1 /*
   2  * Copyright (c) 2007, 2013, 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.
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  23 
  24 #ifndef SHARE_VM_OPTO_SUPERWORD_HPP
  25 #define SHARE_VM_OPTO_SUPERWORD_HPP
  26 
  27 #include "opto/connode.hpp"
  28 #include "opto/loopnode.hpp"
  29 #include "opto/node.hpp"
  30 #include "opto/phaseX.hpp"
  31 #include "opto/vectornode.hpp"
  32 #include "utilities/growableArray.hpp"
  33 
  34 //
  35 //                  S U P E R W O R D   T R A N S F O R M
  36 //
  37 // SuperWords are short, fixed length vectors.
  38 //
  39 // Algorithm from:
  40 //
  41 // Exploiting SuperWord Level Parallelism with
  42 //   Multimedia Instruction Sets
  43 // by
  44 //   Samuel Larsen and Saman Amarasinghe
  45 //   MIT Laboratory for Computer Science
  46 // date
  47 //   May 2000
  48 // published in
  49 //   ACM SIGPLAN Notices
  50 //   Proceedings of ACM PLDI '00,  Volume 35 Issue 5
  51 //
  52 // Definition 3.1 A Pack is an n-tuple, <s1, ...,sn>, where
  53 // s1,...,sn are independent isomorphic statements in a basic
  54 // block.
  55 //
  56 // Definition 3.2 A PackSet is a set of Packs.
  57 //
  58 // Definition 3.3 A Pair is a Pack of size two, where the
  59 // first statement is considered the left element, and the
  60 // second statement is considered the right element.
  61 
  62 class SWPointer;
  63 class OrderedPair;
  64 
  65 // ========================= Dependence Graph =====================
  66 
  67 class DepMem;
  68 
  69 //------------------------------DepEdge---------------------------
  70 // An edge in the dependence graph.  The edges incident to a dependence
  71 // node are threaded through _next_in for incoming edges and _next_out
  72 // for outgoing edges.
  73 class DepEdge : public ResourceObj {
  74  protected:
  75   DepMem* _pred;
  76   DepMem* _succ;
  77   DepEdge* _next_in;   // list of in edges, null terminated
  78   DepEdge* _next_out;  // list of out edges, null terminated
  79 
  80  public:
  81   DepEdge(DepMem* pred, DepMem* succ, DepEdge* next_in, DepEdge* next_out) :
  82     _pred(pred), _succ(succ), _next_in(next_in), _next_out(next_out) {}
  83 
  84   DepEdge* next_in()  { return _next_in; }
  85   DepEdge* next_out() { return _next_out; }
  86   DepMem*  pred()     { return _pred; }
  87   DepMem*  succ()     { return _succ; }
  88 
  89   void print();
  90 };
  91 
  92 //------------------------------DepMem---------------------------
  93 // A node in the dependence graph.  _in_head starts the threaded list of
  94 // incoming edges, and _out_head starts the list of outgoing edges.
  95 class DepMem : public ResourceObj {
  96  protected:
  97   Node*    _node;     // Corresponding ideal node
  98   DepEdge* _in_head;  // Head of list of in edges, null terminated
  99   DepEdge* _out_head; // Head of list of out edges, null terminated
 100 
 101  public:
 102   DepMem(Node* node) : _node(node), _in_head(NULL), _out_head(NULL) {}
 103 
 104   Node*    node()                { return _node;     }
 105   DepEdge* in_head()             { return _in_head;  }
 106   DepEdge* out_head()            { return _out_head; }
 107   void set_in_head(DepEdge* hd)  { _in_head = hd;    }
 108   void set_out_head(DepEdge* hd) { _out_head = hd;   }
 109 
 110   int in_cnt();  // Incoming edge count
 111   int out_cnt(); // Outgoing edge count
 112 
 113   void print();
 114 };
 115 
 116 //------------------------------DepGraph---------------------------
 117 class DepGraph VALUE_OBJ_CLASS_SPEC {
 118  protected:
 119   Arena* _arena;
 120   GrowableArray<DepMem*> _map;
 121   DepMem* _root;
 122   DepMem* _tail;
 123 
 124  public:
 125   DepGraph(Arena* a) : _arena(a), _map(a, 8,  0, NULL) {
 126     _root = new (_arena) DepMem(NULL);
 127     _tail = new (_arena) DepMem(NULL);
 128   }
 129 
 130   DepMem* root() { return _root; }
 131   DepMem* tail() { return _tail; }
 132 
 133   // Return dependence node corresponding to an ideal node
 134   DepMem* dep(Node* node) { return _map.at(node->_idx); }
 135 
 136   // Make a new dependence graph node for an ideal node.
