[libc-commits] [libc] [llvm] [libc][math] Refactor exp10m1f implementation to header-only in src/__support/math folder. (PR #159897)
Muhammad Bassiouni via libc-commits
libc-commits at lists.llvm.org
Sat Sep 20 14:03:33 PDT 2025
https://github.com/bassiounix updated https://github.com/llvm/llvm-project/pull/159897
>From df8ad79a406f31aacb1fbf820c815742c17825e7 Mon Sep 17 00:00:00 2001
From: bassiounix <muhammad.m.bassiouni at gmail.com>
Date: Sat, 20 Sep 2025 07:15:51 +0300
Subject: [PATCH] [libc][math] Refactor exp10m1f implementation to header-only
in src/__support/math folder.
---
libc/shared/math.h | 1 +
libc/shared/math/exp10m1f.h | 23 ++
libc/src/__support/math/CMakeLists.txt | 17 ++
libc/src/__support/math/exp10m1f.h | 234 ++++++++++++++++++
libc/src/math/generic/CMakeLists.txt | 11 +-
libc/src/math/generic/exp10m1f.cpp | 209 +---------------
libc/test/shared/CMakeLists.txt | 1 +
libc/test/shared/shared_math_test.cpp | 1 +
.../llvm-project-overlay/libc/BUILD.bazel | 18 +-
9 files changed, 297 insertions(+), 218 deletions(-)
create mode 100644 libc/shared/math/exp10m1f.h
create mode 100644 libc/src/__support/math/exp10m1f.h
diff --git a/libc/shared/math.h b/libc/shared/math.h
index 9ba898ea6dac9..cccd6a375930e 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -45,6 +45,7 @@
#include "math/exp10.h"
#include "math/exp10f.h"
#include "math/exp10f16.h"
+#include "math/exp10m1f.h"
#include "math/expf.h"
#include "math/expf16.h"
#include "math/frexpf.h"
diff --git a/libc/shared/math/exp10m1f.h b/libc/shared/math/exp10m1f.h
new file mode 100644
index 0000000000000..9093705ce801b
--- /dev/null
+++ b/libc/shared/math/exp10m1f.h
@@ -0,0 +1,23 @@
+//===-- Shared exp10m1f function --------------------------------*- 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_EXP10M1F_H
+#define LLVM_LIBC_SHARED_MATH_EXP10M1F_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/exp10m1f.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::exp10m1f;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_EXP10M1F_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 12ffa2ab456e7..84c1b15498672 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -481,6 +481,23 @@ add_header_library(
libc.src.__support.FPUtil.generic.sqrt
)
+add_header_library(
+ exp10m1f
+ HDRS
+ exp10m1f.h
+ DEPENDS
+ .exp10f_utils
+ 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
+)
+
add_header_library(
erff
HDRS
diff --git a/libc/src/__support/math/exp10m1f.h b/libc/src/__support/math/exp10m1f.h
new file mode 100644
index 0000000000000..9fe4ff774ec68
--- /dev/null
+++ b/libc/src/__support/math/exp10m1f.h
@@ -0,0 +1,234 @@
+//===-- 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___SUPPORT_MATH_EXP10M1F_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_EXP10M1F_H
+
+#include "exp10f_utils.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/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace math {
+
+namespace exp10m1f_internal {
+
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+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},
+ }};
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+
+} // namespace exp10m1f_internal
+
+LIBC_INLINE static constexpr float exp10m1f(float x) {
+ using namespace exp10m1f_internal;
+ 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)) {
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+ if (auto r = EXP10M1F_EXCEPTS_LO.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+
+ 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_u >= 0xc0f0d2f1)) {
+ // 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_u == 0xc0f0d2f1))
+ 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;
+ }
+ }
+ }
+
+#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+ if (auto r = EXP10M1F_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
+ return r.value();
+#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
+
+ // 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 math
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_EXP10M1F_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 0830c7a72a6ec..a5d8dfc12d74c 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -1593,16 +1593,7 @@ add_entrypoint_object(
HDRS
../exp10m1f.h
DEPENDS
- 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
- libc.src.__support.math.exp10f_utils
+ libc.src.__support.math.exp10m1f
)
add_entrypoint_object(
diff --git a/libc/src/math/generic/exp10m1f.cpp b/libc/src/math/generic/exp10m1f.cpp
index 8589e3fb6639d..87980b7753b40 100644
--- a/libc/src/math/generic/exp10m1f.cpp
+++ b/libc/src/math/generic/exp10m1f.cpp
@@ -7,215 +7,10 @@
//===----------------------------------------------------------------------===//
#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/libc_errno.h"
-#include "src/__support/macros/config.h"
-#include "src/__support/macros/optimization.h"
-#include "src/__support/math/exp10f_utils.h"
+#include "src/__support/math/exp10m1f.h"
namespace LIBC_NAMESPACE_DECL {
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-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},
- }};
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
-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)) {
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
- if (auto r = EXP10M1F_EXCEPTS_LO.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
- return r.value();
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
- 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_u >= 0xc0f0d2f1)) {
- // 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_u == 0xc0f0d2f1))
- 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;
- }
- }
- }
-
-#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
- if (auto r = EXP10M1F_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value()))
- return r.value();
-#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
-
- // 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));
-}
+LLVM_LIBC_FUNCTION(float, exp10m1f, (float x)) { return math::exp10m1f(x); }
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 9f3e9838d6b78..13a0aae5d4c67 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -36,6 +36,7 @@ add_fp_unittest(
libc.src.__support.math.cospif
libc.src.__support.math.cospif16
libc.src.__support.math.dsqrtl
+ libc.src.__support.math.exp10m1f
libc.src.__support.math.erff
libc.src.__support.math.exp
libc.src.__support.math.exp10
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index 655e7fb48230e..25bf5ad8ae411 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -57,6 +57,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat) {
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::cosf(0.0f));
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::coshf(0.0f));
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::cospif(0.0f));
+ EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::exp10m1f(0.0f));
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::erff(0.0f));
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::exp10f(0.0f));
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::expf(0.0f));
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 9d02ff9f459ae..8d9e80393bf20 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -2657,6 +2657,22 @@ libc_support_library(
],
)
+libc_support_library(
+ name = "__support_math_exp10m1f",
+ hdrs = ["src/__support/math/exp10m1f.h"],
+ deps = [
+ ":__support_fputil_except_value_utils",
+ ":__support_fputil_fenv_impl",
+ ":__support_fputil_fp_bits",
+ ":__support_fputil_multiply_add",
+ ":__support_fputil_polyeval",
+ ":__support_fputil_rounding_mode",
+ ":__support_macros_optimization",
+ ":__support_math_exp10f_utils",
+ ":errno",
+ ],
+)
+
libc_support_library(
name = "__support_math_erff",
hdrs = ["src/__support/math/erff.h"],
@@ -3613,7 +3629,7 @@ libc_math_function(
libc_math_function(
name = "exp10m1f",
additional_deps = [
- ":__support_math_exp10f_utils",
+ ":__support_math_exp10m1f",
],
)
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