1 /*
   2  * Copyright (c) 1999, 2015, 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 "c1/c1_Canonicalizer.hpp"
  27 #include "c1/c1_InstructionPrinter.hpp"
  28 #include "c1/c1_ValueStack.hpp"
  29 #include "ci/ciArray.hpp"
  30 #include "runtime/sharedRuntime.hpp"
  31 
  32 
  33 class PrintValueVisitor: public ValueVisitor {
  34   void visit(Value* vp) {
  35     (*vp)->print_line();
  36   }
  37 };
  38 
  39 void Canonicalizer::set_canonical(Value x) {
  40   assert(x != NULL, "value must exist");
  41   // Note: we can not currently substitute root nodes which show up in
  42   // the instruction stream (because the instruction list is embedded
  43   // in the instructions).
  44   if (canonical() != x) {
  45 #ifndef PRODUCT
  46     if (!x->has_printable_bci()) {
  47       x->set_printable_bci(bci());
  48     }
  49 #endif
  50     if (PrintCanonicalization) {
  51       PrintValueVisitor do_print_value;
  52       canonical()->input_values_do(&do_print_value);
  53       canonical()->print_line();
  54       tty->print_cr("canonicalized to:");
  55       x->input_values_do(&do_print_value);
  56       x->print_line();
  57       tty->cr();
  58     }
  59     assert(_canonical->type()->tag() == x->type()->tag(), "types must match");
  60     _canonical = x;
  61   }
  62 }
  63 
  64 
  65 void Canonicalizer::move_const_to_right(Op2* x) {
  66   if (x->x()->type()->is_constant() && x->is_commutative()) x->swap_operands();
  67 }
  68 
  69 
  70 void Canonicalizer::do_Op2(Op2* x) {
  71   if (x->x() == x->y()) {
  72     switch (x->op()) {
  73     case Bytecodes::_isub: set_constant(0); return;
  74     case Bytecodes::_lsub: set_constant(jlong_cast(0)); return;
  75     case Bytecodes::_iand: // fall through
  76     case Bytecodes::_land: // fall through
  77     case Bytecodes::_ior:  // fall through
  78     case Bytecodes::_lor : set_canonical(x->x()); return;
  79     case Bytecodes::_ixor: set_constant(0); return;
  80     case Bytecodes::_lxor: set_constant(jlong_cast(0)); return;
  81     }
  82   }
  83 
  84   if (x->x()->type()->is_constant() && x->y()->type()->is_constant()) {
  85     // do constant folding for selected operations
  86     switch (x->type()->tag()) {
  87       case intTag:
  88         { jint a = x->x()->type()->as_IntConstant()->value();
  89           jint b = x->y()->type()->as_IntConstant()->value();
  90           switch (x->op()) {
  91             case Bytecodes::_iadd: set_constant(a + b); return;
  92             case Bytecodes::_isub: set_constant(a - b); return;
  93             case Bytecodes::_imul: set_constant(a * b); return;
  94             case Bytecodes::_idiv:
  95               if (b != 0) {
  96                 if (a == min_jint && b == -1) {
  97                   set_constant(min_jint);
  98                 } else {
  99                   set_constant(a / b);
 100                 }
 101                 return;
 102               }
 103               break;
 104             case Bytecodes::_irem:
 105               if (b != 0) {
 106                 if (a == min_jint && b == -1) {
 107                   set_constant(0);
 108                 } else {
 109                   set_constant(a % b);
 110                 }
 111                 return;
 112               }
 113               break;
 114             case Bytecodes::_iand: set_constant(a & b); return;
 115             case Bytecodes::_ior : set_constant(a | b); return;
 116             case Bytecodes::_ixor: set_constant(a ^ b); return;
 117           }
 118         }
 119         break;
 120       case longTag:
 121         { jlong a = x->x()->type()->as_LongConstant()->value();
 122           jlong b = x->y()->type()->as_LongConstant()->value();
 123           switch (x->op()) {
 124             case Bytecodes::_ladd: set_constant(a + b); return;
 125             case Bytecodes::_lsub: set_constant(a - b); return;
 126             case Bytecodes::_lmul: set_constant(a * b); return;
 127             case Bytecodes::_ldiv:
 128               if (b != 0) {
 129                 set_constant(SharedRuntime::ldiv(b, a));
 130                 return;
 131               }
 132               break;
 133             case Bytecodes::_lrem:
 134               if (b != 0) {
 135                 set_constant(SharedRuntime::lrem(b, a));
 136                 return;
 137               }
 138               break;
 139             case Bytecodes::_land: set_constant(a & b); return;
 140             case Bytecodes::_lor : set_constant(a | b); return;
 141             case Bytecodes::_lxor: set_constant(a ^ b); return;
 142           }
 143         }
 144         break;
 145       // other cases not implemented (must be extremely careful with floats & doubles!)
 146     }
 147   }
 148   // make sure constant is on the right side, if any
 149   move_const_to_right(x);
 150 
 151   if (x->y()->type()->is_constant()) {
 152     // do constant folding for selected operations
 153     switch (x->type()->tag()) {
 154       case intTag:
 155         if (x->y()->type()->as_IntConstant()->value() == 0) {
 156           switch (x->op()) {
 157             case Bytecodes::_iadd: set_canonical(x->x()); return;
 158             case Bytecodes::_isub: set_canonical(x->x()); return;
 159             case Bytecodes::_imul: set_constant(0); return;
 160               // Note: for div and rem, make sure that C semantics
 161               //       corresponds to Java semantics!
