src/share/vm/opto/cfgnode.hpp

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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 *
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 *
15 * You should have received a copy of the GNU General Public License version
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
21 * questions.
22 *
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 const int _inst_id; // Instance id of the memory slice.
123 const int _inst_index; // Alias index of the instance memory slice.
124 // Array elements references have the same alias_idx but different offset.
125 const int _inst_offset; // Offset of the instance memory slice.
126 // Size is bigger to hold the _adr_type field.
127 virtual uint hash() const; // Check the type
128 virtual uint cmp( const Node &n ) const;
129 virtual uint size_of() const { return sizeof(*this); }
130
131 // Determine if CMoveNode::is_cmove_id can be used at this join point.
132 Node* is_cmove_id(PhaseTransform* phase, int true_path);
133
134 public:
135 // Node layout (parallels RegionNode):
136 enum { Region, // Control input is the Phi's region.
137 Input // Input values are [1..len)
138 };
139
140 PhiNode( Node *r, const Type *t, const TypePtr* at = NULL,
141 const int iid = TypeOopPtr::InstanceTop,
142 const int iidx = Compile::AliasIdxTop,
143 const int ioffs = Type::OffsetTop )
144 : TypeNode(t,r->req()),
145 _adr_type(at),
146 _inst_id(iid),
147 _inst_index(iidx),
148 _inst_offset(ioffs)
149 {
150 init_class_id(Class_Phi);
151 init_req(0, r);
152 verify_adr_type();
153 }
154 // create a new phi with in edges matching r and set (initially) to x
155 static PhiNode* make( Node* r, Node* x );
156 // extra type arguments override the new phi's bottom_type and adr_type
157 static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );
158 // create a new phi with narrowed memory type
159 PhiNode* slice_memory(const TypePtr* adr_type) const;
160 PhiNode* split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const;
161 // like make(r, x), but does not initialize the in edges to x
162 static PhiNode* make_blank( Node* r, Node* x );
163
164 // Accessors
165 RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }
166
167 Node* is_copy() const {
168 // The node is a real phi if _in[0] is a Region node.
169 DEBUG_ONLY(const Node* r = _in[Region];)
170 assert(r != NULL && r->is_Region(), "Not valid control");
171 return NULL; // not a copy!
172 }
173
174 bool is_tripcount() const;
175
176 // Determine a unique non-trivial input, if any.
177 // Ignore casts if it helps. Return NULL on failure.
178 Node* unique_input(PhaseTransform *phase);
179
180 // Check for a simple dead loop.
181 enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
182 LoopSafety simple_data_loop_check(Node *in) const;
183 // Is it unsafe data loop? It becomes a dead loop if this phi node removed.
184 bool is_unsafe_data_reference(Node *in) const;
185 int is_diamond_phi(bool check_control_only = false) const;
186 virtual int Opcode() const;
187 virtual bool pinned() const { return in(0) != 0; }
188 virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
189
190 const int inst_id() const { return _inst_id; }
191 const int inst_index() const { return _inst_index; }
192 const int inst_offset() const { return _inst_offset; }
193 bool is_same_inst_field(const Type* tp, int id, int index, int offset) {
194 return type()->basic_type() == tp->basic_type() &&
195 inst_id() == id &&
196 inst_index() == index &&
197 inst_offset() == offset &&
198 type()->higher_equal(tp);
199 }
200
201 virtual const Type *Value( PhaseTransform *phase ) const;
202 virtual Node *Identity( PhaseTransform *phase );
203 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
204 virtual const RegMask &out_RegMask() const;
205 virtual const RegMask &in_RegMask(uint) const;
206 #ifndef PRODUCT
207 virtual void dump_spec(outputStream *st) const;
208 #endif
209 #ifdef ASSERT
210 void verify_adr_type(VectorSet& visited, const TypePtr* at) const;
211 void verify_adr_type(bool recursive = false) const;
212 #else //ASSERT
213 void verify_adr_type(bool recursive = false) const {}
214 #endif //ASSERT
215 };
216
217 //------------------------------GotoNode---------------------------------------
218 // GotoNodes perform direct branches.
