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Bug#19194 (Right recursion in parser for CASE causes excessive stack usage,

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limitation)

Note to the reviewer
====================

Warning: reviewing this patch is somewhat involved.
Due to the nature of several issues all affecting the same area,
fixing separately each issue is not practical, since each fix can not be
implemented and tested independently.
In particular, the issues with
- rule recursion
- nested case statements
- forward jump resolution (backpatch list)
are tightly coupled (see below).

Definitions
===========

The expression
  CASE expr
  WHEN expr THEN expr
  WHEN expr THEN expr
  ...
  END
is a "Simple Case Expression".

The expression
  CASE
  WHEN expr THEN expr
  WHEN expr THEN expr
  ...
  END
is a "Searched Case Expression".

The statement
  CASE expr
  WHEN expr THEN stmts
  WHEN expr THEN stmts
  ...
  END CASE
is a "Simple Case Statement".

The statement
  CASE
  WHEN expr THEN stmts
  WHEN expr THEN stmts
  ...
  END CASE
is a "Searched Case Statement".

A "Left Recursive" rule is like
  list:
      element
    | list element
    ;

A "Right Recursive" rule is like
  list:
      element
    | element list
    ;

Left and right recursion produces the same language, the difference only
affects the *order* in which the text is parsed.

In a descendant parser (usually written manually), right recursion works
very well, and is typically implemented with a while loop.
In an ascendant parser (yacc/bison) left recursion works very well,
and is implemented naturally by the parser stack.
In both cases, using the wrong type or recursion is very bad and should be
avoided, as it causes technical issues with the parser implementation.

Before this change
==================

The "Simple Case Expression" and "Searched Case Expression" were both
implemented by the "when_list" and "when_list2" rules, which are left
recursive (ok).

These rules, however, used lex->when_list instead of using the parser stack,
which is more complex that necessary, and potentially dangerous because
of other rules using THD::reset_lex.

The "Simple Case Statement" and "Searched Case Statements" were implemented
by the "sp_case", "sp_whens" and in part by "sp_proc_stmt" rules.
Both cases were right recursive (bad).

The grammar involved was convoluted, and is assumed to be the results of
tweaks to get the code generation to work, but is not what someone would
naturally write.

In addition, using a common rule for both "Simple" and "Searched" case
statements was implemented with sp_head::m_flags |= IN_SIMPLE_CASE,
which is a flag and not a stack, and therefore does not take into account
*nested* case statements. This leads to incorrect generated code, and either
a server crash or an incorrect result.

With regards to the backpatch mechanism, a *different* backpatch list was
created for each jump from "WHEN expr THEN stmt" to "END CASE", which
relied on the grammar to be right recursive.
This is a mis-use of the backpatch list, since this list can resolve
multiple references to the same target at once.

The optimizer algorithm used to detect dead code in the "assembly" SQL
instructions, implemented by sp_head::opt_mark(uint ip), was recursive
in some cases (a conditional jump pointing forward to another conditional
jump).
In case of specially crafted code, like
- a long list of "IF expr THEN stmt END IF"
- a long CASE statement
this would actually cause a server crash with a stack overflow.
In general, having a stack that grows proportionally with user data (the
SQL code given by the client in a CREATE PROCEDURE) is to be avoided.

In debug builds only, creating a SP / SF / Trigger which had a significant
amount of code would spend --literally-- several minutes in sp_head::create,
because of the debug code involved with DBUG_PRINT("info", ("Code %s ...
There are several issues with this code:
- in a CASE with 5 000 WHEN, there are 15 000 instructions generated,
  which create a sting representation of the code which is 500 000 bytes
  long,
- using a String instead of an io stream causes performances to degrade
  to a total server freeze, as time is spent doing realloc of a buffer
  always too short,
- Printing a 500 000 long string in the debug log is too verbose,
- Generating this string even when DBUG_PRINT is off is useless,
- Having code that potentially can affect the server behavior, used with
  #ifdef / #endif is useful in some cases, but is also a bad practice.

After this change
=================

"Case Expressions" (both simple and searched) have been simplified to
not use LEX::when_list, which has been removed.

Considering all the issues affecting case statements, the grammar for these
has been totally re written.

The existing actions, used to generate "assembly" sp_inst* code, have been
preserved but moved in the new grammar, with the following changes:

a) Bison rules are no longer shared between "Simple" and "Searched" case
statements, because a stack instead of a flag is required to handle them.
Nested statements are handled naturally by the parser stack, which by
definition uses the correct rule in the correct context.
Nested statements of the opposite type (simple vs searched) works correctly.
The flag sp_head::IN_SIMPLE_CASE is no longer used.
This is a step towards resolution of WL#2999, which correctly identified
that temporary parsing flags do not belong to sp_head.
The code in the action is shared by mean of the case_stmt_action_xxx()
helpers.

b) The backpatch mechanism, used to resolve forward jumps in the generated
code, has been changed to:
- create a label for the instruction following 'END CASE',
- register each jump at the end of a "WHEN expr THEN stmt" in a *unique*
  backpatch list associated with the 'END CASE' label
- resolve all the forward jumps for this label at once.

In addition, the code involving backpatch has been commented, so that a
reader can now understand by reading matching "Registering" and "Resolving"
comments how the forward jumps are resolved and what target they resolve to,
as this is far from evident when reading the code alone.

The implementation of sp_head::opt_mark() has been revised to avoid
recursive calls from jump instructions, and instead add the jump location
to the list of paths to explore during the flow analysis of the instruction
graph, with a call to sp_head::add_mark_lead().
In addition, the flow analysis will stop if an instruction has already
been marked as reachable, which the previous code failed to do in the
recursive case.
sp_head::opt_mark() is now private, to prevent new calls to this method from
being introduced.

The debug code present in sp_head::create() has been removed.
Considering that SHOW PROCEDURE CODE is also available in debug builds,
and can be used anytime regardless of the trace level, as opposed to
"CREATE PROCEDURE" time and only if the trace was on,
removing the code actually makes debugging easier (usable trace).

