[libc] [llvm] [libc][math] Refactor ldexpf implementation to header-only in src/__support/math folder (PR #147906)

[Muhammad Bassiouni via llvm-commits]

https://github.com/bassiounix created https://github.com/llvm/llvm-project/pull/147906

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

@lntue 

>From 544ac4ddbcd83be76c70d5218c92ba345020be12 Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Thu, 10 Jul 2025 10:26:02 +0300
Subject: [PATCH] [libc][math] Refactor ldexpf implementation to header-only in
 src/__support/math folder

---
 libc/shared/math.h                            |  1 +
 libc/shared/math/ldexpf.h                     | 23 +++++++++++++++
 libc/src/__support/math/CMakeLists.txt        |  8 ++++++
 libc/src/__support/math/ldexpf.h              | 28 +++++++++++++++++++
 libc/src/math/generic/CMakeLists.txt          |  2 +-
 libc/src/math/generic/ldexpf.cpp              |  6 ++--
 .../llvm-project-overlay/libc/BUILD.bazel     | 15 +++++++++-
 7 files changed, 77 insertions(+), 6 deletions(-)
 create mode 100644 libc/shared/math/ldexpf.h
 create mode 100644 libc/src/__support/math/ldexpf.h

diff --git a/libc/shared/math.h b/libc/shared/math.h
index 4ddc29c7ae834..50ae0e1581744 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -12,5 +12,6 @@
 #include "libc_common.h"
 
 #include "math/expf.h"
+#include "math/ldexpf.h"
 
 #endif // LLVM_LIBC_SHARED_MATH_H
diff --git a/libc/shared/math/ldexpf.h b/libc/shared/math/ldexpf.h
new file mode 100644
index 0000000000000..497933c47321f
--- /dev/null
+++ b/libc/shared/math/ldexpf.h
@@ -0,0 +1,23 @@
+//===-- Shared ldexpf 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_LDEXPF_H
+#define LLVM_LIBC_SHARED_MATH_LDEXPF_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/ldexpf.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::ldexpf;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_LDEXPF_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 66c1d19a1cab0..49ab6220919de 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -22,3 +22,11 @@ add_header_library(
     libc.src.__support.macros.config
     libc.src.__support.macros.optimization
 )
+
+add_header_library(
+  ldexpf
+  HDRS
+    ldexpf.h
+  DEPENDS
+    libc.src.__support.FPUtil.manipulation_functions
+)
diff --git a/libc/src/__support/math/ldexpf.h b/libc/src/__support/math/ldexpf.h
new file mode 100644
index 0000000000000..3a5ec1d471337
--- /dev/null
+++ b/libc/src/__support/math/ldexpf.h
@@ -0,0 +1,28 @@
+//===-- Implementation header for ldexpf ------------------------*- 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_LDEXPF_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_LDEXPF_H
+
+#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 float ldexpf(float x, int exp) {
+  return fputil::ldexp(x, exp);
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_LDEXPF_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index fd1e6c0d648aa..4a0f585d1f52d 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -1911,7 +1911,7 @@ add_entrypoint_object(
   HDRS
     ../ldexpf.h
   DEPENDS
-    libc.src.__support.FPUtil.manipulation_functions
+    libc.src.__support.math.ldexpf
 )
 
 add_entrypoint_object(
diff --git a/libc/src/math/generic/ldexpf.cpp b/libc/src/math/generic/ldexpf.cpp
index 63c5d219f7a79..c5f30bb725e6b 100644
--- a/libc/src/math/generic/ldexpf.cpp
+++ b/libc/src/math/generic/ldexpf.cpp
@@ -7,14 +7,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/ldexpf.h"
-#include "src/__support/FPUtil/ManipulationFunctions.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/config.h"
+#include "src/__support/math/ldexpf.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(float, ldexpf, (float x, int exp)) {
-  return fputil::ldexp(x, exp);
+  return math::ldexpf(x, exp);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 2484a2f1e2bd7..ab9d16cc29168 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -2096,6 +2096,14 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_ldexpf",
+    hdrs = ["src/__support/math/ldexpf.h"],
+    deps = [
+        ":__support_fputil_manipulation_functions",
+    ],
+)
+
 ############################### complex targets ################################
 
 libc_function(
@@ -3229,7 +3237,12 @@ libc_math_function(name = "ilogbf16")
 
 libc_math_function(name = "ldexp")
 
-libc_math_function(name = "ldexpf")
+libc_math_function(
+    name = "ldexpf",
+    additional_deps = [
+        ":__support_math_ldexpf",
+    ]
+)
 
 libc_math_function(name = "ldexpl")