1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "compiler/compileLog.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "opto/addnode.hpp"
  29 #include "opto/callnode.hpp"
  30 #include "opto/cfgnode.hpp"
  31 #include "opto/loopnode.hpp"
  32 #include "opto/matcher.hpp"
  33 #include "opto/movenode.hpp"
  34 #include "opto/mulnode.hpp"
  35 #include "opto/opcodes.hpp"
  36 #include "opto/phaseX.hpp"
  37 #include "opto/subnode.hpp"
  38 #include "runtime/sharedRuntime.hpp"
  39 
  40 // Portions of code courtesy of Clifford Click
  41 
  42 // Optimization - Graph Style
  43 
  44 #include "math.h"
  45 
  46 //=============================================================================
  47 //------------------------------Identity---------------------------------------
  48 // If right input is a constant 0, return the left input.
  49 Node *SubNode::Identity( PhaseTransform *phase ) {
  50   assert(in(1) != this, "Must already have called Value");
  51   assert(in(2) != this, "Must already have called Value");
  52 
  53   // Remove double negation
  54   const Type *zero = add_id();
  55   if( phase->type( in(1) )->higher_equal( zero ) &&
  56       in(2)->Opcode() == Opcode() &&
  57       phase->type( in(2)->in(1) )->higher_equal( zero ) ) {
  58     return in(2)->in(2);
  59   }
  60 
  61   // Convert "(X+Y) - Y" into X and "(X+Y) - X" into Y
  62   if( in(1)->Opcode() == Op_AddI ) {
  63     if( phase->eqv(in(1)->in(2),in(2)) )
  64       return in(1)->in(1);
  65     if (phase->eqv(in(1)->in(1),in(2)))
  66       return in(1)->in(2);
  67 
  68     // Also catch: "(X + Opaque2(Y)) - Y".  In this case, 'Y' is a loop-varying
  69     // trip counter and X is likely to be loop-invariant (that's how O2 Nodes
  70     // are originally used, although the optimizer sometimes jiggers things).
  71     // This folding through an O2 removes a loop-exit use of a loop-varying
  72     // value and generally lowers register pressure in and around the loop.
  73     if( in(1)->in(2)->Opcode() == Op_Opaque2 &&
  74         phase->eqv(in(1)->in(2)->in(1),in(2)) )
  75       return in(1)->in(1);
  76   }
  77 
  78   return ( phase->type( in(2) )->higher_equal( zero ) ) ? in(1) : this;
  79 }
  80 
  81 //------------------------------Value------------------------------------------
  82 // A subtract node differences it's two inputs.
  83 const Type* SubNode::Value_common(PhaseTransform *phase) const {
  84   const Node* in1 = in(1);
  85   const Node* in2 = in(2);
  86   // Either input is TOP ==> the result is TOP
  87   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
  88   if( t1 == Type::TOP ) return Type::TOP;
  89   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
  90   if( t2 == Type::TOP ) return Type::TOP;
  91 
  92   // Not correct for SubFnode and AddFNode (must check for infinity)
  93   // Equal?  Subtract is zero
  94   if (in1->eqv_uncast(in2))  return add_id();
  95 
  96   // Either input is BOTTOM ==> the result is the local BOTTOM
  97   if( t1 == Type::BOTTOM || t2 == Type::BOTTOM )
  98     return bottom_type();
  99 
 100   return NULL;
 101 }
 102 
 103 const Type* SubNode::Value(PhaseTransform *phase) const {
 104   const Type* t = Value_common(phase);
 105   if (t != NULL) {
 106     return t;
 107   }
 108   const Type* t1 = phase->type(in(1));
 109   const Type* t2 = phase->type(in(2));
 110   return sub(t1,t2);            // Local flavor of type subtraction
 111 
 112 }
 113 
 114 //=============================================================================
 115 
 116 //------------------------------Helper function--------------------------------
 117 static bool ok_to_convert(Node* inc, Node* iv) {
 118     // Do not collapse (x+c0)-y if "+" is a loop increment, because the
 119     // "-" is loop invariant and collapsing extends the live-range of "x"
 120     // to overlap with the "+", forcing another register to be used in
 121     // the loop.
 122     // This test will be clearer with '&&' (apply DeMorgan's rule)
 123     // but I like the early cutouts that happen here.
 124     const PhiNode *phi;
 125     if( ( !inc->in(1)->is_Phi() ||
 126           !(phi=inc->in(1)->as_Phi()) ||
 127           phi->is_copy() ||
 128           !phi->region()->is_CountedLoop() ||
 129           inc != phi->region()->as_CountedLoop()->incr() )
 130        &&
 131         // Do not collapse (x+c0)-iv if "iv" is a loop induction variable,
 132         // because "x" maybe invariant.
 133         ( !iv->is_loop_iv() )
 134       ) {
 135       return true;
 136     } else {
 137       return false;
 138     }
 139 }
 140 //------------------------------Ideal------------------------------------------
 141 Node *SubINode::Ideal(PhaseGVN *phase, bool can_reshape){
 142   Node *in1 = in(1);
 143   Node *in2 = in(2);
 144   uint op1 = in1->Opcode();
 145   uint op2 = in2->Opcode();
 146 
 147 #ifdef ASSERT
 148   // Check for dead loop
 149   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||
 150       ( op1 == Op_AddI || op1 == Op_SubI ) &&
 151       ( phase->eqv( in1->in(1), this ) || phase->eqv( in1->in(2), this ) ||
 152         phase->eqv( in1->in(1), in1  ) || phase->eqv( in1->in(2), in1 ) ) )
 153     assert(false, "dead loop in SubINode::Ideal");
 154 #endif
 155 
 156   const Type *t2 = phase->type( in2 );
 157   if( t2 == Type::TOP ) return NULL;
 158   // Convert "x-c0" into "x+ -c0".
 159   if( t2->base() == Type::Int ){        // Might be bottom or top...
 160     const TypeInt *i = t2->is_int();
 161     if( i->is_con() )
 162       return new AddINode(in1, phase->intcon(-i->get_con()));
 163   }
 164 
 165   // Convert "(x+c0) - y" into (x-y) + c0"
 166   // Do not collapse (x+c0)-y if "+" is a loop increment or
 167   // if "y" is a loop induction variable.
 168   if( op1 == Op_AddI && ok_to_convert(in1, in2) ) {
 169     const Type *tadd = phase->type( in1->in(2) );
 170     if( tadd->singleton() && tadd != Type::TOP ) {
 171       Node *sub2 = phase->transform( new SubINode( in1->in(1), in2 ));
 172       return new AddINode( sub2, in1->in(2) );
 173     }
 174   }
 175 
 176 
 177   // Convert "x - (y+c0)" into "(x-y) - c0"
 178   // Need the same check as in above optimization but reversed.
 179   if (op2 == Op_AddI && ok_to_convert(in2, in1)) {
 180     Node* in21 = in2->in(1);
 181     Node* in22 = in2->in(2);
 182     const TypeInt* tcon = phase->type(in22)->isa_int();
 183     if (tcon != NULL && tcon->is_con()) {
 184       Node* sub2 = phase->transform( new SubINode(in1, in21) );
 185       Node* neg_c0 = phase->intcon(- tcon->get_con());
 186       return new AddINode(sub2, neg_c0);
 187     }
 188   }
 189 
 190   const Type *t1 = phase->type( in1 );
 191   if( t1 == Type::TOP ) return NULL;
 192 
 193 #ifdef ASSERT
 194   // Check for dead loop
 195   if( ( op2 == Op_AddI || op2 == Op_SubI ) &&
 196       ( phase->eqv( in2->in(1), this ) || phase->eqv( in2->in(2), this ) ||
 197         phase->eqv( in2->in(1), in2  ) || phase->eqv( in2->in(2), in2  ) ) )
 198     assert(false, "dead loop in SubINode::Ideal");
 199 #endif
 200 
 201   // Convert "x - (x+y)" into "-y"
 202   if( op2 == Op_AddI &&
 203       phase->eqv( in1, in2->in(1) ) )
 204     return new SubINode( phase->intcon(0),in2->in(2));
 205   // Convert "(x-y) - x" into "-y"
 206   if( op1 == Op_SubI &&
 207       phase->eqv( in1->in(1), in2 ) )
 208     return new SubINode( phase->intcon(0),in1->in(2));
 209   // Convert "x - (y+x)" into "-y"
 210   if( op2 == Op_AddI &&
 211       phase->eqv( in1, in2->in(2) ) )
 212     return new SubINode( phase->intcon(0),in2->in(1));
 213 
 214   // Convert "0 - (x-y)" into "y-x"
 215   if( t1 == TypeInt::ZERO && op2 == Op_SubI )
 216     return new SubINode( in2->in(2), in2->in(1) );
 217 
 218   // Convert "0 - (x+con)" into "-con-x"
 219   jint con;
 220   if( t1 == TypeInt::ZERO && op2 == Op_AddI &&
 221       (con = in2->in(2)->find_int_con(0)) != 0 )
 222     return new SubINode( phase->intcon(-con), in2->in(1) );
 223 
 224   // Convert "(X+A) - (X+B)" into "A - B"
 225   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(1) == in2->in(1) )
 226     return new SubINode( in1->in(2), in2->in(2) );
 227 
 228   // Convert "(A+X) - (B+X)" into "A - B"
 229   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(2) == in2->in(2) )
 230     return new SubINode( in1->in(1), in2->in(1) );
 231 
 232   // Convert "(A+X) - (X+B)" into "A - B"
 233   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(2) == in2->in(1) )
 234     return new SubINode( in1->in(1), in2->in(2) );
 235 
 236   // Convert "(X+A) - (B+X)" into "A - B"
 237   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(1) == in2->in(2) )
 238     return new SubINode( in1->in(2), in2->in(1) );
 239 
 240   // Convert "A-(B-C)" into (A+C)-B", since add is commutative and generally
 241   // nicer to optimize than subtract.
