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src/share/vm/opto/subnode.cpp

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  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(PhaseGVN* 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


 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 = java_subtract(r0->_lo, r1->_hi);
 256   int32_t hi = java_subtract(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 = java_subtract(r0->_lo, r1->_hi);
 365   jlong hi = java_subtract(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


 611   // (This is a gross hack, since the sub method never
 612   // looks at the structure of the node in any other case.)
 613   if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 614     return TypeInt::CC_LT;
 615   return TypeInt::CC;                   // else use worst case results
 616 }
 617 
 618 const Type* CmpUNode::Value(PhaseGVN* phase) const {
 619   const Type* t = SubNode::Value_common(phase);
 620   if (t != NULL) {
 621     return t;
 622   }
 623   const Node* in1 = in(1);
 624   const Node* in2 = in(2);
 625   const Type* t1 = phase->type(in1);
 626   const Type* t2 = phase->type(in2);
 627   assert(t1->isa_int(), "CmpU has only Int type inputs");
 628   if (t2 == TypeInt::INT) { // Compare to bottom?
 629     return bottom_type();
 630   }
 631   uint in1_op = in1->Opcode();
 632   if (in1_op == Op_AddI || in1_op == Op_SubI) {
 633     // The problem rise when result of AddI(SubI) may overflow
 634     // signed integer value. Let say the input type is
 635     // [256, maxint] then +128 will create 2 ranges due to
 636     // overflow: [minint, minint+127] and [384, maxint].
 637     // But C2 type system keep only 1 type range and as result
 638     // it use general [minint, maxint] for this case which we
 639     // can't optimize.
 640     //
 641     // Make 2 separate type ranges based on types of AddI(SubI) inputs
 642     // and compare results of their compare. If results are the same
 643     // CmpU node can be optimized.
 644     const Node* in11 = in1->in(1);
 645     const Node* in12 = in1->in(2);
 646     const Type* t11 = (in11 == in1) ? Type::TOP : phase->type(in11);
 647     const Type* t12 = (in12 == in1) ? Type::TOP : phase->type(in12);
 648     // Skip cases when input types are top or bottom.
 649     if ((t11 != Type::TOP) && (t11 != TypeInt::INT) &&
 650         (t12 != Type::TOP) && (t12 != TypeInt::INT)) {
 651       const TypeInt *r0 = t11->is_int();
 652       const TypeInt *r1 = t12->is_int();
 653       jlong lo_r0 = r0->_lo;
 654       jlong hi_r0 = r0->_hi;
 655       jlong lo_r1 = r1->_lo;
 656       jlong hi_r1 = r1->_hi;
 657       if (in1_op == Op_SubI) {
 658         jlong tmp = hi_r1;
 659         hi_r1 = -lo_r1;
 660         lo_r1 = -tmp;
 661         // Note, for substructing [minint,x] type range
 662         // long arithmetic provides correct overflow answer.
 663         // The confusion come from the fact that in 32-bit
 664         // -minint == minint but in 64-bit -minint == maxint+1.
 665       }
 666       jlong lo_long = lo_r0 + lo_r1;
 667       jlong hi_long = hi_r0 + hi_r1;
 668       int lo_tr1 = min_jint;
 669       int hi_tr1 = (int)hi_long;
 670       int lo_tr2 = (int)lo_long;
 671       int hi_tr2 = max_jint;
 672       bool underflow = lo_long != (jlong)lo_tr2;
 673       bool overflow  = hi_long != (jlong)hi_tr1;
 674       // Use sub(t1, t2) when there is no overflow (one type range)
 675       // or when both overflow and underflow (too complex).
 676       if ((underflow != overflow) && (hi_tr1 < lo_tr2)) {
 677         // Overflow only on one boundary, compare 2 separate type ranges.
 678         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
 679         const TypeInt* tr1 = TypeInt::make(lo_tr1, hi_tr1, w);
 680         const TypeInt* tr2 = TypeInt::make(lo_tr2, hi_tr2, w);
 681         const Type* cmp1 = sub(tr1, t2);
 682         const Type* cmp2 = sub(tr2, t2);
 683         if (cmp1 == cmp2) {
 684           return cmp1; // Hit!
 685         }
 686       }
 687     }
 688   }
 689 
 690   return sub(t1, t2);            // Local flavor of type subtraction
 691 }
 692 
 693 bool CmpUNode::is_index_range_check() const {
 694   // Check for the "(X ModI Y) CmpU Y" shape
 695   return (in(1)->Opcode() == Op_ModI &&
 696           in(1)->in(2)->eqv_uncast(in(2)));
 697 }
 698 
 699 //------------------------------Idealize---------------------------------------
 700 Node *CmpINode::Ideal( PhaseGVN *phase, bool can_reshape ) {
 701   if (phase->type(in(2))->higher_equal(TypeInt::ZERO)) {
 702     switch (in(1)->Opcode()) {
 703     case Op_CmpL3:              // Collapse a CmpL3/CmpI into a CmpL
 704       return new CmpLNode(in(1)->in(1),in(1)->in(2));
 705     case Op_CmpF3:              // Collapse a CmpF3/CmpI into a CmpF
 706       return new CmpFNode(in(1)->in(1),in(1)->in(2));
 707     case Op_CmpD3:              // Collapse a CmpD3/CmpI into a CmpD
 708       return new CmpDNode(in(1)->in(1),in(1)->in(2));
 709     //case Op_SubI:
 710       // If (x - y) cannot overflow, then ((x - y) <?> 0)
 711       // can be turned into (x <?> y).
 712       // This is handled (with more general cases) by Ideal_sub_algebra.
 713     }
 714   }
 715   return NULL;                  // No change
 716 }
 717 
 718 
 719 //=============================================================================
 720 // Simplify a CmpL (compare 2 longs ) node, based on local information.
 721 // If both inputs are constants, compare them.
 722 const Type *CmpLNode::sub( const Type *t1, const Type *t2 ) const {
 723   const TypeLong *r0 = t1->is_long(); // Handy access
 724   const TypeLong *r1 = t2->is_long();
 725 
 726   if( r0->_hi < r1->_lo )       // Range is always low?
 727     return TypeInt::CC_LT;


