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ChangeSet@stripped, 2007-08-09 12:25:48-06:00, malff@weblab.(none) +1 -0
Bug#30333 (Performance, expressions lists in the parser)
Before this patch, the parser would execute:
- Select->expr_list.push_front()
- Select->expr_list.pop()
when parsing expressions lists, in the following rules:
- udf_expr_list
- expr_list
- ident_list
This is unnecessary, and introduces overhead due to the memory allocations
performed with Select->expr_list
With this patch, this code has been removed.
The list being parsed is maintained in the parser stack instead.
Also, 'udf_expr_list' has been renamed 'opt_udf_expr_list', since this
production can be empty.
Simplification of the grammar around these lists also reduced the
parser complexity:
/* YYLAST -- Last index in YYTABLE. */
#define YYLAST 43481 --> 43048 [-433]
/* YYNTOKENS -- Number of terminals. */
#define YYNTOKENS 570 --> 570 [0]
/* YYNNTS -- Number of nonterminals. */
#define YYNNTS 674 --> 668 [-6]
/* YYNRULES -- Number of rules. */
#define YYNRULES 2026 --> 2020 [-6]
/* YYNRULES -- Number of states. */
#define YYNSTATES 3672 --> 3666 [-6]
sql/sql_yacc.yy@stripped, 2007-08-09 12:25:46-06:00, malff@weblab.(none) +44 -40
Improved performances when parsing expression lists
diff -Nrup a/sql/sql_yacc.yy b/sql/sql_yacc.yy
--- a/sql/sql_yacc.yy 2007-08-03 10:59:12 -06:00
+++ b/sql/sql_yacc.yy 2007-08-09 12:25:46 -06:00
@@ -1080,7 +1080,7 @@ bool my_yyoverflow(short **a, YYSTYPE **
NUM_literal
%type <item_list>
- expr_list udf_expr_list udf_expr_list2 when_list
+ expr_list opt_udf_expr_list udf_expr_list when_list
ident_list ident_list_arg opt_expr_list
%type <var_type>
@@ -1153,7 +1153,7 @@ bool my_yyoverflow(short **a, YYSTYPE **
select_item_list select_item values_list no_braces
opt_limit_clause delete_limit_clause fields opt_values values
procedure_list procedure_list2 procedure_item
- expr_list2 udf_expr_list3 handler
+ handler
opt_precision opt_ignore opt_column opt_restrict
grant revoke set lock unlock string_list field_options field_option
field_opt_list opt_binary table_lock_list table_lock
@@ -5061,7 +5061,7 @@ simple_expr:
lex->current_select->udf_list.push_front(udf);
#endif
}
- udf_expr_list ')'
+ opt_udf_expr_list ')'
{
LEX *lex= Lex;
#ifdef HAVE_DLOPEN
@@ -5268,27 +5268,23 @@ fulltext_options:
| IN_SYM BOOLEAN_SYM MODE_SYM { $$= FT_BOOL; }
;
-udf_expr_list:
- /* empty */ { $$= NULL; }
- | udf_expr_list2 { $$= $1;}
- ;
-
-udf_expr_list2:
- { Select->expr_list.push_front(new List<Item>); }
- udf_expr_list3
- { $$= Select->expr_list.pop(); }
- ;
+opt_udf_expr_list:
+ /* empty */ { $$= NULL; }
+ | udf_expr_list { $$= $1; }
+ ;
-udf_expr_list3:
- udf_expr
- {
- Select->expr_list.head()->push_back($1);
- }
- | udf_expr_list3 ',' udf_expr
- {
- Select->expr_list.head()->push_back($3);
- }
- ;
+udf_expr_list:
+ udf_expr
+ {
+ $$= new (YYTHD->mem_root) List<Item>;
+ $$->push_back($1);
+ }
+ | udf_expr_list ',' udf_expr
+ {
+ $1->push_back($3);
+ $$= $1;
+ }
+ ;
udf_expr:
remember_name expr remember_end select_alias
@@ -5480,31 +5476,39 @@ cast_type:
;
opt_expr_list:
- /* empty */ { $$= NULL; }
- | expr_list { $$= $1;}
- ;
+ /* empty */ { $$= NULL; }
+ | expr_list { $$= $1;}
+ ;
expr_list:
- { Select->expr_list.push_front(new List<Item>); }
- expr_list2
- { $$= Select->expr_list.pop(); };
-
-expr_list2:
- expr { Select->expr_list.head()->push_back($1); }
- | expr_list2 ',' expr { Select->expr_list.head()->push_back($3); };
+ expr
+ {
+ $$= new (YYTHD->mem_root) List<Item>;
+ $$->push_back($1);
+ }
+ | expr_list ',' expr
+ {
+ $1->push_back($3);
+ $$= $1;
+ }
+ ;
ident_list_arg:
ident_list { $$= $1; }
| '(' ident_list ')' { $$= $2; };
ident_list:
- { Select->expr_list.push_front(new List<Item>); }
- ident_list2
- { $$= Select->expr_list.pop(); };
-
-ident_list2:
- simple_ident { Select->expr_list.head()->push_back($1); }
- | ident_list2 ',' simple_ident { Select->expr_list.head()->push_back($3); };
+ simple_ident
+ {
+ $$= new (YYTHD->mem_root) List<Item>;
+ $$->push_back($1);
+ }
+ | ident_list ',' simple_ident
+ {
+ $1->push_back($3);
+ $$= $1;
+ }
+ ;
opt_expr:
/* empty */ { $$= NULL; }
