[libc-commits] [libc] [llvm] [libc][math] Refactor tanpif16 to header-only (PR #181240)
Weiwen He via libc-commits
libc-commits at lists.llvm.org
Sun Feb 15 01:33:51 PST 2026
https://github.com/he-weiwen updated https://github.com/llvm/llvm-project/pull/181240
>From 8677f9871f6c5a1da884d8e0df002dc862bf05e9 Mon Sep 17 00:00:00 2001
From: he-weiwen <he.weiwen at outlook.com>
Date: Thu, 12 Feb 2026 13:29:01 +0000
Subject: [PATCH] [libc][math] Refactor tanpif16 to header-only
---
libc/shared/math.h | 1 +
libc/shared/math/tanpif16.h | 28 ++++
libc/src/__support/math/CMakeLists.txt | 18 +++
libc/src/__support/math/tanpif16.h | 126 ++++++++++++++++++
libc/src/math/generic/CMakeLists.txt | 10 +-
libc/src/math/generic/tanpif16.cpp | 100 +-------------
libc/test/shared/CMakeLists.txt | 1 +
libc/test/shared/shared_math_test.cpp | 1 +
.../llvm-project-overlay/libc/BUILD.bazel | 25 +++-
9 files changed, 196 insertions(+), 114 deletions(-)
create mode 100644 libc/shared/math/tanpif16.h
create mode 100644 libc/src/__support/math/tanpif16.h
diff --git a/libc/shared/math.h b/libc/shared/math.h
index e4487d7305e4b..9ec5915d9f09f 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -124,5 +124,6 @@
#include "math/tanf.h"
#include "math/tanhf.h"
#include "math/tanhf16.h"
+#include "math/tanpif16.h"
#endif // LLVM_LIBC_SHARED_MATH_H
diff --git a/libc/shared/math/tanpif16.h b/libc/shared/math/tanpif16.h
new file mode 100644
index 0000000000000..4a2dc4b530d6d
--- /dev/null
+++ b/libc/shared/math/tanpif16.h
@@ -0,0 +1,28 @@
+//===-- Implementation header for tanpif16 ----------------------*- 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_TANPIF16_H
+#define LLVM_LIBC_SHARED_MATH_TANPIF16_H
+
+#include "shared/libc_common.h"
+
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "src/__support/math/tanpif16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::tanpif16;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+
+#endif // LLVM_LIBC_SHARED_MATH_TANPIF_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 8027180e2cf08..4840a69fb5322 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -1786,3 +1786,21 @@ add_header_library(
libc.src.__support.macros.optimization
libc.include.llvm-libc-macros.float16_macros
)
+
+add_header_library(
+ tanpif16
+ HDRS
+ tanpif16.h
+ DEPENDS
+ .sincosf16_utils
+ libc.hdr.errno_macros
+ libc.hdr.fenv_macros
+ libc.include.llvm-libc-macros.float16_macros
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.except_value_utils.h
+ 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.macros.properties.types
+)
diff --git a/libc/src/__support/math/tanpif16.h b/libc/src/__support/math/tanpif16.h
new file mode 100644
index 0000000000000..1c3200f44e505
--- /dev/null
+++ b/libc/src/__support/math/tanpif16.h
@@ -0,0 +1,126 @@
+//===-- Implementation header for tanpif16 ----------------------*- 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_TANPIF16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_TANPIF16_H
+#include "include/llvm-libc-macros/float16-macros.h"
+#ifdef LIBC_TYPES_HAS_FLOAT16
+