 809 
 810   // Known constants can be compared exactly
 811   // Null can be distinguished from any NotNull pointers
 812   // Unknown inputs makes an unknown result
 813   if( r0->singleton() ) {
 814     intptr_t bits0 = r0->get_con();
 815     if( r1->singleton() )
 816       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;
 817     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 818   } else if( r1->singleton() ) {
 819     intptr_t bits1 = r1->get_con();
 820     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 821   } else
 822     return TypeInt::CC;
 823 }
 824 
 825 static inline Node* isa_java_mirror_load(PhaseGVN* phase, Node* n) {
 826   // Return the klass node for
 827   //   LoadP(AddP(foo:Klass, #java_mirror))
 828   //   or NULL if not matching.
 829   if (n->Opcode() != Op_LoadP) return NULL;
 830 
 831   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
 832   if (!tp || tp->klass() != phase->C->env()->Class_klass()) return NULL;
 833 
 834   Node* adr = n->in(MemNode::Address);
 835   intptr_t off = 0;
 836   Node* k = AddPNode::Ideal_base_and_offset(adr, phase, off);
 837   if (k == NULL)  return NULL;
 838   const TypeKlassPtr* tkp = phase->type(k)->isa_klassptr();
 839   if (!tkp || off != in_bytes(Klass::java_mirror_offset())) return NULL;
 840 
 841   // We've found the klass node of a Java mirror load.
 842   return k;
 843 }
 844 
 845 static inline Node* isa_const_java_mirror(PhaseGVN* phase, Node* n) {
 846   // for ConP(Foo.class) return ConP(Foo.klass)
 847   // otherwise return NULL
 848   if (!n->is_Con()) return NULL;
 849 


 894     if (k1 && (k2 || conk2)) {
 895       Node* lhs = k1;
 896       Node* rhs = (k2 != NULL) ? k2 : conk2;
 897       this->set_req(1, lhs);
 898       this->set_req(2, rhs);
 899       return this;
 900     }
 901   }
 902 
 903   // Constant pointer on right?
 904   const TypeKlassPtr* t2 = phase->type(in(2))->isa_klassptr();
 905   if (t2 == NULL || !t2->klass_is_exact())
 906     return NULL;
 907   // Get the constant klass we are comparing to.
 908   ciKlass* superklass = t2->klass();
 909 
 910   // Now check for LoadKlass on left.
 911   Node* ldk1 = in(1);
 912   if (ldk1->is_DecodeNKlass()) {
 913     ldk1 = ldk1->in(1);
 914     if (ldk1->Opcode() != Op_LoadNKlass )
 915       return NULL;
 916   } else if (ldk1->Opcode() != Op_LoadKlass )
 917     return NULL;
 918   // Take apart the address of the LoadKlass:
 919   Node* adr1 = ldk1->in(MemNode::Address);
 920   intptr_t con2 = 0;
 921   Node* ldk2 = AddPNode::Ideal_base_and_offset(adr1, phase, con2);
 922   if (ldk2 == NULL)
 923     return NULL;
 924   if (con2 == oopDesc::klass_offset_in_bytes()) {
 925     // We are inspecting an object's concrete class.
 926     // Short-circuit the check if the query is abstract.
 927     if (superklass->is_interface() ||
 928         superklass->is_abstract()) {
 929       // Make it come out always false:
 930       this->set_req(2, phase->makecon(TypePtr::NULL_PTR));
 931       return this;
 932     }
 933   }
 934 
 935   // Check for a LoadKlass from primary supertype array.
 936   // Any nested loadklass from loadklass+con must be from the p.s. array.
 937   if (ldk2->is_DecodeNKlass()) {
 938     // Keep ldk2 as DecodeN since it could be used in CmpP below.
 939     if (ldk2->in(1)->Opcode() != Op_LoadNKlass )
 940       return NULL;
 941   } else if (ldk2->Opcode() != Op_LoadKlass)
 942     return NULL;
 943 
 944   // Verify that we understand the situation
 945   if (con2 != (intptr_t) superklass->super_check_offset())
 946     return NULL;                // Might be element-klass loading from array klass
 947 
 948   // If 'superklass' has no subklasses and is not an interface, then we are
 949   // assured that the only input which will pass the type check is
 950   // 'superklass' itself.
 951   //
 952   // We could be more liberal here, and allow the optimization on interfaces
 953   // which have a single implementor.  This would require us to increase the
 954   // expressiveness of the add_dependency() mechanism.
 955   // %%% Do this after we fix TypeOopPtr:  Deps are expressive enough now.
 956 
 957   // Object arrays must have their base element have no subtypes
 958   while (superklass->is_obj_array_klass()) {
 959     ciType* elem = superklass->as_obj_array_klass()->element_type();
 960     superklass = elem->as_klass();
 961   }


1106   if( td1->is_nan() || td2->is_nan() )
1107     return TypeInt::CC_LT;
1108 
1109   if( td1->_d < td2->_d ) return TypeInt::CC_LT;
1110   if( td1->_d > td2->_d ) return TypeInt::CC_GT;
1111   assert( td1->_d == td2->_d, "do not understand FP behavior" );
1112   return TypeInt::CC_EQ;
1113 }
1114 
1115 //------------------------------Ideal------------------------------------------
1116 Node *CmpDNode::Ideal(PhaseGVN *phase, bool can_reshape){
1117   // Check if we can change this to a CmpF and remove a ConvD2F operation.
1118   // Change  (CMPD (F2D (float)) (ConD value))
1119   // To      (CMPF      (float)  (ConF value))
1120   // Valid when 'value' does not lose precision as a float.
1121   // Benefits: eliminates conversion, does not require 24-bit mode
1122 
1123   // NaNs prevent commuting operands.  This transform works regardless of the
1124   // order of ConD and ConvF2D inputs by preserving the original order.
1125   int idx_f2d = 1;              // ConvF2D on left side?
1126   if( in(idx_f2d)->Opcode() != Op_ConvF2D )
1127     idx_f2d = 2;                // No, swap to check for reversed args
1128   int idx_con = 3-idx_f2d;      // Check for the constant on other input
1129 
1130   if( ConvertCmpD2CmpF &&
1131       in(idx_f2d)->Opcode() == Op_ConvF2D &&
1132       in(idx_con)->Opcode() == Op_ConD ) {
1133     const TypeD *t2 = in(idx_con)->bottom_type()->is_double_constant();
1134     double t2_value_as_double = t2->_d;
1135     float  t2_value_as_float  = (float)t2_value_as_double;
1136     if( t2_value_as_double == (double)t2_value_as_float ) {
1137       // Test value can be represented as a float
1138       // Eliminate the conversion to double and create new comparison
1139       Node *new_in1 = in(idx_f2d)->in(1);
1140       Node *new_in2 = phase->makecon( TypeF::make(t2_value_as_float) );
1141       if( idx_f2d != 1 ) {      // Must flip args to match original order
1142         Node *tmp = new_in1;
1143         new_in1 = new_in2;
1144         new_in2 = tmp;
1145       }
1146       CmpFNode *new_cmp = (Opcode() == Op_CmpD3)
1147         ? new CmpF3Node( new_in1, new_in2 )
1148         : new CmpFNode ( new_in1, new_in2 ) ;
1149       return new_cmp;           // Changed to CmpFNode
1150     }
1151     // Testing value required the precision of a double
1152   }
1153   return NULL;                  // No change
1154 }
1155 
1156 
1157 //=============================================================================
1158 //------------------------------cc2logical-------------------------------------
1159 // Convert a condition code type to a logical type
1160 const Type *BoolTest::cc2logical( const Type *CC ) const {
1161   if( CC == Type::TOP ) return Type::TOP;
1162   if( CC->base() != Type::Int ) return TypeInt::BOOL; // Bottom or worse
1163   const TypeInt *ti = CC->is_int();
1164   if( ti->is_con() ) {          // Only 1 kind of condition codes set?
1165     // Match low order 2 bits
1166     int tmp = ((ti->get_con()&3) == (_test&3)) ? 1 : 0;


