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 optimize_trichotomy(PhaseIterGVN* igvn);
105 };
106 
107 //------------------------------JProjNode--------------------------------------
108 // jump projection for node that produces multiple control-flow paths
109 class JProjNode : public ProjNode {
110  public:
111   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
112   virtual int Opcode() const;
113   virtual bool  is_CFG() const { return true; }
114   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash
115   virtual const Node* is_block_proj() const { return in(0); }
116   virtual const RegMask& out_RegMask() const;
117   virtual uint  ideal_reg() const { return 0; }
118 };
119 
120 //------------------------------PhiNode----------------------------------------
121 // PhiNodes merge values from different Control paths.  Slot 0 points to the
122 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow
123 // paths to the RegionNode.
124 class PhiNode : public TypeNode {
125   friend class PhaseRenumberLive;
126 
127   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
128   // The following fields are only used for data PhiNodes to indicate
129   // that the PhiNode represents the value of a known instance field.
130         int _inst_mem_id; // Instance memory id (node index of the memory Phi)
131         int _inst_id;     // Instance id of the memory slice.
132   const int _inst_index;  // Alias index of the instance memory slice.
133   // Array elements references have the same alias_idx but different offset.
134   const int _inst_offset; // Offset of the instance memory slice.
135   // Size is bigger to hold the _adr_type field.
136   virtual uint hash() const;    // Check the type
137   virtual bool cmp( const Node &n ) const;
138   virtual uint size_of() const { return sizeof(*this); }
139 
140   // Determine if CMoveNode::is_cmove_id can be used at this join point.
141   Node* is_cmove_id(PhaseTransform* phase, int true_path);
142   bool wait_for_region_igvn(PhaseGVN* phase);
143   bool is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase);
144 
145 public:
146   // Node layout (parallels RegionNode):
147   enum { Region,                // Control input is the Phi's region.
148          Input                  // Input values are [1..len)
149   };
150 
151   PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
152            const int imid = -1,
153            const int iid = TypeOopPtr::InstanceTop,
154            const int iidx = Compile::AliasIdxTop,
155            const int ioffs = Type::OffsetTop )
156     : TypeNode(t,r->req()),
157       _adr_type(at),
158       _inst_mem_id(imid),
159       _inst_id(iid),
160       _inst_index(iidx),
161       _inst_offset(ioffs)
162   {
163     init_class_id(Class_Phi);
164     init_req(0, r);
165     verify_adr_type();
166   }
167   // create a new phi with in edges matching r and set (initially) to x
168   static PhiNode* make( Node* r, Node* x );
169   // extra type arguments override the new phi's bottom_type and adr_type
170   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
171   // create a new phi with narrowed memory type
172   PhiNode* slice_memory(const TypePtr* adr_type) const;
173   PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
174   // like make(r, x), but does not initialize the in edges to x
175   static PhiNode* make_blank( Node* r, Node* x );
176 
177   // Accessors
178   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
179 
180   bool is_tripcount(BasicType bt) 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   Node* try_clean_mem_phi(PhaseGVN *phase);
217 
218   InlineTypeBaseNode* push_inline_types_through(PhaseGVN* phase, bool can_reshape, ciInlineKlass* vk, bool is_init);
219 
220   virtual const Type* Value(PhaseGVN* phase) const;
221   virtual Node* Identity(PhaseGVN* phase);
222   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
223   virtual const RegMask &out_RegMask() const;
224   virtual const RegMask &in_RegMask(uint) const;
225 #ifndef PRODUCT
226   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
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 #ifndef PRODUCT
254   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
255 #endif
256 };
257 
258 //------------------------------CProjNode--------------------------------------
259 // control projection for node that produces multiple control-flow paths
260 class CProjNode : public ProjNode {
261 public:
262   CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
263   virtual int Opcode() const;
264   virtual bool  is_CFG() const { return true; }
265   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
266   virtual const Node *is_block_proj() const { return in(0); }
267   virtual const RegMask &out_RegMask() const;
268   virtual uint ideal_reg() const { return 0; }
269 };
270 
271 //---------------------------MultiBranchNode-----------------------------------
272 // This class defines a MultiBranchNode, a MultiNode which yields multiple
273 // control values. These are distinguished from other types of MultiNodes
274 // which yield multiple values, but control is always and only projection #0.