 162             case Bytecodes::_iand: set_constant(0); return;
 163             case Bytecodes::_ior : set_canonical(x->x()); return;
 164           }
 165         }
 166         break;
 167       case longTag:
 168         if (x->y()->type()->as_LongConstant()->value() == (jlong)0) {
 169           switch (x->op()) {
 170             case Bytecodes::_ladd: set_canonical(x->x()); return;
 171             case Bytecodes::_lsub: set_canonical(x->x()); return;
 172             case Bytecodes::_lmul: set_constant((jlong)0); return;
 173               // Note: for div and rem, make sure that C semantics
 174               //       corresponds to Java semantics!
 175             case Bytecodes::_land: set_constant((jlong)0); return;
 176             case Bytecodes::_lor : set_canonical(x->x()); return;
 177           }
 178         }
 179         break;
 180     }
 181   }
 182 }
 183 
 184 
 185 void Canonicalizer::do_Phi            (Phi*             x) {}
 186 void Canonicalizer::do_Constant       (Constant*        x) {}
 187 void Canonicalizer::do_Local          (Local*           x) {}
 188 void Canonicalizer::do_LoadField      (LoadField*       x) {}
 189 
 190 // checks if v is in the block that is currently processed by
 191 // GraphBuilder. This is the only block that has not BlockEnd yet.
 192 static bool in_current_block(Value v) {
 193   int max_distance = 4;
 194   while (max_distance > 0 && v != NULL && v->as_BlockEnd() == NULL) {
 195     v = v->next();
 196     max_distance--;
 197   }
 198   return v == NULL;
 199 }
 200 
 201 void Canonicalizer::do_StoreField     (StoreField*      x) {
 202   // If a value is going to be stored into a field or array some of
 203   // the conversions emitted by javac are unneeded because the fields
 204   // are packed to their natural size.
 205   Convert* conv = x->value()->as_Convert();
 206   if (conv) {
 207     Value value = NULL;
 208     BasicType type = x->field()->type()->basic_type();
 209     switch (conv->op()) {
 210     case Bytecodes::_i2b: if (type == T_BYTE)  value = conv->value(); break;
 211     case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) value = conv->value(); break;
 212     case Bytecodes::_i2c: if (type == T_CHAR  || type == T_BYTE)  value = conv->value(); break;
 213     }
 214     // limit this optimization to current block
 215     if (value != NULL && in_current_block(conv)) {
 216       set_canonical(new StoreField(x->obj(), x->offset(), x->field(), value, x->is_static(),
 217                                    x->state_before(), x->needs_patching()));
 218       return;
 219     }
 220   }
 221 
 222 }
 223 
 224 void Canonicalizer::do_ArrayLength    (ArrayLength*     x) {
 225   NewArray*  na;
 226   Constant*  ct;
 227 
 228   if ((na = x->array()->as_NewArray()) != NULL) {
 229     // New arrays might have the known length.
 230     // Do not use the Constant itself, but create a new Constant
 231     // with same value Otherwise a Constant is live over multiple
 232     // blocks without being registered in a state array.
 233     Constant* length;
 234     if (na->length() != NULL &&
 235         (length = na->length()->as_Constant()) != NULL) {
 236       assert(length->type()->as_IntConstant() != NULL, "array length must be integer");
 237       set_constant(length->type()->as_IntConstant()->value());
 238     }
 239 
 240   } else if ((ct = x->array()->as_Constant()) != NULL) {
 241     // Constant arrays have constant lengths.
 242     ArrayConstant* cnst = ct->type()->as_ArrayConstant();
 243     if (cnst != NULL) {
 244       set_constant(cnst->value()->length());
 245     }
 246 
 247 #ifdef ASSERT
 248   } else {
 249     LoadField* lf = x->array()->as_LoadField();
 250     bool is_static_constant = (lf != NULL) && lf->field()->is_constant() && lf->field()->is_static();
 251     assert(!is_static_constant, "Constant field loads are folded during parsing");
 252 #endif // ASSERT
 253   }
 254 }
 255 
 256 void Canonicalizer::do_LoadIndexed    (LoadIndexed*     x) {}
 257 void Canonicalizer::do_StoreIndexed   (StoreIndexed*    x) {
 258   // If a value is going to be stored into a field or array some of
 259   // the conversions emitted by javac are unneeded because the fields
 260   // are packed to their natural size.
