[LLVMdev] Enabling the SLP vectorizer by default for -O3
nrotem at apple.com
Sat Jul 13 23:30:33 PDT 2013
LLVM’s SLP-vectorizer is a new pass that combines similar independent instructions in a straight-line code. It is currently not enabled by default, and people who want to experiment with it can use the clang command line flag “-fslp-vectorize”. I ran LLVM’s test suite with and without the SLP vectorizer on a Sandybridge mac (using SSE4, w/o AVX). Based on my performance measurements (below) I would like to enable the SLP-vectorizer by default on -O3. I would like to hear what others in the community think about this and give other people the opportunity to perform their own performance measurements.
— Performance Gains —
— Regressions —
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