1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  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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 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
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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     BlackholeNode;
 51 class   ProjNode;
 52 class     CProjNode;
 53 class       IfTrueNode;
 54 class       IfFalseNode;
 55 class       CatchProjNode;
 56 class     JProjNode;
 57 class       JumpProjNode;
 58 class     SCMemProjNode;
 59 class PhaseIdealLoop;
 60 enum class AssertionPredicateType;
 61 
 62 // The success projection of a Parse Predicate is always an IfTrueNode and the uncommon projection an IfFalseNode
 63 typedef IfTrueNode ParsePredicateSuccessProj;
 64 typedef IfFalseNode ParsePredicateUncommonProj;
 65 
 66 //------------------------------RegionNode-------------------------------------
 67 // The class of RegionNodes, which can be mapped to basic blocks in the
 68 // program.  Their inputs point to Control sources.  PhiNodes (described
 69 // below) have an input point to a RegionNode.  Merged data inputs to PhiNodes
 70 // correspond 1-to-1 with RegionNode inputs.  The zero input of a PhiNode is
 71 // the RegionNode, and the zero input of the RegionNode is itself.
 72 class RegionNode : public Node {
 73 public:
 74   enum LoopStatus {
 75     // No guarantee: the region may be an irreducible loop entry, thus we have to
 76     // be careful when removing entry control to it.
 77     MaybeIrreducibleEntry,
 78     // Limited guarantee: this region may be (nested) inside an irreducible loop,
 79     // but it will never be an irreducible loop entry.
 80     NeverIrreducibleEntry,
 81     // Strong guarantee: this region is not (nested) inside an irreducible loop.
 82     Reducible,
 83   };
 84 
 85 private:
 86   bool _is_unreachable_region;
 87   LoopStatus _loop_status;
 88 
 89   bool is_possible_unsafe_loop(const PhaseGVN* phase) const;
 90   bool is_unreachable_from_root(const PhaseGVN* phase) const;
 91 public:
 92   // Node layout (parallels PhiNode):
 93   enum { Region,                // Generally points to self.
 94          Control                // Control arcs are [1..len)
 95   };
 96 
 97   RegionNode(uint required)
 98     : Node(required),
 99       _is_unreachable_region(false),
100       _loop_status(LoopStatus::NeverIrreducibleEntry)
101   {
102     init_class_id(Class_Region);
103     init_req(0, this);
104   }
105 
106   Node* is_copy() const {
107     const Node* r = _in[Region];
108     if (r == nullptr)
109       return nonnull_req();
110     return nullptr;  // not a copy!
111   }
112   PhiNode* has_phi() const;        // returns an arbitrary phi user, or null
113   PhiNode* has_unique_phi() const; // returns the unique phi user, or null
114   // Is this region node unreachable from root?
115   bool is_unreachable_region(const PhaseGVN* phase);
116 #ifdef ASSERT
117   bool is_in_infinite_subgraph();
118   static bool are_all_nodes_in_infinite_subgraph(Unique_Node_List& worklist);
119 #endif //ASSERT
120   LoopStatus loop_status() const { return _loop_status; };
121   void set_loop_status(LoopStatus status);
122   DEBUG_ONLY(void verify_can_be_irreducible_entry() const;)
123 
124   virtual int Opcode() const;
125   virtual uint size_of() const { return sizeof(*this); }
126   virtual bool pinned() const { return (const Node*)in(0) == this; }
127   virtual bool is_CFG() const { return true; }
128   virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
129   virtual bool depends_only_on_test() const { return false; }
130   virtual const Type* bottom_type() const { return Type::CONTROL; }
131   virtual const Type* Value(PhaseGVN* phase) const;
132   virtual Node* Identity(PhaseGVN* phase);
133   virtual Node* Ideal(PhaseGVN* phase, bool can_reshape);
134   void remove_unreachable_subgraph(PhaseIterGVN* igvn);
135   virtual const RegMask &out_RegMask() const;
136   bool is_diamond() const;
137   void try_clean_mem_phis(PhaseIterGVN* phase);
138   bool optimize_trichotomy(PhaseIterGVN* igvn);
139   NOT_PRODUCT(virtual void dump_spec(outputStream* st) const;)
140 };
141 
142 //------------------------------JProjNode--------------------------------------
143 // jump projection for node that produces multiple control-flow paths
144 class JProjNode : public ProjNode {
145  public:
146   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
147   virtual int Opcode() const;
148   virtual bool  is_CFG() const { return true; }
149   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash
150   virtual const Node* is_block_proj() const { return in(0); }
151   virtual const RegMask& out_RegMask() const;
152   virtual uint  ideal_reg() const { return 0; }
153 };
154 
155 //------------------------------PhiNode----------------------------------------
156 // PhiNodes merge values from different Control paths.  Slot 0 points to the
157 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow
158 // paths to the RegionNode.
