[LLDB] Add APFloat helper functions to Scalar class. (#86862)

This adds the ability to create a Scalar from an APFloat, and to create
an APFloat from an APSInt or another APFloat.

Author: cmtice

lldb/include/lldb/Utility/Scalar.h

@@ -71,6 +71,7 @@ class Scalar {
       : m_type(e_int), m_integer(std::move(v), false), m_float(0.0f) {}
   Scalar(llvm::APSInt v)
       : m_type(e_int), m_integer(std::move(v)), m_float(0.0f) {}
+  Scalar(llvm::APFloat v) : m_type(e_float), m_integer(0), m_float(v) {}
 
   bool SignExtend(uint32_t bit_pos);
 
@@ -186,6 +187,10 @@ class Scalar {
   Status SetValueFromData(const DataExtractor &data, lldb::Encoding encoding,
                           size_t byte_size);
 
+  llvm::APFloat CreateAPFloatFromAPSInt(lldb::BasicType basic_type);
+
+  llvm::APFloat CreateAPFloatFromAPFloat(lldb::BasicType basic_type);
+
 protected:
   Scalar::Type m_type = e_void;
   llvm::APSInt m_integer;

lldb/source/Utility/Scalar.cpp

@@ -813,6 +813,48 @@ bool Scalar::ExtractBitfield(uint32_t bit_size, uint32_t bit_offset) {
   return false;
 }
 
+llvm::APFloat Scalar::CreateAPFloatFromAPSInt(lldb::BasicType basic_type) {
+  switch (basic_type) {
+  case lldb::eBasicTypeFloat:
+    return llvm::APFloat(
+        m_integer.isSigned()
+            ? llvm::APIntOps::RoundSignedAPIntToFloat(m_integer)
+            : llvm::APIntOps::RoundAPIntToFloat(m_integer));
+  case lldb::eBasicTypeDouble:
+    // No way to get more precision at the moment.
+  case lldb::eBasicTypeLongDouble:
+    return llvm::APFloat(
+        m_integer.isSigned()
+            ? llvm::APIntOps::RoundSignedAPIntToDouble(m_integer)
+            : llvm::APIntOps::RoundAPIntToDouble(m_integer));
+  default:
+    const llvm::fltSemantics &sem = APFloat::IEEEsingle();
+    return llvm::APFloat::getNaN(sem);
+  }
+}
+
+llvm::APFloat Scalar::CreateAPFloatFromAPFloat(lldb::BasicType basic_type) {
+  switch (basic_type) {
+  case lldb::eBasicTypeFloat: {
+    bool loses_info;
+    m_float.convert(llvm::APFloat::IEEEsingle(),
+                    llvm::APFloat::rmNearestTiesToEven, &loses_info);
+    return m_float;
+  }
+  case lldb::eBasicTypeDouble:
+    // No way to get more precision at the moment.
+  case lldb::eBasicTypeLongDouble: {
+    bool loses_info;
+    m_float.convert(llvm::APFloat::IEEEdouble(),
+                    llvm::APFloat::rmNearestTiesToEven, &loses_info);
+    return m_float;
+  }
+  default:
+    const llvm::fltSemantics &sem = APFloat::IEEEsingle();
+    return llvm::APFloat::getNaN(sem);
+  }
+}
+
 bool lldb_private::operator==(Scalar lhs, Scalar rhs) {
   // If either entry is void then we can just compare the types
   if (lhs.m_type == Scalar::e_void || rhs.m_type == Scalar::e_void)

lldb/unittests/Utility/ScalarTest.cpp

@@ -402,3 +402,61 @@ TEST(ScalarTest, TruncOrExtendTo) {
   S.TruncOrExtendTo(16, false);
   EXPECT_EQ(S.UInt128(APInt()), APInt(16, 0xffffu));
 }
+
+TEST(ScalarTest, APFloatConstructor) {
+  llvm::APFloat my_single(llvm::APFloatBase::IEEEsingle(), "3.14159");
+  llvm::APFloat my_double(llvm::APFloatBase::IEEEdouble(), "3.14159");
+  Scalar S(my_single);
+  Scalar D(my_double);
+
+  EXPECT_EQ(S.GetType(), Scalar::e_float);
+  EXPECT_EQ(D.GetType(), Scalar::e_float);
+  ASSERT_TRUE(S != D);
+}
+
+TEST(ScalarTest, CreateAPFloats) {
+  llvm::APFloat ap_float(llvm::APFloatBase::IEEEsingle(), "3.14159");
+  llvm::APFloat ap_nan = llvm::APFloat::getNaN(llvm::APFloat::IEEEsingle());
+  llvm::APSInt int1("12");
+  llvm::APSInt int2("-4");
+  Scalar I1(int1);
+  Scalar I2(int2);
+  Scalar F(ap_float);
+
+  llvm::APFloat out1_float = I1.CreateAPFloatFromAPSInt(lldb::eBasicTypeFloat);
+  llvm::APFloat out1_double =
+      I1.CreateAPFloatFromAPSInt(lldb::eBasicTypeDouble);
+  llvm::APFloat out1_longdouble =
+      I1.CreateAPFloatFromAPSInt(lldb::eBasicTypeLongDouble);
+  llvm::APFloat out1_nan =
+      I1.CreateAPFloatFromAPSInt(lldb::eBasicTypeFloatComplex);
+  EXPECT_TRUE(!out1_float.isNegative());
+  EXPECT_TRUE(!out1_double.isNegative());
+  EXPECT_TRUE(out1_double.bitwiseIsEqual(out1_longdouble));
+  EXPECT_FALSE(out1_double.bitwiseIsEqual(out1_float));
+  EXPECT_TRUE(out1_nan.bitwiseIsEqual(ap_nan));
+
+  llvm::APFloat out2_float = I2.CreateAPFloatFromAPSInt(lldb::eBasicTypeFloat);
+  llvm::APFloat out2_double =
+      I2.CreateAPFloatFromAPSInt(lldb::eBasicTypeDouble);
+  llvm::APFloat out2_longdouble =
+      I2.CreateAPFloatFromAPSInt(lldb::eBasicTypeLongDouble);
+  llvm::APFloat out2_nan =
+      I2.CreateAPFloatFromAPSInt(lldb::eBasicTypeFloatComplex);
+  EXPECT_TRUE(out2_float.isNegative());
+  EXPECT_TRUE(out2_double.isNegative());
+  EXPECT_TRUE(out2_double.bitwiseIsEqual(out2_longdouble));
+  EXPECT_FALSE(out2_double.bitwiseIsEqual(out2_float));
+  EXPECT_TRUE(out2_nan.bitwiseIsEqual(ap_nan));
+
+  llvm::APFloat out3_float = F.CreateAPFloatFromAPFloat(lldb::eBasicTypeFloat);
+  llvm::APFloat out3_double =
+      F.CreateAPFloatFromAPFloat(lldb::eBasicTypeDouble);
+  llvm::APFloat out3_longdouble =
+      F.CreateAPFloatFromAPFloat(lldb::eBasicTypeLongDouble);
+  llvm::APFloat out3_nan =
+      F.CreateAPFloatFromAPFloat(lldb::eBasicTypeFloatComplex);
+  EXPECT_TRUE(out3_double.bitwiseIsEqual(out3_longdouble));
+  EXPECT_FALSE(out3_double.bitwiseIsEqual(out3_float));
+  EXPECT_TRUE(out3_nan.bitwiseIsEqual(ap_nan));
+}