kc3-lang/libxkbcommon/src/xkbcomp/ast-build.h

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• Hash : 7c42945e
  Author :
  Date : 2019-11-13T22:41:38
  

  parser: fix quadratic pointer chasing In the AST, lists (e.g. the list of statements in a file) are kept in singly-linked lists -- each AST node has a `next` pointer available for this purpose. Previously, a node was added to the list by starting from the head, chasing to the last, and appending. So creating a list of length N would take ~N^2/2 pointer dereferences. Now, we always (temporarily) keep the last as well, so appending is O(1) instead of O(N). Given a keymap xkb_keymap { xkb_keycodes { minimum = 8; minimum = 8; minimum = 8; minimum = 8; minimum = 8; [... repeated N times ...] }; xkb_types {}; xkb_compat {}; xkb_symbols {}; }; The compilation times are N | Before | After --------|----------|------- 10,000 | 0.407s | 0.006s 20,000 | 1.851s | 0.015s 30,000 | 5.737s | 0.021s 40,000 | 12.759s | 0.023s 50,000 | 21.489s | 0.035s 60,000 | 40.473s | 0.041s 70,000 | 53.336s | 0.039s 80,000 | 72.485s | 0.044s 90,000 | 94.703s | 0.048s 100,000 | 118.390s | 0.057s Another option is to ditch the linked lists and use arrays instead. I got it to work, but its more involved and allocation heavy so turns out to be worse without further optimizations. Signed-off-by: Ran Benita <ran@unusedvar.com>

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• src/xkbcomp/ast-build.h

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   * Copyright (c) 1994 by Silicon Graphics Computer Systems, Inc.
   *
   * Permission to use, copy, modify, and distribute this
   * software and its documentation for any purpose and without
   * fee is hereby granted, provided that the above copyright
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  #ifndef XKBCOMP_AST_BUILD_H
  #define XKBCOMP_AST_BUILD_H
  
  ExprDef *
  ExprCreateString(xkb_atom_t str);
  
  ExprDef *
  ExprCreateInteger(int ival);
  
  ExprDef *
  ExprCreateFloat(void);
  
  ExprDef *
  ExprCreateBoolean(bool set);
  
  ExprDef *
  ExprCreateKeyName(xkb_atom_t key_name);
  
  ExprDef *
  ExprCreateIdent(xkb_atom_t ident);
  
  ExprDef *
  ExprCreateUnary(enum expr_op_type op, enum expr_value_type type,
                  ExprDef *child);
  
  ExprDef *
  ExprCreateBinary(enum expr_op_type op, ExprDef *left, ExprDef *right);
  
  ExprDef *
  ExprCreateFieldRef(xkb_atom_t element, xkb_atom_t field);
  
  ExprDef *
  ExprCreateArrayRef(xkb_atom_t element, xkb_atom_t field, ExprDef *entry);
  
  ExprDef *
  ExprCreateAction(xkb_atom_t name, ExprDef *args);
  
  ExprDef *
  ExprCreateActionList(ExprDef *actions);
  
  ExprDef *
  ExprCreateMultiKeysymList(ExprDef *list);
  
  ExprDef *
  ExprCreateKeysymList(xkb_keysym_t sym);
  
  ExprDef *
  ExprAppendMultiKeysymList(ExprDef *list, ExprDef *append);
  
  ExprDef *
  ExprAppendKeysymList(ExprDef *list, xkb_keysym_t sym);
  
  KeycodeDef *
  KeycodeCreate(xkb_atom_t name, int64_t value);
  
  KeyAliasDef *
  KeyAliasCreate(xkb_atom_t alias, xkb_atom_t real);
  
  VModDef *
  VModCreate(xkb_atom_t name, ExprDef *value);
  
  VarDef *
  VarCreate(ExprDef *name, ExprDef *value);
  
  VarDef *
  BoolVarCreate(xkb_atom_t ident, bool set);
  
  InterpDef *
  InterpCreate(xkb_keysym_t sym, ExprDef *match);
  
  KeyTypeDef *
  KeyTypeCreate(xkb_atom_t name, VarDef *body);
  
  SymbolsDef *
  SymbolsCreate(xkb_atom_t keyName, VarDef *symbols);
  
  GroupCompatDef *
  GroupCompatCreate(unsigned group, ExprDef *def);
  
  ModMapDef *
  ModMapCreate(xkb_atom_t modifier, ExprDef *keys);
  
  LedMapDef *
  LedMapCreate(xkb_atom_t name, VarDef *body);
  
  LedNameDef *
  LedNameCreate(unsigned ndx, ExprDef *name, bool virtual);
  
  IncludeStmt *
  IncludeCreate(struct xkb_context *ctx, char *str, enum merge_mode merge);
  
  XkbFile *
  XkbFileCreate(enum xkb_file_type type, char *name, ParseCommon *defs,
                enum xkb_map_flags flags);
  
  void
  FreeStmt(ParseCommon *stmt);
  
  #endif
  

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