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[libc][math] Refactor cbrtf implementation to header-only in src/__support/math folder.
1 parent 09bf2c5 commit 50a8445

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9 files changed

+214
-151
lines changed

9 files changed

+214
-151
lines changed

‎libc/shared/math.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,7 @@
3131
#include "math/atanhf.h"
3232
#include "math/atanhf16.h"
3333
#include "math/cbrt.h"
34+
#include "math/cbrtf.h"
3435
#include "math/erff.h"
3536
#include "math/exp.h"
3637
#include "math/exp10.h"

‎libc/shared/math/cbrtf.h

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@@ -0,0 +1,23 @@
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//===-- Shared cbrtf function -----------------------------------*- C++ -*-===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#ifndef LIBC_SHARED_MATH_CBRTF_H
10+
#define LIBC_SHARED_MATH_CBRTF_H
11+
12+
#include "shared/libc_common.h"
13+
#include "src/__support/math/cbrtf.h"
14+
15+
namespace LIBC_NAMESPACE_DECL {
16+
namespace shared {
17+
18+
using math::cbrtf;
19+
20+
} // namespace shared
21+
} // namespace LIBC_NAMESPACE_DECL
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23+
#endif // LIBC_SHARED_MATH_CBRTF_H

‎libc/src/__support/math/CMakeLists.txt

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -346,6 +346,17 @@ add_header_library(
346346
libc.src.__support.integer_literals
347347
)
348348

349+
add_header_library(
350+
cbrtf
351+
HDRS
352+
cbrtf.h
353+
DEPENDS
354+
libc.src.__support.FPUtil.fenv_impl
355+
libc.src.__support.FPUtil.fp_bits
356+
libc.src.__support.FPUtil.multiply_add
357+
libc.src.__support.macros.optimization
358+
)
359+
349360
add_header_library(
350361
erff
351362
HDRS

