/*

 * Copyright 2007 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

//

//                  S U P E R W O R D   T R A N S F O R M

//

// SuperWords are short, fixed length vectors.

//

// Algorithm from:

//

// Exploiting SuperWord Level Parallelism with

//   Multimedia Instruction Sets

// by

//   Samuel Larsen and Saman Amarasighe

//   MIT Laboratory for Computer Science

// date

//   May 2000

// published in

//   ACM SIGPLAN Notices

//   Proceedings of ACM PLDI '00,  Volume 35 Issue 5

//

// Definition 3.1 A Pack is an n-tuple, <s1, ...,sn>, where

// s1,...,sn are independent isomorphic statements in a basic

// block.

//

// Definition 3.2 A PackSet is a set of Packs.

//

// Definition 3.3 A Pair is a Pack of size two, where the

// first statement is considered the left element, and the

// second statement is considered the right element.

class SWPointer;

class OrderedPair;

// ========================= Dependence Graph =====================

class DepMem;

//------------------------------DepEdge---------------------------

// An edge in the dependence graph.  The edges incident to a dependence

// node are threaded through _next_in for incoming edges and _next_out

// for outgoing edges.

class DepEdge : public ResourceObj {

 protected:

  DepMem* _pred;

  DepMem* _succ;

  DepEdge* _next_in;   // list of in edges, null terminated

  DepEdge* _next_out;  // list of out edges, null terminated

 public:

  DepEdge(DepMem* pred, DepMem* succ, DepEdge* next_in, DepEdge* next_out) :

    _pred(pred), _succ(succ), _next_in(next_in), _next_out(next_out) {}

  DepEdge* next_in()  { return _next_in; }

  DepEdge* next_out() { return _next_out; }

  DepMem*  pred()     { return _pred; }

  DepMem*  succ()     { return _succ; }

  void print();

};

//------------------------------DepMem---------------------------

// A node in the dependence graph.  _in_head starts the threaded list of

// incoming edges, and _out_head starts the list of outgoing edges.

class DepMem : public ResourceObj {

 protected:

  Node*    _node;     // Corresponding ideal node

  DepEdge* _in_head;  // Head of list of in edges, null terminated

  DepEdge* _out_head; // Head of list of out edges, null terminated

 public:

  DepMem(Node* node) : _node(node), _in_head(NULL), _out_head(NULL) {}

  Node*    node()                { return _node;     }

  DepEdge* in_head()             { return _in_head;  }

  DepEdge* out_head()            { return _out_head; }

  void set_in_head(DepEdge* hd)  { _in_head = hd;    }

  void set_out_head(DepEdge* hd) { _out_head = hd;   }

  int in_cnt();  // Incoming edge count

  int out_cnt(); // Outgoing edge count

  void print();

};

//------------------------------DepGraph---------------------------

class DepGraph VALUE_OBJ_CLASS_SPEC {

 protected:

  Arena* _arena;

  GrowableArray<DepMem*> _map;

  DepMem* _root;

  DepMem* _tail;

 public:

  DepGraph(Arena* a) : _arena(a), _map(a, 8,  0, NULL) {

    _root = new (_arena) DepMem(NULL);

    _tail = new (_arena) DepMem(NULL);

  }

  DepMem* root() { return _root; }

  DepMem* tail() { return _tail; }

  // Return dependence node corresponding to an ideal node

  DepMem* dep(Node* node) { return _map.at(node->_idx); }

  // Make a new dependence graph node for an ideal node.

  DepMem* make_node(Node* node);

  // Make a new dependence graph edge dprec->dsucc

  DepEdge* make_edge(DepMem* dpred, DepMem* dsucc);

  DepEdge* make_edge(Node* pred,   Node* succ)   { return make_edge(dep(pred), dep(succ)); }

  DepEdge* make_edge(DepMem* pred, Node* succ)   { return make_edge(pred,      dep(succ)); }

  DepEdge* make_edge(Node* pred,   DepMem* succ) { return make_edge(dep(pred), succ);      }

  void init() { _map.clear(); } // initialize

  void print(Node* n)   { dep(n)->print(); }

  void print(DepMem* d) { d->print(); }

};

//------------------------------DepPreds---------------------------

// Iterator over predecessors in the dependence graph and

// non-memory-graph inputs of ideal nodes.

class DepPreds : public StackObj {

private:

  Node*    _n;

  int      _next_idx, _end_idx;

  DepEdge* _dep_next;

  Node*    _current;

  bool     _done;

public:

  DepPreds(Node* n, DepGraph& dg);

  Node* current() { return _current; }

  bool  done()    { return _done; }

  void  next();

};

//------------------------------DepSuccs---------------------------

// Iterator over successors in the dependence graph and

// non-memory-graph outputs of ideal nodes.