 261   Convert* conv = x->value()->as_Convert();
 262   if (conv) {
 263     Value value = NULL;
 264     BasicType type = x->elt_type();
 265     switch (conv->op()) {
 266     case Bytecodes::_i2b: if (type == T_BYTE)  value = conv->value(); break;
 267     case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) value = conv->value(); break;
 268     case Bytecodes::_i2c: if (type == T_CHAR  || type == T_BYTE) value = conv->value(); break;
 269     }
 270     // limit this optimization to current block
 271     if (value != NULL && in_current_block(conv)) {
 272       set_canonical(new StoreIndexed(x->array(), x->index(), x->length(),
 273                                      x->elt_type(), value, x->state_before()));
 274       return;
 275     }
 276   }
 277 
 278 
 279 }
 280 
 281 
 282 void Canonicalizer::do_NegateOp(NegateOp* x) {
 283   ValueType* t = x->x()->type();
 284   if (t->is_constant()) {
 285     switch (t->tag()) {
 286       case intTag   : set_constant(-t->as_IntConstant   ()->value()); return;
 287       case longTag  : set_constant(-t->as_LongConstant  ()->value()); return;
 288       case floatTag : set_constant(-t->as_FloatConstant ()->value()); return;
 289       case doubleTag: set_constant(-t->as_DoubleConstant()->value()); return;
 290       default       : ShouldNotReachHere();
 291     }
 292   }
 293 }
 294 
 295 
 296 void Canonicalizer::do_ArithmeticOp   (ArithmeticOp*    x) { do_Op2(x); }
 297 
 298 
 299 void Canonicalizer::do_ShiftOp        (ShiftOp*         x) {
 300   ValueType* t = x->x()->type();
 301   ValueType* t2 = x->y()->type();
 302   if (t->is_constant()) {
 303     switch (t->tag()) {
 304     case intTag   : if (t->as_IntConstant()->value() == 0)         { set_constant(0); return; } break;
 305     case longTag  : if (t->as_LongConstant()->value() == (jlong)0) { set_constant(jlong_cast(0)); return; } break;
 306     default       : ShouldNotReachHere();
 307     }
 308     if (t2->is_constant()) {
 309       if (t->tag() == intTag) {
 310         int value = t->as_IntConstant()->value();
 311         int shift = t2->as_IntConstant()->value() & 31;
 312         jint mask = ~(~0 << (32 - shift));
 313         if (shift == 0) mask = ~0;
 314         switch (x->op()) {
 315           case Bytecodes::_ishl:  set_constant(value << shift); return;
 316           case Bytecodes::_ishr:  set_constant(value >> shift); return;
 317           case Bytecodes::_iushr: set_constant((value >> shift) & mask); return;
 318         }
 319       } else if (t->tag() == longTag) {
 320         jlong value = t->as_LongConstant()->value();
 321         int shift = t2->as_IntConstant()->value() & 63;
 322         jlong mask = ~(~jlong_cast(0) << (64 - shift));
 323         if (shift == 0) mask = ~jlong_cast(0);
 324         switch (x->op()) {
 325           case Bytecodes::_lshl:  set_constant(value << shift); return;
 326           case Bytecodes::_lshr:  set_constant(value >> shift); return;
 327           case Bytecodes::_lushr: set_constant((value >> shift) & mask); return;
 328         }
 329       }
 330     }
 331   }
 332   if (t2->is_constant()) {
 333     switch (t2->tag()) {
 334       case intTag   : if (t2->as_IntConstant()->value() == 0)  set_canonical(x->x()); return;
 335       case longTag  : if (t2->as_LongConstant()->value() == (jlong)0)  set_canonical(x->x()); return;
 336       default       : ShouldNotReachHere();
 337     }
 338   }
 339 }
 340 
 341 
 342 void Canonicalizer::do_LogicOp        (LogicOp*         x) { do_Op2(x); }
 343 void Canonicalizer::do_CompareOp      (CompareOp*       x) {
 344   if (x->x() == x->y()) {
 345     switch (x->x()->type()->tag()) {
 346       case longTag: set_constant(0); break;
 347       case floatTag: {
 348         FloatConstant* fc = x->x()->type()->as_FloatConstant();
 349         if (fc) {
 350           if (g_isnan(fc->value())) {
 351             set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
 352           } else {
 353             set_constant(0);
 354           }
 355         }
 356         break;
 357       }
 358       case doubleTag: {
 359         DoubleConstant* dc = x->x()->type()->as_DoubleConstant();
 360         if (dc) {
 361           if (g_isnan(dc->value())) {
 362             set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
 363           } else {
 364             set_constant(0);
 365           }
 366         }
 367         break;
 368       }
 369     }
 370   } else if (x->x()->type()->is_constant() && x->y()->type()->is_constant()) {
 371     switch (x->x()->type()->tag()) {
 372       case longTag: {
 373         jlong vx = x->x()->type()->as_LongConstant()->value();
 374         jlong vy = x->y()->type()->as_LongConstant()->value();
 375         if (vx == vy)
 376           set_constant(0);
 377         else if (vx < vy)
 378           set_constant(-1);
 379         else
 380           set_constant(1);
 381         break;
 382       }
 383 
 384       case floatTag: {
 385         float vx = x->x()->type()->as_FloatConstant()->value();
 386         float vy = x->y()->type()->as_FloatConstant()->value();
 387         if (g_isnan(vx) || g_isnan(vy))
 388           set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
 389         else if (vx == vy)
 390           set_constant(0);
 391         else if (vx < vy)
 392           set_constant(-1);
 393         else
 394           set_constant(1);
 395         break;
 396       }
 397 
 398       case doubleTag: {
 399         double vx = x->x()->type()->as_DoubleConstant()->value();
 400         double vy = x->y()->type()->as_DoubleConstant()->value();
 401         if (g_isnan(vx) || g_isnan(vy))
 402           set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
 403         else if (vx == vy)
 404           set_constant(0);
 405         else if (vx < vy)
 406           set_constant(-1);
 407         else
 408           set_constant(1);
 409         break;
 410       }
 411     }
 412 
 413   }
 414 }
 415 
 416 
 417 void Canonicalizer::do_IfInstanceOf(IfInstanceOf*    x) {}
 418 
 419 void Canonicalizer::do_IfOp(IfOp* x) {
 420   // Caution: do not use do_Op2(x) here for now since
 421   //          we map the condition to the op for now!
