1 /*
   2  * Copyright (c) 1997, 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
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  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
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  24 
  25 #ifndef SHARE_VM_OPTO_CFGNODE_HPP
  26 #define SHARE_VM_OPTO_CFGNODE_HPP
  27 
  28 #include "opto/multnode.hpp"
  29 #include "opto/node.hpp"
  30 #include "opto/opcodes.hpp"
  31 #include "opto/type.hpp"
  32 
  33 // Portions of code courtesy of Clifford Click
  34 
  35 // Optimization - Graph Style
  36 
  37 class Matcher;
  38 class Node;
  39 class   RegionNode;
  40 class   TypeNode;
  41 class     PhiNode;
  42 class   GotoNode;
  43 class   MultiNode;
  44 class     MultiBranchNode;
  45 class       IfNode;
  46 class       PCTableNode;
  47 class         JumpNode;
  48 class         CatchNode;
  49 class       NeverBranchNode;
  50 class   ProjNode;
  51 class     CProjNode;
  52 class       IfTrueNode;
  53 class       IfFalseNode;
  54 class       CatchProjNode;
  55 class     JProjNode;
  56 class       JumpProjNode;
  57 class     SCMemProjNode;
  58 class PhaseIdealLoop;
  59 
  60 //------------------------------RegionNode-------------------------------------
  61 // The class of RegionNodes, which can be mapped to basic blocks in the
  62 // program.  Their inputs point to Control sources.  PhiNodes (described
  63 // below) have an input point to a RegionNode.  Merged data inputs to PhiNodes
  64 // correspond 1-to-1 with RegionNode inputs.  The zero input of a PhiNode is
  65 // the RegionNode, and the zero input of the RegionNode is itself.
  66 class RegionNode : public Node {
  67 public:
  68   // Node layout (parallels PhiNode):
  69   enum { Region,                // Generally points to self.
  70          Control                // Control arcs are [1..len)
  71   };
  72 
  73   RegionNode( uint required ) : Node(required) {
  74     init_class_id(Class_Region);
  75     init_req(0,this);
  76   }
  77 
  78   Node* is_copy() const {
  79     const Node* r = _in[Region];
  80     if (r == NULL)
  81       return nonnull_req();
  82     return NULL;  // not a copy!
  83   }
  84   PhiNode* has_phi() const;        // returns an arbitrary phi user, or NULL
  85   PhiNode* has_unique_phi() const; // returns the unique phi user, or NULL
  86   // Is this region node unreachable from root?
  87   bool is_unreachable_region(PhaseGVN *phase) const;
  88   virtual int Opcode() const;
  89   virtual bool pinned() const { return (const Node *)in(0) == this; }
  90   virtual bool  is_CFG   () const { return true; }
  91   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
  92   virtual bool depends_only_on_test() const { return false; }
  93   virtual const Type *bottom_type() const { return Type::CONTROL; }
  94   virtual const Type* Value(PhaseGVN* phase) const;
  95   virtual Node* Identity(PhaseGVN* phase);
  96   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
  97   virtual const RegMask &out_RegMask() const;
  98   bool try_clean_mem_phi(PhaseGVN *phase);
  99   bool optimize_trichotomy(PhaseIterGVN* igvn);
 100 };
 101 
 102 //------------------------------JProjNode--------------------------------------
 103 // jump projection for node that produces multiple control-flow paths
 104 class JProjNode : public ProjNode {
 105  public:
 106   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
 107   virtual int Opcode() const;
 108   virtual bool  is_CFG() const { return true; }
 109   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash
 110   virtual const Node* is_block_proj() const { return in(0); }
 111   virtual const RegMask& out_RegMask() const;
 112   virtual uint  ideal_reg() const { return 0; }
 113 };
 114 
 115 //------------------------------PhiNode----------------------------------------
 116 // PhiNodes merge values from different Control paths.  Slot 0 points to the
 117 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow
 118 // paths to the RegionNode.  For speed reasons (to avoid another pass) we
 119 // can turn PhiNodes into copys in-place by NULL'ing out their RegionNode
 120 // input in slot 0.
