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Michael Pratt authored
Today, the PGO IR graph only contains entries for ir.Func loaded into the package. This can include functions from transitive dependencies, but only if they happen to be referenced by something in the current package. If they are not referenced, noder never bothers to load them. This leads to a deficiency in PGO devirtualization: some callee methods are available in transitive dependencies but do not devirtualize because they happen to not get loaded from export data. Resolve this by adding an explicit lookup from export data of callees mentioned in the profile. I have chosen to do this during loading of the profile for simplicity: the PGO IR graph always contains all of the functions we might need. That said, it isn't strictly necessary. PGO devirtualization could do the lookup lazily if it decides it actually needs a method. This saves work at the expense of a bit more complexity, but I've chosen the simpler approach for now as I measured the cost of this as significantly less than the rest of PGO loading. For #61577. Change-Id: Ieafb2a549510587027270ee6b4c3aefd149a901f Reviewed-on: https://go-review.googlesource.com/c/go/+/497175 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by:
Matthew Dempsky <mdempsky@google.com> Reviewed-by:
Cherry Mui <cherryyz@google.com>
Michael Pratt authoredToday, the PGO IR graph only contains entries for ir.Func loaded into the package. This can include functions from transitive dependencies, but only if they happen to be referenced by something in the current package. If they are not referenced, noder never bothers to load them. This leads to a deficiency in PGO devirtualization: some callee methods are available in transitive dependencies but do not devirtualize because they happen to not get loaded from export data. Resolve this by adding an explicit lookup from export data of callees mentioned in the profile. I have chosen to do this during loading of the profile for simplicity: the PGO IR graph always contains all of the functions we might need. That said, it isn't strictly necessary. PGO devirtualization could do the lookup lazily if it decides it actually needs a method. This saves work at the expense of a bit more complexity, but I've chosen the simpler approach for now as I measured the cost of this as significantly less than the rest of PGO loading. For #61577. Change-Id: Ieafb2a549510587027270ee6b4c3aefd149a901f Reviewed-on: https://go-review.googlesource.com/c/go/+/497175 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by:
Matthew Dempsky <mdempsky@google.com> Reviewed-by:
Cherry Mui <cherryyz@google.com>
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