275 class MultiBranchNode : public MultiNode {
276 public:
277   MultiBranchNode( uint required ) : MultiNode(required) {
278     init_class_id(Class_MultiBranch);
279   }
280   // returns required number of users to be well formed.
281   virtual int required_outcnt() const = 0;
282 };
283 
284 //------------------------------IfNode-----------------------------------------
285 // Output selected Control, based on a boolean test
286 class IfNode : public MultiBranchNode {
287   // Size is bigger to hold the probability field.  However, _prob does not
288   // change the semantics so it does not appear in the hash & cmp functions.
289   virtual uint size_of() const { return sizeof(*this); }
290 
291 private:
292   // Helper methods for fold_compares
293   bool cmpi_folds(PhaseIterGVN* igvn, bool fold_ne = false);
294   bool is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn);
295   bool has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail);
296   bool has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn);
297   Node* merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
298   static void improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn);
299   bool is_cmp_with_loadrange(ProjNode* proj);
300   bool is_null_check(ProjNode* proj, PhaseIterGVN* igvn);
301   bool is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn);
302   void reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn);
303   ProjNode* uncommon_trap_proj(CallStaticJavaNode*& call) const;
304   bool fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
305   static bool is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc);
306 
307 protected:
308   ProjNode* range_check_trap_proj(int& flip, Node*& l, Node*& r);
309   Node* Ideal_common(PhaseGVN *phase, bool can_reshape);
310   Node* search_identical(int dist);
311 
312   Node* simple_subsuming(PhaseIterGVN* igvn);
313 
314 public:
315 
316   // Degrees of branch prediction probability by order of magnitude:
317   // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
318   // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
319 #define PROB_UNLIKELY_MAG(N)    (1e- ## N ## f)
320 #define PROB_LIKELY_MAG(N)      (1.0f-PROB_UNLIKELY_MAG(N))
321 
322   // Maximum and minimum branch prediction probabilties
323   // 1 in 1,000,000 (magnitude 6)
324   //
325   // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
326   // they are used to distinguish different situations:
327   //
328   // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
329   // very likely (unlikely) but with a concrete possibility of a rare
330   // contrary case.  These constants would be used for pinning
331   // measurements, and as measures for assertions that have high
332   // confidence, but some evidence of occasional failure.
333   //
334   // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
335   // there is no evidence at all that the contrary case has ever occurred.
336 
337 #define PROB_NEVER              PROB_UNLIKELY_MAG(6)
338 #define PROB_ALWAYS             PROB_LIKELY_MAG(6)
339 
340 #define PROB_MIN                PROB_UNLIKELY_MAG(6)
341 #define PROB_MAX                PROB_LIKELY_MAG(6)
342 
343   // Static branch prediction probabilities
344   // 1 in 10 (magnitude 1)
345 #define PROB_STATIC_INFREQUENT  PROB_UNLIKELY_MAG(1)
346 #define PROB_STATIC_FREQUENT    PROB_LIKELY_MAG(1)
347 
348   // Fair probability 50/50
349 #define PROB_FAIR               (0.5f)
350 
351   // Unknown probability sentinel
352 #define PROB_UNKNOWN            (-1.0f)
353 
354   // Probability "constructors", to distinguish as a probability any manifest
355   // constant without a names
356 #define PROB_LIKELY(x)          ((float) (x))
357 #define PROB_UNLIKELY(x)        (1.0f - (float)(x))
358 
359   // Other probabilities in use, but without a unique name, are documented
360   // here for lack of a better place:
361   //
362   // 1 in 1000 probabilities (magnitude 3):
363   //     threshold for converting to conditional move
364   //     likelihood of null check failure if a null HAS been seen before
365   //     likelihood of slow path taken in library calls
366   //
367   // 1 in 10,000 probabilities (magnitude 4):
368   //     threshold for making an uncommon trap probability more extreme
369   //     threshold for for making a null check implicit
370   //     likelihood of needing a gc if eden top moves during an allocation
371   //     likelihood of a predicted call failure
372   //
373   // 1 in 100,000 probabilities (magnitude 5):
374   //     threshold for ignoring counts when estimating path frequency
375   //     likelihood of FP clipping failure
376   //     likelihood of catching an exception from a try block
377   //     likelihood of null check failure if a null has NOT been seen before
378   //
379   // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
380   // gen_subtype_check() and catch_inline_exceptions().
