[libc-commits] [libc] [libc][math] Add double-precision acosh, asinh, atanh, cosh, sinh, tanh (PR #199442)

via libc-commits libc-commits at lists.llvm.org
Sun May 24 12:41:13 PDT 2026 

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Aayush Shrivastava (iamaayushrivastava)

<details>
<summary>Changes</summary>

Add missing double-precision hyperbolic math functions to LLVM libc.

---

Patch is 56.17 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/199442.diff


30 Files Affected:

- (modified) libc/config/linux/x86_64/entrypoints.txt (+6) 
- (modified) libc/include/math.yaml (+51-1) 
- (modified) libc/src/__support/math/CMakeLists.txt (+79) 
- (added) libc/src/__support/math/acosh.h (+70) 
- (added) libc/src/__support/math/asinh.h (+79) 
- (added) libc/src/__support/math/atanh.h (+71) 
- (added) libc/src/__support/math/cosh.h (+72) 
- (added) libc/src/__support/math/sinh.h (+88) 
- (added) libc/src/__support/math/tanh.h (+70) 
- (modified) libc/src/math/generic/CMakeLists.txt (+60) 
- (added) libc/src/math/generic/acosh.cpp (+16) 
- (added) libc/src/math/generic/asinh.cpp (+16) 
- (added) libc/src/math/generic/atanh.cpp (+16) 
- (added) libc/src/math/generic/cosh.cpp (+16) 
- (added) libc/src/math/generic/sinh.cpp (+16) 
- (added) libc/src/math/generic/tanh.cpp (+16) 
- (modified) libc/test/src/math/CMakeLists.txt (+76) 
- (added) libc/test/src/math/acosh_test.cpp (+52) 
- (added) libc/test/src/math/asinh_test.cpp (+41) 
- (added) libc/test/src/math/atanh_test.cpp (+57) 
- (added) libc/test/src/math/cosh_test.cpp (+55) 
- (added) libc/test/src/math/sinh_test.cpp (+55) 
- (modified) libc/test/src/math/smoke/CMakeLists.txt (+70) 
- (added) libc/test/src/math/smoke/acosh_test.cpp (+61) 
- (added) libc/test/src/math/smoke/asinh_test.cpp (+52) 
- (added) libc/test/src/math/smoke/atanh_test.cpp (+65) 
- (added) libc/test/src/math/smoke/cosh_test.cpp (+72) 
- (added) libc/test/src/math/smoke/sinh_test.cpp (+69) 
- (added) libc/test/src/math/smoke/tanh_test.cpp (+52) 
- (added) libc/test/src/math/tanh_test.cpp (+40) 


