[llvm-branch-commits] [libc] [libc][math][c23] Add exp10m1f16 C23 math function (PR #105706)

via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Thu Aug 22 11:01:43 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: OverMighty (overmighty)

<details>
<summary>Changes</summary>

Part of #<!-- -->95250.

---

Patch is 25.01 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/105706.diff


16 Files Affected:

- (modified) libc/config/gpu/entrypoints.txt (+1) 
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1) 
- (modified) libc/docs/math/index.rst (+1-1) 
- (modified) libc/spec/stdc.td (+2) 
- (modified) libc/src/math/CMakeLists.txt (+2) 
- (added) libc/src/math/exp10m1f16.h (+21) 
- (modified) libc/src/math/generic/CMakeLists.txt (+22) 
- (modified) libc/src/math/generic/exp10f16.cpp (+2-43) 
- (added) libc/src/math/generic/exp10m1f16.cpp (+162) 
- (modified) libc/src/math/generic/expxf16.h (+47) 
- (modified) libc/test/src/math/CMakeLists.txt (+11) 
- (added) libc/test/src/math/exp10m1f16_test.cpp (+40) 
- (modified) libc/test/src/math/smoke/CMakeLists.txt (+12) 
- (added) libc/test/src/math/smoke/exp10m1f16_test.cpp (+109) 
- (modified) libc/utils/MPFRWrapper/MPFRUtils.cpp (+25) 
- (modified) libc/utils/MPFRWrapper/MPFRUtils.h (+1) 


``````````diff
diff --git a/libc/config/gpu/entrypoints.txt b/libc/config/gpu/entrypoints.txt
index d7f35bc1edf5a0..7c9a509647363e 100644
--- a/libc/config/gpu/entrypoints.txt
+++ b/libc/config/gpu/entrypoints.txt
@@ -486,6 +486,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.ceilf16
     libc.src.math.copysignf16
     libc.src.math.exp10f16
+    libc.src.math.exp10m1f16
     libc.src.math.exp2f16
     libc.src.math.expf16
     libc.src.math.f16add
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 06ca526c671ea8..cc09c08ba1fddf 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -595,6 +595,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.ceilf16
     libc.src.math.copysignf16
     libc.src.math.exp10f16
+    libc.src.math.exp10m1f16
     libc.src.math.exp2f16
     libc.src.math.exp2m1f16
     libc.src.math.expf16
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 0d2bbdd3381d19..19f933ed2fe2b5 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -288,7 +288,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | exp10     | |check|          | |check|         |                        | |check|              |                        | 7.12.6.2               | F.10.3.2                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| exp10m1   |                  |                 |                        |                      |                        | 7.12.6.3               | F.10.3.3                   |
+| exp10m1   |                  |                 |                        | |check|              |                        | 7.12.6.3               | F.10.3.3                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | exp2      | |check|          | |check|         |                        | |check|              |                        | 7.12.6.4               | F.10.3.4                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index c75343d567d7f9..3415e5755c88c4 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -606,6 +606,8 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"exp10f", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
           GuardedFunctionSpec<"exp10f16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
 
+          GuardedFunctionSpec<"exp10m1f16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>], "LIBC_TYPES_HAS_FLOAT16">,
+
           FunctionSpec<"remainder", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
           FunctionSpec<"remainderf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,
