[llvm] [APFloat] Add APFloat support for E8M0 type (PR #107127)

[Durgadoss R via llvm-commits]

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@@ -1106,25 +1129,26 @@ bool IEEEFloat::isSignificandAllZerosExceptMSB() const {
       return false;
   }
 
-  const unsigned NumHighBits =
-      PartCount * integerPartWidth - semantics->precision + 1;
-  return Parts[PartCount - 1] == integerPart(1)
-                                     << (integerPartWidth - NumHighBits);
+  const unsigned NumHighBits = getNumHighBits();
+  const integerPart MSBMask = integerPart(1)
+                              << (integerPartWidth - NumHighBits);
+  return ((semantics->precision <= 1) || (Parts[PartCount - 1] == MSBMask));
 }
 
 bool IEEEFloat::isLargest() const {
+  bool IsMaxExp = isFiniteNonZero() && exponent == semantics->maxExponent;
   if (semantics->nonFiniteBehavior == fltNonfiniteBehavior::NanOnly &&
       semantics->nanEncoding == fltNanEncoding::AllOnes) {
     // The largest number by magnitude in our format will be the floating point
     // number with maximum exponent and with significand that is all ones except
     // the LSB.
-    return isFiniteNonZero() && exponent == semantics->maxExponent &&
-           isSignificandAllOnesExceptLSB();
+    return APFloat::hasSignificand(*semantics)
+               ? (IsMaxExp && isSignificandAllOnesExceptLSB())
+               : IsMaxExp;
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durga4github wrote:

Yes, updated in the latest revision.

Resolving,

https://github.com/llvm/llvm-project/pull/107127