[APFloat] Add APFloat::format

llvm/include/llvm/ADT/APFloat.h

@@ -18,7 +18,9 @@
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/FloatingPointMode.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/NativeFormatting.h"
 #include "llvm/Support/float128.h"
 #include <memory>
 
@@ -557,6 +559,15 @@ class IEEEFloat final : public APFloatBase {
 
   cmpResult compareAbsoluteValue(const IEEEFloat &) const;
 
+  /// returns the exponent in the format's radix
+  ExponentType getExponent() const;
+
+  /// returns the significand
+  APInt getSignificand() const;
+
+  /// decompose to an integer and exponent to radix 2
+  bool decomposeToIntegerAndPowerOf2(APInt &, int &) const;
+
 private:
   /// \name Simple Queries
   /// @{
@@ -784,6 +795,8 @@ class DoubleAPFloat final : public APFloatBase {
 
   bool getExactInverse(APFloat *inv) const;
 
+  bool decomposeToIntegerAndPowerOf2(APInt &, int &) const;
+
   LLVM_READONLY
   int getExactLog2() const;
   LLVM_READONLY
@@ -1381,6 +1394,20 @@ class APFloat : public APFloatBase {
         toString(Str, FormatPrecision, FormatMaxPadding, TruncateZero));
   }
 
+  /// Decomposes the value to an integer and an exponent such that
+  /// value = I * 2^exp
+  /// returns true on success, false otherwise (e.g., NaN, Infinity)
+  /// similar to the standard modf, but exponent does not
+  /// have to have the same sign as the value.
+  bool decomposeToIntegerAndPowerOf2(APInt &I, int &exp) const {
+    APFLOAT_DISPATCH_ON_SEMANTICS(decomposeToIntegerAndPowerOf2(I, exp));
+  }
+
+  SmallVectorImpl<char> &
+  format(SmallVectorImpl<char> &strout,
+         llvm::FloatStyle style = llvm::FloatStyle::Exponent,
+         std::optional<size_t> precision = std::nullopt);
+
   void print(raw_ostream &) const;
   void dump() const;