 137   DepMem* make_node(Node* node);
 138 
 139   // Make a new dependence graph edge dprec->dsucc
 140   DepEdge* make_edge(DepMem* dpred, DepMem* dsucc);
 141 
 142   DepEdge* make_edge(Node* pred,   Node* succ)   { return make_edge(dep(pred), dep(succ)); }
 143   DepEdge* make_edge(DepMem* pred, Node* succ)   { return make_edge(pred,      dep(succ)); }
 144   DepEdge* make_edge(Node* pred,   DepMem* succ) { return make_edge(dep(pred), succ);      }
 145 
 146   void init() { _map.clear(); } // initialize
 147 
 148   void print(Node* n)   { dep(n)->print(); }
 149   void print(DepMem* d) { d->print(); }
 150 };
 151 
 152 //------------------------------DepPreds---------------------------
 153 // Iterator over predecessors in the dependence graph and
 154 // non-memory-graph inputs of ideal nodes.
 155 class DepPreds : public StackObj {
 156 private:
 157   Node*    _n;
 158   int      _next_idx, _end_idx;
 159   DepEdge* _dep_next;
 160   Node*    _current;
 161   bool     _done;
 162 
 163 public:
 164   DepPreds(Node* n, DepGraph& dg);
 165   Node* current() { return _current; }
 166   bool  done()    { return _done; }
 167   void  next();
 168 };
 169 
 170 //------------------------------DepSuccs---------------------------
 171 // Iterator over successors in the dependence graph and
 172 // non-memory-graph outputs of ideal nodes.
 173 class DepSuccs : public StackObj {
 174 private:
 175   Node*    _n;
 176   int      _next_idx, _end_idx;
 177   DepEdge* _dep_next;
 178   Node*    _current;
 179   bool     _done;
 180 
 181 public:
 182   DepSuccs(Node* n, DepGraph& dg);
 183   Node* current() { return _current; }
 184   bool  done()    { return _done; }
 185   void  next();
 186 };
 187 
 188 
 189 // ========================= SuperWord =====================
 190 
 191 // -----------------------------SWNodeInfo---------------------------------
 192 // Per node info needed by SuperWord
 193 class SWNodeInfo VALUE_OBJ_CLASS_SPEC {
 194  public:
 195   int         _alignment; // memory alignment for a node
 196   int         _depth;     // Max expression (DAG) depth from block start
 197   const Type* _velt_type; // vector element type
 198   Node_List*  _my_pack;   // pack containing this node
 199 
 200   SWNodeInfo() : _alignment(-1), _depth(0), _velt_type(NULL), _my_pack(NULL) {}
 201   static const SWNodeInfo initial;
 202 };
 203 
 204 // JVMCI: OrderedPair is moved up to deal with compilation issues on Windows
 205 //------------------------------OrderedPair---------------------------
 206 // Ordered pair of Node*.
