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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
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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).
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
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 bool try_clean_mem_phi(PhaseGVN *phase);
99 };
100
101 //------------------------------JProjNode--------------------------------------
102 // jump projection for node that produces multiple control-flow paths
103 class JProjNode : public ProjNode {
104 public:
105 JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}
106 virtual int Opcode() const;
107 virtual bool is_CFG() const { return true; }
108 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
109 virtual const Node* is_block_proj() const { return in(0); }
110 virtual const RegMask& out_RegMask() const;
111 virtual uint ideal_reg() const { return 0; }
112 };
113
114 //------------------------------PhiNode----------------------------------------
115 // PhiNodes merge values from different Control paths. Slot 0 points to the
116 // controlling RegionNode. Other slots map 1-for-1 with incoming control flow
117 // paths to the RegionNode. For speed reasons (to avoid another pass) we
118 // can turn PhiNodes into copys in-place by NULL'ing out their RegionNode
119 // input in slot 0.
120 class PhiNode : public TypeNode {
121 const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.
122 // The following fields are only used for data PhiNodes to indicate
123 // that the PhiNode represents the value of a known instance field.
124 int _inst_mem_id; // Instance memory id (node index of the memory Phi)
125 const int _inst_id; // Instance id of the memory slice.
126 const int _inst_index; // Alias index of the instance memory slice.
127 // Array elements references have the same alias_idx but different offset.
128 const int _inst_offset; // Offset of the instance memory slice.
129 // Size is bigger to hold the _adr_type field.
130 virtual uint hash() const; // Check the type
131 virtual uint cmp( const Node &n ) const;
132 virtual uint size_of() const { return sizeof(*this); }
133
134 // Determine if CMoveNode::is_cmove_id can be used at this join point.
135 Node* is_cmove_id(PhaseTransform* phase, int true_path);
136
137 public:
138 // Node layout (parallels RegionNode):
139 enum { Region, // Control input is the Phi's region.
140 Input // Input values are [1..len)
141 };
142
143 PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
144 const int imid = -1,
145 const int iid = TypeOopPtr::InstanceTop,
146 const int iidx = Compile::AliasIdxTop,
147 const int ioffs = Type::OffsetTop )
148 : TypeNode(t,r->req()),
149 _adr_type(at),
150 _inst_mem_id(imid),
151 _inst_id(iid),
152 _inst_index(iidx),
153 _inst_offset(ioffs)
154 {
155 init_class_id(Class_Phi);
156 init_req(0, r);
157 verify_adr_type();
158 }
159 // create a new phi with in edges matching r and set (initially) to x
160 static PhiNode* make( Node* r, Node* x );
161 // extra type arguments override the new phi's bottom_type and adr_type
162 static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
163 // create a new phi with narrowed memory type
164 PhiNode* slice_memory(const TypePtr* adr_type) const;
165 PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
166 // like make(r, x), but does not initialize the in edges to x
167 static PhiNode* make_blank( Node* r, Node* x );
168
169 // Accessors
170 RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
171
172 Node* is_copy() const {
173 // The node is a real phi if _in[0] is a Region node.
174 DEBUG_ONLY(const Node* r = _in[Region];)
175 assert(r != NULL && r->is_Region(), "Not valid control");
176 return NULL; // not a copy!
177 }
178
179 bool is_tripcount() const;
180
181 // Determine a unique non-trivial input, if any.
182 // Ignore casts if it helps. Return NULL on failure.
183 Node* unique_input(PhaseTransform *phase);
184
185 // Check for a simple dead loop.