 422   move_const_to_right(x);
 423 }
 424 
 425 
 426 void Canonicalizer::do_Intrinsic      (Intrinsic*       x) {
 427   switch (x->id()) {
 428   case vmIntrinsics::_floatToRawIntBits   : {
 429     FloatConstant* c = x->argument_at(0)->type()->as_FloatConstant();
 430     if (c != NULL) {
 431       JavaValue v;
 432       v.set_jfloat(c->value());
 433       set_constant(v.get_jint());
 434     }
 435     break;
 436   }
 437   case vmIntrinsics::_intBitsToFloat      : {
 438     IntConstant* c = x->argument_at(0)->type()->as_IntConstant();
 439     if (c != NULL) {
 440       JavaValue v;
 441       v.set_jint(c->value());
 442       set_constant(v.get_jfloat());
 443     }
 444     break;
 445   }
 446   case vmIntrinsics::_doubleToRawLongBits : {
 447     DoubleConstant* c = x->argument_at(0)->type()->as_DoubleConstant();
 448     if (c != NULL) {
 449       JavaValue v;
 450       v.set_jdouble(c->value());
 451       set_constant(v.get_jlong());
 452     }
 453     break;
 454   }
 455   case vmIntrinsics::_longBitsToDouble    : {
 456     LongConstant* c = x->argument_at(0)->type()->as_LongConstant();
 457     if (c != NULL) {
 458       JavaValue v;
 459       v.set_jlong(c->value());
 460       set_constant(v.get_jdouble());
 461     }
 462     break;
 463   }
 464   case vmIntrinsics::_isInstance          : {
 465     assert(x->number_of_arguments() == 2, "wrong type");
 466 
 467     InstanceConstant* c = x->argument_at(0)->type()->as_InstanceConstant();
 468     if (c != NULL && !c->value()->is_null_object()) {
 469       // ciInstance::java_mirror_type() returns non-NULL only for Java mirrors
 470       ciType* t = c->value()->as_instance()->java_mirror_type();
 471       if (t->is_klass()) {
 472         // substitute cls.isInstance(obj) of a constant Class into
 473         // an InstantOf instruction
 474         InstanceOf* i = new InstanceOf(t->as_klass(), x->argument_at(1), x->state_before());
 475         set_canonical(i);
 476         // and try to canonicalize even further
 477         do_InstanceOf(i);
 478       } else {
 479         assert(t->is_primitive_type(), "should be a primitive type");
 480         // cls.isInstance(obj) always returns false for primitive classes
 481         set_constant(0);
 482       }
 483     }
 484     break;
 485   }
 486   }
 487 }
 488 
 489 void Canonicalizer::do_Convert        (Convert*         x) {
 490   if (x->value()->type()->is_constant()) {
 491     switch (x->op()) {
 492     case Bytecodes::_i2b:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 24) >> 24)); break;
 493     case Bytecodes::_i2s:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 16) >> 16)); break;
 494     case Bytecodes::_i2c:  set_constant((int)(x->value()->type()->as_IntConstant()->value() & ((1<<16)-1))); break;
 495     case Bytecodes::_i2l:  set_constant((jlong)(x->value()->type()->as_IntConstant()->value()));             break;
 496     case Bytecodes::_i2f:  set_constant((float)(x->value()->type()->as_IntConstant()->value()));             break;
 497     case Bytecodes::_i2d:  set_constant((double)(x->value()->type()->as_IntConstant()->value()));            break;
 498     case Bytecodes::_l2i:  set_constant((int)(x->value()->type()->as_LongConstant()->value()));              break;
 499     case Bytecodes::_l2f:  set_constant(SharedRuntime::l2f(x->value()->type()->as_LongConstant()->value())); break;
 500     case Bytecodes::_l2d:  set_constant(SharedRuntime::l2d(x->value()->type()->as_LongConstant()->value())); break;
 501     case Bytecodes::_f2d:  set_constant((double)(x->value()->type()->as_FloatConstant()->value()));          break;
 502     case Bytecodes::_f2i:  set_constant(SharedRuntime::f2i(x->value()->type()->as_FloatConstant()->value())); break;
 503     case Bytecodes::_f2l:  set_constant(SharedRuntime::f2l(x->value()->type()->as_FloatConstant()->value())); break;
 504     case Bytecodes::_d2f:  set_constant((float)(x->value()->type()->as_DoubleConstant()->value()));          break;
 505     case Bytecodes::_d2i:  set_constant(SharedRuntime::d2i(x->value()->type()->as_DoubleConstant()->value())); break;
 506     case Bytecodes::_d2l:  set_constant(SharedRuntime::d2l(x->value()->type()->as_DoubleConstant()->value())); break;
 507     default:
 508       ShouldNotReachHere();
 509     }
 510   }
 511 
 512   Value value = x->value();
 513   BasicType type = T_ILLEGAL;
 514   LoadField* lf = value->as_LoadField();
 515   if (lf) {
 516     type = lf->field_type();
 517   } else {
 518     LoadIndexed* li = value->as_LoadIndexed();
 519     if (li) {
 520       type = li->elt_type();
 521     } else {
 522       Convert* conv = value->as_Convert();
 523       if (conv) {
 524         switch (conv->op()) {
 525           case Bytecodes::_i2b: type = T_BYTE;  break;
 526           case Bytecodes::_i2s: type = T_SHORT; break;
 527           case Bytecodes::_i2c: type = T_CHAR;  break;
 528         }
 529       }
 530     }
 531   }
 532   if (type != T_ILLEGAL) {
 533     switch (x->op()) {
 534       case Bytecodes::_i2b: if (type == T_BYTE)                    set_canonical(x->value()); break;
 535       case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) set_canonical(x->value()); break;
 536       case Bytecodes::_i2c: if (type == T_CHAR)                    set_canonical(x->value()); break;
 537     }
 538   } else {
 539     Op2* op2 = x->value()->as_Op2();
 540     if (op2 && op2->op() == Bytecodes::_iand && op2->y()->type()->is_constant()) {
 541       jint safebits = 0;
 542       jint mask = op2->y()->type()->as_IntConstant()->value();
 543       switch (x->op()) {
 544         case Bytecodes::_i2b: safebits = 0x7f;   break;
 545         case Bytecodes::_i2s: safebits = 0x7fff; break;
 546         case Bytecodes::_i2c: safebits = 0xffff; break;
 547       }
 548       // When casting a masked integer to a smaller signed type, if
 549       // the mask doesn't include the sign bit the cast isn't needed.
