[libc-commits] [libc] [libc][math][c23] Add exp10m1f C23 math function (PR #87992)

via libc-commits libc-commits at lists.llvm.org
Mon Apr 8 06:42:37 PDT 2024


https://github.com/overmighty created https://github.com/llvm/llvm-project/pull/87992

Fixes #86503.

cc @lntue

>From f2d0edab4aeb0aa48cc360e0ad9899fdb2ad099d Mon Sep 17 00:00:00 2001
From: OverMighty <its.overmighty at gmail.com>
Date: Mon, 8 Apr 2024 14:31:11 +0100
Subject: [PATCH] [libc][math][c23] Add exp10m1f C23 math function

Fixes #86503.
---
 libc/config/linux/x86_64/entrypoints.txt      |   1 +
 libc/docs/math/index.rst                      |   2 +-
 libc/spec/stdc.td                             |   2 +
 libc/src/math/CMakeLists.txt                  |   2 +
 libc/src/math/exp10m1f.h                      |  18 ++
 libc/src/math/generic/CMakeLists.txt          |  22 ++
 libc/src/math/generic/exp10m1f.cpp            | 215 ++++++++++++++++++
 libc/test/src/math/CMakeLists.txt             |  16 ++
 libc/test/src/math/exhaustive/CMakeLists.txt  |  15 ++
 .../src/math/exhaustive/exp10m1f_test.cpp     |  33 +++
 libc/test/src/math/exp10m1f_test.cpp          |  85 +++++++
 libc/test/src/math/exp2m1f_test.cpp           |  21 +-
 libc/test/src/math/smoke/CMakeLists.txt       |  11 +
 libc/test/src/math/smoke/exp10m1f_test.cpp    |  56 +++++
 libc/test/src/math/smoke/exp2m1f_test.cpp     |  10 +-
 libc/utils/MPFRWrapper/MPFRUtils.cpp          |  25 ++
 libc/utils/MPFRWrapper/MPFRUtils.h            |   1 +
 17 files changed, 517 insertions(+), 18 deletions(-)
 create mode 100644 libc/src/math/exp10m1f.h
 create mode 100644 libc/src/math/generic/exp10m1f.cpp
 create mode 100644 libc/test/src/math/exhaustive/exp10m1f_test.cpp
 create mode 100644 libc/test/src/math/exp10m1f_test.cpp
 create mode 100644 libc/test/src/math/smoke/exp10m1f_test.cpp

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 6bb53cb76220fc..616739392766f4 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -369,6 +369,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.expf
     libc.src.math.exp10
     libc.src.math.exp10f
+    libc.src.math.exp10m1f
     libc.src.math.exp2
     libc.src.math.exp2f
     libc.src.math.exp2m1f
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index 7a7b6c9c8db5de..ca8fd8e1eeee8e 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -266,7 +266,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | exp10     | |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|         |                        |                      |                        | 7.12.6.4               | F.10.3.4                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 63d0449867114d..65812ccae45d0d 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -548,6 +548,8 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"exp10", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
           FunctionSpec<"exp10f", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
 
+          FunctionSpec<"exp10m1f", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
+
           FunctionSpec<"remainderf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>]>,
           FunctionSpec<"remainder", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
           FunctionSpec<"remainderl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>]>,
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index e8f699fabe3655..45b4dee0eb7291 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -93,6 +93,8 @@ add_math_entrypoint_object(exp2m1f)
 add_math_entrypoint_object(exp10)
 add_math_entrypoint_object(exp10f)
 
