JIT: revised fix for fp division issue in profile synthesis #115005
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The previous fix dotnet#113396 could still leave us trying to evaluate 0.0/0.0, which causes an invalid FP operation exception. Make sure the divisor is non-zero.
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Pull Request Overview
This PR revises the fix for an FP division issue in profile synthesis to ensure that a division by an extremely small value (or zero) is avoided.
- Replaces previous conditional logic with a call to max(oldWeight, 1e-12).
- Simplifies the calculation of blockRelResidual using a lower bound threshold.
Comments suppressed due to low confidence (1)
src/coreclr/jit/fgprofilesynthesis.cpp:1394
- Ensure that the use of max() correctly handles cases where oldWeight might be negative, if such cases are possible, to prevent unintended behavior.
weight_t const blockRelResidual = change / max(oldWeight, 1e-12);
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@dotnet/jit-contrib PTAL No diffs. Verified a port of this to 9.0 fixes the issue. |
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
EgorBo
approved these changes
Apr 24, 2025
Yeah we don't want to divide by anything super-small, just small. |
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/backport to release/9.0-staging |
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Started backporting to release/9.0-staging: https://github.com/dotnet/runtime/actions/runs/14653363543 |
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The previous fix #113396 could still leave us trying to evaluate 0.0/0.0, which causes an invalid FP operation exception.
Make sure the divisor is non-zero.