[libc-commits] [libc] [libc] `FPRep` builders return `FPRep` instead of raw `StorageType` (PR #78588)

[Guillaume Chatelet via libc-commits]

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@@ -535,92 +472,178 @@ struct FPRep<FPType::X86_Binary80> : public FPRepBase<FPType::X86_Binary80> {
     // - Quiet Not a Number
     // - Unnormal
     // This can be reduced to the following logic:
-    if (exp_bits() == encode(BiasedExponent::BITS_ALL_ONES()))
+    if (exp_bits() == encode(BiasedExp::BITS_ALL_ONES()))
       return !is_inf();
-    if (exp_bits() != encode(BiasedExponent::BITS_ALL_ZEROES()))
-      return (sig_bits() & encode(Significand::MSB())) == 0;
+    if (exp_bits() != encode(BiasedExp::BITS_ALL_ZEROES()))
+      return (sig_bits() & encode(Sig::MSB())) == 0;
     return false;
   }
   LIBC_INLINE constexpr bool is_quiet_nan() const {
     return exp_sig_bits() >=
-           encode(BiasedExponent::BITS_ALL_ONES(),
-                  Significand::MSB() | (Significand::MSB() >> 1));
+           encode(BiasedExp::BITS_ALL_ONES(), Sig::MSB() | (Sig::MSB() >> 1));
   }
   LIBC_INLINE constexpr bool is_signaling_nan() const {
     return is_nan() && !is_quiet_nan();
   }
   LIBC_INLINE constexpr bool is_inf() const {
-    return exp_sig_bits() ==
-           encode(BiasedExponent::BITS_ALL_ONES(), Significand::MSB());
-  }
-  LIBC_INLINE constexpr bool is_zero() const {
-    return exp_sig_bits() ==
-           encode(BiasedExponent::BITS_ALL_ZEROES(), Significand::ZERO());
+    return exp_sig_bits() == encode(BiasedExp::BITS_ALL_ONES(), Sig::MSB());
   }
   LIBC_INLINE constexpr bool is_finite() const {
     return !is_inf() && !is_nan();
   }
   LIBC_INLINE
   constexpr bool is_subnormal() const {
-    return exp_sig_bits() >
-           encode(BiasedExponent::BITS_ALL_ZEROES(), Significand::ZERO());
+    return exp_bits() == encode(BiasedExp::BITS_ALL_ZEROES());
   }
   LIBC_INLINE constexpr bool is_normal() const {
     const auto exp = exp_bits();
-    if (exp == encode(BiasedExponent::BITS_ALL_ZEROES()) ||
-        exp == encode(BiasedExponent::BITS_ALL_ONES()))
+    if (exp == encode(BiasedExp::BITS_ALL_ZEROES()) ||
+        exp == encode(BiasedExp::BITS_ALL_ONES()))
       return false;
     return get_implicit_bit();
   }
+  LIBC_INLINE constexpr StorageType get_explicit_mantissa() const {
+    return sig_bits();
+  }
 
-  LIBC_INLINE static constexpr FPRep zero(Sign sign = Sign::POS) {
-    return encode(sign, BiasedExponent::BITS_ALL_ZEROES(), Significand::ZERO());
+  // This functions is specific to FPRepSem<FPType::X86_Binary80>.
+  // TODO: Remove if possible.
+  LIBC_INLINE constexpr bool get_implicit_bit() const {
+    return static_cast<bool>(bits & EXPLICIT_BIT_MASK);
   }
-  LIBC_INLINE static constexpr FPRep one(Sign sign = Sign::POS) {
-    return encode(sign, Exponent::ZERO(), Significand::MSB());
+
+  // This functions is specific to FPRepSem<FPType::X86_Binary80>.
+  // TODO: Remove if possible.
+  LIBC_INLINE constexpr void set_implicit_bit(bool implicitVal) {
+    if (get_implicit_bit() != implicitVal)
+      bits ^= EXPLICIT_BIT_MASK;
   }
-  LIBC_INLINE static constexpr FPRep min_subnormal(Sign sign = Sign::POS) {
-    return encode(sign, BiasedExponent::BITS_ALL_ZEROES(), Significand::LSB());
+};
+
+// 'FPRep' is the bottom of the class hierarchy that only deals with 'FPType'.
+// The operations dealing with specific float semantics are implemented by
+// 'FPRepSem' above and specialized when needed.
+//
+// 'RetT' is the return type used by the builders. If not specified it defaults
+// to the 'StorageType' but 'FPBits' class below defaults it to itself so
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gchatelet wrote:

Changed, let me know if it's better.

https://github.com/llvm/llvm-project/pull/78588