can change this to a CmpF and remove a ConvD2F operation.
1300   // Change  (CMPD (F2D (float)) (ConD value))
1301   // To      (CMPF      (float)  (ConF value))
1302   // Valid when 'value' does not lose precision as a float.
1303   // Benefits: eliminates conversion, does not require 24-bit mode
1304 
1305   // NaNs prevent commuting operands.  This transform works regardless of the
1306   // order of ConD and ConvF2D inputs by preserving the original order.
1307   int idx_f2d = 1;              // ConvF2D on left side?
1308   if( in(idx_f2d)->Opcode() != Op_ConvF2D )
1309     idx_f2d = 2;                // No, swap to check for reversed args
1310   int idx_con = 3-idx_f2d;      // Check for the constant on other input
1311 
1312   if( ConvertCmpD2CmpF &&
1313       in(idx_f2d)->Opcode() == Op_ConvF2D &&
1314       in(idx_con)->Opcode() == Op_ConD ) {
1315     const TypeD *t2 = in(idx_con)->bottom_type()->is_double_constant();
1316     double t2_value_as_double = t2->_d;
1317     float  t2_value_as_float  = (float)t2_value_as_double;
1318     if( t2_value_as_double == (double)t2_value_as_float ) {
1319       // Test value can be represented as a float
1320       // Eliminate the conversion to double and create new comparison
1321       Node *new_in1 = in(idx_f2d)->in(1);
1322       Node *new_in2 = phase->makecon( TypeF::make(t2_value_as_float) );
1323       if( idx_f2d != 1 ) {      // Must flip args to match original order
1324         Node *tmp = new_in1;
1325         new_in1 = new_in2;
1326         new_in2 = tmp;
1327       }
1328       CmpFNode *new_cmp = (Opcode() == Op_CmpD3)
1329         ? new CmpF3Node( new_in1, new_in2 )
1330         : new CmpFNode ( new_in1, new_in2 ) ;
1331       return new_cmp;           // Changed to CmpFNode
1332     }
1333     // Testing value required the precision of a double
1334   }
1335   return NULL;                  // No change
1336 }
1337 
1338 //=============================================================================
1339 //------------------------------Value------------------------------------------
1340 const Type* FlatArrayCheckNode::Value(PhaseGVN* phase) const {
1341   bool all_not_flat = true;
1342   for (uint i = ArrayOrKlass; i < req(); ++i) {
1343     const Type* t = phase->type(in(i));
1344     if (t == Type::TOP) {
1345       return Type::TOP;
1346     }
1347     if (t->is_ptr()->is_flat()) {
1348       // One of the input arrays is flat, check always passes
1349       return TypeInt::CC_EQ;
1350     } else if (!t->is_ptr()->is_not_flat()) {
1351       // One of the input arrays might be flat
1352       all_not_flat = false;
1353     }
1354   }
1355   if (all_not_flat) {
1356     // None of the input arrays can be flat, check always fails
1357     return TypeInt::CC_GT;
1358   }
1359   return TypeInt::CC;
1360 }
1361 
1362 //------------------------------Ideal------------------------------------------
1363 Node* FlatArrayCheckNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1364   bool changed = false;
1365   // Remove inputs that are known to be non-flat
1366   for (uint i = ArrayOrKlass; i < req(); ++i) {
1367     const Type* t = phase->type(in(i));
1368     if (t->isa_ptr() && t->is_ptr()->is_not_flat()) {
1369       del_req(i--);
1370       changed = true;
1371     }
1372   }
1373   return changed ? this : NULL;
1374 }
1375 
1376 //=============================================================================
1377 //------------------------------cc2logical-------------------------------------
1378 // Convert a condition code type to a logical type
1379 const Type *BoolTest::cc2logical( const Type *CC ) const {
1380   if( CC == Type::TOP ) return Type::TOP;
1381   if( CC->base() != Type::Int ) return TypeInt::BOOL; // Bottom or worse
1382   const TypeInt *ti = CC->is_int();
1383   if( ti->is_con() ) {          // Only 1 kind of condition codes set?