186 enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
187 LoopSafety simple_data_loop_check(Node *in) const;
188 // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
189 bool is_unsafe_data_reference(Node *in) const;
190 int is_diamond_phi(bool check_control_only = false) const;
191 virtual int Opcode() const;
192 virtual bool pinned() const { return in(0) != 0; }
193 virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
194
195 void set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
196 const int inst_mem_id() const { return _inst_mem_id; }
197 const int inst_id() const { return _inst_id; }
198 const int inst_index() const { return _inst_index; }
199 const int inst_offset() const { return _inst_offset; }
200 bool is_same_inst_field(const Type* tp, int mem_id, int id, int index, int offset) {
201 return type()->basic_type() == tp->basic_type() &&
202 inst_mem_id() == mem_id &&
203 inst_id() == id &&
204 inst_index() == index &&
205 inst_offset() == offset &&
206 type()->higher_equal(tp);
207 }
208
209 virtual const Type *Value( PhaseTransform *phase ) const;
210 virtual Node *Identity( PhaseTransform *phase );
211 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
212 virtual const RegMask &out_RegMask() const;
213 virtual const RegMask &in_RegMask(uint) const;
214 #ifndef PRODUCT
215 virtual void dump_spec(outputStream *st) const;
216 #endif
217 #ifdef ASSERT
218 void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
219 void verify_adr_type(bool recursive = false) const;
220 #else //ASSERT
221 void verify_adr_type(bool recursive = false) const {}
222 #endif //ASSERT
223 };
224
225 //------------------------------GotoNode---------------------------------------
226 // GotoNodes perform direct branches.
227 class GotoNode : public Node {
228 public:
229 GotoNode( Node *control ) : Node(control) {}
230 virtual int Opcode() const;
231 virtual bool pinned() const { return true; }
232 virtual bool is_CFG() const { return true; }
233 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
234 virtual const Node *is_block_proj() const { return this; }
235 virtual bool depends_only_on_test() const { return false; }
236 virtual const Type *bottom_type() const { return Type::CONTROL; }
237 virtual const Type *Value( PhaseTransform *phase ) const;
238 virtual Node *Identity( PhaseTransform *phase );
239 virtual const RegMask &out_RegMask() const;
240 };
241
242 //------------------------------CProjNode--------------------------------------
243 // control projection for node that produces multiple control-flow paths
244 class CProjNode : public ProjNode {
245 public:
246 CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
247 virtual int Opcode() const;
248 virtual bool is_CFG() const { return true; }
249 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
250 virtual const Node *is_block_proj() const { return in(0); }
251 virtual const RegMask &out_RegMask() const;
252 virtual uint ideal_reg() const { return 0; }
253 };
254
255 //---------------------------MultiBranchNode-----------------------------------
256 // This class defines a MultiBranchNode, a MultiNode which yields multiple
257 // control values. These are distinguished from other types of MultiNodes
258 // which yield multiple values, but control is always and only projection #0.
259 class MultiBranchNode : public MultiNode {
260 public:
261 MultiBranchNode( uint required ) : MultiNode(required) {
262 init_class_id(Class_MultiBranch);
263 }
264 // returns required number of users to be well formed.
265 virtual int required_outcnt() const = 0;
266 };
267
268 //------------------------------IfNode-----------------------------------------
269 // Output selected Control, based on a boolean test
270 class IfNode : public MultiBranchNode {
271 // Size is bigger to hold the probability field. However, _prob does not
272 // change the semantics so it does not appear in the hash & cmp functions.
273 virtual uint size_of() const { return sizeof(*this); }
274 public:
275
276 // Degrees of branch prediction probability by order of magnitude:
277 // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
278 // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
279 #define PROB_UNLIKELY_MAG(N) (1e- ## N ## f)
280 #define PROB_LIKELY_MAG(N) (1.0f-PROB_UNLIKELY_MAG(N))
281
282 // Maximum and minimum branch prediction probabilties
283 // 1 in 1,000,000 (magnitude 6)
284 //
285 // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
286 // they are used to distinguish different situations:
287 //
288 // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
289 // very likely (unlikely) but with a concrete possibility of a rare
290 // contrary case. These constants would be used for pinning
291 // measurements, and as measures for assertions that have high
292 // confidence, but some evidence of occasional failure.
293 //
294 // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
295 // there is no evidence at all that the contrary case has ever occurred.