Tests have been written to cover the parser overflow (big CASE),
and to cover nested CASE statements.


mysql-test/r/sp-code.result:
  Test cases for nested CASE statements.
mysql-test/t/sp-code.test:
  Test cases for nested CASE statements.
sql/sp_head.cc:
  Re factored opt_mark() to avoid recursion, clean up.
sql/sp_head.h:
  Re factored opt_mark() to avoid recursion, clean up.
sql/sql_lex.cc:
  Removed when_list.
sql/sql_lex.h:
  Removed when_list.
sql/sql_yacc.yy:
  Minor clean up for case expressions,
  Major re write for case statements (Bug#19194).
mysql-test/r/sp_stress_case.result:
  New test for massive CASE statements.
mysql-test/t/sp_stress_case.sh:
  New test for massive CASE statements.
mysql-test/t/sp_stress_case.test:
  New test for massive CASE statements.
This commit is contained in:
unknown 2006-11-17 12:14:29 -07:00
parent 1c1fd2a46e
commit 476eaae84d
10 changed files with 1138 additions and 171 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

415
mysql-test/r/sp-code.result
View file

@ -199,6 +199,421 @@ Pos Instruction
44 jump 14
45 stmt 9 "drop temporary table sudoku_work, sud..."
drop procedure sudoku_solve;
DROP PROCEDURE IF EXISTS proc_19194_simple;
DROP PROCEDURE IF EXISTS proc_19194_searched;
DROP PROCEDURE IF EXISTS proc_19194_nested_1;
DROP PROCEDURE IF EXISTS proc_19194_nested_2;
DROP PROCEDURE IF EXISTS proc_19194_nested_3;
DROP PROCEDURE IF EXISTS proc_19194_nested_4;
CREATE PROCEDURE proc_19194_simple(i int)
BEGIN
DECLARE str CHAR(10);
CASE i
WHEN 1 THEN SET str="1";
WHEN 2 THEN SET str="2";
WHEN 3 THEN SET str="3";
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
CREATE PROCEDURE proc_19194_searched(i int)
BEGIN
DECLARE str CHAR(10);
CASE
WHEN i=1 THEN SET str="1";
WHEN i=2 THEN SET str="2";
WHEN i=3 THEN SET str="3";
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
CREATE PROCEDURE proc_19194_nested_1(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE i
WHEN 10 THEN SET str_i="10";
WHEN 20 THEN
BEGIN
set str_i="20";
CASE
WHEN j=1 THEN SET str_j="1";
WHEN j=2 THEN SET str_j="2";
WHEN j=3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN 30 THEN SET str_i="30";
WHEN 40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
CREATE PROCEDURE proc_19194_nested_2(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE
WHEN i=10 THEN SET str_i="10";
WHEN i=20 THEN
BEGIN
set str_i="20";
CASE j
WHEN 1 THEN SET str_j="1";
WHEN 2 THEN SET str_j="2";
WHEN 3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN i=30 THEN SET str_i="30";
WHEN i=40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
CREATE PROCEDURE proc_19194_nested_3(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE i
WHEN 10 THEN SET str_i="10";
WHEN 20 THEN
BEGIN
set str_i="20";
CASE j
WHEN 1 THEN SET str_j="1";
WHEN 2 THEN SET str_j="2";
WHEN 3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN 30 THEN SET str_i="30";
WHEN 40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
CREATE PROCEDURE proc_19194_nested_4(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE
WHEN i=10 THEN SET str_i="10";
WHEN i=20 THEN
BEGIN
set str_i="20";
CASE
WHEN j=1 THEN SET str_j="1";
WHEN j=2 THEN SET str_j="2";
WHEN j=3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN i=30 THEN SET str_i="30";
WHEN i=40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
SHOW PROCEDURE CODE proc_19194_simple;
Pos Instruction
0 set str@1 NULL
1 set_case_expr (12) 0 i@0
2 jump_if_not 5(12) (case_expr@0 = 1)
3 set str@1 _latin1'1'
4 jump 12
5 jump_if_not 8(12) (case_expr@0 = 2)
6 set str@1 _latin1'2'
7 jump 12
8 jump_if_not 11(12) (case_expr@0 = 3)
9 set str@1 _latin1'3'
10 jump 12
11 set str@1 _latin1'unknown'
12 stmt 0 "SELECT str"
SHOW PROCEDURE CODE proc_19194_searched;
Pos Instruction
0 set str@1 NULL
1 jump_if_not 4(11) (i@0 = 1)
2 set str@1 _latin1'1'
3 jump 11
4 jump_if_not 7(11) (i@0 = 2)
5 set str@1 _latin1'2'
6 jump 11
7 jump_if_not 10(11) (i@0 = 3)
8 set str@1 _latin1'3'
9 jump 11
10 set str@1 _latin1'unknown'
11 stmt 0 "SELECT str"
SHOW PROCEDURE CODE proc_19194_nested_1;
Pos Instruction
0 set str_i@2 NULL
1 set str_j@3 NULL
2 set_case_expr (27) 0 i@0
3 jump_if_not 6(27) (case_expr@0 = 10)
4 set str_i@2 _latin1'10'
5 jump 27
6 jump_if_not 20(27) (case_expr@0 = 20)
7 set str_i@2 _latin1'20'
8 jump_if_not 11(18) (j@1 = 1)
9 set str_j@3 _latin1'1'
10 jump 18
11 jump_if_not 14(18) (j@1 = 2)
12 set str_j@3 _latin1'2'
13 jump 18
14 jump_if_not 17(18) (j@1 = 3)
15 set str_j@3 _latin1'3'
16 jump 18
17 set str_j@3 _latin1'unknown'
18 stmt 0 "select "i was 20""
19 jump 27
20 jump_if_not 23(27) (case_expr@0 = 30)
21 set str_i@2 _latin1'30'
22 jump 27
23 jump_if_not 26(27) (case_expr@0 = 40)
24 set str_i@2 _latin1'40'
25 jump 27
26 set str_i@2 _latin1'unknown'
27 stmt 0 "SELECT str_i, str_j"
