[libc-commits] [libc] [llvm] [libc][math][c23] Add cosbf16 math function (PR #185801)
via libc-commits
libc-commits at lists.llvm.org
Thu Jun 25 16:48:53 PDT 2026
https://github.com/Sukumarsawant updated https://github.com/llvm/llvm-project/pull/185801
>From cb270eda358268092891c8da5b4533f36aff5224 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Tue, 10 Mar 2026 19:30:18 +0530
Subject: [PATCH 1/5] feat: added entrypoints
---
libc/config/baremetal/aarch64/entrypoints.txt | 1 +
libc/config/baremetal/arm/entrypoints.txt | 1 +
libc/config/baremetal/riscv/entrypoints.txt | 1 +
libc/config/darwin/aarch64/entrypoints.txt | 1 +
libc/config/darwin/x86_64/entrypoints.txt | 1 +
libc/config/gpu/amdgpu/entrypoints.txt | 1 +
libc/config/gpu/nvptx/entrypoints.txt | 1 +
libc/config/linux/aarch64/entrypoints.txt | 1 +
libc/config/linux/arm/entrypoints.txt | 1 +
libc/config/linux/riscv/entrypoints.txt | 1 +
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/config/windows/entrypoints.txt | 1 +
12 files changed, 12 insertions(+)
diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
index 73f4c1f937388..51ae6c3652471 100644
--- a/libc/config/baremetal/aarch64/entrypoints.txt
+++ b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -818,6 +818,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.canonicalizebf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
+ libc.src.math.cosbf16
libc.src.math.fabsbf16
libc.src.math.fdimbf16
libc.src.math.floorbf16
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index a5c1b20a7a434..7bb3f1e24690d 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -827,6 +827,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index 60bc924993fc8..a186fa4ddb5b1 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -824,6 +824,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/darwin/aarch64/entrypoints.txt b/libc/config/darwin/aarch64/entrypoints.txt
index 6f4916b203de5..3f596e88aabef 100644
--- a/libc/config/darwin/aarch64/entrypoints.txt
+++ b/libc/config/darwin/aarch64/entrypoints.txt
@@ -637,6 +637,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/darwin/x86_64/entrypoints.txt b/libc/config/darwin/x86_64/entrypoints.txt
index c09ccadbb8c4c..d08f024467d5d 100644
--- a/libc/config/darwin/x86_64/entrypoints.txt
+++ b/libc/config/darwin/x86_64/entrypoints.txt
@@ -254,6 +254,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/gpu/amdgpu/entrypoints.txt b/libc/config/gpu/amdgpu/entrypoints.txt
index 60a98cf5c773f..7a7b4a4ccbe62 100644
--- a/libc/config/gpu/amdgpu/entrypoints.txt
+++ b/libc/config/gpu/amdgpu/entrypoints.txt
@@ -662,6 +662,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/gpu/nvptx/entrypoints.txt b/libc/config/gpu/nvptx/entrypoints.txt
index 70bdbde97e868..1c6a5bb19214b 100644
--- a/libc/config/gpu/nvptx/entrypoints.txt
+++ b/libc/config/gpu/nvptx/entrypoints.txt
@@ -664,6 +664,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 570f7666ba67b..d10a95c223162 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -937,6 +937,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index e6aa6091ed550..188845cb6c140 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -508,6 +508,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 2508de5cfe5a4..7ad35415c9259 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -958,6 +958,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 5ace968a739c8..48119762feb4c 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1029,6 +1029,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index 3c68290675b11..bb3182d40740f 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -344,6 +344,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.bf16subf