 242   if( op2 == Op_SubI && in2->outcnt() == 1) {
 243     Node *add1 = phase->transform( new AddINode( in1, in2->in(2) ) );
 244     return new SubINode( add1, in2->in(1) );
 245   }
 246 
 247   return NULL;
 248 }
 249 
 250 //------------------------------sub--------------------------------------------
 251 // A subtract node differences it's two inputs.
 252 const Type *SubINode::sub( const Type *t1, const Type *t2 ) const {
 253   const TypeInt *r0 = t1->is_int(); // Handy access
 254   const TypeInt *r1 = t2->is_int();
 255   int32_t lo = r0->_lo - r1->_hi;
 256   int32_t hi = r0->_hi - r1->_lo;
 257 
 258   // We next check for 32-bit overflow.
 259   // If that happens, we just assume all integers are possible.
 260   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR
 261        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND
 262       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR
 263        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs
 264     return TypeInt::make(lo,hi,MAX2(r0->_widen,r1->_widen));
 265   else                          // Overflow; assume all integers
 266     return TypeInt::INT;
 267 }
 268 
 269 //=============================================================================
 270 //------------------------------Ideal------------------------------------------
 271 Node *SubLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 272   Node *in1 = in(1);
 273   Node *in2 = in(2);
 274   uint op1 = in1->Opcode();
 275   uint op2 = in2->Opcode();
 276 
 277 #ifdef ASSERT
 278   // Check for dead loop
 279   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||
 280       ( op1 == Op_AddL || op1 == Op_SubL ) &&
 281       ( phase->eqv( in1->in(1), this ) || phase->eqv( in1->in(2), this ) ||
 282         phase->eqv( in1->in(1), in1  ) || phase->eqv( in1->in(2), in1  ) ) )
 283     assert(false, "dead loop in SubLNode::Ideal");
 284 #endif
 285 
 286   if( phase->type( in2 ) == Type::TOP ) return NULL;
 287   const TypeLong *i = phase->type( in2 )->isa_long();
 288   // Convert "x-c0" into "x+ -c0".
 289   if( i &&                      // Might be bottom or top...
 290       i->is_con() )
 291     return new AddLNode(in1, phase->longcon(-i->get_con()));
 292 
 293   // Convert "(x+c0) - y" into (x-y) + c0"
 294   // Do not collapse (x+c0)-y if "+" is a loop increment or
 295   // if "y" is a loop induction variable.
 296   if( op1 == Op_AddL && ok_to_convert(in1, in2) ) {
 297     Node *in11 = in1->in(1);
 298     const Type *tadd = phase->type( in1->in(2) );
 299     if( tadd->singleton() && tadd != Type::TOP ) {
 300       Node *sub2 = phase->transform( new SubLNode( in11, in2 ));
 301       return new AddLNode( sub2, in1->in(2) );
 302     }
 303   }
 304 
 305   // Convert "x - (y+c0)" into "(x-y) - c0"
 306   // Need the same check as in above optimization but reversed.
 307   if (op2 == Op_AddL && ok_to_convert(in2, in1)) {
 308     Node* in21 = in2->in(1);
 309     Node* in22 = in2->in(2);
 310     const TypeLong* tcon = phase->type(in22)->isa_long();
 311     if (tcon != NULL && tcon->is_con()) {
 312       Node* sub2 = phase->transform( new SubLNode(in1, in21) );
 313       Node* neg_c0 = phase->longcon(- tcon->get_con());
 314       return new AddLNode(sub2, neg_c0);
 315     }
 316   }
 317 
 318   const Type *t1 = phase->type( in1 );
 319   if( t1 == Type::TOP ) return NULL;
 320 
 321 #ifdef ASSERT
 322   // Check for dead loop
 323   if( ( op2 == Op_AddL || op2 == Op_SubL ) &&
 324       ( phase->eqv( in2->in(1), this ) || phase->eqv( in2->in(2), this ) ||
 325         phase->eqv( in2->in(1), in2  ) || phase->eqv( in2->in(2), in2  ) ) )
 326     assert(false, "dead loop in SubLNode::Ideal");
 327 #endif
 328 
 329   // Convert "x - (x+y)" into "-y"
 330   if( op2 == Op_AddL &&
 331       phase->eqv( in1, in2->in(1) ) )
 332     return new SubLNode( phase->makecon(TypeLong::ZERO), in2->in(2));
 333   // Convert "x - (y+x)" into "-y"
 334   if( op2 == Op_AddL &&
 335       phase->eqv( in1, in2->in(2) ) )
 336     return new SubLNode( phase->makecon(TypeLong::ZERO),in2->in(1));
 337 
 338   // Convert "0 - (x-y)" into "y-x"
 339   if( phase->type( in1 ) == TypeLong::ZERO && op2 == Op_SubL )
 340     return new SubLNode( in2->in(2), in2->in(1) );
 341 
 342   // Convert "(X+A) - (X+B)" into "A - B"
 343   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(1) == in2->in(1) )
 344     return new SubLNode( in1->in(2), in2->in(2) );
 345 
 346   // Convert "(A+X) - (B+X)" into "A - B"
 347   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(2) == in2->in(2) )
 348     return new SubLNode( in1->in(1), in2->in(1) );
 349 
 350   // Convert "A-(B-C)" into (A+C)-B"
 351   if( op2 == Op_SubL && in2->outcnt() == 1) {
 352     Node *add1 = phase->transform( new AddLNode( in1, in2->in(2) ) );
 353     return new SubLNode( add1, in2->in(1) );
 354   }
 355 
 356   return NULL;
 357 }
 358 
 359 //------------------------------sub--------------------------------------------
 360 // A subtract node differences it's two inputs.
 361 const Type *SubLNode::sub( const Type *t1, const Type *t2 ) const {
 362   const TypeLong *r0 = t1->is_long(); // Handy access
 363   const TypeLong *r1 = t2->is_long();
 364   jlong lo = r0->_lo - r1->_hi;
 365   jlong hi = r0->_hi - r1->_lo;
 366 
 367   // We next check for 32-bit overflow.
 368   // If that happens, we just assume all integers are possible.
 369   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR
 370        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND
 371       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR
 372        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs
 373     return TypeLong::make(lo,hi,MAX2(r0->_widen,r1->_widen));
 374   else                          // Overflow; assume all integers
 375     return TypeLong::LONG;
 376 }
 377 
 378 //=============================================================================
 379 //------------------------------Value------------------------------------------
 380 // A subtract node differences its two inputs.
