dotnet/runtime

Consider adding a stress mode which prefers registers with different encoding characteristics

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#10,647 opened on Jul 9, 2018

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area-CodeGen-coreclrhelp wantedtest-enhancement

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Description

On various architectures there exist registers that require different encoding characteristics. For example, on x64 there are additional registers available (R8-R15 and XMM8-XMM15), which require the use of the REX prefix (or a VEX-encoded instruction).

Given that these change how the instruction is encoded, it would be beneficial if there was a stress-mode that would prefer these registers in order to help validate that the emitter has them properly handled.

category:testing theme:register-allocator skill-level:beginner cost:small

Contributor guide

Research direction
Study the register allocator in the RyuJIT compiler, identify the encoding differences for registers R8 R15 and XMM8 XMM15, and implement a stress mode that prefers these registers to validate emitter correctness.
Tech stack
csharp
Domain
compilerstesting
Issue type
Feature
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#Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80