``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 5545790fecd85..16d733fdde948 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -534,10 +534,12 @@ set(TARGET_LIBM_ENTRYPOINTS
     # math.h entrypoints
     libc.src.math.acos
     libc.src.math.acosf
+    libc.src.math.acosh
     libc.src.math.acoshf
     libc.src.math.acospif
     libc.src.math.asin
     libc.src.math.asinf
+    libc.src.math.asinh
     libc.src.math.asinhf
     libc.src.math.asinpi
     libc.src.math.asinpif
@@ -545,6 +547,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.atan2f
     libc.src.math.atan
     libc.src.math.atanf
+    libc.src.math.atanh
     libc.src.math.atanhf
     libc.src.math.canonicalize
     libc.src.math.canonicalizef
@@ -560,6 +563,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.copysignl
     libc.src.math.cos
     libc.src.math.cosf
+    libc.src.math.cosh
     libc.src.math.coshf
     libc.src.math.cospif
     libc.src.math.dfmal
@@ -746,6 +750,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.sincos
     libc.src.math.sincosf
     libc.src.math.sinf
+    libc.src.math.sinh
     libc.src.math.sinhf
     libc.src.math.sinpif
     libc.src.math.sqrt
@@ -753,6 +758,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.sqrtl
     libc.src.math.tan
     libc.src.math.tanf
+    libc.src.math.tanh
     libc.src.math.tanhf
     libc.src.math.tanpif
     libc.src.math.totalorder
diff --git a/libc/include/math.yaml b/libc/include/math.yaml
index e50be8f05cc65..a0c05a7cbf7fb 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -27,6 +27,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: acosh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: acoshf
     standards:
       - stdc
@@ -40,6 +46,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: acospif
+    standards:
+      - stdc
+    return_type: float
+    arguments:
+      - type: float
   - name: acospif16
     standards:
       - stdc
@@ -66,6 +78,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: asinh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: asinhf
     standards:
       - stdc
@@ -133,6 +151,14 @@ functions:
       - type: float128
       - type: float128
     guard: LIBC_TYPES_HAS_FLOAT128
+  - name: atan2f16
+    standards:
+      - stdc
+    return_type: _Float16
+    arguments:
+      - type: _Float16
+      - type: _Float16
+    guard: LIBC_TYPES_HAS_FLOAT16
   - name: atanf
     standards:
       - stdc
@@ -146,6 +172,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: atanh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: atanhf
     standards:
       - stdc
@@ -153,7 +185,7 @@ functions:
     arguments:
       - type: float
   - name: atanhf16
-    standatds:
+    standards:
       - stdc
     return_type: _Float16
     arguments:
@@ -303,6 +335,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: cosh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: coshf
     standards:
       - stdc
@@ -2593,6 +2631,12 @@ functions:
       - type: float
       - type: float *
       - type: float *
+  - name: sinh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: sinhf
     standards:
       - stdc
@@ -2670,6 +2714,12 @@ functions:
     arguments:
       - type: _Float16
     guard: LIBC_TYPES_HAS_FLOAT16
+  - name: tanh
+    standards:
+      - stdc
+    return_type: double
+    arguments:
+      - type: double
   - name: tanhf
     standards:
       - stdc
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 9e3ec26cdc881..ba940e2f61e98 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -67,6 +67,19 @@ add_header_library(
     libc.src.__support.macros.optimization
 )
 
+add_header_library(
+  acosh
+  HDRS
+    acosh.h
+  DEPENDS
+    .log
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.sqrt
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   acoshf
   HDRS
@@ -157,6 +170,20 @@ add_header_library(
     libc.src.__support.macros.properties.cpu_features
 )
 
+add_header_library(
+  asinh
+  HDRS
+    asinh.h
+  DEPENDS
+    .log
+    .log1p
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.sqrt
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   asinhf
   HDRS
@@ -354,6 +381,18 @@ add_header_library(
     libc.src.__support.macros.optimization
 )
 
+add_header_library(
+  atanh
+  HDRS
+    atanh.h
+  DEPENDS
+    .log1p
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   atanhf
   HDRS
@@ -2797,6 +2836,20 @@ add_header_library(
     libc.src.__support.macros.properties.types
 )
 
+add_header_library(
+  cosh
+  HDRS
+    cosh.h
+  DEPENDS
+    .exp
+    .expm1
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.rounding_mode
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   coshf
   HDRS
@@ -5221,6 +5274,20 @@ add_header_library(
     libc.src.__support.macros.properties.types
 )
 
+add_header_library(
+  sinh
+  HDRS
+    sinh.h
+  DEPENDS
+    .exp
+    .expm1
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.rounding_mode
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   sinhf
   HDRS
@@ -5371,6 +5438,18 @@ add_header_library(
     libc.include.llvm-libc-macros.float16_macros
 )
 
