alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (parse.hpp)

This example Java source code file (parse.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

block, bytecodeparsehistogram, bytecodes\:\:code, inlinetree, invocationentrybci, jvmstate, node, null, parse, product, safepointnode, switchrange, type, warmcallinfo

The parse.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_OPTO_PARSE_HPP
#define SHARE_VM_OPTO_PARSE_HPP

#include "ci/ciMethodData.hpp"
#include "ci/ciTypeFlow.hpp"
#include "compiler/methodLiveness.hpp"
#include "libadt/vectset.hpp"
#include "oops/generateOopMap.hpp"
#include "opto/graphKit.hpp"
#include "opto/subnode.hpp"

class BytecodeParseHistogram;
class InlineTree;
class Parse;
class SwitchRange;


//------------------------------InlineTree-------------------------------------
class InlineTree : public ResourceObj {
  friend class VMStructs;

  Compile*    C;                  // cache
  JVMState*   _caller_jvms;       // state of caller
  ciMethod*   _method;            // method being called by the caller_jvms
  InlineTree* _caller_tree;
  uint        _count_inline_bcs;  // Accumulated count of inlined bytecodes
  // Call-site count / interpreter invocation count, scaled recursively.
  // Always between 0.0 and 1.0.  Represents the percentage of the method's
  // total execution time used at this call site.
  const float _site_invoke_ratio;
  const int   _max_inline_level;  // the maximum inline level for this sub-tree (may be adjusted)
  float compute_callee_frequency( int caller_bci ) const;

  GrowableArray<InlineTree*> _subtrees;

  void print_impl(outputStream* stj, int indent) const PRODUCT_RETURN;
  const char* _msg;
protected:
  InlineTree(Compile* C,
             const InlineTree* caller_tree,
             ciMethod* callee_method,
             JVMState* caller_jvms,
             int caller_bci,
             float site_invoke_ratio,
             int max_inline_level);
  InlineTree *build_inline_tree_for_callee(ciMethod* callee_method,
                                           JVMState* caller_jvms,
                                           int caller_bci);
  bool        try_to_inline(ciMethod* callee_method,
                            ciMethod* caller_method,
                            int caller_bci,
                            JVMState* jvms,
                            ciCallProfile& profile,
                            WarmCallInfo* wci_result,
                            bool& should_delay);
  bool        should_inline(ciMethod* callee_method,
                            ciMethod* caller_method,
                            int caller_bci,
                            ciCallProfile& profile,
                            WarmCallInfo* wci_result);
  bool        should_not_inline(ciMethod* callee_method,
                                ciMethod* caller_method,
                                JVMState* jvms,
                                WarmCallInfo* wci_result);
  void        print_inlining(ciMethod* callee_method, int caller_bci,
                             bool success) const;

  InlineTree* caller_tree()       const { return _caller_tree;  }
  InlineTree* callee_at(int bci, ciMethod* m) const;
  int         inline_level()      const { return stack_depth(); }
  int         stack_depth()       const { return _caller_jvms ? _caller_jvms->depth() : 0; }
  const char* msg()               const { return _msg; }
  void        set_msg(const char* msg)  { _msg = msg; }
public:
  static const char* check_can_parse(ciMethod* callee);

  static InlineTree* build_inline_tree_root();
  static InlineTree* find_subtree_from_root(InlineTree* root, JVMState* jvms, ciMethod* callee);

  // For temporary (stack-allocated, stateless) ilts:
  InlineTree(Compile* c, ciMethod* callee_method, JVMState* caller_jvms, float site_invoke_ratio, int max_inline_level);

  // InlineTree enum
  enum InlineStyle {
    Inline_do_not_inline             =   0, //
    Inline_cha_is_monomorphic        =   1, //
    Inline_type_profile_monomorphic  =   2  //
  };