class DepSuccs : public StackObj {

private:

  Node*    _n;

  int      _next_idx, _end_idx;

  DepEdge* _dep_next;

  Node*    _current;

  bool     _done;

public:

  DepSuccs(Node* n, DepGraph& dg);

  Node* current() { return _current; }

  bool  done()    { return _done; }

  void  next();

};

// ========================= SuperWord =====================

// -----------------------------SWNodeInfo---------------------------------

// Per node info needed by SuperWord

class SWNodeInfo VALUE_OBJ_CLASS_SPEC {

 public:

  int         _alignment; // memory alignment for a node

  int         _depth;     // Max expression (DAG) depth from block start

  const Type* _velt_type; // vector element type

  Node_List*  _my_pack;   // pack containing this node

  SWNodeInfo() : _alignment(-1), _depth(0), _velt_type(NULL), _my_pack(NULL) {}

  static const SWNodeInfo initial;

};

// -----------------------------SuperWord---------------------------------

// Transforms scalar operations into packed (superword) operations.

class SuperWord : public ResourceObj {

 private:

  PhaseIdealLoop* _phase;

  Arena*          _arena;

  PhaseIterGVN   &_igvn;

  enum consts { top_align = -1, bottom_align = -666 };

  GrowableArray<Node_List*> _packset;    // Packs for the current block

  GrowableArray<int> _bb_idx;            // Map from Node _idx to index within block

  GrowableArray<Node*> _block;           // Nodes in current block

  GrowableArray<Node*> _data_entry;      // Nodes with all inputs from outside

  GrowableArray<Node*> _mem_slice_head;  // Memory slice head nodes

  GrowableArray<Node*> _mem_slice_tail;  // Memory slice tail nodes

  GrowableArray<SWNodeInfo> _node_info;  // Info needed per node

  MemNode* _align_to_ref;                // Memory reference that pre-loop will align to

  GrowableArray<OrderedPair> _disjoint_ptrs; // runtime disambiguated pointer pairs

  DepGraph _dg; // Dependence graph

  // Scratch pads

  VectorSet    _visited;       // Visited set

  VectorSet    _post_visited;  // Post-visited set

  Node_Stack   _n_idx_list;    // List of (node,index) pairs

  GrowableArray<Node*> _nlist; // List of nodes

  GrowableArray<Node*> _stk;   // Stack of nodes

 public:

  SuperWord(PhaseIdealLoop* phase);

  void transform_loop(IdealLoopTree* lpt);

  // Accessors for SWPointer

  PhaseIdealLoop* phase()          { return _phase; }

  IdealLoopTree* lpt()             { return _lpt; }

  PhiNode* iv()                    { return _iv; }

 private:

  IdealLoopTree* _lpt;             // Current loop tree node

  LoopNode*      _lp;              // Current LoopNode

  Node*          _bb;              // Current basic block

  PhiNode*       _iv;              // Induction var

  // Accessors

  Arena* arena()                   { return _arena; }

  Node* bb()                       { return _bb; }

  void  set_bb(Node* bb)           { _bb = bb; }

  void set_lpt(IdealLoopTree* lpt) { _lpt = lpt; }

  LoopNode* lp()                   { return _lp; }

  void      set_lp(LoopNode* lp)   { _lp = lp;

                                     _iv = lp->as_CountedLoop()->phi()->as_Phi(); }

  int      iv_stride()             { return lp()->as_CountedLoop()->stride_con(); }

  int vector_width_in_bytes()      { return Matcher::vector_width_in_bytes(); }

  MemNode* align_to_ref()            { return _align_to_ref; }

  void  set_align_to_ref(MemNode* m) { _align_to_ref = m; }

  Node* ctrl(Node* n) const { return _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n; }

  // block accessors

  bool in_bb(Node* n)      { return n != NULL && n->outcnt() > 0 && ctrl(n) == _bb; }

  int  bb_idx(Node* n)     { assert(in_bb(n), "must be"); return _bb_idx.at(n->_idx); }

  void set_bb_idx(Node* n, int i) { _bb_idx.at_put_grow(n->_idx, i); }

  // visited set accessors

  void visited_clear()           { _visited.Clear(); }

  void visited_set(Node* n)      { return _visited.set(bb_idx(n)); }

  int visited_test(Node* n)      { return _visited.test(bb_idx(n)); }

  int visited_test_set(Node* n)  { return _visited.test_set(bb_idx(n)); }

  void post_visited_clear()      { _post_visited.Clear(); }

  void post_visited_set(Node* n) { return _post_visited.set(bb_idx(n)); }

  int post_visited_test(Node* n) { return _post_visited.test(bb_idx(n)); }

  // Ensure node_info contains element "i"

  void grow_node_info(int i) { if (i >= _node_info.length()) _node_info.at_put_grow(i, SWNodeInfo::initial); }

