[libc][math][c23] Update for comments.

Author: harrisonGPU

libc/config/linux/riscv/entrypoints.txt

@@ -397,7 +397,6 @@ set(TARGET_LIBM_ENTRYPOINTS
     # math.h entrypoints
     libc.src.math.acosf
     libc.src.math.acoshf
-    libc.src.math.acoshf16
     libc.src.math.asinf
     libc.src.math.asinhf
     libc.src.math.atan2

libc/src/math/generic/CMakeLists.txt

@@ -3955,6 +3955,7 @@ add_entrypoint_object(
     libc.hdr.errno_macros
     libc.hdr.fenv_macros
     libc.src.__support.FPUtil.cast
+    libc.src.__support.FPUtil.except_value_utils
     libc.src.__support.FPUtil.fenv_impl
     libc.src.__support.FPUtil.fp_bits
     libc.src.__support.FPUtil.multiply_add

libc/src/math/generic/acoshf16.cpp

@@ -12,10 +12,13 @@
 #include "hdr/fenv_macros.h"
 #include "src/__support/FPUtil/FEnvImpl.h"
 #include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
 #include "src/__support/FPUtil/cast.h"
 #include "src/__support/FPUtil/except_value_utils.h"
 #include "src/__support/FPUtil/multiply_add.h"
 #include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
 #include "src/__support/macros/optimization.h"
 
 namespace LIBC_NAMESPACE_DECL {
@@ -34,15 +37,6 @@ LLVM_LIBC_FUNCTION(float16, acoshf16, (float16 x)) {
   FPBits xbits(x);
   uint16_t x_u = xbits.uintval();
 
-  // Domain error for inputs less than 1.0.
-  if (LIBC_UNLIKELY(x <= 1.0f)) {
-    if (x == 1.0f)
-      return FPBits::zero().get_val();
-    fputil::set_errno_if_required(EDOM);
-    fputil::raise_except_if_required(FE_INVALID);
-    return FPBits::quiet_nan().get_val();
-  }
-
   // Check for NaN input first.
   if (LIBC_UNLIKELY(xbits.is_inf_or_nan())) {
     if (xbits.is_signaling_nan()) {
@@ -57,6 +51,15 @@ LLVM_LIBC_FUNCTION(float16, acoshf16, (float16 x)) {
     return x;
   }
 
+  // Domain error for inputs less than 1.0.
+  if (LIBC_UNLIKELY(x <= 1.0f)) {
+    if (x == 1.0f)
+      return FPBits::zero().get_val();
+    fputil::set_errno_if_required(EDOM);
+    fputil::raise_except_if_required(FE_INVALID);
+    return FPBits::quiet_nan().get_val();
+  }
+
   if (auto r = ACOSHF16_EXCEPTS.lookup(xbits.uintval());
       LIBC_UNLIKELY(r.has_value()))
     return r.value();