219 class GotoNode : public Node {
220 public:
221 GotoNode( Node *control ) : Node(control) {}
222 virtual int Opcode() const;
223 virtual bool pinned() const { return true; }
224 virtual bool is_CFG() const { return true; }
225 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
226 virtual const Node *is_block_proj() const { return this; }
227 virtual bool depends_only_on_test() const { return false; }
228 virtual const Type *bottom_type() const { return Type::CONTROL; }
229 virtual const Type *Value( PhaseTransform *phase ) const;
230 virtual Node *Identity( PhaseTransform *phase );
231 virtual const RegMask &out_RegMask() const;
232 };
233
234 //------------------------------CProjNode--------------------------------------
235 // control projection for node that produces multiple control-flow paths
236 class CProjNode : public ProjNode {
237 public:
238 CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}
239 virtual int Opcode() const;
240 virtual bool is_CFG() const { return true; }
241 virtual uint hash() const { return NO_HASH; } // CFG nodes do not hash
242 virtual const Node *is_block_proj() const { return in(0); }
243 virtual const RegMask &out_RegMask() const;
244 virtual uint ideal_reg() const { return 0; }
245 };
246
247 //---------------------------MultiBranchNode-----------------------------------
248 // This class defines a MultiBranchNode, a MultiNode which yields multiple
249 // control values. These are distinguished from other types of MultiNodes
250 // which yield multiple values, but control is always and only projection #0.
251 class MultiBranchNode : public MultiNode {
252 public:
253 MultiBranchNode( uint required ) : MultiNode(required) {
254 init_class_id(Class_MultiBranch);
255 }
256 // returns required number of users to be well formed.
257 virtual int required_outcnt() const = 0;
258 };
259
260 //------------------------------IfNode-----------------------------------------
261 // Output selected Control, based on a boolean test
262 class IfNode : public MultiBranchNode {
263 // Size is bigger to hold the probability field. However, _prob does not
264 // change the semantics so it does not appear in the hash & cmp functions.
265 virtual uint size_of() const { return sizeof(*this); }
266 public:
267
268 // Degrees of branch prediction probability by order of magnitude:
269 // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.
270 // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)
271 #define PROB_UNLIKELY_MAG(N) (1e- ## N ## f)
272 #define PROB_LIKELY_MAG(N) (1.0f-PROB_UNLIKELY_MAG(N))
273
274 // Maximum and minimum branch prediction probabilties
275 // 1 in 1,000,000 (magnitude 6)
276 //
277 // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX
278 // they are used to distinguish different situations:
279 //
280 // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to
281 // very likely (unlikely) but with a concrete possibility of a rare
282 // contrary case. These constants would be used for pinning
283 // measurements, and as measures for assertions that have high
284 // confidence, but some evidence of occasional failure.
285 //
286 // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which
287 // there is no evidence at all that the contrary case has ever occurred.
288
289 #define PROB_NEVER PROB_UNLIKELY_MAG(6)
290 #define PROB_ALWAYS PROB_LIKELY_MAG(6)
291
292 #define PROB_MIN PROB_UNLIKELY_MAG(6)
293 #define PROB_MAX PROB_LIKELY_MAG(6)
294
295 // Static branch prediction probabilities
296 // 1 in 10 (magnitude 1)
297 #define PROB_STATIC_INFREQUENT PROB_UNLIKELY_MAG(1)
298 #define PROB_STATIC_FREQUENT PROB_LIKELY_MAG(1)
299
300 // Fair probability 50/50
301 #define PROB_FAIR (0.5f)
302
303 // Unknown probability sentinel
304 #define PROB_UNKNOWN (-1.0f)
305
306 // Probability "constructors", to distinguish as a probability any manifest
307 // constant without a names
308 #define PROB_LIKELY(x) ((float) (x))
309 #define PROB_UNLIKELY(x) (1.0f - (float)(x))
310
311 // Other probabilities in use, but without a unique name, are documented
312 // here for lack of a better place:
313 //
314 // 1 in 1000 probabilities (magnitude 3):
315 // threshold for converting to conditional move
316 // likelihood of null check failure if a null HAS been seen before
317 // likelihood of slow path taken in library calls
318 //
319 // 1 in 10,000 probabilities (magnitude 4):
320 // threshold for making an uncommon trap probability more extreme
321 // threshold for for making a null check implicit
322 // likelihood of needing a gc if eden top moves during an allocation
323 // likelihood of a predicted call failure
324 //
325 // 1 in 100,000 probabilities (magnitude 5):
326 // threshold for ignoring counts when estimating path frequency
327 // likelihood of FP clipping failure
328 // likelihood of catching an exception from a try block
329 // likelihood of null check failure if a null has NOT been seen before
330 //
331 // Magic manifest probabilities such as 0.83, 0.7, ... can be found in
332 // gen_subtype_check() and catch_inline_exceptions().