 121 class PhiNode : public TypeNode {
 122   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
 123   // The following fields are only used for data PhiNodes to indicate
 124   // that the PhiNode represents the value of a known instance field.
 125         int _inst_mem_id; // Instance memory id (node index of the memory Phi)
 126   const int _inst_id;     // Instance id of the memory slice.
 127   const int _inst_index;  // Alias index of the instance memory slice.
 128   // Array elements references have the same alias_idx but different offset.
 129   const int _inst_offset; // Offset of the instance memory slice.
 130   // Size is bigger to hold the _adr_type field.
 131   virtual uint hash() const;    // Check the type
 132   virtual uint cmp( const Node &n ) const;
 133   virtual uint size_of() const { return sizeof(*this); }
 134 
 135   // Determine if CMoveNode::is_cmove_id can be used at this join point.
 136   Node* is_cmove_id(PhaseTransform* phase, int true_path);
 137 
 138 public:
 139   // Node layout (parallels RegionNode):
 140   enum { Region,                // Control input is the Phi's region.
 141          Input                  // Input values are [1..len)
 142   };
 143 
 144   PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
 145            const int imid = -1,
 146            const int iid = TypeOopPtr::InstanceTop,
 147            const int iidx = Compile::AliasIdxTop,
 148            const int ioffs = Type::OffsetTop )
 149     : TypeNode(t,r->req()),
 150       _adr_type(at),
 151       _inst_mem_id(imid),
 152       _inst_id(iid),
 153       _inst_index(iidx),
 154       _inst_offset(ioffs)
 155   {
 156     init_class_id(Class_Phi);
 157     init_req(0, r);
 158     verify_adr_type();
 159   }
 160   // create a new phi with in edges matching r and set (initially) to x
 161   static PhiNode* make( Node* r, Node* x );
 162   // extra type arguments override the new phi's bottom_type and adr_type
 163   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
 164   // create a new phi with narrowed memory type
 165   PhiNode* slice_memory(const TypePtr* adr_type) const;
 166   PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
 167   // like make(r, x), but does not initialize the in edges to x
 168   static PhiNode* make_blank( Node* r, Node* x );
 169 
 170   // Accessors
 171   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
 172 
 173   Node* is_copy() const {
 174     // The node is a real phi if _in[0] is a Region node.
 175     DEBUG_ONLY(const Node* r = _in[Region];)
 176     assert(r != NULL && r->is_Region(), "Not valid control");
 177     return NULL;  // not a copy!
 178   }
 179 
 180   bool is_tripcount() const;
 181 
 182   // Determine a unique non-trivial input, if any.
 183   // Ignore casts if it helps.  Return NULL on failure.
 184   Node* unique_input(PhaseTransform *phase, bool uncast);
 185   Node* unique_input(PhaseTransform *phase) {
 186     Node* uin = unique_input(phase, false);
 187     if (uin == NULL) {
 188       uin = unique_input(phase, true);
 189     }
 190     return uin;
 191   }
 192 
 193   // Check for a simple dead loop.
