[libc-commits] [libc] ee3e17d - [libc][math][c23] Add acoshf16 C23 math function. (#130588)
via libc-commits
libc-commits at lists.llvm.org
Sat Mar 22 19:08:38 PDT 2025
Author: Harrison Hao
Date: 2025-03-22T22:08:34-04:00
New Revision: ee3e17d67f6ce37a4a78d023a361c10d7398e15f
URL: https://github.com/llvm/llvm-project/commit/ee3e17d67f6ce37a4a78d023a361c10d7398e15f
DIFF: https://github.com/llvm/llvm-project/commit/ee3e17d67f6ce37a4a78d023a361c10d7398e15f.diff
LOG: [libc][math][c23] Add acoshf16 C23 math function. (#130588)
Implementation of acoshf16 function for 16-bit inputs.
Added:
libc/src/math/acoshf16.h
libc/src/math/generic/acoshf16.cpp
libc/test/src/math/acoshf16_test.cpp
libc/test/src/math/smoke/acoshf16_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/docs/headers/math/index.rst
libc/include/math.yaml
libc/src/math/CMakeLists.txt
libc/src/math/generic/CMakeLists.txt
libc/test/src/math/CMakeLists.txt
libc/test/src/math/smoke/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 5c4913a658c2f..52707fcadab61 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -645,6 +645,7 @@ endif()
if(LIBC_TYPES_HAS_FLOAT16)
list(APPEND TARGET_LIBM_ENTRYPOINTS
# math.h C23 _Float16 entrypoints
+ libc.src.math.acoshf16
libc.src.math.canonicalizef16
libc.src.math.ceilf16
libc.src.math.copysignf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 124b80d03d846..45dc087b2243a 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -654,6 +654,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
# math.h C23 _Float16 entrypoints
libc.src.math.asinf16
libc.src.math.acosf16
+ libc.src.math.acoshf16
libc.src.math.canonicalizef16
libc.src.math.ceilf16
libc.src.math.copysignf16
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
index 85585f4fc5f3d..b271a3d6f03b0 100644
--- a/libc/docs/headers/math/index.rst
+++ b/libc/docs/headers/math/index.rst
@@ -251,7 +251,7 @@ Higher Math Functions
+===========+==================+=================+========================+======================+========================+========================+============================+
| acos | |check| | | | |check| | | 7.12.4.1 | F.10.1.1 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| acosh | |check| | | | | | 7.12.5.1 | F.10.2.1 |
+| acosh | |check| | | | |check| | | 7.12.5.1 | F.10.2.1 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
| acospi | | | | | | 7.12.4.8 | F.10.1.8 |
+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/include/math.yaml b/libc/include/math.yaml
index fbfc51348411a..dcf307c7281c7 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -27,6 +27,13 @@ functions:
return_type: float
arguments:
- type: float
+ name: acoshf16
+ standards:
+ - stdc
+ return_type: _Float16
+ arguments:
+ - type: _Float16
+ guard: LIBC_TYPES_HAS_FLOAT16
- name: asin
standards:
- stdc
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index f18a73d46f9aa..bdf8b923416d8 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -46,6 +46,7 @@ add_math_entrypoint_object(acosf16)
add_math_entrypoint_object(acosh)
add_math_entrypoint_object(acoshf)
+add_math_entrypoint_object(acoshf16)
add_math_entrypoint_object(asin)
add_math_entrypoint_object(asinf)
diff --git a/libc/src/math/acoshf16.h b/libc/src/math/acoshf16.h
new file mode 100644
index 0000000000000..f471ecfeb6154
--- /dev/null
+++ b/libc/src/math/acoshf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for acoshf16 ----------------------*- 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_ACOSHF16_H
+#define LLVM_LIBC_SRC_MATH_ACOSHF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 acoshf16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_ACOSHF16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index db07bd1a098cc..0d532f0744016 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -3944,6 +3944,27 @@ add_entrypoint_object(
