/*

 * Copyright 2000-2005 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.

 *

 */

//---------------------------CallGenerator-------------------------------------

// The subclasses of this class handle generation of ideal nodes for

// call sites and method entry points.

class CallGenerator : public ResourceObj {

 public:

  enum {

    xxxunusedxxx

  };

 private:

  ciMethod*             _method;                // The method being called.

 protected:

  CallGenerator(ciMethod* method);

 public:

  // Accessors

  ciMethod*         method() const              { return _method; }

  // is_inline: At least some code implementing the method is copied here.

  virtual bool      is_inline() const           { return false; }

  // is_intrinsic: There's a method-specific way of generating the inline code.

  virtual bool      is_intrinsic() const        { return false; }

  // is_parse: Bytecodes implementing the specific method are copied here.

  virtual bool      is_parse() const            { return false; }

  // is_virtual: The call uses the receiver type to select or check the method.

  virtual bool      is_virtual() const          { return false; }

  // is_deferred: The decision whether to inline or not is deferred.

  virtual bool      is_deferred() const         { return false; }

  // is_predicted: Uses an explicit check against a predicted type.

  virtual bool      is_predicted() const        { return false; }

  // is_trap: Does not return to the caller.  (E.g., uncommon trap.)

  virtual bool      is_trap() const             { return false; }

  // Note:  It is possible for a CG to be both inline and virtual.

  // (The hashCode intrinsic does a vtable check and an inlined fast path.)

  // Utilities:

  const TypeFunc*   tf() const;

  // The given jvms has state and arguments for a call to my method.

  // Edges after jvms->argoff() carry all (pre-popped) argument values.

  //

  // Update the map with state and return values (if any) and return it.

  // The return values (0, 1, or 2) must be pushed on the map's stack,

  // and the sp of the jvms incremented accordingly.

  //

  // The jvms is returned on success.  Alternatively, a copy of the

  // given jvms, suitably updated, may be returned, in which case the

  // caller should discard the original jvms.

  //

  // The non-Parm edges of the returned map will contain updated global state,

  // and one or two edges before jvms->sp() will carry any return values.

  // Other map edges may contain locals or monitors, and should not

  // be changed in meaning.

  //

  // If the call traps, the returned map must have a control edge of top.

  // If the call can throw, the returned map must report has_exceptions().

  //

  // If the result is NULL, it means that this CallGenerator was unable

  // to handle the given call, and another CallGenerator should be consulted.

  virtual JVMState* generate(JVMState* jvms) = 0;

  // How to generate a call site that is inlined:

  static CallGenerator* for_inline(ciMethod* m, float expected_uses = -1);

  // How to generate code for an on-stack replacement handler.

  static CallGenerator* for_osr(ciMethod* m, int osr_bci);

  // How to generate vanilla out-of-line call sites:

  static CallGenerator* for_direct_call(ciMethod* m);   // static, special

  static CallGenerator* for_virtual_call(ciMethod* m, int vtable_index);  // virtual, interface

  // How to make a call but defer the decision whether to inline or not.

  static CallGenerator* for_warm_call(WarmCallInfo* ci,

                                      CallGenerator* if_cold,

                                      CallGenerator* if_hot);

  // How to make a call that optimistically assumes a receiver type:

  static CallGenerator* for_predicted_call(ciKlass* predicted_receiver,

                                           CallGenerator* if_missed,

                                           CallGenerator* if_hit,

                                           float hit_prob);

  // How to make a call that gives up and goes back to the interpreter:

  static CallGenerator* for_uncommon_trap(ciMethod* m,

                                          Deoptimization::DeoptReason reason,

                                          Deoptimization::DeoptAction action);

  // Registry for intrinsics:

  static CallGenerator* for_intrinsic(ciMethod* m);

  static void register_intrinsic(ciMethod* m, CallGenerator* cg);

};

class InlineCallGenerator : public CallGenerator {

  virtual bool      is_inline() const           { return true; }

 protected:

  InlineCallGenerator(ciMethod* method) : CallGenerator(method) { }

};

//---------------------------WarmCallInfo--------------------------------------

// A struct to collect information about a given call site.

// Helps sort call sites into "hot", "medium", and "cold".

// Participates in the queueing of "medium" call sites for possible inlining.

class WarmCallInfo : public ResourceObj {

 private:

  CallNode*     _call;   // The CallNode which may be inlined.

  CallGenerator* _hot_cg;// CG for expanding the call node

  // These are the metrics we use to evaluate call sites:

  float         _count;  // How often do we expect to reach this site?

  float         _profit; // How much time do we expect to save by inlining?

  float         _work;   // How long do we expect the average call to take?

  float         _size;   // How big do we expect the inlined code to be?

  float         _heat;   // Combined score inducing total order on call sites.

