dotnet/runtime

[JIT] Possible optimization for `x % {pow2_cns}` transformation for `ulong` types

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#81,189 opened on Jan 25, 2023

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 (1 comment) (0 reactions) (0 assignees)C# (5,445 forks)batch import
area-CodeGen-coreclrhelp wantedtenet-performance

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Description

At the moment, we do not optimize x % {pow2_cns} to x & (pow2_cns - 1) for ulong types as they get transformed differently in morph.cpp. I believe we should only do this for X64 and not X86.

Contributor guide

Research direction
Investigate morph.cpp in the dotnet/runtime repository to understand the existing optimization for `x % pow2 cns` for signed and unsigned integer types. The issue notes that ulong types are not transformed to `x & (pow2 cns 1)` because they are handled differently. Review the comment in the issue for additional context. Ensure the optimization is applied only for X64, not X86, and verify via testing.
Tech stack
csharpcpp
Domain
backendperformance
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++ programmingJIT compiler internalsx64 architecture basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35