  // See if it is OK to inline.
  // The receiver is the inline tree for the caller.
  //
  // The result is a temperature indication.  If it is hot or cold,
  // inlining is immediate or undesirable.  Otherwise, the info block
  // returned is newly allocated and may be enqueued.
  //
  // If the method is inlinable, a new inline subtree is created on the fly,
  // and may be accessed by find_subtree_from_root.
  // The call_method is the dest_method for a special or static invocation.
  // The call_method is an optimized virtual method candidate otherwise.
  WarmCallInfo* ok_to_inline(ciMethod *call_method, JVMState* caller_jvms, ciCallProfile& profile, WarmCallInfo* wci, bool& should_delay);

  // Information about inlined method
  JVMState*   caller_jvms()       const { return _caller_jvms; }
  ciMethod   *method()            const { return _method; }
  int         caller_bci()        const { return _caller_jvms ? _caller_jvms->bci() : InvocationEntryBci; }
  uint        count_inline_bcs()  const { return _count_inline_bcs; }
  float       site_invoke_ratio() const { return _site_invoke_ratio; };

#ifndef PRODUCT
private:
  uint        _count_inlines;     // Count of inlined methods
public:
  // Debug information collected during parse
  uint        count_inlines()     const { return _count_inlines; };
#endif
  GrowableArray<InlineTree*> subtrees() { return _subtrees; }

  void print_value_on(outputStream* st) const PRODUCT_RETURN;
};


//-----------------------------------------------------------------------------
//------------------------------Parse------------------------------------------
// Parse bytecodes, build a Graph
class Parse : public GraphKit {
 public:
  // Per-block information needed by the parser:
  class Block {
   private:
    ciTypeFlow::Block* _flow;
    int                _pred_count;     // how many predecessors in CFG?
    int                _preds_parsed;   // how many of these have been parsed?
    uint               _count;          // how many times executed?  Currently only set by _goto's
    bool               _is_parsed;      // has this block been parsed yet?
    bool               _is_handler;     // is this block an exception handler?
    bool               _has_merged_backedge; // does this block have merged backedge?
    SafePointNode*     _start_map;      // all values flowing into this block
    MethodLivenessResult _live_locals;  // lazily initialized liveness bitmap

    int                _num_successors; // Includes only normal control flow.
    int                _all_successors; // Include exception paths also.
    Block**            _successors;

    // Use init_node/init_graph to initialize Blocks.
    // Block() : _live_locals((uintptr_t*)NULL,0) { ShouldNotReachHere(); }
    Block() : _live_locals(NULL,0) { ShouldNotReachHere(); }

   public:

    // Set up the block data structure itself.
    void init_node(Parse* outer, int po);
    // Set up the block's relations to other blocks.
    void init_graph(Parse* outer);

    ciTypeFlow::Block* flow() const        { return _flow; }
    int pred_count() const                 { return _pred_count; }
    int preds_parsed() const               { return _preds_parsed; }
    bool is_parsed() const                 { return _is_parsed; }
    bool is_handler() const                { return _is_handler; }
    void set_count( uint x )               { _count = x; }
    uint count() const                     { return _count; }

    SafePointNode* start_map() const       { assert(is_merged(),"");   return _start_map; }
    void set_start_map(SafePointNode* m)   { assert(!is_merged(), ""); _start_map = m; }

    // True after any predecessor flows control into this block
    bool is_merged() const                 { return _start_map != NULL; }

#ifdef ASSERT
    // True after backedge predecessor flows control into this block
    bool has_merged_backedge() const       { return _has_merged_backedge; }
    void mark_merged_backedge(Block* pred) {
      assert(is_SEL_head(), "should be loop head");
      if (pred != NULL && is_SEL_backedge(pred)) {
        assert(is_parsed(), "block should be parsed before merging backedges");
        _has_merged_backedge = true;
      }
    }
#endif