+add_math_entrypoint_object(exp10m1f)
+
 add_math_entrypoint_object(expm1)
 add_math_entrypoint_object(expm1f)
 
diff --git a/libc/src/math/exp10m1f.h b/libc/src/math/exp10m1f.h
new file mode 100644
index 00000000000000..e8a242eaba2cbd
--- /dev/null
+++ b/libc/src/math/exp10m1f.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for exp10m1f ----------------------*- 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_EXP10M1F_H
+#define LLVM_LIBC_SRC_MATH_EXP10M1F_H
+
+namespace LIBC_NAMESPACE {
+
+float exp10m1f(float x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_EXP10M1F_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index afbcdea3cf7abb..7b09c93d042fcb 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -887,6 +887,7 @@ add_entrypoint_object(
     .explogxf
     libc.src.errno.errno
     libc.src.__support.common
+    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
@@ -957,6 +958,27 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  exp10m1f
+  SRCS
+    exp10m1f.cpp
+  HDRS
+    ../exp10m1f.h
+  DEPENDS
+    .explogxf
+    libc.src.errno.errno
+    libc.src.__support.common
+    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
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   expm1
   SRCS
diff --git a/libc/src/math/generic/exp10m1f.cpp b/libc/src/math/generic/exp10m1f.cpp
new file mode 100644
index 00000000000000..50d4c50fb869ca
--- /dev/null
+++ b/libc/src/math/generic/exp10m1f.cpp
@@ -0,0 +1,215 @@
+//===-- Implementation of exp10m1f 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/exp10m1f.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/optimization.h"
+#include "src/errno/libc_errno.h"
+
+#include "explogxf.h"
+
+namespace LIBC_NAMESPACE {
+
+static constexpr size_t N_EXCEPTS_LO = 11;
+
+static constexpr fputil::ExceptValues<float, N_EXCEPTS_LO> EXP10M1F_EXCEPTS_LO =
+    {{
+        // x = 0x1.0fe54ep-11, exp10m1f(x) = 0x1.3937eep-10 (RZ)
+        {0x3a07'f2a7U, 0x3a9c'9bf7U, 1U, 0U, 1U},
+        // x = 0x1.80e6eap-11, exp10m1f(x) = 0x1.bb8272p-10 (RZ)
+        {0x3a40'7375U, 0x3add'c139U, 1U, 0U, 1U},
+        // x = -0x1.2a33bcp-51, exp10m1f(x) = -0x1.57515ep-50 (RZ)
+        {0xa615'19deU, 0xa6ab'a8afU, 0U, 1U, 0U},
+        // x = -0x0p+0, exp10m1f(x) = -0x0p+0 (RZ)
+        {0x8000'0000U, 0x8000'0000U, 0U, 0U, 0U},
+        // x = -0x1.b59e08p-31, exp10m1f(x) = -0x1.f7d356p-30 (RZ)
+        {0xb05a'cf04U, 0xb0fb'e9abU, 0U, 1U, 1U},
+        // x = -0x1.bf342p-12, exp10m1f(x) = -0x1.014e02p-10 (RZ)
+        {0xb9df'9a10U, 0xba80'a701U, 0U, 1U, 0U},
+        // x = -0x1.6207fp-11, exp10m1f(x) = -0x1.9746cap-10 (RZ)
+        {0xba31'03f8U, 0xbacb'a365U, 0U, 1U, 1U},
+        // x = -0x1.bd0c66p-11, exp10m1f(x) = -0x1.ffe168p-10 (RZ)
+        {0xba5e'8633U, 0xbaff'f0b4U, 0U, 1U, 1U},
+        // x = -0x1.ffd84cp-10, exp10m1f(x) = -0x1.25faf2p-8 (RZ)
+        {0xbaff'ec26U, 0xbb92'fd79U, 0U, 1U, 0U},
+        // x = -0x1.a74172p-9, exp10m1f(x) = -0x1.e57be2p-8 (RZ)
+        {0xbb53'a0b9U, 0xbbf2'bdf1U, 0U, 1U, 1U},
+        // x = -0x1.cb694cp-9, exp10m1f(x) = -0x1.0764e4p-7 (RZ)
+        {0xbb65'b4a6U, 0xbc03'b272U, 0U, 1U, 0U},
+    }};
+
+static constexpr size_t N_EXCEPTS_HI = 19;
+
+static constexpr fputil::ExceptValues<float, N_EXCEPTS_HI> EXP10M1F_EXCEPTS_HI =
+    {{
+        // (input, RZ output, RU offset, RD offset, RN offset)
+        // x = 0x1.8d31eep-8, exp10m1f(x) = 0x1.cc7e4cp-7 (RZ)
+        {0x3bc6'98f7U, 0x3c66'3f26U, 1U, 0U, 1U},