333
334 float _prob; // Probability of true path being taken.
335 float _fcnt; // Frequency counter
336 IfNode( Node *control, Node *b, float p, float fcnt )
337 : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {
338 init_class_id(Class_If);
339 init_req(0,control);
340 init_req(1,b);
341 }
342 virtual int Opcode() const;
343 virtual bool pinned() const { return true; }
344 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
345 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
346 virtual const Type *Value( PhaseTransform *phase ) const;
347 virtual int required_outcnt() const { return 2; }
348 virtual const RegMask &out_RegMask() const;
349 void dominated_by(Node* prev_dom, PhaseIterGVN* igvn);
350 int is_range_check(Node* &range, Node* &index, jint &offset);
351 Node* fold_compares(PhaseGVN* phase);
352 static Node* up_one_dom(Node* curr, bool linear_only = false);
353
354 // Takes the type of val and filters it through the test represented
355 // by if_proj and returns a more refined type if one is produced.
356 // Returns NULL is it couldn't improve the type.
357 static const TypeInt* filtered_int_type(PhaseGVN* phase, Node* val, Node* if_proj);
358
359 #ifndef PRODUCT
360 virtual void dump_spec(outputStream *st) const;
361 #endif
362 };
363
364 class IfTrueNode : public CProjNode {
365 public:
366 IfTrueNode( IfNode *ifnode ) : CProjNode(ifnode,1) {
367 init_class_id(Class_IfTrue);
368 }
369 virtual int Opcode() const;
370 virtual Node *Identity( PhaseTransform *phase );
371 };
372
373 class IfFalseNode : public CProjNode {
374 public:
375 IfFalseNode( IfNode *ifnode ) : CProjNode(ifnode,0) {
376 init_class_id(Class_IfFalse);
377 }
378 virtual int Opcode() const;
379 virtual Node *Identity( PhaseTransform *phase );
380 };
381
382
383 //------------------------------PCTableNode------------------------------------
384 // Build an indirect branch table. Given a control and a table index,
385 // control is passed to the Projection matching the table index. Used to
386 // implement switch statements and exception-handling capabilities.
387 // Undefined behavior if passed-in index is not inside the table.
388 class PCTableNode : public MultiBranchNode {
389 virtual uint hash() const; // Target count; table size
390 virtual uint cmp( const Node &n ) const;
391 virtual uint size_of() const { return sizeof(*this); }
392
393 public:
394 const uint _size; // Number of targets
395
396 PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {
397 init_class_id(Class_PCTable);
398 init_req(0, ctrl);
399 init_req(1, idx);
400 }
401 virtual int Opcode() const;
402 virtual const Type *Value( PhaseTransform *phase ) const;
403 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
404 virtual const Type *bottom_type() const;
405 virtual bool pinned() const { return true; }
406 virtual int required_outcnt() const { return _size; }
407 };
408
409 //------------------------------JumpNode---------------------------------------
410 // Indirect branch. Uses PCTable above to implement a switch statement.
411 // It emits as a table load and local branch.
