-
Notifications
You must be signed in to change notification settings - Fork 11.8k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
[libc][math][c23] Add exp10m1f16 C23 math function
Part of #95250.
- Loading branch information
1 parent
aabdd8f
commit 9cb1171
Showing
16 changed files
with
460 additions
and
45 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.