           FunctionSpec<"remainderl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index bd18c68a5e2fd6..2a3c15efb379a7 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -121,6 +121,8 @@ add_math_entrypoint_object(exp10)
 add_math_entrypoint_object(exp10f)
 add_math_entrypoint_object(exp10f16)
 
+add_math_entrypoint_object(exp10m1f16)
+
 add_math_entrypoint_object(expm1)
 add_math_entrypoint_object(expm1f)
 add_math_entrypoint_object(expm1f16)
diff --git a/libc/src/math/exp10m1f16.h b/libc/src/math/exp10m1f16.h
new file mode 100644
index 00000000000000..e195bc431f2e14
--- /dev/null
+++ b/libc/src/math/exp10m1f16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for exp10m1f16 --------------------*- 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_EXP10M1F16_H
+#define LLVM_LIBC_SRC_MATH_EXP10M1F16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float16 exp10m1f16(float16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_EXP10M1F16_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index c565dd5cb04f5a..5199d8304f3ef9 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -1576,6 +1576,28 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  exp10m1f16
+  SRCS
+    exp10m1f16.cpp
+  HDRS
+    ../exp10m1f16.h
+  DEPENDS
+    .expxf16
+    libc.hdr.errno_macros
+    libc.hdr.fenv_macros
+    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.rounding_mode
+    libc.src.__support.macros.optimization
+    libc.src.__support.macros.properties.cpu_features
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   expm1
   SRCS
diff --git a/libc/src/math/generic/exp10f16.cpp b/libc/src/math/generic/exp10f16.cpp
index 9959f7450b591f..19e51da737feab 100644
--- a/libc/src/math/generic/exp10f16.cpp
+++ b/libc/src/math/generic/exp10f16.cpp
@@ -53,16 +53,6 @@ static constexpr fputil::ExceptValues<float16, N_EXP10F16_EXCEPTS>
 #endif
     }};
 
-// Generated by Sollya with the following commands:
-//   > display = hexadecimal;
-//   > round(log2(10), SG, RN);
-static constexpr float LOG2F_10 = 0x1.a934fp+1f;
-
-// Generated by Sollya with the following commands:
-//   > display = hexadecimal;
-//   > round(log10(2), SG, RN);
-static constexpr float LOG10F_2 = 0x1.344136p-2f;
-
 LLVM_LIBC_FUNCTION(float16, exp10f16, (float16 x)) {
   using FPBits = fputil::FPBits<float16>;
   FPBits x_bits(x);
@@ -131,39 +121,8 @@ LLVM_LIBC_FUNCTION(float16, exp10f16, (float16 x)) {
   if (auto r = EXP10F16_EXCEPTS.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
     return r.value();
 
-  // For -8 < x < 5, to compute 10^x, we perform the following range reduction:
-  // find hi, mid, lo, such that:
-  //   x = (hi + mid) * log2(10) + lo, in which
-  //     hi is an integer,
-  //     mid * 2^3 is an integer,
-  //     -2^(-4) <= lo < 2^(-4).
-  // In particular,
-  //   hi + mid = round(x * 2^3) * 2^(-3).
-  // Then,
-  //   10^x = 10^(hi + mid + lo) = 2^((hi + mid) * log2(10)) + 10^lo
-  // We store 2^mid in the lookup table EXP2_MID_BITS, and compute 2^hi * 2^mid
-  // by adding hi to the exponent field of 2^mid.  10^lo is computed using a
-  // degree-4 minimax polynomial generated by Sollya.
-
-  float xf = x;
-  float kf = fputil::nearest_integer(xf * (LOG2F_10 * 0x1.0p+3f));
-  int x_hi_mid = static_cast<int>(kf);
-  int x_hi = x_hi_mid >> 3;
-  int x_mid = x_hi_mid & 0x7;
-  // lo = x - (hi + mid) = round(x * 2^3 * log2(10)) * log10(2) * (-2^(-3)) + x
-  float lo = fputil::multiply_add(kf, LOG10F_2 * -0x1.0p-3f, xf);
-
-  uint32_t exp2_hi_mid_bits =
-      EXP2_MID_BITS[x_mid] +
-      static_cast<uint32_t>(x_hi << fputil::FPBits<float>::FRACTION_LEN);
-  float exp2_hi_mid = fputil::FPBits<float>(exp2_hi_mid_bits).get_val();
-  // Degree-4 minimax polynomial generated by Sollya with the following
