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From "Michael Ho (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4432: Handle internal codegen disabling properly
Date Mon, 21 Nov 2016 21:02:50 GMT
Michael Ho has posted comments on this change.

Change subject: IMPALA-4432: Handle internal codegen disabling properly
......................................................................


Patch Set 5:

(3 comments)

http://gerrit.cloudera.org:8080/#/c/5105/5/be/src/exec/exec-node.cc
File be/src/exec/exec-node.cc:

PS5, Line 463: CodegenDisabledByHint(
> is this correct? we might still codegen if there's an IR udf, right? See al
Good point. Fixed in the new patch.


http://gerrit.cloudera.org:8080/#/c/5105/5/be/src/runtime/runtime-state.h
File be/src/runtime/runtime-state.h:

PS5, Line 171: codegen is disabled due to hints
> is this true?  doesn't this just indicate whether the hint would like to di
Rephrased to "if there is hint to disable codegen."


PS5, Line 175: CodegenDisabledByHint
> if my above question is right, then this should be called CodegenDisableHin
The new patch introduces both CodegenDisableHint() and CodegenDisabledByHint().

The former is needed in ScalarFnCall::Prepare(). Ideally, if there is hint to disable codegen,
we should only codegen expressions which cannot be interpreted.  If we use CodegenDisabledByHint()
(with the suggested change) in ScalarFnCall::Prepare() and once an expression is added to
scalar_fn_calls_to_codegen_, all subsequent ScalarFnCall expressions will be codegen'd. This
makes it a bit non-deterministic which expressions will be codegen'd in the presence of the
disabling hints as it depends on the order of when Prepare() is called for the non-interpretable
expression.

That said, the expressions may still be codegen'd when the operator is codegen'd but this
logic may affect fe-support.cc and the above may matter in that case.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I0b6a9ed723c64ba21b861608583cc9b6607d3397
Gerrit-PatchSet: 5
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
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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