[libc-commits] [libc] [libc][math][c++23] Add bf16{add, sub}{, f, l, f128} math functions (PR #152774)

via libc-commits libc-commits at lists.llvm.org
Fri Aug 8 11:21:52 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Krishna Pandey (krishna2803)

<details>
<summary>Changes</summary>

This PR adds implements following basic math functions for BFloat16 type along with the tests:
- bf16add
- bf16addf
- bf16addl
- bf16addf128
- bf16sub
- bf16subf
- bf16subl
- bf16subf128

---

Patch is 39.71 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/152774.diff


39 Files Affected:

- (modified) libc/config/linux/x86_64/entrypoints.txt (+14) 
- (modified) libc/src/math/CMakeLists.txt (+10) 
- (added) libc/src/math/bf16add.h (+21) 
- (added) libc/src/math/bf16addf.h (+21) 
- (added) libc/src/math/bf16addf128.h (+21) 
- (added) libc/src/math/bf16addl.h (+21) 
- (added) libc/src/math/bf16sub.h (+21) 
- (added) libc/src/math/bf16subf.h (+21) 
- (added) libc/src/math/bf16subf128.h (+21) 
- (added) libc/src/math/bf16subl.h (+21) 
- (modified) libc/src/math/generic/CMakeLists.txt (+113) 
- (added) libc/src/math/generic/bf16add.cpp (+22) 
- (added) libc/src/math/generic/bf16addf.cpp (+22) 
- (added) libc/src/math/generic/bf16addf128.cpp (+22) 
- (added) libc/src/math/generic/bf16addl.cpp (+22) 
- (added) libc/src/math/generic/bf16sub.cpp (+22) 
- (added) libc/src/math/generic/bf16subf.cpp (+22) 
- (added) libc/src/math/generic/bf16subf128.cpp (+22) 
- (added) libc/src/math/generic/bf16subl.cpp (+22) 
- (modified) libc/test/UnitTest/FPMatcher.h (+1-1) 
- (modified) libc/test/src/math/CMakeLists.txt (+112) 
- (added) libc/test/src/math/bf16add_test.cpp (+14) 
- (added) libc/test/src/math/bf16addf128_test.cpp (+14) 
- (added) libc/test/src/math/bf16addf_test.cpp (+14) 
- (added) libc/test/src/math/bf16addl_test.cpp (+14) 
- (added) libc/test/src/math/bf16sub_test.cpp (+14) 
- (added) libc/test/src/math/bf16subf128_test.cpp (+14) 
- (added) libc/test/src/math/bf16subf_test.cpp (+14) 
- (added) libc/test/src/math/bf16subl_test.cpp (+14) 
- (modified) libc/test/src/math/smoke/CMakeLists.txt (+128) 
- (added) libc/test/src/math/smoke/bf16add_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16addf128_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16addf_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16addl_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16sub_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16subf128_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16subf_test.cpp (+14) 
- (added) libc/test/src/math/smoke/bf16subl_test.cpp (+14) 
- (modified) libc/utils/MPFRWrapper/MPFRUtils.cpp (+33) 


``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 066dc21497691..0a2b24b420ac2 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -896,6 +896,12 @@ endif()
 list(APPEND TARGET_LIBM_ENTRYPOINTS
   # bfloat16 entrypoints
   libc.src.math.ceilbf16
+  libc.src.math.bf16add
+  libc.src.math.bf16addf
+  libc.src.math.bf16addl
+  libc.src.math.bf16sub
+  libc.src.math.bf16subf
+  libc.src.math.bf16subl
   libc.src.math.fabsbf16
   libc.src.math.floorbf16
   libc.src.math.roundbf16
@@ -903,6 +909,14 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.truncbf16
 )
 