159 class PhiNode : public TypeNode {
160   friend class PhaseRenumberLive;
161 
162   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
163   // The following fields are only used for data PhiNodes to indicate
164   // that the PhiNode represents the value of a known instance field.
165         int _inst_mem_id; // Instance memory id (node index of the memory Phi)
166         int _inst_id;     // Instance id of the memory slice.
167   const int _inst_index;  // Alias index of the instance memory slice.
168   // Array elements references have the same alias_idx but different offset.
169   const int _inst_offset; // Offset of the instance memory slice.
170   // Size is bigger to hold the _adr_type field.
171   virtual uint hash() const;    // Check the type
172   virtual bool cmp( const Node &n ) const;
173   virtual uint size_of() const { return sizeof(*this); }
174 
175   // Determine if CMoveNode::is_cmove_id can be used at this join point.
176   Node* is_cmove_id(PhaseTransform* phase, int true_path);
177   bool wait_for_region_igvn(PhaseGVN* phase);
178   bool is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase);
179 
180   static Node* clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn);
181   static Node* merge_through_phi(Node* root_phi, PhaseIterGVN* igvn);
182 
183   bool must_wait_for_region_in_irreducible_loop(PhaseGVN* phase) const;
184 
185   bool can_push_inline_types_down(PhaseGVN* phase, bool can_reshape, ciInlineKlass*& inline_klass);
186   InlineTypeNode* push_inline_types_down(PhaseGVN* phase, bool can_reshape, ciInlineKlass* inline_klass);
187 
188 public:
189   // Node layout (parallels RegionNode):
190   enum { Region,                // Control input is the Phi's region.
191          Input                  // Input values are [1..len)
192   };
193 
194   PhiNode( Node *r, const Type *t, const TypePtr* at = nullptr,
195            const int imid = -1,
196            const int iid = TypeOopPtr::InstanceTop,
197            const int iidx = Compile::AliasIdxTop,
198            const int ioffs = Type::OffsetTop )
199     : TypeNode(t,r->req()),
200       _adr_type(at),
201       _inst_mem_id(imid),
202       _inst_id(iid),
203       _inst_index(iidx),
204       _inst_offset(ioffs)
205   {
206     init_class_id(Class_Phi);
207     init_req(0, r);
208     verify_adr_type();
209   }
210   // create a new phi with in edges matching r and set (initially) to x
211   static PhiNode* make( Node* r, Node* x );
212   // extra type arguments override the new phi's bottom_type and adr_type
213   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = nullptr );
214   // create a new phi with narrowed memory type
215   PhiNode* slice_memory(const TypePtr* adr_type) const;
216   PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
217   // like make(r, x), but does not initialize the in edges to x
218   static PhiNode* make_blank( Node* r, Node* x );
219 
220   // Accessors
221   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
222 
223   bool is_tripcount(BasicType bt) const;
224 
225   // Determine a unique non-trivial input, if any.
226   // Ignore casts if it helps.  Return null on failure.
227   Node* unique_input(PhaseValues* phase, bool uncast);
228   Node* unique_input(PhaseValues* phase) {
229     Node* uin = unique_input(phase, false);
230     if (uin == nullptr) {
231       uin = unique_input(phase, true);
232     }
233     return uin;
234   }
235 
236   // Check for a simple dead loop.
