[libc][math][c23] Add copysignf16 C23 math function (#94351)

#93566

11 files changed, 94 insertions, 4 deletions

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index bf0610f..6cc1b95 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -501,6 +501,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     # math.h C23 _Float16 entrypoints
     libc.src.math.canonicalizef16
     libc.src.math.ceilf16
+    libc.src.math.copysignf16
     libc.src.math.fabsf16
     libc.src.math.floorf16
     libc.src.math.fromfpf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 0872084..5549236 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -534,6 +534,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     # math.h C23 _Float16 entrypoints
     libc.src.math.canonicalizef16
     libc.src.math.ceilf16
+    libc.src.math.copysignf16
     libc.src.math.fabsf16
     libc.src.math.floorf16
     libc.src.math.fromfpf16
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 9040e24..16fd866 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -112,7 +112,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | canonicalize     | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.11.7              | F.10.8.7                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| copysign         | |check|          | |check|         | |check|                |                      | |check|                | 7.12.11.1              | F.10.8.1                   |
+| copysign         | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.11.1              | F.10.8.1                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | dadd             | N/A              | N/A             |                        | N/A                  |                        | 7.12.14.1              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index df44ed7..dc4e5b8 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -385,6 +385,7 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"copysign", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
           FunctionSpec<"copysignf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,
           FunctionSpec<"copysignl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
+          GuardedFunctionSpec<"copysignf16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>, ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"copysignf128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>, ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT128">,
 
           FunctionSpec<"ceil", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 56174cb..10e997a 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -74,6 +74,7 @@ add_math_entrypoint_object(ceilf128)
 add_math_entrypoint_object(copysign)
 add_math_entrypoint_object(copysignf)
 add_math_entrypoint_object(copysignl)
+add_math_entrypoint_object(copysignf16)
 add_math_entrypoint_object(copysignf128)
 
 add_math_entrypoint_object(cos)
diff --git a/libc/src/math/copysignf16.h b/libc/src/math/copysignf16.h
new file mode 100644
index 0000000..3ddde9f
--- /dev/null
+++ b/libc/src/math/copysignf16.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for copysignf16 -------------------*- 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_MATH_COPYSIGNF16_H
+#define LLVM_LIBC_SRC_MATH_COPYSIGNF16_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float16 copysignf16(float16 x, float16 y);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_COPYSIGNF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 897ce07..1c356d6 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -1240,6 +1240,19 @@ add_entrypoint_object(
 )
 
 add_entrypoint_object(
+  copysignf16
+  SRCS
+    copysignf16.cpp
+  HDRS
+    ../copysignf16.h
+  DEPENDS
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
+add_entrypoint_object(
   copysignf128
   SRCS
     copysignf128.cpp
diff --git a/libc/src/math/generic/copysignf16.cpp b/libc/src/math/generic/copysignf16.cpp
new file mode 100644
index 0000000..435c7e4
--- /dev/null
+++ b/libc/src/math/generic/copysignf16.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of copysignf16 function ----------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/copysignf16.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float16, copysignf16, (float16 x, float16 y)) {
+  return fputil::copysign(x, y);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index b6a3f0b..6b70d89 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -995,6 +995,7 @@ add_fp_unittest(
     CopySignTest.h
   DEPENDS
     libc.src.math.copysign
+    libc.src.__support.CPP.algorithm
     libc.src.__support.FPUtil.fp_bits
 )
 
@@ -1008,6 +1009,7 @@ add_fp_unittest(
     CopySignTest.h
   DEPENDS
     libc.src.math.copysignf
+    libc.src.__support.CPP.algorithm
     libc.src.__support.FPUtil.fp_bits
 )
 
@@ -1021,6 +1023,21 @@ add_fp_unittest(
     CopySignTest.h
   DEPENDS
     libc.src.math.copysignl
+    libc.src.__support.CPP.algorithm
+    libc.src.__support.FPUtil.fp_bits
+)
+
+add_fp_unittest(
+  copysignf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    copysignf16_test.cpp
+  HDRS
+    CopySignTest.h
+  DEPENDS
+    libc.src.math.copysignf16
+    libc.src.__support.CPP.algorithm
     libc.src.__support.FPUtil.fp_bits
 )
 
@@ -1034,6 +1051,7 @@ add_fp_unittest(
     CopySignTest.h
   DEPENDS
     libc.src.math.copysignf128
+    libc.src.__support.CPP.algorithm
     libc.src.__support.FPUtil.fp_bits
 )
 
diff --git a/libc/test/src/math/smoke/CopySignTest.h b/libc/test/src/math/smoke/CopySignTest.h
index 1810560..1eb323a 100644
--- a/libc/test/src/math/smoke/CopySignTest.h
+++ b/libc/test/src/math/smoke/CopySignTest.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_LIBC_TEST_SRC_MATH_SMOKE_COPYSIGNTEST_H
 #define LLVM_LIBC_TEST_SRC_MATH_SMOKE_COPYSIGNTEST_H
 
+#include "src/__support/CPP/algorithm.h"
 #include "test/UnitTest/FEnvSafeTest.h"
 #include "test/UnitTest/FPMatcher.h"
 #include "test/UnitTest/Test.h"
@@ -35,9 +36,11 @@ public:
   }
 
   void testRange(CopySignFunc func) {
-    constexpr StorageType COUNT = 100'000;
-    constexpr StorageType STEP = STORAGE_MAX / COUNT;
-    for (StorageType i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+    constexpr int COUNT = 100'000;
+    constexpr StorageType STEP = LIBC_NAMESPACE::cpp::max(
+        static_cast<StorageType>(STORAGE_MAX / COUNT), StorageType(1));
+    StorageType v = 0;
+    for (int i = 0; i <= COUNT; ++i, v += STEP) {
       FPBits x_bits = FPBits(v);
       T x = T(v);
       if (x_bits.is_nan() || x_bits.is_inf())
diff --git a/libc/test/src/math/smoke/copysignf16_test.cpp b/libc/test/src/math/smoke/copysignf16_test.cpp
new file mode 100644
index 0000000..80a67f1
--- /dev/null
+++ b/libc/test/src/math/smoke/copysignf16_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for copysignf16 -----------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "CopySignTest.h"
+
+#include "src/math/copysignf16.h"
+
+LIST_COPYSIGN_TESTS(float16, LIBC_NAMESPACE::copysignf16)