1 /*
   2  * Copyright (c) 2007, 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 #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 Amarasighe
  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 // -----------------------------SuperWord---------------------------------
 205 // Transforms scalar operations into packed (superword) operations.
 206 class SuperWord : public ResourceObj {
 207  private:
 208   PhaseIdealLoop* _phase;
 209   Arena*          _arena;
 210   PhaseIterGVN   &_igvn;
 211 
 212   enum consts { top_align = -1, bottom_align = -666 };
 213 
 214   GrowableArray<Node_List*> _packset;    // Packs for the current block
 215 
 216   GrowableArray<int> _bb_idx;            // Map from Node _idx to index within block
 217 
 218   GrowableArray<Node*> _block;           // Nodes in current block
 219   GrowableArray<Node*> _data_entry;      // Nodes with all inputs from outside
 220   GrowableArray<Node*> _mem_slice_head;  // Memory slice head nodes
 221   GrowableArray<Node*> _mem_slice_tail;  // Memory slice tail nodes
 222 
 223   GrowableArray<SWNodeInfo> _node_info;  // Info needed per node
 224 
 225   MemNode* _align_to_ref;                // Memory reference that pre-loop will align to
 226 
 227   GrowableArray<OrderedPair> _disjoint_ptrs; // runtime disambiguated pointer pairs
 228 
 229   DepGraph _dg; // Dependence graph
 230 
 231   // Scratch pads
 232   VectorSet    _visited;       // Visited set
 233   VectorSet    _post_visited;  // Post-visited set
 234   Node_Stack   _n_idx_list;    // List of (node,index) pairs
 235   GrowableArray<Node*> _nlist; // List of nodes
 236   GrowableArray<Node*> _stk;   // Stack of nodes
 237 
 238  public:
 239   SuperWord(PhaseIdealLoop* phase);
 240 
 241   void transform_loop(IdealLoopTree* lpt);
 242 
 243   // Accessors for SWPointer
 244   PhaseIdealLoop* phase()          { return _phase; }
 245   IdealLoopTree* lpt()             { return _lpt; }
 246   PhiNode* iv()                    { return _iv; }
 247 
 248  private:
 249   IdealLoopTree* _lpt;             // Current loop tree node
 250   LoopNode*      _lp;              // Current LoopNode
 251   Node*          _bb;              // Current basic block
 252   PhiNode*       _iv;              // Induction var
 253 
 254   // Accessors
 255   Arena* arena()                   { return _arena; }
 256 
 257   Node* bb()                       { return _bb; }
 258   void  set_bb(Node* bb)           { _bb = bb; }
 259 
 260   void set_lpt(IdealLoopTree* lpt) { _lpt = lpt; }
 261 
 262   LoopNode* lp()                   { return _lp; }
 263   void      set_lp(LoopNode* lp)   { _lp = lp;
 264                                      _iv = lp->as_CountedLoop()->phi()->as_Phi(); }
 265   int      iv_stride()             { return lp()->as_CountedLoop()->stride_con(); }
 266 
 267   int vector_width_in_bytes()      { return Matcher::vector_width_in_bytes(); }
 268 
 269   MemNode* align_to_ref()            { return _align_to_ref; }
 270   void  set_align_to_ref(MemNode* m) { _align_to_ref = m; }
 271 
 272   Node* ctrl(Node* n) const { return _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n; }
 273 
 274   // block accessors
 275   bool in_bb(Node* n)      { return n != NULL && n->outcnt() > 0 && ctrl(n) == _bb; }
 276   int  bb_idx(Node* n)     { assert(in_bb(n), "must be"); return _bb_idx.at(n->_idx); }
 277   void set_bb_idx(Node* n, int i) { _bb_idx.at_put_grow(n->_idx, i); }
 278 
 279   // visited set accessors
 280   void visited_clear()           { _visited.Clear(); }
 281   void visited_set(Node* n)      { return _visited.set(bb_idx(n)); }
 282   int visited_test(Node* n)      { return _visited.test(bb_idx(n)); }