1384     // Match low order 2 bits
1385     int tmp = ((ti->get_con()&3) == (_test&3)) ? 1 : 0;
1386     if( _test & 4 ) tmp = 1-tmp;     // Optionally complement result
1387     return TypeInt::make(tmp);       // Boolean result
1388   }
1389 
1390   if( CC == TypeInt::CC_GE ) {
1391     if( _test == ge ) return TypeInt::ONE;
1392     if( _test == lt ) return TypeInt::ZERO;
1393   }
1394   if( CC == TypeInt::CC_LE ) {
1395     if( _test == le ) return TypeInt::ONE;
1396     if( _test == gt ) return TypeInt::ZERO;
1397   }
1398 
1399   return TypeInt::BOOL;
1400 }
1401 
1402 //------------------------------dump_spec-------------------------------------
1403 // Print special per-node info
1404 void BoolTest::dump_on(outputStream *st) const {
1405   const char *msg[] = {"eq","gt","of","lt","ne","le","nof","ge"};
1406   st->print("%s", msg[_test]);
1407 }
1408 
1409 // Returns the logical AND of two tests (or 'never' if both tests can never be true).
1410 // For example, a test for 'le' followed by a test for 'lt' is equivalent with 'lt'.
1411 BoolTest::mask BoolTest::merge(BoolTest other) const {
1412   const mask res[illegal+1][illegal+1] = {
1413     // eq,      gt,      of,      lt,      ne,      le,      nof,     ge,      never,   illegal
1414       {eq,      never,   illegal, never,   never,   eq,      illegal, eq,      never,   illegal},  // eq
1415       {never,   gt,      illegal, never,   gt,      never,   illegal, gt,      never,   illegal},  // gt
1416       {illegal, illegal, illegal, illegal, illegal, illegal, illegal, illegal, never,   illegal},  // of
1417       {never,   never,   illegal, lt,      lt,      lt,      illegal, never,   never,   illegal},  // lt
1418       {never,   gt,      illegal, lt,      ne,      lt,      illegal, gt,      never,   illegal},  // ne
1419       {eq,      never,   illegal, lt,      lt,      le,      illegal, eq,      never,   illegal},  // le
1420       {illegal, illegal, illegal, illegal, illegal, illegal, illegal, illegal, never,   illegal},  // nof
1421       {eq,      gt,      illegal, never,   gt,      eq,      illegal, ge,      never,   illegal},  // ge
1422       {never,   never,   never,   never,   never,   never,   never,   never,   never,   illegal},  // never
1423       {illegal, illegal, illegal, illegal, illegal, illegal, illegal, illegal, illegal, illegal}}; // illegal
1424   return res[_test][other._test];
1425 }
1426 
1427 //=============================================================================
1428 uint BoolNode::hash() const { return (Node::hash() << 3)|(_test._test+1); }
1429 uint BoolNode::size_of() const { return sizeof(BoolNode); }
1430 
1431 //------------------------------operator==-------------------------------------
1432 bool BoolNode::cmp( const Node &n ) const {
1433   const BoolNode *b = (const BoolNode *)&n; // Cast up
1434   return (_test._test == b->_test._test);
1435 }
1436 
1437 //-------------------------------make_predicate--------------------------------
1438 Node* BoolNode::make_predicate(Node* test_value, PhaseGVN* phase) {
1439   if (test_value->is_Con())   return test_value;
1440   if (test_value->is_Bool())  return test_value;
1441   if (test_value->is_CMove() &&
1442       test_value->in(CMoveNode::Condition)->is_Bool()) {
1443     BoolNode*   bol   = test_value->in(CMoveNode::Condition)->as_Bool();
1444     const Type* ftype = phase->type(test_value->in(CMoveNode::IfFalse));
1445     const Type* ttype = phase->type(test_value->in(CMoveNode::IfTrue));
1446     if (ftype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ttype)) {
1447       return bol;
1448     } else if (ttype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ftype)) {
1449       return phase->transform( bol->negate(phase) );
1450     }
1451     // Else fall through.  The CMove gets in the way of the test.
1452     // It should be the case that make_predicate(bol->as_int_value()) == bol.
1453   }
1454   Node* cmp = new CmpINode(test_value, phase->intcon(0));
1455   cmp = phase->transform(cmp);
1456   Node* bol = new BoolNode(cmp, BoolTest::ne);
1457   return phase->transform(bol);
1458 }
1459 
1460 //--------------------------------as_int_value---------------------------------
1461 Node* BoolNode::as_int_value(PhaseGVN* phase) {
1462   // Inverse to make_predicate.  The CMove probably boils down to a Conv2B.
