[libc-commits] [libc] 699f154 - [libc][math][c++23] Add nanbf16 math function (#153995)
via libc-commits
libc-commits at lists.llvm.org
Sat Aug 23 02:15:56 PDT 2025
Author: Krishna Pandey
Date: 2025-08-23T14:45:53+05:30
New Revision: 699f15426faeb673b12d7bd567669194d04a0034
URL: https://github.com/llvm/llvm-project/commit/699f15426faeb673b12d7bd567669194d04a0034
DIFF: https://github.com/llvm/llvm-project/commit/699f15426faeb673b12d7bd567669194d04a0034.diff
LOG: [libc][math][c++23] Add nanbf16 math function (#153995)
This PR adds the nanbf16 basic math function for BFloat16 type along
with the tests.
---------
Signed-off-by: Krishna Pandey <kpandey81930 at gmail.com>
Added:
libc/src/math/generic/nanbf16.cpp
libc/src/math/nanbf16.h
libc/test/src/math/smoke/nanbf16_test.cpp
Modified:
libc/config/baremetal/aarch64/entrypoints.txt
libc/config/baremetal/arm/entrypoints.txt
libc/config/baremetal/riscv/entrypoints.txt
libc/config/darwin/aarch64/entrypoints.txt
libc/config/darwin/x86_64/entrypoints.txt
libc/config/gpu/amdgpu/entrypoints.txt
libc/config/gpu/nvptx/entrypoints.txt
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/arm/entrypoints.txt
libc/config/linux/riscv/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/config/windows/entrypoints.txt
libc/docs/headers/math/index.rst
libc/src/__support/FPUtil/BasicOperations.h
libc/src/math/CMakeLists.txt
libc/src/math/generic/CMakeLists.txt
libc/test/src/math/smoke/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
index 5f72793beecb4..c4ec03fc146e8 100644
--- a/libc/config/baremetal/aarch64/entrypoints.txt
+++ b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -788,6 +788,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index 244dd2e87b1fd..d9e173a71e47a 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -791,6 +791,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index 32980c4a1d222..9b0cf14037fae 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -791,6 +791,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/darwin/aarch64/entrypoints.txt b/libc/config/darwin/aarch64/entrypoints.txt
index 3684713474cbc..2a634852a2ed0 100644
--- a/libc/config/darwin/aarch64/entrypoints.txt
+++ b/libc/config/darwin/aarch64/entrypoints.txt
@@ -621,6 +621,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/darwin/x86_64/entrypoints.txt b/libc/config/darwin/x86_64/entrypoints.txt
index 7482a80c37d33..6a18d557f86fb 100644
--- a/libc/config/darwin/x86_64/entrypoints.txt
+++ b/libc/config/darwin/x86_64/entrypoints.txt
@@ -264,6 +264,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/gpu/amdgpu/entrypoints.txt b/libc/config/gpu/amdgpu/entrypoints.txt
index a88c74be2997a..008f7c7bd642c 100644
--- a/libc/config/gpu/amdgpu/entrypoints.txt
+++ b/libc/config/gpu/amdgpu/entrypoints.txt
@@ -647,6 +647,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/gpu/nvptx/entrypoints.txt b/libc/config/gpu/nvptx/entrypoints.txt
index d10b820caeeac..7d36aa4eb40f9 100644
--- a/libc/config/gpu/nvptx/entrypoints.txt
+++ b/libc/config/gpu/nvptx/entrypoints.txt
@@ -649,6 +649,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index b1fdee76af934..d04a382de494d 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -876,6 +876,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index 8f21976e9e88e..865392a918624 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -491,6 +491,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 69d7519118198..207608c431a9b 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -894,6 +894,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 786c16dac5b06..2ba2b6874e2e5 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -927,6 +927,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index 541d9fee1adf5..32a6a578aae13 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -337,6 +337,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
libc.src.math.fromfpbf16
libc.src.math.fromfpxbf16
libc.src.math.getpayloadbf16
+ libc.src.math.nanbf16
libc.src.math.nextafterbf16
libc.src.math.nextdownbf16
libc.src.math.nexttowardbf16
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
index 4d6e0cc4c88f1..1481992815857 100644
--- a/libc/docs/headers/math/index.rst
+++ b/libc/docs/headers/math/index.rst
@@ -211,7 +211,7 @@ Basic Operations
+------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
| modf | |check| | |check| | |check| | |check| | |check| | | 7.12.6.18 | F.10.3.18 |
+------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
-| nan | |check| | |check| | |check| | |check| | |check| | | 7.12.11.2 | F.10.8.2 |
+| nan | |check| | |check| | |check| | |check| | |check| | |check| | 7.12.11.2 | F.10.8.2 |
+------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
| nearbyint | |check| | |check| | |check| | |check| | |check| | | 7.12.9.3 | F.10.6.3 |
+------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/src/__support/FPUtil/BasicOperations.h b/libc/src/__support/FPUtil/BasicOperations.h