    // True when all non-exception predecessors have been parsed.
    bool is_ready() const                  { return preds_parsed() == pred_count(); }

    int num_successors() const             { return _num_successors; }
    int all_successors() const             { return _all_successors; }
    Block* successor_at(int i) const {
      assert((uint)i < (uint)all_successors(), "");
      return _successors[i];
    }
    Block* successor_for_bci(int bci);

    int start() const                      { return flow()->start(); }
    int limit() const                      { return flow()->limit(); }
    int rpo() const                        { return flow()->rpo(); }
    int start_sp() const                   { return flow()->stack_size(); }

    bool is_loop_head() const              { return flow()->is_loop_head(); }
    bool is_SEL_head() const               { return flow()->is_single_entry_loop_head(); }
    bool is_SEL_backedge(Block* pred) const{ return is_SEL_head() && pred->rpo() >= rpo(); }
    bool is_invariant_local(uint i) const  {
      const JVMState* jvms = start_map()->jvms();
      if (!jvms->is_loc(i) || flow()->outer()->has_irreducible_entry()) return false;
      return flow()->is_invariant_local(i - jvms->locoff());
    }
    bool can_elide_SEL_phi(uint i) const  { assert(is_SEL_head(),""); return is_invariant_local(i); }

    const Type* peek(int off=0) const      { return stack_type_at(start_sp() - (off+1)); }

    const Type* stack_type_at(int i) const;
    const Type* local_type_at(int i) const;
    static const Type* get_type(ciType* t) { return Type::get_typeflow_type(t); }

    bool has_trap_at(int bci) const        { return flow()->has_trap() && flow()->trap_bci() == bci; }

    // Call this just before parsing a block.
    void mark_parsed() {
      assert(!_is_parsed, "must parse each block exactly once");
      _is_parsed = true;
    }

    // Return the phi/region input index for the "current" pred,
    // and bump the pred number.  For historical reasons these index
    // numbers are handed out in descending order.  The last index is
    // always PhiNode::Input (i.e., 1).  The value returned is known
    // as a "path number" because it distinguishes by which path we are
    // entering the block.
    int next_path_num() {
      assert(preds_parsed() < pred_count(), "too many preds?");
      return pred_count() - _preds_parsed++;
    }

    // Add a previously unaccounted predecessor to this block.
    // This operates by increasing the size of the block's region
    // and all its phi nodes (if any).  The value returned is a
    // path number ("pnum").
    int add_new_path();

    // Initialize me by recording the parser's map.  My own map must be NULL.
    void record_state(Parse* outer);
  };

#ifndef PRODUCT
  // BytecodeParseHistogram collects number of bytecodes parsed, nodes constructed, and transformations.
  class BytecodeParseHistogram : public ResourceObj {
   private:
    enum BPHType {
      BPH_transforms,
      BPH_values
    };
    static bool _initialized;
    static uint _bytecodes_parsed [Bytecodes::number_of_codes];
    static uint _nodes_constructed[Bytecodes::number_of_codes];
    static uint _nodes_transformed[Bytecodes::number_of_codes];
    static uint _new_values       [Bytecodes::number_of_codes];

    Bytecodes::Code _initial_bytecode;
    int             _initial_node_count;
    int             _initial_transforms;
    int             _initial_values;

    Parse     *_parser;
    Compile   *_compiler;

    // Initialization
    static void reset();

    // Return info being collected, select with global flag 'BytecodeParseInfo'
    int current_count(BPHType info_selector);

   public:
    BytecodeParseHistogram(Parse *p, Compile *c);
    static bool initialized();

    // Record info when starting to parse one bytecode
    void set_initial_state( Bytecodes::Code bc );
    // Record results of parsing one bytecode
    void record_change();

    // Profile printing
    static void print(float cutoff = 0.01F); // cutoff in percent
  };

  public:
    // Record work done during parsing
    BytecodeParseHistogram* _parse_histogram;
    void set_parse_histogram(BytecodeParseHistogram *bph) { _parse_histogram = bph; }
    BytecodeParseHistogram* parse_histogram()      { return _parse_histogram; }
#endif

 private:
  friend class Block;

  // Variables which characterize this compilation as a whole:

  JVMState*     _caller;        // JVMS which carries incoming args & state.
  float         _expected_uses; // expected number of calls to this code
  float         _prof_factor;   // discount applied to my profile counts
  int           _depth;         // Inline tree depth, for debug printouts
  const TypeFunc*_tf;           // My kind of function type
  int           _entry_bci;     // the osr bci or InvocationEntryBci

  ciTypeFlow*   _flow;          // Results of previous flow pass.
  Block*        _blocks;        // Array of basic-block structs.
  int           _block_count;   // Number of elements in _blocks.

