[llvm-dev] Llvm-mca library.

Shoaib Meenai via llvm-dev
Thu, 02 May 2019 18:34:06 -0000

(Adding Matt Davis, who should be able to help out here.)

From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of lorenzo
chelini via llvm-dev <llvm-dev at lists.llvm.org>
Reply-To: lorenzo chelini <l.chelini at icloud.com>
Date: Thursday, May 2, 2019 at 4:15 AM
To: "llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>
Subject: [llvm-dev] Llvm-mca library.

Hi All,

I would like to use llvm-mca to estimate the IPC of a given code region. I am
interested in the library version
(https://reviews.llvm.org/D50929?id=162210<https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D50929-3Fid-3D162210&d=DwMFAg&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Ehy5cbFrTOTrtNpj4jTjwnMXspCxyoUuKpn3m8pxGpg&s=iEwPb0T8FqcGV-IscWqa3SAw64L-buGNLYvMLOgWoi4&e=>)
but I have troubles understanding how to use it. Could you please point me to
some documentations or (better) some code examples if any?

Reading the documentation
(https://llvm.org/docs/CommandGuide/llvm-mca.html<https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_docs_CommandGuide_llvm-2Dmca.html&d=DwMFAg&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Ehy5cbFrTOTrtNpj4jTjwnMXspCxyoUuKpn3m8pxGpg&s=5845DcPA4uSN_lgPE_SlH6XwRSShIfPIvYR1t8AZHpU&e=>)
it also seems that llvm-mca does not take into account the cache hierarchy. Does
this mean that the tool assumes all the loads/stores hit the L1 cache?

Looking forward to hearing from you.
Best regards,

Lorenzo Chelini.
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