TiDB sometimes produce inconsistent result for bit operations

[breezewish]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

This is an issue discovered by randgen:

https://internal.pingcap.net/idc-jenkins/blue/organizations/jenkins/tidb_ghpr_integration_copr_test/detail/tidb_ghpr_integration_copr_test/4098/pipeline/

Several bit operation related SQLs are failed, producing incorrect & inconsistent results. For example:

[2020-04-23T10:35:35.043Z] Statement: #22 -  SELECT `col_float_key` << ( ( '2016-09-24 08:37:18.025179' ^ `col_float_unsigned_key` ) >> 8642970634877403136 ) AS field1 FROM `table1_int_autoinc` WHERE ! `col_smallint_unsigned` LIMIT 8 /* QNO 24 CON_ID 96 */ ;
[2020-04-23T10:35:35.043Z] NoPushDown Output: 
[2020-04-23T10:35:35.043Z] field1
[2020-04-23T10:35:35.043Z] NULL
[2020-04-23T10:35:35.043Z] 
[2020-04-23T10:35:35.043Z] 
[2020-04-23T10:35:35.043Z] WithPushDown Output: 
[2020-04-23T10:35:35.043Z] field1
[2020-04-23T10:35:35.043Z] 

Test logs are available in

Test case sources are available in https://github.com/tikv/copr-test/tree/master/push-down-test/prepare

2. What did you expect to see?

All test pass

3. What did you see instead?

Test fails sometimes.

4. What version of TiDB are you using? (tidb-server -V or run select tidb_version(); on TiDB)

master

[qw4990]

Close since it cannot be reproduced. We can open it in the future if this problem occurs again.