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "sincosf16_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.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/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+namespace tanpif16_internal {
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+LIBC_INLINE_VAR constexpr size_t N_EXCEPTS = 21;
+
+LIBC_INLINE_VAR constexpr fputil::ExceptValues<float16, N_EXCEPTS>
+ TANPIF16_EXCEPTS{{
+ // (input, RZ output, RU offset, RD offset, RN offset)
+ {0x07f2, 0x0e3d, 1, 0, 0}, {0x086a, 0x0eee, 1, 0, 1},
+ {0x08db, 0x0fa0, 1, 0, 0}, {0x094c, 0x1029, 1, 0, 0},
+ {0x0b10, 0x118c, 1, 0, 0}, {0x1ce0, 0x23a8, 1, 0, 1},
+ {0x1235, 0x18e0, 1, 0, 0}, {0x2579, 0x2c4e, 1, 0, 0},
+ {0x28b2, 0x2f68, 1, 0, 1}, {0x2a43, 0x30f4, 1, 0, 1},
+ {0x31b7, 0x3907, 1, 0, 0}, {0x329d, 0x3a12, 1, 0, 1},
+ {0x34f1, 0x3dd7, 1, 0, 0}, {0x3658, 0x41ee, 1, 0, 0},
+ {0x38d4, 0xc1ee, 0, 1, 0}, {0x3d96, 0x41ee, 1, 0, 0},
+ {0x3e6a, 0xc1ee, 0, 1, 0}, {0x40cb, 0x41ee, 1, 0, 0},
+ {0x4135, 0xc1ee, 0, 1, 0}, {0x42cb, 0x41ee, 1, 0, 0},
+ {0x4335, 0xc1ee, 0, 1, 0},
+ }};
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+} // namespace tanpif16_internal
+
+LIBC_INLINE constexpr float16 tanpif16(float16 x) {
+ using namespace sincosf16_internal;
+ using namespace tanpif16_internal;
+ using FPBits = typename fputil::FPBits<float16>;
+ FPBits xbits(x);
+
+ uint16_t x_u = xbits.uintval();
+ uint16_t x_abs = x_u & 0x7fff;
+
+ // Handle exceptional values
+ if (LIBC_UNLIKELY(x_abs <= 0x4335)) {
+ if (LIBC_UNLIKELY(x_abs == 0U))
+ return x;
+
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+ bool x_sign = x_u >> 15;
+
+ if (auto r = TANPIF16_EXCEPTS.lookup_odd(x_abs, x_sign);
+ LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+ }
+
+ // Numbers greater or equal to 2^10 are integers, or infinity, or NaN
+ if (LIBC_UNLIKELY(x_abs >= 0x6400)) {
+ // Check for NaN or infinity values
+ if (LIBC_UNLIKELY(x_abs >= 0x7c00)) {
+ if (xbits.is_signaling_nan()) {
+ fputil::raise_except_if_required(FE_INVALID);
+ return FPBits::quiet_nan().get_val();
+ }
+ // is inf
+ if (x_abs == 0x7c00) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_INVALID);
+ }
+
+ return x + FPBits::quiet_nan().get_val();
+ }
+
+ return FPBits::zero(xbits.sign()).get_val();
+ }
+ // Range reduction:
+ // For |x| > 1/32, we perform range reduction as follows:
+ // Find k and y such that:
+ // x = (k + y) * 1/32
+ // k is an integer
+ // |y| < 0.5
+ //
+ // This is done by performing:
+ // k = round(x * 32)
+ // y = x * 32 - k
+ //
+ // Once k and y are computed, we then deduce the answer by the formula:
+ // tan(x) = sin(x) / cos(x)
+ // = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k)
+ float xf = x;
+ float sin_k = 0, cos_k = 0, sin_y = 0, cosm1_y = 0;
+ sincospif16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
+
+ if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
+ fputil::set_errno_if_required(EDOM);
+ fputil::raise_except_if_required(FE_DIVBYZERO);
+
+ int16_t x_mp5_u = static_cast<int16_t>(x - 0.5);
+ return ((x_mp5_u & 0x1) ? -1 : 1) * FPBits::inf().get_val();
+ }
+
+ using fputil::multiply_add;
+ return fputil::cast<float16>(
+ multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) /