+        // x = 0x1.915fcep-8, exp10m1f(x) = 0x1.d15f72p-7 (RZ)
+        {0x3bc8'afe7U, 0x3c68'afb9U, 1U, 0U, 0U},
+        // x = 0x1.bcf982p-8, exp10m1f(x) = 0x1.022928p-6 (RZ)
+        {0x3bde'7cc1U, 0x3c81'1494U, 1U, 0U, 1U},
+        // x = 0x1.99ff0ap-7, exp10m1f(x) = 0x1.dee416p-6 (RZ)
+        {0x3c4c'ff85U, 0x3cef'720bU, 1U, 0U, 0U},
+        // x = 0x1.75ea14p-6, exp10m1f(x) = 0x1.b9ff16p-5 (RZ)
+        {0x3cba'f50aU, 0x3d5c'ff8bU, 1U, 0U, 0U},
+        // x = 0x1.f81b64p-6, exp10m1f(x) = 0x1.2cb6bcp-4 (RZ)
+        {0x3cfc'0db2U, 0x3d96'5b5eU, 1U, 0U, 0U},
+        // x = 0x1.fafecp+3, exp10m1f(x) = 0x1.8c880ap+52 (RZ)
+        {0x417d'7f60U, 0x59c6'4405U, 1U, 0U, 0U},
+        // x = -0x1.3bf094p-8, exp10m1f(x) = -0x1.69ba4ap-7 (RZ)
+        {0xbb9d'f84aU, 0xbc34'dd25U, 0U, 1U, 0U},
+        // x = -0x1.4558bcp-8, exp10m1f(x) = -0x1.746fb8p-7 (RZ)
+        {0xbba2'ac5eU, 0xbc3a'37dcU, 0U, 1U, 1U},
+        // x = -0x1.4bb43p-8, exp10m1f(x) = -0x1.7babe4p-7 (RZ)
+        {0xbba5'da18U, 0xbc3d'd5f2U, 0U, 1U, 1U},
+        // x = -0x1.776cc8p-8, exp10m1f(x) = -0x1.ad62c4p-7 (RZ)
+        {0xbbbb'b664U, 0xbc56'b162U, 0U, 1U, 0U},
+        // x = -0x1.f024cp-8, exp10m1f(x) = -0x1.1b20d6p-6 (RZ)
+        {0xbbf8'1260U, 0xbc8d'906bU, 0U, 1U, 1U},
+        // x = -0x1.f510eep-8, exp10m1f(x) = -0x1.1de9aap-6 (RZ)
+        {0xbbfa'8877U, 0xbc8e'f4d5U, 0U, 1U, 0U},
+        // x = -0x1.0b43c4p-7, exp10m1f(x) = -0x1.30d418p-6 (RZ)
+        {0xbc05'a1e2U, 0xbc98'6a0cU, 0U, 1U, 0U},
+        // x = -0x1.245ee4p-7, exp10m1f(x) = -0x1.4d2b86p-6 (RZ)
+        {0xbc12'2f72U, 0xbca6'95c3U, 0U, 1U, 0U},
+        // x = -0x1.f9f2dap-7, exp10m1f(x) = -0x1.1e2186p-5 (RZ)
+        {0xbc7c'f96dU, 0xbd0f'10c3U, 0U, 1U, 0U},
+        // x = -0x1.08e42p-6, exp10m1f(x) = -0x1.2b5c4p-5 (RZ)
+        {0xbc84'7210U, 0xbd15'ae20U, 0U, 1U, 1U},
+        // x = -0x1.0cdc44p-5, exp10m1f(x) = -0x1.2a2152p-4 (RZ)
+        {0xbd06'6e22U, 0xbd95'10a9U, 0U, 1U, 1U},
+        // x = -0x1.ca4322p-5, exp10m1f(x) = -0x1.ef073p-4 (RZ)
+        {0xbd65'2191U, 0xbdf7'8398U, 0U, 1U, 1U},
+    }};
+
+LLVM_LIBC_FUNCTION(float, exp10m1f, (float x)) {
+  using FPBits = fputil::FPBits<float>;
+  FPBits xbits(x);
+
+  uint32_t x_u = xbits.uintval();
+  uint32_t x_abs = x_u & 0x7fff'ffffU;
+
+  // When x >= log10(2^128), or x is nan
+  if (LIBC_UNLIKELY(xbits.is_pos() && x_u >= 0x421a'209bU)) {
+    if (xbits.is_finite()) {
+      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);
+    }
+
+    // x >= log10(2^128) and 10^x - 1 rounds to +inf, or x is +inf or nan
+    return x + FPBits::inf().get_val();
+  }
+
+  // When |x| <= log10(2) * 2^(-6)
+  if (LIBC_UNLIKELY(x_abs <= 0x3b9a'209bU)) {
+    if (auto r = EXP10M1F_EXCEPTS_LO.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+      return r.value();
+
+    double dx = x;
+    double dx_sq = dx * dx;
+    double c0 = dx * Exp10Base::COEFFS[0];
+    double c1 =
+        fputil::multiply_add(dx, Exp10Base::COEFFS[2], Exp10Base::COEFFS[1]);
+    double c2 =
+        fputil::multiply_add(dx, Exp10Base::COEFFS[4], Exp10Base::COEFFS[3]);
+    // 10^dx - 1 ~ (1 + COEFFS[0] * dx + ... + COEFFS[4] * dx^5) - 1
+    //           = COEFFS[0] * dx + ... + COEFFS[4] * dx^5
+    return static_cast<float>(fputil::polyeval(dx_sq, c0, c1, c2));
+  }
+
+  // When x <= log10(2^-25), or x is nan
+  if (LIBC_UNLIKELY(x <= -0x1.e1a5e2p+2f)) {
+    // exp10m1(-inf) = -1
+    if (xbits.is_inf())
+      return -1.0f;
+    // exp10m1(nan) = nan
+    if (xbits.is_nan())
+      return x;
+
+    int rounding = fputil::quick_get_round();
+    if (rounding == FE_UPWARD || rounding == FE_TOWARDZERO ||
+        (rounding == FE_TONEAREST && x == -0x1.e1a5e2p+2f))
+      return -0x1.ffff'fep-1f; // -1.0f + 0x1.0p-24f
+
+    fputil::set_errno_if_required(ERANGE);
+    fputil::raise_except_if_required(FE_UNDERFLOW);
+    return -1.0f;
+  }
+
+  // Exact outputs when x = 1, 2, ..., 10.
+  // Quick check mask: 0x800f'ffffU = ~(bits of 1.0f | ... | bits of 10.0f)
+  if (LIBC_UNLIKELY((x_u & 0x800f'ffffU) == 0)) {
+    switch (x_u) {
+    case 0x3f800000U: // x = 1.0f
+      return 9.0f;
+    case 0x40000000U: // x = 2.0f
+      return 99.0f;
+    case 0x40400000U: // x = 3.0f
+      return 999.0f;
+    case 0x40800000U: // x = 4.0f
+      return 9'999.0f;
+    case 0x40a00000U: // x = 5.0f
+      return 99'999.0f;
+    case 0x40c00000U: // x = 6.0f
+      return 999'999.0f;
+    case 0x40e00000U: // x = 7.0f
+      return 9'999'999.0f;
+    case 0x41000000U: { // x = 8.0f
+      int rounding = fputil::quick_get_round();
+      if (rounding == FE_UPWARD || rounding == FE_TONEAREST)
+        return 100'000'000.0f;
+      return 99'999'992.0f;
+    }
+    case 0x41100000U: { // x = 9.0f
+      int rounding = fputil::quick_get_round();
+      if (rounding == FE_UPWARD || rounding == FE_TONEAREST)
+        return 1'000'000'000.0f;
+      return 999'999'936.0f;
+    }
+    case 0x41200000U: { // x = 10.0f
+      int rounding = fputil::quick_get_round();
+      if (rounding == FE_UPWARD || rounding == FE_TONEAREST)
+        return 10'000'000'000.0f;
+      return 9'999'998'976.0f;
+    }
+    }
+  }
+
+  if (auto r = EXP10M1F_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+    return r.value();
+
+  // Range reduction: 10^x = 2^(mid + hi) * 10^lo
+  //   rr = (2^(mid + hi), lo)
+  auto rr = exp_b_range_reduc<Exp10Base>(x);
+
+  // The low part is approximated by a degree-5 minimax polynomial.
+  // 10^lo ~ 1 + COEFFS[0] * lo + ... + COEFFS[4] * lo^5
+  double lo_sq = rr.lo * rr.lo;
+  double c0 = fputil::multiply_add(rr.lo, Exp10Base::COEFFS[0], 1.0);
+  double c1 =
+      fputil::multiply_add(rr.lo, Exp10Base::COEFFS[2], Exp10Base::COEFFS[1]);
+  double c2 =
+      fputil::multiply_add(rr.lo, Exp10Base::COEFFS[4], Exp10Base::COEFFS[3]);
+  double exp10_lo = fputil::polyeval(lo_sq, c0, c1, c2);
+  // 10^x - 1 = 2^(mid + hi) * 10^lo - 1
+  //          ~ mh * exp10_lo - 1
+  return static_cast<float>(fputil::multiply_add(exp10_lo, rr.mh, -1.0));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 01416eefc15ef8..ff5f3631ee7d7f 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -653,6 +653,7 @@ add_fp_unittest(
   SRCS
     exp2m1f_test.cpp
   DEPENDS
+    libc.hdr.math_macros
     libc.src.errno.errno
     libc.src.math.exp2m1f
     libc.src.__support.CPP.array
@@ -685,6 +686,21 @@ add_fp_unittest(
    libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  exp10m1f_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    exp10m1f_test.cpp
+  DEPENDS
+    libc.hdr.math_macros
+    libc.src.errno.errno
+    libc.src.math.exp10m1f
+    libc.src.__support.CPP.array
+    libc.src.__support.FPUtil.fp_bits
+)
+
 add_fp_unittest(
   copysign_test
   SUITE
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
index 938e519aff0847..8f0c0d4bc66f3d 100644
--- a/libc/test/src/math/exhaustive/CMakeLists.txt
+++ b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -165,6 +165,21 @@ add_fp_unittest(
     -lpthread
 )
 