+add_header_library(
+  tanh
+  HDRS
+    tanh.h
+  DEPENDS
+    .expm1
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+)
+
 add_header_library(
   tanhf
   HDRS
diff --git a/libc/src/__support/math/acosh.h b/libc/src/__support/math/acosh.h
new file mode 100644
index 0000000000000..c25fed33f8791
--- /dev/null
+++ b/libc/src/__support/math/acosh.h
@@ -0,0 +1,70 @@
+//===-- Implementation header for acosh -------------------------*- 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_ACOSH_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_ACOSH_H
+
+#include "log.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE double acosh(double x) {
+  using FPBits = fputil::FPBits<double>;
+  FPBits xbits(x);
+
+  // acosh is only defined for x >= 1.
+  if (LIBC_UNLIKELY(x < 1.0)) {
+    if (x == x) {
+      // x < 1 and x is not NaN: domain error.
+      fputil::set_errno_if_required(EDOM);
+      fputil::raise_except_if_required(FE_INVALID);
+    } else {
+      // x is NaN.
+      if (xbits.is_signaling_nan()) {
+        fputil::raise_except_if_required(FE_INVALID);
+        return FPBits::quiet_nan().get_val();
+      }
+      return x;
+    }
+    return FPBits::quiet_nan().get_val();
+  }
+
+  // acosh(1) = 0.
+  if (x == 1.0)
+    return 0.0;
+
+  // acosh(+inf) = +inf.
+  if (LIBC_UNLIKELY(xbits.is_inf()))
+    return x;
+
+  uint64_t x_u = xbits.uintval();
+
+  // For large x (x >= 2^28), acosh(x) ~ log(2x) = log(x) + log(2).
+  if (LIBC_UNLIKELY(x_u >= 0x41b0000000000000ULL)) {
+    // log(2x) = log(x) + log(2).
+    constexpr double LOG_2 = 0x1.62e42fefa39efp-1;
+    return math::log(x) + LOG_2;
+  }
+
+  // General case: acosh(x) = log(x + sqrt(x^2 - 1)).
+  double x2m1 = x * x - 1.0;
+  return math::log(x + fputil::sqrt<double>(x2m1));
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ACOSH_H
diff --git a/libc/src/__support/math/asinh.h b/libc/src/__support/math/asinh.h
new file mode 100644
index 0000000000000..73d920ed4874c
--- /dev/null
+++ b/libc/src/__support/math/asinh.h
@@ -0,0 +1,79 @@
+//===-- Implementation header for asinh -------------------------*- 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_ASINH_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_ASINH_H
+
+#include "log.h"
+#include "log1p.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE double asinh(double x) {
+  using FPBits = fputil::FPBits<double>;
+  FPBits xbits(x);
+
+  // Handle NaN.
+  if (LIBC_UNLIKELY(xbits.is_nan())) {
+    if (xbits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    return x;
+  }
+
+  // Handle +/-inf: asinh(+/-inf) = +/-inf.
+  if (LIBC_UNLIKELY(xbits.is_inf()))
+    return x;
+
+  uint64_t x_abs_u = xbits.abs().uintval();
+  double x_abs = xbits.abs().get_val();
+  bool is_neg = xbits.is_neg();
+
+  // For very small |x| (|x| <= 2^-26), asinh(x) ~ x.
+  // Use FP arithmetic to ensure FTZ/DAZ mode behavior.
+  if (LIBC_UNLIKELY(x_abs_u <= 0x3e50000000000000ULL)) {
+    // asinh(+/-0) = +/-0, preserve sign of zero exactly.
+    if (LIBC_UNLIKELY(x_abs_u == 0))
+      return x;
+    double x2 = x_abs * x_abs;
+    double result = x_abs - x2 * x_abs * (1.0 / 6.0);
+    return is_neg ? -result : result;
+  }
+
+  double result;
+  // For large |x| (|x| >= 2^28), asinh(x) ~ log(2|x|) = log(|x|) + log(2).
+  if (LIBC_UNLIKELY(x_abs_u >= 0x41b0000000000000ULL)) {
+    constexpr double LOG_2 = 0x1.62e42fefa39efp-1;
+    result = math::log(x_abs) + LOG_2;
+  } else if (x_abs_u >= 0x3fe0000000000000ULL) {
+    // |x| >= 0.5: asinh(x) = log(x + sqrt(x^2 + 1)).
+    result = math::log(x_abs + fputil::sqrt<double>(x_abs * x_abs + 1.0));
