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[ARM] Simplify VMOVRRD from extracts of buildvectors

Authored by dmgreen on Jan 19 2021, 11:42 AM.



Under the softfp calling convention, we are often left with VMOVRRD(extract(bitcast(build_vector(a, b, c, d)))) for the return value of the function. These can be simplified to a,b or c,d directly, depending on the value of the extract.

Big endian is a little different because the bitcast switches the lanes around, meaning we end up with b,a or d,c.

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dmgreen created this revision.Jan 19 2021, 11:42 AM
dmgreen requested review of this revision.Jan 19 2021, 11:42 AM
Herald added a project: Restricted Project. · View Herald TranscriptJan 19 2021, 11:42 AM
SjoerdMeijer added inline comments.Jan 28 2021, 5:23 AM

Do we need a BE run here too?

dmgreen updated this revision to Diff 320421.Feb 1 2021, 2:46 AM

Rebase over D94990, showing the BE tests added there.

SjoerdMeijer accepted this revision.Feb 1 2021, 2:57 AM
This revision is now accepted and ready to land.Feb 1 2021, 2:57 AM
This revision was automatically updated to reflect the committed changes.