1220   return phase->transform(bol);
1221 }
1222 
1223 //--------------------------------as_int_value---------------------------------
1224 Node* BoolNode::as_int_value(PhaseGVN* phase) {
1225   // Inverse to make_predicate.  The CMove probably boils down to a Conv2B.
1226   Node* cmov = CMoveNode::make(NULL, this,
1227                                phase->intcon(0), phase->intcon(1),
1228                                TypeInt::BOOL);
1229   return phase->transform(cmov);
1230 }
1231 
1232 //----------------------------------negate-------------------------------------
1233 BoolNode* BoolNode::negate(PhaseGVN* phase) {
1234   return new BoolNode(in(1), _test.negate());
1235 }
1236 
1237 // Change "bool eq/ne (cmp (add/sub A B) C)" into false/true if add/sub
1238 // overflows and we can prove that C is not in the two resulting ranges.
1239 // This optimization is similar to the one performed by CmpUNode::Value().
1240 Node* BoolNode::fold_cmpI(PhaseGVN* phase, SubNode* cmp, Node* cmp1, int cmp_op,
1241                           int cmp1_op, const TypeInt* cmp2_type) {
1242   // Only optimize eq/ne integer comparison of add/sub
1243   if((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1244      (cmp_op == Op_CmpI) && (cmp1_op == Op_AddI || cmp1_op == Op_SubI)) {
1245     // Skip cases were inputs of add/sub are not integers or of bottom type
1246     const TypeInt* r0 = phase->type(cmp1->in(1))->isa_int();
1247     const TypeInt* r1 = phase->type(cmp1->in(2))->isa_int();
1248     if ((r0 != NULL) && (r0 != TypeInt::INT) &&
1249         (r1 != NULL) && (r1 != TypeInt::INT) &&
1250         (cmp2_type != TypeInt::INT)) {
1251       // Compute exact (long) type range of add/sub result
1252       jlong lo_long = r0->_lo;
1253       jlong hi_long = r0->_hi;
1254       if (cmp1_op == Op_AddI) {
1255         lo_long += r1->_lo;
1256         hi_long += r1->_hi;
1257       } else {
1258         lo_long -= r1->_hi;
1259         hi_long -= r1->_lo;
1260       }
1261       // Check for over-/underflow by casting to integer
1262       int lo_int = (int)lo_long;
1263       int hi_int = (int)hi_long;
1264       bool underflow = lo_long != (jlong)lo_int;
1265       bool overflow  = hi_long != (jlong)hi_int;
1266       if ((underflow != overflow) && (hi_int < lo_int)) {
1267         // Overflow on one boundary, compute resulting type ranges:
1268         // tr1 [MIN_INT, hi_int] and tr2 [lo_int, MAX_INT]
1269         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
1270         const TypeInt* tr1 = TypeInt::make(min_jint, hi_int, w);
1271         const TypeInt* tr2 = TypeInt::make(lo_int, max_jint, w);
1272         // Compare second input of cmp to both type ranges
1273         const Type* sub_tr1 = cmp->sub(tr1, cmp2_type);
1274         const Type* sub_tr2 = cmp->sub(tr2, cmp2_type);
1275         if (sub_tr1 == TypeInt::CC_LT && sub_tr2 == TypeInt::CC_GT) {
1276           // The result of the add/sub will never equal cmp2. Replace BoolNode
1277           // by false (0) if it tests for equality and by true (1) otherwise.
1278           return ConINode::make((_test._test == BoolTest::eq) ? 0 : 1);
1279         }
1280       }
1281     }
1282   }
1283   return NULL;
1284 }
1285 
1286 //------------------------------Ideal------------------------------------------
1287 Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1288   // Change "bool tst (cmp con x)" into "bool ~tst (cmp x con)".
1289   // This moves the constant to the right.  Helps value-numbering.
1290   Node *cmp = in(1);
1291   if( !cmp->is_Sub() ) return NULL;
1292   int cop = cmp->Opcode();
1293   if( cop == Op_FastLock || cop == Op_FastUnlock) return NULL;
1294   Node *cmp1 = cmp->in(1);
1295   Node *cmp2 = cmp->in(2);
1296   if( !cmp1 ) return NULL;
1297 
1298   if (_test._test == BoolTest::overflow || _test._test == BoolTest::no_overflow) {
1299     return NULL;
1300   }
1301 
1302   // Constant on left?
1303   Node *con = cmp1;
1304   uint op2 = cmp2->Opcode();
1305   // Move constants to the right of compare's to canonicalize.
1306   // Do not muck with Opaque1 nodes, as this indicates a loop
1307   // guard that cannot change shape.
1308   if( con->is_Con() && !cmp2->is_Con() && op2 != Op_Opaque1 &&
1309       // Because of NaN's, CmpD and CmpF are not commutative
1310       cop != Op_CmpD && cop != Op_CmpF &&
1311       // Protect against swapping inputs to a compare when it is used by a
1312       // counted loop exit, which requires maintaining the loop-limit as in(2)
1313       !is_counted_loop_exit_test() ) {
1314     // Ok, commute the constant to the right of the cmp node.
1315     // Clone the Node, getting a new Node of the same class
1316     cmp = cmp->clone();
1317     // Swap inputs to the clone
1318     cmp->swap_edges(1, 2);
1319     cmp = phase->transform( cmp );
1320     return new BoolNode( cmp, _test.commute() );
1321   }
1322 
1323   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".
1324   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the
1325   // test instead.
1326   int cmp1_op = cmp1->Opcode();
1327   const TypeInt* cmp2_type = phase->type(cmp2)->isa_int();
1328   if (cmp2_type == NULL)  return NULL;
1329   Node* j_xor = cmp1;
1330   if( cmp2_type == TypeInt::ZERO &&
1331       cmp1_op == Op_XorI &&
