[libc] [llvm] [APFloat] Add exp function for APFloat::IEEESsingle using expf implementation from LLVM libc. (PR #143959)

[Joshua Cranmer via llvm-commits]

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@@ -5601,6 +5606,34 @@ float APFloat::convertToFloat() const {
   return Temp.getIEEE().convertToFloat();
 }
 
+#ifdef LLVM_INTEGRATE_LIBC
+static constexpr int getFEnvRoundingMode(llvm::RoundingMode rm) {
+  switch (rm) {
+  case APFloat::rmTowardPositive:
+    return FE_UPWARD;
+  case APFloat::rmTowardNegative:
+    return FE_DOWNWARD;
+  case APFloat::rmTowardZero:
+    return FE_TOWARDZERO;
+  default:
+    // TODO: fix rmNearestTiesToAway for platform without FE_TONEARESTFROMZERO.
+    return FE_TONEAREST;
+  };
+}
+
+APFloat exp(const APFloat &X,
+            RoundingMode rounding_mode = APFloat::rmNearestTiesToEven) {
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jcranmer-intel wrote:

... and the default parameter is only in the definition body that no user code sees.

https://github.com/llvm/llvm-project/pull/143959