+  } else {
+    // |x| < 0.5: use log1p for better accuracy near 0.
+    // asinh(x) = log1p(x + x^2 / (1 + sqrt(1 + x^2)))
+    double x2 = x_abs * x_abs;
+    double sqrt1px2 = fputil::sqrt<double>(1.0 + x2);
+    result = math::log1p(x_abs + x2 / (1.0 + sqrt1px2));
+  }
+
+  return is_neg ? -result : result;
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ASINH_H
diff --git a/libc/src/__support/math/atanh.h b/libc/src/__support/math/atanh.h
new file mode 100644
index 0000000000000..cf85fe721505c
--- /dev/null
+++ b/libc/src/__support/math/atanh.h
@@ -0,0 +1,71 @@
+//===-- Implementation header for atanh -------------------------*- 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_ATANH_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_ATANH_H
+
+#include "log1p.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE double atanh(double x) {
+  using FPBits = fputil::FPBits<double>;
+  FPBits xbits(x);
+  Sign sign = xbits.sign();
+  uint64_t x_abs_u = xbits.abs().uintval();
+
+  // Handle NaN.
+  if (LIBC_UNLIKELY(xbits.is_nan())) {
+    if (xbits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    return x;
+  }
+
+  // |x| >= 1.
+  if (LIBC_UNLIKELY(x_abs_u >= 0x3ff0000000000000ULL)) {
+    if (x_abs_u == 0x3ff0000000000000ULL) {
+      // |x| == 1: return +/-inf with ERANGE.
+      fputil::set_errno_if_required(ERANGE);
+      fputil::raise_except_if_required(FE_DIVBYZERO);
+      return FPBits::inf(sign).get_val();
+    }
+    // |x| > 1: domain error.
+    fputil::set_errno_if_required(EDOM);
+    fputil::raise_except_if_required(FE_INVALID);
+    return FPBits::quiet_nan().get_val();
+  }
+
+  // For very small |x| (|x| <= 2^-27), atanh(x) ~ x.
+  // Use FP arithmetic to ensure FTZ/DAZ mode behavior.
+  if (LIBC_UNLIKELY(x_abs_u <= 0x3e40000000000000ULL)) {
+    double x_abs = xbits.abs().get_val();
+    double x2 = x_abs * x_abs;
+    double result = x_abs + x2 * x_abs * (1.0 / 3.0);
+    return sign == Sign::NEG ? -result : result;
+  }
+
+  // General case: atanh(x) = 0.5 * log((1+x)/(1-x))
+  //                        = 0.5 * log1p(2x / (1-x))
+  double x_abs = xbits.abs().get_val();
+  double result = 0.5 * math::log1p(2.0 * x_abs / (1.0 - x_abs));
+  return sign == Sign::NEG ? -result : result;
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ATANH_H
diff --git a/libc/src/__support/math/cosh.h b/libc/src/__support/math/cosh.h
new file mode 100644
index 0000000000000..8c65e642b98c1
--- /dev/null
+++ b/libc/src/__support/math/cosh.h
@@ -0,0 +1,72 @@
+//===-- Implementation header for cosh --------------------------*- 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_COSH_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_COSH_H
+
+#include "exp.h"
+#include "expm1.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/rounding_mode.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE double cosh(double x) {
+  using FPBits = fputil::FPBits<double>;
+  FPBits xbits(x);
+  // cosh is even, work with |x|.
+  xbits.set_sign(Sign::POS);
+  x = xbits.get_val();
+
+  uint64_t x_u = xbits.uintval();
+
+  // Handle NaN: cosh(NaN) = NaN.
+  if (LIBC_UNLIKELY(xbits.is_nan())) {
+    if (xbits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    return x;
+  }
+
+  // cosh(+inf) = +inf.
+  if (LIBC_UNLIKELY(xbits.is_inf()))
+    return x + FPBits::inf().get_val();
+
+  // For very small |x| (|x| <= 2^-27), cosh(x) ~ 1.
+  if (LIBC_UNLIKELY(x_u <= 0x3e40000000000000ULL))
+    return 1.0 + x;
+
+  // For |x| >= 710, overflow.
+  // log(DBL_MAX) ~ 709.78, so exp overflows for x > ~709.78.
+  if (LIBC_UNLIKELY(x_u >= 0x4086340000000000ULL)) {
