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[libc][math][c23] Add exp2m1f16 C23 math function #105690
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f8b28f9
[libc][math][c23] Add exp2m1f16 C23 math function
overmighty 52d998d
Enable exp2m1f16 entrypoint on GPUs
overmighty 430b14a
Fix entrypoint name in GPU config
overmighty da6b98a
Update includes and CMake target dependencies
overmighty eca8d05
Migrate to fputil::cast and use implicit casts for constants
overmighty 5de4d1b
Disable exp2m1f16 on GPUs for now
overmighty f3ea05a
Add exp2m1f16 in newhdrgen math.yaml
overmighty 5058e8c
Update CMake target dependencies
overmighty 1f17209
Remove braces from single-statement if in exp2m1f16
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,21 @@ | ||
| //===-- Implementation header for exp2m1f16 ---------------------*- 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 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #ifndef LLVM_LIBC_SRC_MATH_EXP2M1F16_H | ||
| #define LLVM_LIBC_SRC_MATH_EXP2M1F16_H | ||
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| #include "src/__support/macros/config.h" | ||
| #include "src/__support/macros/properties/types.h" | ||
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| namespace LIBC_NAMESPACE_DECL { | ||
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| float16 exp2m1f16(float16 x); | ||
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| } // namespace LIBC_NAMESPACE_DECL | ||
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| #endif // LLVM_LIBC_SRC_MATH_EXP2M1F16_H |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,162 @@ | ||
| //===-- Half-precision 2^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 | ||
| // | ||
| //===----------------------------------------------------------------------===// | ||
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| #include "src/math/exp2m1f16.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/cast.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" | ||
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| namespace LIBC_NAMESPACE_DECL { | ||
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| static constexpr fputil::ExceptValues<float16, 6> EXP2M1F16_EXCEPTS_LO = {{ | ||
| // (input, RZ output, RU offset, RD offset, RN offset) | ||
| // x = 0x1.cf4p-13, exp2m1f16(x) = 0x1.41p-13 (RZ) | ||
| {0x0b3dU, 0x0904U, 1U, 0U, 1U}, | ||
| // x = 0x1.4fcp-12, exp2m1f16(x) = 0x1.d14p-13 (RZ) | ||
| {0x0d3fU, 0x0b45U, 1U, 0U, 1U}, | ||
| // x = 0x1.63p-11, exp2m1f16(x) = 0x1.ec4p-12 (RZ) | ||
| {0x118cU, 0x0fb1U, 1U, 0U, 0U}, | ||
| // x = 0x1.6fp-7, exp2m1f16(x) = 0x1.fe8p-8 (RZ) | ||
| {0x21bcU, 0x1ffaU, 1U, 0U, 1U}, | ||
| // x = -0x1.c6p-10, exp2m1f16(x) = -0x1.3a8p-10 (RZ) | ||
| {0x9718U, 0x94eaU, 0U, 1U, 0U}, | ||
| // x = -0x1.cfcp-10, exp2m1f16(x) = -0x1.414p-10 (RZ) | ||
| {0x973fU, 0x9505U, 0U, 1U, 0U}, | ||
| }}; | ||
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| #ifdef LIBC_TARGET_CPU_HAS_FMA | ||
| static constexpr size_t N_EXP2M1F16_EXCEPTS_HI = 6; | ||
| #else | ||
| static constexpr size_t N_EXP2M1F16_EXCEPTS_HI = 7; | ||
| #endif | ||
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| static constexpr fputil::ExceptValues<float16, N_EXP2M1F16_EXCEPTS_HI> | ||
| EXP2M1F16_EXCEPTS_HI = {{ | ||
| // (input, RZ output, RU offset, RD offset, RN offset) | ||
| // x = 0x1.e58p-3, exp2m1f16(x) = 0x1.6dcp-3 (RZ) | ||
| {0x3396U, 0x31b7U, 1U, 0U, 0U}, | ||
| #ifndef LIBC_TARGET_CPU_HAS_FMA | ||
| // x = 0x1.2e8p-2, exp2m1f16(x) = 0x1.d14p-3 (RZ) | ||
| {0x34baU, 0x3345U, 1U, 0U, 0U}, | ||
| #endif | ||
