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[SampleFDO] handle ProfileSampleAccurate when initializing function entry count
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Authored by wmi on Dec 13 2018, 9:35 AM.

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Summary

ProfileSampleAccurate is used to indicate the profile has exact match to the code to be optimized.

Previously ProfileSampleAccurate is handled in ProfileSummaryInfo::isColdCallSite and ProfileSummaryInfo::isColdBlock. A better solution is to initialize function entry count to 0 when ProfileSampleAccurate is true, so we don't have to handle ProfileSampleAccurate in multiple places.

Thanks to Easwaran for the idea to the improvement.

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rL LLVM

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wmi created this revision.Dec 13 2018, 9:35 AM
tejohnson accepted this revision.Dec 13 2018, 9:44 AM

Nice! lgtm

test/Transforms/SampleProfile/section-accurate-samplepgo.ll
6 ↗(On Diff #178084)

Nit: line length

This revision is now accepted and ready to land.Dec 13 2018, 9:44 AM

Could you add a test case or augment an existing test to check that the function entry count is 0 if -sample-profile and -profile-sample-accurate is specified?

lib/Transforms/IPO/SampleProfile.cpp
129 ↗(On Diff #178084)

To be more precise, you are now marking all un-sampled functions as having entry count 0 (not just cold)

test/Transforms/SampleProfile/inline-cold-callsite-samplepgo.ll
7 ↗(On Diff #178084)

Nit: You probably just need a single call void @extern() in the body to make this not inlineable when threshold is 0.

wmi marked 3 inline comments as done.Dec 13 2018, 11:14 AM

Could you add a test case or augment an existing test to check that the function entry count is 0 if -sample-profile and -profile-sample-accurate is specified?

I augmented test/Transforms/SampleProfile/section-accurate-samplepgo.ll to check that.

wmi updated this revision to Diff 178098.Dec 13 2018, 11:16 AM

Address Easwaran and Teresa's comments.

wmi updated this revision to Diff 178100.Dec 13 2018, 11:27 AM

Fix test/Transforms/SampleProfile/inline-cold-callsite-samplepgo.ll which was over simplified in the last revision.

eraman accepted this revision.Dec 13 2018, 1:12 PM

LGTM

This revision was automatically updated to reflect the committed changes.