 381 const Type *SubFPNode::Value( PhaseTransform *phase ) const {
 382   const Node* in1 = in(1);
 383   const Node* in2 = in(2);
 384   // Either input is TOP ==> the result is TOP
 385   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
 386   if( t1 == Type::TOP ) return Type::TOP;
 387   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
 388   if( t2 == Type::TOP ) return Type::TOP;
 389 
 390   // if both operands are infinity of same sign, the result is NaN; do
 391   // not replace with zero
 392   if( (t1->is_finite() && t2->is_finite()) ) {
 393     if( phase->eqv(in1, in2) ) return add_id();
 394   }
 395 
 396   // Either input is BOTTOM ==> the result is the local BOTTOM
 397   const Type *bot = bottom_type();
 398   if( (t1 == bot) || (t2 == bot) ||
 399       (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )
 400     return bot;
 401 
 402   return sub(t1,t2);            // Local flavor of type subtraction
 403 }
 404 
 405 
 406 //=============================================================================
 407 //------------------------------Ideal------------------------------------------
 408 Node *SubFNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 409   const Type *t2 = phase->type( in(2) );
 410   // Convert "x-c0" into "x+ -c0".
 411   if( t2->base() == Type::FloatCon ) {  // Might be bottom or top...
 412     // return new (phase->C, 3) AddFNode(in(1), phase->makecon( TypeF::make(-t2->getf()) ) );
 413   }
 414 
 415   // Not associative because of boundary conditions (infinity)
 416   if( IdealizedNumerics && !phase->C->method()->is_strict() ) {
 417     // Convert "x - (x+y)" into "-y"
 418     if( in(2)->is_Add() &&
 419         phase->eqv(in(1),in(2)->in(1) ) )
 420       return new SubFNode( phase->makecon(TypeF::ZERO),in(2)->in(2));
 421   }
 422 
 423   // Cannot replace 0.0-X with -X because a 'fsub' bytecode computes
 424   // 0.0-0.0 as +0.0, while a 'fneg' bytecode computes -0.0.
 425   //if( phase->type(in(1)) == TypeF::ZERO )
 426   //return new (phase->C, 2) NegFNode(in(2));
 427 
 428   return NULL;
 429 }
 430 
 431 //------------------------------sub--------------------------------------------
 432 // A subtract node differences its two inputs.
 433 const Type *SubFNode::sub( const Type *t1, const Type *t2 ) const {
 434   // no folding if one of operands is infinity or NaN, do not do constant folding
 435   if( g_isfinite(t1->getf()) && g_isfinite(t2->getf()) ) {
 436     return TypeF::make( t1->getf() - t2->getf() );
 437   }
 438   else if( g_isnan(t1->getf()) ) {
 439     return t1;
 440   }
 441   else if( g_isnan(t2->getf()) ) {
 442     return t2;
 443   }
 444   else {
 445     return Type::FLOAT;
 446   }
 447 }
 448 
 449 //=============================================================================
 450 //------------------------------Ideal------------------------------------------
 451 Node *SubDNode::Ideal(PhaseGVN *phase, bool can_reshape){
 452   const Type *t2 = phase->type( in(2) );
 453   // Convert "x-c0" into "x+ -c0".
 454   if( t2->base() == Type::DoubleCon ) { // Might be bottom or top...
 455     // return new (phase->C, 3) AddDNode(in(1), phase->makecon( TypeD::make(-t2->getd()) ) );
 456   }
 457 
 458   // Not associative because of boundary conditions (infinity)
 459   if( IdealizedNumerics && !phase->C->method()->is_strict() ) {
 460     // Convert "x - (x+y)" into "-y"
 461     if( in(2)->is_Add() &&
 462         phase->eqv(in(1),in(2)->in(1) ) )
 463       return new SubDNode( phase->makecon(TypeD::ZERO),in(2)->in(2));
 464   }
 465 
 466   // Cannot replace 0.0-X with -X because a 'dsub' bytecode computes
 467   // 0.0-0.0 as +0.0, while a 'dneg' bytecode computes -0.0.
 468   //if( phase->type(in(1)) == TypeD::ZERO )
 469   //return new (phase->C, 2) NegDNode(in(2));
 470 
 471   return NULL;
 472 }
 473 
 474 //------------------------------sub--------------------------------------------
 475 // A subtract node differences its two inputs.
 476 const Type *SubDNode::sub( const Type *t1, const Type *t2 ) const {
 477   // no folding if one of operands is infinity or NaN, do not do constant folding
 478   if( g_isfinite(t1->getd()) && g_isfinite(t2->getd()) ) {
 479     return TypeD::make( t1->getd() - t2->getd() );
 480   }
 481   else if( g_isnan(t1->getd()) ) {
 482     return t1;
 483   }
 484   else if( g_isnan(t2->getd()) ) {
 485     return t2;
 486   }
 487   else {
 488     return Type::DOUBLE;
 489   }
 490 }
 491 
 492 //=============================================================================
 493 //------------------------------Idealize---------------------------------------
 494 // Unlike SubNodes, compare must still flatten return value to the
 495 // range -1, 0, 1.
 496 // And optimizations like those for (X + Y) - X fail if overflow happens.
 497 Node *CmpNode::Identity( PhaseTransform *phase ) {
 498   return this;
 499 }
 500 
 501 //=============================================================================
 502 //------------------------------cmp--------------------------------------------
 503 // Simplify a CmpI (compare 2 integers) node, based on local information.
 504 // If both inputs are constants, compare them.
 505 const Type *CmpINode::sub( const Type *t1, const Type *t2 ) const {
 506   const TypeInt *r0 = t1->is_int(); // Handy access
 507   const TypeInt *r1 = t2->is_int();
 508 
 509   if( r0->_hi < r1->_lo )       // Range is always low?
 510     return TypeInt::CC_LT;
 511   else if( r0->_lo > r1->_hi )  // Range is always high?
 512     return TypeInt::CC_GT;
 513 
 514   else if( r0->is_con() && r1->is_con() ) { // comparing constants?
 515     assert(r0->get_con() == r1->get_con(), "must be equal");
 516     return TypeInt::CC_EQ;      // Equal results.
 517   } else if( r0->_hi == r1->_lo ) // Range is never high?
 518     return TypeInt::CC_LE;
 519   else if( r0->_lo == r1->_hi ) // Range is never low?
 520     return TypeInt::CC_GE;
 521   return TypeInt::CC;           // else use worst case results
 522 }
 523 
 524 // Simplify a CmpU (compare 2 integers) node, based on local information.
 525 // If both inputs are constants, compare them.
 526 const Type *CmpUNode::sub( const Type *t1, const Type *t2 ) const {
 527   assert(!t1->isa_ptr(), "obsolete usage of CmpU");
 528 
 529   // comparing two unsigned ints
 530   const TypeInt *r0 = t1->is_int();   // Handy access
 531   const TypeInt *r1 = t2->is_int();
 532 
 533   // Current installed version
 534   // Compare ranges for non-overlap
 535   juint lo0 = r0->_lo;
 536   juint hi0 = r0->_hi;
 537   juint lo1 = r1->_lo;
 538   juint hi1 = r1->_hi;
 539 
 540   // If either one has both negative and positive values,
 541   // it therefore contains both 0 and -1, and since [0..-1] is the
 542   // full unsigned range, the type must act as an unsigned bottom.
 543   bool bot0 = ((jint)(lo0 ^ hi0) < 0);
 544   bool bot1 = ((jint)(lo1 ^ hi1) < 0);
 545 
 546   if (bot0 || bot1) {
 547     // All unsigned values are LE -1 and GE 0.
 548     if (lo0 == 0 && hi0 == 0) {
 549       return TypeInt::CC_LE;            //   0 <= bot
 550     } else if (lo1 == 0 && hi1 == 0) {
 551       return TypeInt::CC_GE;            // bot >= 0
 552     }
 553   } else {
 554     // We can use ranges of the form [lo..hi] if signs are the same.
 555     assert(lo0 <= hi0 && lo1 <= hi1, "unsigned ranges are valid");
 556     // results are reversed, '-' > '+' for unsigned compare
 557     if (hi0 < lo1) {
 558       return TypeInt::CC_LT;            // smaller
 559     } else if (lo0 > hi1) {
 560       return TypeInt::CC_GT;            // greater
 561     } else if (hi0 == lo1 && lo0 == hi1) {
 562       return TypeInt::CC_EQ;            // Equal results
 563     } else if (lo0 >= hi1) {
 564       return TypeInt::CC_GE;
 565     } else if (hi0 <= lo1) {
 566       // Check for special case in Hashtable::get.  (See below.)
 567       if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 568         return TypeInt::CC_LT;
 569       return TypeInt::CC_LE;
 570     }
 571   }
 572   // Check for special case in Hashtable::get - the hash index is
 573   // mod'ed to the table size so the following range check is useless.
 574   // Check for: (X Mod Y) CmpU Y, where the mod result and Y both have
 575   // to be positive.
 576   // (This is a gross hack, since the sub method never
 577   // looks at the structure of the node in any other case.)