libc.src.__support.macros.optimization
)
+add_entrypoint_object(
+ acoshf16
+ SRCS
+ acoshf16.cpp
+ HDRS
+ ../acoshf16.h
+ DEPENDS
+ .explogxf
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.except_value_utils
+ libc.src.__support.FPUtil.fenv_impl
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.__support.FPUtil.multiply_add
+ libc.src.__support.FPUtil.polyeval
+ libc.src.__support.FPUtil.sqrt
+ libc.src.__support.macros.optimization
+ libc.src.__support.macros.properties.types
+)
+
add_entrypoint_object(
asinhf
SRCS
diff --git a/libc/src/math/generic/acoshf16.cpp b/libc/src/math/generic/acoshf16.cpp
new file mode 100644
index 0000000000000..44783a8749ac2
--- /dev/null
+++ b/libc/src/math/generic/acoshf16.cpp
@@ -0,0 +1,110 @@
+//===-- Half-precision acosh(x) 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/acoshf16.h"
+#include "explogxf.h"
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static constexpr size_t N_EXCEPTS = 2;
+static constexpr fputil::ExceptValues<float16, N_EXCEPTS> ACOSHF16_EXCEPTS{{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ // x = 0x1.6dcp+1, acoshf16(x) = 0x1.b6p+0 (RZ)
+ {0x41B7, 0x3ED8, 1, 0, 0},
+ // x = 0x1.39p+0, acoshf16(x) = 0x1.4f8p-1 (RZ)
+ {0x3CE4, 0x393E, 1, 0, 1},
+}};
+
+LLVM_LIBC_FUNCTION(float16, acoshf16, (float16 x)) {
+ using FPBits = fputil::FPBits<float16>;
+ FPBits xbits(x);
+ uint16_t x_u = xbits.uintval();
+
+ // Check for NaN input first.
+ if (LIBC_UNLIKELY(xbits.is_inf_or_nan())) {
+ if (xbits.is_signaling_nan()) {
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ if (xbits.is_neg()) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ return x;
+ }
+
+ // Domain error for inputs less than 1.0.
+ if (LIBC_UNLIKELY(x <= 1.0f)) {
+ if (x == 1.0f)
+ return FPBits::zero().get_val();
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+
+ if (auto r = ACOSHF16_EXCEPTS.lookup(xbits.uintval());
+ LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+
+ float xf = x;
+ // High-precision polynomial approximation for inputs close to 1.0
+ // ([1, 1.25)).
+ //
+ // Brief derivation:
+ // 1. Expand acosh(1 + delta) using Taylor series around delta=0:
+ // acosh(1 + delta) ≈ sqrt(2 * delta) * [1 - delta/12 + 3*delta^2/160
+ // - 5*delta^3/896 + 35*delta^4/18432 + ...]
+ // 2. Truncate the series to fit accurately for delta in [0, 0.25].
+ // 3. Polynomial coefficients (from sollya) used here are:
+ // P(delta) ≈ 1 - 0x1.555556p-4 * delta + 0x1.333334p-6 * delta^2
+ // - 0x1.6db6dcp-8 * delta^3 + 0x1.f1c71cp-10 * delta^4
+ // 4. The Sollya commands used to generate these coefficients were:
+ // > display = hexadecimal;
+ // > round(1/12, SG, RN);
+ // > round(3/160, SG, RN);
+ // > round(5/896, SG, RN);
+ // > round(35/18432, SG, RN);
+ // With hexadecimal display mode enabled, the outputs were:
+ // 0x1.555556p-4
+ // 0x1.333334p-6
+ // 0x1.6db6dcp-8
+ // 0x1.f1c71cp-10
+ // 5. The maximum absolute error, estimated using:
+ // dirtyinfnorm(acosh(1 + x) - sqrt(2*x) * P(x), [0, 0.25])
+ // is:
+ // 0x1.d84281p-22
+ if (LIBC_UNLIKELY(x_u < 0x3D00U)) {
+ float delta = xf - 1.0f;
+ float sqrt_2_delta = fputil::sqrt<float>(2.0 * delta);
+ float pe = fputil::polyeval(delta, 0x1p+0f, -0x1.555556p-4f, 0x1.333334p-6f,
+ -0x1.6db6dcp-8f, 0x1.f1c71cp-10f);
+ float approx = sqrt_2_delta * pe;
+ return fputil::cast<float16>(approx);
+ }
+
+ // acosh(x) = log(x + sqrt(x^2 - 1))
+ float sqrt_term = fputil::sqrt<float>(fputil::multiply_add(xf, xf, -1.0f));
+ float result = static_cast<float>(log_eval(xf + sqrt_term));
+
