[libc-commits] [clang] [libc] [clang] Make __builtin_exp and __builtin_expf constexpr. (PR #199808)

[Timm Baeder via libc-commits]

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@@ -710,6 +711,24 @@ static bool interp__builtin_fpclassify(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_exp(InterpState &S, CodePtr OpPC,
+                                const InterpFrame *Frame,
+                                const CallExpr *Call) {
+  const Floating &Arg = S.Stk.pop<Floating>();
+  FPOptions FPO = Call->getFPFeaturesInEffect(S.Ctx.getLangOpts());
+  llvm::RoundingMode RM = getRoundingMode(FPO);
+  APFloat::opStatus Status;
+  std::optional<APFloat> Result = exp(Arg.getAPFloat(), RM, &Status);
+  // Check for unsupported rounding modes.
+  if (!Result.has_value())
+    return false;
+  // Check for raised non-FE_INEXACT exceptions.
+  if (Status & (~APFloat::opStatus::opInexact))
+    return false;
+  S.Stk.push<Floating>(Floating(*Result));
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tbaederr wrote:

Pretty sure this doesn't work and you need to allocate a new floating via the `InterpState`. See e.g. `interp__builtin_inf`.

https://github.com/llvm/llvm-project/pull/199808