[libc][math] Refactor ilogb implementation to header-only in src/__support/math folder. (#175504)

closes #175348

libc/shared/math.h

@@ -68,6 +68,7 @@
 #include "math/fsqrt.h"
 #include "math/fsqrtf128.h"
 #include "math/hypotf.h"
+#include "math/ilogb.h"
 #include "math/ilogbf.h"
 #include "math/ilogbf128.h"
 #include "math/ilogbf16.h"

libc/shared/math/ilogb.h

@@ -0,0 +1,23 @@
+//===-- Shared ilogb 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_ILOGB_H
+#define LLVM_LIBC_SHARED_MATH_ILOGB_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/ilogb.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::ilogb;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_ILOGB_H

libc/src/__support/math/CMakeLists.txt

@@ -667,6 +667,16 @@ add_header_library(
     libc.include.llvm-libc-macros.float16_macros
 )
 
+add_header_library(
+  ilogb
+  HDRS
+    ilogb.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.macros.config
+    libc.src.__support.FPUtil.manipulation_functions
+)
+
 add_header_library(
   ilogbf16
   HDRS

libc/src/__support/math/ilogb.h

@@ -0,0 +1,27 @@
+//===-- Implementation header for ilogb -------------------------*- 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_ILOGB_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_ILOGB_H
+
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE static constexpr int ilogb(double x) {
+  return fputil::intlogb<int>(x);
+}
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ILOGB_H

libc/src/math/generic/CMakeLists.txt

@@ -1720,7 +1720,7 @@ add_entrypoint_object(
   HDRS
     ../ilogb.h
   DEPENDS
-    libc.src.__support.FPUtil.manipulation_functions
+    libc.src.__support.math.ilogb
 )
 
 add_entrypoint_object(

libc/src/math/generic/ilogb.cpp

@@ -7,12 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/ilogb.h"
-#include "src/__support/FPUtil/ManipulationFunctions.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/config.h"
+#include "src/__support/math/ilogb.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-LLVM_LIBC_FUNCTION(int, ilogb, (double x)) { return fputil::intlogb<int>(x); }
+LLVM_LIBC_FUNCTION(int, ilogb, (double x)) { return math::ilogb(x); }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/test/shared/CMakeLists.txt

@@ -64,6 +64,7 @@ add_fp_unittest(
     libc.src.__support.math.fsqrt
     libc.src.__support.math.fsqrtf128
     libc.src.__support.math.hypotf
+    libc.src.__support.math.ilogb
     libc.src.__support.math.ilogbf
     libc.src.__support.math.ilogbf16
     libc.src.__support.math.ilogbf128

libc/test/shared/shared_math_test.cpp

@@ -119,8 +119,9 @@ TEST(LlvmLibcSharedMathTest, AllDouble) {
   EXPECT_FP_EQ(0x0p+0, LIBC_NAMESPACE::shared::log1p(0.0));
   EXPECT_FP_EQ(0x0p+0, LIBC_NAMESPACE::shared::log2(1.0));
   EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::shared::sin(0.0));
-  EXPECT_EQ(0L, LIBC_NAMESPACE::shared::llogb(1.0));
   EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::shared::tan(0.0));
+  EXPECT_EQ(0, LIBC_NAMESPACE::shared::ilogb(1.0));
+  EXPECT_EQ(0L, LIBC_NAMESPACE::shared::llogb(1.0));
 }
 
 TEST(LlvmLibcSharedMathTest, AllLongDouble) {

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

@@ -2974,6 +2974,16 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_ilogb",
+    hdrs = ["src/__support/math/ilogb.h"],
+    deps = [
+        ":__support_common",
+        ":__support_fputil_manipulation_functions",
+        ":__support_macros_config",
+    ],
+)
+
 libc_support_library(
     name = "__support_math_ilogbf16",
     hdrs = ["src/__support/math/ilogbf16.h"],
@@ -4745,7 +4755,12 @@ libc_math_function(
     ],
 )
 
-libc_math_function(name = "ilogb")
+libc_math_function(
+    name = "ilogb",
+    additional_deps = [
+        ":__support_math_ilogb",
+    ],
+)
 
 libc_math_function(
     name = "ilogbf",