-  // commands:
-  //   > display = hexadecimal;
-  //   > P = fpminimax((10^x - 1)/x, 3, [|SG...|], [-2^-4, 2^-4]);
-  //   > 1 + x * P;
-  float exp10_lo = fputil::polyeval(lo, 0x1p+0f, 0x1.26bb14p+1f, 0x1.53526p+1f,
-                                    0x1.04b434p+1f, 0x1.2bcf9ep+0f);
+  // 10^x = 2^((hi + mid) * log2(10)) * 10^lo
+  auto [exp2_hi_mid, exp10_lo] = exp10_range_reduction(x);
   return static_cast<float16>(exp2_hi_mid * exp10_lo);
 }
 
diff --git a/libc/src/math/generic/exp10m1f16.cpp b/libc/src/math/generic/exp10m1f16.cpp
new file mode 100644
index 00000000000000..30b905b17cdee8
--- /dev/null
+++ b/libc/src/math/generic/exp10m1f16.cpp
@@ -0,0 +1,162 @@
+//===-- Half-precision 10^x - 1 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/exp10m1f16.h"
+#include "expxf16.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/except_value_utils.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/rounding_mode.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/macros/properties/cpu_features.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static constexpr fputil::ExceptValues<float16, 3> EXP10M1F16_EXCEPTS_LO = {{
+    // (input, RZ output, RU offset, RD offset, RN offset)
+    // x = 0x1.5c4p-4, exp10m1f16(x) = 0x1.bacp-3 (RZ)
+    {0x2d71U, 0x32ebU, 1U, 0U, 0U},
+    // x = -0x1.5ep-13, exp10m1f16(x) = -0x1.92cp-12 (RZ)
+    {0x8978U, 0x8e4bU, 0U, 1U, 0U},
+    // x = -0x1.e2p-10, exp10m1f16(x) = -0x1.14cp-8 (RZ)
+    {0x9788U, 0x9c53U, 0U, 1U, 0U},
+}};
+
+#ifdef LIBC_TARGET_CPU_HAS_FMA
+static constexpr size_t N_EXP10M1F16_EXCEPTS_HI = 3;
+#else
+static constexpr size_t N_EXP10M1F16_EXCEPTS_HI = 6;
+#endif
+
+static constexpr fputil::ExceptValues<float16, N_EXP10M1F16_EXCEPTS_HI>
+    EXP10M1F16_EXCEPTS_HI = {{
+        // (input, RZ output, RU offset, RD offset, RN offset)
+        // x = 0x1.8f4p-2, exp10mf16(x) = 0x1.744p+0 (RZ)
+        {0x363dU, 0x3dd1U, 1U, 0U, 0U},
+        // x = 0x1.95cp-2, exp10mf16(x) = 0x1.7d8p+0 (RZ)
+        {0x3657U, 0x3df6U, 1U, 0U, 0U},
+        // x = 0x1.d04p-2, exp10mf16(x) = 0x1.d7p+0 (RZ)
+        {0x3741U, 0x3f5cU, 1U, 0U, 1U},
+#ifndef LIBC_TARGET_CPU_HAS_FMA
+        // x = 0x1.0cp+1, exp10mf16(x) = 0x1.ec4p+6 (RZ)
+        {0x4030U, 0x57b1U, 1U, 0U, 1U},
+        // x = 0x1.1b8p+1, exp10mf16(x) = 0x1.45cp+7 (RZ)
+        {0x406eU, 0x5917U, 1U, 0U, 1U},
+        // x = 0x1.2f4p+2, exp10mf16(x) = 0x1.ab8p+15 (RZ)
+        {0x44bdU, 0x7aaeU, 1U, 0U, 1U},
+#endif
+    }};
+
+LLVM_LIBC_FUNCTION(float16, exp10m1f16, (float16 x)) {
+  using FPBits = fputil::FPBits<float16>;
+  FPBits x_bits(x);
+
+  uint16_t x_u = x_bits.uintval();
+  uint16_t x_abs = x_u & 0x7fffU;
+
+  // When |x| <= 2^(-3), or |x| >= 11 * log10(2), or x is NaN.
+  if (LIBC_UNLIKELY(x_abs <= 0x3000U || x_abs >= 0x429fU)) {
+    // exp10m1(NaN) = NaN
+    if (x_bits.is_nan()) {
+      if (x_bits.is_signaling_nan()) {
+        fputil::raise_except_if_required(FE_INVALID);
+        return FPBits::quiet_nan().get_val();
+      }
+
+      return x;
+    }
+
+    // When x >= 16 * log10(2).
+    if (x_u >= 0x44d1U && x_bits.is_pos()) {
+      // exp10m1(+inf) = +inf
+      if (x_bits.is_inf())
+        return FPBits::inf().get_val();
+
+      switch (fputil::quick_get_round()) {
+      case FE_TONEAREST:
+      case FE_UPWARD:
+        fputil::set_errno_if_required(ERANGE);
+        fputil::raise_except_if_required(FE_OVERFLOW | FE_INEXACT);
+        return FPBits::inf().get_val();
+      default:
+        return FPBits::max_normal().get_val();
+      }
+    }
+
+    // When x < -11 * log10(2).
+    if (x_u > 0xc29fU) {
+      // exp10m1(-inf) = -1
+      if (x_bits.is_inf())
+        return FPBits::one(Sign::NEG).get_val();
+
+      // When x >= -0x1.ce4p+1, round(10^x - 1, HP, RN) = -0x1.ffcp-1.
