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
  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.
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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 };
 100 
 101 //------------------------------JProjNode--------------------------------------
 102 // jump projection for node that produces multiple control-flow paths
 103 class JProjNode : public ProjNode {
 104  public:
 105   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
 106   virtual int Opcode() const;
 107   virtual bool  is_CFG() const { return true; }
 108   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash
 109   virtual const Node* is_block_proj() const { return in(0); }
 110   virtual const RegMask& out_RegMask() const;
 111   virtual uint  ideal_reg() const { return 0; }
 112 };
 113 
 114 //------------------------------PhiNode----------------------------------------
 115 // PhiNodes merge values from different Control paths.  Slot 0 points to the
 116 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow
 117 // paths to the RegionNode.  For speed reasons (to avoid another pass) we
 118 // can turn PhiNodes into copys in-place by NULL'ing out their RegionNode
 119 // input in slot 0.
 120 class PhiNode : public TypeNode {
 121   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
 122   // The following fields are only used for data PhiNodes to indicate
 123   // that the PhiNode represents the value of a known instance field.
 124         int _inst_mem_id; // Instance memory id (node index of the memory Phi)
 125   const int _inst_id;     // Instance id of the memory slice.
 126   const int _inst_index;  // Alias index of the instance memory slice.
 127   // Array elements references have the same alias_idx but different offset.
 128   const int _inst_offset; // Offset of the instance memory slice.
 129   // Size is bigger to hold the _adr_type field.
 130   virtual uint hash() const;    // Check the type
 131   virtual uint cmp( const Node &n ) const;
 132   virtual uint size_of() const { return sizeof(*this); }
 133 
 134   // Determine if CMoveNode::is_cmove_id can be used at this join point.
 135   Node* is_cmove_id(PhaseTransform* phase, int true_path);
 136 
 137 public:
 138   // Node layout (parallels RegionNode):
 139   enum { Region,                // Control input is the Phi's region.
 140          Input                  // Input values are [1..len)
 141   };
 142 
 143   PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
 144            const int imid = -1,
 145            const int iid = TypeOopPtr::InstanceTop,
 146            const int iidx = Compile::AliasIdxTop,
 147            const int ioffs = Type::OffsetTop )
 148     : TypeNode(t,r->req()),
 149       _adr_type(at),
 150       _inst_mem_id(imid),
 151       _inst_id(iid),
 152       _inst_index(iidx),
 153       _inst_offset(ioffs)
 154   {
 155     init_class_id(Class_Phi);
 156     init_req(0, r);
 157     verify_adr_type();
 158   }
 159   // create a new phi with in edges matching r and set (initially) to x
 160   static PhiNode* make( Node* r, Node* x );
 161   // extra type arguments override the new phi's bottom_type and adr_type
 162   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
 163   // create a new phi with narrowed memory type
 164   PhiNode* slice_memory(const TypePtr* adr_type) const;
 165   PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
 166   // like make(r, x), but does not initialize the in edges to x
 167   static PhiNode* make_blank( Node* r, Node* x );
 168 
 169   // Accessors
 170   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
 171 
 172   Node* is_copy() const {
 173     // The node is a real phi if _in[0] is a Region node.
 174     DEBUG_ONLY(const Node* r = _in[Region];)
 175     assert(r != NULL && r->is_Region(), "Not valid control");
 176     return NULL;  // not a copy!
 177   }
 178 
 179   bool is_tripcount() const;
 180 
 181   // Determine a unique non-trivial input, if any.
 182   // Ignore casts if it helps.  Return NULL on failure.
 183   Node* unique_input(PhaseTransform *phase, bool uncast);
 184   Node* unique_input(PhaseTransform *phase) {
 185     Node* uin = unique_input(phase, false);
 186     if (uin == NULL) {
 187       uin = unique_input(phase, true);
 188     }
 189     return uin;
 190   }
 191 
 192   // Check for a simple dead loop.
