1 /*
   2  * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "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* array = x->array()->as_NewArray();
 226   if (array != NULL && array->length() != NULL) {
 227     Constant* length = array->length()->as_Constant();
 228     if (length != NULL) {
 229       // do not use the Constant itself, but create a new Constant
 230       // with same value Otherwise a Constant is live over multiple
 231       // blocks without being registered in a state array.
 232       assert(length->type()->as_IntConstant() != NULL, "array length must be integer");
 233       set_constant(length->type()->as_IntConstant()->value());
 234     }
 235   } else {
 236     LoadField* lf = x->array()->as_LoadField();
 237     if (lf != NULL) {
 238       ciField* field = lf->field();
 239       if (field->is_constant() && field->is_static()) {
 240         // final static field
 241         ciObject* c = field->constant_value().as_object();
 242         if (c->is_array()) {
 243           ciArray* array = (ciArray*) c;
 244           set_constant(array->length());
 245         }
 246       }
 247     }
 248   }
 249 }
 250 
 251 void Canonicalizer::do_LoadIndexed    (LoadIndexed*     x) {}
 252 void Canonicalizer::do_StoreIndexed   (StoreIndexed*    x) {
 253   // If a value is going to be stored into a field or array some of
 254   // the conversions emitted by javac are unneeded because the fields
 255   // are packed to their natural size.
 256   Convert* conv = x->value()->as_Convert();
 257   if (conv) {
 258     Value value = NULL;
 259     BasicType type = x->elt_type();
 260     switch (conv->op()) {
 261     case Bytecodes::_i2b: if (type == T_BYTE)  value = conv->value(); break;
 262     case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) value = conv->value(); break;
 263     case Bytecodes::_i2c: if (type == T_CHAR  || type == T_BYTE) value = conv->value(); break;
 264     }
 265     // limit this optimization to current block
 266     if (value != NULL && in_current_block(conv)) {
 267       set_canonical(new StoreIndexed(x->array(), x->index(), x->length(),
 268                                      x->elt_type(), value, x->state_before()));
 269       return;
 270     }
 271   }
 272 
 273 
 274 }
 275 
 276 
 277 void Canonicalizer::do_NegateOp(NegateOp* x) {
 278   ValueType* t = x->x()->type();
 279   if (t->is_constant()) {
 280     switch (t->tag()) {
 281       case intTag   : set_constant(-t->as_IntConstant   ()->value()); return;
 282       case longTag  : set_constant(-t->as_LongConstant  ()->value()); return;
 283       case floatTag : set_constant(-t->as_FloatConstant ()->value()); return;
 284       case doubleTag: set_constant(-t->as_DoubleConstant()->value()); return;
 285       default       : ShouldNotReachHere();
 286     }
 287   }
 288 }
 289 
 290 
 291 void Canonicalizer::do_ArithmeticOp   (ArithmeticOp*    x) { do_Op2(x); }
 292 
 293 
 294 void Canonicalizer::do_ShiftOp        (ShiftOp*         x) {
 295   ValueType* t = x->x()->type();
 296   ValueType* t2 = x->y()->type();
 297   if (t->is_constant()) {
 298     switch (t->tag()) {
 299     case intTag   : if (t->as_IntConstant()->value() == 0)         { set_constant(0); return; } break;
 300     case longTag  : if (t->as_LongConstant()->value() == (jlong)0) { set_constant(jlong_cast(0)); return; } break;
 301     default       : ShouldNotReachHere();
 302     }
 303     if (t2->is_constant()) {
 304       if (t->tag() == intTag) {
 305         int value = t->as_IntConstant()->value();
 306         int shift = t2->as_IntConstant()->value() & 31;
 307         jint mask = ~(~0 << (32 - shift));
 308         if (shift == 0) mask = ~0;
 309         switch (x->op()) {
 310           case Bytecodes::_ishl:  set_constant(value << shift); return;
