[Lldb-commits] [PATCH] D136610: [trace][intelpt] Fix multi CPU decoding TSC assertion error

[Jakob Johnson via Phabricator via lldb-commits]

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Occasionally the assertion that enforces increasing TSC values in `DecodedThread::NotifyTsc`
would get tripped during large multi CPU trace decoding.
The root cause of this issue was an assumption that all the data of a
PSB will fit within the start,end TSC of the "owning"
`ThreadContinuousExecution`. After investigating, this is not the case
because PSBs can have multiple TSCs.
This diff works around this issue by introducing a TSC upper bound for
each `PSBBlockDecoder`. This fixes the assertion failure by simply
"dropping" the remaining data of PSB whenever the TSC upper bound is
exceeded during decoding.
Future work will do a larger refactor of the multi CPU decoding to
remove the dependencies on this incorrect assumption so that PSB blocks
that span multiple `ThreadContinuousExecutions` are correctly handled.
correctly

Test Plan:


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D136610

Files:
  lldb/source/Plugins/Trace/intel-pt/LibiptDecoder.cpp

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