index 2357b053b60b8..994237ba8492e 100644
--- a/libc/src/__support/FPUtil/BasicOperations.h
+++ b/libc/src/__support/FPUtil/BasicOperations.h
@@ -354,7 +354,10 @@ LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<T>, T> getpayload(T x) {
return static_cast<T>(payload_dfloat);
} else {
- return static_cast<T>(payload);
+ if constexpr (cpp::is_same_v<T, bfloat16>)
+ return T(static_cast<int>(payload));
+ else
+ return static_cast<T>(payload);
}
}
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index d3afce514a000..a90c5ebcee244 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -422,6 +422,7 @@ add_math_entrypoint_object(nanf)
add_math_entrypoint_object(nanl)
add_math_entrypoint_object(nanf16)
add_math_entrypoint_object(nanf128)
+add_math_entrypoint_object(nanbf16)
add_math_entrypoint_object(nearbyint)
add_math_entrypoint_object(nearbyintf)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index fd3442f912172..3f13066c19d3a 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -3432,6 +3432,22 @@ add_entrypoint_object(
libc.src.errno.errno
)
+add_entrypoint_object(
+ nanbf16
+ SRCS
+ nanbf16.cpp
+ HDRS
+ ../nanbf16.h
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.__support.common
+ libc.src.__support.FPUtil.bfloat16
+ libc.src.__support.libc_errno
+ libc.src.__support.macros.config
+ libc.src.__support.macros.properties.types
+ libc.src.__support.str_to_float
+)
+
add_entrypoint_object(
nextafter
SRCS
diff --git a/libc/src/math/generic/nanbf16.cpp b/libc/src/math/generic/nanbf16.cpp
new file mode 100644
index 0000000000000..678dd6aed9ee3
--- /dev/null
+++ b/libc/src/math/generic/nanbf16.cpp
@@ -0,0 +1,25 @@
+//===-- Implementation of nanbf16 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/nanbf16.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/str_to_float.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, nanbf16, (const char *arg)) {
+ auto result = internal::strtonan<bfloat16>(arg);
+ if (result.has_error())
+ libc_errno = result.error;
+ return result.value;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/nanbf16.h b/libc/src/math/nanbf16.h
new file mode 100644
index 0000000000000..1551044677768
--- /dev/null
+++ b/libc/src/math/nanbf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for nanbf16 -----------------------*- 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_NANBF16_H
+#define LLVM_LIBC_SRC_MATH_NANBF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 nanbf16(const char *arg);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_NANBF16_H
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index a44f237cf0aad..65da1198a4044 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3515,6 +3515,22 @@ add_fp_unittest(
UNIT_TEST_ONLY
)
+add_fp_unittest(
+ nanbf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ nanbf16_test.cpp
+ DEPENDS
+ libc.hdr.signal_macros
+ libc.src.math.nanbf16
+ libc.src.__support.FPUtil.bfloat16
+ libc.src.__support.FPUtil.fp_bits
+ # FIXME: The nan tests currently have death tests, which aren't supported for
+ # hermetic tests.
+ UNIT_TEST_ONLY
+)
+
add_fp_unittest(
nearbyint_test
SUITE
diff --git a/libc/test/src/math/smoke/nanbf16_test.cpp b/libc/test/src/math/smoke/nanbf16_test.cpp
new file mode 100644
index 0000000000000..4154f6ed637c8
--- /dev/null
+++ b/libc/test/src/math/smoke/nanbf16_test.cpp
@@ -0,0 +1,55 @@
+//===-- Unittests for nanbf16 ---------------------------------------------===//
+//
+// 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/signal_macros.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/math/nanbf16.h"
+#include "test/UnitTest/FEnvSafeTest.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+class LlvmLibcNanf16Test : public LIBC_NAMESPACE::testing::FEnvSafeTest {
+public:
+ using StorageType = LIBC_NAMESPACE::fputil::FPBits<bfloat16>::StorageType;
+
+ void run_test(const char *input_str, StorageType bits) {
+ bfloat16 result = LIBC_NAMESPACE::nanbf16(input_str);
+ auto actual_fp = LIBC_NAMESPACE::fputil::FPBits<bfloat16>(result);
+ auto expected_fp = LIBC_NAMESPACE::fputil::FPBits<bfloat16>(bits);
+ EXPECT_EQ(actual_fp.uintval(), expected_fp.uintval());
+ }
+};
+
+TEST_F(LlvmLibcNanf16Test, NCharSeq) {
+ run_test("", 0x7fc0);
+
+ // 0x7fc0 + 0x1f (31) = 0x7cdf
+ run_test("31", 0x7fdf);
+
+ // 0x7fc0 + 0x15 = 0x7fd5
+ run_test("0x15", 0x7fd5);
+
+ run_test("1a", 0x7fc0);
+ run_test("1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM_",
+ 0x7fc0);
+ run_test("10000000000000000000000000000", 0x7fc0);
+}
+
+TEST_F(LlvmLibcNanf16Test, RandomString) {
+ run_test(" 1234", 0x7fc0);
+ run_test("-1234", 0x7fc0);
+ run_test("asd&f", 0x7fc0);
+ run_test("123 ", 0x7fc0);
+}
+
+#if defined(LIBC_ADD_NULL_CHECKS)
+TEST_F(LlvmLibcNanf16Test, InvalidInput) {
+ EXPECT_DEATH([] { LIBC_NAMESPACE::nanbf16(nullptr); }, WITH_SIGNAL(-1));
+}
+#endif // LIBC_ADD_NULL_CHECKS
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