 194   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
 195   LoopSafety simple_data_loop_check(Node *in) const;
 196   // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
 197   bool is_unsafe_data_reference(Node *in) const;
 198   int  is_diamond_phi(bool check_control_only = false) const;
 199   virtual int Opcode() const;
 200   virtual bool pinned() const { return in(0) != 0; }
 201   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
 202 
 203   void  set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
 204   const int inst_mem_id() const { return _inst_mem_id; }
 205   const int inst_id()     const { return _inst_id; }
 206   const int inst_index()  const { return _inst_index; }
 207   const int inst_offset() const { return _inst_offset; }
 208   bool is_same_inst_field(const Type* tp, int mem_id, int id, int index, int offset) {
 209     return type()->basic_type() == tp->basic_type() &&
 210            inst_mem_id() == mem_id &&
 211            inst_id()     == id     &&
 212            inst_index()  == index  &&
 213            inst_offset() == offset &&
 214            type()->higher_equal(tp);
 215   }
 216 
 217   virtual const Type* Value(PhaseGVN* phase) const;
 218   virtual Node* Identity(PhaseGVN* phase);
 219   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 220   virtual const RegMask &out_RegMask() const;
 221   virtual const RegMask &in_RegMask(uint) const;
 222 #ifndef PRODUCT
 223   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 224   virtual void dump_spec(outputStream *st) const;
 225 #endif
 226 #ifdef ASSERT
 227   void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
 228   void verify_adr_type(bool recursive = false) const;
 229 #else //ASSERT
 230   void verify_adr_type(bool recursive = false) const {}
 231 #endif //ASSERT
 232 };
 233 
 234 //------------------------------GotoNode---------------------------------------
 235 // GotoNodes perform direct branches.
 236 class GotoNode : public Node {
 237 public:
 238   GotoNode( Node *control ) : Node(control) {}
 239   virtual int Opcode() const;
 240   virtual bool pinned() const { return true; }
 241   virtual bool  is_CFG() const { return true; }
 242   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
 243   virtual const Node *is_block_proj() const { return this; }
 244   virtual bool depends_only_on_test() const { return false; }
 245   virtual const Type *bottom_type() const { return Type::CONTROL; }
 246   virtual const Type* Value(PhaseGVN* phase) const;
 247   virtual Node* Identity(PhaseGVN* phase);
 248   virtual const RegMask &out_RegMask() const;
 249 
 250 #ifndef PRODUCT
 251   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 252 #endif
 253 };
 254 
 255 //------------------------------CProjNode--------------------------------------
 256 // control projection for node that produces multiple control-flow paths
 257 class CProjNode : public ProjNode {
 258 public:
 259   CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
 260   virtual int Opcode() const;
 261   virtual bool  is_CFG() const { return true; }
 262   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
 263   virtual const Node *is_block_proj() const { return in(0); }
 264   virtual const RegMask &out_RegMask() const;
 265   virtual uint ideal_reg() const { return 0; }
 266 };
 267 
 268 //---------------------------MultiBranchNode-----------------------------------
 269 // This class defines a MultiBranchNode, a MultiNode which yields multiple
 270 // control values. These are distinguished from other types of MultiNodes
 271 // which yield multiple values, but control is always and only projection #0.
 272 class MultiBranchNode : public MultiNode {
 273 public:
 274   MultiBranchNode( uint required ) : MultiNode(required) {
 275     init_class_id(Class_MultiBranch);
 276   }
 277   // returns required number of users to be well formed.
 278   virtual int required_outcnt() const = 0;
 279 };
 280 
 281 //------------------------------IfNode-----------------------------------------
 282 // Output selected Control, based on a boolean test
 283 class IfNode : public MultiBranchNode {
 284   // Size is bigger to hold the probability field.  However, _prob does not
 285   // change the semantics so it does not appear in the hash & cmp functions.