 578   if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 579     return TypeInt::CC_LT;
 580   return TypeInt::CC;                   // else use worst case results
 581 }
 582 
 583 const Type* CmpUNode::Value(PhaseTransform *phase) const {
 584   const Type* t = SubNode::Value_common(phase);
 585   if (t != NULL) {
 586     return t;
 587   }
 588   const Node* in1 = in(1);
 589   const Node* in2 = in(2);
 590   const Type* t1 = phase->type(in1);
 591   const Type* t2 = phase->type(in2);
 592   assert(t1->isa_int(), "CmpU has only Int type inputs");
 593   if (t2 == TypeInt::INT) { // Compare to bottom?
 594     return bottom_type();
 595   }
 596   uint in1_op = in1->Opcode();
 597   if (in1_op == Op_AddI || in1_op == Op_SubI) {
 598     // The problem rise when result of AddI(SubI) may overflow
 599     // signed integer value. Let say the input type is
 600     // [256, maxint] then +128 will create 2 ranges due to
 601     // overflow: [minint, minint+127] and [384, maxint].
 602     // But C2 type system keep only 1 type range and as result
 603     // it use general [minint, maxint] for this case which we
 604     // can't optimize.
 605     //
 606     // Make 2 separate type ranges based on types of AddI(SubI) inputs
 607     // and compare results of their compare. If results are the same
 608     // CmpU node can be optimized.
 609     const Node* in11 = in1->in(1);
 610     const Node* in12 = in1->in(2);
 611     const Type* t11 = (in11 == in1) ? Type::TOP : phase->type(in11);
 612     const Type* t12 = (in12 == in1) ? Type::TOP : phase->type(in12);
 613     // Skip cases when input types are top or bottom.
 614     if ((t11 != Type::TOP) && (t11 != TypeInt::INT) &&
 615         (t12 != Type::TOP) && (t12 != TypeInt::INT)) {
 616       const TypeInt *r0 = t11->is_int();
 617       const TypeInt *r1 = t12->is_int();
 618       jlong lo_r0 = r0->_lo;
 619       jlong hi_r0 = r0->_hi;
 620       jlong lo_r1 = r1->_lo;
 621       jlong hi_r1 = r1->_hi;
 622       if (in1_op == Op_SubI) {
 623         jlong tmp = hi_r1;
 624         hi_r1 = -lo_r1;
 625         lo_r1 = -tmp;
 626         // Note, for substructing [minint,x] type range
 627         // long arithmetic provides correct overflow answer.
 628         // The confusion come from the fact that in 32-bit
 629         // -minint == minint but in 64-bit -minint == maxint+1.
 630       }
 631       jlong lo_long = lo_r0 + lo_r1;
 632       jlong hi_long = hi_r0 + hi_r1;
 633       int lo_tr1 = min_jint;
 634       int hi_tr1 = (int)hi_long;
 635       int lo_tr2 = (int)lo_long;
 636       int hi_tr2 = max_jint;
 637       bool underflow = lo_long != (jlong)lo_tr2;
 638       bool overflow  = hi_long != (jlong)hi_tr1;
 639       // Use sub(t1, t2) when there is no overflow (one type range)
 640       // or when both overflow and underflow (too complex).
 641       if ((underflow != overflow) && (hi_tr1 < lo_tr2)) {
 642         // Overflow only on one boundary, compare 2 separate type ranges.
 643         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
 644         const TypeInt* tr1 = TypeInt::make(lo_tr1, hi_tr1, w);
 645         const TypeInt* tr2 = TypeInt::make(lo_tr2, hi_tr2, w);
 646         const Type* cmp1 = sub(tr1, t2);
 647         const Type* cmp2 = sub(tr2, t2);
 648         if (cmp1 == cmp2) {
 649           return cmp1; // Hit!
 650         }
 651       }
 652     }
 653   }
 654 
 655   return sub(t1, t2);            // Local flavor of type subtraction
 656 }
 657 
 658 bool CmpUNode::is_index_range_check() const {
 659   // Check for the "(X ModI Y) CmpU Y" shape
 660   return (in(1)->Opcode() == Op_ModI &&
 661           in(1)->in(2)->eqv_uncast(in(2)));
 662 }
 663 
 664 //------------------------------Idealize---------------------------------------
 665 Node *CmpINode::Ideal( PhaseGVN *phase, bool can_reshape ) {
 666   if (phase->type(in(2))->higher_equal(TypeInt::ZERO)) {
 667     switch (in(1)->Opcode()) {
 668     case Op_CmpL3:              // Collapse a CmpL3/CmpI into a CmpL
 669       return new CmpLNode(in(1)->in(1),in(1)->in(2));
 670     case Op_CmpF3:              // Collapse a CmpF3/CmpI into a CmpF
 671       return new CmpFNode(in(1)->in(1),in(1)->in(2));
 672     case Op_CmpD3:              // Collapse a CmpD3/CmpI into a CmpD
 673       return new CmpDNode(in(1)->in(1),in(1)->in(2));
 674     //case Op_SubI:
 675       // If (x - y) cannot overflow, then ((x - y) <?> 0)
 676       // can be turned into (x <?> y).
 677       // This is handled (with more general cases) by Ideal_sub_algebra.
 678     }
 679   }
 680   return NULL;                  // No change
 681 }
 682 
 683 
 684 //=============================================================================
 685 // Simplify a CmpL (compare 2 longs ) node, based on local information.
 686 // If both inputs are constants, compare them.
 687 const Type *CmpLNode::sub( const Type *t1, const Type *t2 ) const {
 688   const TypeLong *r0 = t1->is_long(); // Handy access
 689   const TypeLong *r1 = t2->is_long();
 690 
 691   if( r0->_hi < r1->_lo )       // Range is always low?
 692     return TypeInt::CC_LT;
 693   else if( r0->_lo > r1->_hi )  // Range is always high?
 694     return TypeInt::CC_GT;
 695 
 696   else if( r0->is_con() && r1->is_con() ) { // comparing constants?
 697     assert(r0->get_con() == r1->get_con(), "must be equal");
 698     return TypeInt::CC_EQ;      // Equal results.
 699   } else if( r0->_hi == r1->_lo ) // Range is never high?
 700     return TypeInt::CC_LE;
 701   else if( r0->_lo == r1->_hi ) // Range is never low?
 702     return TypeInt::CC_GE;
 703   return TypeInt::CC;           // else use worst case results
 704 }
 705 
 706 //=============================================================================
 707 //------------------------------sub--------------------------------------------
 708 // Simplify an CmpP (compare 2 pointers) node, based on local information.
 709 // If both inputs are constants, compare them.
 710 const Type *CmpPNode::sub( const Type *t1, const Type *t2 ) const {
 711   const TypePtr *r0 = t1->is_ptr(); // Handy access
 712   const TypePtr *r1 = t2->is_ptr();
 713 
 714   // Undefined inputs makes for an undefined result
 715   if( TypePtr::above_centerline(r0->_ptr) ||
 716       TypePtr::above_centerline(r1->_ptr) )
 717     return Type::TOP;
 718 
 719   if (r0 == r1 && r0->singleton()) {
 720     // Equal pointer constants (klasses, nulls, etc.)
 721     return TypeInt::CC_EQ;
 722   }
 723 
 724   // See if it is 2 unrelated classes.
 725   const TypeOopPtr* p0 = r0->isa_oopptr();
 726   const TypeOopPtr* p1 = r1->isa_oopptr();
 727   if (p0 && p1) {
 728     Node* in1 = in(1)->uncast();
 729     Node* in2 = in(2)->uncast();
 730     AllocateNode* alloc1 = AllocateNode::Ideal_allocation(in1, NULL);
 731     AllocateNode* alloc2 = AllocateNode::Ideal_allocation(in2, NULL);
 732     if (MemNode::detect_ptr_independence(in1, alloc1, in2, alloc2, NULL)) {
 733       return TypeInt::CC_GT;  // different pointers
 734     }
 735     ciKlass* klass0 = p0->klass();
 736     bool    xklass0 = p0->klass_is_exact();
 737     ciKlass* klass1 = p1->klass();
 738     bool    xklass1 = p1->klass_is_exact();
 739     int kps = (p0->isa_klassptr()?1:0) + (p1->isa_klassptr()?1:0);
 740     if (klass0 && klass1 &&
 741         kps != 1 &&             // both or neither are klass pointers
 742         klass0->is_loaded() && !klass0->is_interface() && // do not trust interfaces
 743         klass1->is_loaded() && !klass1->is_interface() &&
 744         (!klass0->is_obj_array_klass() ||
 745          !klass0->as_obj_array_klass()->base_element_klass()->is_interface()) &&
 746         (!klass1->is_obj_array_klass() ||
 747          !klass1->as_obj_array_klass()->base_element_klass()->is_interface())) {
 748       bool unrelated_classes = false;
 749       // See if neither subclasses the other, or if the class on top
 750       // is precise.  In either of these cases, the compare is known
 751       // to fail if at least one of the pointers is provably not null.