 207 class OrderedPair VALUE_OBJ_CLASS_SPEC {
 208  protected:
 209   Node* _p1;
 210   Node* _p2;
 211  public:
 212   OrderedPair() : _p1(NULL), _p2(NULL) {}
 213   OrderedPair(Node* p1, Node* p2) {
 214     if (p1->_idx < p2->_idx) {
 215       _p1 = p1; _p2 = p2;
 216     } else {
 217       _p1 = p2; _p2 = p1;
 218     }
 219   }
 220 
 221   bool operator==(const OrderedPair &rhs) {
 222     return _p1 == rhs._p1 && _p2 == rhs._p2;
 223   }
 224   void print() { tty->print("  (%d, %d)", _p1->_idx, _p2->_idx); }
 225 
 226   static const OrderedPair initial;
 227 };
 228 
 229 // -----------------------------SuperWord---------------------------------
 230 // Transforms scalar operations into packed (superword) operations.
 231 class SuperWord : public ResourceObj {
 232  private:
 233   PhaseIdealLoop* _phase;
 234   Arena*          _arena;
 235   PhaseIterGVN   &_igvn;
 236 
 237   enum consts { top_align = -1, bottom_align = -666 };
 238 
 239   GrowableArray<Node_List*> _packset;    // Packs for the current block
 240 
 241   GrowableArray<int> _bb_idx;            // Map from Node _idx to index within block
 242 
 243   GrowableArray<Node*> _block;           // Nodes in current block
 244   GrowableArray<Node*> _data_entry;      // Nodes with all inputs from outside
 245   GrowableArray<Node*> _mem_slice_head;  // Memory slice head nodes
 246   GrowableArray<Node*> _mem_slice_tail;  // Memory slice tail nodes
 247 
 248   GrowableArray<SWNodeInfo> _node_info;  // Info needed per node
 249 
 250   MemNode* _align_to_ref;                // Memory reference that pre-loop will align to
 251 
 252   GrowableArray<OrderedPair> _disjoint_ptrs; // runtime disambiguated pointer pairs
 253 
 254   DepGraph _dg; // Dependence graph
 255 
 256   // Scratch pads
 257   VectorSet    _visited;       // Visited set
 258   VectorSet    _post_visited;  // Post-visited set
 259   Node_Stack   _n_idx_list;    // List of (node,index) pairs
 260   GrowableArray<Node*> _nlist; // List of nodes
 261   GrowableArray<Node*> _stk;   // Stack of nodes
 262 
 263  public:
 264   SuperWord(PhaseIdealLoop* phase);
 265 
 266   void transform_loop(IdealLoopTree* lpt);
 267 
 268   // Accessors for SWPointer
 269   PhaseIdealLoop* phase()          { return _phase; }
 270   IdealLoopTree* lpt()             { return _lpt; }
 271   PhiNode* iv()                    { return _iv; }
 272 
 273  private:
 274   IdealLoopTree* _lpt;             // Current loop tree node
 275   LoopNode*      _lp;              // Current LoopNode
 276   Node*          _bb;              // Current basic block
 277   PhiNode*       _iv;              // Induction var
 278 
 279   // Accessors
 280   Arena* arena()                   { return _arena; }
 281 
 282   Node* bb()                       { return _bb; }
 283   void  set_bb(Node* bb)           { _bb = bb; }
 284 
 285   void set_lpt(IdealLoopTree* lpt) { _lpt = lpt; }
 286 
 287   LoopNode* lp()                   { return _lp; }
 288   void      set_lp(LoopNode* lp)   { _lp = lp;
 289                                      _iv = lp->as_CountedLoop()->phi()->as_Phi(); }
 290   int      iv_stride()             { return lp()->as_CountedLoop()->stride_con(); }
 291 
 292   int vector_width(Node* n) {
 293     BasicType bt = velt_basic_type(n);
 294     return MIN2(ABS(iv_stride()), Matcher::max_vector_size(bt));
 295   }
 296   int vector_width_in_bytes(Node* n) {
 297     BasicType bt = velt_basic_type(n);
 298     return vector_width(n)*type2aelembytes(bt);
 299   }
 300   MemNode* align_to_ref()            { return _align_to_ref; }
 301   void  set_align_to_ref(MemNode* m) { _align_to_ref = m; }
 302 
 303   Node* ctrl(Node* n) const { return _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n; }
 304 
 305   // block accessors