 550       if (safebits && (mask & ~safebits) == 0) {
 551         set_canonical(x->value());
 552       }
 553     }
 554   }
 555 
 556 }
 557 
 558 void Canonicalizer::do_NullCheck      (NullCheck*       x) {
 559   if (x->obj()->as_NewArray() != NULL || x->obj()->as_NewInstance() != NULL) {
 560     set_canonical(x->obj());
 561   } else {
 562     Constant* con = x->obj()->as_Constant();
 563     if (con) {
 564       ObjectType* c = con->type()->as_ObjectType();
 565       if (c && c->is_loaded()) {
 566         ObjectConstant* oc = c->as_ObjectConstant();
 567         if (!oc || !oc->value()->is_null_object()) {
 568           set_canonical(con);
 569         }
 570       }
 571     }
 572   }
 573 }
 574 
 575 void Canonicalizer::do_TypeCast       (TypeCast*        x) {}
 576 void Canonicalizer::do_Invoke         (Invoke*          x) {}
 577 void Canonicalizer::do_NewInstance    (NewInstance*     x) {}
 578 void Canonicalizer::do_NewTypeArray   (NewTypeArray*    x) {}
 579 void Canonicalizer::do_NewObjectArray (NewObjectArray*  x) {}
 580 void Canonicalizer::do_NewMultiArray  (NewMultiArray*   x) {}
 581 void Canonicalizer::do_CheckCast      (CheckCast*       x) {
 582   if (x->klass()->is_loaded()) {
 583     Value obj = x->obj();
 584     ciType* klass = obj->exact_type();
 585     if (klass == NULL) klass = obj->declared_type();
 586     if (klass != NULL && klass->is_loaded() && klass->is_subtype_of(x->klass())) {
 587       set_canonical(obj);
 588       return;
 589     }
 590     // checkcast of null returns null
 591     if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
 592       set_canonical(obj);
 593     }
 594   }
 595 }
 596 void Canonicalizer::do_InstanceOf     (InstanceOf*      x) {
 597   if (x->klass()->is_loaded()) {
 598     Value obj = x->obj();
 599     ciType* exact = obj->exact_type();
 600     if (exact != NULL && exact->is_loaded() && (obj->as_NewInstance() || obj->as_NewArray())) {
 601       set_constant(exact->is_subtype_of(x->klass()) ? 1 : 0);
 602       return;
 603     }
 604     // instanceof null returns false
 605     if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
 606       set_constant(0);
 607     }
 608   }
 609 
 610 }
 611 void Canonicalizer::do_MonitorEnter   (MonitorEnter*    x) {}
 612 void Canonicalizer::do_MonitorExit    (MonitorExit*     x) {}
 613 void Canonicalizer::do_BlockBegin     (BlockBegin*      x) {}
 614 void Canonicalizer::do_Goto           (Goto*            x) {}
 615 
 616 
 617 static bool is_true(jlong x, If::Condition cond, jlong y) {
 618   switch (cond) {
 619     case If::eql: return x == y;
 620     case If::neq: return x != y;
 621     case If::lss: return x <  y;
 622     case If::leq: return x <= y;
 623     case If::gtr: return x >  y;
 624     case If::geq: return x >= y;
 625   }
 626   ShouldNotReachHere();
 627   return false;
 628 }
 629 
 630 static bool is_safepoint(BlockEnd* x, BlockBegin* sux) {
 631   // An Instruction with multiple successors, x, is replaced by a Goto
 632   // to a single successor, sux. Is a safepoint check needed = was the
 633   // instruction being replaced a safepoint and the single remaining
 634   // successor a back branch?