+if(LIBC_TYPES_HAS_FLOAT128)
+  list(APPEND TARGET_LIBM_ENTRYPOINTS
+    # math.h C++23 mixed bfloat16 and _Float128 entrypoints
+    libc.src.math.bf16addf128
+    libc.src.math.bf16subf128
+  )
+endif()
+
 if(LIBC_COMPILER_HAS_FIXED_POINT)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # stdfix.h _Fract and _Accum entrypoints
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index c3840d3c4aa89..660c3681717c8 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -563,3 +563,13 @@ add_math_entrypoint_object(ufromfpxf)
 add_math_entrypoint_object(ufromfpxl)
 add_math_entrypoint_object(ufromfpxf16)
 add_math_entrypoint_object(ufromfpxf128)
+
+add_math_entrypoint_object(bf16add)
+add_math_entrypoint_object(bf16addf)
+add_math_entrypoint_object(bf16addl)
+add_math_entrypoint_object(bf16addf128)
+
+add_math_entrypoint_object(bf16sub)
+add_math_entrypoint_object(bf16subf)
+add_math_entrypoint_object(bf16subl)
+add_math_entrypoint_object(bf16subf128)
diff --git a/libc/src/math/bf16add.h b/libc/src/math/bf16add.h
new file mode 100644
index 0000000000000..a29970eb334fa
--- /dev/null
+++ b/libc/src/math/bf16add.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16add -----------------------*- 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_BF16ADD_H
+#define LLVM_LIBC_SRC_MATH_BF16ADD_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16add(double x, double y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16ADD_H
diff --git a/libc/src/math/bf16addf.h b/libc/src/math/bf16addf.h
new file mode 100644
index 0000000000000..80a5e2a7640df
--- /dev/null
+++ b/libc/src/math/bf16addf.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16addf ----------------------*- 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_BF16ADDF_H
+#define LLVM_LIBC_SRC_MATH_BF16ADDF_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16addf(float x, float y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16ADDF_H
diff --git a/libc/src/math/bf16addf128.h b/libc/src/math/bf16addf128.h
new file mode 100644
index 0000000000000..3c2f3a15eb39c
--- /dev/null
+++ b/libc/src/math/bf16addf128.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16addf128 -------------------*- 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_BF16ADDF128_H
+#define LLVM_LIBC_SRC_MATH_BF16ADDF128_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16addf128(float128 x, float128 y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16ADDF128_H
diff --git a/libc/src/math/bf16addl.h b/libc/src/math/bf16addl.h
new file mode 100644
index 0000000000000..a9e7d68660728
--- /dev/null
+++ b/libc/src/math/bf16addl.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16addl ----------------------*- 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_BF16ADDL_H
+#define LLVM_LIBC_SRC_MATH_BF16ADDL_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16addl(long double x, long double y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16ADDL_H
diff --git a/libc/src/math/bf16sub.h b/libc/src/math/bf16sub.h
new file mode 100644
index 0000000000000..8108e9146859f
--- /dev/null
+++ b/libc/src/math/bf16sub.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16sub -----------------------*- 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_BF16SUB_H
+#define LLVM_LIBC_SRC_MATH_BF16SUB_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16sub(double x, double y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16SUB_H
diff --git a/libc/src/math/bf16subf.h b/libc/src/math/bf16subf.h
new file mode 100644
index 0000000000000..1bd79bfe119ce
--- /dev/null
+++ b/libc/src/math/bf16subf.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16subf ----------------------*- 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_BF16SUBF_H
+#define LLVM_LIBC_SRC_MATH_BF16SUBF_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16subf(float x, float y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16SUBF_H
diff --git a/libc/src/math/bf16subf128.h b/libc/src/math/bf16subf128.h
new file mode 100644
index 0000000000000..19590e8c67508
--- /dev/null
+++ b/libc/src/math/bf16subf128.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16subf128 -------------------*- 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_BF16SUBF128_H
+#define LLVM_LIBC_SRC_MATH_BF16SUBF128_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16subf128(float128 x, float128 y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16SUBF128_H
diff --git a/libc/src/math/bf16subl.h b/libc/src/math/bf16subl.h
new file mode 100644
index 0000000000000..13b2093a92ffa
--- /dev/null
+++ b/libc/src/math/bf16subl.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for bf16subl ----------------------*- 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_BF16SUBL_H
+#define LLVM_LIBC_SRC_MATH_BF16SUBL_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 bf16subl(long double x, long double y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_BF16SUBL_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 893606609dfc3..5aeacc85d4d5e 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4911,3 +4911,116 @@ add_header_library(
     libc.src.__support.math.expf16_utils
     libc.src.__support.math.exp10_float16_constants
 )
+
+add_entrypoint_object(
+  bf16add
+  SRCS
+    bf16add.cpp
+  HDRS
+    ../bf16add.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16addf
+  SRCS
+    bf16addf.cpp
+  HDRS