+ multiply_add(sin_y, -sin_k, multiply_add(cosm1_y, cos_k, cos_k)));
+}
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LIBC_TYPES_HAS_FLOAT16
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_TANPIF16_H
\ No newline at end of file
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index b7c1f5a911831..f43ff3151b9ed 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -509,15 +509,7 @@ add_entrypoint_object(
HDRS
../tanpif16.h
DEPENDS
- 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.except_value_utils
- libc.src.__support.FPUtil.multiply_add
- libc.src.__support.macros.optimization
- libc.src.__support.math.sincosf16_utils
+ libc.src.__support.math.tanpif16
)
add_entrypoint_object(
diff --git a/libc/src/math/generic/tanpif16.cpp b/libc/src/math/generic/tanpif16.cpp
index c8dbe9eaf7d6f..fda411717cef6 100644
--- a/libc/src/math/generic/tanpif16.cpp
+++ b/libc/src/math/generic/tanpif16.cpp
@@ -7,108 +7,12 @@
//===----------------------------------------------------------------------===//
#include "src/math/tanpif16.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/cast.h"
-#include "src/__support/FPUtil/except_value_utils.h"
-#include "src/__support/FPUtil/multiply_add.h"
-#include "src/__support/macros/optimization.h"
-#include "src/__support/math/sincosf16_utils.h"
+#include "src/__support/math/tanpif16.h"
namespace LIBC_NAMESPACE_DECL {
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-constexpr size_t N_EXCEPTS = 21;
-
-constexpr fputil::ExceptValues<float16, N_EXCEPTS> TANPIF16_EXCEPTS{{
- // (input, RZ output, RU offset, RD offset, RN offset)
- {0x07f2, 0x0e3d, 1, 0, 0}, {0x086a, 0x0eee, 1, 0, 1},
- {0x08db, 0x0fa0, 1, 0, 0}, {0x094c, 0x1029, 1, 0, 0},
- {0x0b10, 0x118c, 1, 0, 0}, {0x1ce0, 0x23a8, 1, 0, 1},
- {0x1235, 0x18e0, 1, 0, 0}, {0x2579, 0x2c4e, 1, 0, 0},
- {0x28b2, 0x2f68, 1, 0, 1}, {0x2a43, 0x30f4, 1, 0, 1},
- {0x31b7, 0x3907, 1, 0, 0}, {0x329d, 0x3a12, 1, 0, 1},
- {0x34f1, 0x3dd7, 1, 0, 0}, {0x3658, 0x41ee, 1, 0, 0},
- {0x38d4, 0xc1ee, 0, 1, 0}, {0x3d96, 0x41ee, 1, 0, 0},
- {0x3e6a, 0xc1ee, 0, 1, 0}, {0x40cb, 0x41ee, 1, 0, 0},
- {0x4135, 0xc1ee, 0, 1, 0}, {0x42cb, 0x41ee, 1, 0, 0},
- {0x4335, 0xc1ee, 0, 1, 0},
-}};
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
LLVM_LIBC_FUNCTION(float16, tanpif16, (float16 x)) {
- using namespace math::sincosf16_internal;
- using FPBits = typename fputil::FPBits<float16>;
- FPBits xbits(x);
-
- uint16_t x_u = xbits.uintval();
- uint16_t x_abs = x_u & 0x7fff;
-
- // Handle exceptional values
- if (LIBC_UNLIKELY(x_abs <= 0x4335)) {
- if (LIBC_UNLIKELY(x_abs == 0U))
- return x;
-
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
- bool x_sign = x_u >> 15;
-
- if (auto r = TANPIF16_EXCEPTS.lookup_odd(x_abs, x_sign);
- LIBC_UNLIKELY(r.has_value()))
- return r.value();
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
- }
-
- // Numbers greater or equal to 2^10 are integers, or infinity, or NaN
- if (LIBC_UNLIKELY(x_abs >= 0x6400)) {
- // Check for NaN or infinity values
- if (LIBC_UNLIKELY(x_abs >= 0x7c00)) {
- if (xbits.is_signaling_nan()) {
- fputil::raise_except_if_required(FE_INVALID);
- return FPBits::quiet_nan().get_val();
- }
- // is inf
- if (x_abs == 0x7c00) {