libc.src.math.bf16subl
libc.src.math.canonicalizebf16
+ libc.src.math.cosbf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
libc.src.math.fabsbf16
>From c25cea4738beeadf468b707112b12d07080c92d5 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Tue, 10 Mar 2026 23:09:24 +0530
Subject: [PATCH 2/5] feat: final Implementation for cosbf16
temp
feat: Implementation for cosbf16
nit
---
libc/shared/math.h | 1 +
libc/shared/math/cosbf16.h | 23 ++++++
libc/src/__support/math/CMakeLists.txt | 16 ++++
libc/src/__support/math/cosbf16.h | 76 +++++++++++++++++++
libc/src/math/CMakeLists.txt | 1 +
libc/src/math/cosbf16.h | 21 +++++
libc/src/math/generic/CMakeLists.txt | 10 +++
libc/src/math/generic/cosbf16.cpp | 17 +++++
libc/test/shared/CMakeLists.txt | 1 +
libc/test/shared/shared_math_test.cpp | 5 ++
libc/test/src/math/CMakeLists.txt | 13 ++++
libc/test/src/math/cosbf16_test.cpp | 45 +++++++++++
libc/test/src/math/smoke/CMakeLists.txt | 13 ++++
libc/test/src/math/smoke/cosbf16_test.cpp | 40 ++++++++++
.../llvm-project-overlay/libc/BUILD.bazel | 23 ++++++
15 files changed, 305 insertions(+)
create mode 100644 libc/shared/math/cosbf16.h
create mode 100644 libc/src/__support/math/cosbf16.h
create mode 100644 libc/src/math/cosbf16.h
create mode 100644 libc/src/math/generic/cosbf16.cpp
create mode 100644 libc/test/src/math/cosbf16_test.cpp
create mode 100644 libc/test/src/math/smoke/cosbf16_test.cpp
diff --git a/libc/shared/math.h b/libc/shared/math.h
index 2e8a574e4d042..a17a84ed2c341 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -82,6 +82,7 @@
#include "math/copysignf16.h"
#include "math/copysignl.h"
#include "math/cos.h"
+#include "math/cosbf16.h"
#include "math/cosf.h"
#include "math/cosf16.h"
#include "math/coshf.h"
diff --git a/libc/shared/math/cosbf16.h b/libc/shared/math/cosbf16.h
new file mode 100644
index 0000000000000..5ff8ce8dea8dd
--- /dev/null
+++ b/libc/shared/math/cosbf16.h
@@ -0,0 +1,23 @@
+//===-- Shared cosbf16 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_COSBF16_H
+#define LLVM_LIBC_SHARED_MATH_COSBF16_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/cosbf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::cosbf16;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_COSBF16_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index a57086a31dc03..01c5b91cf2e54 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -2829,6 +2829,22 @@ add_header_library(
libc.src.__support.macros.optimization
)
+add_header_library(
+ cosbf16
+ HDRS
+ cosbf16.h
+ DEPENDS
+ .sincosf_utils
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.macros.optimization
+ libc.src.__support.FPUtil.bfloat16
+)
+
add_header_library(
cosf16
HDRS
diff --git a/libc/src/__support/math/cosbf16.h b/libc/src/__support/math/cosbf16.h
new file mode 100644
index 0000000000000..7f7eead2d760b
--- /dev/null
+++ b/libc/src/__support/math/cosbf16.h
@@ -0,0 +1,76 @@
+//===-- Implementation header for cosbf16 -----------------------*- 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_COSBF16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_COSBF16_H
+
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "sincosf_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE bfloat16 cosbf16(bfloat16 x) {
+ using namespace sincosf_utils_internal;
+
+ using FPBits = fputil::FPBits<bfloat16>;
+ FPBits xbits(x);
+
+ uint16_t x_u = xbits.uintval();
+ uint16_t x_abs = x_u & 0x7fff;
+ float xf = x;
+
+ if (x_abs < 0x7f80) {
+
+ // cos(+/-0) = 1
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return fputil::cast<bfloat16>(1.0f);
+
+ double xd = static_cast<double>(xf);
+ uint32_t x_abs_d = fputil::FPBits<float>(xf).uintval() & 0x7fffffff;
+ double sin_k, cos_k, sin_y, cosm1_y;
