1 /*
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  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.
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  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  *
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 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
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 24 
 25 #ifndef SHARE_OPTO_CFGNODE_HPP
 26 #define SHARE_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 private:
 68   bool _is_unreachable_region;
 69 
 70   bool is_possible_unsafe_loop(const PhaseGVN* phase) const;
 71   bool is_unreachable_from_root(const PhaseGVN* phase) const;
 72 public:
 73   // Node layout (parallels PhiNode):
 74   enum { Region,                // Generally points to self.
 75          Control                // Control arcs are [1..len)
 76   };
 77 
 78   RegionNode(uint required) : Node(required), _is_unreachable_region(false) {
 79     init_class_id(Class_Region);
 80     init_req(0, this);
 81   }
 82 
 83   Node* is_copy() const {
 84     const Node* r = _in[Region];
 85     if (r == NULL)
 86       return nonnull_req();
 87     return NULL;  // not a copy!
 88   }
 89   PhiNode* has_phi() const;        // returns an arbitrary phi user, or NULL
 90   PhiNode* has_unique_phi() const; // returns the unique phi user, or NULL
 91   // Is this region node unreachable from root?
 92   bool is_unreachable_region(const PhaseGVN* phase);
 93   virtual int Opcode() const;
 94   virtual uint size_of() const { return sizeof(*this); }
 95   virtual bool pinned() const { return (const Node*)in(0) == this; }
 96   virtual bool is_CFG() const { return true; }
 97   virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
 98   virtual bool depends_only_on_test() const { return false; }
 99   virtual const Type* bottom_type() const { return Type::CONTROL; }
100   virtual const Type* Value(PhaseGVN* phase) const;
101   virtual Node* Identity(PhaseGVN* phase);
102   virtual Node* Ideal(PhaseGVN* phase, bool can_reshape);
103   virtual const RegMask &out_RegMask() const;
104   bool try_clean_mem_phi(PhaseGVN* phase);
105   bool optimize_trichotomy(PhaseIterGVN* igvn);
106 };
107 
108 //------------------------------JProjNode--------------------------------------
109 // jump projection for node that produces multiple control-flow paths
110 class JProjNode : public ProjNode {
111  public:
112   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
113   virtual int Opcode() const;
114   virtual bool  is_CFG() const { return true; }
115   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash
116   virtual const Node* is_block_proj() const { return in(0); }
117   virtual const RegMask& out_RegMask() const;
118   virtual uint  ideal_reg() const { return 0; }
119 };
120 
121 //------------------------------PhiNode----------------------------------------
122 // PhiNodes merge values from different Control paths.  Slot 0 points to the
123 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow
124 // paths to the RegionNode.
125 class PhiNode : public TypeNode {
126   friend class PhaseRenumberLive;
127 
128   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
129   // The following fields are only used for data PhiNodes to indicate
130   // that the PhiNode represents the value of a known instance field.
131         int _inst_mem_id; // Instance memory id (node index of the memory Phi)
132         int _inst_id;     // Instance id of the memory slice.
133   const int _inst_index;  // Alias index of the instance memory slice.
134   // Array elements references have the same alias_idx but different offset.
135   const int _inst_offset; // Offset of the instance memory slice.
136   // Size is bigger to hold the _adr_type field.
137   virtual uint hash() const;    // Check the type
138   virtual bool cmp( const Node &n ) const;
139   virtual uint size_of() const { return sizeof(*this); }
140 
141   // Determine if CMoveNode::is_cmove_id can be used at this join point.
142   Node* is_cmove_id(PhaseTransform* phase, int true_path);
143   bool wait_for_region_igvn(PhaseGVN* phase);
144   bool is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase);
145 
146   static Node* clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn);
147   static Node* merge_through_phi(Node* root_phi, PhaseIterGVN* igvn);
148 
149 public:
150   // Node layout (parallels RegionNode):
151   enum { Region,                // Control input is the Phi's region.
152          Input                  // Input values are [1..len)
153   };
154 
155   PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
156            const int imid = -1,
157            const int iid = TypeOopPtr::InstanceTop,
158            const int iidx = Compile::AliasIdxTop,
159            const int ioffs = Type::OffsetTop )
160     : TypeNode(t,r->req()),
161       _adr_type(at),
162       _inst_mem_id(imid),
163       _inst_id(iid),
164       _inst_index(iidx),
165       _inst_offset(ioffs)
166   {
167     init_class_id(Class_Phi);
168     init_req(0, r);
169     verify_adr_type();
170   }
171   // create a new phi with in edges matching r and set (initially) to x
172   static PhiNode* make( Node* r, Node* x );
173   // extra type arguments override the new phi's bottom_type and adr_type
174   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
175   // create a new phi with narrowed memory type
176   PhiNode* slice_memory(const TypePtr* adr_type) const;
177   PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
178   // like make(r, x), but does not initialize the in edges to x
179   static PhiNode* make_blank( Node* r, Node* x );
180 
181   // Accessors
182   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
183 
184   bool is_tripcount(BasicType bt) const;
185 
186   // Determine a unique non-trivial input, if any.