SHOW PROCEDURE CODE proc_19194_nested_2;
Pos Instruction
0 set str_i@2 NULL
1 set str_j@3 NULL
2 jump_if_not 5(27) (i@0 = 10)
3 set str_i@2 _latin1'10'
4 jump 27
5 jump_if_not 20(27) (i@0 = 20)
6 set str_i@2 _latin1'20'
7 set_case_expr (18) 0 j@1
8 jump_if_not 11(18) (case_expr@0 = 1)
9 set str_j@3 _latin1'1'
10 jump 18
11 jump_if_not 14(18) (case_expr@0 = 2)
12 set str_j@3 _latin1'2'
13 jump 18
14 jump_if_not 17(18) (case_expr@0 = 3)
15 set str_j@3 _latin1'3'
16 jump 18
17 set str_j@3 _latin1'unknown'
18 stmt 0 "select "i was 20""
19 jump 27
20 jump_if_not 23(27) (i@0 = 30)
21 set str_i@2 _latin1'30'
22 jump 27
23 jump_if_not 26(27) (i@0 = 40)
24 set str_i@2 _latin1'40'
25 jump 27
26 set str_i@2 _latin1'unknown'
27 stmt 0 "SELECT str_i, str_j"
SHOW PROCEDURE CODE proc_19194_nested_3;
Pos Instruction
0 set str_i@2 NULL
1 set str_j@3 NULL
2 set_case_expr (28) 0 i@0
3 jump_if_not 6(28) (case_expr@0 = 10)
4 set str_i@2 _latin1'10'
5 jump 28
6 jump_if_not 21(28) (case_expr@0 = 20)
7 set str_i@2 _latin1'20'
8 set_case_expr (19) 1 j@1
9 jump_if_not 12(19) (case_expr@1 = 1)
10 set str_j@3 _latin1'1'
11 jump 19
12 jump_if_not 15(19) (case_expr@1 = 2)
13 set str_j@3 _latin1'2'
14 jump 19
15 jump_if_not 18(19) (case_expr@1 = 3)
16 set str_j@3 _latin1'3'
17 jump 19
18 set str_j@3 _latin1'unknown'
19 stmt 0 "select "i was 20""
20 jump 28
21 jump_if_not 24(28) (case_expr@0 = 30)
22 set str_i@2 _latin1'30'
23 jump 28
24 jump_if_not 27(28) (case_expr@0 = 40)
25 set str_i@2 _latin1'40'
26 jump 28
27 set str_i@2 _latin1'unknown'
28 stmt 0 "SELECT str_i, str_j"
SHOW PROCEDURE CODE proc_19194_nested_4;
Pos Instruction
0 set str_i@2 NULL
1 set str_j@3 NULL
2 jump_if_not 5(26) (i@0 = 10)
3 set str_i@2 _latin1'10'
4 jump 26
5 jump_if_not 19(26) (i@0 = 20)
6 set str_i@2 _latin1'20'
7 jump_if_not 10(17) (j@1 = 1)
8 set str_j@3 _latin1'1'
9 jump 17
10 jump_if_not 13(17) (j@1 = 2)
11 set str_j@3 _latin1'2'
12 jump 17
13 jump_if_not 16(17) (j@1 = 3)
14 set str_j@3 _latin1'3'
15 jump 17
16 set str_j@3 _latin1'unknown'
17 stmt 0 "select "i was 20""
18 jump 26
19 jump_if_not 22(26) (i@0 = 30)
20 set str_i@2 _latin1'30'
21 jump 26
22 jump_if_not 25(26) (i@0 = 40)
23 set str_i@2 _latin1'40'
24 jump 26
25 set str_i@2 _latin1'unknown'
26 stmt 0 "SELECT str_i, str_j"
CALL proc_19194_nested_1(10, 1);
str_i str_j
10 NULL
CALL proc_19194_nested_1(25, 1);
str_i str_j
unknown NULL
CALL proc_19194_nested_1(20, 1);
i was 20
i was 20
str_i str_j
20 1
CALL proc_19194_nested_1(20, 2);
i was 20
i was 20
str_i str_j
20 2
CALL proc_19194_nested_1(20, 3);
i was 20
i was 20
str_i str_j
20 3
CALL proc_19194_nested_1(20, 4);
i was 20
i was 20
str_i str_j
20 unknown
CALL proc_19194_nested_1(30, 1);
str_i str_j
30 NULL
CALL proc_19194_nested_1(40, 1);
str_i str_j
40 NULL
CALL proc_19194_nested_1(0, 0);
str_i str_j
unknown NULL
CALL proc_19194_nested_2(10, 1);
str_i str_j
10 NULL
CALL proc_19194_nested_2(25, 1);
str_i str_j
unknown NULL
CALL proc_19194_nested_2(20, 1);
i was 20
i was 20
str_i str_j
20 1
CALL proc_19194_nested_2(20, 2);
i was 20
i was 20
str_i str_j
20 2
CALL proc_19194_nested_2(20, 3);
i was 20
i was 20
str_i str_j
20 3
CALL proc_19194_nested_2(20, 4);
i was 20
i was 20
str_i str_j
20 unknown
CALL proc_19194_nested_2(30, 1);
str_i str_j
30 NULL
CALL proc_19194_nested_2(40, 1);
str_i str_j
40 NULL
CALL proc_19194_nested_2(0, 0);
str_i str_j
unknown NULL
CALL proc_19194_nested_3(10, 1);
str_i str_j
10 NULL
CALL proc_19194_nested_3(25, 1);
str_i str_j
unknown NULL
CALL proc_19194_nested_3(20, 1);
i was 20
i was 20
str_i str_j
20 1
CALL proc_19194_nested_3(20, 2);
i was 20
i was 20
str_i str_j
20 2
CALL proc_19194_nested_3(20, 3);
i was 20
i was 20
str_i str_j
20 3
CALL proc_19194_nested_3(20, 4);
i was 20
i was 20
str_i str_j
20 unknown
CALL proc_19194_nested_3(30, 1);
str_i str_j
30 NULL
CALL proc_19194_nested_3(40, 1);
str_i str_j
40 NULL
CALL proc_19194_nested_3(0, 0);
str_i str_j
unknown NULL
CALL proc_19194_nested_4(10, 1);
str_i str_j
10 NULL
CALL proc_19194_nested_4(25, 1);
str_i str_j
unknown NULL
CALL proc_19194_nested_4(20, 1);
i was 20
i was 20
str_i str_j
20 1
CALL proc_19194_nested_4(20, 2);
i was 20
i was 20
str_i str_j
20 2
CALL proc_19194_nested_4(20, 3);
i was 20
i was 20
str_i str_j
20 3
CALL proc_19194_nested_4(20, 4);
i was 20
i was 20
str_i str_j
20 unknown
CALL proc_19194_nested_4(30, 1);
str_i str_j
30 NULL
CALL proc_19194_nested_4(40, 1);
str_i str_j
40 NULL
CALL proc_19194_nested_4(0, 0);
str_i str_j
unknown NULL
DROP PROCEDURE proc_19194_simple;
DROP PROCEDURE proc_19194_searched;
DROP PROCEDURE proc_19194_nested_1;
DROP PROCEDURE proc_19194_nested_2;
DROP PROCEDURE proc_19194_nested_3;
DROP PROCEDURE proc_19194_nested_4;
DROP PROCEDURE IF EXISTS p1;
CREATE PROCEDURE p1() CREATE INDEX idx ON t1 (c1);
SHOW PROCEDURE CODE p1;