1332       j_xor->in(1) != j_xor &&          // An xor of itself is dead
1333       phase->type( j_xor->in(1) ) == TypeInt::BOOL &&
1334       phase->type( j_xor->in(2) ) == TypeInt::ONE &&
1335       (_test._test == BoolTest::eq ||
1336        _test._test == BoolTest::ne) ) {
1337     Node *ncmp = phase->transform(new CmpINode(j_xor->in(1),cmp2));
1338     return new BoolNode( ncmp, _test.negate() );
1339   }
1340 
1341   // Change ((x & m) u<= m) or ((m & x) u<= m) to always true
1342   // Same with ((x & m) u< m+1) and ((m & x) u< m+1)
1343   if (cop == Op_CmpU &&
1344       cmp1->Opcode() == Op_AndI) {
1345     Node* bound = NULL;
1346     if (_test._test == BoolTest::le) {
1347       bound = cmp2;
1348     } else if (_test._test == BoolTest::lt &&
1349                cmp2->Opcode() == Op_AddI &&
1350                cmp2->in(2)->find_int_con(0) == 1) {
1351       bound = cmp2->in(1);
1352     }
1353     if (cmp1->in(2) == bound || cmp1->in(1) == bound) {
1354       return ConINode::make(1);
1355     }
1356   }
1357 
1358   // Change ((x & (m - 1)) u< m) into (m > 0)
1359   // This is the off-by-one variant of the above
1360   if (cop == Op_CmpU &&
1361       _test._test == BoolTest::lt &&
1362       cmp1->Opcode() == Op_AndI) {
1363     Node* l = cmp1->in(1);
1364     Node* r = cmp1->in(2);
1365     for (int repeat = 0; repeat < 2; repeat++) {
1366       bool match = r->Opcode() == Op_AddI && r->in(2)->find_int_con(0) == -1 &&
1367                    r->in(1) == cmp2;
1368       if (match) {
1369         // arraylength known to be non-negative, so a (arraylength != 0) is sufficient,
1370         // but to be compatible with the array range check pattern, use (arraylength u> 0)
1371         Node* ncmp = cmp2->Opcode() == Op_LoadRange
1372                      ? phase->transform(new CmpUNode(cmp2, phase->intcon(0)))
1373                      : phase->transform(new CmpINode(cmp2, phase->intcon(0)));
1374         return new BoolNode(ncmp, BoolTest::gt);
1375       } else {
1376         // commute and try again
1377         l = cmp1->in(2);
1378         r = cmp1->in(1);
1379       }
1380     }
1381   }
1382 
1383   // Change (arraylength <= 0) or (arraylength == 0)
1384   //   into (arraylength u<= 0)
1385   // Also change (arraylength != 0) into (arraylength u> 0)
1386   // The latter version matches the code pattern generated for
1387   // array range checks, which will more likely be optimized later.
1388   if (cop == Op_CmpI &&
1389       cmp1->Opcode() == Op_LoadRange &&
1390       cmp2->find_int_con(-1) == 0) {
1391     if (_test._test == BoolTest::le || _test._test == BoolTest::eq) {
1392       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1393       return new BoolNode(ncmp, BoolTest::le);
1394     } else if (_test._test == BoolTest::ne) {
1395       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1396       return new BoolNode(ncmp, BoolTest::gt);
1397     }
1398   }
1399 
1400   // Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".
1401   // This is a standard idiom for branching on a boolean value.
1402   Node *c2b = cmp1;
1403   if( cmp2_type == TypeInt::ZERO &&
1404       cmp1_op == Op_Conv2B &&
1405       (_test._test == BoolTest::eq ||
1406        _test._test == BoolTest::ne) ) {
1407     Node *ncmp = phase->transform(phase->type(c2b->in(1))->isa_int()
1408        ? (Node*)new CmpINode(c2b->in(1),cmp2)
1409        : (Node*)new CmpPNode(c2b->in(1),phase->makecon(TypePtr::NULL_PTR))
1410     );
1411     return new BoolNode( ncmp, _test._test );
1412   }
1413 
1414   // Comparing a SubI against a zero is equal to comparing the SubI
1415   // arguments directly.  This only works for eq and ne comparisons
1416   // due to possible integer overflow.
1417   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1418         (cop == Op_CmpI) &&
1419         (cmp1->Opcode() == Op_SubI) &&
1420         ( cmp2_type == TypeInt::ZERO ) ) {
1421     Node *ncmp = phase->transform( new CmpINode(cmp1->in(1),cmp1->in(2)));
1422     return new BoolNode( ncmp, _test._test );
1423   }
1424 
1425   // Change (-A vs 0) into (A vs 0) by commuting the test.  Disallow in the
1426   // most general case because negating 0x80000000 does nothing.  Needed for
1427   // the CmpF3/SubI/CmpI idiom.
1428   if( cop == Op_CmpI &&
1429       cmp1->Opcode() == Op_SubI &&
1430       cmp2_type == TypeInt::ZERO &&
1431       phase->type( cmp1->in(1) ) == TypeInt::ZERO &&
1432       phase->type( cmp1->in(2) )->higher_equal(TypeInt::SYMINT) ) {
1433     Node *ncmp = phase->transform( new CmpINode(cmp1->in(2),cmp2));
1434     return new BoolNode( ncmp, _test.commute() );
1435   }
1436 
1437   // Try to optimize signed integer comparison
1438   return fold_cmpI(phase, cmp->as_Sub(), cmp1, cop, cmp1_op, cmp2_type);
1439 
1440   //  The transformation below is not valid for either signed or unsigned
1441   //  comparisons due to wraparound concerns at MAX_VALUE and MIN_VALUE.
1442   //  This transformation can be resurrected when we are able to
1443   //  make inferences about the range of values being subtracted from
1444   //  (or added to) relative to the wraparound point.
1445   //
1446   //    // Remove +/-1's if possible.
1447   //    // "X <= Y-1" becomes "X <  Y"
1448   //    // "X+1 <= Y" becomes "X <  Y"
1449   //    // "X <  Y+1" becomes "X <= Y"