 306   bool in_bb(Node* n)      { return n != NULL && n->outcnt() > 0 && ctrl(n) == _bb; }
 307   int  bb_idx(Node* n)     { assert(in_bb(n), "must be"); return _bb_idx.at(n->_idx); }
 308   void set_bb_idx(Node* n, int i) { _bb_idx.at_put_grow(n->_idx, i); }
 309 
 310   // visited set accessors
 311   void visited_clear()           { _visited.Clear(); }
 312   void visited_set(Node* n)      { return _visited.set(bb_idx(n)); }
 313   int visited_test(Node* n)      { return _visited.test(bb_idx(n)); }
 314   int visited_test_set(Node* n)  { return _visited.test_set(bb_idx(n)); }
 315   void post_visited_clear()      { _post_visited.Clear(); }
 316   void post_visited_set(Node* n) { return _post_visited.set(bb_idx(n)); }
 317   int post_visited_test(Node* n) { return _post_visited.test(bb_idx(n)); }
 318 
 319   // Ensure node_info contains element "i"
 320   void grow_node_info(int i) { if (i >= _node_info.length()) _node_info.at_put_grow(i, SWNodeInfo::initial); }
 321 
 322   // memory alignment for a node
 323   int alignment(Node* n)                     { return _node_info.adr_at(bb_idx(n))->_alignment; }
 324   void set_alignment(Node* n, int a)         { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_alignment = a; }
 325 
 326   // Max expression (DAG) depth from beginning of the block for each node
 327   int depth(Node* n)                         { return _node_info.adr_at(bb_idx(n))->_depth; }
 328   void set_depth(Node* n, int d)             { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_depth = d; }
 329 
 330   // vector element type
 331   const Type* velt_type(Node* n)             { return _node_info.adr_at(bb_idx(n))->_velt_type; }
 332   BasicType velt_basic_type(Node* n)         { return velt_type(n)->array_element_basic_type(); }
 333   void set_velt_type(Node* n, const Type* t) { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_velt_type = t; }
 334   bool same_velt_type(Node* n1, Node* n2);
 335 
 336   // my_pack
 337   Node_List* my_pack(Node* n)                { return !in_bb(n) ? NULL : _node_info.adr_at(bb_idx(n))->_my_pack; }
 338   void set_my_pack(Node* n, Node_List* p)    { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_my_pack = p; }
 339 
 340   // methods
 341 
 342   // Extract the superword level parallelism
 343   void SLP_extract();
 344   // Find the adjacent memory references and create pack pairs for them.
 345   void find_adjacent_refs();
 346   // Find a memory reference to align the loop induction variable to.
 347   MemNode* find_align_to_ref(Node_List &memops);
 348   // Calculate loop's iv adjustment for this memory ops.
 349   int get_iv_adjustment(MemNode* mem);
 350   // Can the preloop align the reference to position zero in the vector?
 351   bool ref_is_alignable(SWPointer& p);
 352   // Construct dependency graph.
 353   void dependence_graph();
 354   // Return a memory slice (node list) in predecessor order starting at "start"
 355   void mem_slice_preds(Node* start, Node* stop, GrowableArray<Node*> &preds);
 356   // Can s1 and s2 be in a pack with s1 immediately preceding s2 and  s1 aligned at "align"
 357   bool stmts_can_pack(Node* s1, Node* s2, int align);
 358   // Does s exist in a pack at position pos?
 359   bool exists_at(Node* s, uint pos);
 360   // Is s1 immediately before s2 in memory?
 361   bool are_adjacent_refs(Node* s1, Node* s2);
 362   // Are s1 and s2 similar?
 363   bool isomorphic(Node* s1, Node* s2);
 364   // Is there no data path from s1 to s2 or s2 to s1?
 365   bool independent(Node* s1, Node* s2);
 366   // Helper for independent
 367   bool independent_path(Node* shallow, Node* deep, uint dp=0);
 368   void set_alignment(Node* s1, Node* s2, int align);
 369   int data_size(Node* s);
 370   // Extend packset by following use->def and def->use links from pack members.