42
mysql-test/r/sp_stress_case.result Normal file
View file

@ -0,0 +1,42 @@
DROP PROCEDURE IF EXISTS bug_19194_a;
DROP PROCEDURE IF EXISTS bug_19194_b;
'Silently creating PROCEDURE bug_19194_a'
'Silently creating PROCEDURE bug_19194_b'
CALL bug_19194_a(1);
str
1
CALL bug_19194_a(2);
str
2
CALL bug_19194_a(1000);
str
1000
CALL bug_19194_a(4998);
str
4998
CALL bug_19194_a(4999);
str
4999
CALL bug_19194_a(9999);
str
unknown
CALL bug_19194_b(1);
str
1
CALL bug_19194_b(2);
str
2
CALL bug_19194_b(1000);
str
1000
CALL bug_19194_b(4998);
str
4998
CALL bug_19194_b(4999);
str
4999
CALL bug_19194_b(9999);
str
unknown
DROP PROCEDURE bug_19194_a;
DROP PROCEDURE bug_19194_b;

235
mysql-test/t/sp-code.test
View file

@ -191,6 +191,241 @@ show procedure code sudoku_solve;
drop procedure sudoku_solve;
#
# Bug#19194 (Right recursion in parser for CASE causes excessive stack
# usage, limitation)
# This bug also exposed a flaw in the generated code with nested case
# statements
#
--disable_warnings
DROP PROCEDURE IF EXISTS proc_19194_simple;
DROP PROCEDURE IF EXISTS proc_19194_searched;
DROP PROCEDURE IF EXISTS proc_19194_nested_1;
DROP PROCEDURE IF EXISTS proc_19194_nested_2;
DROP PROCEDURE IF EXISTS proc_19194_nested_3;
DROP PROCEDURE IF EXISTS proc_19194_nested_4;
--enable_warnings
delimiter |;
CREATE PROCEDURE proc_19194_simple(i int)
BEGIN
DECLARE str CHAR(10);
CASE i
WHEN 1 THEN SET str="1";
WHEN 2 THEN SET str="2";
WHEN 3 THEN SET str="3";
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
CREATE PROCEDURE proc_19194_searched(i int)
BEGIN
DECLARE str CHAR(10);
CASE
WHEN i=1 THEN SET str="1";
WHEN i=2 THEN SET str="2";
WHEN i=3 THEN SET str="3";
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
# Outer SIMPLE case, inner SEARCHED case
CREATE PROCEDURE proc_19194_nested_1(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE i
WHEN 10 THEN SET str_i="10";
WHEN 20 THEN
BEGIN
set str_i="20";
CASE
WHEN j=1 THEN SET str_j="1";
WHEN j=2 THEN SET str_j="2";
WHEN j=3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN 30 THEN SET str_i="30";
WHEN 40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
# Outer SEARCHED case, inner SIMPLE case
CREATE PROCEDURE proc_19194_nested_2(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE
WHEN i=10 THEN SET str_i="10";
WHEN i=20 THEN
BEGIN
set str_i="20";
CASE j
WHEN 1 THEN SET str_j="1";
WHEN 2 THEN SET str_j="2";
WHEN 3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN i=30 THEN SET str_i="30";
WHEN i=40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
# Outer SIMPLE case, inner SIMPLE case
CREATE PROCEDURE proc_19194_nested_3(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE i
WHEN 10 THEN SET str_i="10";
WHEN 20 THEN
BEGIN
set str_i="20";
CASE j
WHEN 1 THEN SET str_j="1";
WHEN 2 THEN SET str_j="2";
WHEN 3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN 30 THEN SET str_i="30";
WHEN 40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
# Outer SEARCHED case, inner SEARCHED case
CREATE PROCEDURE proc_19194_nested_4(i int, j int)
BEGIN
DECLARE str_i CHAR(10);
DECLARE str_j CHAR(10);
CASE
WHEN i=10 THEN SET str_i="10";
WHEN i=20 THEN
BEGIN
set str_i="20";
CASE
WHEN j=1 THEN SET str_j="1";
WHEN j=2 THEN SET str_j="2";
WHEN j=3 THEN SET str_j="3";
ELSE SET str_j="unknown";
END CASE;
select "i was 20";
END;
WHEN i=30 THEN SET str_i="30";
WHEN i=40 THEN SET str_i="40";
ELSE SET str_i="unknown";
END CASE;
SELECT str_i, str_j;
END|
delimiter ;|
SHOW PROCEDURE CODE proc_19194_simple;
SHOW PROCEDURE CODE proc_19194_searched;
SHOW PROCEDURE CODE proc_19194_nested_1;
SHOW PROCEDURE CODE proc_19194_nested_2;
SHOW PROCEDURE CODE proc_19194_nested_3;
SHOW PROCEDURE CODE proc_19194_nested_4;
CALL proc_19194_nested_1(10, 1);
#
# Before 19194, the generated code was:
# 20 jump_if_not 23(27) 30
# 21 set str_i@2 _latin1'30'
# As opposed to the expected:
# 20 jump_if_not 23(27) (case_expr@0 = 30)
# 21 set str_i@2 _latin1'30'
#
# and as a result, this call returned "30",
# because the expression 30 is always true,
# masking the case 40, case 0 and the else.
#
CALL proc_19194_nested_1(25, 1);
CALL proc_19194_nested_1(20, 1);
CALL proc_19194_nested_1(20, 2);
CALL proc_19194_nested_1(20, 3);
CALL proc_19194_nested_1(20, 4);
CALL proc_19194_nested_1(30, 1);
CALL proc_19194_nested_1(40, 1);
CALL proc_19194_nested_1(0, 0);
CALL proc_19194_nested_2(10, 1);
#
# Before 19194, the generated code was:
# 20 jump_if_not 23(27) (case_expr@0 = (i@0 = 30))
# 21 set str_i@2 _latin1'30'
# As opposed to the expected:
# 20 jump_if_not 23(27) (i@0 = 30)
# 21 set str_i@2 _latin1'30'
# and as a result, this call crashed the server, because there is no
# such variable as "case_expr@0".
#
CALL proc_19194_nested_2(25, 1);
CALL proc_19194_nested_2(20, 1);
CALL proc_19194_nested_2(20, 2);
CALL proc_19194_nested_2(20, 3);
CALL proc_19194_nested_2(20, 4);
CALL proc_19194_nested_2(30, 1);
CALL proc_19194_nested_2(40, 1);
CALL proc_19194_nested_2(0, 0);
CALL proc_19194_nested_3(10, 1);
CALL proc_19194_nested_3(25, 1);
CALL proc_19194_nested_3(20, 1);
CALL proc_19194_nested_3(20, 2);
CALL proc_19194_nested_3(20, 3);
CALL proc_19194_nested_3(20, 4);
CALL proc_19194_nested_3(30, 1);
CALL proc_19194_nested_3(40, 1);
CALL proc_19194_nested_3(0, 0);
CALL proc_19194_nested_4(10, 1);
CALL proc_19194_nested_4(25, 1);
CALL proc_19194_nested_4(20, 1);
CALL proc_19194_nested_4(20, 2);
CALL proc_19194_nested_4(20, 3);
CALL proc_19194_nested_4(20, 4);
CALL proc_19194_nested_4(30, 1);
CALL proc_19194_nested_4(40, 1);
CALL proc_19194_nested_4(0, 0);
DROP PROCEDURE proc_19194_simple;
DROP PROCEDURE proc_19194_searched;
DROP PROCEDURE proc_19194_nested_1;
DROP PROCEDURE proc_19194_nested_2;
DROP PROCEDURE proc_19194_nested_3;
DROP PROCEDURE proc_19194_nested_4;
#
# Bug#19207: Final parenthesis omitted for CREATE INDEX in Stored