  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(PhaseGVN* 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() == Opcodes::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() == Opcodes::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


 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   Opcodes op1 = in1->Opcode();
 145   Opcodes op2 = in2->Opcode();
 146 
 147 #ifdef ASSERT
 148   // Check for dead loop
 149   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||
 150       ( op1 == Opcodes::Op_AddI || op1 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::Op_AddI || op2 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::Op_AddI && op2 == Opcodes::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 == Opcodes::Op_AddI && op2 == Opcodes::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 == Opcodes::Op_AddI && op2 == Opcodes::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 == Opcodes::Op_AddI && op2 == Opcodes::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 == Opcodes::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 = java_subtract(r0->_lo, r1->_hi);
 256   int32_t hi = java_subtract(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   Opcodes op1 = in1->Opcode();
 275   Opcodes op2 = in2->Opcode();
 276 
 277 #ifdef ASSERT
 278   // Check for dead loop
 279   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||
 280       ( op1 == Opcodes::Op_AddL || op1 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::Op_AddL || op2 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::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 == Opcodes::Op_AddL && op2 == Opcodes::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 == Opcodes::Op_AddL && op2 == Opcodes::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 == Opcodes::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 = java_subtract(r0->_lo, r1->_hi);
 365   jlong hi = java_subtract(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


 611   // (This is a gross hack, since the sub method never
 612   // looks at the structure of the node in any other case.)
 613   if ((jint)lo0 >= 0 && (jint)lo1 >= 0 && is_index_range_check())
 614     return TypeInt::CC_LT;
 615   return TypeInt::CC;                   // else use worst case results
 616 }
 617 
 618 const Type* CmpUNode::Value(PhaseGVN* phase) const {
 619   const Type* t = SubNode::Value_common(phase);
 620   if (t != NULL) {
 621     return t;
 622   }
 623   const Node* in1 = in(1);
 624   const Node* in2 = in(2);
 625   const Type* t1 = phase->type(in1);
 626   const Type* t2 = phase->type(in2);
 627   assert(t1->isa_int(), "CmpU has only Int type inputs");
 628   if (t2 == TypeInt::INT) { // Compare to bottom?
 629     return bottom_type();
 630   }
 631   Opcodes in1_op = in1->Opcode();
 632   if (in1_op == Opcodes::Op_AddI || in1_op == Opcodes::Op_SubI) {
 633     // The problem rise when result of AddI(SubI) may overflow
 634     // signed integer value. Let say the input type is
 635     // [256, maxint] then +128 will create 2 ranges due to
 636     // overflow: [minint, minint+127] and [384, maxint].
 637     // But C2 type system keep only 1 type range and as result
 638     // it use general [minint, maxint] for this case which we
 639     // can't optimize.
 640     //
 641     // Make 2 separate type ranges based on types of AddI(SubI) inputs
 642     // and compare results of their compare. If results are the same
 643     // CmpU node can be optimized.
 644     const Node* in11 = in1->in(1);
 645     const Node* in12 = in1->in(2);
 646     const Type* t11 = (in11 == in1) ? Type::TOP : phase->type(in11);
 647     const Type* t12 = (in12 == in1) ? Type::TOP : phase->type(in12);
 648     // Skip cases when input types are top or bottom.
 649     if ((t11 != Type::TOP) && (t11 != TypeInt::INT) &&
 650         (t12 != Type::TOP) && (t12 != TypeInt::INT)) {
 651       const TypeInt *r0 = t11->is_int();
 652       const TypeInt *r1 = t12->is_int();
 653       jlong lo_r0 = r0->_lo;
 654       jlong hi_r0 = r0->_hi;
 655       jlong lo_r1 = r1->_lo;
 656       jlong hi_r1 = r1->_hi;
 657       if (in1_op == Opcodes::Op_SubI) {
 658         jlong tmp = hi_r1;
 659         hi_r1 = -lo_r1;
 660         lo_r1 = -tmp;
 661         // Note, for substructing [minint,x] type range
 662         // long arithmetic provides correct overflow answer.
 663         // The confusion come from the fact that in 32-bit
 664         // -minint == minint but in 64-bit -minint == maxint+1.
 665       }
 666       jlong lo_long = lo_r0 + lo_r1;
 667       jlong hi_long = hi_r0 + hi_r1;
 668       int lo_tr1 = min_jint;
 669       int hi_tr1 = (int)hi_long;
 670       int lo_tr2 = (int)lo_long;
 671       int hi_tr2 = max_jint;
 672       bool underflow = lo_long != (jlong)lo_tr2;
 673       bool overflow  = hi_long != (jlong)hi_tr1;
 674       // Use sub(t1, t2) when there is no overflow (one type range)
 675       // or when both overflow and underflow (too complex).
 676       if ((underflow != overflow) && (hi_tr1 < lo_tr2)) {
 677         // Overflow only on one boundary, compare 2 separate type ranges.
 678         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
 679         const TypeInt* tr1 = TypeInt::make(lo_tr1, hi_tr1, w);
 680         const TypeInt* tr2 = TypeInt::make(lo_tr2, hi_tr2, w);
 681         const Type* cmp1 = sub(tr1, t2);
 682         const Type* cmp2 = sub(tr2, t2);
 683         if (cmp1 == cmp2) {
 684           return cmp1; // Hit!
 685         }
 686       }
 687     }
 688   }
 689 
 690   return sub(t1, t2);            // Local flavor of type subtraction
 691 }
 692 
 693 bool CmpUNode::is_index_range_check() const {
 694   // Check for the "(X ModI Y) CmpU Y" shape
 695   return (in(1)->Opcode() == Opcodes::Op_ModI &&
 696           in(1)->in(2)->eqv_uncast(in(2)));
 697 }
 698 
 699 //------------------------------Idealize---------------------------------------
 700 Node *CmpINode::Ideal( PhaseGVN *phase, bool can_reshape ) {
 701   if (phase->type(in(2))->higher_equal(TypeInt::ZERO)) {
 702     switch (in(1)->Opcode()) {
 703     case Opcodes::Op_CmpL3:              // Collapse a CmpL3/CmpI into a CmpL
 704       return new CmpLNode(in(1)->in(1),in(1)->in(2));
 705     case Opcodes::Op_CmpF3:              // Collapse a CmpF3/CmpI into a CmpF
 706       return new CmpFNode(in(1)->in(1),in(1)->in(2));
 707     case Opcodes::Op_CmpD3:              // Collapse a CmpD3/CmpI into a CmpD
 708       return new CmpDNode(in(1)->in(1),in(1)->in(2));
 709     //case Op_SubI:
 710       // If (x - y) cannot overflow, then ((x - y) <?> 0)
 711       // can be turned into (x <?> y).
 712       // This is handled (with more general cases) by Ideal_sub_algebra.
 713     }
 714   }
 715   return NULL;                  // No change
 716 }
 717 
 718 
 719 //=============================================================================
 720 // Simplify a CmpL (compare 2 longs ) node, based on local information.
 721 // If both inputs are constants, compare them.
 722 const Type *CmpLNode::sub( const Type *t1, const Type *t2 ) const {
 723   const TypeLong *r0 = t1->is_long(); // Handy access
 724   const TypeLong *r1 = t2->is_long();
 725 
 726   if( r0->_hi < r1->_lo )       // Range is always low?
 727     return TypeInt::CC_LT;