 311           case Bytecodes::_ishr:  set_constant(value >> shift); return;
 312           case Bytecodes::_iushr: set_constant((value >> shift) & mask); return;
 313         }
 314       } else if (t->tag() == longTag) {
 315         jlong value = t->as_LongConstant()->value();
 316         int shift = t2->as_IntConstant()->value() & 63;
 317         jlong mask = ~(~jlong_cast(0) << (64 - shift));
 318         if (shift == 0) mask = ~jlong_cast(0);
 319         switch (x->op()) {
 320           case Bytecodes::_lshl:  set_constant(value << shift); return;
 321           case Bytecodes::_lshr:  set_constant(value >> shift); return;
 322           case Bytecodes::_lushr: set_constant((value >> shift) & mask); return;
 323         }
 324       }
 325     }
 326   }
 327   if (t2->is_constant()) {
 328     switch (t2->tag()) {
 329       case intTag   : if (t2->as_IntConstant()->value() == 0)  set_canonical(x->x()); return;
 330       case longTag  : if (t2->as_IntConstant()->value() == 0)  set_canonical(x->x()); return;
 331       default       : ShouldNotReachHere();
 332     }
 333   }
 334 }
 335 
 336 
 337 void Canonicalizer::do_LogicOp        (LogicOp*         x) { do_Op2(x); }
 338 void Canonicalizer::do_CompareOp      (CompareOp*       x) {
 339   if (x->x() == x->y()) {
 340     switch (x->x()->type()->tag()) {
 341       case longTag: set_constant(0); break;
 342       case floatTag: {
 343         FloatConstant* fc = x->x()->type()->as_FloatConstant();
 344         if (fc) {
 345           if (g_isnan(fc->value())) {
 346             set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
 347           } else {
 348             set_constant(0);
 349           }
 350         }
 351         break;
 352       }
 353       case doubleTag: {
 354         DoubleConstant* dc = x->x()->type()->as_DoubleConstant();
 355         if (dc) {
 356           if (g_isnan(dc->value())) {
 357             set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
 358           } else {
 359             set_constant(0);
 360           }
 361         }
 362         break;
 363       }
 364     }
 365   } else if (x->x()->type()->is_constant() && x->y()->type()->is_constant()) {
 366     switch (x->x()->type()->tag()) {
 367       case longTag: {
 368         jlong vx = x->x()->type()->as_LongConstant()->value();
 369         jlong vy = x->y()->type()->as_LongConstant()->value();
 370         if (vx == vy)
 371           set_constant(0);
 372         else if (vx < vy)
 373           set_constant(-1);
 374         else
 375           set_constant(1);
 376         break;
 377       }
 378 
 379       case floatTag: {
 380         float vx = x->x()->type()->as_FloatConstant()->value();
 381         float vy = x->y()->type()->as_FloatConstant()->value();
 382         if (g_isnan(vx) || g_isnan(vy))
 383           set_constant(x->op() == Bytecodes::_fcmpl ? -1 : 1);
 384         else if (vx == vy)
 385           set_constant(0);
 386         else if (vx < vy)
 387           set_constant(-1);
 388         else
 389           set_constant(1);
 390         break;
 391       }
 392 
 393       case doubleTag: {
 394         double vx = x->x()->type()->as_DoubleConstant()->value();
 395         double vy = x->y()->type()->as_DoubleConstant()->value();
 396         if (g_isnan(vx) || g_isnan(vy))
 397           set_constant(x->op() == Bytecodes::_dcmpl ? -1 : 1);
 398         else if (vx == vy)
 399           set_constant(0);
 400         else if (vx < vy)
 401           set_constant(-1);
 402         else
 403           set_constant(1);
 404         break;
 405       }
 406     }
 407 
 408   }
 409 }
 410 
 411 
 412 void Canonicalizer::do_IfInstanceOf(IfInstanceOf*    x) {}
 413 
 414 void Canonicalizer::do_IfOp(IfOp* x) {
 415   // Caution: do not use do_Op2(x) here for now since
 416   //          we map the condition to the op for now!