 286   virtual uint size_of() const { return sizeof(*this); }
 287 
 288 private:
 289   // Helper methods for fold_compares
 290   bool cmpi_folds(PhaseIterGVN* igvn);
 291   bool is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn);
 292   bool has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail);
 293   bool has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn);
 294   Node* merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
 295   static void improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn);
 296   bool is_cmp_with_loadrange(ProjNode* proj);
 297   bool is_null_check(ProjNode* proj, PhaseIterGVN* igvn);
 298   bool is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn);
 299   void reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn);
 300   ProjNode* uncommon_trap_proj(CallStaticJavaNode*& call) const;
 301   bool fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
 302   static bool is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc);
 303 
 304 protected:
 305   ProjNode* range_check_trap_proj(int& flip, Node*& l, Node*& r);
 306   Node* Ideal_common(PhaseGVN *phase, bool can_reshape);
 307   Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
 308   Node* search_identical(int dist);
 309 
 310 public:
 311 
 312   // Degrees of branch prediction probability by order of magnitude:
 313   // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
 314   // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
 315 #define PROB_UNLIKELY_MAG(N)    (1e- ## N ## f)
 316 #define PROB_LIKELY_MAG(N)      (1.0f-PROB_UNLIKELY_MAG(N))
 317 
 318   // Maximum and minimum branch prediction probabilties
 319   // 1 in 1,000,000 (magnitude 6)
 320   //
 321   // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
 322   // they are used to distinguish different situations:
 323   //
 324   // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
 325   // very likely (unlikely) but with a concrete possibility of a rare
 326   // contrary case.  These constants would be used for pinning
 327   // measurements, and as measures for assertions that have high
 328   // confidence, but some evidence of occasional failure.
 329   //
 330   // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
 331   // there is no evidence at all that the contrary case has ever occurred.
 332 
 333 #define PROB_NEVER              PROB_UNLIKELY_MAG(6)
 334 #define PROB_ALWAYS             PROB_LIKELY_MAG(6)
 335 
 336 #define PROB_MIN                PROB_UNLIKELY_MAG(6)
 337 #define PROB_MAX                PROB_LIKELY_MAG(6)
 338 
 339   // Static branch prediction probabilities
 340   // 1 in 10 (magnitude 1)
 341 #define PROB_STATIC_INFREQUENT  PROB_UNLIKELY_MAG(1)
 342 #define PROB_STATIC_FREQUENT    PROB_LIKELY_MAG(1)
 343 
 344   // Fair probability 50/50
 345 #define PROB_FAIR               (0.5f)
 346 
 347   // Unknown probability sentinel
 348 #define PROB_UNKNOWN            (-1.0f)
 349 
 350   // Probability "constructors", to distinguish as a probability any manifest
 351   // constant without a names
 352 #define PROB_LIKELY(x)          ((float) (x))
 353 #define PROB_UNLIKELY(x)        (1.0f - (float)(x))
 354 
 355   // Other probabilities in use, but without a unique name, are documented
 356   // here for lack of a better place:
 357   //
 358   // 1 in 1000 probabilities (magnitude 3):
 359   //     threshold for converting to conditional move
 360   //     likelihood of null check failure if a null HAS been seen before
 361   //     likelihood of slow path taken in library calls
 362   //
 363   // 1 in 10,000 probabilities (magnitude 4):
 364   //     threshold for making an uncommon trap probability more extreme
 365   //     threshold for for making a null check implicit
 366   //     likelihood of needing a gc if eden top moves during an allocation
 367   //     likelihood of a predicted call failure
 368   //
 369   // 1 in 100,000 probabilities (magnitude 5):
 370   //     threshold for ignoring counts when estimating path frequency
 371   //     likelihood of FP clipping failure
 372   //     likelihood of catching an exception from a try block
 373   //     likelihood of null check failure if a null has NOT been seen before
 374   //
 375   // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
 376   // gen_subtype_check() and catch_inline_exceptions().
 377 
 378   float _prob;                  // Probability of true path being taken.
 379   float _fcnt;                  // Frequency counter
 380   IfNode( Node *control, Node *b, float p, float fcnt )
 381     : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
 382     init_class_id(Class_If);
 383     init_req(0,control);
 384     init_req(1,b);
 385   }
 386   virtual int Opcode() const;
 387   virtual bool pinned() const { return true; }
 388   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
 389   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 390   virtual const Type* Value(PhaseGVN* phase) const;
 391   virtual int required_outcnt() const { return 2; }
 392   virtual const RegMask &out_RegMask() const;
 393   Node* fold_compares(PhaseIterGVN* phase);
 394   static Node* up_one_dom(Node* curr, bool linear_only = false);
 395 
 396   // Takes the type of val and filters it through the test represented
 397   // by if_proj and returns a more refined type if one is produced.
