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From "Dan Hecht (Code Review)" <ger...@cloudera.org>
Subject [Impala-CR](cdh5-trunk) IMPALA-3115: Hoist some variables out of loops in cross-compiled code.
Date Fri, 15 Apr 2016 23:48:58 GMT
Dan Hecht has posted comments on this change.

Change subject: IMPALA-3115: Hoist some variables out of loops in cross-compiled code.
......................................................................


Patch Set 5:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/2661/5/be/src/runtime/row-batch.h
File be/src/runtime/row-batch.h:

Line 172:       ++row_idx_;
> that might be fine, but then let's not put it in this class since we wouldn
Hmm, actually isn't this method effectively the same as Tuple::next_row()? Why not just use
that in those loops rather than introduce a new iterator?  Or it seems like next_row() should
go away (and be replaced by this iterator - but I don't see why we should have both).

Yet another way to think of the problem you are trying to solve with this iterator is that
num_tuples_per_row_ is not constant. We could inject it to codegen, and then the compiler
should be able to use a 'base + scale * index' addressing mode which is effectively free (once
scale is a constant).  But using next_row() should be okay too.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ic7152b1fb094b3c3574d203e3774f4297f2225dc
Gerrit-PatchSet: 5
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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