- fputil::set_errno_if_required(EDOM);
- fputil::raise_except_if_required(FE_INVALID);
- }
-
- return x + FPBits::quiet_nan().get_val();
- }
-
- return FPBits::zero(xbits.sign()).get_val();
- }
- // Range reduction:
- // For |x| > 1/32, we perform range reduction as follows:
- // Find k and y such that:
- // x = (k + y) * 1/32
- // k is an integer
- // |y| < 0.5
- //
- // This is done by performing:
- // k = round(x * 32)
- // y = x * 32 - k
- //
- // Once k and y are computed, we then deduce the answer by the formula:
- // tan(x) = sin(x) / cos(x)
- // = (sin_y * cos_k + cos_y * sin_k) / (cos_y * cos_k - sin_y * sin_k)
- float xf = x;
- float sin_k, cos_k, sin_y, cosm1_y;
- sincospif16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
-
- if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
- fputil::set_errno_if_required(EDOM);
- fputil::raise_except_if_required(FE_DIVBYZERO);
-
- int16_t x_mp5_u = static_cast<int16_t>(x - 0.5);
- return ((x_mp5_u & 0x1) ? -1 : 1) * FPBits::inf().get_val();
- }
-
- using fputil::multiply_add;
- return fputil::cast<float16>(
- multiply_add(sin_y, cos_k, multiply_add(cosm1_y, sin_k, sin_k)) /
- multiply_add(sin_y, -sin_k, multiply_add(cosm1_y, cos_k, cos_k)));
+ return math::tanpif16(x);
}
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 1a0559af51acd..ec9baa64cd6b4 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -121,4 +121,5 @@ add_fp_unittest(
libc.src.__support.math.tanf
libc.src.__support.math.tanhf
libc.src.__support.math.tanhf16
+ libc.src.__support.math.tanpif16
)
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index fc6e6c74b3720..e0caa71c9b292 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -74,6 +74,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat16) {
EXPECT_FP_EQ(0x1p+0f16, LIBC_NAMESPACE::shared::f16sqrtl(1.0L));
EXPECT_FP_EQ(0.0f16, LIBC_NAMESPACE::shared::sinf16(0.0f16));
EXPECT_FP_EQ(0.0f16, LIBC_NAMESPACE::shared::tanhf16(0.0f16));
+ EXPECT_FP_EQ(0x0p+0f16, LIBC_NAMESPACE::shared::tanpif16(0.0f16));
}
#endif // LIBC_TYPES_HAS_FLOAT16
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 0eaff89f04215..08575e9dbe065 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -3950,6 +3950,23 @@ libc_support_library(
],
)
+libc_support_library(
+ name = "__support_math_tanpif16",
+ hdrs = ["src/__support/math/tanpif16.h"],
+ deps = [
+ ":__support_fputil_cast",
+ ":__support_fputil_except_value_utils",
+ ":__support_fputil_fenv_impl",
+ ":__support_fputil_fp_bits",
+ ":__support_fputil_multiply_add",
+ ":__support_macros_optimization",
+ ":__support_math_sincosf16_utils",
+ ":hdr_errno_macros",
+ ":hdr_fenv_macros",
+ ":llvm_libc_macros_float16_macros",
+ ],
+)
+
libc_support_library(
name = "__support_math_tanhf",
hdrs = ["src/__support/math/tanhf.h"],
@@ -5505,13 +5522,7 @@ libc_math_function(
libc_math_function(
name = "tanpif16",
- additional_deps = [
- ":__support_math_sincosf16_utils",
- ":hdr_errno_macros",
- ":hdr_fenv_macros",
- ":__support_fputil_cast",
- ":__support_fputil_multiply_add",
- ],
+ additional_deps = [":__support_math_tanpif16"],
)
libc_math_function(name = "totalorder")
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