296
297 #define PROB_NEVER PROB_UNLIKELY_MAG(6)
298 #define PROB_ALWAYS PROB_LIKELY_MAG(6)
299
300 #define PROB_MIN PROB_UNLIKELY_MAG(6)
301 #define PROB_MAX PROB_LIKELY_MAG(6)
302
303 // Static branch prediction probabilities
304 // 1 in 10 (magnitude 1)
305 #define PROB_STATIC_INFREQUENT PROB_UNLIKELY_MAG(1)
306 #define PROB_STATIC_FREQUENT PROB_LIKELY_MAG(1)
307
308 // Fair probability 50/50
309 #define PROB_FAIR (0.5f)
310
311 // Unknown probability sentinel
312 #define PROB_UNKNOWN (-1.0f)
313
314 // Probability "constructors", to distinguish as a probability any manifest
315 // constant without a names
316 #define PROB_LIKELY(x) ((float) (x))
317 #define PROB_UNLIKELY(x) (1.0f - (float)(x))
318
319 // Other probabilities in use, but without a unique name, are documented
320 // here for lack of a better place:
321 //
322 // 1 in 1000 probabilities (magnitude 3):
323 // threshold for converting to conditional move
324 // likelihood of null check failure if a null HAS been seen before
325 // likelihood of slow path taken in library calls
326 //
327 // 1 in 10,000 probabilities (magnitude 4):
328 // threshold for making an uncommon trap probability more extreme
329 // threshold for for making a null check implicit
330 // likelihood of needing a gc if eden top moves during an allocation
331 // likelihood of a predicted call failure
332 //
333 // 1 in 100,000 probabilities (magnitude 5):
334 // threshold for ignoring counts when estimating path frequency
335 // likelihood of FP clipping failure
336 // likelihood of catching an exception from a try block
337 // likelihood of null check failure if a null has NOT been seen before
338 //
339 // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
340 // gen_subtype_check() and catch_inline_exceptions().
341
342 float _prob; // Probability of true path being taken.
343 float _fcnt; // Frequency counter
344 IfNode( Node *control, Node *b, float p, float fcnt )
345 : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
346 init_class_id(Class_If);
347 init_req(0,control);
348 init_req(1,b);
349 }
350 virtual int Opcode() const;
351 virtual bool pinned() const { return true; }
352 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
353 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
354 virtual const Type *Value( PhaseTransform *phase ) const;
355 virtual int required_outcnt() const { return 2; }
356 virtual const RegMask &out_RegMask() const;
357 void dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
358 int is_range_check(Node* &range, Node* &index, jint &offset);
359 Node* fold_compares(PhaseGVN* phase);
360 static Node* up_one_dom(Node* curr, bool linear_only = false);
361
362 // Takes the type of val and filters it through the test represented
363 // by if_proj and returns a more refined type if one is produced.
364 // Returns NULL is it couldn't improve the type.
365 static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
366
367 bool is_g1_marking_if(PhaseTransform *phase) const;
368 bool is_shenandoah_marking_if(PhaseTransform *phase) const;
369
370 #ifndef PRODUCT
371 virtual void dump_spec(outputStream *st) const;
372 #endif
373 };
374
375 class IfTrueNode : public CProjNode {
376 public:
377 IfTrueNode( IfNode *ifnode ) : CProjNode(ifnode,1) {
378 init_class_id(Class_IfTrue);
379 }
380 virtual int Opcode() const;
381 virtual Node *Identity( PhaseTransform *phase );
382 };
383
384 class IfFalseNode : public CProjNode {
385 public:
386 IfFalseNode( IfNode *ifnode ) : CProjNode(ifnode,0) {
387 init_class_id(Class_IfFalse);
388 }
389 virtual int Opcode() const;
390 virtual Node *Identity( PhaseTransform *phase );
391 };
392
393
394 //------------------------------PCTableNode------------------------------------
395 // Build an indirect branch table. Given a control and a table index,
396 // control is passed to the Projection matching the table index. Used to
397 // implement switch statements and exception-handling capabilities.
398 // Undefined behavior if passed-in index is not inside the table.
399 class PCTableNode : public MultiBranchNode {
400 virtual uint hash() const; // Target count; table size
401 virtual uint cmp( const Node &n ) const;
402 virtual uint size_of() const { return sizeof(*this); }
403
404 public:
405 const uint _size; // Number of targets
406
407 PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
408 init_class_id(Class_PCTable);
409 init_req(0, ctrl);
410 init_req(1, idx);
411 }
412 virtual int Opcode() const;
413 virtual const Type *Value( PhaseTransform *phase ) const;
414 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
415 virtual const Type *bottom_type() const;
416 virtual bool pinned() const { return true; }
417 virtual int required_outcnt() const { return _size; }
418 };
419
420 //------------------------------JumpNode---------------------------------------
421 // Indirect branch. Uses PCTable above to implement a switch statement.