237   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
238   LoopSafety simple_data_loop_check(Node *in) const;
239   // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
240   bool is_unsafe_data_reference(Node *in) const;
241   int is_diamond_phi() const;
242   bool try_clean_memory_phi(PhaseIterGVN* igvn);
243   virtual int Opcode() const;
244   virtual bool pinned() const { return in(0) != nullptr; }
245   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
246 
247   void  set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
248   int inst_mem_id() const { return _inst_mem_id; }
249   int inst_id()     const { return _inst_id; }
250   int inst_index()  const { return _inst_index; }
251   int inst_offset() const { return _inst_offset; }
252   bool is_same_inst_field(const Type* tp, int mem_id, int id, int index, int offset) {
253     return type()->basic_type() == tp->basic_type() &&
254            inst_mem_id() == mem_id &&
255            inst_id()     == id     &&
256            inst_index()  == index  &&
257            inst_offset() == offset &&
258            type()->higher_equal(tp);
259   }
260 
261   bool can_be_inline_type() const {
262     return EnableValhalla && _type->isa_instptr() && _type->is_instptr()->can_be_inline_type();
263   }
264 
265   Node* try_push_inline_types_down(PhaseGVN* phase, bool can_reshape);
266   DEBUG_ONLY(bool can_push_inline_types_down(PhaseGVN* phase);)
267 
268   virtual const Type* Value(PhaseGVN* phase) const;
269   virtual Node* Identity(PhaseGVN* phase);
270   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
271   virtual const RegMask &out_RegMask() const;
272   virtual const RegMask &in_RegMask(uint) const;
273 #ifndef PRODUCT
274   virtual void dump_spec(outputStream *st) const;
275 #endif
276 #ifdef ASSERT
277   void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
278   void verify_adr_type(bool recursive = false) const;
279 #else //ASSERT
280   void verify_adr_type(bool recursive = false) const {}
281 #endif //ASSERT
282 
283   const TypeTuple* collect_types(PhaseGVN* phase) const;
284 };
285 
286 //------------------------------GotoNode---------------------------------------
287 // GotoNodes perform direct branches.
288 class GotoNode : public Node {
289 public:
290   GotoNode( Node *control ) : Node(control) {}
291   virtual int Opcode() const;
292   virtual bool pinned() const { return true; }
293   virtual bool  is_CFG() const { return true; }
294   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
295   virtual const Node *is_block_proj() const { return this; }
296   virtual bool depends_only_on_test() const { return false; }
297   virtual const Type *bottom_type() const { return Type::CONTROL; }
298   virtual const Type* Value(PhaseGVN* phase) const;
299   virtual Node* Identity(PhaseGVN* phase);
300   virtual const RegMask &out_RegMask() const;
301 };
302 
303 //------------------------------CProjNode--------------------------------------
304 // control projection for node that produces multiple control-flow paths
305 class CProjNode : public ProjNode {
306 public:
307   CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
308   virtual int Opcode() const;
309   virtual bool  is_CFG() const { return true; }
310   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
311   virtual const Node *is_block_proj() const { return in(0); }
312   virtual const RegMask &out_RegMask() const;
313   virtual uint ideal_reg() const { return 0; }
314 };
315 
316 //---------------------------MultiBranchNode-----------------------------------
317 // This class defines a MultiBranchNode, a MultiNode which yields multiple
318 // control values. These are distinguished from other types of MultiNodes
319 // which yield multiple values, but control is always and only projection #0.
320 class MultiBranchNode : public MultiNode {
321 public:
322   MultiBranchNode( uint required ) : MultiNode(required) {
323     init_class_id(Class_MultiBranch);
324   }
325   // returns required number of users to be well formed.
326   virtual int required_outcnt() const = 0;
327 };
328 
329 //------------------------------IfNode-----------------------------------------
330 // Output selected Control, based on a boolean test
331 class IfNode : public MultiBranchNode {
332  public:
333   float _prob;                           // Probability of true path being taken.