+ return fputil::cast<float16>(result);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index beafa87e03a77..f795f6bd55314 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -2173,6 +2173,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ acoshf16_test
+ NEED_MPFR
+ SUITE
+ libc-math-unittests
+ SRCS
+ acoshf16_test.cpp
+ DEPENDS
+ libc.src.math.acoshf16
+)
+
add_fp_unittest(
asinf_test
NEED_MPFR
diff --git a/libc/test/src/math/acoshf16_test.cpp b/libc/test/src/math/acoshf16_test.cpp
new file mode 100644
index 0000000000000..7348018396bd7
--- /dev/null
+++ b/libc/test/src/math/acoshf16_test.cpp
@@ -0,0 +1,28 @@
+//===-- Unittests for acoshf16 --------------------------------------------===//
+//
+// 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/errno/libc_errno.h"
+#include "src/math/acoshf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+#include <stdint.h>
+
+using LlvmLibcAcoshf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+static constexpr uint16_t START = 0x3c00U;
+static constexpr uint16_t STOP = 0x7c00;
+
+TEST_F(LlvmLibcAcoshf16Test, PositiveRange) {
+ for (uint16_t v = START; v <= STOP; ++v) {
+ float16 x = FPBits(v).get_val();
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Acosh, x,
+ LIBC_NAMESPACE::acoshf16(x), 0.5);
+ }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 94ec099ddfcbc..ddc9dd696a2bc 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3945,6 +3945,18 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ acoshf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ acoshf16_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.math.acoshf16
+ libc.src.__support.FPUtil.cast
+)
+
add_fp_unittest(
asinf_test
SUITE
diff --git a/libc/test/src/math/smoke/acoshf16_test.cpp b/libc/test/src/math/smoke/acoshf16_test.cpp
new file mode 100644
index 0000000000000..7681c2a4e7fbc
--- /dev/null
+++ b/libc/test/src/math/smoke/acoshf16_test.cpp
@@ -0,0 +1,70 @@
+//===-- Unittests for acoshf16 --------------------------------------------===//
+//
+// 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/cast.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/acoshf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcAcoshf16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcAcoshf16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::libc_errno = 0;
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::acoshf16(aNaN));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::acoshf16(sNaN), FE_INVALID);
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::acoshf16(zero), FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::acoshf16(neg_zero));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::acoshf16(neg_zero),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(inf, LIBC_NAMESPACE::acoshf16(inf));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::acoshf16(neg_inf));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::acoshf16(neg_inf),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ(zero, LIBC_NAMESPACE::acoshf16(
+ LIBC_NAMESPACE::fputil::cast<float16>(1.0)));
+ EXPECT_MATH_ERRNO(0);
+
+ EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::acoshf16(
+ LIBC_NAMESPACE::fputil::cast<float16>(0.5)));
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(
+ aNaN,
+ LIBC_NAMESPACE::acoshf16(LIBC_NAMESPACE::fputil::cast<float16>(-1.0)),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(
+ aNaN,
+ LIBC_NAMESPACE::acoshf16(LIBC_NAMESPACE::fputil::cast<float16>(-2.0)),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+
+ EXPECT_FP_EQ_WITH_EXCEPTION(
+ aNaN,
+ LIBC_NAMESPACE::acoshf16(LIBC_NAMESPACE::fputil::cast<float16>(-3.0)),
+ FE_INVALID);
+ EXPECT_MATH_ERRNO(EDOM);
+}
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