1463   Node* cmov = CMoveNode::make(NULL, this,
1464                                phase->intcon(0), phase->intcon(1),
1465                                TypeInt::BOOL);
1466   return phase->transform(cmov);
1467 }
1468 
1469 //----------------------------------negate-------------------------------------
1470 BoolNode* BoolNode::negate(PhaseGVN* phase) {
1471   return new BoolNode(in(1), _test.negate());
1472 }
1473 
1474 // Change "bool eq/ne (cmp (add/sub A B) C)" into false/true if add/sub
1475 // overflows and we can prove that C is not in the two resulting ranges.
1476 // This optimization is similar to the one performed by CmpUNode::Value().
1477 Node* BoolNode::fold_cmpI(PhaseGVN* phase, SubNode* cmp, Node* cmp1, int cmp_op,
1478                           int cmp1_op, const TypeInt* cmp2_type) {
1479   // Only optimize eq/ne integer comparison of add/sub
1480   if((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1481      (cmp_op == Op_CmpI) && (cmp1_op == Op_AddI || cmp1_op == Op_SubI)) {
1482     // Skip cases were inputs of add/sub are not integers or of bottom type
1483     const TypeInt* r0 = phase->type(cmp1->in(1))->isa_int();
1484     const TypeInt* r1 = phase->type(cmp1->in(2))->isa_int();
1485     if ((r0 != NULL) && (r0 != TypeInt::INT) &&
1486         (r1 != NULL) && (r1 != TypeInt::INT) &&
1487         (cmp2_type != TypeInt::INT)) {
1488       // Compute exact (long) type range of add/sub result
1489       jlong lo_long = r0->_lo;
1490       jlong hi_long = r0->_hi;
1491       if (cmp1_op == Op_AddI) {
1492         lo_long += r1->_lo;
1493         hi_long += r1->_hi;
1494       } else {
1495         lo_long -= r1->_hi;
1496         hi_long -= r1->_lo;
1497       }
1498       // Check for over-/underflow by casting to integer
1499       int lo_int = (int)lo_long;
1500       int hi_int = (int)hi_long;
1501       bool underflow = lo_long != (jlong)lo_int;
1502       bool overflow  = hi_long != (jlong)hi_int;
1503       if ((underflow != overflow) && (hi_int < lo_int)) {
1504         // Overflow on one boundary, compute resulting type ranges:
1505         // tr1 [MIN_INT, hi_int] and tr2 [lo_int, MAX_INT]
1506         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
1507         const TypeInt* tr1 = TypeInt::make(min_jint, hi_int, w);
1508         const TypeInt* tr2 = TypeInt::make(lo_int, max_jint, w);
1509         // Compare second input of cmp to both type ranges
1510         const Type* sub_tr1 = cmp->sub(tr1, cmp2_type);
1511         const Type* sub_tr2 = cmp->sub(tr2, cmp2_type);
1512         if (sub_tr1 == TypeInt::CC_LT && sub_tr2 == TypeInt::CC_GT) {
1513           // The result of the add/sub will never equal cmp2. Replace BoolNode
1514           // by false (0) if it tests for equality and by true (1) otherwise.
1515           return ConINode::make((_test._test == BoolTest::eq) ? 0 : 1);
1516         }
1517       }
1518     }
1519   }
1520   return NULL;
1521 }
1522 
1523 static bool is_counted_loop_cmp(Node *cmp) {
1524   Node *n = cmp->in(1)->in(1);
1525   return n != NULL &&
1526          n->is_Phi() &&
1527          n->in(0) != NULL &&
1528          n->in(0)->is_CountedLoop() &&
1529          n->in(0)->as_CountedLoop()->phi() == n;
1530 }
1531 
1532 //------------------------------Ideal------------------------------------------
1533 Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1534   // Change "bool tst (cmp con x)" into "bool ~tst (cmp x con)".
1535   // This moves the constant to the right.  Helps value-numbering.
1536   Node *cmp = in(1);
1537   if( !cmp->is_Sub() ) return NULL;
1538   int cop = cmp->Opcode();
1539   if( cop == Op_FastLock || cop == Op_FastUnlock || cmp->is_SubTypeCheck()) return NULL;
1540   Node *cmp1 = cmp->in(1);
1541   Node *cmp2 = cmp->in(2);
1542   if( !cmp1 ) return NULL;
1543 
1544   if (_test._test == BoolTest::overflow || _test._test == BoolTest::no_overflow) {
1545     return NULL;
1546   }
1547 
1548   const int cmp1_op = cmp1->Opcode();
1549   const int cmp2_op = cmp2->Opcode();
1550 
1551   // Constant on left?
