dotnet/runtime

Add code to verify that operations on short/long bitsets operate on the correct epoch.

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#7,957 opened on Apr 26, 2017

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area-CodeGen-coreclrhelp wanted

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Description

See the discussion in https://github.com/dotnet/coreclr/pull/11233 for more details.

These bitsets currently have no checks to ensure that the epoch in which a bitset was created matches the epoch in which it is being used. Depending on the actual representation and the operation, mismatching epochs can have a variety of harmful effects as they can cause out-of-bounds reads or writes.

@BruceForstall writes

Ideally, we would implement a DEBUG ShortLong representation bitset that also carried epoch along with every bitset, and asserted that operations between two bitsets were in the same epoch.

Which seems like a good suggestion.

category:testing theme:jit-coding-style skill-level:intermediate cost:small impact:small

Contributor guide

Research direction
Examine the ShortLong bitset implementation and add DEBUG only epoch checks to ensure operations are performed on bitsets with matching epochs.
Tech stack
csharp
Domain
compilers
Issue type
Test
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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
C#debugging
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65