 417   move_const_to_right(x);
 418 }
 419 
 420 
 421 void Canonicalizer::do_Intrinsic      (Intrinsic*       x) {
 422   switch (x->id()) {
 423   case vmIntrinsics::_floatToRawIntBits   : {
 424     FloatConstant* c = x->argument_at(0)->type()->as_FloatConstant();
 425     if (c != NULL) {
 426       JavaValue v;
 427       v.set_jfloat(c->value());
 428       set_constant(v.get_jint());
 429     }
 430     break;
 431   }
 432   case vmIntrinsics::_intBitsToFloat      : {
 433     IntConstant* c = x->argument_at(0)->type()->as_IntConstant();
 434     if (c != NULL) {
 435       JavaValue v;
 436       v.set_jint(c->value());
 437       set_constant(v.get_jfloat());
 438     }
 439     break;
 440   }
 441   case vmIntrinsics::_doubleToRawLongBits : {
 442     DoubleConstant* c = x->argument_at(0)->type()->as_DoubleConstant();
 443     if (c != NULL) {
 444       JavaValue v;
 445       v.set_jdouble(c->value());
 446       set_constant(v.get_jlong());
 447     }
 448     break;
 449   }
 450   case vmIntrinsics::_longBitsToDouble    : {
 451     LongConstant* c = x->argument_at(0)->type()->as_LongConstant();
 452     if (c != NULL) {
 453       JavaValue v;
 454       v.set_jlong(c->value());
 455       set_constant(v.get_jdouble());
 456     }
 457     break;
 458   }
 459   case vmIntrinsics::_isInstance          : {
 460     assert(x->number_of_arguments() == 2, "wrong type");
 461 
 462     InstanceConstant* c = x->argument_at(0)->type()->as_InstanceConstant();
 463     if (c != NULL && !c->value()->is_null_object()) {
 464       // ciInstance::java_mirror_type() returns non-NULL only for Java mirrors
 465       ciType* t = c->value()->as_instance()->java_mirror_type();
 466       if (t->is_klass()) {
 467         // substitute cls.isInstance(obj) of a constant Class into
 468         // an InstantOf instruction
 469         InstanceOf* i = new InstanceOf(t->as_klass(), x->argument_at(1), x->state_before());
 470         set_canonical(i);
 471         // and try to canonicalize even further
 472         do_InstanceOf(i);
 473       } else {
 474         assert(t->is_primitive_type(), "should be a primitive type");
 475         // cls.isInstance(obj) always returns false for primitive classes
 476         set_constant(0);
 477       }
 478     }
 479     break;
 480   }
 481   }
 482 }
 483 
 484 void Canonicalizer::do_Convert        (Convert*         x) {
 485   if (x->value()->type()->is_constant()) {
 486     switch (x->op()) {
 487     case Bytecodes::_i2b:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 24) >> 24)); break;
 488     case Bytecodes::_i2s:  set_constant((int)((x->value()->type()->as_IntConstant()->value() << 16) >> 16)); break;
 489     case Bytecodes::_i2c:  set_constant((int)(x->value()->type()->as_IntConstant()->value() & ((1<<16)-1))); break;
 490     case Bytecodes::_i2l:  set_constant((jlong)(x->value()->type()->as_IntConstant()->value()));             break;
 491     case Bytecodes::_i2f:  set_constant((float)(x->value()->type()->as_IntConstant()->value()));             break;
 492     case Bytecodes::_i2d:  set_constant((double)(x->value()->type()->as_IntConstant()->value()));            break;
 493     case Bytecodes::_l2i:  set_constant((int)(x->value()->type()->as_LongConstant()->value()));              break;
 494     case Bytecodes::_l2f:  set_constant(SharedRuntime::l2f(x->value()->type()->as_LongConstant()->value())); break;
 495     case Bytecodes::_l2d:  set_constant(SharedRuntime::l2d(x->value()->type()->as_LongConstant()->value())); break;
 496     case Bytecodes::_f2d:  set_constant((double)(x->value()->type()->as_FloatConstant()->value()));          break;
 497     case Bytecodes::_f2i:  set_constant(SharedRuntime::f2i(x->value()->type()->as_FloatConstant()->value())); break;
 498     case Bytecodes::_f2l:  set_constant(SharedRuntime::f2l(x->value()->type()->as_FloatConstant()->value())); break;
 499     case Bytecodes::_d2f:  set_constant((float)(x->value()->type()->as_DoubleConstant()->value()));          break;