 635   return x->is_safepoint() && (sux->bci() < x->state_before()->bci());
 636 }
 637 
 638 void Canonicalizer::do_If(If* x) {
 639   // move const to right
 640   if (x->x()->type()->is_constant()) x->swap_operands();
 641   // simplify
 642   const Value l = x->x(); ValueType* lt = l->type();
 643   const Value r = x->y(); ValueType* rt = r->type();
 644 
 645   if (l == r && !lt->is_float_kind()) {
 646     // pattern: If (a cond a) => simplify to Goto
 647     BlockBegin* sux = NULL;
 648     switch (x->cond()) {
 649     case If::eql: sux = x->sux_for(true);  break;
 650     case If::neq: sux = x->sux_for(false); break;
 651     case If::lss: sux = x->sux_for(false); break;
 652     case If::leq: sux = x->sux_for(true);  break;
 653     case If::gtr: sux = x->sux_for(false); break;
 654     case If::geq: sux = x->sux_for(true);  break;
 655     default: ShouldNotReachHere();
 656     }
 657     // If is a safepoint then the debug information should come from the state_before of the If.
 658     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 659     return;
 660   }
 661 
 662   if (lt->is_constant() && rt->is_constant()) {
 663     if (x->x()->as_Constant() != NULL) {
 664       // pattern: If (lc cond rc) => simplify to: Goto
 665       BlockBegin* sux = x->x()->as_Constant()->compare(x->cond(), x->y(),
 666                                                        x->sux_for(true),
 667                                                        x->sux_for(false));
 668       if (sux != NULL) {
 669         // If is a safepoint then the debug information should come from the state_before of the If.
 670         set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 671       }
 672     }
 673   } else if (rt->as_IntConstant() != NULL) {
 674     // pattern: If (l cond rc) => investigate further
 675     const jint rc = rt->as_IntConstant()->value();
 676     if (l->as_CompareOp() != NULL) {
 677       // pattern: If ((a cmp b) cond rc) => simplify to: If (x cond y) or: Goto
 678       CompareOp* cmp = l->as_CompareOp();
 679       bool unordered_is_less = cmp->op() == Bytecodes::_fcmpl || cmp->op() == Bytecodes::_dcmpl;
 680       BlockBegin* lss_sux = x->sux_for(is_true(-1, x->cond(), rc)); // successor for a < b
 681       BlockBegin* eql_sux = x->sux_for(is_true( 0, x->cond(), rc)); // successor for a = b
 682       BlockBegin* gtr_sux = x->sux_for(is_true(+1, x->cond(), rc)); // successor for a > b
 683       BlockBegin* nan_sux = unordered_is_less ? lss_sux : gtr_sux ; // successor for unordered
 684       // Note: At this point all successors (lss_sux, eql_sux, gtr_sux, nan_sux) are
 685       //       equal to x->tsux() or x->fsux(). Furthermore, nan_sux equals either
 686       //       lss_sux or gtr_sux.
 687       if (lss_sux == eql_sux && eql_sux == gtr_sux) {
 688         // all successors identical => simplify to: Goto
 689         set_canonical(new Goto(lss_sux, x->state_before(), x->is_safepoint()));
 690       } else {
 691         // two successors differ and two successors are the same => simplify to: If (x cmp y)
 692         // determine new condition & successors
 693         If::Condition cond = If::eql;
 694         BlockBegin* tsux = NULL;
 695         BlockBegin* fsux = NULL;
 696              if (lss_sux == eql_sux) { cond = If::leq; tsux = lss_sux; fsux = gtr_sux; }
 697         else if (lss_sux == gtr_sux) { cond = If::neq; tsux = lss_sux; fsux = eql_sux; }
 698         else if (eql_sux == gtr_sux) { cond = If::geq; tsux = eql_sux; fsux = lss_sux; }
 699         else                         { ShouldNotReachHere();                           }
 700         If* canon = new If(cmp->x(), cond, nan_sux == tsux, cmp->y(), tsux, fsux, cmp->state_before(), x->is_safepoint());
 701         if (cmp->x() == cmp->y()) {
 702           do_If(canon);
 703         } else {
 704           if (compilation()->profile_branches()) {
 705             // TODO: If profiling, leave floating point comparisons unoptimized.
 706             // We currently do not support profiling of the unordered case.
 707             switch(cmp->op()) {
 708               case Bytecodes::_fcmpl: case Bytecodes::_fcmpg:
 709               case Bytecodes::_dcmpl: case Bytecodes::_dcmpg:
 710                 set_canonical(x);
 711                 return;
 712             }
 713           }
 714           set_bci(cmp->state_before()->bci());
 715           set_canonical(canon);
 716         }
 717       }
 718     } else if (l->as_InstanceOf() != NULL) {
 719       // NOTE: Code permanently disabled for now since it leaves the old InstanceOf
 720       //       instruction in the graph (it is pinned). Need to fix this at some point.
 721       //       It should also be left in the graph when generating a profiled method version or Goto
 722       //       has to know that it was an InstanceOf.