 398   // Returns NULL is it couldn't improve the type.
 399   static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
 400 
 401 #ifndef PRODUCT
 402   virtual void dump_spec(outputStream *st) const;
 403   virtual void related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const;
 404 #endif
 405 };
 406 
 407 class RangeCheckNode : public IfNode {
 408 private:
 409   int is_range_check(Node* &range, Node* &index, jint &offset);
 410 
 411 public:
 412   RangeCheckNode(Node* control, Node *b, float p, float fcnt)
 413     : IfNode(control, b, p, fcnt) {
 414     init_class_id(Class_RangeCheck);
 415   }
 416 
 417   virtual int Opcode() const;
 418   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
 419 };
 420 
 421 class IfProjNode : public CProjNode {
 422 public:
 423   IfProjNode(IfNode *ifnode, uint idx) : CProjNode(ifnode,idx) {}
 424   virtual Node* Identity(PhaseGVN* phase);
 425 
 426 protected:
 427   // Type of If input when this branch is always taken
 428   virtual bool always_taken(const TypeTuple* t) const = 0;
 429 
 430 #ifndef PRODUCT
 431 public:
 432   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 433 #endif
 434 };
 435 
 436 class IfTrueNode : public IfProjNode {
 437 public:
 438   IfTrueNode( IfNode *ifnode ) : IfProjNode(ifnode,1) {
 439     init_class_id(Class_IfTrue);
 440   }
 441   virtual int Opcode() const;
 442 
 443 protected:
 444   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFTRUE; }
 445 };
 446 
 447 class IfFalseNode : public IfProjNode {
 448 public:
 449   IfFalseNode( IfNode *ifnode ) : IfProjNode(ifnode,0) {
 450     init_class_id(Class_IfFalse);
 451   }
 452   virtual int Opcode() const;
 453 
 454 protected:
 455   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFFALSE; }
 456 };
 457 
 458 
 459 //------------------------------PCTableNode------------------------------------
 460 // Build an indirect branch table.  Given a control and a table index,
 461 // control is passed to the Projection matching the table index.  Used to
 462 // implement switch statements and exception-handling capabilities.
 463 // Undefined behavior if passed-in index is not inside the table.
 464 class PCTableNode : public MultiBranchNode {
 465   virtual uint hash() const;    // Target count; table size
 466   virtual uint cmp( const Node &n ) const;
 467   virtual uint size_of() const { return sizeof(*this); }
 468 
 469 public:
 470   const uint _size;             // Number of targets
 471 
 472   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
 473     init_class_id(Class_PCTable);
 474     init_req(0, ctrl);
 475     init_req(1, idx);
 476   }
 477   virtual int Opcode() const;
 478   virtual const Type* Value(PhaseGVN* phase) const;
 479   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 480   virtual const Type *bottom_type() const;
 481   virtual bool pinned() const { return true; }
 482   virtual int required_outcnt() const { return _size; }
 483 };
 484 
 485 //------------------------------JumpNode---------------------------------------
 486 // Indirect branch.  Uses PCTable above to implement a switch statement.
 487 // It emits as a table load and local branch.