+
+ sincosf_eval(xd, x_abs_d, sin_k, cos_k, sin_y, cosm1_y);
+ // using cos(a + b) = cos(a)*cos(b) - sin(a)*sin(b)
+ // cos(x) = cos_k*cos_y - sin_k*sin_y
+ // but cosm1_y = cos_y - 1 --> cos_y = cosm1_y + 1
+ // cos(x) = cos_k*cosm1_y + cos_k - sin_k * sin_y
+
+ return fputil::cast<bfloat16>(fputil::multiply_add(
+ cosm1_y, cos_k, fputil::multiply_add(-sin_y, sin_k, cos_k)));
+ }
+
+ // nan
+ if (xbits.is_nan()) {
+ if (xbits.is_signaling_nan()) {
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ return x;
+ }
+
+ // +/- inf
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+
+ return x + FPBits::quiet_nan().get_val();
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_COSBF16_H
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 4823ceefd7475..0e5a4cb50f8ad 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -116,6 +116,7 @@ add_math_entrypoint_object(copysignf128)
add_math_entrypoint_object(copysignbf16)
add_math_entrypoint_object(cos)
+add_math_entrypoint_object(cosbf16)
add_math_entrypoint_object(cosf)
add_math_entrypoint_object(cosf16)
diff --git a/libc/src/math/cosbf16.h b/libc/src/math/cosbf16.h
new file mode 100644
index 0000000000000..75306265cb35d
--- /dev/null
+++ b/libc/src/math/cosbf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for cosbf16 -----------------------*- 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_COSBF16_H
+#define LLVM_LIBC_SRC_MATH_COSBF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 cosbf16(bfloat16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_COSBF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 5a5bd84213a55..0a9166aa8e7be 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -297,6 +297,16 @@ add_entrypoint_object(
libc.src.__support.math.cosf
)
+add_entrypoint_object(
+ cosbf16
+ SRCS
+ cosbf16.cpp
+ HDRS
+ ../cosbf16.h
+ DEPENDS
+ libc.src.__support.math.cosbf16
+)
+
add_entrypoint_object(
cosf16
SRCS
diff --git a/libc/src/math/generic/cosbf16.cpp b/libc/src/math/generic/cosbf16.cpp
new file mode 100644
index 0000000000000..95cb90f37c3f9
--- /dev/null
+++ b/libc/src/math/generic/cosbf16.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation for cosbf16 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/cosbf16.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/math/cosbf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, cosbf16, (bfloat16 x)) { return math::cosbf16(x); }
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 9b990dd5a5c84..f950e7666213e 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -89,6 +89,7 @@ add_fp_unittest(
libc.src.__support.math.copysignf16
libc.src.__support.math.copysignl
libc.src.__support.math.cos
+ libc.src.__support.math.cosbf16
libc.src.__support.math.cosf
libc.src.__support.math.cosf16
libc.src.__support.math.coshf
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index 5877729ae7931..2260c75f142c3 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -768,6 +768,11 @@ TEST(LlvmLibcSharedMathTest, AllBFloat16) {
&canonicalizebf16_x));
EXPECT_FP_EQ(bfloat16(0.0), canonicalizebf16_cx);
EXPECT_FP_EQ(bfloat16(0.0), LIBC_NAMESPACE::shared::cbrtbf16(bfloat16(0.0)));
+ EXPECT_FP_EQ(bfloat16(1.0), LIBC_NAMESPACE::shared::cosbf16(bfloat16(0.0)));
+ EXPECT_FP_EQ(bfloat16(5.0), LIBC_NAMESPACE::shared::bf16addf(2.0f, 3.0f));
+ EXPECT_FP_EQ(bfloat16(5.0), LIBC_NAMESPACE::shared::bf16addl(2L, 3L));
+ EXPECT_FP_EQ(bfloat16(10.0),
+ LIBC_NAMESPACE::shared::bf16fmaf(2.0f, 3.0f, 4.0f));
EXPECT_FP_EQ(bfloat16(0.0), LIBC_NAMESPACE::shared::ceilbf16(bfloat16(0.0)));
EXPECT_FP_EQ(bfloat16(0.0), LIBC_NAMESPACE::shared::copysignbf16(
bfloat16(0.0), bfloat16(0.0)));