 500     case Bytecodes::_d2i:  set_constant(SharedRuntime::d2i(x->value()->type()->as_DoubleConstant()->value())); break;
 501     case Bytecodes::_d2l:  set_constant(SharedRuntime::d2l(x->value()->type()->as_DoubleConstant()->value())); break;
 502     default:
 503       ShouldNotReachHere();
 504     }
 505   }
 506 
 507   Value value = x->value();
 508   BasicType type = T_ILLEGAL;
 509   LoadField* lf = value->as_LoadField();
 510   if (lf) {
 511     type = lf->field_type();
 512   } else {
 513     LoadIndexed* li = value->as_LoadIndexed();
 514     if (li) {
 515       type = li->elt_type();
 516     } else {
 517       Convert* conv = value->as_Convert();
 518       if (conv) {
 519         switch (conv->op()) {
 520           case Bytecodes::_i2b: type = T_BYTE;  break;
 521           case Bytecodes::_i2s: type = T_SHORT; break;
 522           case Bytecodes::_i2c: type = T_CHAR;  break;
 523         }
 524       }
 525     }
 526   }
 527   if (type != T_ILLEGAL) {
 528     switch (x->op()) {
 529       case Bytecodes::_i2b: if (type == T_BYTE)                    set_canonical(x->value()); break;
 530       case Bytecodes::_i2s: if (type == T_SHORT || type == T_BYTE) set_canonical(x->value()); break;
 531       case Bytecodes::_i2c: if (type == T_CHAR)                    set_canonical(x->value()); break;
 532     }
 533   } else {
 534     Op2* op2 = x->value()->as_Op2();
 535     if (op2 && op2->op() == Bytecodes::_iand && op2->y()->type()->is_constant()) {
 536       jint safebits = 0;
 537       jint mask = op2->y()->type()->as_IntConstant()->value();
 538       switch (x->op()) {
 539         case Bytecodes::_i2b: safebits = 0x7f;   break;
 540         case Bytecodes::_i2s: safebits = 0x7fff; break;
 541         case Bytecodes::_i2c: safebits = 0xffff; break;
 542       }
 543       // When casting a masked integer to a smaller signed type, if
 544       // the mask doesn't include the sign bit the cast isn't needed.
 545       if (safebits && (mask & ~safebits) == 0) {
 546         set_canonical(x->value());
 547       }
 548     }
 549   }
 550 
 551 }
 552 
 553 void Canonicalizer::do_NullCheck      (NullCheck*       x) {
 554   if (x->obj()->as_NewArray() != NULL || x->obj()->as_NewInstance() != NULL) {
 555     set_canonical(x->obj());
 556   } else {
 557     Constant* con = x->obj()->as_Constant();
 558     if (con) {
 559       ObjectType* c = con->type()->as_ObjectType();
 560       if (c && c->is_loaded()) {
 561         ObjectConstant* oc = c->as_ObjectConstant();
 562         if (!oc || !oc->value()->is_null_object()) {
 563           set_canonical(con);
 564         }
 565       }
 566     }
 567   }
 568 }
 569 
 570 void Canonicalizer::do_TypeCast       (TypeCast*        x) {}
 571 void Canonicalizer::do_Invoke         (Invoke*          x) {}
 572 void Canonicalizer::do_NewInstance    (NewInstance*     x) {}
 573 void Canonicalizer::do_NewTypeArray   (NewTypeArray*    x) {}
 574 void Canonicalizer::do_NewObjectArray (NewObjectArray*  x) {}
 575 void Canonicalizer::do_NewMultiArray  (NewMultiArray*   x) {}
 576 void Canonicalizer::do_CheckCast      (CheckCast*       x) {
 577   if (x->klass()->is_loaded()) {
 578     Value obj = x->obj();
 579     ciType* klass = obj->exact_type();
 580     if (klass == NULL) klass = obj->declared_type();
 581     if (klass != NULL && klass->is_loaded() && klass->is_subtype_of(x->klass())) {
 582       set_canonical(obj);
 583       return;
 584     }
 585     // checkcast of null returns null
 586     if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
 587       set_canonical(obj);
 588     }
 589   }
 590 }
 591 void Canonicalizer::do_InstanceOf     (InstanceOf*      x) {
 592   if (x->klass()->is_loaded()) {
 593     Value obj = x->obj();
 594     ciType* exact = obj->exact_type();
 595     if (exact != NULL && exact->is_loaded() && (obj->as_NewInstance() || obj->as_NewArray())) {