  // memory alignment for a node

  int alignment(Node* n)                     { return _node_info.adr_at(bb_idx(n))->_alignment; }

  void set_alignment(Node* n, int a)         { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_alignment = a; }

  // Max expression (DAG) depth from beginning of the block for each node

  int depth(Node* n)                         { return _node_info.adr_at(bb_idx(n))->_depth; }

  void set_depth(Node* n, int d)             { int i = bb_idx(n); grow_node_info(i); _node_info.adr_at(i)->_depth = d; }

  // vector element type

  const Type* velt_type(Node* n)             { return _node_info.adr_at(bb_idx(n))->_velt_type; }

  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; }

  // my_pack

  Node_List* my_pack(Node* n)                { return !in_bb(n) ? NULL : _node_info.adr_at(bb_idx(n))->_my_pack; }

  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; }

  // methods

  // Extract the superword level parallelism

  void SLP_extract();

  // Find the adjacent memory references and create pack pairs for them.

  void find_adjacent_refs();

  // Find a memory reference to align the loop induction variable to.

  void find_align_to_ref(Node_List &memops);

  // Can the preloop align the reference to position zero in the vector?

  bool ref_is_alignable(SWPointer& p);

  // Construct dependency graph.

  void dependence_graph();

  // Return a memory slice (node list) in predecessor order starting at "start"

  void mem_slice_preds(Node* start, Node* stop, GrowableArray<Node*> &preds);

  // Can s1 and s2 be in a pack with s1 immediately preceeding s2 and  s1 aligned at "align"

  bool stmts_can_pack(Node* s1, Node* s2, int align);

  // Does s exist in a pack at position pos?

  bool exists_at(Node* s, uint pos);

  // Is s1 immediately before s2 in memory?

  bool are_adjacent_refs(Node* s1, Node* s2);

  // Are s1 and s2 similar?

  bool isomorphic(Node* s1, Node* s2);

  // Is there no data path from s1 to s2 or s2 to s1?

  bool independent(Node* s1, Node* s2);

  // Helper for independent

  bool independent_path(Node* shallow, Node* deep, uint dp=0);

  void set_alignment(Node* s1, Node* s2, int align);

  int data_size(Node* s);

  // Extend packset by following use->def and def->use links from pack members.

  void extend_packlist();

  // Extend the packset by visiting operand definitions of nodes in pack p

  bool follow_use_defs(Node_List* p);

  // Extend the packset by visiting uses of nodes in pack p

  bool follow_def_uses(Node_List* p);

  // Estimate the savings from executing s1 and s2 as a pack

  int est_savings(Node* s1, Node* s2);

  int adjacent_profit(Node* s1, Node* s2);

  int pack_cost(int ct);

  int unpack_cost(int ct);

  // Combine packs A and B with A.last == B.first into A.first..,A.last,B.second,..B.last

  void combine_packs();

  // Construct the map from nodes to packs.

  void construct_my_pack_map();

  // Remove packs that are not implemented or not profitable.

  void filter_packs();

  // Adjust the memory graph for the packed operations

  void schedule();

  // Within a pack, move stores down to the last executed store,

  // and move loads up to the first executed load.

  void co_locate_pack(Node_List* p);

  // Convert packs into vector node operations

  void output();

  // Create a vector operand for the nodes in pack p for operand: in(opd_idx)

  VectorNode* vector_opd(Node_List* p, int opd_idx);

  // Can code be generated for pack p?

  bool implemented(Node_List* p);

  // For pack p, are all operands and all uses (with in the block) vector?

  bool profitable(Node_List* p);

  // If a use of pack p is not a vector use, then replace the use with an extract operation.

  void insert_extracts(Node_List* p);

  // Is use->in(u_idx) a vector use?

  bool is_vector_use(Node* use, int u_idx);

  // Construct reverse postorder list of block members

  void construct_bb();

  // Initialize per node info

  void initialize_bb();

  // Insert n into block after pos

  void bb_insert_after(Node* n, int pos);

  // Compute max depth for expressions from beginning of block

  void compute_max_depth();

  // Compute necessary vector element type for expressions

  void compute_vector_element_type();

  // Are s1 and s2 in a pack pair and ordered as s1,s2?

  bool in_packset(Node* s1, Node* s2);

  // Is s in pack p?

  Node_List* in_pack(Node* s, Node_List* p);

  // Remove the pack at position pos in the packset

  void remove_pack_at(int pos);

  // Return the node executed first in pack p.

  Node* executed_first(Node_List* p);

  // Return the node executed last in pack p.