+add_fp_unittest(
+  exp10m1f_test
+  NO_RUN_POSTBUILD
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    exp10m1f_test.cpp
+  DEPENDS
+    .exhaustive_test
+    libc.src.math.exp10m1f
+  LINK_LIBRARIES
+    -lpthread
+)
+
 add_fp_unittest(
   expm1f_test
   NO_RUN_POSTBUILD
diff --git a/libc/test/src/math/exhaustive/exp10m1f_test.cpp b/libc/test/src/math/exhaustive/exp10m1f_test.cpp
new file mode 100644
index 00000000000000..b9b2290f8b570d
--- /dev/null
+++ b/libc/test/src/math/exhaustive/exp10m1f_test.cpp
@@ -0,0 +1,33 @@
+//===-- Exhaustive test for exp10m1f --------------------------------------===//
+//
+// 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 "exhaustive_test.h"
+#include "src/math/exp10m1f.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+using LlvmLibcExp10m1fExhaustiveTest =
+    LlvmLibcUnaryOpExhaustiveMathTest<float, mpfr::Operation::Exp10m1,
+                                      LIBC_NAMESPACE::exp10m1f>;
+
+// Range: [0, Inf];
+static constexpr uint32_t POS_START = 0x0000'0000U;
+static constexpr uint32_t POS_STOP = 0x7f80'0000U;
+
+TEST_F(LlvmLibcExp10m1fExhaustiveTest, PostiveRange) {
+  test_full_range_all_roundings(POS_START, POS_STOP);
+}
+
+// Range: [-Inf, 0];
+static constexpr uint32_t NEG_START = 0x8000'0000U;
+static constexpr uint32_t NEG_STOP = 0xff80'0000U;
+
+TEST_F(LlvmLibcExp10m1fExhaustiveTest, NegativeRange) {
+  test_full_range_all_roundings(NEG_START, NEG_STOP);
+}
diff --git a/libc/test/src/math/exp10m1f_test.cpp b/libc/test/src/math/exp10m1f_test.cpp
new file mode 100644
index 00000000000000..946b7b4db9280c
--- /dev/null
+++ b/libc/test/src/math/exp10m1f_test.cpp
@@ -0,0 +1,85 @@
+//===-- Unittests for exp10m1f --------------------------------------------===//
+//
+// 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/math_macros.h"
+#include "src/__support/CPP/array.h"
+#include "src/errno/libc_errno.h"
+#include "src/math/exp10m1f.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+#include <stdint.h>
+
+using LlvmLibcExp10m1fTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+TEST_F(LlvmLibcExp10m1fTest, TrickyInputs) {
+  constexpr LIBC_NAMESPACE::cpp::array<float, 30> INPUTS = {
+      // EXP10M1F_EXCEPTS_LO
+      0x1.0fe54ep-11f,
+      0x1.80e6eap-11f,
+      -0x1.2a33bcp-51f,
+      -0x0p+0f,
+      -0x1.b59e08p-31f,
+      -0x1.bf342p-12f,
+      -0x1.6207fp-11f,
+      -0x1.bd0c66p-11f,
+      -0x1.ffd84cp-10f,
+      -0x1.a74172p-9f,
+      -0x1.cb694cp-9f,
+      // EXP10M1F_EXCEPTS_HI
+      0x1.8d31eep-8f,
+      0x1.915fcep-8f,
+      0x1.bcf982p-8f,
+      0x1.99ff0ap-7f,
+      0x1.75ea14p-6f,
+      0x1.f81b64p-6f,
+      0x1.fafecp+3f,
+      -0x1.3bf094p-8f,
+      -0x1.4558bcp-8f,
+      -0x1.4bb43p-8f,
+      -0x1.776cc8p-8f,
+      -0x1.f024cp-8f,
+      -0x1.f510eep-8f,
+      -0x1.0b43c4p-7f,
+      -0x1.245ee4p-7f,
+      -0x1.f9f2dap-7f,
+      -0x1.08e42p-6f,
+      -0x1.0cdc44p-5f,
+      -0x1.ca4322p-5f,
+  };
+
+  for (float x : INPUTS) {
+    LIBC_NAMESPACE::libc_errno = 0;
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp10m1, x,
+                                   LIBC_NAMESPACE::exp10m1f(x), 0.5);
+  }
+}
+
+TEST_F(LlvmLibcExp10m1fTest, InFloatRange) {
+  constexpr uint32_t COUNT = 100'000;
+  constexpr uint32_t STEP = UINT32_MAX / COUNT;
+  for (uint32_t i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+    float x = FPBits(v).get_val();
+    if (isnan(x) || isinf(x))
+      continue;
+    LIBC_NAMESPACE::libc_errno = 0;
+    float result = LIBC_NAMESPACE::exp10m1f(x);
+
+    // If the computation resulted in an error or did not produce valid result
+    // in the single-precision floating point range, then ignore comparing with
+    // MPFR result as MPFR can still produce valid results because of its
+    // wider precision.
+    if (isnan(result) || isinf(result) || LIBC_NAMESPACE::libc_errno != 0)
+      continue;
+    ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp10m1, x,
+                                   LIBC_NAMESPACE::exp10m1f(x), 0.5);
+  }
+}
diff --git a/libc/test/src/math/exp2m1f_test.cpp b/libc/test/src/math/exp2m1f_test.cpp
index cb948289b6179c..46031b546c37aa 100644
--- a/libc/test/src/math/exp2m1f_test.cpp
+++ b/libc/test/src/math/exp2m1f_test.cpp
@@ -8,7 +8,6 @@
 