 193   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
 194   LoopSafety simple_data_loop_check(Node *in) const;
 195   // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
 196   bool is_unsafe_data_reference(Node *in) const;
 197   int  is_diamond_phi(bool check_control_only = false) const;
 198   virtual int Opcode() const;
 199   virtual bool pinned() const { return in(0) != 0; }
 200   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
 201 
 202   void  set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
 203   const int inst_mem_id() const { return _inst_mem_id; }
 204   const int inst_id()     const { return _inst_id; }
 205   const int inst_index()  const { return _inst_index; }
 206   const int inst_offset() const { return _inst_offset; }
 207   bool is_same_inst_field(const Type* tp, int mem_id, int id, int index, int offset) {
 208     return type()->basic_type() == tp->basic_type() &&
 209            inst_mem_id() == mem_id &&
 210            inst_id()     == id     &&
 211            inst_index()  == index  &&
 212            inst_offset() == offset &&
 213            type()->higher_equal(tp);
 214   }
 215 
 216   virtual const Type* Value(PhaseGVN* phase) const;
 217   virtual Node* Identity(PhaseGVN* phase);
 218   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 219   virtual const RegMask &out_RegMask() const;
 220   virtual const RegMask &in_RegMask(uint) const;
 221 #ifndef PRODUCT
 222   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 223   virtual void dump_spec(outputStream *st) const;
 224 #endif
 225 #ifdef ASSERT
 226   void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
 227   void verify_adr_type(bool recursive = false) const;
 228 #else //ASSERT
 229   void verify_adr_type(bool recursive = false) const {}
 230 #endif //ASSERT
 231 };
 232 
 233 //------------------------------GotoNode---------------------------------------
 234 // GotoNodes perform direct branches.
 235 class GotoNode : public Node {
 236 public:
 237   GotoNode( Node *control ) : Node(control) {}
 238   virtual int Opcode() const;
 239   virtual bool pinned() const { return true; }
 240   virtual bool  is_CFG() const { return true; }
 241   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
 242   virtual const Node *is_block_proj() const { return this; }
 243   virtual bool depends_only_on_test() const { return false; }
 244   virtual const Type *bottom_type() const { return Type::CONTROL; }
 245   virtual const Type* Value(PhaseGVN* phase) const;
 246   virtual Node* Identity(PhaseGVN* phase);
 247   virtual const RegMask &out_RegMask() const;
 248 
 249 #ifndef PRODUCT
 250   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 251 #endif
 252 };
 253 
 254 //------------------------------CProjNode--------------------------------------
 255 // control projection for node that produces multiple control-flow paths
 256 class CProjNode : public ProjNode {
 257 public:
 258   CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
 259   virtual int Opcode() const;
 260   virtual bool  is_CFG() const { return true; }
 261   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
 262   virtual const Node *is_block_proj() const { return in(0); }
 263   virtual const RegMask &out_RegMask() const;
 264   virtual uint ideal_reg() const { return 0; }
 265 };
 266 
 267 //---------------------------MultiBranchNode-----------------------------------
 268 // This class defines a MultiBranchNode, a MultiNode which yields multiple
 269 // control values. These are distinguished from other types of MultiNodes
 270 // which yield multiple values, but control is always and only projection #0.
 271 class MultiBranchNode : public MultiNode {
 272 public:
 273   MultiBranchNode( uint required ) : MultiNode(required) {
 274     init_class_id(Class_MultiBranch);
 275   }
 276   // returns required number of users to be well formed.
 277   virtual int required_outcnt() const = 0;
 278 };
 279 
 280 //------------------------------IfNode-----------------------------------------
 281 // Output selected Control, based on a boolean test
 282 class IfNode : public MultiBranchNode {
 283   // Size is bigger to hold the probability field.  However, _prob does not
 284   // change the semantics so it does not appear in the hash & cmp functions.
