[libc][math] Refactor frexpf16 implementation to header-only in src/__support/math folder. (#147889)

Part of #147386

in preparation for:
https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450

Author: bassiounix

libc/shared/math.h

@@ -14,5 +14,6 @@
 #include "math/expf.h"
 #include "math/expf16.h"
 #include "math/frexpf128.h"
+#include "math/frexpf16.h"
 
 #endif // LLVM_LIBC_SHARED_MATH_H

libc/shared/math/frexpf16.h

@@ -0,0 +1,29 @@
+//===-- Shared frexpf16 function --------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SHARED_MATH_FREXPF16_H
+#define LLVM_LIBC_SHARED_MATH_FREXPF16_H
+
+#include "include/llvm-libc-macros/float16-macros.h"
+#include "shared/libc_common.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "src/__support/math/frexpf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::frexpf16;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+
+#endif // LLVM_LIBC_SHARED_MATH_FREXPF16_H

libc/src/__support/math/CMakeLists.txt

@@ -64,3 +64,13 @@ add_header_library(
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.manipulation_functions
 )
+
+add_header_library(
+  frexpf16
+  HDRS
+    frexpf16.h
+  DEPENDS
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+)

libc/src/__support/math/frexpf16.h

@@ -0,0 +1,34 @@
+//===-- Implementation header for frexpf16 ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_FREXPF16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_FREXPF16_H
+
+#include "include/llvm-libc-macros/float16-macros.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+static constexpr float16 frexpf16(float16 x, int *exp) {
+  return fputil::frexp(x, *exp);
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_FREXPF16_H

libc/src/math/generic/CMakeLists.txt

@@ -1779,8 +1779,7 @@ add_entrypoint_object(
   HDRS
     ../frexpf16.h
   DEPENDS
-    libc.src.__support.macros.properties.types
-    libc.src.__support.FPUtil.manipulation_functions
+    libc.src.__support.math.frexpf16
 )
 
 add_entrypoint_object(

libc/src/math/generic/frexpf16.cpp

@@ -7,14 +7,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/frexpf16.h"
-#include "src/__support/FPUtil/ManipulationFunctions.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/config.h"
+
+#include "src/__support/math/frexpf16.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(float16, frexpf16, (float16 x, int *exp)) {
-  return fputil::frexp(x, *exp);
+  return math::frexpf16(x, exp);
 }
 
 } // namespace LIBC_NAMESPACE_DECL

utils/bazel/llvm-project-overlay/libc/BUILD.bazel

@@ -2158,6 +2158,17 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_frexpf16",
+    hdrs = ["src/__support/math/frexpf16.h"],
+    deps = [
+        ":__support_macros_config",
+        ":__support_macros_properties_types",
+        ":__support_fputil_manipulation_functions",
+        ":llvm_libc_macros_float16_macros"
+    ],
+)
+
 ############################### complex targets ################################
 
 libc_function(
@@ -3216,7 +3227,12 @@ libc_math_function(
     ]
 )
 
-libc_math_function(name = "frexpf16")
+libc_math_function(
+    name = "frexpf16",
+    additional_deps = [
+        ":__support_math_frexpf16"
+    ],
+)
 
 libc_math_function(name = "fromfp")