 #include "hdr/math_macros.h"
 #include "src/__support/CPP/array.h"
-#include "src/__support/FPUtil/FPBits.h"
 #include "src/errno/libc_errno.h"
 #include "src/math/exp2m1f.h"
 #include "test/UnitTest/FPMatcher.h"
@@ -24,17 +23,17 @@ namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
 TEST_F(LlvmLibcExp2m1fTest, TrickyInputs) {
   constexpr LIBC_NAMESPACE::cpp::array<float, 10> INPUTS = {
       // EXP2M1F_EXCEPTS_LO
-      0x1.36dc8ep-36,
-      0x1.224936p-19,
-      0x1.d16d2p-20,
-      0x1.17949ep-14,
-      -0x1.9c3e1ep-38,
-      -0x1.4d89b4p-32,
-      -0x1.a6eac4p-10,
-      -0x1.e7526ep-6,
+      0x1.36dc8ep-36f,
+      0x1.224936p-19f,
+      0x1.d16d2p-20f,
+      0x1.17949ep-14f,
+      -0x1.9c3e1ep-38f,
+      -0x1.4d89b4p-32f,
+      -0x1.a6eac4p-10f,
+      -0x1.e7526ep-6f,
       // EXP2M1F_EXCEPTS_HI
-      0x1.16a972p-1,
-      -0x1.9f12acp-5,
+      0x1.16a972p-1f,
+      -0x1.9f12acp-5f,
   };
 