334   float _fcnt;                           // Frequency counter
335 
336  private:
337   AssertionPredicateType _assertion_predicate_type;
338 
339   void init_node(Node* control, Node* bol) {
340     init_class_id(Class_If);
341     init_req(0, control);
342     init_req(1, bol);
343   }
344 
345   // Size is bigger to hold the probability field.  However, _prob does not
346   // change the semantics so it does not appear in the hash & cmp functions.
347   virtual uint size_of() const { return sizeof(*this); }
348 
349   // Helper methods for fold_compares
350   bool cmpi_folds(PhaseIterGVN* igvn, bool fold_ne = false);
351   bool is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn);
352   bool has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail);
353   bool has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn);
354   Node* merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
355   static void improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn);
356   bool is_cmp_with_loadrange(ProjNode* proj);
357   bool is_null_check(ProjNode* proj, PhaseIterGVN* igvn);
358   bool is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn);
359   void reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn);
360   bool fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn);
361   static bool is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc);
362 
363 protected:
364   ProjNode* range_check_trap_proj(int& flip, Node*& l, Node*& r);
365   Node* Ideal_common(PhaseGVN *phase, bool can_reshape);
366   Node* search_identical(int dist, PhaseIterGVN* igvn);
367 
368   Node* simple_subsuming(PhaseIterGVN* igvn);
369 
370 public:
371 
372   // Degrees of branch prediction probability by order of magnitude:
373   // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
374   // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
375 #define PROB_UNLIKELY_MAG(N)    (1e- ## N ## f)
376 #define PROB_LIKELY_MAG(N)      (1.0f-PROB_UNLIKELY_MAG(N))
377 
378   // Maximum and minimum branch prediction probabilties
379   // 1 in 1,000,000 (magnitude 6)
380   //
381   // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
382   // they are used to distinguish different situations:
383   //
384   // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
385   // very likely (unlikely) but with a concrete possibility of a rare
386   // contrary case.  These constants would be used for pinning
387   // measurements, and as measures for assertions that have high
388   // confidence, but some evidence of occasional failure.
389   //
390   // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
391   // there is no evidence at all that the contrary case has ever occurred.
392 
393 #define PROB_NEVER              PROB_UNLIKELY_MAG(6)
394 #define PROB_ALWAYS             PROB_LIKELY_MAG(6)
395 
396 #define PROB_MIN                PROB_UNLIKELY_MAG(6)
397 #define PROB_MAX                PROB_LIKELY_MAG(6)
398 
399   // Static branch prediction probabilities
400   // 1 in 10 (magnitude 1)
401 #define PROB_STATIC_INFREQUENT  PROB_UNLIKELY_MAG(1)
402 #define PROB_STATIC_FREQUENT    PROB_LIKELY_MAG(1)
403 
404   // Fair probability 50/50
405 #define PROB_FAIR               (0.5f)
406 
407   // Unknown probability sentinel
408 #define PROB_UNKNOWN            (-1.0f)
409 
410   // Probability "constructors", to distinguish as a probability any manifest
411   // constant without a names
412 #define PROB_LIKELY(x)          ((float) (x))
413 #define PROB_UNLIKELY(x)        (1.0f - (float)(x))
414 
415   // Other probabilities in use, but without a unique name, are documented
416   // here for lack of a better place:
417   //
418   // 1 in 1000 probabilities (magnitude 3):
419   //     threshold for converting to conditional move
420   //     likelihood of null check failure if a null HAS been seen before
421   //     likelihood of slow path taken in library calls
422   //
423   // 1 in 10,000 probabilities (magnitude 4):
424   //     threshold for making an uncommon trap probability more extreme
425   //     threshold for for making a null check implicit
426   //     likelihood of needing a gc if eden top moves during an allocation
427   //     likelihood of a predicted call failure
428   //
429   // 1 in 100,000 probabilities (magnitude 5):
430   //     threshold for ignoring counts when estimating path frequency
431   //     likelihood of FP clipping failure
432   //     likelihood of catching an exception from a try block
433   //     likelihood of null check failure if a null has NOT been seen before
434   //
435   // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
436   // gen_subtype_check() and catch_inline_exceptions().