 809 
 810   // Known constants can be compared exactly
 811   // Null can be distinguished from any NotNull pointers
 812   // Unknown inputs makes an unknown result
 813   if( r0->singleton() ) {
 814     intptr_t bits0 = r0->get_con();
 815     if( r1->singleton() )
 816       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;
 817     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 818   } else if( r1->singleton() ) {
 819     intptr_t bits1 = r1->get_con();
 820     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;
 821   } else
 822     return TypeInt::CC;
 823 }
 824 
 825 static inline Node* isa_java_mirror_load(PhaseGVN* phase, Node* n) {
 826   // Return the klass node for
 827   //   LoadP(AddP(foo:Klass, #java_mirror))
 828   //   or NULL if not matching.
 829   if (n->Opcode() != Opcodes::Op_LoadP) return NULL;
 830 
 831   const TypeInstPtr* tp = phase->type(n)->isa_instptr();
 832   if (!tp || tp->klass() != phase->C->env()->Class_klass()) return NULL;
 833 
 834   Node* adr = n->in(MemNode::Address);
 835   intptr_t off = 0;
 836   Node* k = AddPNode::Ideal_base_and_offset(adr, phase, off);
 837   if (k == NULL)  return NULL;
 838   const TypeKlassPtr* tkp = phase->type(k)->isa_klassptr();
 839   if (!tkp || off != in_bytes(Klass::java_mirror_offset())) return NULL;
 840 
 841   // We've found the klass node of a Java mirror load.
 842   return k;
 843 }
 844 
 845 static inline Node* isa_const_java_mirror(PhaseGVN* phase, Node* n) {
 846   // for ConP(Foo.class) return ConP(Foo.klass)
 847   // otherwise return NULL
 848   if (!n->is_Con()) return NULL;
 849 


 894     if (k1 && (k2 || conk2)) {
 895       Node* lhs = k1;
 896       Node* rhs = (k2 != NULL) ? k2 : conk2;
 897       this->set_req(1, lhs);
 898       this->set_req(2, rhs);
 899       return this;
 900     }
 901   }
 902 
 903   // Constant pointer on right?
 904   const TypeKlassPtr* t2 = phase->type(in(2))->isa_klassptr();
 905   if (t2 == NULL || !t2->klass_is_exact())
 906     return NULL;
 907   // Get the constant klass we are comparing to.
 908   ciKlass* superklass = t2->klass();
 909 
 910   // Now check for LoadKlass on left.
 911   Node* ldk1 = in(1);
 912   if (ldk1->is_DecodeNKlass()) {
 913     ldk1 = ldk1->in(1);
 914     if (ldk1->Opcode() != Opcodes::Op_LoadNKlass )
 915       return NULL;
 916   } else if (ldk1->Opcode() != Opcodes::Op_LoadKlass )
 917     return NULL;
 918   // Take apart the address of the LoadKlass:
 919   Node* adr1 = ldk1->in(MemNode::Address);
 920   intptr_t con2 = 0;
 921   Node* ldk2 = AddPNode::Ideal_base_and_offset(adr1, phase, con2);
 922   if (ldk2 == NULL)
 923     return NULL;
 924   if (con2 == oopDesc::klass_offset_in_bytes()) {
 925     // We are inspecting an object's concrete class.
 926     // Short-circuit the check if the query is abstract.
 927     if (superklass->is_interface() ||
 928         superklass->is_abstract()) {
 929       // Make it come out always false:
 930       this->set_req(2, phase->makecon(TypePtr::NULL_PTR));
 931       return this;
 932     }
 933   }
 934 
 935   // Check for a LoadKlass from primary supertype array.
 936   // Any nested loadklass from loadklass+con must be from the p.s. array.
 937   if (ldk2->is_DecodeNKlass()) {
 938     // Keep ldk2 as DecodeN since it could be used in CmpP below.
 939     if (ldk2->in(1)->Opcode() != Opcodes::Op_LoadNKlass )
 940       return NULL;
 941   } else if (ldk2->Opcode() != Opcodes::Op_LoadKlass)
 942     return NULL;
 943 
 944   // Verify that we understand the situation
 945   if (con2 != (intptr_t) superklass->super_check_offset())
 946     return NULL;                // Might be element-klass loading from array klass
 947 
 948   // If 'superklass' has no subklasses and is not an interface, then we are
 949   // assured that the only input which will pass the type check is
 950   // 'superklass' itself.
 951   //
 952   // We could be more liberal here, and allow the optimization on interfaces
 953   // which have a single implementor.  This would require us to increase the
 954   // expressiveness of the add_dependency() mechanism.
 955   // %%% Do this after we fix TypeOopPtr:  Deps are expressive enough now.
 956 
 957   // Object arrays must have their base element have no subtypes
 958   while (superklass->is_obj_array_klass()) {
 959     ciType* elem = superklass->as_obj_array_klass()->element_type();
 960     superklass = elem->as_klass();
 961   }


1106   if( td1->is_nan() || td2->is_nan() )
1107     return TypeInt::CC_LT;
1108 
1109   if( td1->_d < td2->_d ) return TypeInt::CC_LT;
1110   if( td1->_d > td2->_d ) return TypeInt::CC_GT;
1111   assert( td1->_d == td2->_d, "do not understand FP behavior" );
1112   return TypeInt::CC_EQ;
1113 }
1114 
1115 //------------------------------Ideal------------------------------------------
1116 Node *CmpDNode::Ideal(PhaseGVN *phase, bool can_reshape){
1117   // Check if we can change this to a CmpF and remove a ConvD2F operation.
1118   // Change  (CMPD (F2D (float)) (ConD value))
1119   // To      (CMPF      (float)  (ConF value))
1120   // Valid when 'value' does not lose precision as a float.
1121   // Benefits: eliminates conversion, does not require 24-bit mode
1122 
1123   // NaNs prevent commuting operands.  This transform works regardless of the
1124   // order of ConD and ConvF2D inputs by preserving the original order.
1125   int idx_f2d = 1;              // ConvF2D on left side?
1126   if( in(idx_f2d)->Opcode() != Opcodes::Op_ConvF2D )
1127     idx_f2d = 2;                // No, swap to check for reversed args
1128   int idx_con = 3-idx_f2d;      // Check for the constant on other input
1129 
1130   if( ConvertCmpD2CmpF &&
1131       in(idx_f2d)->Opcode() == Opcodes::Op_ConvF2D &&
1132       in(idx_con)->Opcode() == Opcodes::Op_ConD ) {
1133     const TypeD *t2 = in(idx_con)->bottom_type()->is_double_constant();
1134     double t2_value_as_double = t2->_d;
1135     float  t2_value_as_float  = (float)t2_value_as_double;
1136     if( t2_value_as_double == (double)t2_value_as_float ) {
1137       // Test value can be represented as a float
1138       // Eliminate the conversion to double and create new comparison
1139       Node *new_in1 = in(idx_f2d)->in(1);
1140       Node *new_in2 = phase->makecon( TypeF::make(t2_value_as_float) );
1141       if( idx_f2d != 1 ) {      // Must flip args to match original order
1142         Node *tmp = new_in1;
1143         new_in1 = new_in2;
1144         new_in2 = tmp;
1145       }
1146       CmpFNode *new_cmp = (Opcode() == Opcodes::Op_CmpD3)
1147         ? new CmpF3Node( new_in1, new_in2 )
1148         : new CmpFNode ( new_in1, new_in2 ) ;
1149       return new_cmp;           // Changed to CmpFNode
1150     }
1151     // Testing value required the precision of a double
1152   }
1153   return NULL;                  // No change
1154 }
1155 
1156 
1157 //=============================================================================
1158 //------------------------------cc2logical-------------------------------------
1159 // Convert a condition code type to a logical type
1160 const Type *BoolTest::cc2logical( const Type *CC ) const {
1161   if( CC == Type::TOP ) return Type::TOP;
1162   if( CC->base() != Type::Int ) return TypeInt::BOOL; // Bottom or worse
1163   const TypeInt *ti = CC->is_int();
1164   if( ti->is_con() ) {          // Only 1 kind of condition codes set?
1165     // Match low order 2 bits
1166     int tmp = ((ti->get_con()&3) == (_test&3)) ? 1 : 0;


