DBC: Fix smi shl with large (>word-size) shift counts

DBC: Fix smi shl with large (>word-size) shift counts

Insert check to guard against large shift counts.

Integer shifts with shift counts greater or equal than the number
of bits per word are undefined behavior in C/C++.

Fixes #27474.

R=vegorov@google.com

Committed: https://github.com/dart-lang/sdk/commit/6fa4a54bba4c69bbd5fc15bc3ec50e4e8812776b

[Florian Schneider, 2016-11-04 10:54:48]

fschneider@google.com changed reviewers:
+ vegorov@google.com

[Vyacheslav Egorov (Google), 2016-11-04 10:56:52]

lgtm

[Florian Schneider, 2016-11-04 11:15:56]

Thanks.

I had to update a co19 test which is now passing on simdbc as well.

[Florian Schneider, 2016-11-04 11:16:40]

Description was changed from

==========
DBC: Fix smi shl with large (>word-size) shift counts

Insert check to guard against large shift counts.

Integer shifts with shift counts greater or equal than the number
of bits per word are undefined behavior in C/C++.

Fixes #27474.
==========

to

==========
DBC: Fix smi shl with large (>word-size) shift counts

Insert check to guard against large shift counts.

Integer shifts with shift counts greater or equal than the number
of bits per word are undefined behavior in C/C++.

Fixes #27474.

R=vegorov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/6fa4a54bba4c69bbd5fc15bc3ec50e4e8812776b
==========

[Florian Schneider, 2016-11-04 11:16:41]

Committed patchset #3 (id:40001) manually as
6fa4a54bba4c69bbd5fc15bc3ec50e4e8812776b (presubmit successful).