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Create ">=0" assertion for unpromoted Span.Length #130326

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Create ">=0" assertion for unpromoted Span.Length #130326

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12 changes: 12 additions & 0 deletions src/coreclr/jit/assertionprop.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2192,6 +2192,18 @@ void Compiler::optAssertionGen(GenTree* tree)
{
assertionInfo = optCreateAssertion(tree->GetIndirOrArrMetaDataAddr(), nullptr, /*equals*/ false);
}
else if (tree->OperIs(GT_IND) && tree->TypeIs(TYP_INT) &&
IntegralRange::ForNode(tree, this).IsNonNegative())
{
// Create "IND >= 0" assertion for int indirections that are known to be non-negative.
// Mainly, this is for unpromoted Span.Length indirections.
ValueNum vn = optConservativeNormalVN(tree);
if (vn != ValueNumStore::NoVN)
{
assertionInfo = optAddAssertion(
AssertionDsc::CreateConstantBound(this, VNF_GE, vn, vnStore->VNZeroForType(TYP_INT)));
}
}
break;

case GT_INTRINSIC:
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18 changes: 6 additions & 12 deletions src/coreclr/jit/rangecheck.cpp
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Expand Up @@ -2294,6 +2294,11 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
range = Limit(Limit::keUnknown);
}
}
// If this value IS the caller-provided preferred bound, represent it as [bound, bound]
else if ((m_preferredBound != ValueNumStore::NoVN) && (vn == m_preferredBound))
{
range = Range(Limit(Limit::keBinOpArray, m_preferredBound, 0));
}
// If local, find the definition from the def map and evaluate the range for rhs.
else if (expr->IsLocal())
{
Expand Down Expand Up @@ -2340,18 +2345,7 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
}
else if (expr->OperIs(GT_ARR_LENGTH))
{
ValueNum arrLenVN = m_compiler->optConservativeNormalVN(expr);
if ((arrLenVN != ValueNumStore::NoVN) && (arrLenVN == m_preferredBound))
{
// If the ARR_LENGTH VN matches the bounds check's length VN, represent it symbolically
// so the PHI merge can combine it with other symbolic ranges referencing the same bound.
range = Range(Limit(Limit::keConstant, 0), Limit(Limit::keBinOpArray, arrLenVN, 0));
}
else
{
// Better than keUnknown
range = Range(Limit(Limit::keConstant, 0), Limit(Limit::keConstant, CORINFO_Array_MaxLength));
}
range = Range(Limit(Limit::keConstant, 0), Limit(Limit::keConstant, CORINFO_Array_MaxLength));
}
else
{
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