[clang][Interp] Fix comparing nan/inf floating point values

[cor3ntin]

LGTM

clang/lib/AST/Interp/Floating.h

public:
   bool isZero() const { return F.isZero(); }
   bool isNonZero() const { return F.isNonZero(); }
   bool isMin() const { return F.isSmallest(); }
   bool isMinusOne() const { return F.isExactlyValue(-1.0); }
   bool isNan() const { return F.isNaN(); }
   bool isFinite() const { return F.isFinite(); }
 
   ComparisonCategoryResult compare(const Floating &RHS) const {
-    return Compare(F, RHS.F);
+    llvm::APFloatBase::cmpResult CmpRes = F.compare(RHS.F);
+    switch (CmpRes) {
+    case llvm::APFloatBase::cmpLessThan:
+      return ComparisonCategoryResult::Less;
+    case llvm::APFloatBase::cmpEqual:
+      return ComparisonCategoryResult::Equal;
+    case llvm::APFloatBase::cmpGreaterThan:
+      return ComparisonCategoryResult::Greater;
+    case llvm::APFloatBase::cmpUnordered:
+      return ComparisonCategoryResult::Unordered;
+    }
+    llvm_unreachable("Inavlid cmpResult value");
   }
 
   static APFloat::opStatus fromIntegral(APSInt Val,
                                         const llvm::fltSemantics &Sem,
                                         llvm::RoundingMode RM,
                                         Floating &Result) {
     APFloat F = APFloat(Sem);
     APFloat::opStatus Status = F.convertFromAPInt(Val, Val.isSigned(), RM);

clang/test/AST/Interp/floats.cpp

namespace ZeroInit {
 
   constexpr A<double> b{12};
   static_assert(a.f == 0.0, "");
 };
 
 namespace LongDouble {
   constexpr long double ld = 3.1425926539;
 }
+
+namespace Compare {
+  constexpr float nan = __builtin_nan("");
+  constexpr float inf = __builtin_inf();
+  static_assert(!(nan == nan), "");
+  static_assert(nan != nan, "");
+  static_assert(!(inf < nan), "");
+  static_assert(!(inf > nan), "");
+}