  GraphKit      _exits;         // Record all normal returns and throws here.
  bool          _wrote_final;   // Did we write a final field?
  bool          _count_invocations; // update and test invocation counter
  bool          _method_data_update; // update method data oop
  Node*         _alloc_with_final;   // An allocation node with final field

  // Variables which track Java semantics during bytecode parsing:

  Block*            _block;     // block currently getting parsed
  ciBytecodeStream  _iter;      // stream of this method's bytecodes

  int           _blocks_merged; // Progress meter: state merges from BB preds
  int           _blocks_parsed; // Progress meter: BBs actually parsed

  const FastLockNode* _synch_lock; // FastLockNode for synchronized method

#ifndef PRODUCT
  int _max_switch_depth;        // Debugging SwitchRanges.
  int _est_switch_depth;        // Debugging SwitchRanges.
#endif

  // parser for the caller of the method of this object
  Parse* const _parent;

 public:
  // Constructor
  Parse(JVMState* caller, ciMethod* parse_method, float expected_uses, Parse* parent);

  virtual Parse* is_Parse() const { return (Parse*)this; }

  // Accessors.
  JVMState*     caller()        const { return _caller; }
  float         expected_uses() const { return _expected_uses; }
  float         prof_factor()   const { return _prof_factor; }
  int           depth()         const { return _depth; }
  const TypeFunc* tf()          const { return _tf; }
  //            entry_bci()     -- see osr_bci, etc.

  ciTypeFlow*   flow()          const { return _flow; }
  //            blocks()        -- see rpo_at, start_block, etc.
  int           block_count()   const { return _block_count; }

  GraphKit&     exits()               { return _exits; }
  bool          wrote_final() const   { return _wrote_final; }
  void      set_wrote_final(bool z)   { _wrote_final = z; }
  bool          count_invocations() const  { return _count_invocations; }
  bool          method_data_update() const { return _method_data_update; }
  Node*    alloc_with_final() const   { return _alloc_with_final; }
  void set_alloc_with_final(Node* n)  {
    assert((_alloc_with_final == NULL) || (_alloc_with_final == n), "different init objects?");
    _alloc_with_final = n;
  }

  Block*             block()    const { return _block; }
  ciBytecodeStream&  iter()           { return _iter; }
  Bytecodes::Code    bc()       const { return _iter.cur_bc(); }

  void set_block(Block* b)            { _block = b; }

  // Derived accessors:
  bool is_normal_parse() const  { return _entry_bci == InvocationEntryBci; }
  bool is_osr_parse() const     { return _entry_bci != InvocationEntryBci; }
  int osr_bci() const           { assert(is_osr_parse(),""); return _entry_bci; }

  void set_parse_bci(int bci);

  // Must this parse be aborted?
  bool failing()                { return C->failing(); }

  Block* rpo_at(int rpo) {
    assert(0 <= rpo && rpo < _block_count, "oob");
    return &_blocks[rpo];
  }
  Block* start_block() {
    return rpo_at(flow()->start_block()->rpo());
  }
  // Can return NULL if the flow pass did not complete a block.
  Block* successor_for_bci(int bci) {
    return block()->successor_for_bci(bci);
  }

  Parse* parent_parser() const { return _parent; }

 private:
  // Create a JVMS & map for the initial state of this method.
  SafePointNode* create_entry_map();

  // OSR helpers
  Node *fetch_interpreter_state(int index, BasicType bt, Node *local_addrs, Node *local_addrs_base);
  Node* check_interpreter_type(Node* l, const Type* type, SafePointNode* &bad_type_exit);
  void  load_interpreter_state(Node* osr_buf);

