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[AArch64] Model Cortex-A55 Q register NEON instructions
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Authored by dmgreen on Aug 26 2021, 7:32 AM.

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Summary

Cortex-A55 has 2 64bit NEON vector units, meaning a 128bit instruction requires taking both units (and can only be issued as the first instruction in a dual issue pair). This patch models that by splitting the WriteV SchedWrite into two - the WriteVd that reads/writes only 64bit operands, and the WriteVq that read/writes 128bit registers. The A55 schedule then uses this distinction to model the WriteVq as taking both resource units, and starting a Schedule Group and WriteVd as taking one as before.

I believe this is more correct, even if it does not lead to much better performance.

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Event Timeline

dmgreen created this revision.Aug 26 2021, 7:32 AM
dmgreen requested review of this revision.Aug 26 2021, 7:32 AM
Herald added a project: Restricted Project. · View Herald TranscriptAug 26 2021, 7:32 AM
NickGuy accepted this revision.Sep 28 2021, 2:23 AM

LGTM

This revision is now accepted and ready to land.Sep 28 2021, 2:23 AM
Matt added a subscriber: Matt.Sep 28 2021, 12:11 PM
This revision was automatically updated to reflect the committed changes.