1220   return phase->transform(bol);
1221 }
1222 
1223 //--------------------------------as_int_value---------------------------------
1224 Node* BoolNode::as_int_value(PhaseGVN* phase) {
1225   // Inverse to make_predicate.  The CMove probably boils down to a Conv2B.
1226   Node* cmov = CMoveNode::make(NULL, this,
1227                                phase->intcon(0), phase->intcon(1),
1228                                TypeInt::BOOL);
1229   return phase->transform(cmov);
1230 }
1231 
1232 //----------------------------------negate-------------------------------------
1233 BoolNode* BoolNode::negate(PhaseGVN* phase) {
1234   return new BoolNode(in(1), _test.negate());
1235 }
1236 
1237 // Change "bool eq/ne (cmp (add/sub A B) C)" into false/true if add/sub
1238 // overflows and we can prove that C is not in the two resulting ranges.
1239 // This optimization is similar to the one performed by CmpUNode::Value().
1240 Node* BoolNode::fold_cmpI(PhaseGVN* phase, SubNode* cmp, Node* cmp1, Opcodes cmp_op,
1241                           Opcodes cmp1_op, const TypeInt* cmp2_type) {
1242   // Only optimize eq/ne integer comparison of add/sub
1243   if((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1244      (cmp_op == Opcodes::Op_CmpI) && (cmp1_op == Opcodes::Op_AddI || cmp1_op == Opcodes::Op_SubI)) {
1245     // Skip cases were inputs of add/sub are not integers or of bottom type
1246     const TypeInt* r0 = phase->type(cmp1->in(1))->isa_int();
1247     const TypeInt* r1 = phase->type(cmp1->in(2))->isa_int();
1248     if ((r0 != NULL) && (r0 != TypeInt::INT) &&
1249         (r1 != NULL) && (r1 != TypeInt::INT) &&
1250         (cmp2_type != TypeInt::INT)) {
1251       // Compute exact (long) type range of add/sub result
1252       jlong lo_long = r0->_lo;
1253       jlong hi_long = r0->_hi;
1254       if (cmp1_op == Opcodes::Op_AddI) {
1255         lo_long += r1->_lo;
1256         hi_long += r1->_hi;
1257       } else {
1258         lo_long -= r1->_hi;
1259         hi_long -= r1->_lo;
1260       }
1261       // Check for over-/underflow by casting to integer
1262       int lo_int = (int)lo_long;
1263       int hi_int = (int)hi_long;
1264       bool underflow = lo_long != (jlong)lo_int;
1265       bool overflow  = hi_long != (jlong)hi_int;
1266       if ((underflow != overflow) && (hi_int < lo_int)) {
1267         // Overflow on one boundary, compute resulting type ranges:
1268         // tr1 [MIN_INT, hi_int] and tr2 [lo_int, MAX_INT]
1269         int w = MAX2(r0->_widen, r1->_widen); // _widen does not matter here
1270         const TypeInt* tr1 = TypeInt::make(min_jint, hi_int, w);
1271         const TypeInt* tr2 = TypeInt::make(lo_int, max_jint, w);
1272         // Compare second input of cmp to both type ranges
1273         const Type* sub_tr1 = cmp->sub(tr1, cmp2_type);
1274         const Type* sub_tr2 = cmp->sub(tr2, cmp2_type);
1275         if (sub_tr1 == TypeInt::CC_LT && sub_tr2 == TypeInt::CC_GT) {
1276           // The result of the add/sub will never equal cmp2. Replace BoolNode
1277           // by false (0) if it tests for equality and by true (1) otherwise.
1278           return ConINode::make((_test._test == BoolTest::eq) ? 0 : 1);
1279         }
1280       }
1281     }
1282   }
1283   return NULL;
1284 }
1285 
1286 //------------------------------Ideal------------------------------------------
1287 Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1288   // Change "bool tst (cmp con x)" into "bool ~tst (cmp x con)".
1289   // This moves the constant to the right.  Helps value-numbering.
1290   Node *cmp = in(1);
1291   if( !cmp->is_Sub() ) return NULL;
1292   Opcodes cop = cmp->Opcode();
1293   if( cop == Opcodes::Op_FastLock || cop == Opcodes::Op_FastUnlock) return NULL;
1294   Node *cmp1 = cmp->in(1);
1295   Node *cmp2 = cmp->in(2);
1296   if( !cmp1 ) return NULL;
1297 
1298   if (_test._test == BoolTest::overflow || _test._test == BoolTest::no_overflow) {
1299     return NULL;
1300   }
1301 
1302   // Constant on left?
1303   Node *con = cmp1;
1304   Opcodes op2 = cmp2->Opcode();
1305   // Move constants to the right of compare's to canonicalize.
1306   // Do not muck with Opaque1 nodes, as this indicates a loop
1307   // guard that cannot change shape.
1308   if( con->is_Con() && !cmp2->is_Con() && op2 != Opcodes::Op_Opaque1 &&
1309       // Because of NaN's, CmpD and CmpF are not commutative
1310       cop != Opcodes::Op_CmpD && cop != Opcodes::Op_CmpF &&
1311       // Protect against swapping inputs to a compare when it is used by a
1312       // counted loop exit, which requires maintaining the loop-limit as in(2)
1313       !is_counted_loop_exit_test() ) {
1314     // Ok, commute the constant to the right of the cmp node.
1315     // Clone the Node, getting a new Node of the same class
1316     cmp = cmp->clone();
1317     // Swap inputs to the clone
1318     cmp->swap_edges(1, 2);
1319     cmp = phase->transform( cmp );
1320     return new BoolNode( cmp, _test.commute() );
1321   }
1322 
1323   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".
1324   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the
1325   // test instead.
1326   Opcodes cmp1_op = cmp1->Opcode();
1327   const TypeInt* cmp2_type = phase->type(cmp2)->isa_int();
1328   if (cmp2_type == NULL)  return NULL;
1329   Node* j_xor = cmp1;
1330   if( cmp2_type == TypeInt::ZERO &&
1331       cmp1_op == Opcodes::Op_XorI &&
1332       j_xor->in(1) != j_xor &&          // An xor of itself is dead