| // x = 0x1.ad8p-2, exp2m1f16(x) = 0x1.598p-2 (RZ) | ||
| {0x36b6U, 0x3566U, 1U, 0U, 0U}, | ||
| #ifdef LIBC_TARGET_CPU_HAS_FMA | ||
| // x = 0x1.edcp-2, exp2m1f16(x) = 0x1.964p-2 (RZ) | ||
| {0x37b7U, 0x3659U, 1U, 0U, 1U}, | ||
| #endif | ||
| // x = -0x1.804p-3, exp2m1f16(x) = -0x1.f34p-4 (RZ) | ||
| {0xb201U, 0xafcdU, 0U, 1U, 1U}, | ||
| // x = -0x1.f3p-3, exp2m1f16(x) = -0x1.3e4p-3 (RZ) | ||
| {0xb3ccU, 0xb0f9U, 0U, 1U, 0U}, | ||
| // x = -0x1.294p-1, exp2m1f16(x) = -0x1.53p-2 (RZ) | ||
| {0xb8a5U, 0xb54cU, 0U, 1U, 1U}, | ||
| #ifndef LIBC_TARGET_CPU_HAS_FMA | ||
| // x = -0x1.a34p-1, exp2m1f16(x) = -0x1.bb4p-2 (RZ) | ||
| {0xba8dU, 0xb6edU, 0U, 1U, 1U}, | ||
| #endif | ||
| }}; | ||
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| LLVM_LIBC_FUNCTION(float16, exp2m1f16, (float16 x)) { | ||
| using FPBits = fputil::FPBits<float16>; | ||
| FPBits x_bits(x); | ||
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| uint16_t x_u = x_bits.uintval(); | ||
| uint16_t x_abs = x_u & 0x7fffU; | ||
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| // When |x| <= 2^(-3), or |x| >= 11, or x is NaN. | ||
| if (LIBC_UNLIKELY(x_abs <= 0x3000U || x_abs >= 0x4980U)) { | ||
| // exp2m1(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(); | ||
| } | ||
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| return x; | ||
| } | ||
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| // When x >= 16. | ||
| if (x_u >= 0x4c00 && x_bits.is_pos()) { | ||
| // exp2m1(+inf) = +inf | ||
| if (x_bits.is_inf()) | ||
| return FPBits::inf().get_val(); | ||
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| 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(); | ||
| } | ||
| } | ||
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| // When x < -11. | ||
| if (x_u > 0xc980U) { | ||
| // exp2m1(-inf) = -1 | ||
| if (x_bits.is_inf()) | ||
| return FPBits::one(Sign::NEG).get_val(); | ||
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| // When -12 < x < -11, round(2^x - 1, HP, RN) = -0x1.ffcp-1. | ||
| if (x_u < 0xca00U) | ||
| return fputil::round_result_slightly_down( | ||
| fputil::cast<float16>(-0x1.ffcp-1)); | ||
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| // When x <= -12, round(2^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 -0x1.ffcp-1; | ||
| } | ||
| } | ||
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| // When |x| <= 2^(-3). | ||
| if (x_abs <= 0x3000U) { | ||
| if (auto r = EXP2M1F16_EXCEPTS_LO.lookup(x_u); | ||
| LIBC_UNLIKELY(r.has_value())) | ||
| return r.value(); | ||
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| float xf = x; | ||
| // Degree-5 minimax polynomial generated by Sollya with the following | ||
| // commands: | ||
| // > display = hexadecimal; | ||
| // > P = fpminimax((2^x - 1)/x, 4, [|SG...|], [-2^-3, 2^-3]); | ||
| // > x * P; | ||
| return fputil::cast<float16>( | ||
| xf * fputil::polyeval(xf, 0x1.62e43p-1f, 0x1.ebfbdep-3f, | ||
| 0x1.c6af88p-5f, 0x1.3b45d6p-7f, | ||
| 0x1.641e7cp-10f)); | ||
| } | ||
| } | ||
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| if (auto r = EXP2M1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value())) | ||
| return r.value(); | ||
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| // exp2(x) = exp2(hi + mid) * exp2(lo) | ||
| auto [exp2_hi_mid, exp2_lo] = exp2_range_reduction(x); | ||
| // exp2m1(x) = exp2(hi + mid) * exp2(lo) - 1 | ||
| return fputil::cast<float16>( | ||
| fputil::multiply_add(exp2_hi_mid, exp2_lo, -1.0f)); | ||
| } | ||
|
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| } // namespace LIBC_NAMESPACE_DECL |
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