437 
438   IfNode(Node* control, Node* bol, float p, float fcnt);
439   IfNode(Node* control, Node* bol, float p, float fcnt, AssertionPredicateType assertion_predicate_type);
440 
441   static IfNode* make_with_same_profile(IfNode* if_node_profile, Node* ctrl, BoolNode* bol);
442 
443   virtual int Opcode() const;
444   virtual bool pinned() const { return true; }
445   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
446   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
447   virtual const Type* Value(PhaseGVN* phase) const;
448   virtual int required_outcnt() const { return 2; }
449   virtual const RegMask &out_RegMask() const;
450   Node* fold_compares(PhaseIterGVN* phase);
451   static Node* up_one_dom(Node* curr, bool linear_only = false);
452   bool is_zero_trip_guard() const;
453   Node* dominated_by(Node* prev_dom, PhaseIterGVN* igvn, bool pin_array_access_nodes);
454   ProjNode* uncommon_trap_proj(CallStaticJavaNode*& call, Deoptimization::DeoptReason reason = Deoptimization::Reason_none) const;
455 
456   // Takes the type of val and filters it through the test represented
457   // by if_proj and returns a more refined type if one is produced.
458   // Returns null is it couldn't improve the type.
459   static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
460 
461   bool is_flat_array_check(PhaseTransform* phase, Node** array = nullptr);
462 
463   AssertionPredicateType assertion_predicate_type() const {
464     return _assertion_predicate_type;
465   }
466 
467 #ifndef PRODUCT
468   virtual void dump_spec(outputStream *st) const;
469 #endif
470 
471   bool same_condition(const Node* dom, PhaseIterGVN* igvn) const;
472 };
473 
474 class RangeCheckNode : public IfNode {
475 private:
476   int is_range_check(Node*& range, Node*& index, jint& offset);
477 
478 public:
479   RangeCheckNode(Node* control, Node* bol, float p, float fcnt) : IfNode(control, bol, p, fcnt) {
480     init_class_id(Class_RangeCheck);
481   }
482 
483   RangeCheckNode(Node* control, Node* bol, float p, float fcnt, AssertionPredicateType assertion_predicate_type)
484       : IfNode(control, bol, p, fcnt, assertion_predicate_type) {
485     init_class_id(Class_RangeCheck);
486   }
487 
488   virtual int Opcode() const;
489   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
490 };
491 
492 // Special node that denotes a Parse Predicate added during parsing. A Parse Predicate serves as placeholder to later
493 // create Regular Predicates (Runtime Predicates with possible Assertion Predicates) above it. Together they form a
494 // Predicate Block. The Parse Predicate and Regular Predicates share the same uncommon trap.
495 // There are three kinds of Parse Predicates:
496 // Loop Parse Predicate, Profiled Loop Parse Predicate (both used by Loop Predication), and Loop Limit Check Parse
497 // Predicate (used for integer overflow checks when creating a counted loop).
498 // More information about predicates can be found in loopPredicate.cpp.
499 class ParsePredicateNode : public IfNode {
500   Deoptimization::DeoptReason _deopt_reason;
501   bool _useless; // If the associated loop dies, this parse predicate becomes useless and can be cleaned up by Value().
502  public:
503   ParsePredicateNode(Node* control, Deoptimization::DeoptReason deopt_reason, PhaseGVN* gvn);
504   virtual int Opcode() const;
505   virtual uint size_of() const { return sizeof(*this); }
506 
507   Deoptimization::DeoptReason deopt_reason() const {
508     return _deopt_reason;
509   }
510 
511   bool is_useless() const {
512     return _useless;
513   }
514 
515   void mark_useless() {
516     _useless = true;
517   }
518 
519   void mark_useful() {
520     _useless = false;
521   }
522 
523   // Return the uncommon trap If projection of this Parse Predicate.
524   ParsePredicateUncommonProj* uncommon_proj() const {
525     return proj_out(0)->as_IfFalse();
526   }
527 
528   Node* uncommon_trap() const;
529 
530   Node* Ideal(PhaseGVN* phase, bool can_reshape) {
531     return nullptr; // Don't optimize
532   }
533 
534   const Type* Value(PhaseGVN* phase) const;
535   NOT_PRODUCT(void dump_spec(outputStream* st) const;)
536 };
537 
538 class IfProjNode : public CProjNode {
539 public:
540   IfProjNode(IfNode *ifnode, uint idx) : CProjNode(ifnode,idx) {}
541   virtual Node* Identity(PhaseGVN* phase);
542 
543   void pin_array_access_nodes(PhaseIterGVN* igvn);
544 
545 protected:
546   // Type of If input when this branch is always taken
547   virtual bool always_taken(const TypeTuple* t) const = 0;
548 };
549 
550 class IfTrueNode : public IfProjNode {
551 public:
552   IfTrueNode( IfNode *ifnode ) : IfProjNode(ifnode,1) {
553     init_class_id(Class_IfTrue);
554   }
555   virtual int Opcode() const;
556 
557 protected:
558   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFTRUE; }
559 };
560 
561 class IfFalseNode : public IfProjNode {
562 public:
563   IfFalseNode( IfNode *ifnode ) : IfProjNode(ifnode,0) {
564     init_class_id(Class_IfFalse);
565   }
566   virtual int Opcode() const;
567 
568 protected:
569   virtual bool always_taken(const TypeTuple* t) const { return t == TypeTuple::IFFALSE; }
570 };
571 
572 
573 //------------------------------PCTableNode------------------------------------
574 // Build an indirect branch table.  Given a control and a table index,
575 // control is passed to the Projection matching the table index.  Used to
576 // implement switch statements and exception-handling capabilities.
577 // Undefined behavior if passed-in index is not inside the table.
578 class PCTableNode : public MultiBranchNode {
579   virtual uint hash() const;    // Target count; table size
580   virtual bool cmp( const Node &n ) const;
581   virtual uint size_of() const { return sizeof(*this); }
582 
583 public:
584   const uint _size;             // Number of targets
585 
586   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
587     init_class_id(Class_PCTable);
588     init_req(0, ctrl);
589     init_req(1, idx);
590   }
591   virtual int Opcode() const;
592   virtual const Type* Value(PhaseGVN* phase) const;
593   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
594   virtual const Type *bottom_type() const;
595   virtual bool pinned() const { return true; }
596   virtual int required_outcnt() const { return _size; }
597 };
598 
599 //------------------------------JumpNode---------------------------------------
600 // Indirect branch.  Uses PCTable above to implement a switch statement.
601 // It emits as a table load and local branch.
602 class JumpNode : public PCTableNode {
603   virtual uint size_of() const { return sizeof(*this); }
604 public:
605   float* _probs; // probability of each projection
606   float _fcnt;   // total number of times this Jump was executed
607   JumpNode( Node* control, Node* switch_val, uint size, float* probs, float cnt)
608     : PCTableNode(control, switch_val, size),
609       _probs(probs), _fcnt(cnt) {
610     init_class_id(Class_Jump);
611   }
612   virtual int   Opcode() const;
613   virtual const RegMask& out_RegMask() const;
614   virtual const Node* is_block_proj() const { return this; }
615 };
616 
617 class JumpProjNode : public JProjNode {
618   virtual uint hash() const;
619   virtual bool cmp( const Node &n ) const;
620   virtual uint size_of() const { return sizeof(*this); }
621 
622  private:
623   const int  _dest_bci;
624   const uint _proj_no;
625   const int  _switch_val;
626  public:
627   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
628     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
629     init_class_id(Class_JumpProj);
630   }
631 
632   virtual int Opcode() const;
633   virtual const Type* bottom_type() const { return Type::CONTROL; }
634   int  dest_bci()    const { return _dest_bci; }
635   int  switch_val()  const { return _switch_val; }
636   uint proj_no()     const { return _proj_no; }
637 #ifndef PRODUCT
638   virtual void dump_spec(outputStream *st) const;
639   virtual void dump_compact_spec(outputStream *st) const;
640 #endif
641 };
642 
643 //------------------------------CatchNode--------------------------------------
644 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by
645 // a just-prior call.  Looks like a PCTableNode but emits no code - just the
646 // table.  The table lookup and branch is implemented by RethrowNode.
647 class CatchNode : public PCTableNode {
648 public:
649   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
650     init_class_id(Class_Catch);
651   }
652   virtual int Opcode() const;
653   virtual const Type* Value(PhaseGVN* phase) const;
654 };
655 
656 // CatchProjNode controls which exception handler is targeted after a call.
657 // It is passed in the bci of the target handler, or no_handler_bci in case
658 // the projection doesn't lead to an exception handler.
659 class CatchProjNode : public CProjNode {
660   virtual uint hash() const;
661   virtual bool cmp( const Node &n ) const;
662   virtual uint size_of() const { return sizeof(*this); }
663 
664 private:
665   const int _handler_bci;
666 
667 public:
668   enum {
669     fall_through_index =  0,      // the fall through projection index
670     catch_all_index    =  1,      // the projection index for catch-alls
671     no_handler_bci     = -1       // the bci for fall through or catch-all projs
672   };
673 
674   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
675     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
676     init_class_id(Class_CatchProj);
677     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
678   }
679 
680   virtual int Opcode() const;
681   virtual Node* Identity(PhaseGVN* phase);
682   virtual const Type *bottom_type() const { return Type::CONTROL; }
683   int  handler_bci() const        { return _handler_bci; }
684   bool is_handler_proj() const    { return _handler_bci >= 0; }
685 #ifndef PRODUCT
686   virtual void dump_spec(outputStream *st) const;
687 #endif
688 };
689 
690 
691 //---------------------------------CreateExNode--------------------------------
692 // Helper node to create the exception coming back from a call
693 class CreateExNode : public TypeNode {
694 public:
695   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
696     init_req(0, control);
697     init_req(1, i_o);
698   }
699   virtual int Opcode() const;
700   virtual Node* Identity(PhaseGVN* phase);
701   virtual bool pinned() const { return true; }
702   uint match_edge(uint idx) const { return 0; }
703   virtual uint ideal_reg() const { return Op_RegP; }
704 };
705 
706 //------------------------------NeverBranchNode-------------------------------
707 // The never-taken branch.  Used to give the appearance of exiting infinite
708 // loops to those algorithms that like all paths to be reachable.  Encodes
709 // empty.
710 class NeverBranchNode : public MultiBranchNode {
711 public:
712   NeverBranchNode(Node* ctrl) : MultiBranchNode(1) {
713     init_req(0, ctrl);
714     init_class_id(Class_NeverBranch);
715   }
716   virtual int Opcode() const;
717   virtual bool pinned() const { return true; };
718   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
719   virtual const Type* Value(PhaseGVN* phase) const;
720   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
721   virtual int required_outcnt() const { return 2; }
722   virtual void emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const { }
723   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
724 #ifndef PRODUCT
725   virtual void format( PhaseRegAlloc *, outputStream *st ) const;
726 #endif
727 };
728 
729 //------------------------------BlackholeNode----------------------------
730 // Blackhole all arguments. This node would survive through the compiler
731 // the effects on its arguments, and would be finally matched to nothing.
732 class BlackholeNode : public MultiNode {
733 public:
734   BlackholeNode(Node* ctrl) : MultiNode(1) {
735     init_req(TypeFunc::Control, ctrl);
736     init_class_id(Class_Blackhole);
737   }
738   virtual int   Opcode() const;
739   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
740   virtual const Type* bottom_type() const { return TypeTuple::MEMBAR; }
741 
742   const RegMask &in_RegMask(uint idx) const {
743     // Fake the incoming arguments mask for blackholes: accept all registers
744     // and all stack slots. This would avoid any redundant register moves
745     // for blackhole inputs.
746     return RegMask::All;
747   }
748 #ifndef PRODUCT
749   virtual void format(PhaseRegAlloc* ra, outputStream* st) const;
750 #endif
751 };
752 
753 
754 #endif // SHARE_OPTO_CFGNODE_HPP