  // Functions for managing basic blocks:
  void init_blocks();
  void load_state_from(Block* b);
  void store_state_to(Block* b) { b->record_state(this); }

  // Parse all the basic blocks.
  void do_all_blocks();

  // Parse the current basic block
  void do_one_block();

  // Raise an error if we get a bad ciTypeFlow CFG.
  void handle_missing_successor(int bci);

  // first actions (before BCI 0)
  void do_method_entry();

  // implementation of monitorenter/monitorexit
  void do_monitor_enter();
  void do_monitor_exit();

  // Eagerly create phie throughout the state, to cope with back edges.
  void ensure_phis_everywhere();

  // Merge the current mapping into the basic block starting at bci
  void merge(          int target_bci);
  // Same as plain merge, except that it allocates a new path number.
  void merge_new_path( int target_bci);
  // Merge the current mapping into an exception handler.
  void merge_exception(int target_bci);
  // Helper: Merge the current mapping into the given basic block
  void merge_common(Block* target, int pnum);
  // Helper functions for merging individual cells.
  PhiNode *ensure_phi(       int idx, bool nocreate = false);
  PhiNode *ensure_memory_phi(int idx, bool nocreate = false);
  // Helper to merge the current memory state into the given basic block
  void merge_memory_edges(MergeMemNode* n, int pnum, bool nophi);

  // Parse this bytecode, and alter the Parsers JVM->Node mapping
  void do_one_bytecode();

  // helper function to generate array store check
  void array_store_check();
  // Helper function to generate array load
  void array_load(BasicType etype);
  // Helper function to generate array store
  void array_store(BasicType etype);
  // Helper function to compute array addressing
  Node* array_addressing(BasicType type, int vals, const Type* *result2=NULL);

  // Pass current map to exits
  void return_current(Node* value);

  // Register finalizers on return from Object.<init>
  void call_register_finalizer();

  // Insert a compiler safepoint into the graph
  void add_safepoint();

  // Insert a compiler safepoint into the graph, if there is a back-branch.
  void maybe_add_safepoint(int target_bci) {
    if (UseLoopSafepoints && target_bci <= bci()) {
      add_safepoint();
    }
  }

  // Note:  Intrinsic generation routines may be found in library_call.cpp.

  // Helper function to setup Ideal Call nodes
  void do_call();

  // Helper function to uncommon-trap or bailout for non-compilable call-sites
  bool can_not_compile_call_site(ciMethod *dest_method, ciInstanceKlass *klass);

  // Helper function to setup for type-profile based inlining
  bool prepare_type_profile_inline(ciInstanceKlass* prof_klass, ciMethod* prof_method);

  // Helper functions for type checking bytecodes:
  void  do_checkcast();
  void  do_instanceof();

  // Helper functions for shifting & arithmetic
  void modf();
  void modd();
  void l2f();

  void do_irem();

  // implementation of _get* and _put* bytecodes
  void do_getstatic() { do_field_access(true,  false); }
  void do_getfield () { do_field_access(true,  true); }
  void do_putstatic() { do_field_access(false, false); }
  void do_putfield () { do_field_access(false, true); }

  // common code for making initial checks and forming addresses
  void do_field_access(bool is_get, bool is_field);
  bool static_field_ok_in_clinit(ciField *field, ciMethod *method);

  // common code for actually performing the load or store
  void do_get_xxx(Node* obj, ciField* field, bool is_field);
  void do_put_xxx(Node* obj, ciField* field, bool is_field);

  // loading from a constant field or the constant pool
  // returns false if push failed (non-perm field constants only, not ldcs)
  bool push_constant(ciConstant con, bool require_constant = false, bool is_autobox_cache = false, const Type* basic_type = NULL);

  // implementation of object creation bytecodes
  void emit_guard_for_new(ciInstanceKlass* klass);
  void do_new();
  void do_newarray(BasicType elemtype);
  void do_anewarray();
  void do_multianewarray();
  Node* expand_multianewarray(ciArrayKlass* array_klass, Node* *lengths, int ndimensions, int nargs);

