golang/go

cmd/compile: OpInlMark can get removed by SSA dead code elimination, resulting in invalid inlining trees

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#54,625 opened on Aug 23, 2022

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Description

See discussion at https://github.com/golang/go/issues/46234.

The immediate issue is that https://go.dev/play/p/OikFLBmKguY?v=gotip causes the loop at https://github.com/golang/go/blob/7f632f76db65f28038b8797fbfe5e15a9f63e387/src/runtime/traceback.go#L362 to never terminate, because the inlining "tree" has cycles.

The bigger issue is that we're generating trees like this for kube-apiserver, and this is presumably the root cause of #54593.

Contributor guide

Research direction
Trace the SSA dead code elimination pass to understand how OpInlMark is removed, and examine the inlining tree generation in the compiler to identify the cycle cause.
Tech stack
go
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Gocompiler internalsSSA
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20