  WarmCallInfo* _next;   // Next cooler call info in pending queue.

  // Count is the number of times this call site is expected to be executed.

  // Large count is favorable for inlining, because the extra compilation

  // work will be amortized more completely.

  // Profit is a rough measure of the amount of time we expect to save

  // per execution of this site if we inline it.  (1.0 == call overhead)

  // Large profit favors inlining.  Negative profit disables inlining.

  // Work is a rough measure of the amount of time a typical out-of-line

  // call from this site is expected to take.  (1.0 == call, no-op, return)

  // Small work is somewhat favorable for inlining, since methods with

  // short "hot" traces are more likely to inline smoothly.

  // Size is the number of graph nodes we expect this method to produce,

  // not counting the inlining of any further warm calls it may include.

  // Small size favors inlining, since small methods are more likely to

  // inline smoothly.  The size is estimated by examining the native code

  // if available.  The method bytecodes are also examined, assuming

  // empirically observed node counts for each kind of bytecode.

  // Heat is the combined "goodness" of a site's inlining.  If we were

  // omniscient, it would be the difference of two sums of future execution

  // times of code emitted for this site (amortized across multiple sites if

  // sharing applies).  The two sums are for versions of this call site with

  // and without inlining.

  // We approximate this mythical quantity by playing with averages,

  // rough estimates, and assumptions that history repeats itself.

  // The basic formula count * profit is heuristically adjusted

  // by looking at the expected compilation and execution times of

  // of the inlined call.

  // Note:  Some of these metrics may not be present in the final product,

  // but exist in development builds to experiment with inline policy tuning.

  // This heuristic framework does not model well the very significant

  // effects of multiple-level inlining.  It is possible to see no immediate

  // profit from inlining X->Y, but to get great profit from a subsequent

  // inlining X->Y->Z.

  // This framework does not take well into account the problem of N**2 code

  // size in a clique of mutually inlinable methods.

  WarmCallInfo*  next() const          { return _next; }

  void       set_next(WarmCallInfo* n) { _next = n; }

  static WarmCallInfo* _always_hot;

  static WarmCallInfo* _always_cold;

 public:

  // Because WarmInfo objects live over the entire lifetime of the

  // Compile object, they are allocated into the comp_arena, which

  // does not get resource marked or reset during the compile process

  void *operator new( size_t x, Compile* C ) { return C->comp_arena()->Amalloc(x); }

  void operator delete( void * ) { } // fast deallocation

  static WarmCallInfo* always_hot();

  static WarmCallInfo* always_cold();

  WarmCallInfo() {

    _call = NULL;

    _hot_cg = NULL;

    _next = NULL;

    _count = _profit = _work = _size = _heat = 0;

  }

  CallNode* call() const { return _call; }

  float count()    const { return _count; }

  float size()     const { return _size; }

  float work()     const { return _work; }

  float profit()   const { return _profit; }

  float heat()     const { return _heat; }

  void set_count(float x)     { _count = x; }

  void set_size(float x)      { _size = x; }

  void set_work(float x)      { _work = x; }

  void set_profit(float x)    { _profit = x; }

  void set_heat(float x)      { _heat = x; }

  // Load initial heuristics from profiles, etc.

  // The heuristics can be tweaked further by the caller.

  void init(JVMState* call_site, ciMethod* call_method, ciCallProfile& profile, float prof_factor);

  static float MAX_VALUE() { return +1.0e10; }

  static float MIN_VALUE() { return -1.0e10; }

  float compute_heat() const;

  void set_call(CallNode* call)      { _call = call; }

  void set_hot_cg(CallGenerator* cg) { _hot_cg = cg; }

  // Do not queue very hot or very cold calls.

  // Make very cold ones out of line immediately.

  // Inline very hot ones immediately.

  // These queries apply various tunable limits

  // to the above metrics in a systematic way.

  // Test for coldness before testing for hotness.

  bool is_cold() const;

  bool is_hot() const;

  // Force a warm call to be hot.  This worklists the call node for inlining.

  void make_hot();

  // Force a warm call to be cold.  This worklists the call node for out-of-lining.

  void make_cold();

  // A reproducible total ordering, in which heat is the major key.

  bool warmer_than(WarmCallInfo* that);

  // List management.  These methods are called with the list head,

  // and return the new list head, inserting or removing the receiver.

  WarmCallInfo* insert_into(WarmCallInfo* head);

  WarmCallInfo* remove_from(WarmCallInfo* head);

#ifndef PRODUCT

  void print() const;

  void print_all() const;

  int count_all() const;

#endif

};