1552   Node *con = cmp1;
1553   // Move constants to the right of compare's to canonicalize.
1554   // Do not muck with Opaque1 nodes, as this indicates a loop
1555   // guard that cannot change shape.
1556   if( con->is_Con() && !cmp2->is_Con() && cmp2_op != Op_Opaque1 &&
1557       // Because of NaN's, CmpD and CmpF are not commutative
1558       cop != Op_CmpD && cop != Op_CmpF &&
1559       // Protect against swapping inputs to a compare when it is used by a
1560       // counted loop exit, which requires maintaining the loop-limit as in(2)
1561       !is_counted_loop_exit_test() ) {
1562     // Ok, commute the constant to the right of the cmp node.
1563     // Clone the Node, getting a new Node of the same class
1564     cmp = cmp->clone();
1565     // Swap inputs to the clone
1566     cmp->swap_edges(1, 2);
1567     cmp = phase->transform( cmp );
1568     return new BoolNode( cmp, _test.commute() );
1569   }
1570 
1571   // Change "bool eq/ne (cmp (and X 16) 16)" into "bool ne/eq (cmp (and X 16) 0)".
1572   if (cop == Op_CmpI &&
1573       (_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1574       cmp1_op == Op_AndI && cmp2_op == Op_ConI &&
1575       cmp1->in(2)->Opcode() == Op_ConI) {
1576     const TypeInt *t12 = phase->type(cmp2)->isa_int();
1577     const TypeInt *t112 = phase->type(cmp1->in(2))->isa_int();
1578     if (t12 && t12->is_con() && t112 && t112->is_con() &&
1579         t12->get_con() == t112->get_con() && is_power_of_2(t12->get_con())) {
1580       Node *ncmp = phase->transform(new CmpINode(cmp1, phase->intcon(0)));
1581       return new BoolNode(ncmp, _test.negate());
1582     }
1583   }
1584 
1585   // Same for long type: change "bool eq/ne (cmp (and X 16) 16)" into "bool ne/eq (cmp (and X 16) 0)".
1586   if (cop == Op_CmpL &&
1587       (_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1588       cmp1_op == Op_AndL && cmp2_op == Op_ConL &&
1589       cmp1->in(2)->Opcode() == Op_ConL) {
1590     const TypeLong *t12 = phase->type(cmp2)->isa_long();
1591     const TypeLong *t112 = phase->type(cmp1->in(2))->isa_long();
1592     if (t12 && t12->is_con() && t112 && t112->is_con() &&
1593         t12->get_con() == t112->get_con() && is_power_of_2(t12->get_con())) {
1594       Node *ncmp = phase->transform(new CmpLNode(cmp1, phase->longcon(0)));
1595       return new BoolNode(ncmp, _test.negate());
1596     }
1597   }
1598 
1599   // Change "cmp (add X min_jint) (add Y min_jint)" into "cmpu X Y"
1600   // and    "cmp (add X min_jint) c" into "cmpu X (c + min_jint)"
1601   if (cop == Op_CmpI &&
1602       cmp1_op == Op_AddI &&
1603       phase->type(cmp1->in(2)) == TypeInt::MIN) {
1604     if (cmp2_op == Op_ConI) {
1605       Node* ncmp2 = phase->intcon(java_add(cmp2->get_int(), min_jint));
1606       Node* ncmp = phase->transform(new CmpUNode(cmp1->in(1), ncmp2));
1607       return new BoolNode(ncmp, _test._test);
1608     } else if (cmp2_op == Op_AddI &&
1609                phase->type(cmp2->in(2)) == TypeInt::MIN) {
1610       Node* ncmp = phase->transform(new CmpUNode(cmp1->in(1), cmp2->in(1)));
1611       return new BoolNode(ncmp, _test._test);
1612     }
1613   }
1614 
1615   // Change "cmp (add X min_jlong) (add Y min_jlong)" into "cmpu X Y"
1616   // and    "cmp (add X min_jlong) c" into "cmpu X (c + min_jlong)"
1617   if (cop == Op_CmpL &&
1618       cmp1_op == Op_AddL &&
1619       phase->type(cmp1->in(2)) == TypeLong::MIN) {
1620     if (cmp2_op == Op_ConL) {
1621       Node* ncmp2 = phase->longcon(java_add(cmp2->get_long(), min_jlong));
1622       Node* ncmp = phase->transform(new CmpULNode(cmp1->in(1), ncmp2));
1623       return new BoolNode(ncmp, _test._test);
1624     } else if (cmp2_op == Op_AddL &&
1625                phase->type(cmp2->in(2)) == TypeLong::MIN) {
1626       Node* ncmp = phase->transform(new CmpULNode(cmp1->in(1), cmp2->in(1)));
1627       return new BoolNode(ncmp, _test._test);
1628     }
1629   }
1630 
1631   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".
