[lldb] Allow division by floating point zero in Scalar (llvm#158115)

`Scalar` produced an invalid value when detecting any division by zero.
This should be only for integer division.

Author: kuilpd

lldb/source/Utility/Scalar.cpp

@@ -565,12 +565,13 @@ const Scalar lldb_private::operator-(Scalar lhs, Scalar rhs) {
 
 const Scalar lldb_private::operator/(Scalar lhs, Scalar rhs) {
   Scalar result;
-  if ((result.m_type = Scalar::PromoteToMaxType(lhs, rhs)) != Scalar::e_void &&
-      !rhs.IsZero()) {
+  if ((result.m_type = Scalar::PromoteToMaxType(lhs, rhs)) != Scalar::e_void) {
     switch (result.m_type) {
     case Scalar::e_void:
       break;
     case Scalar::e_int:
+      if (rhs.IsZero())
+        break;
       result.m_integer = lhs.m_integer / rhs.m_integer;
       return result;
     case Scalar::e_float:

lldb/unittests/Utility/ScalarTest.cpp

@@ -337,6 +337,12 @@ TEST(ScalarTest, Division) {
   Scalar r = lhs / rhs;
   EXPECT_TRUE(r.IsValid());
   EXPECT_EQ(r, Scalar(2.5));
+
+  Scalar inf = Scalar(1) / Scalar(0.0f);
+  Scalar int0 = Scalar(1) / Scalar(0);
+  Scalar ref_inf = llvm::APFloat::getInf(llvm::APFloat::IEEEsingle());
+  EXPECT_EQ(inf, ref_inf);
+  EXPECT_FALSE(int0.IsValid());
 }
 
 TEST(ScalarTest, Promotion) {