381 
382   float _prob;                  // Probability of true path being taken.
383   float _fcnt;                  // Frequency counter
384   IfNode( Node *control, Node *b, float p, float fcnt )
385     : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
386     init_class_id(Class_If);
387     init_req(0,control);
388     init_req(1,b);
389   }
390   virtual int Opcode() const;
391   virtual bool pinned() const { return true; }
392   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
393   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
394   virtual const Type* Value(PhaseGVN* phase) const;
395   virtual int required_outcnt() const { return 2; }
396   virtual const RegMask &out_RegMask() const;
397   Node* fold_compares(PhaseIterGVN* phase);
398   static Node* up_one_dom(Node* curr, bool linear_only = false);
399   Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
400 
401   // Takes the type of val and filters it through the test represented
402   // by if_proj and returns a more refined type if one is produced.
403   // Returns NULL is it couldn't improve the type.
404   static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
405 
406   bool is_flat_array_check(PhaseTransform* phase, Node** array = NULL);
407 
408 #ifndef PRODUCT
409   virtual void dump_spec(outputStream *st) const;
410   virtual void related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const;
411 #endif
412 };
413 
414 class RangeCheckNode : public IfNode {
415 private:
416   int is_range_check(Node* &range, Node* &index, jint &offset);
417 
418 public:
419   RangeCheckNode(Node* control, Node *b, float p, float fcnt)
420     : IfNode(control, b, p, fcnt) {
421     init_class_id(Class_RangeCheck);
422   }
423 
424   virtual int Opcode() const;
425   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
426 };
427 
428 class IfProjNode : public CProjNode {
429 public:
430   IfProjNode(IfNode *ifnode, uint idx) : CProjNode(ifnode,idx) {}
431   virtual Node* Identity(PhaseGVN* phase);
432 
433 protected:
434   // Type of If input when this branch is always taken
435   virtual bool always_taken(const TypeTuple* t) const = 0;
436 
437 #ifndef PRODUCT
438 public:
439   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
440 #endif
441 };
442 
443 class IfTrueNode : public IfProjNode {
444 public:
445   IfTrueNode( IfNode *ifnode ) : IfProjNode(ifnode,1) {
446     init_class_id(Class_IfTrue);
447   }
448   virtual int Opcode() const;
449 
450 protected:
451   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFTRUE; }
452 };
453 
454 class IfFalseNode : public IfProjNode {
455 public:
456   IfFalseNode( IfNode *ifnode ) : IfProjNode(ifnode,0) {
457     init_class_id(Class_IfFalse);
458   }
459   virtual int Opcode() const;
460 
461 protected:
462   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFFALSE; }
463 };
464 
465 
466 //------------------------------PCTableNode------------------------------------
467 // Build an indirect branch table.  Given a control and a table index,
468 // control is passed to the Projection matching the table index.  Used to
469 // implement switch statements and exception-handling capabilities.
470 // Undefined behavior if passed-in index is not inside the table.
471 class PCTableNode : public MultiBranchNode {
472   virtual uint hash() const;    // Target count; table size
473   virtual bool cmp( const Node &n ) const;
474   virtual uint size_of() const { return sizeof(*this); }
475 
476 public:
477   const uint _size;             // Number of targets
478 
479   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
480     init_class_id(Class_PCTable);
481     init_req(0, ctrl);
482     init_req(1, idx);
483   }
484   virtual int Opcode() const;
485   virtual const Type* Value(PhaseGVN* phase) const;
486   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
487   virtual const Type *bottom_type() const;
488   virtual bool pinned() const { return true; }
489   virtual int required_outcnt() const { return _size; }
490 };
491 
492 //------------------------------JumpNode---------------------------------------
493 // Indirect branch.  Uses PCTable above to implement a switch statement.
494 // It emits as a table load and local branch.