 752       if (klass0->equals(klass1)) {  // if types are unequal but klasses are equal
 753         // Do nothing; we know nothing for imprecise types
 754       } else if (klass0->is_subtype_of(klass1)) {
 755         // If klass1's type is PRECISE, then classes are unrelated.
 756         unrelated_classes = xklass1;
 757       } else if (klass1->is_subtype_of(klass0)) {
 758         // If klass0's type is PRECISE, then classes are unrelated.
 759         unrelated_classes = xklass0;
 760       } else {                  // Neither subtypes the other
 761         unrelated_classes = true;
 762       }
 763       if (unrelated_classes) {
 764         // The oops classes are known to be unrelated. If the joined PTRs of
 765         // two oops is not Null and not Bottom, then we are sure that one
 766         // of the two oops is non-null, and the comparison will always fail.
 767         TypePtr::PTR jp = r0->join_ptr(r1->_ptr);
 768         if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
 769           return TypeInt::CC_GT;
 770         }
 771       }
 772     }
 773   }
 774 
 775   // Known constants can be compared exactly
 776   // Null can be distinguished from any NotNull pointers
 777   // Unknown inputs makes an unknown result
 778   if( r0->singleton() ) {
 779     intptr_t bits0 = r0->get_con();
 780     if( r1->singleton() )
 781       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;
 782     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 783   } else if( r1->singleton() ) {
 784     intptr_t bits1 = r1->get_con();
 785     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 786   } else
 787     return TypeInt::CC;
 788 }
 789 
 790 static inline Node* isa_java_mirror_load(PhaseGVN* phase, Node* n) {
 791   // Return the klass node for
 792   //   LoadP(AddP(foo:Klass, #java_mirror))
 793   //   or NULL if not matching.
 794   if (n->Opcode() != Op_LoadP) return NULL;
 795 
 796   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
 797   if (!tp || tp->klass() != phase->C->env()->Class_klass()) return NULL;
 798 
 799   Node* adr = n->in(MemNode::Address);
 800   intptr_t off = 0;
 801   Node* k = AddPNode::Ideal_base_and_offset(adr, phase, off);
 802   if (k == NULL)  return NULL;
 803   const TypeKlassPtr* tkp = phase->type(k)->isa_klassptr();
 804   if (!tkp || off != in_bytes(Klass::java_mirror_offset())) return NULL;
 805 
 806   // We've found the klass node of a Java mirror load.
 807   return k;
 808 }
 809 
 810 static inline Node* isa_const_java_mirror(PhaseGVN* phase, Node* n) {
 811   // for ConP(Foo.class) return ConP(Foo.klass)
 812   // otherwise return NULL
 813   if (!n->is_Con()) return NULL;
 814 
 815   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
 816   if (!tp) return NULL;
 817 
 818   ciType* mirror_type = tp->java_mirror_type();
 819   // TypeInstPtr::java_mirror_type() returns non-NULL for compile-
 820   // time Class constants only.
 821   if (!mirror_type) return NULL;
 822 
 823   // x.getClass() == int.class can never be true (for all primitive types)
 824   // Return a ConP(NULL) node for this case.
 825   if (mirror_type->is_classless()) {
 826     return phase->makecon(TypePtr::NULL_PTR);
 827   }
 828 
 829   // return the ConP(Foo.klass)
 830   assert(mirror_type->is_klass(), "mirror_type should represent a Klass*");
 831   return phase->makecon(TypeKlassPtr::make(mirror_type->as_klass()));
 832 }
 833 
 834 //------------------------------Ideal------------------------------------------
 835 // Normalize comparisons between Java mirror loads to compare the klass instead.
 836 //
 837 // Also check for the case of comparing an unknown klass loaded from the primary
 838 // super-type array vs a known klass with no subtypes.  This amounts to
 839 // checking to see an unknown klass subtypes a known klass with no subtypes;
 840 // this only happens on an exact match.  We can shorten this test by 1 load.
 841 Node *CmpPNode::Ideal( PhaseGVN *phase, bool can_reshape ) {
 842   // Normalize comparisons between Java mirrors into comparisons of the low-
 843   // level klass, where a dependent load could be shortened.
 844   //
 845   // The new pattern has a nice effect of matching the same pattern used in the
 846   // fast path of instanceof/checkcast/Class.isInstance(), which allows
 847   // redundant exact type check be optimized away by GVN.
 848   // For example, in
 849   //   if (x.getClass() == Foo.class) {
 850   //     Foo foo = (Foo) x;
 851   //     // ... use a ...
 852   //   }
 853   // a CmpPNode could be shared between if_acmpne and checkcast
 854   {
 855     Node* k1 = isa_java_mirror_load(phase, in(1));
 856     Node* k2 = isa_java_mirror_load(phase, in(2));
 857     Node* conk2 = isa_const_java_mirror(phase, in(2));
 858 
 859     if (k1 && (k2 || conk2)) {
 860       Node* lhs = k1;
 861       Node* rhs = (k2 != NULL) ? k2 : conk2;
 862       this->set_req(1, lhs);
 863       this->set_req(2, rhs);
 864       return this;
 865     }
 866   }
 867 
 868   // Constant pointer on right?
 869   const TypeKlassPtr* t2 = phase->type(in(2))->isa_klassptr();
 870   if (t2 == NULL || !t2->klass_is_exact())
 871     return NULL;
 872   // Get the constant klass we are comparing to.
 873   ciKlass* superklass = t2->klass();
 874 
 875   // Now check for LoadKlass on left.
 876   Node* ldk1 = in(1);
 877   if (ldk1->is_DecodeNKlass()) {
 878     ldk1 = ldk1->in(1);
 879     if (ldk1->Opcode() != Op_LoadNKlass )
 880       return NULL;
 881   } else if (ldk1->Opcode() != Op_LoadKlass )
 882     return NULL;
 883   // Take apart the address of the LoadKlass:
 884   Node* adr1 = ldk1->in(MemNode::Address);
 885   intptr_t con2 = 0;
 886   Node* ldk2 = AddPNode::Ideal_base_and_offset(adr1, phase, con2);
 887   if (ldk2 == NULL)
 888     return NULL;
 889   if (con2 == oopDesc::klass_offset_in_bytes()) {
 890     // We are inspecting an object's concrete class.
 891     // Short-circuit the check if the query is abstract.
 892     if (superklass->is_interface() ||
 893         superklass->is_abstract()) {
 894       // Make it come out always false:
 895       this->set_req(2, phase->makecon(TypePtr::NULL_PTR));
 896       return this;
 897     }
 898   }
 899 
 900   // Check for a LoadKlass from primary supertype array.
 901   // Any nested loadklass from loadklass+con must be from the p.s. array.
 902   if (ldk2->is_DecodeNKlass()) {
 903     // Keep ldk2 as DecodeN since it could be used in CmpP below.
 904     if (ldk2->in(1)->Opcode() != Op_LoadNKlass )
 905       return NULL;
 906   } else if (ldk2->Opcode() != Op_LoadKlass)
 907     return NULL;
 908 
 909   // Verify that we understand the situation
 910   if (con2 != (intptr_t) superklass->super_check_offset())
 911     return NULL;                // Might be element-klass loading from array klass
 912 
 913   // If 'superklass' has no subklasses and is not an interface, then we are
 914   // assured that the only input which will pass the type check is
 915   // 'superklass' itself.
 916   //
 917   // We could be more liberal here, and allow the optimization on interfaces
 918   // which have a single implementor.  This would require us to increase the
 919   // expressiveness of the add_dependency() mechanism.
 920   // %%% Do this after we fix TypeOopPtr:  Deps are expressive enough now.
 921 
 922   // Object arrays must have their base element have no subtypes
 923   while (superklass->is_obj_array_klass()) {
 924     ciType* elem = superklass->as_obj_array_klass()->element_type();
 925     superklass = elem->as_klass();
 926   }
 927   if (superklass->is_instance_klass()) {
 928     ciInstanceKlass* ik = superklass->as_instance_klass();
 929     if (ik->has_subklass() || ik->is_interface())  return NULL;
 930     // Add a dependency if there is a chance that a subclass will be added later.