 285   virtual uint size_of() const { return sizeof(*this); }
 286 
 287 private:
 288   // Helper methods for fold_compares
 289   bool cmpi_folds(PhaseIterGVN* igvn);
 290   bool is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn);
 291   bool has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail);
 292   bool has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn);
 293   Node* merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
 294   static void improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn);
 295   bool is_cmp_with_loadrange(ProjNode* proj);
 296   bool is_null_check(ProjNode* proj, PhaseIterGVN* igvn);
 297   bool is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn);
 298   void reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn);
 299   ProjNode* uncommon_trap_proj(CallStaticJavaNode*& call) const;
 300   bool fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
 301   static bool is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc);
 302 
 303 protected:
 304   ProjNode* range_check_trap_proj(int& flip, Node*& l, Node*& r);
 305   Node* Ideal_common(PhaseGVN *phase, bool can_reshape);
 306   Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
 307   Node* search_identical(int dist);
 308 
 309 public:
 310 
 311   // Degrees of branch prediction probability by order of magnitude:
 312   // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
 313   // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
 314 #define PROB_UNLIKELY_MAG(N)    (1e- ## N ## f)
 315 #define PROB_LIKELY_MAG(N)      (1.0f-PROB_UNLIKELY_MAG(N))
 316 
 317   // Maximum and minimum branch prediction probabilties
 318   // 1 in 1,000,000 (magnitude 6)
 319   //
 320   // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
 321   // they are used to distinguish different situations:
 322   //
 323   // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
 324   // very likely (unlikely) but with a concrete possibility of a rare
 325   // contrary case.  These constants would be used for pinning
 326   // measurements, and as measures for assertions that have high
 327   // confidence, but some evidence of occasional failure.
 328   //
 329   // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
 330   // there is no evidence at all that the contrary case has ever occurred.
 331 
 332 #define PROB_NEVER              PROB_UNLIKELY_MAG(6)
 333 #define PROB_ALWAYS             PROB_LIKELY_MAG(6)
 334 
 335 #define PROB_MIN                PROB_UNLIKELY_MAG(6)
 336 #define PROB_MAX                PROB_LIKELY_MAG(6)
 337 
 338   // Static branch prediction probabilities
 339   // 1 in 10 (magnitude 1)
 340 #define PROB_STATIC_INFREQUENT  PROB_UNLIKELY_MAG(1)
 341 #define PROB_STATIC_FREQUENT    PROB_LIKELY_MAG(1)
 342 
 343   // Fair probability 50/50
 344 #define PROB_FAIR               (0.5f)
 345 
 346   // Unknown probability sentinel
 347 #define PROB_UNKNOWN            (-1.0f)
 348 
 349   // Probability "constructors", to distinguish as a probability any manifest
 350   // constant without a names
 351 #define PROB_LIKELY(x)          ((float) (x))
 352 #define PROB_UNLIKELY(x)        (1.0f - (float)(x))
 353 
 354   // Other probabilities in use, but without a unique name, are documented
 355   // here for lack of a better place:
 356   //
 357   // 1 in 1000 probabilities (magnitude 3):
 358   //     threshold for converting to conditional move
 359   //     likelihood of null check failure if a null HAS been seen before
 360   //     likelihood of slow path taken in library calls
 361   //
 362   // 1 in 10,000 probabilities (magnitude 4):
 363   //     threshold for making an uncommon trap probability more extreme
 364   //     threshold for for making a null check implicit
 365   //     likelihood of needing a gc if eden top moves during an allocation
 366   //     likelihood of a predicted call failure
 367   //
 368   // 1 in 100,000 probabilities (magnitude 5):
 369   //     threshold for ignoring counts when estimating path frequency
 370   //     likelihood of FP clipping failure
 371   //     likelihood of catching an exception from a try block
 372   //     likelihood of null check failure if a null has NOT been seen before
 373   //
 374   // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
 375   // gen_subtype_check() and catch_inline_exceptions().
 376 
 377   float _prob;                  // Probability of true path being taken.
 378   float _fcnt;                  // Frequency counter
 379   IfNode( Node *control, Node *b, float p, float fcnt )
 380     : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
 381     init_class_id(Class_If);
 382     init_req(0,control);
 383     init_req(1,b);
 384   }
 385   virtual int Opcode() const;
 386   virtual bool pinned() const { return true; }
 387   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
 388   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 389   virtual const Type* Value(PhaseGVN* phase) const;
 390   virtual int required_outcnt() const { return 2; }
 391   virtual const RegMask &out_RegMask() const;
 392   Node* fold_compares(PhaseIterGVN* phase);
 393   static Node* up_one_dom(Node* curr, bool linear_only = false);

 394 
 395   // Takes the type of val and filters it through the test represented
 396   // by if_proj and returns a more refined type if one is produced.