68
mysql-test/t/sp_stress_case.sh Executable file
View file

@ -0,0 +1,68 @@
#!/bin/sh
#
# Bug#19194 (Right recursion in parser for CASE causes excessive stack
# usage, limitation)
#
# Because the code for the CASE statement is so massive,
# checking in an already generated .test is not practical,
# due to it's size (10 000 lines or 356 000 bytes).
#
# Patches are sent by email, which introduce size limitations.
#
# As a result, code is generated dynamically here.
# This script takes no argument, and generates code in stdout.
#
cat <<EOF
echo 'Silently creating PROCEDURE bug_19194_a';
--disable_query_log
delimiter |;
CREATE PROCEDURE bug_19194_a(i int)
BEGIN
DECLARE str CHAR(10);
CASE i
EOF
count=1;
while true; do
echo " WHEN $count THEN SET str=\"$count\";"
count=`expr $count + 1`
test $count -gt 5000 && break
done
cat <<EOF
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
delimiter ;|
--enable_query_log
EOF
cat <<EOF
echo 'Silently creating PROCEDURE bug_19194_b';
--disable_query_log
delimiter |;
CREATE PROCEDURE bug_19194_b(i int)
BEGIN
DECLARE str CHAR(10);
CASE
EOF
count=1;
while true; do
echo " WHEN i=$count THEN SET str=\"$count\";"
count=`expr $count + 1`
test $count -gt 5000 && break
done
cat <<EOF
ELSE SET str="unknown";
END CASE;
SELECT str;
END|
delimiter ;|
--enable_query_log
EOF

35
mysql-test/t/sp_stress_case.test Normal file
View file

@ -0,0 +1,35 @@
# The production code tested is not platform specific,
# but /bin/sh is needed to run the test case.
--source include/not_windows.inc
#
# Bug#19194 (Right recursion in parser for CASE causes excessive stack
# usage, limitation)
#
--disable_warnings
DROP PROCEDURE IF EXISTS bug_19194_a;
DROP PROCEDURE IF EXISTS bug_19194_b;
--enable_warnings
--exec $MYSQL_TEST_DIR/t/sp_stress_case.sh | $MYSQL_TEST 2>&1
CALL bug_19194_a(1);
CALL bug_19194_a(2);
CALL bug_19194_a(1000);
CALL bug_19194_a(4998);
CALL bug_19194_a(4999);
CALL bug_19194_a(9999);
CALL bug_19194_b(1);
CALL bug_19194_b(2);
CALL bug_19194_b(1000);
CALL bug_19194_b(4998);
CALL bug_19194_b(4999);
CALL bug_19194_b(9999);
DROP PROCEDURE bug_19194_a;
DROP PROCEDURE bug_19194_b;

