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

[Aaron Ballman via llvm-commits]

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@@ -14574,9 +14574,17 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
   default:
     return false;
 
+  case Builtin::BI__builtin_frexpl:
+    // AIX library function `frexpl` has 'long double' type and not
+    // PPCDoubleDouble type. To make sure we generate the right value, don't
+    // constant evaluate it and instead defer to a libcall.
+    if (Info.Ctx.getTargetInfo().getTriple().isPPC() &&
+        (&Info.Ctx.getTargetInfo().getLongDoubleFormat() !=
+         &llvm::APFloat::PPCDoubleDouble()))
+      return false;
+    LLVM_FALLTHROUGH;
   case Builtin::BI__builtin_frexp:
-  case Builtin::BI__builtin_frexpf:
-  case Builtin::BI__builtin_frexpl: {
+  case Builtin::BI__builtin_frexpf: {
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AaronBallman wrote:

> For compile-time evaluation, the APFloats associated with long double on AIX have the IEEE double format (and the evaluation works fine).

Does the evaluation produce the same results as would happen at runtime despite the different format?

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