[clang] [llvm] [C++23] [CLANG] Adding C++23 constexpr math functions: fmin, fmax and frexp. (PR #88978)

[Joshua Cranmer via llvm-commits]

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@@ -14674,6 +14676,31 @@ static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
 
   return true;
 }
+//  Checks that the value x is in the range (-1;-0.5], [0.5; 1)
+static bool isInFrexpResultRange(const llvm::APFloat &x) {
+  llvm::APFloat minusOne(x.getSemantics(), "-1.0");
+  llvm::APFloat minusHalf(x.getSemantics(), "-0.5");
+  llvm::APFloat half(x.getSemantics(), "0.5");
+  llvm::APFloat one(x.getSemantics(), "1.0");
+
+  return ((x.compare(minusOne) == llvm::APFloat::cmpGreaterThan &&
+           x.compare(minusHalf) != llvm::APFloat::cmpGreaterThan) ||
+          (x.compare(half) != llvm::APFloat::cmpLessThan &&
+           x.compare(one) == llvm::APFloat::cmpLessThan));
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jcranmer-intel wrote:

You can simplify this by checking that the absolute value is in [0.5, 1)

https://github.com/llvm/llvm-project/pull/88978