[libc][math] Fix some mis-optimization issue with hypotf16. (#141960)

Author: lntue

libc/src/math/generic/hypotf16.cpp

@@ -48,10 +48,13 @@ LLVM_LIBC_FUNCTION(float16, hypotf16, (float16 x, float16 y)) {
     return a_bits.get_val();
   }
 
+  // TODO: Investigate why replacing the return line below with:
+  //   return x_bits.get_val() + y_bits.get_val();
+  // fails the hypotf16 smoke tests.
   if (LIBC_UNLIKELY(a_u - b_u >=
                     static_cast<uint16_t>((FPBits::FRACTION_LEN + 2)
                                           << FPBits::FRACTION_LEN)))
-    return x_abs.get_val() + y_abs.get_val();
+    return a_bits.get_val() + b_bits.get_val();
 
   float af = fputil::cast<float>(a_bits.get_val());
   float bf = fputil::cast<float>(b_bits.get_val());