 397   // Returns NULL is it couldn't improve the type.
 398   static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
 399 
 400 #ifndef PRODUCT
 401   virtual void dump_spec(outputStream *st) const;
 402   virtual void related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const;
 403 #endif
 404 };
 405 
 406 class RangeCheckNode : public IfNode {
 407 private:
 408   int is_range_check(Node* &range, Node* &index, jint &offset);
 409 
 410 public:
 411   RangeCheckNode(Node* control, Node *b, float p, float fcnt)
 412     : IfNode(control, b, p, fcnt) {
 413     init_class_id(Class_RangeCheck);
 414   }
 415 
 416   virtual int Opcode() const;
 417   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
 418 };
 419 
 420 class IfProjNode : public CProjNode {
 421 public:
 422   IfProjNode(IfNode *ifnode, uint idx) : CProjNode(ifnode,idx) {}
 423   virtual Node* Identity(PhaseGVN* phase);
 424 
 425 protected:
 426   // Type of If input when this branch is always taken
 427   virtual bool always_taken(const TypeTuple* t) const = 0;
 428 
 429 #ifndef PRODUCT
 430 public:
 431   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 432 #endif
 433 };
 434 
 435 class IfTrueNode : public IfProjNode {
 436 public:
 437   IfTrueNode( IfNode *ifnode ) : IfProjNode(ifnode,1) {
 438     init_class_id(Class_IfTrue);
 439   }
 440   virtual int Opcode() const;
 441 
 442 protected:
 443   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFTRUE; }
 444 };
 445 
 446 class IfFalseNode : public IfProjNode {
 447 public:
 448   IfFalseNode( IfNode *ifnode ) : IfProjNode(ifnode,0) {
 449     init_class_id(Class_IfFalse);
 450   }
 451   virtual int Opcode() const;
 452 
 453 protected:
 454   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFFALSE; }
 455 };
 456 
 457 
 458 //------------------------------PCTableNode------------------------------------
 459 // Build an indirect branch table.  Given a control and a table index,
 460 // control is passed to the Projection matching the table index.  Used to
 461 // implement switch statements and exception-handling capabilities.
 462 // Undefined behavior if passed-in index is not inside the table.
 463 class PCTableNode : public MultiBranchNode {
 464   virtual uint hash() const;    // Target count; table size
 465   virtual uint cmp( const Node &n ) const;
 466   virtual uint size_of() const { return sizeof(*this); }
 467 
 468 public:
 469   const uint _size;             // Number of targets
 470 
 471   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
 472     init_class_id(Class_PCTable);
 473     init_req(0, ctrl);
 474     init_req(1, idx);
 475   }
 476   virtual int Opcode() const;
 477   virtual const Type* Value(PhaseGVN* phase) const;
 478   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 479   virtual const Type *bottom_type() const;
 480   virtual bool pinned() const { return true; }
 481   virtual int required_outcnt() const { return _size; }
 482 };
 483 
 484 //------------------------------JumpNode---------------------------------------
 485 // Indirect branch.  Uses PCTable above to implement a switch statement.
 486 // It emits as a table load and local branch.
