Introduce a few new literal conversion functions for various floating point types

PiperOrigin-RevId: 291720187
Change-Id: I07cded6d91eb6aa9101a01705108ab33d68e7d78

tensorflow/compiler/xla/literal_util.cc

@@ -93,16 +93,31 @@ Literal ConvertType(LiteralSlice literal) {
   return ConvertType<bfloat16, float>(bf16_literal);
 }
 
+/* static */ Literal LiteralUtil::ConvertBF16ToF64(
+    const LiteralSlice& bf16_literal) {
+  return ConvertType<bfloat16, double>(bf16_literal);
+}
+
 /* static */ Literal LiteralUtil::ConvertF32ToBF16(
     const LiteralSlice& f32_literal) {
   return ConvertType<float, bfloat16>(f32_literal);
 }
 
+/* static */ Literal LiteralUtil::ConvertF32ToF64(
+    const LiteralSlice& f32_literal) {
+  return ConvertType<float, double>(f32_literal);
+}
+
 /* static */ Literal LiteralUtil::ConvertF64ToBF16(
     const LiteralSlice& f64_literal) {
   return ConvertType<double, bfloat16>(f64_literal);
 }
 
+/* static */ Literal LiteralUtil::ConvertF64ToF32(
+    const LiteralSlice& f64_literal) {
+  return ConvertType<double, float>(f64_literal);
+}
+
 /* static */ Literal LiteralUtil::CreateToken() {
   return Literal(ShapeUtil::MakeTokenShape());
 }

tensorflow/compiler/xla/literal_util.h

@@ -218,16 +218,31 @@ class LiteralUtil {
   // recursively converts its elements.
   static Literal ConvertBF16ToF32(const LiteralSlice& bf16_literal);
 
+  // If the given literal's data type is bfloat16, converts it to a double
+  // literal; otherwise, returns a copy of it. If the literal is a tuple,
+  // recursively converts its elements.
+  static Literal ConvertBF16ToF64(const LiteralSlice& bf16_literal);
+
   // If the given literal's data type is float, converts it to a bfloat16
   // literal; otherwise, returns a copy of it. If the literal is a tuple,
   // recursively converts its elements.
   static Literal ConvertF32ToBF16(const LiteralSlice& f32_literal);
 
+  // If the given literal's data type is float, converts it to a double
+  // literal; otherwise, returns a copy of it. If the literal is a tuple,
+  // recursively converts its elements.
+  static Literal ConvertF32ToF64(const LiteralSlice& f32_literal);
+
   // If the given literal's data type is double, converts it to a bfloat16
   // literal; otherwise, returns a copy of it. If the literal is a tuple,
   // recursively converts its elements.
   static Literal ConvertF64ToBF16(const LiteralSlice& f64_literal);
 
+  // If the given literal's data type is double, converts it to a bfloat16
+  // literal; otherwise, returns a copy of it. If the literal is a tuple,
+  // recursively converts its elements.
+  static Literal ConvertF64ToF32(const LiteralSlice& f64_literal);
+
   // Creates a literal with a new shape with the given new dimensions using the
   // data in the given input literal. For reshaping purposes the (flat) data
   // buffer of the input literal is assumed to have the given minor_to_major