1632   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the
1633   // test instead.
1634   const TypeInt* cmp2_type = phase->type(cmp2)->isa_int();
1635   if (cmp2_type == NULL)  return NULL;
1636   Node* j_xor = cmp1;
1637   if( cmp2_type == TypeInt::ZERO &&
1638       cmp1_op == Op_XorI &&
1639       j_xor->in(1) != j_xor &&          // An xor of itself is dead
1640       phase->type( j_xor->in(1) ) == TypeInt::BOOL &&
1641       phase->type( j_xor->in(2) ) == TypeInt::ONE &&
1642       (_test._test == BoolTest::eq ||
1643        _test._test == BoolTest::ne) ) {
1644     Node *ncmp = phase->transform(new CmpINode(j_xor->in(1),cmp2));
1645     return new BoolNode( ncmp, _test.negate() );
1646   }
1647 
1648   // Change ((x & m) u<= m) or ((m & x) u<= m) to always true
1649   // Same with ((x & m) u< m+1) and ((m & x) u< m+1)
1650   if (cop == Op_CmpU &&
1651       cmp1_op == Op_AndI) {
1652     Node* bound = NULL;
1653     if (_test._test == BoolTest::le) {
1654       bound = cmp2;
1655     } else if (_test._test == BoolTest::lt &&
1656                cmp2->Opcode() == Op_AddI &&
1657                cmp2->in(2)->find_int_con(0) == 1) {
1658       bound = cmp2->in(1);
1659     }
1660     if (cmp1->in(2) == bound || cmp1->in(1) == bound) {
1661       return ConINode::make(1);
1662     }
1663   }
1664 
1665   // Change ((x & (m - 1)) u< m) into (m > 0)
1666   // This is the off-by-one variant of the above
1667   if (cop == Op_CmpU &&
1668       _test._test == BoolTest::lt &&
1669       cmp1_op == Op_AndI) {
1670     Node* l = cmp1->in(1);
1671     Node* r = cmp1->in(2);
1672     for (int repeat = 0; repeat < 2; repeat++) {
1673       bool match = r->Opcode() == Op_AddI && r->in(2)->find_int_con(0) == -1 &&
1674                    r->in(1) == cmp2;
1675       if (match) {
1676         // arraylength known to be non-negative, so a (arraylength != 0) is sufficient,
1677         // but to be compatible with the array range check pattern, use (arraylength u> 0)
1678         Node* ncmp = cmp2->Opcode() == Op_LoadRange
1679                      ? phase->transform(new CmpUNode(cmp2, phase->intcon(0)))
1680                      : phase->transform(new CmpINode(cmp2, phase->intcon(0)));
1681         return new BoolNode(ncmp, BoolTest::gt);
1682       } else {
1683         // commute and try again
1684         l = cmp1->in(2);
1685         r = cmp1->in(1);
1686       }
1687     }
1688   }
1689 
1690   // Change x u< 1 or x u<= 0 to x == 0
1691   // and    x u> 0 or u>= 1   to x != 0
1692   if (cop == Op_CmpU &&
1693       cmp1_op != Op_LoadRange &&
1694       (((_test._test == BoolTest::lt || _test._test == BoolTest::ge) &&
1695         cmp2->find_int_con(-1) == 1) ||
1696        ((_test._test == BoolTest::le || _test._test == BoolTest::gt) &&
1697         cmp2->find_int_con(-1) == 0))) {
1698     Node* ncmp = phase->transform(new CmpINode(cmp1, phase->intcon(0)));
1699     return new BoolNode(ncmp, _test.is_less() ? BoolTest::eq : BoolTest::ne);
1700   }
1701 
1702   // Change (arraylength <= 0) or (arraylength == 0)
1703   //   into (arraylength u<= 0)
1704   // Also change (arraylength != 0) into (arraylength u> 0)
1705   // The latter version matches the code pattern generated for
1706   // array range checks, which will more likely be optimized later.