 283   int visited_test_set(Node* n)  { return _visited.test_set(bb_idx(n)); }
 284   void post_visited_clear()      { _post_visited.Clear(); }
 285   void post_visited_set(Node* n) { return _post_visited.set(bb_idx(n)); }
 286   int post_visited_test(Node* n) { return _post_visited.test(bb_idx(n)); }
 287 
 288   // Ensure node_info contains element "i"
 289   void grow_node_info(int i) { if (i >= _node_info.length()) _node_info.at_put_grow(i, SWNodeInfo::initial); }
 290 
 291   // memory alignment for a node
 292   int alignment(Node* n)                     { return _node_info.adr_at(bb_idx(n))->_alignment; }
 293   void set_alignment(Node* n, int a)         { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_alignment = a; }
 294 
 295   // Max expression (DAG) depth from beginning of the block for each node
 296   int depth(Node* n)                         { return _node_info.adr_at(bb_idx(n))->_depth; }
 297   void set_depth(Node* n, int d)             { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_depth = d; }
 298 
 299   // vector element type
 300   const Type* velt_type(Node* n)             { return _node_info.adr_at(bb_idx(n))->_velt_type; }
 301   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; }
 302 
 303   // my_pack
 304   Node_List* my_pack(Node* n)                { return !in_bb(n) ? NULL : _node_info.adr_at(bb_idx(n))->_my_pack; }
 305   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; }
 306 
 307   // methods
 308 
 309   // Extract the superword level parallelism
 310   void SLP_extract();
 311   // Find the adjacent memory references and create pack pairs for them.
 312   void find_adjacent_refs();
 313   // Find a memory reference to align the loop induction variable to.
 314   void find_align_to_ref(Node_List &memops);
 315   // Can the preloop align the reference to position zero in the vector?
 316   bool ref_is_alignable(SWPointer& p);
 317   // Construct dependency graph.
 318   void dependence_graph();
 319   // Return a memory slice (node list) in predecessor order starting at "start"
 320   void mem_slice_preds(Node* start, Node* stop, GrowableArray<Node*> &preds);
 321   // Can s1 and s2 be in a pack with s1 immediately preceding s2 and  s1 aligned at "align"
 322   bool stmts_can_pack(Node* s1, Node* s2, int align);
 323   // Does s exist in a pack at position pos?
 324   bool exists_at(Node* s, uint pos);
 325   // Is s1 immediately before s2 in memory?
 326   bool are_adjacent_refs(Node* s1, Node* s2);
 327   // Are s1 and s2 similar?
 328   bool isomorphic(Node* s1, Node* s2);
 329   // Is there no data path from s1 to s2 or s2 to s1?
 330   bool independent(Node* s1, Node* s2);
 331   // Helper for independent
 332   bool independent_path(Node* shallow, Node* deep, uint dp=0);
 333   void set_alignment(Node* s1, Node* s2, int align);
 334   int data_size(Node* s);
 335   // Extend packset by following use->def and def->use links from pack members.
 336   void extend_packlist();
 337   // Extend the packset by visiting operand definitions of nodes in pack p
 338   bool follow_use_defs(Node_List* p);
 339   // Extend the packset by visiting uses of nodes in pack p
 340   bool follow_def_uses(Node_List* p);
 341   // Estimate the savings from executing s1 and s2 as a pack
 342   int est_savings(Node* s1, Node* s2);
 343   int adjacent_profit(Node* s1, Node* s2);
 344   int pack_cost(int ct);
 345   int unpack_cost(int ct);
 346   // Combine packs A and B with A.last == B.first into A.first..,A.last,B.second,..B.last
 347   void combine_packs();
 348   // Construct the map from nodes to packs.
 349   void construct_my_pack_map();
 350   // Remove packs that are not implemented or not profitable.