187   // Ignore casts if it helps.  Return NULL on failure.
188   Node* unique_input(PhaseTransform *phase, bool uncast);
189   Node* unique_input(PhaseTransform *phase) {
190     Node* uin = unique_input(phase, false);
191     if (uin == NULL) {
192       uin = unique_input(phase, true);
193     }
194     return uin;
195   }
196 
197   // Check for a simple dead loop.
198   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
199   LoopSafety simple_data_loop_check(Node *in) const;
200   // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
201   bool is_unsafe_data_reference(Node *in) const;
202   int  is_diamond_phi(bool check_control_only = false) const;
203   virtual int Opcode() const;
204   virtual bool pinned() const { return in(0) != 0; }
205   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
206 
207   void  set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
208   const int inst_mem_id() const { return _inst_mem_id; }
209   const int inst_id()     const { return _inst_id; }
210   const int inst_index()  const { return _inst_index; }
211   const int inst_offset() const { return _inst_offset; }
212   bool is_same_inst_field(const Type* tp, int mem_id, int id, int index, int offset) {
213     return type()->basic_type() == tp->basic_type() &&
214            inst_mem_id() == mem_id &&
215            inst_id()     == id     &&
216            inst_index()  == index  &&
217            inst_offset() == offset &&
218            type()->higher_equal(tp);
219   }
220 
221   virtual const Type* Value(PhaseGVN* phase) const;
222   virtual Node* Identity(PhaseGVN* phase);
223   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
224   virtual const RegMask &out_RegMask() const;
225   virtual const RegMask &in_RegMask(uint) const;
226 #ifndef PRODUCT
227   virtual void dump_spec(outputStream *st) const;
228 #endif
229 #ifdef ASSERT
230   void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
231   void verify_adr_type(bool recursive = false) const;
232 #else //ASSERT
233   void verify_adr_type(bool recursive = false) const {}
234 #endif //ASSERT
235 };
236 
237 //------------------------------GotoNode---------------------------------------
238 // GotoNodes perform direct branches.
239 class GotoNode : public Node {
240 public:
241   GotoNode( Node *control ) : Node(control) {}
242   virtual int Opcode() const;
243   virtual bool pinned() const { return true; }
244   virtual bool  is_CFG() const { return true; }
245   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
246   virtual const Node *is_block_proj() const { return this; }
247   virtual bool depends_only_on_test() const { return false; }
248   virtual const Type *bottom_type() const { return Type::CONTROL; }
249   virtual const Type* Value(PhaseGVN* phase) const;
250   virtual Node* Identity(PhaseGVN* phase);
251   virtual const RegMask &out_RegMask() const;
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, bool fold_ne = false);
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* search_identical(int dist);
307 
308   Node* simple_subsuming(PhaseIterGVN* igvn);
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   Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
396 
397   // Takes the type of val and filters it through the test represented
398   // by if_proj and returns a more refined type if one is produced.
399   // Returns NULL is it couldn't improve the type.
400   static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
401 
402 #ifndef PRODUCT
403   virtual void dump_spec(outputStream *st) 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 
431 class IfTrueNode : public IfProjNode {
432 public:
433   IfTrueNode( IfNode *ifnode ) : IfProjNode(ifnode,1) {
434     init_class_id(Class_IfTrue);
435   }
436   virtual int Opcode() const;
437 
438 protected:
439   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFTRUE; }
440 };
441 
442 class IfFalseNode : public IfProjNode {
443 public:
444   IfFalseNode( IfNode *ifnode ) : IfProjNode(ifnode,0) {
445     init_class_id(Class_IfFalse);
446   }
447   virtual int Opcode() const;
448 
449 protected:
450   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFFALSE; }
451 };
452 
453 
454 //------------------------------PCTableNode------------------------------------
455 // Build an indirect branch table.  Given a control and a table index,
456 // control is passed to the Projection matching the table index.  Used to
457 // implement switch statements and exception-handling capabilities.
458 // Undefined behavior if passed-in index is not inside the table.
459 class PCTableNode : public MultiBranchNode {
460   virtual uint hash() const;    // Target count; table size
461   virtual bool cmp( const Node &n ) const;
462   virtual uint size_of() const { return sizeof(*this); }
463 
464 public:
465   const uint _size;             // Number of targets
466 
467   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
468     init_class_id(Class_PCTable);
469     init_req(0, ctrl);
470     init_req(1, idx);
471   }
472   virtual int Opcode() const;
473   virtual const Type* Value(PhaseGVN* phase) const;
474   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
475   virtual const Type *bottom_type() const;
476   virtual bool pinned() const { return true; }
477   virtual int required_outcnt() const { return _size; }
478 };
479 
480 //------------------------------JumpNode---------------------------------------
481 // Indirect branch.  Uses PCTable above to implement a switch statement.