 931     if (!ik->is_final()) {
 932       phase->C->dependencies()->assert_leaf_type(ik);
 933     }
 934   }
 935 
 936   // Bypass the dependent load, and compare directly
 937   this->set_req(1,ldk2);
 938 
 939   return this;
 940 }
 941 
 942 //=============================================================================
 943 //------------------------------sub--------------------------------------------
 944 // Simplify an CmpN (compare 2 pointers) node, based on local information.
 945 // If both inputs are constants, compare them.
 946 const Type *CmpNNode::sub( const Type *t1, const Type *t2 ) const {
 947   const TypePtr *r0 = t1->make_ptr(); // Handy access
 948   const TypePtr *r1 = t2->make_ptr();
 949 
 950   // Undefined inputs makes for an undefined result
 951   if ((r0 == NULL) || (r1 == NULL) ||
 952       TypePtr::above_centerline(r0->_ptr) ||
 953       TypePtr::above_centerline(r1->_ptr)) {
 954     return Type::TOP;
 955   }
 956   if (r0 == r1 && r0->singleton()) {
 957     // Equal pointer constants (klasses, nulls, etc.)
 958     return TypeInt::CC_EQ;
 959   }
 960 
 961   // See if it is 2 unrelated classes.
 962   const TypeOopPtr* p0 = r0->isa_oopptr();
 963   const TypeOopPtr* p1 = r1->isa_oopptr();
 964   if (p0 && p1) {
 965     ciKlass* klass0 = p0->klass();
 966     bool    xklass0 = p0->klass_is_exact();
 967     ciKlass* klass1 = p1->klass();
 968     bool    xklass1 = p1->klass_is_exact();
 969     int kps = (p0->isa_klassptr()?1:0) + (p1->isa_klassptr()?1:0);
 970     if (klass0 && klass1 &&
 971         kps != 1 &&             // both or neither are klass pointers
 972         !klass0->is_interface() && // do not trust interfaces
 973         !klass1->is_interface()) {
 974       bool unrelated_classes = false;
 975       // See if neither subclasses the other, or if the class on top
 976       // is precise.  In either of these cases, the compare is known
 977       // to fail if at least one of the pointers is provably not null.
 978       if (klass0->equals(klass1)) { // if types are unequal but klasses are equal
 979         // Do nothing; we know nothing for imprecise types
 980       } else if (klass0->is_subtype_of(klass1)) {
 981         // If klass1's type is PRECISE, then classes are unrelated.
 982         unrelated_classes = xklass1;
 983       } else if (klass1->is_subtype_of(klass0)) {
 984         // If klass0's type is PRECISE, then classes are unrelated.
 985         unrelated_classes = xklass0;
 986       } else {                  // Neither subtypes the other
 987         unrelated_classes = true;
 988       }
 989       if (unrelated_classes) {
 990         // The oops classes are known to be unrelated. If the joined PTRs of
 991         // two oops is not Null and not Bottom, then we are sure that one
 992         // of the two oops is non-null, and the comparison will always fail.
 993         TypePtr::PTR jp = r0->join_ptr(r1->_ptr);
 994         if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
 995           return TypeInt::CC_GT;
 996         }
 997       }
 998     }
 999   }
1000 
1001   // Known constants can be compared exactly
1002   // Null can be distinguished from any NotNull pointers
1003   // Unknown inputs makes an unknown result
1004   if( r0->singleton() ) {
1005     intptr_t bits0 = r0->get_con();
1006     if( r1->singleton() )
1007       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;
1008     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;
1009   } else if( r1->singleton() ) {
1010     intptr_t bits1 = r1->get_con();
1011     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;
1012   } else
1013     return TypeInt::CC;
1014 }
1015 
1016 //------------------------------Ideal------------------------------------------
1017 Node *CmpNNode::Ideal( PhaseGVN *phase, bool can_reshape ) {
1018   return NULL;
1019 }
1020 
1021 //=============================================================================
1022 //------------------------------Value------------------------------------------
1023 // Simplify an CmpF (compare 2 floats ) node, based on local information.
1024 // If both inputs are constants, compare them.
1025 const Type *CmpFNode::Value( PhaseTransform *phase ) const {
1026   const Node* in1 = in(1);
1027   const Node* in2 = in(2);
1028   // Either input is TOP ==> the result is TOP
1029   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
1030   if( t1 == Type::TOP ) return Type::TOP;
1031   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
1032   if( t2 == Type::TOP ) return Type::TOP;
1033 
1034   // Not constants?  Don't know squat - even if they are the same
1035   // value!  If they are NaN's they compare to LT instead of EQ.
1036   const TypeF *tf1 = t1->isa_float_constant();
1037   const TypeF *tf2 = t2->isa_float_constant();
1038   if( !tf1 || !tf2 ) return TypeInt::CC;
1039 
1040   // This implements the Java bytecode fcmpl, so unordered returns -1.
1041   if( tf1->is_nan() || tf2->is_nan() )
1042     return TypeInt::CC_LT;
1043 
1044   if( tf1->_f < tf2->_f ) return TypeInt::CC_LT;
1045   if( tf1->_f > tf2->_f ) return TypeInt::CC_GT;
1046   assert( tf1->_f == tf2->_f, "do not understand FP behavior" );
1047   return TypeInt::CC_EQ;
1048 }
1049 
1050 
1051 //=============================================================================
1052 //------------------------------Value------------------------------------------
1053 // Simplify an CmpD (compare 2 doubles ) node, based on local information.
1054 // If both inputs are constants, compare them.
1055 const Type *CmpDNode::Value( PhaseTransform *phase ) const {
1056   const Node* in1 = in(1);
1057   const Node* in2 = in(2);
1058   // Either input is TOP ==> the result is TOP
1059   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);
1060   if( t1 == Type::TOP ) return Type::TOP;
1061   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);
1062   if( t2 == Type::TOP ) return Type::TOP;
1063 
1064   // Not constants?  Don't know squat - even if they are the same
1065   // value!  If they are NaN's they compare to LT instead of EQ.
1066   const TypeD *td1 = t1->isa_double_constant();
1067   const TypeD *td2 = t2->isa_double_constant();
1068   if( !td1 || !td2 ) return TypeInt::CC;
1069 
1070   // This implements the Java bytecode dcmpl, so unordered returns -1.
1071   if( td1->is_nan() || td2->is_nan() )
1072     return TypeInt::CC_LT;
1073 
1074   if( td1->_d < td2->_d ) return TypeInt::CC_LT;
1075   if( td1->_d > td2->_d ) return TypeInt::CC_GT;
1076   assert( td1->_d == td2->_d, "do not understand FP behavior" );
1077   return TypeInt::CC_EQ;
1078 }
1079 
1080 //------------------------------Ideal------------------------------------------
1081 Node *CmpDNode::Ideal(PhaseGVN *phase, bool can_reshape){
1082   // Check if we can change this to a CmpF and remove a ConvD2F operation.
1083   // Change  (CMPD (F2D (float)) (ConD value))
1084   // To      (CMPF      (float)  (ConF value))
1085   // Valid when 'value' does not lose precision as a float.
1086   // Benefits: eliminates conversion, does not require 24-bit mode
1087 
1088   // NaNs prevent commuting operands.  This transform works regardless of the
1089   // order of ConD and ConvF2D inputs by preserving the original order.
1090   int idx_f2d = 1;              // ConvF2D on left side?
