JIT: avoid fp divide by zero in profile synthesis #113396
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This can trip up users that have enabled floating point exceptions. While we don't generally support changing the exception modes we also can easily avoid dividing by zero here. Addresses dotnet#113369
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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@amanasifkhalid PTAL Should be no diff. |
amanasifkhalid
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Mar 11, 2025
hez2010
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Mar 12, 2025
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| weight_t const smallFractionOfChange = 1e-9 * change; | ||
| weight_t relDivisor = oldWeight; | ||
| if (relDivisor < smallFractionOfChange) | ||
| { | ||
| relDivisor = smallFractionOfChange; | ||
| } | ||
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| weight_t const blockRelResidual = change / relDivisor; |
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Wondering can't it just be something like weight_t const blockRelResidual = change / (oldWeight + 1e-10)?
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Yeah, that would have worked too.
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Turns out @hez2010 had a better fix. If change is zero we will end up with 0.0 / 0.0 which causes an "invalid FP operation" exception.
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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/13814988612 |
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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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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.
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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.
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This can trip up users that have enabled floating point exceptions.
While we don't generally support changing the exception modes we also can easily avoid dividing by zero here.
Addresses #113369