100
sql/sp_head.cc
View file

@ -603,27 +603,6 @@ sp_head::create(THD *thd)
DBUG_PRINT("info", ("type: %d name: %s params: %s body: %s",
m_type, m_name.str, m_params.str, m_body.str));
#ifndef DBUG_OFF
optimize();
{
String s;
sp_instr *i;
uint ip= 0;
while ((i = get_instr(ip)))
{
char buf[8];
sprintf(buf, "%4u: ", ip);
s.append(buf);
i->print(&s);
s.append('\n');
ip+= 1;
}
s.append('\0');
DBUG_PRINT("info", ("Code %s\n%s", m_qname.str, s.ptr()));
}
#endif
if (m_type == TYPE_ENUM_FUNCTION)
ret= sp_create_function(thd, this);
else
@ -2172,7 +2151,7 @@ sp_head::show_create_function(THD *thd)
This is the main mark and move loop; it relies on the following methods
in sp_instr and its subclasses:
opt_mark() Mark instruction as reachable (will recurse for jumps)
opt_mark() Mark instruction as reachable
opt_shortcut_jump() Shortcut jumps to the final destination;
used by opt_mark().
opt_move() Update moved instruction
@ -2185,7 +2164,7 @@ void sp_head::optimize()
sp_instr *i;
uint src, dst;
opt_mark(0);
opt_mark();
bp.empty();
src= dst= 0;
@ -2219,13 +2198,50 @@ void sp_head::optimize()
bp.empty();
}
void
sp_head::opt_mark(uint ip)
void sp_head::add_mark_lead(uint ip, List<sp_instr> *leads)
{
sp_instr *i;
sp_instr *i= get_instr(ip);
while ((i= get_instr(ip)) && !i->marked)
ip= i->opt_mark(this);
if (i && ! i->marked)
leads->push_front(i);
}
void
sp_head::opt_mark()
{
uint ip;
sp_instr *i;
List<sp_instr> leads;
/*
Forward flow analysis algorithm in the instruction graph:
- first, add the entry point in the graph (the first instruction) to the
'leads' list of paths to explore.
- while there are still leads to explore:
- pick one lead, and follow the path forward. Mark instruction reached.
Stop only if the end of the routine is reached, or the path converge
to code already explored (marked).
- while following a path, collect in the 'leads' list any fork to
another path (caused by conditional jumps instructions), so that these
paths can be explored as well.
*/
/* Add the entry point */
i= get_instr(0);
leads.push_front(i);
/* For each path of code ... */
while (leads.elements != 0)
{
i= leads.pop();
/* Mark the entire path, collecting new leads. */
while (i && ! i->marked)
{
ip= i->opt_mark(this, & leads);
i= get_instr(ip);
}
}
}
@ -2618,7 +2634,7 @@ sp_instr_jump::print(String *str)
}
uint
sp_instr_jump::opt_mark(sp_head *sp)
sp_instr_jump::opt_mark(sp_head *sp, List<sp_instr> *leads)
{
m_dest= opt_shortcut_jump(sp, this);
if (m_dest != m_ip+1) /* Jumping to following instruction? */
@ -2712,7 +2728,7 @@ sp_instr_jump_if_not::print(String *str)
uint
sp_instr_jump_if_not::opt_mark(sp_head *sp)
sp_instr_jump_if_not::opt_mark(sp_head *sp, List<sp_instr> *leads)
{
sp_instr *i;
@ -2722,13 +2738,13 @@ sp_instr_jump_if_not::opt_mark(sp_head *sp)
m_dest= i->opt_shortcut_jump(sp, this);
m_optdest= sp->get_instr(m_dest);
}
sp->opt_mark(m_dest);
sp->add_mark_lead(m_dest, leads);
if ((i= sp->get_instr(m_cont_dest)))
{
m_cont_dest= i->opt_shortcut_jump(sp, this);
m_cont_optdest= sp->get_instr(m_cont_dest);
}
sp->opt_mark(m_cont_dest);
sp->add_mark_lead(m_cont_dest, leads);
return m_ip+1;
}
@ -2849,7 +2865,7 @@ sp_instr_hpush_jump::print(String *str)
uint
sp_instr_hpush_jump::opt_mark(sp_head *sp)
sp_instr_hpush_jump::opt_mark(sp_head *sp, List<sp_instr> *leads)
{
sp_instr *i;
@ -2859,7 +2875,7 @@ sp_instr_hpush_jump::opt_mark(sp_head *sp)
m_dest= i->opt_shortcut_jump(sp, this);
m_optdest= sp->get_instr(m_dest);
}
sp->opt_mark(m_dest);
sp->add_mark_lead(m_dest, leads);
return m_ip+1;
}
@ -2924,15 +2940,13 @@ sp_instr_hreturn::print(String *str)
uint
sp_instr_hreturn::opt_mark(sp_head *sp)
sp_instr_hreturn::opt_mark(sp_head *sp, List<sp_instr> *leads)
{
if (m_dest)
return sp_instr_jump::opt_mark(sp);
else
{
marked= 1;
return UINT_MAX;
}
return sp_instr_jump::opt_mark(sp, leads);
marked= 1;
return UINT_MAX;
}
@ -3275,7 +3289,7 @@ sp_instr_set_case_expr::print(String *str)
}
uint
sp_instr_set_case_expr::opt_mark(sp_head *sp)
sp_instr_set_case_expr::opt_mark(sp_head *sp, List<sp_instr> *leads)
{
sp_instr *i;
@ -3285,7 +3299,7 @@ sp_instr_set_case_expr::opt_mark(sp_head *sp)
m_cont_dest= i->opt_shortcut_jump(sp, this);
m_cont_optdest= sp->get_instr(m_cont_dest);
}
sp->opt_mark(m_cont_dest);
sp->add_mark_lead(m_cont_dest, leads);
return m_ip+1;
}

39
sql/sp_head.h
View file

@ -302,8 +302,19 @@ public:
void restore_thd_mem_root(THD *thd);
/**
Optimize the code.
*/
void optimize();
void opt_mark(uint ip);
/**
Helper used during flow analysis during code optimization.
See the implementation of <code>opt_mark()</code>.
@param ip the instruction to add to the leads list
@param leads the list of remaining paths to explore in the graph that
represents the code, during flow analysis.
*/
void add_mark_lead(uint ip, List<sp_instr> *leads);
void recursion_level_error(THD *thd);
@ -393,6 +404,12 @@ private:
bool
execute(THD *thd);
/**
Perform a forward flow analysis in the generated code.
Mark reachable instructions, for the optimizer.
*/
void opt_mark();
/*
Merge the list of tables used by query into the multi-set of tables used
by routine.
@ -460,10 +477,10 @@ public:
/*
Mark this instruction as reachable during optimization and return the
index to the next instruction. Jump instruction will mark their
destination too recursively.
index to the next instruction. Jump instruction will add their
destination to the leads list.
*/
virtual uint opt_mark(sp_head *sp)
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads)
{
marked= 1;
return m_ip+1;
@ -735,7 +752,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp);
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads);
virtual uint opt_shortcut_jump(sp_head *sp, sp_instr *start);
@ -785,7 +802,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp);
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads);
/* Override sp_instr_jump's shortcut; we stop here */
virtual uint opt_shortcut_jump(sp_head *sp, sp_instr *start)
@ -831,7 +848,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp)
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads)
{
marked= 1;
return UINT_MAX;
@ -868,7 +885,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp);
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads);
/* Override sp_instr_jump's shortcut; we stop here. */
virtual uint opt_shortcut_jump(sp_head *sp, sp_instr *start)
@ -933,7 +950,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp);
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads);
private:
@ -1103,7 +1120,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp)
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads)
{
marked= 1;
return UINT_MAX;
@ -1136,7 +1153,7 @@ public:
virtual void print(String *str);
virtual uint opt_mark(sp_head *sp);
virtual uint opt_mark(sp_head *sp, List<sp_instr> *leads);
virtual void opt_move(uint dst, List<sp_instr> *ibp);

