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Fix potential fgIsBigOffset issue in optAssertionIsNonNull #124289

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Fix potential fgIsBigOffset issue in optAssertionIsNonNull #124289

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104 changes: 56 additions & 48 deletions src/coreclr/jit/assertionprop.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4556,62 +4556,22 @@ GenTree* Compiler::optAssertionProp_Ind(ASSERT_VALARG_TP assertions, GenTree* tr
//
bool Compiler::optAssertionIsNonNull(GenTree* op, ASSERT_VALARG_TP assertions)
{
if (op->OperIs(GT_ADD) && op->AsOp()->gtGetOp2()->IsCnsIntOrI() &&
!fgIsBigOffset(op->AsOp()->gtGetOp2()->AsIntCon()->IconValue()))
{
op = op->AsOp()->gtGetOp1();
}

// Fast path when we have a VN
if (!optLocalAssertionProp && vnStore->IsKnownNonNull(op->gtVNPair.GetConservative()))
{
return true;
}

if (!optCanPropNonNull || BitVecOps::MayBeUninit(assertions))
{
return false;
}

op = op->gtEffectiveVal();
if (!op->OperIs(GT_LCL_VAR))
{
return false;
}

// If local assertion prop use lcl comparison, else use VN comparison.
if (!optLocalAssertionProp)
// Local assertion prop
//
if (optLocalAssertionProp)
{
// Look at both the top-level vn, and
// the vn we get by stripping off any constant adds.
//
ValueNum vn = vnStore->VNConservativeNormalValue(op->gtVNPair);
if (vn == ValueNumStore::NoVN)
if (!optCanPropNonNull || BitVecOps::MayBeUninit(assertions))
{
return false;
}

ValueNum vnBase = vn;
target_ssize_t offset = 0;
vnStore->PeelOffsets(&vnBase, &offset);

// Check each assertion to find if we have a vn != null assertion.
//
BitVecOps::Iter iter(apTraits, assertions);
unsigned index = 0;
while (iter.NextElem(&index))
gtPeelOffsets(&op, &offset);
if (fgIsBigOffset(offset) || !op->OperIs(GT_LCL_VAR))
{
AssertionIndex assertionIndex = GetAssertionIndex(index);
const AssertionDsc& curAssertion = optGetAssertion(assertionIndex);
if (curAssertion.CanPropNonNull() &&
((curAssertion.GetOp1().GetVN() == vn) || (curAssertion.GetOp1().GetVN() == vnBase)))
{
return true;
}
return false;
}
}
else
{

// Find live assertions related to lclNum
//
unsigned const lclNum = op->AsLclVarCommon()->GetLclNum();
Expand All @@ -4634,6 +4594,54 @@ bool Compiler::optAssertionIsNonNull(GenTree* op, ASSERT_VALARG_TP assertions)
return true;
}
}
return false;
}

// Global assertion prop
//
assert(!optLocalAssertionProp);

ValueNum vn = optConservativeNormalVN(op);
if (vn == ValueNumStore::NoVN)
{
return false;
}

// Check VN and base address for null if the offset is within the valid threshold.
ValueNum vnBase = vn;
target_ssize_t offset = 0;
vnStore->PeelOffsets(&vnBase, &offset);
if (fgIsBigOffset(offset))
{
vnBase = vn;
}

// Unlike Local AP, for Global AP we focus on GC nulls (VNForNull).
// Relaxing this check may slightly improve coverage but risks a TP regression
if (!varTypeIsGC(vnStore->TypeOfVN(vn)))
{
return false;
}

if (vnStore->IsKnownNonNull(vnBase))
{
return true;
}

if (optCanPropNonNull && !BitVecOps::MayBeUninit(assertions))
{
BitVecOps::Iter iter(apTraits, assertions);
unsigned index = 0;
while (iter.NextElem(&index))
{
AssertionIndex assertionIndex = GetAssertionIndex(index);
const AssertionDsc& curAssertion = optGetAssertion(assertionIndex);
if (curAssertion.CanPropNonNull() &&
((curAssertion.GetOp1().GetVN() == vn) || (curAssertion.GetOp1().GetVN() == vnBase)))
{
return true;
}
}
}
return false;
}
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