 371   void extend_packlist();
 372   // Extend the packset by visiting operand definitions of nodes in pack p
 373   bool follow_use_defs(Node_List* p);
 374   // Extend the packset by visiting uses of nodes in pack p
 375   bool follow_def_uses(Node_List* p);
 376   // Estimate the savings from executing s1 and s2 as a pack
 377   int est_savings(Node* s1, Node* s2);
 378   int adjacent_profit(Node* s1, Node* s2);
 379   int pack_cost(int ct);
 380   int unpack_cost(int ct);
 381   // Combine packs A and B with A.last == B.first into A.first..,A.last,B.second,..B.last
 382   void combine_packs();
 383   // Construct the map from nodes to packs.
 384   void construct_my_pack_map();
 385   // Remove packs that are not implemented or not profitable.
 386   void filter_packs();
 387   // Adjust the memory graph for the packed operations
 388   void schedule();
 389   // Remove "current" from its current position in the memory graph and insert
 390   // it after the appropriate insert points (lip or uip);
 391   void remove_and_insert(MemNode *current, MemNode *prev, MemNode *lip, Node *uip, Unique_Node_List &schd_before);
 392   // Within a store pack, schedule stores together by moving out the sandwiched memory ops according
 393   // to dependence info; and within a load pack, move loads down to the last executed load.
 394   void co_locate_pack(Node_List* p);
 395   // Convert packs into vector node operations
 396   void output();
 397   // Create a vector operand for the nodes in pack p for operand: in(opd_idx)
 398   Node* vector_opd(Node_List* p, int opd_idx);
 399   // Can code be generated for pack p?
 400   bool implemented(Node_List* p);
 401   // For pack p, are all operands and all uses (with in the block) vector?
 402   bool profitable(Node_List* p);
 403   // If a use of pack p is not a vector use, then replace the use with an extract operation.
 404   void insert_extracts(Node_List* p);
 405   // Is use->in(u_idx) a vector use?
 406   bool is_vector_use(Node* use, int u_idx);
 407   // Construct reverse postorder list of block members
 408   bool construct_bb();
 409   // Initialize per node info
 410   void initialize_bb();
 411   // Insert n into block after pos
 412   void bb_insert_after(Node* n, int pos);
 413   // Compute max depth for expressions from beginning of block
 414   void compute_max_depth();
 415   // Compute necessary vector element type for expressions
 416   void compute_vector_element_type();
 417   // Are s1 and s2 in a pack pair and ordered as s1,s2?
 418   bool in_packset(Node* s1, Node* s2);
 419   // Is s in pack p?
 420   Node_List* in_pack(Node* s, Node_List* p);
 421   // Remove the pack at position pos in the packset
 422   void remove_pack_at(int pos);
 423   // Return the node executed first in pack p.
 424   Node* executed_first(Node_List* p);
 425   // Return the node executed last in pack p.
 426   Node* executed_last(Node_List* p);
 427   static LoadNode::ControlDependency control_dependency(Node_List* p);
 428   // Alignment within a vector memory reference
 429   int memory_alignment(MemNode* s, int iv_adjust);
 430   // (Start, end] half-open range defining which operands are vector
 431   void vector_opd_range(Node* n, uint* start, uint* end);
 432   // Smallest type containing range of values
 433   const Type* container_type(Node* n);
 434   // Adjust pre-loop limit so that in main loop, a load/store reference
 435   // to align_to_ref will be a position zero in the vector.
 436   void align_initial_loop_index(MemNode* align_to_ref);
 437   // Find pre loop end from main loop.  Returns null if none.
 438   CountedLoopEndNode* get_pre_loop_end(CountedLoopNode *cl);
 439   // Is the use of d1 in u1 at the same operand position as d2 in u2?
