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Fix bug MDEV-4895 Valgrind warnings (Conditional jump or move depends on uninitialised value) in Field_datetime::get_date on GREATEST(..) IS NULL

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Analysis:
The cause of the valgrind warning was an attempt to evaluate a Field that was not yet read.
The reason was that on one hand Item_func_isnotnull was marked as constant by
Item_func_isnotnull::update_used_tables, and this allowed eval_const_cond() to be called.
On the other hand Item_func_isnotnull::val_int() evaluated its argument as if it was not
constant.

Solution:
The fix make sure that Item_func_isnotnull::val_int() doesn't evaluate its argument when
it is constant and cannot be NULL, because the result is known in this case.
This commit is contained in:
unknown
2013-08-20 17:08:03 +03:00
parent 008371b627
commit 5fdb531d77
3 changed files with 62 additions and 0 deletions
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30
mysql-test/r/null.result
View File

@ -343,3 +343,33 @@ Field Type Null Key Default Extra
IFNULL(NULL, b) decimal(1,0) YES NULL
DROP TABLE t1, t2;
# End of 5.0 tests
#
# MDEV-4895 Valgrind warnings (Conditional jump or move depends on uninitialised value) in Field_datetime::get_date on GREATEST(..) IS NULL
#
CREATE TABLE t1 (dt DATETIME NOT NULL);
INSERT INTO t1 VALUES (NOW()),(NOW());
EXPLAIN
SELECT * FROM t1 WHERE concat( dt, '2012-12-21 12:12:12' ) IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
SELECT * FROM t1 WHERE concat( dt, '2012-12-21 12:12:12' ) IS NULL;
dt
drop table t1;
CREATE TABLE t1 (dt INT NOT NULL);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN
SELECT * FROM t1 WHERE concat( dt, '1' ) IS NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
SELECT * FROM t1 WHERE concat( dt, '1' ) IS NULL;
dt
drop table t1;
CREATE TABLE t1 (dt INT NOT NULL);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN
SELECT * FROM t1 WHERE NOT (concat( dt, '1' ) IS NOT NULL);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
SELECT * FROM t1 WHERE NOT (concat( dt, '1' ) IS NOT NULL);
dt
drop table t1;

28
mysql-test/t/null.test
View File

@ -255,3 +255,31 @@ DESCRIBE t2;
DROP TABLE t1, t2;
--echo # End of 5.0 tests
--echo #
--echo # MDEV-4895 Valgrind warnings (Conditional jump or move depends on uninitialised value) in Field_datetime::get_date on GREATEST(..) IS NULL
--echo #
CREATE TABLE t1 (dt DATETIME NOT NULL);
INSERT INTO t1 VALUES (NOW()),(NOW());
EXPLAIN
SELECT * FROM t1 WHERE concat( dt, '2012-12-21 12:12:12' ) IS NULL;
SELECT * FROM t1 WHERE concat( dt, '2012-12-21 12:12:12' ) IS NULL;
DROP TABLE t1;
CREATE TABLE t1 (dt INT NOT NULL);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN
SELECT * FROM t1 WHERE concat( dt, '1' ) IS NULL;
SELECT * FROM t1 WHERE concat( dt, '1' ) IS NULL;
DROP TABLE t1;
CREATE TABLE t1 (dt INT NOT NULL);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN
SELECT * FROM t1 WHERE NOT (concat( dt, '1' ) IS NOT NULL);
SELECT * FROM t1 WHERE NOT (concat( dt, '1' ) IS NOT NULL);
DROP TABLE t1;