495 class JumpNode : public PCTableNode {
496   virtual uint size_of() const { return sizeof(*this); }
497 public:
498   float* _probs; // probability of each projection
499   float _fcnt;   // total number of times this Jump was executed
500   JumpNode( Node* control, Node* switch_val, uint size, float* probs, float cnt)
501     : PCTableNode(control, switch_val, size),
502       _probs(probs), _fcnt(cnt) {
503     init_class_id(Class_Jump);
504   }
505   virtual int   Opcode() const;
506   virtual const RegMask& out_RegMask() const;
507   virtual const Node* is_block_proj() const { return this; }
508 #ifndef PRODUCT
509   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
510 #endif
511 };
512 
513 class JumpProjNode : public JProjNode {
514   virtual uint hash() const;
515   virtual bool cmp( const Node &n ) const;
516   virtual uint size_of() const { return sizeof(*this); }
517 
518  private:
519   const int  _dest_bci;
520   const uint _proj_no;
521   const int  _switch_val;
522  public:
523   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
524     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
525     init_class_id(Class_JumpProj);
526   }
527 
528   virtual int Opcode() const;
529   virtual const Type* bottom_type() const { return Type::CONTROL; }
530   int  dest_bci()    const { return _dest_bci; }
531   int  switch_val()  const { return _switch_val; }
532   uint proj_no()     const { return _proj_no; }
533 #ifndef PRODUCT
534   virtual void dump_spec(outputStream *st) const;
535   virtual void dump_compact_spec(outputStream *st) const;
536   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
537 #endif
538 };
539 
540 //------------------------------CatchNode--------------------------------------
541 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by
542 // a just-prior call.  Looks like a PCTableNode but emits no code - just the
543 // table.  The table lookup and branch is implemented by RethrowNode.
544 class CatchNode : public PCTableNode {
545 public:
546   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
547     init_class_id(Class_Catch);
548   }
549   virtual int Opcode() const;
550   virtual const Type* Value(PhaseGVN* phase) const;
551 };
552 
553 // CatchProjNode controls which exception handler is targetted after a call.
554 // It is passed in the bci of the target handler, or no_handler_bci in case
555 // the projection doesn't lead to an exception handler.
556 class CatchProjNode : public CProjNode {
557   virtual uint hash() const;
558   virtual bool cmp( const Node &n ) const;
559   virtual uint size_of() const { return sizeof(*this); }
560 
561 private:
562   const int _handler_bci;
563 
564 public:
565   enum {
566     fall_through_index =  0,      // the fall through projection index
567     catch_all_index    =  1,      // the projection index for catch-alls
568     no_handler_bci     = -1       // the bci for fall through or catch-all projs
569   };
570 
571   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
572     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
573     init_class_id(Class_CatchProj);
574     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
575   }
576 
577   virtual int Opcode() const;
578   virtual Node* Identity(PhaseGVN* phase);
579   virtual const Type *bottom_type() const { return Type::CONTROL; }
580   int  handler_bci() const        { return _handler_bci; }
581   bool is_handler_proj() const    { return _handler_bci >= 0; }
582 #ifndef PRODUCT
583   virtual void dump_spec(outputStream *st) const;
584 #endif
585 };
586 
587 
588 //---------------------------------CreateExNode--------------------------------
589 // Helper node to create the exception coming back from a call
590 class CreateExNode : public TypeNode {
591 public:
592   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
593     init_req(0, control);
594     init_req(1, i_o);
595   }
596   virtual int Opcode() const;
597   virtual Node* Identity(PhaseGVN* phase);
598   virtual bool pinned() const { return true; }
599   uint match_edge(uint idx) const { return 0; }
600   virtual uint ideal_reg() const { return Op_RegP; }
601 };
602 
603 //------------------------------NeverBranchNode-------------------------------
604 // The never-taken branch.  Used to give the appearance of exiting infinite
605 // loops to those algorithms that like all paths to be reachable.  Encodes
606 // empty.
607 class NeverBranchNode : public MultiBranchNode {
608 public:
609   NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
610   virtual int Opcode() const;
611   virtual bool pinned() const { return true; };
612   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
613   virtual const Type* Value(PhaseGVN* phase) const;
614   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
615   virtual int required_outcnt() const { return 2; }
616   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
617   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
618 #ifndef PRODUCT
619   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
620 #endif
621 };
622 
623 #endif // SHARE_OPTO_CFGNODE_HPP