 351   void filter_packs();
 352   // Adjust the memory graph for the packed operations
 353   void schedule();
 354   // Remove "current" from its current position in the memory graph and insert
 355   // it after the appropriate insert points (lip or uip);
 356   void remove_and_insert(MemNode *current, MemNode *prev, MemNode *lip, Node *uip, Unique_Node_List &schd_before);
 357   // Within a store pack, schedule stores together by moving out the sandwiched memory ops according
 358   // to dependence info; and within a load pack, move loads down to the last executed load.
 359   void co_locate_pack(Node_List* p);
 360   // Convert packs into vector node operations
 361   void output();
 362   // Create a vector operand for the nodes in pack p for operand: in(opd_idx)
 363   VectorNode* vector_opd(Node_List* p, int opd_idx);
 364   // Can code be generated for pack p?
 365   bool implemented(Node_List* p);
 366   // For pack p, are all operands and all uses (with in the block) vector?
 367   bool profitable(Node_List* p);
 368   // If a use of pack p is not a vector use, then replace the use with an extract operation.
 369   void insert_extracts(Node_List* p);
 370   // Is use->in(u_idx) a vector use?
 371   bool is_vector_use(Node* use, int u_idx);
 372   // Construct reverse postorder list of block members
 373   void construct_bb();
 374   // Initialize per node info
 375   void initialize_bb();
 376   // Insert n into block after pos
 377   void bb_insert_after(Node* n, int pos);
 378   // Compute max depth for expressions from beginning of block
 379   void compute_max_depth();
 380   // Compute necessary vector element type for expressions
 381   void compute_vector_element_type();
 382   // Are s1 and s2 in a pack pair and ordered as s1,s2?
 383   bool in_packset(Node* s1, Node* s2);
 384   // Is s in pack p?
 385   Node_List* in_pack(Node* s, Node_List* p);
 386   // Remove the pack at position pos in the packset
 387   void remove_pack_at(int pos);
 388   // Return the node executed first in pack p.
 389   Node* executed_first(Node_List* p);
 390   // Return the node executed last in pack p.
 391   Node* executed_last(Node_List* p);
 392   // Alignment within a vector memory reference
 393   int memory_alignment(MemNode* s, int iv_adjust_in_bytes);
 394   // (Start, end] half-open range defining which operands are vector
 395   void vector_opd_range(Node* n, uint* start, uint* end);
 396   // Smallest type containing range of values
 397   static const Type* container_type(const Type* t);
 398   // Adjust pre-loop limit so that in main loop, a load/store reference
 399   // to align_to_ref will be a position zero in the vector.
 400   void align_initial_loop_index(MemNode* align_to_ref);
 401   // Find pre loop end from main loop.  Returns null if none.
 402   CountedLoopEndNode* get_pre_loop_end(CountedLoopNode *cl);
 403   // Is the use of d1 in u1 at the same operand position as d2 in u2?