 596       set_constant(exact->is_subtype_of(x->klass()) ? 1 : 0);
 597       return;
 598     }
 599     // instanceof null returns false
 600     if (obj->as_Constant() && obj->type()->as_ObjectType()->constant_value()->is_null_object()) {
 601       set_constant(0);
 602     }
 603   }
 604 
 605 }
 606 void Canonicalizer::do_MonitorEnter   (MonitorEnter*    x) {}
 607 void Canonicalizer::do_MonitorExit    (MonitorExit*     x) {}
 608 void Canonicalizer::do_BlockBegin     (BlockBegin*      x) {}
 609 void Canonicalizer::do_Goto           (Goto*            x) {}
 610 
 611 
 612 static bool is_true(jlong x, If::Condition cond, jlong y) {
 613   switch (cond) {
 614     case If::eql: return x == y;
 615     case If::neq: return x != y;
 616     case If::lss: return x <  y;
 617     case If::leq: return x <= y;
 618     case If::gtr: return x >  y;
 619     case If::geq: return x >= y;
 620   }
 621   ShouldNotReachHere();
 622   return false;
 623 }
 624 
 625 static bool is_safepoint(BlockEnd* x, BlockBegin* sux) {
 626   // An Instruction with multiple successors, x, is replaced by a Goto
 627   // to a single successor, sux. Is a safepoint check needed = was the
 628   // instruction being replaced a safepoint and the single remaining
 629   // successor a back branch?
 630   return x->is_safepoint() && (sux->bci() < x->state_before()->bci());
 631 }
 632 
 633 void Canonicalizer::do_If(If* x) {
 634   // move const to right
 635   if (x->x()->type()->is_constant()) x->swap_operands();
 636   // simplify
 637   const Value l = x->x(); ValueType* lt = l->type();
 638   const Value r = x->y(); ValueType* rt = r->type();
 639 
 640   if (l == r && !lt->is_float_kind()) {
 641     // pattern: If (a cond a) => simplify to Goto
 642     BlockBegin* sux;
 643     switch (x->cond()) {
 644     case If::eql: sux = x->sux_for(true);  break;
 645     case If::neq: sux = x->sux_for(false); break;
 646     case If::lss: sux = x->sux_for(false); break;
 647     case If::leq: sux = x->sux_for(true);  break;
 648     case If::gtr: sux = x->sux_for(false); break;
 649     case If::geq: sux = x->sux_for(true);  break;
 650     }
 651     // If is a safepoint then the debug information should come from the state_before of the If.
 652     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 653     return;
 654   }
 655 
 656   if (lt->is_constant() && rt->is_constant()) {
 657     if (x->x()->as_Constant() != NULL) {
 658       // pattern: If (lc cond rc) => simplify to: Goto
 659       BlockBegin* sux = x->x()->as_Constant()->compare(x->cond(), x->y(),
 660                                                        x->sux_for(true),
 661                                                        x->sux_for(false));
 662       if (sux != NULL) {
 663         // If is a safepoint then the debug information should come from the state_before of the If.
 664         set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 665       }
 666     }
 667   } else if (rt->as_IntConstant() != NULL) {
 668     // pattern: If (l cond rc) => investigate further
 669     const jint rc = rt->as_IntConstant()->value();
 670     if (l->as_CompareOp() != NULL) {
 671       // pattern: If ((a cmp b) cond rc) => simplify to: If (x cond y) or: Goto
 672       CompareOp* cmp = l->as_CompareOp();
 673       bool unordered_is_less = cmp->op() == Bytecodes::_fcmpl || cmp->op() == Bytecodes::_dcmpl;
 674       BlockBegin* lss_sux = x->sux_for(is_true(-1, x->cond(), rc)); // successor for a < b
 675       BlockBegin* eql_sux = x->sux_for(is_true( 0, x->cond(), rc)); // successor for a = b
 676       BlockBegin* gtr_sux = x->sux_for(is_true(+1, x->cond(), rc)); // successor for a > b
 677       BlockBegin* nan_sux = unordered_is_less ? lss_sux : gtr_sux ; // successor for unordered
 678       // Note: At this point all successors (lss_sux, eql_sux, gtr_sux, nan_sux) are
 679       //       equal to x->tsux() or x->fsux(). Furthermore, nan_sux equals either
 680       //       lss_sux or gtr_sux.