1091   if( in(idx_f2d)->Opcode() != Op_ConvF2D )
1092     idx_f2d = 2;                // No, swap to check for reversed args
1093   int idx_con = 3-idx_f2d;      // Check for the constant on other input
1094 
1095   if( ConvertCmpD2CmpF &&
1096       in(idx_f2d)->Opcode() == Op_ConvF2D &&
1097       in(idx_con)->Opcode() == Op_ConD ) {
1098     const TypeD *t2 = in(idx_con)->bottom_type()->is_double_constant();
1099     double t2_value_as_double = t2->_d;
1100     float  t2_value_as_float  = (float)t2_value_as_double;
1101     if( t2_value_as_double == (double)t2_value_as_float ) {
1102       // Test value can be represented as a float
1103       // Eliminate the conversion to double and create new comparison
1104       Node *new_in1 = in(idx_f2d)->in(1);
1105       Node *new_in2 = phase->makecon( TypeF::make(t2_value_as_float) );
1106       if( idx_f2d != 1 ) {      // Must flip args to match original order
1107         Node *tmp = new_in1;
1108         new_in1 = new_in2;
1109         new_in2 = tmp;
1110       }
1111       CmpFNode *new_cmp = (Opcode() == Op_CmpD3)
1112         ? new CmpF3Node( new_in1, new_in2 )
1113         : new CmpFNode ( new_in1, new_in2 ) ;
1114       return new_cmp;           // Changed to CmpFNode
1115     }
1116     // Testing value required the precision of a double
1117   }
1118   return NULL;                  // No change
1119 }
1120 
1121 
1122 //=============================================================================
1123 //------------------------------cc2logical-------------------------------------
1124 // Convert a condition code type to a logical type
1125 const Type *BoolTest::cc2logical( const Type *CC ) const {
1126   if( CC == Type::TOP ) return Type::TOP;
1127   if( CC->base() != Type::Int ) return TypeInt::BOOL; // Bottom or worse
1128   const TypeInt *ti = CC->is_int();
1129   if( ti->is_con() ) {          // Only 1 kind of condition codes set?
1130     // Match low order 2 bits
1131     int tmp = ((ti->get_con()&3) == (_test&3)) ? 1 : 0;
1132     if( _test & 4 ) tmp = 1-tmp;     // Optionally complement result
1133     return TypeInt::make(tmp);       // Boolean result
1134   }
1135 
1136   if( CC == TypeInt::CC_GE ) {
1137     if( _test == ge ) return TypeInt::ONE;
1138     if( _test == lt ) return TypeInt::ZERO;
1139   }
1140   if( CC == TypeInt::CC_LE ) {
1141     if( _test == le ) return TypeInt::ONE;
1142     if( _test == gt ) return TypeInt::ZERO;
1143   }
1144 
1145   return TypeInt::BOOL;
1146 }
1147 
1148 //------------------------------dump_spec-------------------------------------
1149 // Print special per-node info
1150 #ifndef PRODUCT
1151 void BoolTest::dump_on(outputStream *st) const {
1152   const char *msg[] = {"eq","gt","of","lt","ne","le","nof","ge"};
1153   st->print("%s", msg[_test]);
1154 }
1155 #endif
1156 
1157 //=============================================================================
1158 uint BoolNode::hash() const { return (Node::hash() << 3)|(_test._test+1); }
1159 uint BoolNode::size_of() const { return sizeof(BoolNode); }
1160 
1161 //------------------------------operator==-------------------------------------
1162 uint BoolNode::cmp( const Node &n ) const {
1163   const BoolNode *b = (const BoolNode *)&n; // Cast up
1164   return (_test._test == b->_test._test);
1165 }
1166 
1167 //-------------------------------make_predicate--------------------------------
1168 Node* BoolNode::make_predicate(Node* test_value, PhaseGVN* phase) {
1169   if (test_value->is_Con())   return test_value;
1170   if (test_value->is_Bool())  return test_value;
1171   Compile* C = phase->C;
1172   if (test_value->is_CMove() &&
1173       test_value->in(CMoveNode::Condition)->is_Bool()) {
1174     BoolNode*   bol   = test_value->in(CMoveNode::Condition)->as_Bool();
1175     const Type* ftype = phase->type(test_value->in(CMoveNode::IfFalse));
1176     const Type* ttype = phase->type(test_value->in(CMoveNode::IfTrue));
1177     if (ftype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ttype)) {
1178       return bol;
1179     } else if (ttype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ftype)) {
1180       return phase->transform( bol->negate(phase) );
1181     }
1182     // Else fall through.  The CMove gets in the way of the test.
1183     // It should be the case that make_predicate(bol->as_int_value()) == bol.
1184   }
1185   Node* cmp = new CmpINode(test_value, phase->intcon(0));
1186   cmp = phase->transform(cmp);
1187   Node* bol = new BoolNode(cmp, BoolTest::ne);
1188   return phase->transform(bol);
1189 }
1190 
1191 //--------------------------------as_int_value---------------------------------
1192 Node* BoolNode::as_int_value(PhaseGVN* phase) {
1193   // Inverse to make_predicate.  The CMove probably boils down to a Conv2B.
1194   Node* cmov = CMoveNode::make(phase->C, NULL, this,
1195                                phase->intcon(0), phase->intcon(1),
1196                                TypeInt::BOOL);
1197   return phase->transform(cmov);
1198 }
1199 
1200 //----------------------------------negate-------------------------------------
1201 BoolNode* BoolNode::negate(PhaseGVN* phase) {
1202   Compile* C = phase->C;
1203   return new BoolNode(in(1), _test.negate());
1204 }
1205 
1206 
1207 //------------------------------Ideal------------------------------------------
1208 Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1209   // Change "bool tst (cmp con x)" into "bool ~tst (cmp x con)".
1210   // This moves the constant to the right.  Helps value-numbering.
1211   Node *cmp = in(1);
1212   if( !cmp->is_Sub() ) return NULL;
1213   int cop = cmp->Opcode();
1214   if( cop == Op_FastLock || cop == Op_FastUnlock) return NULL;
1215   Node *cmp1 = cmp->in(1);
1216   Node *cmp2 = cmp->in(2);
1217   if( !cmp1 ) return NULL;
1218 
1219   if (_test._test == BoolTest::overflow || _test._test == BoolTest::no_overflow) {
1220     return NULL;
1221   }
1222 
1223   // Constant on left?
1224   Node *con = cmp1;
1225   uint op2 = cmp2->Opcode();
1226   // Move constants to the right of compare's to canonicalize.
1227   // Do not muck with Opaque1 nodes, as this indicates a loop
1228   // guard that cannot change shape.
1229   if( con->is_Con() && !cmp2->is_Con() && op2 != Op_Opaque1 &&
1230       // Because of NaN's, CmpD and CmpF are not commutative
1231       cop != Op_CmpD && cop != Op_CmpF &&
1232       // Protect against swapping inputs to a compare when it is used by a
1233       // counted loop exit, which requires maintaining the loop-limit as in(2)
1234       !is_counted_loop_exit_test() ) {
1235     // Ok, commute the constant to the right of the cmp node.
1236     // Clone the Node, getting a new Node of the same class
1237     cmp = cmp->clone();
1238     // Swap inputs to the clone
1239     cmp->swap_edges(1, 2);
1240     cmp = phase->transform( cmp );
1241     return new BoolNode( cmp, _test.commute() );
1242   }
1243 
1244   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".
1245   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the
1246   // test instead.
1247   int cmp1_op = cmp1->Opcode();
1248   const TypeInt* cmp2_type = phase->type(cmp2)->isa_int();
1249   if (cmp2_type == NULL)  return NULL;
1250   Node* j_xor = cmp1;
1251   if( cmp2_type == TypeInt::ZERO &&
1252       cmp1_op == Op_XorI &&
1253       j_xor->in(1) != j_xor &&          // An xor of itself is dead
1254       phase->type( j_xor->in(1) ) == TypeInt::BOOL &&
1255       phase->type( j_xor->in(2) ) == TypeInt::ONE &&
1256       (_test._test == BoolTest::eq ||
1257        _test._test == BoolTest::ne) ) {
1258     Node *ncmp = phase->transform(new CmpINode(j_xor->in(1),cmp2));
1259     return new BoolNode( ncmp, _test.negate() );
1260   }
1261 
1262   // Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".
1263   // This is a standard idiom for branching on a boolean value.
1264   Node *c2b = cmp1;
1265   if( cmp2_type == TypeInt::ZERO &&
1266       cmp1_op == Op_Conv2B &&
1267       (_test._test == BoolTest::eq ||
1268        _test._test == BoolTest::ne) ) {
1269     Node *ncmp = phase->transform(phase->type(c2b->in(1))->isa_int()
1270        ? (Node*)new CmpINode(c2b->in(1),cmp2)
1271        : (Node*)new CmpPNode(c2b->in(1),phase->makecon(TypePtr::NULL_PTR))
1272     );
1273     return new BoolNode( ncmp, _test._test );
1274   }
1275 
1276   // Comparing a SubI against a zero is equal to comparing the SubI
1277   // arguments directly.  This only works for eq and ne comparisons
1278   // due to possible integer overflow.