482 // It emits as a table load and local branch.
483 class JumpNode : public PCTableNode {
484   virtual uint size_of() const { return sizeof(*this); }
485 public:
486   float* _probs; // probability of each projection
487   float _fcnt;   // total number of times this Jump was executed
488   JumpNode( Node* control, Node* switch_val, uint size, float* probs, float cnt)
489     : PCTableNode(control, switch_val, size),
490       _probs(probs), _fcnt(cnt) {
491     init_class_id(Class_Jump);
492   }
493   virtual int   Opcode() const;
494   virtual const RegMask& out_RegMask() const;
495   virtual const Node* is_block_proj() const { return this; }
496 };
497 
498 class JumpProjNode : public JProjNode {
499   virtual uint hash() const;
500   virtual bool cmp( const Node &n ) const;
501   virtual uint size_of() const { return sizeof(*this); }
502 
503  private:
504   const int  _dest_bci;
505   const uint _proj_no;
506   const int  _switch_val;
507  public:
508   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
509     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
510     init_class_id(Class_JumpProj);
511   }
512 
513   virtual int Opcode() const;
514   virtual const Type* bottom_type() const { return Type::CONTROL; }
515   int  dest_bci()    const { return _dest_bci; }
516   int  switch_val()  const { return _switch_val; }
517   uint proj_no()     const { return _proj_no; }
518 #ifndef PRODUCT
519   virtual void dump_spec(outputStream *st) const;
520   virtual void dump_compact_spec(outputStream *st) const;
521 #endif
522 };
523 
524 //------------------------------CatchNode--------------------------------------
525 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by
526 // a just-prior call.  Looks like a PCTableNode but emits no code - just the
527 // table.  The table lookup and branch is implemented by RethrowNode.
528 class CatchNode : public PCTableNode {
529 public:
530   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
531     init_class_id(Class_Catch);
532   }
533   virtual int Opcode() const;
534   virtual const Type* Value(PhaseGVN* phase) const;
535 };
536 
537 // CatchProjNode controls which exception handler is targeted after a call.
538 // It is passed in the bci of the target handler, or no_handler_bci in case
539 // the projection doesn't lead to an exception handler.
540 class CatchProjNode : public CProjNode {
541   virtual uint hash() const;
542   virtual bool cmp( const Node &n ) const;
543   virtual uint size_of() const { return sizeof(*this); }
544 
545 private:
546   const int _handler_bci;
547 
548 public:
549   enum {
550     fall_through_index =  0,      // the fall through projection index
551     catch_all_index    =  1,      // the projection index for catch-alls
552     no_handler_bci     = -1       // the bci for fall through or catch-all projs
553   };
554 
555   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
556     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
557     init_class_id(Class_CatchProj);
558     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
559   }
560 
561   virtual int Opcode() const;
562   virtual Node* Identity(PhaseGVN* phase);
563   virtual const Type *bottom_type() const { return Type::CONTROL; }
564   int  handler_bci() const        { return _handler_bci; }
565   bool is_handler_proj() const    { return _handler_bci >= 0; }
566 #ifndef PRODUCT
567   virtual void dump_spec(outputStream *st) const;
568 #endif
569 };
570 
571 
572 //---------------------------------CreateExNode--------------------------------
573 // Helper node to create the exception coming back from a call
574 class CreateExNode : public TypeNode {
575 public:
576   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
577     init_req(0, control);
578     init_req(1, i_o);
579   }
580   virtual int Opcode() const;
581   virtual Node* Identity(PhaseGVN* phase);
582   virtual bool pinned() const { return true; }
583   uint match_edge(uint idx) const { return 0; }
584   virtual uint ideal_reg() const { return Op_RegP; }
585 };
586 
587 //------------------------------NeverBranchNode-------------------------------
588 // The never-taken branch.  Used to give the appearance of exiting infinite
589 // loops to those algorithms that like all paths to be reachable.  Encodes
590 // empty.
591 class NeverBranchNode : public MultiBranchNode {
592 public:
593   NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
594   virtual int Opcode() const;
595   virtual bool pinned() const { return true; };
596   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
597   virtual const Type* Value(PhaseGVN* phase) const;
598   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
599   virtual int required_outcnt() const { return 2; }
600   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
601   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
602 #ifndef PRODUCT
603   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
604 #endif
605 };
606 
607 #endif // SHARE_OPTO_CFGNODE_HPP