422 // It emits as a table load and local branch.
423 class JumpNode : public PCTableNode {
424 public:
425 JumpNode( Node* control, Node* switch_val, uint size) : PCTableNode(control, switch_val, size) {
426 init_class_id(Class_Jump);
427 }
428 virtual int Opcode() const;
429 virtual const RegMask& out_RegMask() const;
430 virtual const Node* is_block_proj() const { return this; }
431 };
432
433 class JumpProjNode : public JProjNode {
434 virtual uint hash() const;
435 virtual uint cmp( const Node &n ) const;
436 virtual uint size_of() const { return sizeof(*this); }
437
438 private:
439 const int _dest_bci;
440 const uint _proj_no;
441 const int _switch_val;
442 public:
443 JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
444 : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
445 init_class_id(Class_JumpProj);
446 }
447
448 virtual int Opcode() const;
449 virtual const Type* bottom_type() const { return Type::CONTROL; }
450 int dest_bci() const { return _dest_bci; }
451 int switch_val() const { return _switch_val; }
452 uint proj_no() const { return _proj_no; }
453 #ifndef PRODUCT
454 virtual void dump_spec(outputStream *st) const;
455 #endif
456 };
457
458 //------------------------------CatchNode--------------------------------------
459 // Helper node to fork exceptions. "Catch" catches any exceptions thrown by
460 // a just-prior call. Looks like a PCTableNode but emits no code - just the
461 // table. The table lookup and branch is implemented by RethrowNode.
462 class CatchNode : public PCTableNode {
463 public:
464 CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
465 init_class_id(Class_Catch);
466 }
467 virtual int Opcode() const;
468 virtual const Type *Value( PhaseTransform *phase ) const;
469 };
470
471 // CatchProjNode controls which exception handler is targetted after a call.
472 // It is passed in the bci of the target handler, or no_handler_bci in case
473 // the projection doesn't lead to an exception handler.
474 class CatchProjNode : public CProjNode {
475 virtual uint hash() const;
476 virtual uint cmp( const Node &n ) const;
477 virtual uint size_of() const { return sizeof(*this); }
478
479 private:
480 const int _handler_bci;
481
482 public:
483 enum {
484 fall_through_index = 0, // the fall through projection index
485 catch_all_index = 1, // the projection index for catch-alls
486 no_handler_bci = -1 // the bci for fall through or catch-all projs
487 };
488
489 CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
490 : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
491 init_class_id(Class_CatchProj);
492 assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
493 }
494
495 virtual int Opcode() const;
496 virtual Node *Identity( PhaseTransform *phase );
497 virtual const Type *bottom_type() const { return Type::CONTROL; }
498 int handler_bci() const { return _handler_bci; }
499 bool is_handler_proj() const { return _handler_bci >= 0; }
500 #ifndef PRODUCT
501 virtual void dump_spec(outputStream *st) const;
502 #endif
503 };
504
505
506 //---------------------------------CreateExNode--------------------------------
507 // Helper node to create the exception coming back from a call
508 class CreateExNode : public TypeNode {
509 public:
510 CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
511 init_req(0, control);
512 init_req(1, i_o);
513 }
514 virtual int Opcode() const;
515 virtual Node *Identity( PhaseTransform *phase );
516 virtual bool pinned() const { return true; }
517 uint match_edge(uint idx) const { return 0; }
518 virtual uint ideal_reg() const { return Op_RegP; }
519 };
520
521 //------------------------------NeverBranchNode-------------------------------
522 // The never-taken branch. Used to give the appearance of exiting infinite
523 // loops to those algorithms that like all paths to be reachable. Encodes
524 // empty.
525 class NeverBranchNode : public MultiBranchNode {
526 public:
527 NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
528 virtual int Opcode() const;
529 virtual bool pinned() const { return true; };
530 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
531 virtual const Type *Value( PhaseTransform *phase ) const;
532 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
533 virtual int required_outcnt() const { return 2; }
534 virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
535 virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
536 #ifndef PRODUCT
537 virtual void format( PhaseRegAlloc *, outputStream *st ) const;
538 #endif
539 };
540
541 #endif // SHARE_VM_OPTO_CFGNODE_HPP