 681       if (lss_sux == eql_sux && eql_sux == gtr_sux) {
 682         // all successors identical => simplify to: Goto
 683         set_canonical(new Goto(lss_sux, x->state_before(), x->is_safepoint()));
 684       } else {
 685         // two successors differ and two successors are the same => simplify to: If (x cmp y)
 686         // determine new condition & successors
 687         If::Condition cond;
 688         BlockBegin* tsux = NULL;
 689         BlockBegin* fsux = NULL;
 690              if (lss_sux == eql_sux) { cond = If::leq; tsux = lss_sux; fsux = gtr_sux; }
 691         else if (lss_sux == gtr_sux) { cond = If::neq; tsux = lss_sux; fsux = eql_sux; }
 692         else if (eql_sux == gtr_sux) { cond = If::geq; tsux = eql_sux; fsux = lss_sux; }
 693         else                         { ShouldNotReachHere();                           }
 694         If* canon = new If(cmp->x(), cond, nan_sux == tsux, cmp->y(), tsux, fsux, cmp->state_before(), x->is_safepoint());
 695         if (cmp->x() == cmp->y()) {
 696           do_If(canon);
 697         } else {
 698           if (compilation()->profile_branches()) {
 699             // TODO: If profiling, leave floating point comparisons unoptimized.
 700             // We currently do not support profiling of the unordered case.
 701             switch(cmp->op()) {
 702               case Bytecodes::_fcmpl: case Bytecodes::_fcmpg:
 703               case Bytecodes::_dcmpl: case Bytecodes::_dcmpg:
 704                 set_canonical(x);
 705                 return;
 706             }
 707           }
 708           set_bci(cmp->state_before()->bci());
 709           set_canonical(canon);
 710         }
 711       }
 712     } else if (l->as_InstanceOf() != NULL) {
 713       // NOTE: Code permanently disabled for now since it leaves the old InstanceOf
 714       //       instruction in the graph (it is pinned). Need to fix this at some point.
 715       //       It should also be left in the graph when generating a profiled method version or Goto
 716       //       has to know that it was an InstanceOf.
 717       return;
 718       // pattern: If ((obj instanceof klass) cond rc) => simplify to: IfInstanceOf or: Goto
 719       InstanceOf* inst = l->as_InstanceOf();
 720       BlockBegin* is_inst_sux = x->sux_for(is_true(1, x->cond(), rc)); // successor for instanceof == 1
 721       BlockBegin* no_inst_sux = x->sux_for(is_true(0, x->cond(), rc)); // successor for instanceof == 0
 722       if (is_inst_sux == no_inst_sux && inst->is_loaded()) {
 723         // both successors identical and klass is loaded => simplify to: Goto
 724         set_canonical(new Goto(is_inst_sux, x->state_before(), x->is_safepoint()));
 725       } else {
 726         // successors differ => simplify to: IfInstanceOf
 727         set_canonical(new IfInstanceOf(inst->klass(), inst->obj(), true, inst->state_before()->bci(), is_inst_sux, no_inst_sux));
 728       }
 729     }
 730   } else if (rt == objectNull && (l->as_NewInstance() || l->as_NewArray())) {
 731     if (x->cond() == Instruction::eql) {
 732       BlockBegin* sux = x->fsux();
 733       set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 734     } else {
 735       assert(x->cond() == Instruction::neq, "only other valid case");
 736       BlockBegin* sux = x->tsux();
 737       set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 738     }
 739   }
 740 }
 741 
 742 
 743 void Canonicalizer::do_TableSwitch(TableSwitch* x) {
 744   if (x->tag()->type()->is_constant()) {
 745     int v = x->tag()->type()->as_IntConstant()->value();
 746     BlockBegin* sux = x->default_sux();
 747     if (v >= x->lo_key() && v <= x->hi_key()) {
 748       sux = x->sux_at(v - x->lo_key());
 749     }
 750     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 751   } else if (x->number_of_sux() == 1) {
 752     // NOTE: Code permanently disabled for now since the switch statement's
 753     //       tag expression may produce side-effects in which case it must
 754     //       be executed.
