[PATCH] D41323: [X86][SSE] Add cpu feature for aggressive combining to variable shuffles
Zvi Rackover via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 20 14:51:38 PST 2017
zvi added a comment.
In https://reviews.llvm.org/D41323#960715, @RKSimon wrote:
> I've created https://reviews.llvm.org/D41436 - the main issue is whether KNL prefers variable shuffles the same as SkylakeServer
The Intel Optimization Reference Manual is the only source of information i have for KNL. It says that of the two core's VPUs, one can execute shuffles. It says that single-source shuffles have a reciprocal throughput of 1 cycle, dual-source shuffles have a reciprocal throughput of 2 cycles. So i don't have any information indicating that KNL differs from SKX in preference of variable-shuffles.
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