[clang] [X86][Clang] VectorExprEvaluator::VisitCallExpr / InterpretBuiltin - Allow SSE/AVX FP MAX/MIN intrinsics to be used in constexpr (PR #171966)

[Timm Baeder via cfe-commits]

================
@@ -2433,6 +2433,46 @@ static bool interp__builtin_elementwise_int_unaryop(
   return true;
 }
 
+static bool interp__builtin_elementwise_fp_binop(
+    InterpState &S, CodePtr OpPC, const CallExpr *Call,
+    llvm::function_ref<APFloat(const APFloat &, const APFloat &,
+                               std::optional<APSInt> RoundingMode)>
+        Fn) {
+  assert((Call->getNumArgs() == 2) || (Call->getNumArgs() == 3));
+  const auto *VT = Call->getArg(0)->getType()->castAs<VectorType>();
+  assert(VT->getElementType()->isFloatingType());
+  unsigned NumElems = VT->getNumElements();
+
+  // Vector case.
+  assert(Call->getArg(0)->getType()->isVectorType() &&
+         Call->getArg(1)->getType()->isVectorType());
+  assert(VT->getElementType() ==
+         Call->getArg(1)->getType()->castAs<VectorType>()->getElementType());
+  assert(VT->getNumElements() ==
+         Call->getArg(1)->getType()->castAs<VectorType>()->getNumElements());
+
+  std::optional<APSInt> RoundingMode = std::nullopt;
+  if (Call->getNumArgs() == 3) {
+    RoundingMode = popToAPSInt(S, Call->getArg(2));
+  }
----------------
tbaederr wrote:

```suggestion
  if (Call->getNumArgs() == 3)
    RoundingMode = popToAPSInt(S, Call->getArg(2));
```

https://github.com/llvm/llvm-project/pull/171966