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 31f6468e01110..9b9105438fbd1 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -42,6 +42,19 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ cosbf16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ cosbf16_test.cpp
+ DEPENDS
+ libc.src.math.cosbf16
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.bfloat16
+)
+
add_fp_unittest(
cosf16_test
NEED_MPFR
diff --git a/libc/test/src/math/cosbf16_test.cpp b/libc/test/src/math/cosbf16_test.cpp
new file mode 100644
index 0000000000000..dadae218f38c6
--- /dev/null
+++ b/libc/test/src/math/cosbf16_test.cpp
@@ -0,0 +1,45 @@
+//===-- Exhaustive test for cosbf16 ---------------------------------------===//
+//
+// 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/__support/FPUtil/bfloat16.h"
+#include "src/math/cosbf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcCosBf16Test = LIBC_NAMESPACE::testing::FPTest<bfloat16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf]
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7f80U;
+
+// Range: [-Inf, 0]
+static constexpr uint16_t NEG_START = 0x8000U;
+static constexpr uint16_t NEG_STOP = 0xff80U;
+
+TEST_F(LlvmLibcCosBf16Test, PositiveRange) {
+
+ for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+ bfloat16 x = FPBits(v).get_val();
+
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cos, x,
+ LIBC_NAMESPACE::cosbf16(x), 0.5);
+ }
+}
+
+TEST_F(LlvmLibcCosBf16Test, NegativeRange) {
+
+ for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+ bfloat16 x = FPBits(v).get_val();
+
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cos, x,
+ LIBC_NAMESPACE::cosbf16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 73d2265322c4d..744541a8c7a0a 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -12,6 +12,19 @@ add_fp_unittest(
libc.src.math.cosf
)
+add_fp_unittest(
+ cosbf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ cosbf16_test.cpp
+ DEPENDS
+ libc.hdr.errno_macros
+ libc.src.math.cosbf16
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.bfloat16
+)
+
add_fp_unittest(
cosf16_test
SUITE
diff --git a/libc/test/src/math/smoke/cosbf16_test.cpp b/libc/test/src/math/smoke/cosbf16_test.cpp
new file mode 100644
index 0000000000000..ae69fddd569a7
--- /dev/null
+++ b/libc/test/src/math/smoke/cosbf16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Unittests for cosbf16 ---------------------------------------------===//
+//
+// 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 "hdr/errno_macros.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/math/cosbf16.h"
+#include "test/UnitTest/FEnvSafeTest.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+class LlvmLibcCosBf16Test : public LIBC_NAMESPACE::testing::FEnvSafeTest {
+ DECLARE_SPECIAL_CONSTANTS(bfloat16)
+public:
+ void test_special_numbers() {
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::cosbf16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+ aNaN, LIBC_NAMESPACE::cosbf16(sNaN), FE_INVALID);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(1.0), LIBC_NAMESPACE::cosbf16(zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(1.0), LIBC_NAMESPACE::cosbf16(neg_zero));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::cosbf16(inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::cosbf16(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+ }
+};
+TEST_F(LlvmLibcCosBf16Test, SpecialNumbers) { test_special_numbers(); }
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 68bb1f1d60bf2..857e00922e60e 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -6650,6 +6650,22 @@ libc_support_library(
],
)
+libc_support_library(
+ name = "__support_math_cosbf16",
+ hdrs = ["src/__support/math/cosbf16.h"],
+ deps = [
