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Remove redundant checked contexts around casts + more bounds checks #124184

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Merged
EgorBo merged 5 commits into from
Feb 11, 2026
Merged

Remove redundant checked contexts around casts + more bounds checks #124184

EgorBo merged 5 commits into from
Feb 11, 2026
+502 −60

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@EgorBo EgorBo commented Feb 9, 2026 •
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Example of a removed checked context:

public static byte Test(uint a)
{
    if (a > 100)
        return 0;
    return checked((byte)a); // checked is redundant here
}

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Copilot AI review requested due to automatic review settings February 9, 2026 16:54
@github-actions github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Feb 9, 2026
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dotnet-policy-service bot commented Feb 9, 2026

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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Pull request overview

This PR extends JIT assertion-based reasoning to (1) remove redundant overflow checks/casts when proven safe by range info and (2) enable additional bounds-check eliminations from inferred constant ranges.

Changes:

  • Promote RangeCheck::GetRangeFromType to be callable from assertion propagation, enabling range comparisons for cast redundancy decisions.
  • Enhance MergeEdgeAssertions to infer arr.Length > 0 from certain non-constant index assertions.
  • Add range-based bounds check elimination and adjust assertion-based non-negative/non-zero inference.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File Description
src/coreclr/jit/rangecheck.h Exposes GetRangeFromType for external (assertionprop) range reasoning.
src/coreclr/jit/rangecheck.cpp Improves edge-assertion merge logic, including deducing Length > 0 in more cases.
src/coreclr/jit/assertionprop.cpp Uses range reasoning to remove redundant casts/overflow checks and drop more bounds checks.

This was referenced Feb 9, 2026
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EgorBo commented Feb 9, 2026

/azp run Fuzzlyn

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azure-pipelines bot commented Feb 9, 2026

Azure Pipelines successfully started running 1 pipeline(s).

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@EgorBo EgorBo marked this pull request as ready for review February 10, 2026 00:24
Copilot AI review requested due to automatic review settings February 10, 2026 00:24
Copilot AI reviewed Feb 10, 2026
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Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

@build-analysis build-analysis bot mentioned this pull request Feb 11, 2026
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EgorBo commented Feb 11, 2026
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EgorBo commented Feb 11, 2026
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EgorBo commented Feb 11, 2026

PTAL @jakobbotsch @dotnet/jit-contrib

@EgorBo EgorBo requested a review from jakobbotsch February 11, 2026 12:05
@EgorBo EgorBo enabled auto-merge (squash) February 11, 2026 14:11
@EgorBo EgorBo merged commit 23c8cd9 into dotnet:main Feb 11, 2026
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@dotnet-maestro dotnet-maestro bot mentioned this pull request Feb 12, 2026
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@jakobbotsch jakobbotsch jakobbotsch approved these changes

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