  Node* executed_last(Node_List* p);

  // Alignment within a vector memory reference

  int memory_alignment(MemNode* s, int iv_adjust_in_bytes);

  // (Start, end] half-open range defining which operands are vector

  void vector_opd_range(Node* n, uint* start, uint* end);

  // Smallest type containing range of values

  static const Type* container_type(const Type* t);

  // Adjust pre-loop limit so that in main loop, a load/store reference

  // to align_to_ref will be a position zero in the vector.

  void align_initial_loop_index(MemNode* align_to_ref);

  // Find pre loop end from main loop.  Returns null if none.

  CountedLoopEndNode* get_pre_loop_end(CountedLoopNode *cl);

  // Is the use of d1 in u1 at the same operand position as d2 in u2?

  bool opnd_positions_match(Node* d1, Node* u1, Node* d2, Node* u2);

  void init();

  // print methods

  void print_packset();

  void print_pack(Node_List* p);

  void print_bb();

  void print_stmt(Node* s);

  char* blank(uint depth);

};

//------------------------------SWPointer---------------------------

// Information about an address for dependence checking and vector alignment

class SWPointer VALUE_OBJ_CLASS_SPEC {

 protected:

  MemNode*   _mem;     // My memory reference node

  SuperWord* _slp;     // SuperWord class

  Node* _base;         // NULL if unsafe nonheap reference

  Node* _adr;          // address pointer

  jint  _scale;        // multipler for iv (in bytes), 0 if no loop iv

  jint  _offset;       // constant offset (in bytes)

  Node* _invar;        // invariant offset (in bytes), NULL if none

  bool  _negate_invar; // if true then use: (0 - _invar)

  PhaseIdealLoop* phase() { return _slp->phase(); }

  IdealLoopTree*  lpt()   { return _slp->lpt(); }

  PhiNode*        iv()    { return _slp->iv();  } // Induction var

  bool invariant(Node* n) {

    Node *n_c = phase()->get_ctrl(n);

    return !lpt()->is_member(phase()->get_loop(n_c));

  }

  // Match: k*iv + offset

  bool scaled_iv_plus_offset(Node* n);

  // Match: k*iv where k is a constant that's not zero

  bool scaled_iv(Node* n);

  // Match: offset is (k [+/- invariant])

  bool offset_plus_k(Node* n, bool negate = false);

 public:

  enum CMP {

    Less          = 1,

    Greater       = 2,

    Equal         = 4,

    NotEqual      = (Less | Greater),

    NotComparable = (Less | Greater | Equal)

  };

  SWPointer(MemNode* mem, SuperWord* slp);

  // Following is used to create a temporary object during

  // the pattern match of an address expression.

  SWPointer(SWPointer* p);

  bool valid()  { return _adr != NULL; }

  bool has_iv() { return _scale != 0; }

  Node* base()            { return _base; }

  Node* adr()             { return _adr; }

  int   scale_in_bytes()  { return _scale; }

  Node* invar()           { return _invar; }

  bool  negate_invar()    { return _negate_invar; }

  int   offset_in_bytes() { return _offset; }

  int   memory_size()     { return _mem->memory_size(); }

  // Comparable?

  int cmp(SWPointer& q) {

    if (valid() && q.valid() &&

        (_adr == q._adr || _base == _adr && q._base == q._adr) &&

        _scale == q._scale   &&

        _invar == q._invar   &&

        _negate_invar == q._negate_invar) {

      bool overlap = q._offset <   _offset +   memory_size() &&

                       _offset < q._offset + q.memory_size();

      return overlap ? Equal : (_offset < q._offset ? Less : Greater);

    } else {

      return NotComparable;

    }

  }

  bool not_equal(SWPointer& q)    { return not_equal(cmp(q)); }

  bool equal(SWPointer& q)        { return equal(cmp(q)); }

  bool comparable(SWPointer& q)   { return comparable(cmp(q)); }

  static bool not_equal(int cmp)  { return cmp <= NotEqual; }

  static bool equal(int cmp)      { return cmp == Equal; }

  static bool comparable(int cmp) { return cmp < NotComparable; }

  void print();

};

//------------------------------OrderedPair---------------------------

// Ordered pair of Node*.

class OrderedPair VALUE_OBJ_CLASS_SPEC {

 protected:

  Node* _p1;

  Node* _p2;

 public:

  OrderedPair() : _p1(NULL), _p2(NULL) {}

  OrderedPair(Node* p1, Node* p2) {

    if (p1->_idx < p2->_idx) {

      _p1 = p1; _p2 = p2;

    } else {

      _p1 = p2; _p2 = p1;

    }

  }

  bool operator==(const OrderedPair &rhs) {

    return _p1 == rhs._p1 && _p2 == rhs._p2;

  }

  void print() { tty->print("  (%d, %d)", _p1->_idx, _p2->_idx); }

  static const OrderedPair initial;

};