[llvm] [InstCombine] Avoid crash on aggregate types in SimplifyDemandedUseFPClass (PR #111128)

[Nikita Popov via llvm-commits]

================
@@ -1919,17 +1919,26 @@ Value *InstCombinerImpl::SimplifyDemandedVectorElts(Value *V,
 /// For floating-point classes that resolve to a single bit pattern, return that
 /// value.
 static Constant *getFPClassConstant(Type *Ty, FPClassTest Mask) {
-  switch (Mask) {
-  case fcPosZero:
+  if (Mask == fcNone)
+    return PoisonValue::get(Ty);
+
+  if (Mask == fcPosZero) {
+    if (Ty->isAggregateType())
+      return ConstantAggregateZero::get(Ty);
     return ConstantFP::getZero(Ty);
+  }
----------------
nikic wrote:

```suggestion
  if (Mask == fcPosZero) {
    return Constant::getNullValue(Ty);
```

https://github.com/llvm/llvm-project/pull/111128