 440   bool opnd_positions_match(Node* d1, Node* u1, Node* d2, Node* u2);
 441   void init();
 442 
 443   // print methods
 444   void print_packset();
 445   void print_pack(Node_List* p);
 446   void print_bb();
 447   void print_stmt(Node* s);
 448   char* blank(uint depth);
 449 };
 450 
 451 
 452 
 453 //------------------------------SWPointer---------------------------
 454 // Information about an address for dependence checking and vector alignment
 455 class SWPointer VALUE_OBJ_CLASS_SPEC {
 456  protected:
 457   MemNode*   _mem;     // My memory reference node
 458   SuperWord* _slp;     // SuperWord class
 459 
 460   Node* _base;         // NULL if unsafe nonheap reference
 461   Node* _adr;          // address pointer
 462   jint  _scale;        // multiplier for iv (in bytes), 0 if no loop iv
 463   jint  _offset;       // constant offset (in bytes)
 464   Node* _invar;        // invariant offset (in bytes), NULL if none
 465   bool  _negate_invar; // if true then use: (0 - _invar)
 466 
 467   PhaseIdealLoop* phase() { return _slp->phase(); }
 468   IdealLoopTree*  lpt()   { return _slp->lpt(); }
 469   PhiNode*        iv()    { return _slp->iv();  } // Induction var
 470 
 471   bool invariant(Node* n) {
 472     Node *n_c = phase()->get_ctrl(n);
 473     return !lpt()->is_member(phase()->get_loop(n_c));
 474   }
 475 
 476   // Match: k*iv + offset
 477   bool scaled_iv_plus_offset(Node* n);
 478   // Match: k*iv where k is a constant that's not zero
 479   bool scaled_iv(Node* n);
 480   // Match: offset is (k [+/- invariant])
 481   bool offset_plus_k(Node* n, bool negate = false);
 482 
 483  public:
 484   enum CMP {
 485     Less          = 1,
 486     Greater       = 2,
 487     Equal         = 4,
 488     NotEqual      = (Less | Greater),
 489     NotComparable = (Less | Greater | Equal)
 490   };
 491 
 492   SWPointer(MemNode* mem, SuperWord* slp);
 493   // Following is used to create a temporary object during
 494   // the pattern match of an address expression.
 495   SWPointer(SWPointer* p);
 496 
 497   bool valid()  { return _adr != NULL; }
 498   bool has_iv() { return _scale != 0; }
 499 
 500   Node* base()            { return _base; }
 501   Node* adr()             { return _adr; }
 502   MemNode* mem()          { return _mem; }
 503   int   scale_in_bytes()  { return _scale; }
 504   Node* invar()           { return _invar; }
 505   bool  negate_invar()    { return _negate_invar; }
 506   int   offset_in_bytes() { return _offset; }
 507   int   memory_size()     { return _mem->memory_size(); }
 508 
 509   // Comparable?
 510   int cmp(SWPointer& q) {
 511     if (valid() && q.valid() &&
 512         (_adr == q._adr || _base == _adr && q._base == q._adr) &&
 513         _scale == q._scale   &&
 514         _invar == q._invar   &&
 515         _negate_invar == q._negate_invar) {
 516       bool overlap = q._offset <   _offset +   memory_size() &&
 517                        _offset < q._offset + q.memory_size();
 518       return overlap ? Equal : (_offset < q._offset ? Less : Greater);
 519     } else {
 520       return NotComparable;
 521     }
 522   }
 523 
 524   bool not_equal(SWPointer& q)    { return not_equal(cmp(q)); }
 525   bool equal(SWPointer& q)        { return equal(cmp(q)); }
 526   bool comparable(SWPointer& q)   { return comparable(cmp(q)); }
 527   static bool not_equal(int cmp)  { return cmp <= NotEqual; }
 528   static bool equal(int cmp)      { return cmp == Equal; }
 529   static bool comparable(int cmp) { return cmp < NotComparable; }
 530 
 531   void print();
 532 };
 533 
 534 #endif // SHARE_VM_OPTO_SUPERWORD_HPP