+      if (x_u <= 0xc339U) {
+        return fputil::round_result_slightly_down(
+            static_cast<float16>(-0x1.ffcp-1));
+      }
+
+      // When x < -0x1.ce4p+1, round(10^x - 1, HP, RN) = -1.
+      switch (fputil::quick_get_round()) {
+      case FE_TONEAREST:
+      case FE_DOWNWARD:
+        return FPBits::one(Sign::NEG).get_val();
+      default:
+        return static_cast<float16>(-0x1.ffcp-1);
+      }
+    }
+
+    // When |x| <= 2^(-3).
+    if (x_abs <= 0x3000U) {
+      if (auto r = EXP10M1F16_EXCEPTS_LO.lookup(x_u);
+          LIBC_UNLIKELY(r.has_value()))
+        return r.value();
+
+      float xf = x;
+      // Degree-5 minimax polynomial generated by Sollya with the following
+      // commands:
+      //   > display = hexadecimal;
+      //   > P = fpminimax((10^x - 1)/x, 4, [|SG...|], [-2^-3, 2^-3]);
+      //   > x * P;
+      return static_cast<float16>(
+          xf * fputil::polyeval(xf, 0x1.26bb1cp+1f, 0x1.5351c8p+1f,
+                                0x1.04704p+1f, 0x1.2ce084p+0f, 0x1.14a6bep-1f));
+    }
+  }
+
+  // When x is 1, 2, or 3. These are hard-to-round cases with exact results.
+  // 10^4 - 1 = 9'999 is not exactly representable as a float16, but luckily the
+  // polynomial approximation gives the correct result for x = 4 in all
+  // rounding modes.
+  if (LIBC_UNLIKELY((x_u & ~(0x3c00U | 0x4000U | 0x4200U | 0x4400U)) == 0)) {
+    switch (x_u) {
+    case 0x3c00U: // x = 1.0f16
+      return static_cast<float16>(9.0);
+    case 0x4000U: // x = 2.0f16
+      return static_cast<float16>(99.0);
+    case 0x4200U: // x = 3.0f16
+      return static_cast<float16>(999.0);
+    }
+  }
+
+  if (auto r = EXP10M1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+    return r.value();
+
+  // exp10(x) = exp2((hi + mid) * log2(10)) * exp10(lo)
+  auto [exp2_hi_mid, exp10_lo] = exp10_range_reduction(x);
+  // exp10m1(x) = exp2((hi + mid) * log2(lo)) * exp10(lo) - 1
+  return static_cast<float16>(
+      fputil::multiply_add(exp2_hi_mid, exp10_lo, -1.0f));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/generic/expxf16.h b/libc/src/math/generic/expxf16.h
index 35294130a15007..8de329bd2ab07f 100644
--- a/libc/src/math/generic/expxf16.h
+++ b/libc/src/math/generic/expxf16.h
@@ -127,6 +127,53 @@ LIBC_INLINE ExpRangeReduction exp2_range_reduction(float16 x) {
   return {exp2_hi_mid, exp2_lo};
 }
 
+// Generated by Sollya with the following commands:
+//   > display = hexadecimal;
+//   > round(log2(10), SG, RN);
+static constexpr float LOG2F_10 = 0x1.a934fp+1f;
+
+// Generated by Sollya with the following commands:
+//   > display = hexadecimal;
+//   > round(log10(2), SG, RN);
+static constexpr float LOG10F_2 = 0x1.344136p-2f;
+
+LIBC_INLINE ExpRangeReduction exp10_range_reduction(float16 x) {
+  // For -8 < x < 5, to compute 10^x, we perform the following range reduction:
+  // find hi, mid, lo, such that:
+  //   x = (hi + mid) * log2(10) + lo, in which
+  //     hi is an integer,
+  //     mid * 2^3 is an integer,
+  //     -2^(-4) <= lo < 2^(-4).
+  // In particular,
+  //   hi + mid = round(x * 2^3) * 2^(-3).
+  // Then,
+  //   10^x = 10^(hi + mid + lo) = 2^((hi + mid) * log2(10)) + 10^lo
+  // We store 2^mid in the lookup table EXP2_MID_BITS, and compute 2^hi * 2^mid
+  // by adding hi to the exponent field of 2^mid.  10^lo is computed using a
+  // degree-4 minimax polynomial generated by Sollya.
