BUG#860580: Sporadic crash / valgrind warning in register_field_in_read_map() with semijoin The problem: in an uncorrelated subquery, JOIN execution code may make  irreversible cleanups after it has been executed (because the subquery  won't be executed again). In particular, JTBM nests and their injected  IN-equalities will be invalidated (the materialized table will be dropped and TABLE structure freed). Solution: don't walk into Item_subselect if represents an uncorrelated  subselect that has already been executed. The idea is that the subselect will not be executed again (calling Item_subselect_xxx::val_int() will fetch the cached value), so it should not matter what is inside the subselect.
BUG#860580: Sporadic crash / valgrind warning in register_field_in_read_map() with semijoin
The problem: in an uncorrelated subquery, JOIN execution code may make 
irreversible cleanups after it has been executed (because the subquery 
won't be executed again). In particular, JTBM nests and their injected 
IN-equalities will be invalidated (the materialized table will be dropped
and TABLE structure freed).
Solution: don't walk into Item_subselect if represents an uncorrelated 
subselect that has already been executed. The idea is that the subselect
will not be executed again (calling Item_subselect_xxx::val_int() will fetch
the cached value), so it should not matter what is inside the subselect.

ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server,slanterns/server,natsys/mariadb_10.2,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix,flynn1973/mariadb-aix,davidl-zend/zenddbi,ollie314/server,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server