Alex Behm has uploaded a new change for review.

  http://gerrit.cloudera.org:8080/3033

Change subject: IMPALA-2809: Improved scalar ByteSwap().
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IMPALA-2809: Improved scalar ByteSwap().

This patch improves our ByteSwap() function by handling
more byte sizes in the fast path, as opposed to the
loop-based slow path.

ByteSwap() is used heavily in when scanning Parquet decimals.

Before this patch, VTune showed ByteSwap() among the top
three worst cycle offenders when running TPCH-Q6 on my local
setup with a large lineitem table.

After this patch, ByteSwap() shows no significant contribution
to the overall cycles spent.

There was a measurable improvement of a few percent for TPCH-Q6.

Change-Id: I4f462e6bdb022db46b48889a6a7426120a80d9b4
---
M be/src/util/bit-util.h
1 file changed, 92 insertions(+), 14 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala refs/changes/33/3033/1
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I4f462e6bdb022db46b48889a6a7426120a80d9b4
Gerrit-PatchSet: 1
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Alex Behm <[email protected]>

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