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Propagate NeverNegative flag during CSE #125272

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EgorBo wants to merge 4 commits into from
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Propagate NeverNegative flag during CSE #125272

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8675e3a
Propagate NeverNegative flag during CSE
EgorBo Mar 6, 2026
f14be9d
Update src/coreclr/jit/compiler.h
EgorBo Mar 6, 2026
17dad03
Update optcse.cpp
EgorBo Mar 6, 2026
986e75c
Update optcse.cpp
EgorBo Mar 10, 2026
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4 changes: 4 additions & 0 deletions src/coreclr/jit/assertionprop.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6294,6 +6294,10 @@ PhaseStatus Compiler::optAssertionPropMain()
madeChanges |= optCreateJumpTableImpliedAssertions(switchBlock);
}

assert(!optLocalAssertionProp);
Metrics.GlobalAssertionCount = optAssertionCount;
Metrics.GlobalAssertionOverflow = optAssertionOverflow;

if (optAssertionCount == 0)
{
// Zero out the bbAssertionIn values, as these can be referenced in RangeCheck::MergeAssertion
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2 changes: 2 additions & 0 deletions src/coreclr/jit/jitmetadatalist.h
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Expand Up @@ -91,6 +91,8 @@ JITMETADATAMETRIC(NewArrayHelperCalls, int, 0)
JITMETADATAMETRIC(StackAllocatedArrays, int, 0)
JITMETADATAMETRIC(LocalAssertionCount, int, 0)
JITMETADATAMETRIC(LocalAssertionOverflow, int, 0)
JITMETADATAMETRIC(GlobalAssertionCount, int, 0)
JITMETADATAMETRIC(GlobalAssertionOverflow, int, 0)
JITMETADATAMETRIC(MorphTrackedLocals, int, 0)
JITMETADATAMETRIC(MorphLocals, int, 0)
JITMETADATAMETRIC(EnumeratorGDVProvisionalNoEscape, int, 0)
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8 changes: 8 additions & 0 deletions src/coreclr/jit/optcse.cpp
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Expand Up @@ -4866,6 +4866,14 @@ void CSE_HeuristicCommon::PerformCSE(CSE_Candidate* successfulCandidate)
lclDsc->lvType = cseLclVarTyp;
lclDsc->lvIsCSE = true;

// Propagate IsNeverNegative from the CSE expression to the temp.
// Mainly targeting Span.Length.
if (cseLclVarTyp == TYP_INT && successfulCandidate->Expr()->OperIs(GT_IND, GT_LCL_VAR) &&
successfulCandidate->Expr()->IsNeverNegative(m_compiler))
{
lclDsc->SetIsNeverNegative(true);
}

// Record that we created a new LclVar for use as a CSE temp
//
m_addCSEcount++;
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