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8361037: [ubsan] compiler/c2/irTests/TestFloat16ScalarOperations division by 0

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Reviewed-by: mhaessig, sviswanathan
This commit is contained in:
Jatin Bhateja 2025-07-03 08:03:55 +00:00
parent c75df634be
commit 2f683fdc4a
1 changed files with 23 additions and 0 deletions
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23
src/hotspot/share/opto/divnode.cpp
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@ -825,6 +825,29 @@ const Type* DivHFNode::Value(PhaseGVN* phase) const {
if (t1->base() == Type::HalfFloatCon &&
t2->base() == Type::HalfFloatCon) {
// IEEE 754 floating point comparison treats 0.0 and -0.0 as equals.
// Division of a zero by a zero results in NaN.
if (t1->getf() == 0.0f && t2->getf() == 0.0f) {
return TypeH::make(NAN);
}
// As per C++ standard section 7.6.5 (expr.mul), behavior is undefined only if
// the second operand is 0.0. In all other situations, we can expect a standard-compliant
// C++ compiler to generate code following IEEE 754 semantics.
if (t2->getf() == 0.0) {
// If either operand is NaN, the result is NaN
if (g_isnan(t1->getf())) {
return TypeH::make(NAN);
} else {
// Division of a nonzero finite value by a zero results in a signed infinity. Also,
// division of an infinity by a finite value results in a signed infinity.
bool res_sign_neg = (jint_cast(t1->getf()) < 0) ^ (jint_cast(t2->getf()) < 0);
const TypeF* res = res_sign_neg ? TypeF::NEG_INF : TypeF::POS_INF;
return TypeH::make(res->getf());
}
}
return TypeH::make(t1->getf() / t2->getf());
}