 487 class JumpNode : public PCTableNode {
 488   virtual uint size_of() const { return sizeof(*this); }
 489 public:
 490   float* _probs; // probability of each projection
 491   float _fcnt;   // total number of times this Jump was executed
 492   JumpNode( Node* control, Node* switch_val, uint size, float* probs, float cnt)
 493     : PCTableNode(control, switch_val, size),
 494       _probs(probs), _fcnt(cnt) {
 495     init_class_id(Class_Jump);
 496   }
 497   virtual int   Opcode() const;
 498   virtual const RegMask& out_RegMask() const;
 499   virtual const Node* is_block_proj() const { return this; }
 500 #ifndef PRODUCT
 501   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 502 #endif
 503 };
 504 
 505 class JumpProjNode : public JProjNode {
 506   virtual uint hash() const;
 507   virtual uint cmp( const Node &n ) const;
 508   virtual uint size_of() const { return sizeof(*this); }
 509 
 510  private:
 511   const int  _dest_bci;
 512   const uint _proj_no;
 513   const int  _switch_val;
 514  public:
 515   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
 516     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
 517     init_class_id(Class_JumpProj);
 518   }
 519 
 520   virtual int Opcode() const;
 521   virtual const Type* bottom_type() const { return Type::CONTROL; }
 522   int  dest_bci()    const { return _dest_bci; }
 523   int  switch_val()  const { return _switch_val; }
 524   uint proj_no()     const { return _proj_no; }
 525 #ifndef PRODUCT
 526   virtual void dump_spec(outputStream *st) const;
 527   virtual void dump_compact_spec(outputStream *st) const;
 528   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
 529 #endif
 530 };
 531 
 532 //------------------------------CatchNode--------------------------------------
 533 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by
 534 // a just-prior call.  Looks like a PCTableNode but emits no code - just the
 535 // table.  The table lookup and branch is implemented by RethrowNode.
 536 class CatchNode : public PCTableNode {
 537 public:
 538   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
 539     init_class_id(Class_Catch);
 540   }
 541   virtual int Opcode() const;
 542   virtual const Type* Value(PhaseGVN* phase) const;
 543 };
 544 
 545 // CatchProjNode controls which exception handler is targetted after a call.
 546 // It is passed in the bci of the target handler, or no_handler_bci in case
 547 // the projection doesn't lead to an exception handler.
 548 class CatchProjNode : public CProjNode {
 549   virtual uint hash() const;
 550   virtual uint cmp( const Node &n ) const;
 551   virtual uint size_of() const { return sizeof(*this); }
 552 
 553 private:
 554   const int _handler_bci;
 555 
 556 public:
 557   enum {
 558     fall_through_index =  0,      // the fall through projection index
 559     catch_all_index    =  1,      // the projection index for catch-alls
 560     no_handler_bci     = -1       // the bci for fall through or catch-all projs
 561   };
 562 
 563   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
 564     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
 565     init_class_id(Class_CatchProj);
 566     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
 567   }
 568 
 569   virtual int Opcode() const;
 570   virtual Node* Identity(PhaseGVN* phase);
 571   virtual const Type *bottom_type() const { return Type::CONTROL; }
 572   int  handler_bci() const        { return _handler_bci; }
 573   bool is_handler_proj() const    { return _handler_bci >= 0; }
 574 #ifndef PRODUCT
 575   virtual void dump_spec(outputStream *st) const;
 576 #endif
 577 };
 578 
 579 
 580 //---------------------------------CreateExNode--------------------------------
 581 // Helper node to create the exception coming back from a call
 582 class CreateExNode : public TypeNode {
 583 public:
 584   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
 585     init_req(0, control);
 586     init_req(1, i_o);
 587   }
 588   virtual int Opcode() const;
 589   virtual Node* Identity(PhaseGVN* phase);
 590   virtual bool pinned() const { return true; }
 591   uint match_edge(uint idx) const { return 0; }
 592   virtual uint ideal_reg() const { return Op_RegP; }
 593 };
 594 
 595 //------------------------------NeverBranchNode-------------------------------
 596 // The never-taken branch.  Used to give the appearance of exiting infinite
 597 // loops to those algorithms that like all paths to be reachable.  Encodes
 598 // empty.
 599 class NeverBranchNode : public MultiBranchNode {
 600 public:
 601   NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
 602   virtual int Opcode() const;
 603   virtual bool pinned() const { return true; };
 604   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
 605   virtual const Type* Value(PhaseGVN* phase) const;
 606   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 607   virtual int required_outcnt() const { return 2; }
 608   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
 609   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
 610 #ifndef PRODUCT
 611   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
 612 #endif
 613 };
 614 
 615 #endif // SHARE_VM_OPTO_CFGNODE_HPP
--- EOF ---