 404   bool opnd_positions_match(Node* d1, Node* u1, Node* d2, Node* u2);
 405   void init();
 406 
 407   // print methods
 408   void print_packset();
 409   void print_pack(Node_List* p);
 410   void print_bb();
 411   void print_stmt(Node* s);
 412   char* blank(uint depth);
 413 };
 414 
 415 
 416 //------------------------------SWPointer---------------------------
 417 // Information about an address for dependence checking and vector alignment
 418 class SWPointer VALUE_OBJ_CLASS_SPEC {
 419  protected:
 420   MemNode*   _mem;     // My memory reference node
 421   SuperWord* _slp;     // SuperWord class
 422 
 423   Node* _base;         // NULL if unsafe nonheap reference
 424   Node* _adr;          // address pointer
 425   jint  _scale;        // multipler for iv (in bytes), 0 if no loop iv
 426   jint  _offset;       // constant offset (in bytes)
 427   Node* _invar;        // invariant offset (in bytes), NULL if none
 428   bool  _negate_invar; // if true then use: (0 - _invar)
 429 
 430   PhaseIdealLoop* phase() { return _slp->phase(); }
 431   IdealLoopTree*  lpt()   { return _slp->lpt(); }
 432   PhiNode*        iv()    { return _slp->iv();  } // Induction var
 433 
 434   bool invariant(Node* n) {
 435     Node *n_c = phase()->get_ctrl(n);
 436     return !lpt()->is_member(phase()->get_loop(n_c));
 437   }
 438 
 439   // Match: k*iv + offset
 440   bool scaled_iv_plus_offset(Node* n);
 441   // Match: k*iv where k is a constant that's not zero
 442   bool scaled_iv(Node* n);
 443   // Match: offset is (k [+/- invariant])
 444   bool offset_plus_k(Node* n, bool negate = false);
 445 
 446  public:
 447   enum CMP {
 448     Less          = 1,
 449     Greater       = 2,
 450     Equal         = 4,
 451     NotEqual      = (Less | Greater),
 452     NotComparable = (Less | Greater | Equal)
 453   };
 454 
 455   SWPointer(MemNode* mem, SuperWord* slp);
 456   // Following is used to create a temporary object during
 457   // the pattern match of an address expression.
 458   SWPointer(SWPointer* p);
 459 
 460   bool valid()  { return _adr != NULL; }
 461   bool has_iv() { return _scale != 0; }
 462 
 463   Node* base()            { return _base; }
 464   Node* adr()             { return _adr; }
 465   int   scale_in_bytes()  { return _scale; }
 466   Node* invar()           { return _invar; }
 467   bool  negate_invar()    { return _negate_invar; }
 468   int   offset_in_bytes() { return _offset; }
 469   int   memory_size()     { return _mem->memory_size(); }
 470 
 471   // Comparable?
 472   int cmp(SWPointer& q) {
 473     if (valid() && q.valid() &&
 474         (_adr == q._adr || _base == _adr && q._base == q._adr) &&
 475         _scale == q._scale   &&
 476         _invar == q._invar   &&
 477         _negate_invar == q._negate_invar) {
 478       bool overlap = q._offset <   _offset +   memory_size() &&
 479                        _offset < q._offset + q.memory_size();
 480       return overlap ? Equal : (_offset < q._offset ? Less : Greater);
 481     } else {
 482       return NotComparable;
 483     }
 484   }
 485 
 486   bool not_equal(SWPointer& q)    { return not_equal(cmp(q)); }
 487   bool equal(SWPointer& q)        { return equal(cmp(q)); }
 488   bool comparable(SWPointer& q)   { return comparable(cmp(q)); }
 489   static bool not_equal(int cmp)  { return cmp <= NotEqual; }
 490   static bool equal(int cmp)      { return cmp == Equal; }
 491   static bool comparable(int cmp) { return cmp < NotComparable; }
 492 
 493   void print();
 494 };
 495 
 496 
 497 //------------------------------OrderedPair---------------------------
 498 // Ordered pair of Node*.
 499 class OrderedPair VALUE_OBJ_CLASS_SPEC {
 500  protected:
 501   Node* _p1;
 502   Node* _p2;
 503  public:
 504   OrderedPair() : _p1(NULL), _p2(NULL) {}
 505   OrderedPair(Node* p1, Node* p2) {
 506     if (p1->_idx < p2->_idx) {
 507       _p1 = p1; _p2 = p2;
 508     } else {
 509       _p1 = p2; _p2 = p1;
 510     }
 511   }
 512 
 513   bool operator==(const OrderedPair &rhs) {
 514     return _p1 == rhs._p1 && _p2 == rhs._p2;
 515   }
 516   void print() { tty->print("  (%d, %d)", _p1->_idx, _p2->_idx); }
 517 
 518   static const OrderedPair initial;
 519 };
 520 
 521 #endif // SHARE_VM_OPTO_SUPERWORD_HPP