+    int rounding = fputil::quick_get_round();
+    if (rounding == FE_DOWNWARD || rounding == FE_TOWARDZERO)
+      return FPBits::max_normal().get_val();
+    fputil::set_errno_if_required(ERANGE);
+    fputil::raise_except_if_required(FE_OVERFLOW);
+    return x + FPBits::inf().get_val();
+  }
+
+  // cosh(x) = (exp(x) + exp(-x)) / 2.
+  // Use expm1 for small x to avoid cancellation:
+  // cosh(x) = 1 + expm1(x)^2 / (2 * (1 + expm1(x))) ... but for simplicity:
+  double ex = math::exp(x);
+  return (ex + 1.0 / ex) * 0.5;
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_COSH_H
diff --git a/libc/src/__support/math/sinh.h b/libc/src/__support/math/sinh.h
new file mode 100644
index 0000000000000..bbc7af2a5cacd
--- /dev/null
+++ b/libc/src/__support/math/sinh.h
@@ -0,0 +1,88 @@
+//===-- Implementation header for sinh --------------------------*- 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_SINH_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_SINH_H
+
+#include "exp.h"
+#include "expm1.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/rounding_mode.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+LIBC_INLINE double sinh(double x) {
+  using FPBits = fputil::FPBits<double>;
+  FPBits xbits(x);
+  bool is_neg = xbits.is_neg();
+  // Work with |x|.
+  xbits.set_sign(Sign::POS);
+  double x_abs = xbits.get_val();
+  uint64_t x_abs_u = xbits.uintval();
+
+  // Handle NaN: sinh(NaN) = NaN.
+  if (LIBC_UNLIKELY(xbits.is_nan())) {
+    if (xbits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    return x;
+  }
+
+  // sinh(+/-inf) = +/-inf.
+  if (LIBC_UNLIKELY(xbits.is_inf()))
+    return x;
+
+  // For very small |x| (|x| <= 2^-26), sinh(x) ~ x.
+  // Use FP arithmetic to ensure FTZ/DAZ mode behavior.
+  if (LIBC_UNLIKELY(x_abs_u <= 0x3e50000000000000ULL)) {
+    double x2 = x_abs * x_abs;
+    double result = x_abs + x2 * x_abs * (1.0 / 6.0);
+    return is_neg ? -result : result;
+  }
+
+  // For |x| >= 710, overflow.
+  if (LIBC_UNLIKELY(x_abs_u >= 0x4086340000000000ULL)) {
+    int rounding = fputil::quick_get_round();
+    if ((rounding == FE_DOWNWARD && !is_neg) ||
+        (rounding == FE_UPWARD && is_neg) || rounding == FE_TOWARDZERO)
+      return is_neg ? -FPBits::max_normal().get_val()
+                    : FPBits::max_normal().get_val();
+    fputil::set_errno_if_required(ERANGE);
+    fputil::raise_except_if_required(FE_OVERFLOW);
+    return x + (is_neg ? -FPBits::inf().get_val() : FPBits::inf().get_val());
+  }
+
+  double result;
+  // For small |x| (|x| < 1), use expm1 to avoid cancellation:
+  // sinh(x) = expm1(x) - expm1(x)^2 / (2*(1+expm1(x)))
+  //         = expm1(x) * (1 + expm1(x)) / (2*(1+expm1(x))) ... keep it simple:
+  // sinh(x) = (exp(x) - exp(-x)) / 2
+  if (x_abs_u < 0x3ff0000000000000ULL) {
+    // |x| < 1: use expm1 for accuracy.
+    double em1 = math::expm1(x_abs);
+    result = em1 / 2.0 + em1 / (2.0 * (1.0 + em1));
+  } else {
+    // |x| >= 1.
+    double ex = math::exp(x_abs);
+    result = (ex - 1.0 / ex) * 0.5;
+  }
+
+  return is_neg ? -result : result;
+}
+
+} // namespace math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_SINH_H
diff --git a/libc/src/__support/math/tanh.h b/libc/src/__support/math/tanh.h
new file mode 100644
index 0000000000000..7e0b47dac463f
--- /dev/null
+++ b/libc/src/__support/math/tanh.h
@@ -0,0 +1,70 @@
+//===-- Implementation header for tanh --------------------------*- 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
+//
+//===------------------...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/199442

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