   for (float x : INPUTS) {
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 22c59c97f6c7fd..70efe6f27b70cc 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -812,6 +812,17 @@ add_fp_unittest(
    libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  exp10m1f_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    exp10m1f_test.cpp
+  DEPENDS
+    libc.src.errno.errno
+    libc.src.math.exp10m1f
+)
+
 add_fp_unittest(
   copysign_test
   SUITE
diff --git a/libc/test/src/math/smoke/exp10m1f_test.cpp b/libc/test/src/math/smoke/exp10m1f_test.cpp
new file mode 100644
index 00000000000000..36957af14bb2fa
--- /dev/null
+++ b/libc/test/src/math/smoke/exp10m1f_test.cpp
@@ -0,0 +1,56 @@
+//===-- Unittests for exp10m1f --------------------------------------------===//
+//
+// 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/exp10m1f.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcExp10m1fTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+TEST_F(LlvmLibcExp10m1fTest, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::exp10m1f(aNaN));
+  EXPECT_FP_EQ_ALL_ROUNDING(inf, LIBC_NAMESPACE::exp10m1f(inf));
+  EXPECT_FP_EQ_ALL_ROUNDING(-1.0f, LIBC_NAMESPACE::exp10m1f(neg_inf));
+  EXPECT_FP_EQ_ALL_ROUNDING(0.0f, LIBC_NAMESPACE::exp10m1f(0.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(-0.0f, LIBC_NAMESPACE::exp10m1f(-0.0f));
+
+  EXPECT_FP_EQ_ALL_ROUNDING(9.0f, LIBC_NAMESPACE::exp10m1f(1.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(99.0f, LIBC_NAMESPACE::exp10m1f(2.0f));
+  EXPECT_FP_EQ_ALL_ROUNDING(999.0f, LIBC_NAMESPACE::exp10m1f(3.0f));
+}
+
+TEST_F(LlvmLibcExp10m1fTest, Overflow) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp10m1f(0x1.fffffep+127f),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp10m1f(128.0f),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp10m1f(0x1.000002p+7f),
+                              FE_OVERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+}
+
+TEST_F(LlvmLibcExp10m1fTest, Underflow) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(
+      -1.0f, LIBC_NAMESPACE::exp10m1f(-0x1.fffffep+127f), FE_UNDERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp10m1f(-0x1.e1a5e4p+2f),
+                              FE_UNDERFLOW);
+  EXPECT_MATH_ERRNO(ERANGE);
+}
diff --git a/libc/test/src/math/smoke/exp2m1f_test.cpp b/libc/test/src/math/smoke/exp2m1f_test.cpp
index 2df43538524728..c27c24e9be7838 100644
--- a/libc/test/src/math/smoke/exp2m1f_test.cpp
+++ b/libc/test/src/math/smoke/exp2m1f_test.cpp
@@ -12,8 +12,6 @@
 #include "test/UnitTest/Test.h"
 