1707   if (cop == Op_CmpI &&
1708       cmp1_op == Op_LoadRange &&
1709       cmp2->find_int_con(-1) == 0) {
1710     if (_test._test == BoolTest::le || _test._test == BoolTest::eq) {
1711       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1712       return new BoolNode(ncmp, BoolTest::le);
1713     } else if (_test._test == BoolTest::ne) {
1714       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1715       return new BoolNode(ncmp, BoolTest::gt);
1716     }
1717   }
1718 
1719   // Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".
1720   // This is a standard idiom for branching on a boolean value.
1721   Node *c2b = cmp1;
1722   if( cmp2_type == TypeInt::ZERO &&
1723       cmp1_op == Op_Conv2B &&
1724       (_test._test == BoolTest::eq ||
1725        _test._test == BoolTest::ne) ) {
1726     Node *ncmp = phase->transform(phase->type(c2b->in(1))->isa_int()
1727        ? (Node*)new CmpINode(c2b->in(1),cmp2)
1728        : (Node*)new CmpPNode(c2b->in(1),phase->makecon(TypePtr::NULL_PTR))
1729     );
1730     return new BoolNode( ncmp, _test._test );
1731   }
1732 
1733   // Comparing a SubI against a zero is equal to comparing the SubI
1734   // arguments directly.  This only works for eq and ne comparisons
1735   // due to possible integer overflow.
1736   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1737         (cop == Op_CmpI) &&
1738         (cmp1_op == Op_SubI) &&
1739         ( cmp2_type == TypeInt::ZERO ) ) {
1740     Node *ncmp = phase->transform( new CmpINode(cmp1->in(1),cmp1->in(2)));
1741     return new BoolNode( ncmp, _test._test );
1742   }
1743 
1744   // Same as above but with and AddI of a constant
1745   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1746       cop == Op_CmpI &&
1747       cmp1_op == Op_AddI &&
1748       cmp1->in(2) != NULL &&
1749       phase->type(cmp1->in(2))->isa_int() &&
1750       phase->type(cmp1->in(2))->is_int()->is_con() &&
1751       cmp2_type == TypeInt::ZERO &&
1752       !is_counted_loop_cmp(cmp) // modifying the exit test of a counted loop messes the counted loop shape
1753       ) {
1754     const TypeInt* cmp1_in2 = phase->type(cmp1->in(2))->is_int();
1755     Node *ncmp = phase->transform( new CmpINode(cmp1->in(1),phase->intcon(-cmp1_in2->_hi)));
1756     return new BoolNode( ncmp, _test._test );
1757   }
1758 
1759   // Change "bool eq/ne (cmp (phi (X -X) 0))" into "bool eq/ne (cmp X 0)"
1760   // since zero check of conditional negation of an integer is equal to
1761   // zero check of the integer directly.
1762   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1763       (cop == Op_CmpI) &&
1764       (cmp2_type == TypeInt::ZERO) &&
1765       (cmp1_op == Op_Phi)) {
1766     // There should be a diamond phi with true path at index 1 or 2
1767     PhiNode *phi = cmp1->as_Phi();
1768     int idx_true = phi->is_diamond_phi();
1769     if (idx_true != 0) {
1770       // True input is in(idx_true) while false input is in(3 - idx_true)
1771       Node *tin = phi->in(idx_true);
1772       Node *fin = phi->in(3 - idx_true);
1773       if ((tin->Opcode() == Op_SubI) &&
1774           (phase->type(tin->in(1)) == TypeInt::ZERO) &&
1775           (tin->in(2) == fin)) {
1776         // Found conditional negation at true path, create a new CmpINode without that
1777         Node *ncmp = phase->transform(new CmpINode(fin, cmp2));
1778         return new BoolNode(ncmp, _test._test);
1779       }
1780       if ((fin->Opcode() == Op_SubI) &&
1781           (phase->type(fin->in(1)) == TypeInt::ZERO) &&
1782           (fin->in(2) == tin)) {
1783         // Found conditional negation at false path, create a new CmpINode without that
1784         Node *ncmp = phase->transform(new CmpINode(tin, cmp2));
1785         return new BoolNode(ncmp, _test._test);
1786       }
1787     }
1788   }
1789 
1790   // Change (-A vs 0) into (A vs 0) by commuting the test.  Disallow in the
1791   // most general case because negating 0x80000000 does nothing.  Needed for
1792   // the CmpF3/SubI/CmpI idiom.