1333       phase->type( j_xor->in(1) ) == TypeInt::BOOL &&
1334       phase->type( j_xor->in(2) ) == TypeInt::ONE &&
1335       (_test._test == BoolTest::eq ||
1336        _test._test == BoolTest::ne) ) {
1337     Node *ncmp = phase->transform(new CmpINode(j_xor->in(1),cmp2));
1338     return new BoolNode( ncmp, _test.negate() );
1339   }
1340 
1341   // Change ((x & m) u<= m) or ((m & x) u<= m) to always true
1342   // Same with ((x & m) u< m+1) and ((m & x) u< m+1)
1343   if (cop == Opcodes::Op_CmpU &&
1344       cmp1->Opcode() == Opcodes::Op_AndI) {
1345     Node* bound = NULL;
1346     if (_test._test == BoolTest::le) {
1347       bound = cmp2;
1348     } else if (_test._test == BoolTest::lt &&
1349                cmp2->Opcode() == Opcodes::Op_AddI &&
1350                cmp2->in(2)->find_int_con(0) == 1) {
1351       bound = cmp2->in(1);
1352     }
1353     if (cmp1->in(2) == bound || cmp1->in(1) == bound) {
1354       return ConINode::make(1);
1355     }
1356   }
1357 
1358   // Change ((x & (m - 1)) u< m) into (m > 0)
1359   // This is the off-by-one variant of the above
1360   if (cop == Opcodes::Op_CmpU &&
1361       _test._test == BoolTest::lt &&
1362       cmp1->Opcode() == Opcodes::Op_AndI) {
1363     Node* l = cmp1->in(1);
1364     Node* r = cmp1->in(2);
1365     for (int repeat = 0; repeat < 2; repeat++) {
1366       bool match = r->Opcode() == Opcodes::Op_AddI && r->in(2)->find_int_con(0) == -1 &&
1367                    r->in(1) == cmp2;
1368       if (match) {
1369         // arraylength known to be non-negative, so a (arraylength != 0) is sufficient,
1370         // but to be compatible with the array range check pattern, use (arraylength u> 0)
1371         Node* ncmp = cmp2->Opcode() == Opcodes::Op_LoadRange
1372                      ? phase->transform(new CmpUNode(cmp2, phase->intcon(0)))
1373                      : phase->transform(new CmpINode(cmp2, phase->intcon(0)));
1374         return new BoolNode(ncmp, BoolTest::gt);
1375       } else {
1376         // commute and try again
1377         l = cmp1->in(2);
1378         r = cmp1->in(1);
1379       }
1380     }
1381   }
1382 
1383   // Change (arraylength <= 0) or (arraylength == 0)
1384   //   into (arraylength u<= 0)
1385   // Also change (arraylength != 0) into (arraylength u> 0)
1386   // The latter version matches the code pattern generated for
1387   // array range checks, which will more likely be optimized later.
1388   if (cop == Opcodes::Op_CmpI &&
1389       cmp1->Opcode() == Opcodes::Op_LoadRange &&
1390       cmp2->find_int_con(-1) == 0) {
1391     if (_test._test == BoolTest::le || _test._test == BoolTest::eq) {
1392       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1393       return new BoolNode(ncmp, BoolTest::le);
1394     } else if (_test._test == BoolTest::ne) {
1395       Node* ncmp = phase->transform(new CmpUNode(cmp1, cmp2));
1396       return new BoolNode(ncmp, BoolTest::gt);
1397     }
1398   }
1399 
1400   // Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".
1401   // This is a standard idiom for branching on a boolean value.
1402   Node *c2b = cmp1;
1403   if( cmp2_type == TypeInt::ZERO &&
1404       cmp1_op == Opcodes::Op_Conv2B &&
1405       (_test._test == BoolTest::eq ||
1406        _test._test == BoolTest::ne) ) {
1407     Node *ncmp = phase->transform(phase->type(c2b->in(1))->isa_int()
1408        ? (Node*)new CmpINode(c2b->in(1),cmp2)
1409        : (Node*)new CmpPNode(c2b->in(1),phase->makecon(TypePtr::NULL_PTR))
1410     );
1411     return new BoolNode( ncmp, _test._test );
1412   }
1413 
1414   // Comparing a SubI against a zero is equal to comparing the SubI
1415   // arguments directly.  This only works for eq and ne comparisons
1416   // due to possible integer overflow.
1417   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&
1418         (cop == Opcodes::Op_CmpI) &&
1419         (cmp1->Opcode() == Opcodes::Op_SubI) &&
1420         ( cmp2_type == TypeInt::ZERO ) ) {
1421     Node *ncmp = phase->transform( new CmpINode(cmp1->in(1),cmp1->in(2)));
1422     return new BoolNode( ncmp, _test._test );
1423   }
1424 
1425   // Change (-A vs 0) into (A vs 0) by commuting the test.  Disallow in the
1426   // most general case because negating 0x80000000 does nothing.  Needed for
1427   // the CmpF3/SubI/CmpI idiom.
1428   if( cop == Opcodes::Op_CmpI &&
1429       cmp1->Opcode() == Opcodes::Op_SubI &&
1430       cmp2_type == TypeInt::ZERO &&
1431       phase->type( cmp1->in(1) ) == TypeInt::ZERO &&
1432       phase->type( cmp1->in(2) )->higher_equal(TypeInt::SYMINT) ) {
1433     Node *ncmp = phase->transform( new CmpINode(cmp1->in(2),cmp2));
1434     return new BoolNode( ncmp, _test.commute() );
1435   }
1436 
1437   // Try to optimize signed integer comparison
1438   return fold_cmpI(phase, cmp->as_Sub(), cmp1, cop, cmp1_op, cmp2_type);
1439 
1440   //  The transformation below is not valid for either signed or unsigned
1441   //  comparisons due to wraparound concerns at MAX_VALUE and MIN_VALUE.
1442   //  This transformation can be resurrected when we are able to
1443   //  make inferences about the range of values being subtracted from
1444   //  (or added to) relative to the wraparound point.
1445   //
1446   //    // Remove +/-1's if possible.
1447   //    // "X <= Y-1" becomes "X <  Y"
1448   //    // "X+1 <= Y" becomes "X <  Y"
1449   //    // "X <  Y+1" becomes "X <= Y"


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