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From "Jim Apple (Code Review)" <>
Subject [Impala-CR](cdh5-trunk) IMPALA-2809: Improve ByteSwap with builtin function or SSE or AVX2.
Date Sun, 22 May 2016 22:32:57 GMT
Jim Apple has posted comments on this change.

Change subject: IMPALA-2809: Improve ByteSwap with builtin function or SSE or AVX2.

Patch Set 5:

File be/src/util/bit-util.inline.h:

Line 139: __attribute__((target("sse4.2")))
> Hi Jim. This issue has been discussed with some other engineers from Cloude
You have explained it clearly; thank you!

I agree with what you said, but, given that we seem to compile with -march=x86-64, do these
functions actually get picked up by the compiler and compiled; that is, do their  __attribute__
targets become active during compilation?

Line 174:   static const FuncPointer SIMDFuncTable[2] = {ByteSwapSSE_Unit, ByteSwapAVX2_Unit};
> Hi Jim. Thank you so much for your clarification. As you can see here, the 
I don't know what "polynomial", you are referring to. I think you should check to see if a
run-time computation is being made to calculate func_idx, and, if so, remove it by lifting
the computation of func_idx to a compile-time constant.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I392ed5a8d5683f30f161282c228c1aedd7b648c1
Gerrit-PatchSet: 5
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Youwei Wang <>
Gerrit-Reviewer: Alex Behm <>
Gerrit-Reviewer: Jim Apple <>
Gerrit-Reviewer: Marcel Kornacker <>
Gerrit-Reviewer: Mostafa Mokhtar <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-Reviewer: Youwei Wang <>
Gerrit-HasComments: Yes

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