1279   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1280         (cop == Op_CmpI) &&
1281         (cmp1->Opcode() == Op_SubI) &&
1282         ( cmp2_type == TypeInt::ZERO ) ) {
1283     Node *ncmp = phase->transform( new CmpINode(cmp1->in(1),cmp1->in(2)));
1284     return new BoolNode( ncmp, _test._test );
1285   }
1286 
1287   // Change (-A vs 0) into (A vs 0) by commuting the test.  Disallow in the
1288   // most general case because negating 0x80000000 does nothing.  Needed for
1289   // the CmpF3/SubI/CmpI idiom.
1290   if( cop == Op_CmpI &&
1291       cmp1->Opcode() == Op_SubI &&
1292       cmp2_type == TypeInt::ZERO &&
1293       phase->type( cmp1->in(1) ) == TypeInt::ZERO &&
1294       phase->type( cmp1->in(2) )->higher_equal(TypeInt::SYMINT) ) {
1295     Node *ncmp = phase->transform( new CmpINode(cmp1->in(2),cmp2));
1296     return new BoolNode( ncmp, _test.commute() );
1297   }
1298 
1299   //  The transformation below is not valid for either signed or unsigned
1300   //  comparisons due to wraparound concerns at MAX_VALUE and MIN_VALUE.
1301   //  This transformation can be resurrected when we are able to
1302   //  make inferences about the range of values being subtracted from
1303   //  (or added to) relative to the wraparound point.
1304   //
1305   //    // Remove +/-1's if possible.
1306   //    // "X <= Y-1" becomes "X <  Y"
1307   //    // "X+1 <= Y" becomes "X <  Y"
1308   //    // "X <  Y+1" becomes "X <= Y"
1309   //    // "X-1 <  Y" becomes "X <= Y"
1310   //    // Do not this to compares off of the counted-loop-end.  These guys are
1311   //    // checking the trip counter and they want to use the post-incremented
1312   //    // counter.  If they use the PRE-incremented counter, then the counter has
1313   //    // to be incremented in a private block on a loop backedge.
1314   //    if( du && du->cnt(this) && du->out(this)[0]->Opcode() == Op_CountedLoopEnd )
1315   //      return NULL;
1316   //  #ifndef PRODUCT
1317   //    // Do not do this in a wash GVN pass during verification.
1318   //    // Gets triggered by too many simple optimizations to be bothered with
1319   //    // re-trying it again and again.
1320   //    if( !phase->allow_progress() ) return NULL;
1321   //  #endif
1322   //    // Not valid for unsigned compare because of corner cases in involving zero.
1323   //    // For example, replacing "X-1 <u Y" with "X <=u Y" fails to throw an
1324   //    // exception in case X is 0 (because 0-1 turns into 4billion unsigned but
1325   //    // "0 <=u Y" is always true).
1326   //    if( cmp->Opcode() == Op_CmpU ) return NULL;
1327   //    int cmp2_op = cmp2->Opcode();
1328   //    if( _test._test == BoolTest::le ) {
1329   //      if( cmp1_op == Op_AddI &&
1330   //          phase->type( cmp1->in(2) ) == TypeInt::ONE )
1331   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::lt );
1332   //      else if( cmp2_op == Op_AddI &&
1333   //         phase->type( cmp2->in(2) ) == TypeInt::MINUS_1 )
1334   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::lt );
1335   //    } else if( _test._test == BoolTest::lt ) {
1336   //      if( cmp1_op == Op_AddI &&
1337   //          phase->type( cmp1->in(2) ) == TypeInt::MINUS_1 )
1338   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::le );
1339   //      else if( cmp2_op == Op_AddI &&
1340   //         phase->type( cmp2->in(2) ) == TypeInt::ONE )
1341   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::le );
1342   //    }
1343 
1344   return NULL;
1345 }
1346 
1347 //------------------------------Value------------------------------------------
1348 // Simplify a Bool (convert condition codes to boolean (1 or 0)) node,
1349 // based on local information.   If the input is constant, do it.
1350 const Type *BoolNode::Value( PhaseTransform *phase ) const {
1351   return _test.cc2logical( phase->type( in(1) ) );
1352 }
1353 
1354 //------------------------------dump_spec--------------------------------------
1355 // Dump special per-node info
1356 #ifndef PRODUCT
1357 void BoolNode::dump_spec(outputStream *st) const {
1358   st->print("[");
1359   _test.dump_on(st);
1360   st->print("]");
1361 }
1362 #endif
1363 
1364 //------------------------------is_counted_loop_exit_test--------------------------------------
1365 // Returns true if node is used by a counted loop node.
1366 bool BoolNode::is_counted_loop_exit_test() {
1367   for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
1368     Node* use = fast_out(i);
1369     if (use->is_CountedLoopEnd()) {
1370       return true;
1371     }
1372   }
1373   return false;
1374 }
1375 
1376 //=============================================================================
1377 //------------------------------Value------------------------------------------
1378 // Compute sqrt
1379 const Type *SqrtDNode::Value( PhaseTransform *phase ) const {
1380   const Type *t1 = phase->type( in(1) );
1381   if( t1 == Type::TOP ) return Type::TOP;
1382   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1383   double d = t1->getd();
1384   if( d < 0.0 ) return Type::DOUBLE;
1385   return TypeD::make( sqrt( d ) );
1386 }
1387 
1388 //=============================================================================
1389 //------------------------------Value------------------------------------------
1390 // Compute cos
1391 const Type *CosDNode::Value( PhaseTransform *phase ) const {
1392   const Type *t1 = phase->type( in(1) );
1393   if( t1 == Type::TOP ) return Type::TOP;
1394   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1395   double d = t1->getd();
1396   return TypeD::make( StubRoutines::intrinsic_cos( d ) );
1397 }
1398 
1399 //=============================================================================
1400 //------------------------------Value------------------------------------------
1401 // Compute sin
1402 const Type *SinDNode::Value( PhaseTransform *phase ) const {
1403   const Type *t1 = phase->type( in(1) );
1404   if( t1 == Type::TOP ) return Type::TOP;
1405   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1406   double d = t1->getd();
1407   return TypeD::make( StubRoutines::intrinsic_sin( d ) );
1408 }
1409 
1410 //=============================================================================
1411 //------------------------------Value------------------------------------------
1412 // Compute tan
1413 const Type *TanDNode::Value( PhaseTransform *phase ) const {
1414   const Type *t1 = phase->type( in(1) );
1415   if( t1 == Type::TOP ) return Type::TOP;
1416   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1417   double d = t1->getd();
1418   return TypeD::make( StubRoutines::intrinsic_tan( d ) );
1419 }
1420 
1421 //=============================================================================
1422 //------------------------------Value------------------------------------------
1423 // Compute log
1424 const Type *LogDNode::Value( PhaseTransform *phase ) const {
1425   const Type *t1 = phase->type( in(1) );
1426   if( t1 == Type::TOP ) return Type::TOP;
1427   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1428   double d = t1->getd();
1429   return TypeD::make( StubRoutines::intrinsic_log( d ) );
1430 }
1431 
1432 //=============================================================================
1433 //------------------------------Value------------------------------------------
1434 // Compute log10
1435 const Type *Log10DNode::Value( PhaseTransform *phase ) const {
1436   const Type *t1 = phase->type( in(1) );
1437   if( t1 == Type::TOP ) return Type::TOP;
1438   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1439   double d = t1->getd();
1440   return TypeD::make( StubRoutines::intrinsic_log10( d ) );
1441 }
1442 
1443 //=============================================================================
1444 //------------------------------Value------------------------------------------
1445 // Compute exp
1446 const Type *ExpDNode::Value( PhaseTransform *phase ) const {
1447   const Type *t1 = phase->type( in(1) );
1448   if( t1 == Type::TOP ) return Type::TOP;
1449   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1450   double d = t1->getd();
1451   return TypeD::make( StubRoutines::intrinsic_exp( d ) );
1452 }
1453 
1454 
1455 //=============================================================================
1456 //------------------------------Value------------------------------------------
1457 // Compute pow
1458 const Type *PowDNode::Value( PhaseTransform *phase ) const {
1459   const Type *t1 = phase->type( in(1) );
1460   if( t1 == Type::TOP ) return Type::TOP;
1461   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;
1462   const Type *t2 = phase->type( in(2) );
1463   if( t2 == Type::TOP ) return Type::TOP;
1464   if( t2->base() != Type::DoubleCon ) return Type::DOUBLE;
1465   double d1 = t1->getd();
1466   double d2 = t2->getd();
1467   return TypeD::make( StubRoutines::intrinsic_pow( d1, d2 ) );
1468 }