1
sql/sql_lex.cc
View file

@ -1163,7 +1163,6 @@ void st_select_lex::init_select()
options= 0;
sql_cache= SQL_CACHE_UNSPECIFIED;
braces= 0;
when_list.empty();
expr_list.empty();
interval_list.empty();
use_index.empty();

1
sql/sql_lex.h
View file

@ -518,7 +518,6 @@ public:
SQL_LIST order_list; /* ORDER clause */
List<List_item> expr_list;
List<List_item> when_list; /* WHEN clause (expression) */
SQL_LIST *gorder_list;
Item *select_limit, *offset_limit; /* LIMIT clause parameters */
// Arrays of pointers to top elements of all_fields list

373
sql/sql_yacc.yy
View file

@ -96,6 +96,146 @@ void turn_parser_debug_on()
}
#endif
/**
Helper action for a case statement (entering the CASE).
This helper is used for both 'simple' and 'searched' cases.
@param lex the parser lex context
*/
void case_stmt_action_case(LEX *lex)
{
lex->sphead->new_cont_backpatch(NULL);
/*
BACKPATCH: Creating target label for the jump to
"case_stmt_action_end_case"
*/
lex->spcont->push_label((char *)"", lex->sphead->instructions());
}
/**
Helper action for a case expression statement (the expr in 'CASE expr').
This helper is used for 'searched' cases only.
@param lex the parser lex context
@param expr the parsed expression
@return 0 on success
*/
int case_stmt_action_expr(LEX *lex, Item* expr)
{
sp_head *sp= lex->sphead;
sp_pcontext *parsing_ctx= lex->spcont;
int case_expr_id= parsing_ctx->register_case_expr();
sp_instr_set_case_expr *i;
if (parsing_ctx->push_case_expr_id(case_expr_id))
return 1;
i= new sp_instr_set_case_expr(sp->instructions(),
parsing_ctx, case_expr_id, expr, lex);
sp->add_cont_backpatch(i);
sp->add_instr(i);
return 0;
}
/**
Helper action for a case when condition.
This helper is used for both 'simple' and 'searched' cases.
@param lex the parser lex context
@param when the parsed expression for the WHEN clause
@param simple true for simple cases, false for searched cases
*/
void case_stmt_action_when(LEX *lex, Item *when, bool simple)
{
sp_head *sp= lex->sphead;
sp_pcontext *ctx= lex->spcont;
uint ip= sp->instructions();
sp_instr_jump_if_not *i;
Item_case_expr *var;
Item *expr;
if (simple)
{
var= new Item_case_expr(ctx->get_current_case_expr_id());
#ifndef DBUG_OFF
if (var)
{
var->m_sp= sp;
}
#endif
expr= new Item_func_eq(var, when);
i= new sp_instr_jump_if_not(ip, ctx, expr, lex);
}
else
i= new sp_instr_jump_if_not(ip, ctx, when, lex);
/*
BACKPATCH: Registering forward jump from
"case_stmt_action_when" to "case_stmt_action_then"
*/
sp->push_backpatch(i, ctx->push_label((char *)"", 0));
sp->add_cont_backpatch(i);
sp->add_instr(i);
}
/**
Helper action for a case then statements.
This helper is used for both 'simple' and 'searched' cases.
@param lex the parser lex context
*/
void case_stmt_action_then(LEX *lex)
{
sp_head *sp= lex->sphead;
sp_pcontext *ctx= lex->spcont;
uint ip= sp->instructions();
sp_instr_jump *i = new sp_instr_jump(ip, ctx);
sp->add_instr(i);
/*
BACKPATCH: Resolving forward jump from
"case_stmt_action_when" to "case_stmt_action_then"
*/
sp->backpatch(ctx->pop_label());
/*
BACKPATCH: Registering forward jump from
"case_stmt_action_when" to "case_stmt_action_end_case"
*/
sp->push_backpatch(i, ctx->last_label());
}
/**
Helper action for an end case.
This helper is used for both 'simple' and 'searched' cases.
@param lex the parser lex context
@param simple true for simple cases, false for searched cases
*/
void case_stmt_action_end_case(LEX *lex, bool simple)
{
/*
BACKPATCH: Resolving forward jump from
"case_stmt_action_then" to "case_stmt_action_end_case"
*/
lex->sphead->backpatch(lex->spcont->pop_label());
if (simple)
lex->spcont->pop_case_expr_id();
lex->sphead->do_cont_backpatch();
}
%}
%union {
int num;
@ -832,7 +972,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
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
when_list2 expr_list2 udf_expr_list3 handler
expr_list2 udf_expr_list3 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
@ -860,6 +1000,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
view_algorithm view_or_trigger_or_sp view_or_trigger_or_sp_tail
view_suid view_tail view_list_opt view_list view_select
view_check_option trigger_tail sp_tail
case_stmt_specification simple_case_stmt searched_case_stmt
END_OF_INPUT
%type <NONE> call sp_proc_stmts sp_proc_stmts1 sp_proc_stmt
@ -1995,43 +2136,7 @@ sp_proc_stmt:
{ Lex->sphead->new_cont_backpatch(NULL); }
sp_if END IF
{ Lex->sphead->do_cont_backpatch(); }
| CASE_SYM WHEN_SYM
{
Lex->sphead->m_flags&= ~sp_head::IN_SIMPLE_CASE;
Lex->sphead->new_cont_backpatch(NULL);
}
sp_case END CASE_SYM { Lex->sphead->do_cont_backpatch(); }
| CASE_SYM
{
