[PATCH] Reduce GC overhead of the C++ lexer buffer

[Richard Guenther]

At the moment we have

cp/parser.c:292 (cp_lexer_new_main)  0: 0.0%  82369152:33.3%  0: 0.0% 
15784576:37.2%  7

which is due to the fact that the initial lexer buffer size is no where
near a power-of-two value and we keep gc-reallocating the vector, doubling
its size.

With the following patch, this overhead is removed nearly completely

cp/parser.c:266 (cp_lexer_new_main)                       0: 0.0%         
36: 0.0%          0: 0.0%          4: 0.0%          1

Comments?

Thanks,
Richard.


2006-06-19  Richard Guenther  <rguenther@suse.de>

	* parser.c (CP_LEXER_BUFFER_SIZE): Adjust to assure near
	power-of-two token vector size.

Index: cp/parser.c
===================================================================
*** cp/parser.c	(revision 114767)
--- cp/parser.c	(working copy)
*************** static void cp_parser_initial_pragma
*** 205,211 ****
    (cp_token *);
  
  /* Manifest constants.  */
! #define CP_LEXER_BUFFER_SIZE 10000
  #define CP_SAVED_TOKEN_STACK 5
  
  /* A token type for keywords, as opposed to ordinary identifiers.  */
--- 205,211 ----
    (cp_token *);
  
  /* Manifest constants.  */
! #define CP_LEXER_BUFFER_SIZE (262144/sizeof(cp_token))
  #define CP_SAVED_TOKEN_STACK 5
  
  /* A token type for keywords, as opposed to ordinary identifiers.  */