[X86] Prefer reduced width multiplication over pmulld on Silvermont
Summary:
Prefer expansions such as: pmullw,pmulhw,unpacklwd,unpackhwd over pmulld.
On Silvermont [source: Optimization Reference Manual]:
PMULLD has a throughput of 1/11 [instruction/cycles].
PMULHUW/PMULHW/PMULLW have a throughput of 1/2 [instruction/cycles].
Fixes pr31202.
Analysis of this issue was done by Fahana Aleen.
Reviewers: wmi, delena, mkuper
Subscribers: RKSimon, llvm-commits
Differential Revision: https://reviews.llvm.org/D27203
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288844 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed