Skye Wanderman-Milne has posted comments on this change.

Change subject: IMPALA-2548: Codegen Tuple::MaterializeExprs() and use in TopN 
node
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Patch Set 6:

(3 comments)

http://gerrit.cloudera.org:8080/#/c/1901/6/be/src/exec/topn-node.cc
File be/src/exec/topn-node.cc:

Line 84:   insert_batch_fn = codegen->ReplaceCallSites(insert_batch_fn, false,
> I think a more reliable way would be to also compare the arg list and ret t
I gave them the same signature so CodegenMaterializeExprs() always returns a 
function with the same signature (I thought it would be confusing otherwise), 
but I could change this. LLVM will complain if we try to call a function with 
the wrong arguments too.


http://gerrit.cloudera.org:8080/#/c/1901/6/be/src/runtime/tuple.cc
File be/src/runtime/tuple.cc:

Line 327: GetPtrType(ExprContext::LLVM_CLASS_NAME)->getPointerTo();
> Sounds good to me if that doesn't make it too verbose to write certain expr
'->getPointerTo' is fewer characters than 'codegen->GetPtrType' as well, so 
it's actually less verbose usually.


http://gerrit.cloudera.org:8080/#/c/1901/6/be/src/runtime/tuple.h
File be/src/runtime/tuple.h:

Line 122: std::vector<StringValue*>* non_null_string_values =
> How about using vector::data() ?
I'm fine with using vector.data(). I compiled a quick test program and it 
appears to generate the same instructions as &vector[0],

The argument against it would be that it's inconsistent with the rest of the 
code base, but it also looks like the new (as of C++11) canonical access 
method, plus &vector[0] on an empty vector is technically undefined behavior 
(even though in practice it's the same as .data() apparently). I'll change it 
here and see if anyone else has an opinion.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ib422a8d50303c21c6a228675157bf867e8619444
Gerrit-PatchSet: 6
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Skye Wanderman-Milne <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Skye Wanderman-Milne <[email protected]>
Gerrit-HasComments: Yes

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