 755     return;
 756     // simplify to Goto
 757     set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
 758   } else if (x->number_of_sux() == 2) {
 759     // NOTE: Code permanently disabled for now since it produces two new nodes
 760     //       (Constant & If) and the Canonicalizer cannot return them correctly
 761     //       yet. For now we copied the corresponding code directly into the
 762     //       GraphBuilder (i.e., we should never reach here).
 763     return;
 764     // simplify to If
 765     assert(x->lo_key() == x->hi_key(), "keys must be the same");
 766     Constant* key = new Constant(new IntConstant(x->lo_key()));
 767     set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
 768   }
 769 }
 770 
 771 
 772 void Canonicalizer::do_LookupSwitch(LookupSwitch* x) {
 773   if (x->tag()->type()->is_constant()) {
 774     int v = x->tag()->type()->as_IntConstant()->value();
 775     BlockBegin* sux = x->default_sux();
 776     for (int i = 0; i < x->length(); i++) {
 777       if (v == x->key_at(i)) {
 778         sux = x->sux_at(i);
 779       }
 780     }
 781     set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
 782   } else if (x->number_of_sux() == 1) {
 783     // NOTE: Code permanently disabled for now since the switch statement's
 784     //       tag expression may produce side-effects in which case it must
 785     //       be executed.
 786     return;
 787     // simplify to Goto
 788     set_canonical(new Goto(x->default_sux(), x->state_before(), x->is_safepoint()));
 789   } else if (x->number_of_sux() == 2) {
 790     // NOTE: Code permanently disabled for now since it produces two new nodes
 791     //       (Constant & If) and the Canonicalizer cannot return them correctly
 792     //       yet. For now we copied the corresponding code directly into the
 793     //       GraphBuilder (i.e., we should never reach here).
 794     return;
 795     // simplify to If
 796     assert(x->length() == 1, "length must be the same");
 797     Constant* key = new Constant(new IntConstant(x->key_at(0)));
 798     set_canonical(new If(x->tag(), If::eql, true, key, x->sux_at(0), x->default_sux(), x->state_before(), x->is_safepoint()));
 799   }
 800 }
 801 
 802 
 803 void Canonicalizer::do_Return         (Return*          x) {}
 804 void Canonicalizer::do_Throw          (Throw*           x) {}
 805 void Canonicalizer::do_Base           (Base*            x) {}
 806 void Canonicalizer::do_OsrEntry       (OsrEntry*        x) {}
 807 void Canonicalizer::do_ExceptionObject(ExceptionObject* x) {}
 808 
 809 static bool match_index_and_scale(Instruction*  instr,
 810                                   Instruction** index,
 811                                   int*          log2_scale,
 812                                   Instruction** instr_to_unpin) {
 813   *instr_to_unpin = NULL;
 814 
 815   // Skip conversion ops
 816   Convert* convert = instr->as_Convert();
 817   if (convert != NULL) {
 818     instr = convert->value();
 819   }
 820 
 821   ShiftOp* shift = instr->as_ShiftOp();
 822   if (shift != NULL) {
 823     if (shift->is_pinned()) {
 824       *instr_to_unpin = shift;
 825     }
 826     // Constant shift value?
 827     Constant* con = shift->y()->as_Constant();
 828     if (con == NULL) return false;
 829     // Well-known type and value?
 830     IntConstant* val = con->type()->as_IntConstant();
 831     if (val == NULL) return false;
 832     if (shift->x()->type() != intType) return false;
 833     *index = shift->x();
 834     int tmp_scale = val->value();
 835     if (tmp_scale >= 0 && tmp_scale < 4) {
 836       *log2_scale = tmp_scale;
 837       return true;
 838     } else {
 839       return false;
 840     }
 841   }
 842 
 843   ArithmeticOp* arith = instr->as_ArithmeticOp();
 844   if (arith != NULL) {
 845     if (arith->is_pinned()) {
 846       *instr_to_unpin = arith;
 847     }
 848     // Check for integer multiply
 849     if (arith->op() == Bytecodes::_imul) {
 850       // See if either arg is a known constant
 851       Constant* con = arith->x()->as_Constant();
 852       if (con != NULL) {
 853         *index = arith->y();
 854       } else {
 855         con = arith->y()->as_Constant();
 856         if (con == NULL) return false;
 857         *index = arith->x();
 858       }
 859       if ((*index)->type() != intType) return false;
 860       // Well-known type and value?