+
+  float xf = x;
+  float kf = fputil::nearest_integer(xf * (LOG2F_10 * 0x1.0p+3f));
+  int x_hi_mid = static_cast<int>(kf);
+  int x_hi = x_hi_mid >> 3;
+  int x_mid = x_hi_mid & 0x7;
+  // lo = x - (hi + mid) = round(x * 2^3 * log2(10)) * log10(2) * (-2^(-3)) + x
+  float lo = fputil::multiply_add(kf, LOG10F_2 * -0x1.0p-3f, xf);
+
+  uint32_t exp2_hi_mid_bits =
+      EXP2_MID_BITS[x_mid] +
+      static_cast<uint32_t>(x_hi << fputil::FPBits<float>::FRACTION_LEN);
+  float exp2_hi_mid = fputil::FPBits<float>(exp2_hi_mid_bits).get_val();
+  // Degree-4 minimax polynomial generated by Sollya with the following
+  // commands:
+  //   > display = hexadecimal;
+  //   > P = fpminimax((10^x - 1)/x, 3, [|SG...|], [-2^-4, 2^-4]);
+  //   > 1 + x * P;
+  float exp10_lo = fputil::polyeval(lo, 0x1p+0f, 0x1.26bb14p+1f, 0x1.53526p+1f,
+                                    0x1.04b434p+1f, 0x1.2bcf9ep+0f);
+  return {exp2_hi_mid, exp10_lo};
+}
+
 } // namespace LIBC_NAMESPACE_DECL
 
 #endif // LLVM_LIBC_SRC_MATH_GENERIC_EXPXF16_H
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 07a9405081f97d..d2c9795afcd7f5 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -1051,6 +1051,17 @@ add_fp_unittest(
     libc.src.math.exp10f16
 )
 
+add_fp_unittest(
+  exp10m1f16_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    exp10m1f16_test.cpp
+  DEPENDS
+    libc.src.math.exp10m1f16
+)
+
 add_fp_unittest(
   copysign_test
   SUITE
diff --git a/libc/test/src/math/exp10m1f16_test.cpp b/libc/test/src/math/exp10m1f16_test.cpp
new file mode 100644
index 00000000000000..41bb12f7d0973a
--- /dev/null
+++ b/libc/test/src/math/exp10m1f16_test.cpp
@@ -0,0 +1,40 @@
+//===-- Exhaustive test for exp10m1f16 ------------------------------------===//
+//
+// 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/exp10m1f16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcExp10m1f16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf];
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7c00U;
+
+// Range: [-Inf, 0];
+static constexpr uint16_t NEG_START = 0x8000U;
+static constexpr uint16_t NEG_STOP = 0xfc00U;
+
+TEST_F(LlvmLibcExp10m1f16Test, PositiveRange) {
+  for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+    float16 x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp10m1, x,
+                                   LIBC_NAMESPACE::exp10m1f16(x), 0.5);
+  }
+}
+
+TEST_F(LlvmLibcExp10m1f16Test, NegativeRange) {
+  for (uint16_t v = NEG_START; v <= NEG_STOP; ++v) {
+    float16 x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp10m1, x,
+                                   LIBC_NAMESPACE::exp10m1f16(x), 0.5);
+  }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 349716d44cfb20..b941b090918d74 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -1153,6 +1153,18 @@ add_fp_unittest(
     libc.src.math.exp10f16
 )
 
+add_fp_unittest(
+  exp10m1f16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    exp10m1f16_test.cpp
+  DEPENDS
+    libc.hdr.fenv_macros
+    libc.src.errno.errno
+    libc.src.math.exp10m1f16
+)
+
 add_fp_unittest(
   copysign_test
   SUITE
diff --git a/libc/test/src/math/smoke/exp10m1f16_test.cpp b/libc/test/src/math/smoke/exp10m1f16_test.cpp
new file mode 100644
index 00000000000000..051f2befe02ed6
--- /dev/null
+++ b/libc/test/src/math/smoke/exp10m1f16_test.cpp
@@ -0,0 +1,109 @@
+//===-- Unittests for exp10m1f16 ------------------------------------------===//
+//
+// 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/fenv_macros.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/exp10m1f16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcExp10m1f16Test = LIBC_NAMESPACE::testing::FPTest<float16>;
+
+TEST_F(LlvmLibcExp10m1f16Test, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::exp10m1f16(aNaN));
+  EXPE...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/105706


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