[llvm-dev] Vectorization in multiple threads

hameeza ahmed via llvm-dev llvm-dev at lists.llvm.org
Sun Jun 24 14:19:32 PDT 2018

I want to create multiple threads and do vectorization in each. like if my
loop has 2048 iterations it should be divided first into threads like if 4
threads so each thread should do 512 iterations using vector instructions
of length 64.

how to achieve this? i have tried using #pragma omp parallel for simd and
compiled using following;

clang  -S -emit-llvm 1.c -march=knl -O3 -fopenmp -mllvm
-disable-llvm-optzns -o 1.ll
opt  -S -O3 -force-vector-width=64  1.ll -o 1_o3.ll

i m getting this error;

remark: <unknown>:0:0: loop not vectorized: could not determine number of
loop iterations
warning: <unknown>:0:0: loop not vectorized: failed explicitly specified
loop vectorization

How to resolve this?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180625/de6219c2/attachment.html>

More information about the llvm-dev mailing list