1793   if( cop == Op_CmpI &&
1794       cmp1_op == Op_SubI &&
1795       cmp2_type == TypeInt::ZERO &&
1796       phase->type( cmp1->in(1) ) == TypeInt::ZERO &&
1797       phase->type( cmp1->in(2) )->higher_equal(TypeInt::SYMINT) ) {
1798     Node *ncmp = phase->transform( new CmpINode(cmp1->in(2),cmp2));
1799     return new BoolNode( ncmp, _test.commute() );
1800   }
1801 
1802   // Try to optimize signed integer comparison
1803   return fold_cmpI(phase, cmp->as_Sub(), cmp1, cop, cmp1_op, cmp2_type);
1804 
1805   //  The transformation below is not valid for either signed or unsigned
1806   //  comparisons due to wraparound concerns at MAX_VALUE and MIN_VALUE.
1807   //  This transformation can be resurrected when we are able to
1808   //  make inferences about the range of values being subtracted from
1809   //  (or added to) relative to the wraparound point.
1810   //
1811   //    // Remove +/-1's if possible.
1812   //    // "X <= Y-1" becomes "X <  Y"
1813   //    // "X+1 <= Y" becomes "X <  Y"
1814   //    // "X <  Y+1" becomes "X <= Y"
1815   //    // "X-1 <  Y" becomes "X <= Y"
1816   //    // Do not this to compares off of the counted-loop-end.  These guys are
1817   //    // checking the trip counter and they want to use the post-incremented
1818   //    // counter.  If they use the PRE-incremented counter, then the counter has
1819   //    // to be incremented in a private block on a loop backedge.
1820   //    if( du && du->cnt(this) && du->out(this)[0]->Opcode() == Op_CountedLoopEnd )
1821   //      return NULL;
1822   //  #ifndef PRODUCT
1823   //    // Do not do this in a wash GVN pass during verification.
1824   //    // Gets triggered by too many simple optimizations to be bothered with
1825   //    // re-trying it again and again.
1826   //    if( !phase->allow_progress() ) return NULL;
1827   //  #endif
1828   //    // Not valid for unsigned compare because of corner cases in involving zero.
1829   //    // For example, replacing "X-1 <u Y" with "X <=u Y" fails to throw an
1830   //    // exception in case X is 0 (because 0-1 turns into 4billion unsigned but
1831   //    // "0 <=u Y" is always true).
1832   //    if( cmp->Opcode() == Op_CmpU ) return NULL;
1833   //    int cmp2_op = cmp2->Opcode();
1834   //    if( _test._test == BoolTest::le ) {
1835   //      if( cmp1_op == Op_AddI &&
1836   //          phase->type( cmp1->in(2) ) == TypeInt::ONE )
1837   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::lt );
1838   //      else if( cmp2_op == Op_AddI &&
1839   //         phase->type( cmp2->in(2) ) == TypeInt::MINUS_1 )
1840   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::lt );
1841   //    } else if( _test._test == BoolTest::lt ) {
1842   //      if( cmp1_op == Op_AddI &&
1843   //          phase->type( cmp1->in(2) ) == TypeInt::MINUS_1 )
1844   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::le );
1845   //      else if( cmp2_op == Op_AddI &&
1846   //         phase->type( cmp2->in(2) ) == TypeInt::ONE )
1847   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::le );
1848   //    }
1849 }
1850 
1851 //------------------------------Value------------------------------------------
1852 // Simplify a Bool (convert condition codes to boolean (1 or 0)) node,
1853 // based on local information.   If the input is constant, do it.
1854 const Type* BoolNode::Value(PhaseGVN* phase) const {
1855   return _test.cc2logical( phase->type( in(1) ) );
1856 }
1857 
1858 #ifndef PRODUCT
1859 //------------------------------dump_spec--------------------------------------
1860 // Dump special per-node info
1861 void BoolNode::dump_spec(outputStream *st) const {
1862   st->print("[");
1863   _test.dump_on(st);
1864   st->print("]");
1865 }
1866 #endif
1867 
1868 //----------------------is_counted_loop_exit_test------------------------------
1869 // Returns true if node is used by a counted loop node.
