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JIT: Extend non-null assertion propagation to pointer-sized comparisons #134744

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Merged
EgorBo merged 2 commits into from
Sep 28, 2026
Merged

JIT: Extend non-null assertion propagation to pointer-sized comparisons #134744

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2e82d61
JIT: Extend non-null assertion propagation to pointer-sized comparisons
EgorBo Sep 27, 2026
4a062ab
JIT: Guard non-null assertion propagation by VN type
EgorBo Sep 27, 2026
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17 changes: 5 additions & 12 deletions src/coreclr/jit/assertionprop.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4691,19 +4691,12 @@ GenTree* Compiler::optAssertionPropGlobal_RelOp(ASSERT_VALARG_TP assertions,
return nullptr;
}

// See if we have "PHI ==/!= null" tree. If so, we iterate over all PHI's arguments,
// and if all of them are known to be non-null, we can bash the comparison to true/false.
if (op2->IsIntegralConst(0) && op1->TypeIs(TYP_REF))
// Use non-null assertions for the address or its base, including across PHIs.
if (op2->IsIntegralConst(0) && varTypeIsI(op1))
{
JITDUMP("Checking PHI [%06u] arguments for non-nullness\n", dspTreeID(op1))
auto visitor = [this](ValueNum reachingVN, ASSERT_TP reachingAssertions) {
return optAssertionVNIsNonNull(reachingVN, reachingAssertions) ? AssertVisit::Continue : AssertVisit::Abort;
};

ValueNum op1vn = vnStore->VNConservativeNormalValue(op1->gtVNPair);
if (optVisitReachingAssertions(op1vn, visitor) == AssertVisit::Continue)
if (optAssertionVNIsNonNull(op1VN, assertions))
{
JITDUMP("... all of PHI's arguments are never null!\n");
JITDUMP("Proved [%06u] non-null\n", dspTreeID(op1));
assert(newTree->OperIs(GT_EQ, GT_NE));
newTree = tree->OperIs(GT_EQ) ? gtNewIconNode(0) : gtNewIconNode(1);
return optAssertionProp_Update(newTree, tree, stmt);
Expand Down Expand Up @@ -5277,7 +5270,7 @@ bool Compiler::optAssertionIsNonNull(GenTree* op, ASSERT_VALARG_TP assertions)
//
bool Compiler::optAssertionVNIsNonNull(ValueNum vn, ASSERT_VALARG_TP assertions, int budget)
{
if (vn == ValueNumStore::NoVN)
if ((vn == ValueNumStore::NoVN) || !varTypeIsI(vnStore->TypeOfVN(vn)))
{
return false;
}
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