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JIT: Skip cost improvement check in 3-opt for exceptionally costly layouts #110069

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amanasifkhalid merged 3 commits into from
Nov 22, 2024
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JIT: Skip cost improvement check in 3-opt for exceptionally costly layouts #110069

amanasifkhalid merged 3 commits into from
Nov 22, 2024

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@amanasifkhalid amanasifkhalid commented Nov 21, 2024

Fixes #109984.

@ghost ghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Nov 21, 2024
teo-tsirpanis
teo-tsirpanis reviewed Nov 22, 2024
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src/coreclr/jit/fgopt.cpp Outdated
//
// Returns:
// The region's layout cost
// The region's layout cost, or 'BB_MAX_WEIGHT' for pathalogically costly layouts
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Suggested change
// The region's layout cost, or 'BB_MAX_WEIGHT' for pathalogically costly layouts
// The region's layout cost, or 'BB_MAX_WEIGHT' for pathologically costly layouts

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amanasifkhalid commented Nov 22, 2024

/azp run runtime-coreclr libraries-jitstress, Antigen

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dont wanna approve anything

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amanasifkhalid commented Nov 22, 2024

/azp run runtime-coreclr libraries-jitstress

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Azure Pipelines successfully started running 1 pipeline(s).

@amanasifkhalid amanasifkhalid changed the title JIT: Detect and handle imprecision in 3-opt layout cost computation JIT: Skip cost improvement check in 3-opt for exceptionally costly layouts Nov 22, 2024
@amanasifkhalid amanasifkhalid marked this pull request as ready for review November 22, 2024 18:32
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amanasifkhalid commented Nov 22, 2024

cc @dotnet/jit-contrib, @AndyAyersMS PTAL. libraries-jitstress failures don't look related. For the cases I looked at, the failure in #109984 only seems to hit under JitOptRepeat stress scenarios where optSetBlockWeights inflates loop block weights, thus causing the layout cost calculation to lose precision when summing large values. The simplest solution seems to be to skip the assertion if we detect that we're dealing with some pathologically large layout cost.

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amanasifkhalid commented Nov 22, 2024

/ba-g Linux-arm64 NativeAOT build timed out.

@amanasifkhalid amanasifkhalid merged commit 4045d1b into dotnet:main Nov 22, 2024
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@amanasifkhalid amanasifkhalid deleted the fix-3-opt-assert-pt2 branch November 22, 2024 19:57
mikelle-rogers pushed a commit to mikelle-rogers/runtime that referenced this pull request Dec 10, 2024
@amanasifkhalid @mikelle-rogers
JIT: Skip cost improvement check in 3-opt for exceptionally costly la…
2027f69 
…youts (dotnet#110069)

Fixes dotnet#109984.
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@AndyAyersMS AndyAyersMS AndyAyersMS approved these changes

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