 488 class JumpNode : public PCTableNode {
 489   virtual uint size_of() const { return sizeof(*this); }
 490 public:
 491   float* _probs; // probability of each projection
 492   float _fcnt;   // total number of times this Jump was executed
 493   JumpNode( Node* control, Node* switch_val, uint size, float* probs, float cnt)
 494     : PCTableNode(control, switch_val, size),
 495       _probs(probs), _fcnt(cnt) {
 496     init_class_id(Class_Jump);
 497   }
 498   virtual int   Opcode() const;
 499   virtual const RegMask& out_RegMask() const;
 500   virtual const Node* is_block_proj() const { return this; }
 501 #ifndef PRODUCT
 502   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 503 #endif
 504 };
 505 
 506 class JumpProjNode : public JProjNode {
 507   virtual uint hash() const;
 508   virtual uint cmp( const Node &n ) const;
 509   virtual uint size_of() const { return sizeof(*this); }
 510 
 511  private:
 512   const int  _dest_bci;
 513   const uint _proj_no;
 514   const int  _switch_val;
 515  public:
 516   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
 517     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
 518     init_class_id(Class_JumpProj);
 519   }
 520 
 521   virtual int Opcode() const;
 522   virtual const Type* bottom_type() const { return Type::CONTROL; }
 523   int  dest_bci()    const { return _dest_bci; }
 524   int  switch_val()  const { return _switch_val; }
 525   uint proj_no()     const { return _proj_no; }
 526 #ifndef PRODUCT
 527   virtual void dump_spec(outputStream *st) const;
 528   virtual void dump_compact_spec(outputStream *st) const;
 529   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 530 #endif
 531 };
 532 
 533 //------------------------------CatchNode--------------------------------------
 534 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by
 535 // a just-prior call.  Looks like a PCTableNode but emits no code - just the
 536 // table.  The table lookup and branch is implemented by RethrowNode.
 537 class CatchNode : public PCTableNode {
 538 public:
 539   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
 540     init_class_id(Class_Catch);
 541   }
 542   virtual int Opcode() const;
 543   virtual const Type* Value(PhaseGVN* phase) const;
 544 };
 545 
 546 // CatchProjNode controls which exception handler is targetted after a call.
 547 // It is passed in the bci of the target handler, or no_handler_bci in case
 548 // the projection doesn't lead to an exception handler.
 549 class CatchProjNode : public CProjNode {
 550   virtual uint hash() const;
 551   virtual uint cmp( const Node &n ) const;
 552   virtual uint size_of() const { return sizeof(*this); }
 553 
 554 private:
 555   const int _handler_bci;
 556 
 557 public:
 558   enum {
 559     fall_through_index =  0,      // the fall through projection index
 560     catch_all_index    =  1,      // the projection index for catch-alls
 561     no_handler_bci     = -1       // the bci for fall through or catch-all projs
 562   };
 563 
 564   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
 565     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
 566     init_class_id(Class_CatchProj);
 567     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
 568   }
 569 
 570   virtual int Opcode() const;
 571   virtual Node* Identity(PhaseGVN* phase);
 572   virtual const Type *bottom_type() const { return Type::CONTROL; }
 573   int  handler_bci() const        { return _handler_bci; }
 574   bool is_handler_proj() const    { return _handler_bci >= 0; }
 575 #ifndef PRODUCT
 576   virtual void dump_spec(outputStream *st) const;
 577 #endif
 578 };
 579 
 580 
 581 //---------------------------------CreateExNode--------------------------------
 582 // Helper node to create the exception coming back from a call
 583 class CreateExNode : public TypeNode {
 584 public:
 585   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
 586     init_req(0, control);
 587     init_req(1, i_o);
 588   }
 589   virtual int Opcode() const;
 590   virtual Node* Identity(PhaseGVN* phase);
 591   virtual bool pinned() const { return true; }
 592   uint match_edge(uint idx) const { return 0; }
 593   virtual uint ideal_reg() const { return Op_RegP; }
 594 };
 595 
 596 //------------------------------NeverBranchNode-------------------------------
 597 // The never-taken branch.  Used to give the appearance of exiting infinite
 598 // loops to those algorithms that like all paths to be reachable.  Encodes
 599 // empty.
 600 class NeverBranchNode : public MultiBranchNode {
 601 public:
 602   NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
 603   virtual int Opcode() const;
 604   virtual bool pinned() const { return true; };
 605   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
 606   virtual const Type* Value(PhaseGVN* phase) const;
 607   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 608   virtual int required_outcnt() const { return 2; }
 609   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
 610   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
 611 #ifndef PRODUCT
 612   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
 613 #endif
 614 };
 615 
 616 #endif // SHARE_VM_OPTO_CFGNODE_HPP