[libc-commits] [libc] [llvm] [libc][math] Added missing floating point exception for atanpif16 (PR #186597)

[via libc-commits]

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@@ -119,14 +113,34 @@ LLVM_LIBC_FUNCTION(float16, atanpif16, (float16 x)) {
 
   // Case 1: |x| <= 0.5 - Direct polynomial evaluation
   if (LIBC_LIKELY(x_abs <= 0.5)) {
+
+    if (LIBC_UNLIKELY(xbits.is_zero()))
+      return x;
+
+    if (LIBC_UNLIKELY(xbits.uintval() == 0x0a48 || xbits.uintval() == 0x8a48)) {
+      int rounding = fputil::quick_get_round();
+
+      if (rounding == FE_UPWARD && xbits.uintval() == 0x0a48)
+        return fputil::FPBits<float16>(uint16_t(0x0400)).get_val();
+
+      if (rounding == FE_DOWNWARD && xbits.uintval() == 0x8a48)
+        return fputil::FPBits<float16>(uint16_t(0x8400)).get_val();
+    }
+
     double result = atanpi_eval(x_abs);
-    return signed_result(result);
+    float16 s_result = signed_result(result);
+    if (FPBits(s_result).is_subnormal())
+      fputil::raise_except_if_required(FE_UNDERFLOW);
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lntue wrote:

`fputil::float_cast` does not raise underflow exception?


https://github.com/llvm/llvm-project/pull/186597