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