+    ../bf16addf.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16addl
+  SRCS
+    bf16addl.cpp
+  HDRS
+    ../bf16addl.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16addf128
+  SRCS
+    bf16addf128.cpp
+  HDRS
+    ../bf16addf128.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+
+add_entrypoint_object(
+  bf16sub
+  SRCS
+    bf16sub.cpp
+  HDRS
+    ../bf16sub.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16subf
+  SRCS
+    bf16subf.cpp
+  HDRS
+    ../bf16subf.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16subl
+  SRCS
+    bf16subl.cpp
+  HDRS
+    ../bf16subl.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
+
+add_entrypoint_object(
+  bf16subf128
+  SRCS
+    bf16subf128.cpp
+  HDRS
+    ../bf16subf128.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.generic.add_sub
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
diff --git a/libc/src/math/generic/bf16add.cpp b/libc/src/math/generic/bf16add.cpp
new file mode 100644
index 0000000000000..686848576f7a5
--- /dev/null
+++ b/libc/src/math/generic/bf16add.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16add 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/bf16add.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16add, (double x, double y)) {
+  return fputil::generic::add<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16addf.cpp b/libc/src/math/generic/bf16addf.cpp
new file mode 100644
index 0000000000000..cd57a5ffad53d
--- /dev/null
+++ b/libc/src/math/generic/bf16addf.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16addf 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/bf16addf.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16addf, (float x, float y)) {
+  return fputil::generic::add<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16addf128.cpp b/libc/src/math/generic/bf16addf128.cpp
new file mode 100644
index 0000000000000..ff94d3aff1581
--- /dev/null
+++ b/libc/src/math/generic/bf16addf128.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16addf128 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/bf16addf128.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16addf128, (float128 x, float128 y)) {
+  return fputil::generic::add<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16addl.cpp b/libc/src/math/generic/bf16addl.cpp
new file mode 100644
index 0000000000000..7f053c1870d9b
--- /dev/null
+++ b/libc/src/math/generic/bf16addl.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16addl 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/bf16addl.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16addl, (long double x, long double y)) {
+  return fputil::generic::add<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16sub.cpp b/libc/src/math/generic/bf16sub.cpp
new file mode 100644
index 0000000000000..5148f3657abaf
--- /dev/null
+++ b/libc/src/math/generic/bf16sub.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16sub 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/bf16sub.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16sub, (double x, double y)) {
+  return fputil::generic::sub<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16subf.cpp b/libc/src/math/generic/bf16subf.cpp
new file mode 100644
index 0000000000000..dc303329b1dbd
--- /dev/null
+++ b/libc/src/math/generic/bf16subf.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16subf 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/bf16subf.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16subf, (float x, float y)) {
+  return fputil::generic::sub<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16subf128.cpp b/libc/src/math/generic/bf16subf128.cpp
new file mode 100644
index 0000000000000..931c952386597
--- /dev/null
+++ b/libc/src/math/generic/bf16subf128.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16subf128 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/bf16subf128.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16subf128, (float128 x, float128 y)) {
+  return fputil::generic::sub<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/bf16subl.cpp b/libc/src/math/generic/bf16subl.cpp
new file mode 100644
index 0000000000000..315675640194f
--- /dev/null
+++ b/libc/src/math/generic/bf16subl.cpp
@@ -0,0 +1,22 @@
+//===-- Implementation of bf16subl 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/bf16subl.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/generic/add_sub.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, bf16subl, (long double x, long double y)) {
+  return fputil::generic::sub<bfloat16>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/UnitTest/FPMatcher.h b/libc/test/UnitTest/FPMatcher.h
index 592cd1b3f37ab..e8d920cb11f54 100644
--- a/libc/test/UnitTest/FPMatcher.h
+++ b/libc/test/UnitTest/FPMatcher.h
@@ -271,7 +271,7 @@ struct ModifyMXCSR {
       expected)                                                                \
       .match(actual)
 
-#define EXPECT_FP_IS_NAN(actual) EXPECT_TRUE((actual) != (actual))
+#define EXPECT_FP_IS_NAN(actual) EXPECT_TRUE(FPBits(actual).is_nan())
 
 #define ASSERT_FP_EQ(expected, actual)                                         \
   ASSERT_THAT(actual, LIBC_NAMESPACE::testing::getMatcher<                     \
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 43cde0d68873e..a74f9fe471963 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/152774


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