 723       return;
 724       // pattern: If ((obj instanceof klass) cond rc) => simplify to: IfInstanceOf or: Goto
 725       InstanceOf* inst = l->as_InstanceOf();
 726       BlockBegin* is_inst_sux = x->sux_for(is_true(1, x->cond(), rc)); // successor for instanceof == 1
 727       BlockBegin* no_inst_sux = x->sux_for(is_true(0, x->cond(), rc)); // successor for instanceof == 0
 728       if (is_inst_sux == no_inst_sux && inst->is_loaded()) {
 729         // both successors identical and klass is loaded => simplify to: Goto
 730         set_canonical(new Goto(is_inst_sux, x->state_before(), x->is_safepoint()));
 731       } else {
 732         // successors differ => simplify to: IfInstanceOf
 733         set_canonical(new IfInstanceOf(inst->klass(), inst->obj(), true, inst->state_before()->bci(), is_inst_sux, no_inst_sux));
 734       }
 735     }
 736   } else if (rt == objectNull &&
 737            (l->as_NewInstance() || l->as_NewArray() ||
 738              (l->as_Local() && l->as_Local()->is_receiver()))) {
 739     if (x->cond() == Instruction::eql) {
 740       BlockBegin* sux = x->fsux();
 741       set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 742     } else {
 743       assert(x->cond() == Instruction::neq, "only other valid case");
 744       BlockBegin* sux = x->tsux();
 745       set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 746     }
 747   }
 748 }
 749 
 750 
 751 void Canonicalizer::do_TableSwitch(TableSwitch* x) {
 752   if (x->tag()->type()->is_constant()) {
 753     int v = x->tag()->type()->as_IntConstant()->value();
 754     BlockBegin* sux = x->default_sux();
 755     if (v >= x->lo_key() && v <= x->hi_key()) {
 756       sux = x->sux_at(v - x->lo_key());
 757     }
 758     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 759   } else if (x->number_of_sux() == 1) {
 760     // NOTE: Code permanently disabled for now since the switch statement's
 761     //       tag expression may produce side-effects in which case it must
 762     //       be executed.
 763     return;
 764     // simplify to Goto
 765     set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
 766   } else if (x->number_of_sux() == 2) {
 767     // NOTE: Code permanently disabled for now since it produces two new nodes
 768     //       (Constant & If) and the Canonicalizer cannot return them correctly
 769     //       yet. For now we copied the corresponding code directly into the
 770     //       GraphBuilder (i.e., we should never reach here).
 771     return;
 772     // simplify to If
 773     assert(x->lo_key() == x->hi_key(), "keys must be the same");
 774     Constant* key = new Constant(new IntConstant(x->lo_key()));
 775     set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
 776   }
 777 }
 778 
 779 
 780 void Canonicalizer::do_LookupSwitch(LookupSwitch* x) {
 781   if (x->tag()->type()->is_constant()) {
 782     int v = x->tag()->type()->as_IntConstant()->value();
 783     BlockBegin* sux = x->default_sux();
 784     for (int i = 0; i < x->length(); i++) {
 785       if (v == x->key_at(i)) {
 786         sux = x->sux_at(i);
 787       }
 788     }
 789     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 790   } else if (x->number_of_sux() == 1) {
 791     // NOTE: Code permanently disabled for now since the switch statement's
 792     //       tag expression may produce side-effects in which case it must
 793     //       be executed.
 794     return;
 795     // simplify to Goto
 796     set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
 797   } else if (x->number_of_sux() == 2) {
 798     // NOTE: Code permanently disabled for now since it produces two new nodes
 799     //       (Constant & If) and the Canonicalizer cannot return them correctly
 800     //       yet. For now we copied the corresponding code directly into the
 801     //       GraphBuilder (i.e., we should never reach here).
 802     return;
 803     // simplify to If
 804     assert(x->length() == 1, "length must be the same");
 805     Constant* key = new Constant(new IntConstant(x->key_at(0)));
 806     set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
 807   }
 808 }
 809 
 810 
 811 void Canonicalizer::do_Return         (Return*          x) {}
 812 void Canonicalizer::do_Throw          (Throw*           x) {}
 813 void Canonicalizer::do_Base           (Base*            x) {}
 814 void Canonicalizer::do_OsrEntry       (OsrEntry*        x) {}
 815 void Canonicalizer::do_ExceptionObject(ExceptionObject* x) {}
 816 
 817 static bool match_index_and_scale(Instruction*  instr,
 818                                   Instruction** index,
 819                                   int*          log2_scale) {
 820   // Skip conversion ops. This works only on 32bit because of the implicit l2i that the
 821   // unsafe performs.
 822 #ifndef _LP64
 823   Convert* convert = instr->as_Convert();
 824   if (convert != NULL && convert->op() == Bytecodes::_i2l) {
 825     assert(convert->value()->type() == intType, "invalid input type");
 826     instr = convert->value();
 827   }
 828 #endif
 829 
 830   ShiftOp* shift = instr->as_ShiftOp();
 831   if (shift != NULL) {
 832     if (shift->op() == Bytecodes::_lshl) {
 833       assert(shift->x()->type() == longType, "invalid input type");
 834     } else {
 835 #ifndef _LP64
 836       if (shift->op() == Bytecodes::_ishl) {
 837         assert(shift->x()->type() == intType, "invalid input type");
 838       } else {
 839         return false;
 840       }
 841 #else
 842       return false;
 843 #endif
 844     }
 845 
 846 
 847     // Constant shift value?
 848     Constant* con = shift->y()->as_Constant();
 849     if (con == NULL) return false;
 850     // Well-known type and value?