 861       IntConstant* val = con->type()->as_IntConstant();
 862       if (val == NULL) return false;
 863       switch (val->value()) {
 864       case 1: *log2_scale = 0; return true;
 865       case 2: *log2_scale = 1; return true;
 866       case 4: *log2_scale = 2; return true;
 867       case 8: *log2_scale = 3; return true;
 868       default:            return false;
 869       }
 870     }
 871   }
 872 
 873   // Unknown instruction sequence; don't touch it
 874   return false;
 875 }
 876 
 877 
 878 static bool match(UnsafeRawOp* x,
 879                   Instruction** base,
 880                   Instruction** index,
 881                   int*          log2_scale) {
 882   Instruction* instr_to_unpin = NULL;
 883   ArithmeticOp* root = x->base()->as_ArithmeticOp();
 884   if (root == NULL) return false;
 885   // Limit ourselves to addition for now
 886   if (root->op() != Bytecodes::_ladd) return false;
 887   // Try to find shift or scale op
 888   if (match_index_and_scale(root->y(), index, log2_scale, &instr_to_unpin)) {
 889     *base = root->x();
 890   } else if (match_index_and_scale(root->x(), index, log2_scale, &instr_to_unpin)) {
 891     *base = root->y();
 892   } else if (root->y()->as_Convert() != NULL) {
 893     Convert* convert = root->y()->as_Convert();
 894     if (convert->op() == Bytecodes::_i2l && convert->value()->type() == intType) {
 895       // pick base and index, setting scale at 1
 896       *base  = root->x();
 897       *index = convert->value();
 898       *log2_scale = 0;
 899     } else {
 900       return false;
 901     }
 902   } else {
 903     // doesn't match any expected sequences
 904     return false;
 905   }
 906 
 907   // If the value is pinned then it will be always be computed so
 908   // there's no profit to reshaping the expression.
 909   return !root->is_pinned();
 910 }
 911 
 912 
 913 void Canonicalizer::do_UnsafeRawOp(UnsafeRawOp* x) {
 914   Instruction* base = NULL;
 915   Instruction* index = NULL;
 916   int          log2_scale;
 917 
 918   if (match(x, &base, &index, &log2_scale)) {
 919     x->set_base(base);
 920     x->set_index(index);
 921     x->set_log2_scale(log2_scale);
 922     if (PrintUnsafeOptimization) {
 923       tty->print_cr("Canonicalizer: UnsafeRawOp id %d: base = id %d, index = id %d, log2_scale = %d",
 924                     x->id(), x->base()->id(), x->index()->id(), x->log2_scale());
 925     }
 926   }
 927 }
 928 
 929 void Canonicalizer::do_RoundFP(RoundFP* x) {}
 930 void Canonicalizer::do_UnsafeGetRaw(UnsafeGetRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
 931 void Canonicalizer::do_UnsafePutRaw(UnsafePutRaw* x) { if (OptimizeUnsafes) do_UnsafeRawOp(x); }
 932 void Canonicalizer::do_UnsafeGetObject(UnsafeGetObject* x) {}
 933 void Canonicalizer::do_UnsafePutObject(UnsafePutObject* x) {}
 934 void Canonicalizer::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {}
 935 void Canonicalizer::do_UnsafePrefetchRead (UnsafePrefetchRead*  x) {}
 936 void Canonicalizer::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {}
 937 void Canonicalizer::do_ProfileCall(ProfileCall* x) {}
 938 void Canonicalizer::do_ProfileInvoke(ProfileInvoke* x) {}
 939 void Canonicalizer::do_RuntimeCall(RuntimeCall* x) {}
 940 void Canonicalizer::do_MemBar(MemBar* x) {}