 using LlvmLibcExp2m1fTest = LIBC_NAMESPACE::testing::FPTest<float>;
-using LIBC_NAMESPACE::fputil::testing::ForceRoundingMode;
-using LIBC_NAMESPACE::fputil::testing::RoundingMode;
 
 TEST_F(LlvmLibcExp2m1fTest, SpecialNumbers) {
   LIBC_NAMESPACE::libc_errno = 0;
@@ -33,7 +31,7 @@ TEST_F(LlvmLibcExp2m1fTest, SpecialNumbers) {
 TEST_F(LlvmLibcExp2m1fTest, Overflow) {
   LIBC_NAMESPACE::libc_errno = 0;
 
-  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.fffffep+127),
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.fffffep+127f),
                               FE_OVERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 
@@ -41,7 +39,7 @@ TEST_F(LlvmLibcExp2m1fTest, Overflow) {
                               FE_OVERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 
-  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.000002p+7),
+  EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2m1f(0x1.000002p+7f),
                               FE_OVERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 }
@@ -49,7 +47,7 @@ TEST_F(LlvmLibcExp2m1fTest, Overflow) {
 TEST_F(LlvmLibcExp2m1fTest, Underflow) {
   LIBC_NAMESPACE::libc_errno = 0;
 
-  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.fffffep+127),
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.fffffep+127f),
                               FE_UNDERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 
@@ -57,7 +55,7 @@ TEST_F(LlvmLibcExp2m1fTest, Underflow) {
                               FE_UNDERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 
-  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.900002p4),
+  EXPECT_FP_EQ_WITH_EXCEPTION(-1.0f, LIBC_NAMESPACE::exp2m1f(-0x1.900002p+4f),
                               FE_UNDERFLOW);
   EXPECT_MATH_ERRNO(ERANGE);
 }
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 91a623ddfa12c8..d1274dedaa5b98 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -275,6 +275,29 @@ class MPFRNumber {
     return result;
   }
 
+  MPFRNumber exp10m1() const {
+    // TODO: Only use mpfr_exp10m1 once CI and buildbots get MPFR >= 4.2.0.
+#if MPFR_VERSION_MAJOR > 4 ||                                                  \
+    (MPFR_VERSION_MAJOR == 4 && MPFR_VERSION_MINOR >= 2)
+    MPFRNumber result(*this);
+    mpfr_exp10m1(result.value, value, mpfr_rounding);
+    return result;
+#else
+    unsigned int prec = mpfr_precision * 3;
+    MPFRNumber result(*this, prec);
+
+    MPFRNumber ln10(10.0f, prec);
+    // log(10)
+    mpfr_log(ln10.value, ln10.value, mpfr_rounding);
+    // x * log(10)
+    mpfr_mul(result.value, value, ln10.value, mpfr_rounding);
+    // e^(x * log(10)) - 1
+    int ex = mpfr_expm1(result.value, result.value, mpfr_rounding);
+    mpfr_subnormalize(result.value, ex, mpfr_rounding);
+    return result;
+#endif
+  }
+
   MPFRNumber expm1() const {
     MPFRNumber result(*this);
     mpfr_expm1(result.value, value, mpfr_rounding);
@@ -624,6 +647,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.exp2m1();
   case Operation::Exp10:
     return mpfrInput.exp10();
+  case Operation::Exp10m1:
+    return mpfrInput.exp10m1();
   case Operation::Expm1:
     return mpfrInput.expm1();
   case Operation::Floor:
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h
index d2f73e2628e164..ee208bb72dff38 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.h
+++ b/libc/utils/MPFRWrapper/MPFRUtils.h
@@ -39,6 +39,7 @@ enum class Operation : int {
   Exp2,
   Exp2m1,
   Exp10,
+  Exp10m1,
   Expm1,
   Floor,
   Log,



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