  // implementation of jsr/ret
  void do_jsr();
  void do_ret();

  float   dynamic_branch_prediction(float &cnt);
  float   branch_prediction(float &cnt, BoolTest::mask btest, int target_bci);
  bool    seems_never_taken(float prob);
  bool    seems_stable_comparison(BoolTest::mask btest, Node* c);

  void    do_ifnull(BoolTest::mask btest, Node* c);
  void    do_if(BoolTest::mask btest, Node* c);
  int     repush_if_args();
  void    adjust_map_after_if(BoolTest::mask btest, Node* c, float prob,
                              Block* path, Block* other_path);
  void    sharpen_type_after_if(BoolTest::mask btest,
                                Node* con, const Type* tcon,
                                Node* val, const Type* tval);
  IfNode* jump_if_fork_int(Node* a, Node* b, BoolTest::mask mask);
  Node*   jump_if_join(Node* iffalse, Node* iftrue);
  void    jump_if_true_fork(IfNode *ifNode, int dest_bci_if_true, int prof_table_index);
  void    jump_if_false_fork(IfNode *ifNode, int dest_bci_if_false, int prof_table_index);
  void    jump_if_always_fork(int dest_bci_if_true, int prof_table_index);

  friend class SwitchRange;
  void    do_tableswitch();
  void    do_lookupswitch();
  void    jump_switch_ranges(Node* a, SwitchRange* lo, SwitchRange* hi, int depth = 0);
  bool    create_jump_tables(Node* a, SwitchRange* lo, SwitchRange* hi);

  // helper functions for methodData style profiling
  void test_counter_against_threshold(Node* cnt, int limit);
  void increment_and_test_invocation_counter(int limit);
  void test_for_osr_md_counter_at(ciMethodData* md, ciProfileData* data, ByteSize offset, int limit);
  Node* method_data_addressing(ciMethodData* md, ciProfileData* data, ByteSize offset, Node* idx = NULL, uint stride = 0);
  void increment_md_counter_at(ciMethodData* md, ciProfileData* data, ByteSize offset, Node* idx = NULL, uint stride = 0);
  void set_md_flag_at(ciMethodData* md, ciProfileData* data, int flag_constant);

  void profile_method_entry();
  void profile_taken_branch(int target_bci, bool force_update = false);
  void profile_not_taken_branch(bool force_update = false);
  void profile_call(Node* receiver);
  void profile_generic_call();
  void profile_receiver_type(Node* receiver);
  void profile_ret(int target_bci);
  void profile_null_checkcast();
  void profile_switch_case(int table_index);

  // helper function for call statistics
  void count_compiled_calls(bool at_method_entry, bool is_inline) PRODUCT_RETURN;

  Node_Notes* make_node_notes(Node_Notes* caller_nn);

  // Helper functions for handling normal and abnormal exits.
  void build_exits();

  // Fix up all exceptional control flow exiting a single bytecode.
  void do_exceptions();

  // Fix up all exiting control flow at the end of the parse.
  void do_exits();

  // Add Catch/CatchProjs
  // The call is either a Java call or the VM's rethrow stub
  void catch_call_exceptions(ciExceptionHandlerStream&);

  // Handle all exceptions thrown by the inlined method.
  // Also handles exceptions for individual bytecodes.
  void catch_inline_exceptions(SafePointNode* ex_map);

  // Merge the given map into correct exceptional exit state.
  // Assumes that there is no applicable local handler.
  void throw_to_exit(SafePointNode* ex_map);

  // Use speculative type to optimize CmpP node
  Node* optimize_cmp_with_klass(Node* c);

 public:
#ifndef PRODUCT
  // Handle PrintOpto, etc.
  void show_parse_info();
  void dump_map_adr_mem() const;
  static void print_statistics(); // Print some performance counters
  void dump();
  void dump_bci(int bci);
#endif
};

#endif // SHARE_VM_OPTO_PARSE_HPP

Other Java examples (source code examples)

Here is a short list of links related to this Java parse.hpp source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.