Lex->sphead->reset_lex(YYTHD);
Lex->sphead->new_cont_backpatch(NULL);
}
expr WHEN_SYM
{
LEX *lex= Lex;
sp_head *sp= lex->sphead;
sp_pcontext *parsing_ctx= lex->spcont;
int case_expr_id= parsing_ctx->register_case_expr();
sp_instr_set_case_expr *i;
if (parsing_ctx->push_case_expr_id(case_expr_id))
YYABORT;
i= new sp_instr_set_case_expr(sp->instructions(),
parsing_ctx,
case_expr_id,
$3,
lex);
sp->add_cont_backpatch(i);
sp->add_instr(i);
sp->m_flags|= sp_head::IN_SIMPLE_CASE;
sp->restore_lex(YYTHD);
}
sp_case END CASE_SYM
{
Lex->spcont->pop_case_expr_id();
Lex->sphead->do_cont_backpatch();
}
| case_stmt_specification
| sp_labeled_control
{}
| { /* Unlabeled controls get a secret label. */
@ -2242,72 +2347,114 @@ sp_elseifs:
| ELSE sp_proc_stmts1
;
sp_case:
{ Lex->sphead->reset_lex(YYTHD); }
expr THEN_SYM
{
case_stmt_specification:
simple_case_stmt
| searched_case_stmt
;
simple_case_stmt:
CASE_SYM
{
LEX *lex= Lex;
sp_head *sp= lex->sphead;
sp_pcontext *ctx= Lex->spcont;
uint ip= sp->instructions();
sp_instr_jump_if_not *i;
case_stmt_action_case(lex);
lex->sphead->reset_lex(YYTHD); /* For expr $3 */
}
expr
{
LEX *lex= Lex;
if (case_stmt_action_expr(lex, $3))
YYABORT;
if (! (sp->m_flags & sp_head::IN_SIMPLE_CASE))
i= new sp_instr_jump_if_not(ip, ctx, $2, lex);
else
{ /* Simple case: <caseval> = <whenval> */
lex->sphead->restore_lex(YYTHD); /* For expr $3 */
}
simple_when_clause_list
else_clause_opt
END
CASE_SYM
{
LEX *lex= Lex;
case_stmt_action_end_case(lex, true);
}
;
Item_case_expr *var;
Item *expr;
searched_case_stmt:
CASE_SYM
{
LEX *lex= Lex;
case_stmt_action_case(lex);
}
searched_when_clause_list
else_clause_opt
END
CASE_SYM
{
LEX *lex= Lex;
case_stmt_action_end_case(lex, false);
}
;
var= new Item_case_expr(ctx->get_current_case_expr_id());
simple_when_clause_list:
simple_when_clause
| simple_when_clause_list simple_when_clause
;
#ifndef DBUG_OFF
if (var)
var->m_sp= sp;
#endif
searched_when_clause_list:
searched_when_clause
| searched_when_clause_list searched_when_clause
;
expr= new Item_func_eq(var, $2);
simple_when_clause:
WHEN_SYM
{
Lex->sphead->reset_lex(YYTHD); /* For expr $3 */
}
expr
{
/* Simple case: <caseval> = <whenval> */
i= new sp_instr_jump_if_not(ip, ctx, expr, lex);
}
sp->push_backpatch(i, ctx->push_label((char *)"", 0));
sp->add_cont_backpatch(i);
LEX *lex= Lex;
case_stmt_action_when(lex, $3, true);
lex->sphead->restore_lex(YYTHD); /* For expr $3 */
}
THEN_SYM
sp_proc_stmts1
{
LEX *lex= Lex;
case_stmt_action_then(lex);
}
;
searched_when_clause:
WHEN_SYM
{
Lex->sphead->reset_lex(YYTHD); /* For expr $3 */
}
expr
{
LEX *lex= Lex;
case_stmt_action_when(lex, $3, false);
lex->sphead->restore_lex(YYTHD); /* For expr $3 */
}
THEN_SYM
sp_proc_stmts1
{
LEX *lex= Lex;
case_stmt_action_then(lex);
}
;
else_clause_opt:
/* empty */
{
LEX *lex= Lex;
sp_head *sp= lex->sphead;
uint ip= sp->instructions();
sp_instr_error *i= new sp_instr_error(ip, lex->spcont,
ER_SP_CASE_NOT_FOUND);
sp->add_instr(i);
sp->restore_lex(YYTHD);
}
sp_proc_stmts1
{
sp_head *sp= Lex->sphead;
sp_pcontext *ctx= Lex->spcont;
uint ip= sp->instructions();
sp_instr_jump *i = new sp_instr_jump(ip, ctx);
sp->add_instr(i);
sp->backpatch(ctx->pop_label());
sp->push_backpatch(i, ctx->push_label((char *)"", 0));
}
sp_whens
{
LEX *lex= Lex;
lex->sphead->backpatch(lex->spcont->pop_label());
}
;
sp_whens:
/* Empty */
{
sp_head *sp= Lex->sphead;
uint ip= sp->instructions();
sp_instr_error *i= new sp_instr_error(ip, Lex->spcont,
ER_SP_CASE_NOT_FOUND);
sp->add_instr(i);
}
| ELSE sp_proc_stmts1 {}
| WHEN_SYM sp_case {}
;
}
| ELSE sp_proc_stmts1
;
sp_labeled_control:
label_ident ':'
@ -4374,8 +4521,8 @@ simple_expr:
if (!$$)
YYABORT;
}
| CASE_SYM opt_expr WHEN_SYM when_list opt_else END
{ $$= new Item_func_case(* $4, $2, $5 ); }
| CASE_SYM opt_expr when_list opt_else END
{ $$= new Item_func_case(* $3, $2, $4 ); }
| CONVERT_SYM '(' expr ',' cast_type ')'
{
$$= create_func_cast($3, $5,
@ -5162,23 +5309,19 @@ opt_else:
| ELSE expr { $$= $2; };
when_list:
{ Select->when_list.push_front(new List<Item>); }
when_list2
{ $$= Select->when_list.pop(); };
when_list2:
expr THEN_SYM expr
{
SELECT_LEX *sel=Select;
sel->when_list.head()->push_back($1);
sel->when_list.head()->push_back($3);
}
| when_list2 WHEN_SYM expr THEN_SYM expr
{
SELECT_LEX *sel=Select;
sel->when_list.head()->push_back($3);
sel->when_list.head()->push_back($5);
};
WHEN_SYM expr THEN_SYM expr
{
$$= new List<Item>;
$$->push_back($2);
$$->push_back($4);
}
| when_list WHEN_SYM expr THEN_SYM expr
{
$1->push_back($3);
$1->push_back($5);
$$= $1;
}
;
/* Warning - may return NULL in case of incomplete SELECT */
table_ref: