1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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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( PhaseTransform *phase ) const;
95 virtual Node *Identity( PhaseTransform *phase );
96 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
97 virtual const RegMask &out_RegMask() const;
98 };
99
100 //------------------------------JProjNode--------------------------------------
101 // jump projection for node that produces multiple control-flow paths
102 class JProjNode : public ProjNode {
103 public:
104 JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
105 virtual int Opcode() const;
106 virtual bool is_CFG() const { return true; }
107 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
108 virtual const Node* is_block_proj() const { return in(0); }
109 virtual const RegMask& out_RegMask() const;
110 virtual uint ideal_reg() const { return 0; }
111 };
112
113 //------------------------------PhiNode----------------------------------------
114 // PhiNodes merge values from different Control paths. Slot 0 points to the
115 // controlling RegionNode. Other slots map 1-for-1 with incoming control flow
116 // paths to the RegionNode. For speed reasons (to avoid another pass) we
117 // can turn PhiNodes into copys in-place by NULL'ing out their RegionNode
118 // input in slot 0.
119 class PhiNode : public TypeNode {
120 const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
121 const int _inst_id; // Instance id of the memory slice.
122 const int _inst_index; // Alias index of the instance memory slice.
123 // Array elements references have the same alias_idx but different offset.
124 const int _inst_offset; // Offset of the instance memory slice.
125 // Size is bigger to hold the _adr_type field.
126 virtual uint hash() const; // Check the type
127 virtual uint cmp( const Node &n ) const;
128 virtual uint size_of() const { return sizeof(*this); }
129
130 // Determine if CMoveNode::is_cmove_id can be used at this join point.
131 Node* is_cmove_id(PhaseTransform* phase, int true_path);
132
133 public:
134 // Node layout (parallels RegionNode):
135 enum { Region, // Control input is the Phi's region.
136 Input // Input values are [1..len)
137 };
138
139 PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
140 const int iid = TypeOopPtr::InstanceTop,
141 const int iidx = Compile::AliasIdxTop,
142 const int ioffs = Type::OffsetTop )
143 : TypeNode(t,r->req()),
144 _adr_type(at),
145 _inst_id(iid),
146 _inst_index(iidx),
147 _inst_offset(ioffs)
148 {
149 init_class_id(Class_Phi);
150 init_req(0, r);
151 verify_adr_type();
152 }
153 // create a new phi with in edges matching r and set (initially) to x
154 static PhiNode* make( Node* r, Node* x );
155 // extra type arguments override the new phi's bottom_type and adr_type
156 static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
157 // create a new phi with narrowed memory type
158 PhiNode* slice_memory(const TypePtr* adr_type) const;
159 PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
160 // like make(r, x), but does not initialize the in edges to x
161 static PhiNode* make_blank( Node* r, Node* x );
162
163 // Accessors
164 RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
165
166 Node* is_copy() const {
167 // The node is a real phi if _in[0] is a Region node.
168 DEBUG_ONLY(const Node* r = _in[Region];)
169 assert(r != NULL && r->is_Region(), "Not valid control");
170 return NULL; // not a copy!
171 }
172
173 bool is_tripcount() const;
174
175 // Determine a unique non-trivial input, if any.
176 // Ignore casts if it helps. Return NULL on failure.
177 Node* unique_input(PhaseTransform *phase);
178
179 // Check for a simple dead loop.
180 enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
181 LoopSafety simple_data_loop_check(Node *in) const;
182 // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
183 bool is_unsafe_data_reference(Node *in) const;
184 int is_diamond_phi() const;
185 virtual int Opcode() const;
186 virtual bool pinned() const { return in(0) != 0; }
187 virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
188
189 const int inst_id() const { return _inst_id; }
190 const int inst_index() const { return _inst_index; }
191 const int inst_offset() const { return _inst_offset; }
192 bool is_same_inst_field(const Type* tp, int id, int index, int offset) {
193 return type()->basic_type() == tp->basic_type() &&
194 inst_id() == id &&
195 inst_index() == index &&
196 inst_offset() == offset &&
197 type()->higher_equal(tp);
198 }
199
200 virtual const Type *Value( PhaseTransform *phase ) const;
201 virtual Node *Identity( PhaseTransform *phase );
202 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
203 virtual const RegMask &out_RegMask() const;
204 virtual const RegMask &in_RegMask(uint) const;
205 #ifndef PRODUCT
206 virtual void dump_spec(outputStream *st) const;
207 #endif
208 #ifdef ASSERT
209 void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
210 void verify_adr_type(bool recursive = false) const;
211 #else //ASSERT
212 void verify_adr_type(bool recursive = false) const {}
213 #endif //ASSERT
214 };
215
216 //------------------------------GotoNode---------------------------------------
217 // GotoNodes perform direct branches.
218 class GotoNode : public Node {
219 public:
220 GotoNode( Node *control ) : Node(control) {
221 init_flags(Flag_is_Goto);
222 }
223 virtual int Opcode() const;
224 virtual bool pinned() const { return true; }
225 virtual bool is_CFG() const { return true; }
226 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
227 virtual const Node *is_block_proj() const { return this; }
228 virtual bool depends_only_on_test() const { return false; }
229 virtual const Type *bottom_type() const { return Type::CONTROL; }
230 virtual const Type *Value( PhaseTransform *phase ) const;
231 virtual Node *Identity( PhaseTransform *phase );
232 virtual const RegMask &out_RegMask() const;
233 };
234
235 //------------------------------CProjNode--------------------------------------
236 // control projection for node that produces multiple control-flow paths
237 class CProjNode : public ProjNode {
238 public:
239 CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
240 virtual int Opcode() const;
241 virtual bool is_CFG() const { return true; }
242 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
243 virtual const Node *is_block_proj() const { return in(0); }
244 virtual const RegMask &out_RegMask() const;
245 virtual uint ideal_reg() const { return 0; }
246 };
247
248 //---------------------------MultiBranchNode-----------------------------------
249 // This class defines a MultiBranchNode, a MultiNode which yields multiple
250 // control values. These are distinguished from other types of MultiNodes
251 // which yield multiple values, but control is always and only projection #0.
252 class MultiBranchNode : public MultiNode {
253 public:
254 MultiBranchNode( uint required ) : MultiNode(required) {
255 init_class_id(Class_MultiBranch);
256 }
257 // returns required number of users to be well formed.
258 virtual int required_outcnt() const = 0;
259 };
260
261 //------------------------------IfNode-----------------------------------------
262 // Output selected Control, based on a boolean test
263 class IfNode : public MultiBranchNode {
264 // Size is bigger to hold the probability field. However, _prob does not
265 // change the semantics so it does not appear in the hash & cmp functions.
266 virtual uint size_of() const { return sizeof(*this); }
267 public:
268
269 // Degrees of branch prediction probability by order of magnitude:
270 // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
271 // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
272 #define PROB_UNLIKELY_MAG(N) (1e- ## N ## f)
273 #define PROB_LIKELY_MAG(N) (1.0f-PROB_UNLIKELY_MAG(N))
274
275 // Maximum and minimum branch prediction probabilties
276 // 1 in 1,000,000 (magnitude 6)
277 //
278 // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
279 // they are used to distinguish different situations:
280 //
281 // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
282 // very likely (unlikely) but with a concrete possibility of a rare
283 // contrary case. These constants would be used for pinning
284 // measurements, and as measures for assertions that have high
285 // confidence, but some evidence of occasional failure.
286 //
287 // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
288 // there is no evidence at all that the contrary case has ever occurred.
289
290 #define PROB_NEVER PROB_UNLIKELY_MAG(6)
291 #define PROB_ALWAYS PROB_LIKELY_MAG(6)
292
293 #define PROB_MIN PROB_UNLIKELY_MAG(6)
294 #define PROB_MAX PROB_LIKELY_MAG(6)
295
296 // Static branch prediction probabilities
297 // 1 in 10 (magnitude 1)
298 #define PROB_STATIC_INFREQUENT PROB_UNLIKELY_MAG(1)
299 #define PROB_STATIC_FREQUENT PROB_LIKELY_MAG(1)
300
301 // Fair probability 50/50
302 #define PROB_FAIR (0.5f)
303
304 // Unknown probability sentinel
305 #define PROB_UNKNOWN (-1.0f)
306
307 // Probability "constructors", to distinguish as a probability any manifest
308 // constant without a names
309 #define PROB_LIKELY(x) ((float) (x))
310 #define PROB_UNLIKELY(x) (1.0f - (float)(x))
311
312 // Other probabilities in use, but without a unique name, are documented
313 // here for lack of a better place:
314 //
315 // 1 in 1000 probabilities (magnitude 3):
316 // threshold for converting to conditional move
317 // likelihood of null check failure if a null HAS been seen before
318 // likelihood of slow path taken in library calls
319 //
320 // 1 in 10,000 probabilities (magnitude 4):
321 // threshold for making an uncommon trap probability more extreme
322 // threshold for for making a null check implicit
323 // likelihood of needing a gc if eden top moves during an allocation
324 // likelihood of a predicted call failure
325 //
326 // 1 in 100,000 probabilities (magnitude 5):
327 // threshold for ignoring counts when estimating path frequency
328 // likelihood of FP clipping failure
329 // likelihood of catching an exception from a try block
330 // likelihood of null check failure if a null has NOT been seen before
331 //
332 // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
333 // gen_subtype_check() and catch_inline_exceptions().
334
335 float _prob; // Probability of true path being taken.
336 float _fcnt; // Frequency counter
337 IfNode( Node *control, Node *b, float p, float fcnt )
338 : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
339 init_class_id(Class_If);
340 init_req(0,control);
341 init_req(1,b);
342 }
343 virtual int Opcode() const;
344 virtual bool pinned() const { return true; }
345 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
346 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
347 virtual const Type *Value( PhaseTransform *phase ) const;
348 virtual int required_outcnt() const { return 2; }
349 virtual const RegMask &out_RegMask() const;
350 void dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
351 int is_range_check(Node* &range, Node* &index, jint &offset);
352 Node* fold_compares(PhaseGVN* phase);
353 static Node* up_one_dom(Node* curr, bool linear_only = false);
354
355 // Takes the type of val and filters it through the test represented
356 // by if_proj and returns a more refined type if one is produced.
357 // Returns NULL is it couldn't improve the type.
358 static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
359
360 #ifndef PRODUCT
361 virtual void dump_spec(outputStream *st) const;
362 #endif
363 };
364
365 class IfTrueNode : public CProjNode {
366 public:
367 IfTrueNode( IfNode *ifnode ) : CProjNode(ifnode,1) {
368 init_class_id(Class_IfTrue);
369 }
370 virtual int Opcode() const;
371 virtual Node *Identity( PhaseTransform *phase );
372 };
373
374 class IfFalseNode : public CProjNode {
375 public:
376 IfFalseNode( IfNode *ifnode ) : CProjNode(ifnode,0) {
377 init_class_id(Class_IfFalse);
378 }
379 virtual int Opcode() const;
380 virtual Node *Identity( PhaseTransform *phase );
381 };
382
383
384 //------------------------------PCTableNode------------------------------------
385 // Build an indirect branch table. Given a control and a table index,
386 // control is passed to the Projection matching the table index. Used to
387 // implement switch statements and exception-handling capabilities.
388 // Undefined behavior if passed-in index is not inside the table.
389 class PCTableNode : public MultiBranchNode {
390 virtual uint hash() const; // Target count; table size
391 virtual uint cmp( const Node &n ) const;
392 virtual uint size_of() const { return sizeof(*this); }
393
394 public:
395 const uint _size; // Number of targets
396
397 PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
398 init_class_id(Class_PCTable);
399 init_req(0, ctrl);
400 init_req(1, idx);
401 }
402 virtual int Opcode() const;
403 virtual const Type *Value( PhaseTransform *phase ) const;
404 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
405 virtual const Type *bottom_type() const;
406 virtual bool pinned() const { return true; }
407 virtual int required_outcnt() const { return _size; }
408 };
409
410 //------------------------------JumpNode---------------------------------------
411 // Indirect branch. Uses PCTable above to implement a switch statement.
412 // It emits as a table load and local branch.
413 class JumpNode : public PCTableNode {
414 public:
415 JumpNode( Node* control, Node* switch_val, uint size) : PCTableNode(control, switch_val, size) {
416 init_class_id(Class_Jump);
417 }
418 virtual int Opcode() const;
419 virtual const RegMask& out_RegMask() const;
420 virtual const Node* is_block_proj() const { return this; }
421 };
422
423 class JumpProjNode : public JProjNode {
424 virtual uint hash() const;
425 virtual uint cmp( const Node &n ) const;
426 virtual uint size_of() const { return sizeof(*this); }
427
428 private:
429 const int _dest_bci;
430 const uint _proj_no;
431 const int _switch_val;
432 public:
433 JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
434 : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
435 init_class_id(Class_JumpProj);
436 }
437
438 virtual int Opcode() const;
439 virtual const Type* bottom_type() const { return Type::CONTROL; }
440 int dest_bci() const { return _dest_bci; }
441 int switch_val() const { return _switch_val; }
442 uint proj_no() const { return _proj_no; }
443 #ifndef PRODUCT
444 virtual void dump_spec(outputStream *st) const;
445 #endif
446 };
447
448 //------------------------------CatchNode--------------------------------------
449 // Helper node to fork exceptions. "Catch" catches any exceptions thrown by
450 // a just-prior call. Looks like a PCTableNode but emits no code - just the
451 // table. The table lookup and branch is implemented by RethrowNode.
452 class CatchNode : public PCTableNode {
453 public:
454 CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
455 init_class_id(Class_Catch);
456 }
457 virtual int Opcode() const;
458 virtual const Type *Value( PhaseTransform *phase ) const;
459 };
460
461 // CatchProjNode controls which exception handler is targetted after a call.
462 // It is passed in the bci of the target handler, or no_handler_bci in case
463 // the projection doesn't lead to an exception handler.
464 class CatchProjNode : public CProjNode {
465 virtual uint hash() const;
466 virtual uint cmp( const Node &n ) const;
467 virtual uint size_of() const { return sizeof(*this); }
468
469 private:
470 const int _handler_bci;
471
472 public:
473 enum {
474 fall_through_index = 0, // the fall through projection index
475 catch_all_index = 1, // the projection index for catch-alls
476 no_handler_bci = -1 // the bci for fall through or catch-all projs
477 };
478
479 CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
480 : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
481 init_class_id(Class_CatchProj);
482 assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
483 }
484
485 virtual int Opcode() const;
486 virtual Node *Identity( PhaseTransform *phase );
487 virtual const Type *bottom_type() const { return Type::CONTROL; }
488 int handler_bci() const { return _handler_bci; }
489 bool is_handler_proj() const { return _handler_bci >= 0; }
490 #ifndef PRODUCT
491 virtual void dump_spec(outputStream *st) const;
492 #endif
493 };
494
495
496 //---------------------------------CreateExNode--------------------------------
497 // Helper node to create the exception coming back from a call
498 class CreateExNode : public TypeNode {
499 public:
500 CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
501 init_req(0, control);
502 init_req(1, i_o);
503 }
504 virtual int Opcode() const;
505 virtual Node *Identity( PhaseTransform *phase );
506 virtual bool pinned() const { return true; }
507 uint match_edge(uint idx) const { return 0; }
508 virtual uint ideal_reg() const { return Op_RegP; }
509 };
510
511 //------------------------------NeverBranchNode-------------------------------
512 // The never-taken branch. Used to give the appearance of exiting infinite
513 // loops to those algorithms that like all paths to be reachable. Encodes
514 // empty.
515 class NeverBranchNode : public MultiBranchNode {
516 public:
517 NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
518 virtual int Opcode() const;
519 virtual bool pinned() const { return true; };
520 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
521 virtual const Type *Value( PhaseTransform *phase ) const;
522 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
523 virtual int required_outcnt() const { return 2; }
524 virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
525 virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
526 #ifndef PRODUCT
527 virtual void format( PhaseRegAlloc *, outputStream *st ) const;
528 #endif
529 };
530
531 #endif // SHARE_VM_OPTO_CFGNODE_HPP