 851     IntConstant* val = con->type()->as_IntConstant();
 852     assert(val != NULL, "Should be an int constant");
 853 
 854     *index = shift->x();
 855     int tmp_scale = val->value();
 856     if (tmp_scale >= 0 && tmp_scale < 4) {
 857       *log2_scale = tmp_scale;
 858       return true;
 859     } else {
 860       return false;
 861     }
 862   }
 863 
 864   ArithmeticOp* arith = instr->as_ArithmeticOp();
 865   if (arith != NULL) {
 866     // See if either arg is a known constant
 867     Constant* con = arith->x()->as_Constant();
 868     if (con != NULL) {
 869       *index = arith->y();
 870     } else {
 871       con = arith->y()->as_Constant();
 872       if (con == NULL) return false;
 873       *index = arith->x();
 874     }
 875     long const_value;
 876     // Check for integer multiply
 877     if (arith->op() == Bytecodes::_lmul) {
 878       assert((*index)->type() == longType, "invalid input type");
 879       LongConstant* val = con->type()->as_LongConstant();
 880       assert(val != NULL, "expecting a long constant");
 881       const_value = val->value();
 882     } else {
 883 #ifndef _LP64
 884       if (arith->op() == Bytecodes::_imul) {
 885         assert((*index)->type() == intType, "invalid input type");
 886         IntConstant* val = con->type()->as_IntConstant();
 887         assert(val != NULL, "expecting an int constant");
 888         const_value = val->value();
 889       } else {
 890         return false;
 891       }
 892 #else
 893       return false;
 894 #endif
 895     }
 896     switch (const_value) {
 897     case 1: *log2_scale = 0; return true;
 898     case 2: *log2_scale = 1; return true;
 899     case 4: *log2_scale = 2; return true;
 900     case 8: *log2_scale = 3; return true;
 901     default:            return false;
 902     }
 903   }
 904 
 905   // Unknown instruction sequence; don't touch it
 906   return false;
 907 }
 908 
 909 
 910 static bool match(UnsafeRawOp* x,
 911                   Instruction** base,
 912                   Instruction** index,
 913                   int*          log2_scale) {
 914   ArithmeticOp* root = x->base()->as_ArithmeticOp();
 915   if (root == NULL) return false;
 916   // Limit ourselves to addition for now
 917   if (root->op() != Bytecodes::_ladd) return false;
 918 
 919   bool match_found = false;
 920   // Try to find shift or scale op
 921   if (match_index_and_scale(root->y(), index, log2_scale)) {
 922     *base = root->x();
 923     match_found = true;
 924   } else if (match_index_and_scale(root->x(), index, log2_scale)) {
 925     *base = root->y();
 926     match_found = true;
 927   } else if (NOT_LP64(root->y()->as_Convert() != NULL) LP64_ONLY(false)) {
 928     // Skipping i2l works only on 32bit because of the implicit l2i that the unsafe performs.
 929     // 64bit needs a real sign-extending conversion.
 930     Convert* convert = root->y()->as_Convert();
 931     if (convert->op() == Bytecodes::_i2l) {
 932       assert(convert->value()->type() == intType, "should be an int");
 933       // pick base and index, setting scale at 1
 934       *base  = root->x();
 935       *index = convert->value();
 936       *log2_scale = 0;
 937       match_found = true;
 938     }
 939   }
 940   // The default solution
 941   if (!match_found) {
 942     *base = root->x();
 943     *index = root->y();
 944     *log2_scale = 0;
 945   }
 946 
 947   // If the value is pinned then it will be always be computed so
 948   // there's no profit to reshaping the expression.
 949   return !root->is_pinned();
 950 }
 951 
 952 
 953 void Canonicalizer::do_UnsafeRawOp(UnsafeRawOp* x) {
 954   Instruction* base = NULL;
 955   Instruction* index = NULL;
 956   int          log2_scale;
 957 
 958   if (match(x, &base, &index, &log2_scale)) {
 959     x->set_base(base);
 960     x->set_index(index);
 961     x->set_log2_scale(log2_scale);
 962     if (PrintUnsafeOptimization) {
 963       tty->print_cr("Canonicalizer: UnsafeRawOp id %d: base = id %d, index = id %d, log2_scale = %d",
 964                     x->id(), x->base()->id(), x->index()->id(), x->log2_scale());
 965     }
 966   }
 967 }
 968 
 969 void Canonicalizer::do_RoundFP(RoundFP* x) {}
 970 void Canonicalizer::do_UnsafeGetRaw(UnsafeGetRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
 971 void Canonicalizer::do_UnsafePutRaw(UnsafePutRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
 972 void Canonicalizer::do_UnsafeGetObject(UnsafeGetObject* x) {}
 973 void Canonicalizer::do_UnsafePutObject(UnsafePutObject* x) {}
 974 void Canonicalizer::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {}
 975 void Canonicalizer::do_ProfileCall(ProfileCall* x) {}
 976 void Canonicalizer::do_ProfileReturnType(ProfileReturnType* x) {}
 977 void Canonicalizer::do_ProfileInvoke(ProfileInvoke* x) {}
 978 void Canonicalizer::do_RuntimeCall(RuntimeCall* x) {}
 979 void Canonicalizer::do_RangeCheckPredicate(RangeCheckPredicate* x) {}
 980 #ifdef ASSERT
 981 void Canonicalizer::do_Assert(Assert* x) {}
 982 #endif
 983 void Canonicalizer::do_MemBar(MemBar* x) {}