412 class JumpNode : public PCTableNode {
413 public:
414 JumpNode( Node* control, Node* switch_val, uint size) : PCTableNode(control, switch_val, size) {
415 init_class_id(Class_Jump);
416 }
417 virtual int Opcode() const;
418 virtual const RegMask& out_RegMask() const;
419 virtual const Node* is_block_proj() const { return this; }
420 };
421
422 class JumpProjNode : public JProjNode {
423 virtual uint hash() const;
424 virtual uint cmp( const Node &n ) const;
425 virtual uint size_of() const { return sizeof(*this); }
426
427 private:
428 const int _dest_bci;
429 const uint _proj_no;
430 const int _switch_val;
431 public:
432 JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)
433 : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {
434 init_class_id(Class_JumpProj);
435 }
436
437 virtual int Opcode() const;
438 virtual const Type* bottom_type() const { return Type::CONTROL; }
439 int dest_bci() const { return _dest_bci; }
440 int switch_val() const { return _switch_val; }
441 uint proj_no() const { return _proj_no; }
442 #ifndef PRODUCT
443 virtual void dump_spec(outputStream *st) const;
444 #endif
445 };
446
447 //------------------------------CatchNode--------------------------------------
448 // Helper node to fork exceptions. "Catch" catches any exceptions thrown by
449 // a just-prior call. Looks like a PCTableNode but emits no code - just the
450 // table. The table lookup and branch is implemented by RethrowNode.
451 class CatchNode : public PCTableNode {
452 public:
453 CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){
454 init_class_id(Class_Catch);
455 }
456 virtual int Opcode() const;
457 virtual const Type *Value( PhaseTransform *phase ) const;
458 };
459
460 // CatchProjNode controls which exception handler is targetted after a call.
461 // It is passed in the bci of the target handler, or no_handler_bci in case
462 // the projection doesn't lead to an exception handler.
463 class CatchProjNode : public CProjNode {
464 virtual uint hash() const;
465 virtual uint cmp( const Node &n ) const;
466 virtual uint size_of() const { return sizeof(*this); }
467
468 private:
469 const int _handler_bci;
470
471 public:
472 enum {
473 fall_through_index = 0, // the fall through projection index
474 catch_all_index = 1, // the projection index for catch-alls
475 no_handler_bci = -1 // the bci for fall through or catch-all projs
476 };
477
478 CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)
479 : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {
480 init_class_id(Class_CatchProj);
481 assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");
482 }
483
484 virtual int Opcode() const;
485 virtual Node *Identity( PhaseTransform *phase );
486 virtual const Type *bottom_type() const { return Type::CONTROL; }
487 int handler_bci() const { return _handler_bci; }
488 bool is_handler_proj() const { return _handler_bci >= 0; }
489 #ifndef PRODUCT
490 virtual void dump_spec(outputStream *st) const;
491 #endif
492 };
493
494
495 //---------------------------------CreateExNode--------------------------------
496 // Helper node to create the exception coming back from a call
497 class CreateExNode : public TypeNode {
498 public:
499 CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {
500 init_req(0, control);
501 init_req(1, i_o);
502 }
503 virtual int Opcode() const;
504 virtual Node *Identity( PhaseTransform *phase );
505 virtual bool pinned() const { return true; }
506 uint match_edge(uint idx) const { return 0; }
507 virtual uint ideal_reg() const { return Op_RegP; }
508 };
509
510 //------------------------------NeverBranchNode-------------------------------
511 // The never-taken branch. Used to give the appearance of exiting infinite
512 // loops to those algorithms that like all paths to be reachable. Encodes
513 // empty.
514 class NeverBranchNode : public MultiBranchNode {
515 public:
516 NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }
517 virtual int Opcode() const;
518 virtual bool pinned() const { return true; };
519 virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }
520 virtual const Type *Value( PhaseTransform *phase ) const;
521 virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
522 virtual int required_outcnt() const { return 2; }
523 virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }
524 virtual uint size(PhaseRegAlloc *ra_) const { return 0; }
525 #ifndef PRODUCT
526 virtual void format( PhaseRegAlloc *, outputStream *st ) const;
527 #endif
528 };
529
530 #endif // SHARE_VM_OPTO_CFGNODE_HPP

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