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Have ComputeRange call into GetRangeFromAssertions for non dependent/symbolic cases #128922

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Merged
tannergooding merged 1 commit into from
Jun 3, 2026
+19 −14
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Have ComputeRange call into GetRangeFromAssertions for non dependent/symbolic cases #128922

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33 changes: 19 additions & 14 deletions src/coreclr/jit/rangecheck.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1201,7 +1201,7 @@ void RangeCheck::MergeEdgeAssertionsWorker(Compiler* comp
ValueNumStore::SmallValueNumSet* visited)
{
Range assertedRange = Range(Limit(Limit::keUnknown));
if (BitVecOps::IsEmpty(comp->apTraits, assertions))
if (BitVecOps::MayBeUninit(assertions) || BitVecOps::IsEmpty(comp->apTraits, assertions))
{
return;
}
Expand Down Expand Up @@ -2287,9 +2287,19 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
// If VN is constant return range as constant.
else if (m_compiler->vnStore->IsVNConstant(vn))
{
range = (m_compiler->vnStore->TypeOfVN(vn) == TYP_INT)
? Range(Limit(Limit::keConstant, m_compiler->vnStore->ConstantValue<int>(vn)))
: Limit(Limit::keUnknown);
// We want to handle constants first since it can avoid other more expensive work

int cns;
if (m_compiler->vnStore->IsVNIntegralConstant(vn, &cns))
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{
range = Range(Limit(Limit::keConstant, cns));
}
else
{
// TODO: We could return `0, keUnknown` if the constant is known positive
// but this would require more handling in other places to take advantage of.
range = Limit(Limit::keUnknown);
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@EgorBo EgorBo Jun 3, 2026

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I don't think we can TBH, a never-negative long that doesn't fit into INT32 can be negative when casted to INT32?

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@tannergooding tannergooding Jun 3, 2026

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Wouldn’t that be handled by the cast?

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@EgorBo EgorBo Jun 3, 2026

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I meant I don't see what we can possibly do for a LONG that doesn't fit into INT here

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@tannergooding tannergooding Jun 3, 2026

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It's the same consideration as for TYP_INT.

Which is that the MSB is never set for this target format and so therefore shifts, mods, and various other operations can be optimized as the unsigned variants.

If we cast from TYP_LONG to TYP_INT and the value is unknown, then the cast result might be negative, in the same way that TYP_INT -> TYP_BYTE might produce a negative result, and so the same optimizations on the cast result are then not possible.

}
}
// If local, find the definition from the def map and evaluate the range for rhs.
else if (expr->IsLocal())
Expand Down Expand Up @@ -2331,20 +2341,10 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
JITDUMP("%s\n", range.ToString(m_compiler));
}
}
else if (varTypeIsSmall(expr))
{
range = GetRangeFromType(expr->TypeGet());
JITDUMP("%s\n", range.ToString(m_compiler));
}
else if (expr->OperIs(GT_COMMA))
{
range = GetRangeWorker(block, expr->gtEffectiveVal(), monIncreasing DEBUGARG(indent + 1));
}
else if (expr->OperIs(GT_CAST))
{
// TODO: consider computing range for CastOp and intersect it with this.
range = GetRangeFromType(expr->AsCast()->CastToType());
}
else if (expr->OperIs(GT_ARR_LENGTH))
{
ValueNum arrLenVN = m_compiler->optConservativeNormalVN(expr);
Expand All @@ -2360,6 +2360,11 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
range = Range(Limit(Limit::keConstant, 0), Limit(Limit::keConstant, CORINFO_Array_MaxLength));
}
}
else if (genActualType(expr) == TYP_INT)
{
// Use GetRangeFromAssertions for everything else since they won't produce dependent or symbolic ranges
range = GetRangeFromAssertions(m_compiler, vn, block->bbAssertionIn);
}
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else
{
// The expression is not recognized, so the result is unknown.
Expand Down
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