1870 bool BoolNode::is_counted_loop_exit_test() {
1871   for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
1872     Node* use = fast_out(i);
1873     if (use->is_CountedLoopEnd()) {
1874       return true;
1875     }
1876   }
1877   return false;
1878 }
1879 
1880 //=============================================================================
1881 //------------------------------Value------------------------------------------
1882 const Type* AbsNode::Value(PhaseGVN* phase) const {
1883   const Type* t1 = phase->type(in(1));
1884   if (t1 == Type::TOP) return Type::TOP;
1885 
1886   switch (t1->base()) {
1887   case Type::Int: {
1888     const TypeInt* ti = t1->is_int();
1889     if (ti->is_con()) {
1890       return TypeInt::make(uabs(ti->get_con()));
1891     }
1892     break;
1893   }
1894   case Type::Long: {
1895     const TypeLong* tl = t1->is_long();
1896     if (tl->is_con()) {
1897       return TypeLong::make(uabs(tl->get_con()));
1898     }
1899     break;
1900   }
1901   case Type::FloatCon:
1902     return TypeF::make(abs(t1->getf()));
1903   case Type::DoubleCon:
1904     return TypeD::make(abs(t1->getd()));
1905   default:
1906     break;
1907   }
1908 
1909   return bottom_type();
1910 }
1911 
1912 //------------------------------Identity----------------------------------------
1913 Node* AbsNode::Identity(PhaseGVN* phase) {
1914   Node* in1 = in(1);
1915   // No need to do abs for non-negative values
1916   if (phase->type(in1)->higher_equal(TypeInt::POS) ||
1917       phase->type(in1)->higher_equal(TypeLong::POS)) {
1918     return in1;
1919   }
1920   // Convert "abs(abs(x))" into "abs(x)"
1921   if (in1->Opcode() == Opcode()) {
1922     return in1;
1923   }
1924   return this;
1925 }
1926 
1927 //------------------------------Ideal------------------------------------------
1928 Node* AbsNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1929   Node* in1 = in(1);
1930   // Convert "abs(0-x)" into "abs(x)"
1931   if (in1->is_Sub() && phase->type(in1->in(1))->is_zero_type()) {
1932     set_req_X(1, in1->in(2), phase);
1933     return this;
1934   }
1935   return NULL;
1936 }
1937 
1938 //=============================================================================
1939 //------------------------------Value------------------------------------------
1940 // Compute sqrt
1941 const Type* SqrtDNode::Value(PhaseGVN* phase) const {
1942   const Type *t1 = phase->type( in(1) );
1943   if( t1 == Type::TOP ) return Type::TOP;
1944   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1945   double d = t1->getd();
1946   if( d < 0.0 ) return Type::DOUBLE;
1947   return TypeD::make( sqrt( d ) );
1948 }
1949 
1950 const Type* SqrtFNode::Value(PhaseGVN* phase) const {
1951   const Type *t1 = phase->type( in(1) );
1952   if( t1 == Type::TOP ) return Type::TOP;
1953   if( t1->base() != Type::FloatCon ) return Type::FLOAT;
1954   float f = t1->getf();
1955   if( f < 0.0f ) return Type::FLOAT;
1956   return TypeF::make( (float)sqrt( (double)f ) );
1957 }
1958 
1959 const Type* ReverseINode::Value(PhaseGVN* phase) const {
1960   const Type *t1 = phase->type( in(1) );
1961   if (t1 == Type::TOP) {
1962     return Type::TOP;
1963   }
1964   const TypeInt* t1int = t1->isa_int();
1965   if (t1int && t1int->is_con()) {
1966     jint res = reverse_bits(t1int->get_con());
1967     return TypeInt::make(res);
1968   }
1969   return bottom_type();
1970 }
1971 
1972 const Type* ReverseLNode::Value(PhaseGVN* phase) const {
1973   const Type *t1 = phase->type( in(1) );
1974   if (t1 == Type::TOP) {
1975     return Type::TOP;
1976   }
1977   const TypeLong* t1long = t1->isa_long();
1978   if (t1long && t1long->is_con()) {
1979     jlong res = reverse_bits(t1long->get_con());
1980     return TypeLong::make(res);
1981   }
1982   return bottom_type();
1983 }
1984 
1985 Node* ReverseINode::Identity(PhaseGVN* phase) {
1986   if (in(1)->Opcode() == Op_ReverseI) {
1987     return in(1)->in(1);
1988   }
1989   return this;
1990 }
1991 
1992 Node* ReverseLNode::Identity(PhaseGVN* phase) {
1993   if (in(1)->Opcode() == Op_ReverseL) {
1994     return in(1)->in(1);
1995   }
1996   return this;
1997 }