+ ":__support_fputil_bfloat16",
+ ":__support_fputil_cast",
+ ":__support_fputil_fenv_impl",
+ ":__support_fputil_fp_bits",
+ ":__support_fputil_multiply_add",
+ ":__support_macros_optimization",
+ ":__support_sincosf_utils",
+ ":hdr_errno_macros",
+ ":hdr_fenv_macros",
+ ],
+)
+
libc_support_library(
name = "__support_math_cosf16",
hdrs = ["src/__support/math/cosf16.h"],
@@ -10464,6 +10480,13 @@ libc_math_function(
additional_deps = [":__support_math_cosf"],
)
+libc_math_function(
+ name = "cosbf16",
+ additional_deps = [
+ ":__support_math_cosbf16",
+ ],
+)
+
libc_math_function(
name = "cosf16",
additional_deps = [
>From 0d5d5c5f092c091bee4bd989789b7a14b3226157 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Wed, 11 Mar 2026 10:19:56 +0530
Subject: [PATCH 3/5] checked index.rst
---
libc/docs/headers/math/index.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
index 8f8f381054002..e1c1a1a5f8f09 100644
--- a/libc/docs/headers/math/index.rst
+++ b/libc/docs/headers/math/index.rst
@@ -283,7 +283,7 @@ Higher Math Functions
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
| compoundn | | | | | | | 7.12.7.2 | F.10.4.2 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
-| cos | |check| | |check| | | |check| | | | 7.12.4.5 | F.10.1.5 |
+| cos | |check| | |check| | | |check| | | |check| | 7.12.4.5 | F.10.1.5 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
| cosh | |check| | | | |check| | | | 7.12.5.4 | F.10.2.4 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
>From 4e40bd40388756c4377ebd8d1771ad183f0468aa Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Fri, 26 Jun 2026 04:35:39 +0530
Subject: [PATCH 4/5] nits
---
libc/src/__support/math/cosbf16.h | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/libc/src/__support/math/cosbf16.h b/libc/src/__support/math/cosbf16.h
index 7f7eead2d760b..ce161f0e5e071 100644
--- a/libc/src/__support/math/cosbf16.h
+++ b/libc/src/__support/math/cosbf16.h
@@ -34,16 +34,15 @@ LIBC_INLINE bfloat16 cosbf16(bfloat16 x) {
float xf = x;
if (x_abs < 0x7f80) {
-
// cos(+/-0) = 1
- if (LIBC_UNLIKELY(x_abs == 0U))
+ if (LIBC_UNLIKELY(x_abs == 0))
return fputil::cast<bfloat16>(1.0f);
double xd = static_cast<double>(xf);
- uint32_t x_abs_d = fputil::FPBits<float>(xf).uintval() & 0x7fffffff;
+ uint32_t x_abs_f = fputil::FPBits<float>(xf).uintval() & 0x7fffffff;
double sin_k, cos_k, sin_y, cosm1_y;
- sincosf_eval(xd, x_abs_d, sin_k, cos_k, sin_y, cosm1_y);
+ sincosf_eval(xd, x_abs_f, sin_k, cos_k, sin_y, cosm1_y);
// using cos(a + b) = cos(a)*cos(b) - sin(a)*sin(b)
// cos(x) = cos_k*cos_y - sin_k*sin_y
// but cosm1_y = cos_y - 1 --> cos_y = cosm1_y + 1
@@ -53,7 +52,7 @@ LIBC_INLINE bfloat16 cosbf16(bfloat16 x) {
cosm1_y, cos_k, fputil::multiply_add(-sin_y, sin_k, cos_k)));
}
- // nan
+ // NaN
if (xbits.is_nan()) {
if (xbits.is_signaling_nan()) {
fputil::raise_except_if_required(FE_INVALID);
>From 4fad66a3df006f731e5603a773ab1fb3ad0a3c17 Mon Sep 17 00:00:00 2001
From: Sukumarsawant <sawantsukumar at gmail.com>
Date: Fri, 26 Jun 2026 05:17:19 +0530
Subject: [PATCH 5/5] add freebsd entrypoint
---
libc/config/freebsd/x86_64/entrypoints.txt | 1 +
1 file changed, 1 insertion(+)
diff --git a/libc/config/freebsd/x86_64/entrypoints.txt b/libc/config/freebsd/x86_64/entrypoints.txt
index 7b8b8384e6dd8..7165b034a2dc6 100644
--- a/libc/config/freebsd/x86_64/entrypoints.txt
+++ b/libc/config/freebsd/x86_64/entrypoints.txt
@@ -580,6 +580,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.canonicalizebf16
libc.src.math.ceilbf16
libc.src.math.copysignbf16
+ libc.src.math.cosbf16
libc.src.math.fabsbf16
libc.src.math.fdimbf16
libc.src.math.floorbf16
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