[APFloat][NFC]extract fltSemantics::isRepresentableBy to header (#122636)

isRepresentableBy is useful to check float point type compatibility

Author: HerrCai0907

llvm/include/llvm/ADT/APFloat.h

@@ -281,6 +281,11 @@ struct APFloatBase {
   /// anything real.
   static const fltSemantics &Bogus() LLVM_READNONE;
 
+  // Returns true if any number described by this semantics can be precisely
+  // represented by the specified semantics. Does not take into account
+  // the value of fltNonfiniteBehavior, hasZero, hasSignedRepr.
+  static bool isRepresentableBy(const fltSemantics &A, const fltSemantics &B);
+
   /// @}
 
   /// IEEE-754R 5.11: Floating Point Comparison Relations.

llvm/lib/Support/APFloat.cpp

@@ -125,14 +125,6 @@ struct fltSemantics {
 
   /* Whether this semantics can represent signed values */
   bool hasSignedRepr = true;
-
-  // Returns true if any number described by this semantics can be precisely
-  // represented by the specified semantics. Does not take into account
-  // the value of fltNonfiniteBehavior.
-  bool isRepresentableBy(const fltSemantics &S) const {
-    return maxExponent <= S.maxExponent && minExponent >= S.minExponent &&
-           precision <= S.precision;
-  }
 };
 
 static constexpr fltSemantics semIEEEhalf = {15, -14, 11, 16};
@@ -290,6 +282,12 @@ const fltSemantics &APFloatBase::x87DoubleExtended() {
 }
 const fltSemantics &APFloatBase::Bogus() { return semBogus; }
 
+bool APFloatBase::isRepresentableBy(const fltSemantics &A,
+                                    const fltSemantics &B) {
+  return A.maxExponent <= B.maxExponent && A.minExponent >= B.minExponent &&
+         A.precision <= B.precision;
+}
+
 constexpr RoundingMode APFloatBase::rmNearestTiesToEven;
 constexpr RoundingMode APFloatBase::rmTowardPositive;
 constexpr RoundingMode APFloatBase::rmTowardNegative;
@@ -5527,7 +5525,7 @@ APFloat::opStatus APFloat::convertToInteger(APSInt &result,
 double APFloat::convertToDouble() const {
   if (&getSemantics() == (const llvm::fltSemantics *)&semIEEEdouble)
     return getIEEE().convertToDouble();
-  assert(getSemantics().isRepresentableBy(semIEEEdouble) &&
+  assert(isRepresentableBy(getSemantics(), semIEEEdouble) &&
          "Float semantics is not representable by IEEEdouble");
   APFloat Temp = *this;
   bool LosesInfo;
@@ -5541,7 +5539,7 @@ double APFloat::convertToDouble() const {
 float128 APFloat::convertToQuad() const {
   if (&getSemantics() == (const llvm::fltSemantics *)&semIEEEquad)
     return getIEEE().convertToQuad();
-  assert(getSemantics().isRepresentableBy(semIEEEquad) &&
+  assert(isRepresentableBy(getSemantics(), semIEEEquad) &&
          "Float semantics is not representable by IEEEquad");
   APFloat Temp = *this;
   bool LosesInfo;
@@ -5555,7 +5553,7 @@ float128 APFloat::convertToQuad() const {
 float APFloat::convertToFloat() const {
   if (&getSemantics() == (const llvm::fltSemantics *)&semIEEEsingle)
     return getIEEE().convertToFloat();
-  assert(getSemantics().isRepresentableBy(semIEEEsingle) &&
+  assert(isRepresentableBy(getSemantics(), semIEEEsingle) &&
          "Float semantics is not representable by IEEEsingle");
   APFloat Temp = *this;
   bool LosesInfo;