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 <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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