‎libc/src/__support/math/cbrtf.h

Lines changed: 161 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,161 @@
1+
//===-- Implementation header for cbrtf -------------------------*- C++ -*-===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#ifndef LIBC_SRC___SUPPORT_MATH_CBRTF_H
10+
#define LIBC_SRC___SUPPORT_MATH_CBRTF_H
11+
12+
#include "src/__support/FPUtil/FEnvImpl.h"
13+
#include "src/__support/FPUtil/FPBits.h"
14+
#include "src/__support/FPUtil/multiply_add.h"
15+
#include "src/__support/macros/config.h"
16+
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
17+
18+
namespace LIBC_NAMESPACE_DECL {
19+
20+
namespace math {
21+
22+
LIBC_INLINE static constexpr float cbrtf(float x) {
23+
// Look up table for 2^(i/3) for i = 0, 1, 2.
24+
constexpr double CBRT2[3] = {1.0, 0x1.428a2f98d728bp0, 0x1.965fea53d6e3dp0};
25+
26+
// Degree-7 polynomials approximation of ((1 + x)^(1/3) - 1)/x for 0 <= x <= 1
27+
// generated by Sollya with:
28+
// > for i from 0 to 15 do {
29+
// P = fpminimax(((1 + x)^(1/3) - 1)/x, 6, [|D...|], [i/16, (i + 1)/16]);
30+
// print("{", coeff(P, 0), ",", coeff(P, 1), ",", coeff(P, 2), ",",
31+
// coeff(P, 3), ",", coeff(P, 4), ",", coeff(P, 5), ",",
32+
// coeff(P, 6), "},");
33+
// };
34+
// Then (1 + x)^(1/3) ~ 1 + x * P(x).
35+
constexpr double COEFFS[16][7] = {
36+
{0x1.55555555554ebp-2, -0x1.c71c71c678c0cp-4, 0x1.f9add2776de81p-5,
37+
-0x1.511e10aa964a7p-5, 0x1.ee44165937fa2p-6, -0x1.7c5c9e059345dp-6,
38+
0x1.047f75e0aff14p-6},
39+
{0x1.5555554d1149ap-2, -0x1.c71c676fcb5bp-4, 0x1.f9ab127dc57ebp-5,
40+
-0x1.50ea8fd1d4c15p-5, 0x1.e9d68f28ced43p-6, -0x1.60e0e1e661311p-6,
41+
0x1.716eca1d6e3bcp-7},
42+
{0x1.5555546377d45p-2, -0x1.c71bc1c6d49d2p-4, 0x1.f9924cc0ed24dp-5,
43+
-0x1.4fea3beb53b3bp-5, 0x1.de028a9a07b1bp-6, -0x1.3b090d2233524p-6,
44+
0x1.0aeca34893785p-7},
45+
{0x1.55554dce9f649p-2, -0x1.c7188b34b98f8p-4, 0x1.f93e1af34af49p-5,
46+
-0x1.4d9a06be75c63p-5, 0x1.cb943f4f68992p-6, -0x1.139a685a5e3c4p-6,
47+
0x1.88410674c6a5dp-8},
48+
{0x1.5555347d211c3p-2, -0x1.c70f2a4b1a5fap-4, 0x1.f88420e8602c3p-5,
49+
-0x1.49becfa4ed3ep-5, 0x1.b475cd9013162p-6, -0x1.dcfee1dd2f8efp-7,
50+
0x1.249bb51a1c498p-8},
51+
{0x1.5554f01b33dbap-2, -0x1.c6facb929dbf1p-4, 0x1.f73fb7861252ep-5,
52+
-0x1.4459a4a0071fap-5, 0x1.9a8df2b504fc2p-6, -0x1.9a7ce3006d06ep-7,
53+
0x1.ba9230918fa2ep-9},
54+
{0x1.55545c695db5fp-2, -0x1.c6d6089f20275p-4, 0x1.f556e0ea80efp-5,
55+
-0x1.3d91372d083f4p-5, 0x1.7f66cff331f4p-6, -0x1.606a562491737p-7,
56+
0x1.52e3e17c71069p-9},
57+
{0x1.55534a879232ap-2, -0x1.c69b836998b84p-4, 0x1.f2bb26dac0e4cp-5,
58+
-0x1.359eed43716d7p-5, 0x1.64218cd824fbcp-6, -0x1.2e703e2e091e8p-7,
59+
0x1.0677d9af6aad4p-9},
60+
{0x1.5551836bb5494p-2, -0x1.c64658c15353bp-4, 0x1.ef68517451a6ep-5,
61+
-0x1.2cc20a980dceep-5, 0x1.49843e0fad93ap-6, -0x1.03c59ccb68e54p-7,
62+
0x1.9ad325dc7adcbp-10},
63+
{0x1.554ecacb0d035p-2, -0x1.c5d2664026ffcp-4, 0x1.eb624796ba809p-5,
64+
-0x1.233803d19a535p-5, 0x1.300decb1c3c28p-6, -0x1.befe18031ec3dp-8,
65+
0x1.449f5ee175c69p-10},
66+
{0x1.554ae1f5ae815p-2, -0x1.c53c6b14ff6b2p-4, 0x1.e6b2d5127bb5bp-5,
67+
-0x1.19387336788a3p-5, 0x1.180955a6ab255p-6, -0x1.81696703ba369p-8,
68+
0x1.02cb36389bd79p-10},
69+
{0x1.55458a59f356ep-2, -0x1.c4820dd631ae9p-4, 0x1.e167af818bd15p-5,
70+
-0x1.0ef35f6f72e52p-5, 0x1.019c33b65e4ebp-6, -0x1.4d25bdd52d3a5p-8,
71+
0x1.a008ae91f5936p-11},
72+
{0x1.553e878eafee1p-2, -0x1.c3a1d0b2a3db2p-4, 0x1.db90d8ed9f89bp-5,
73+
-0x1.0490e20f1ae91p-5, 0x1.d9a5d1fc42fe3p-7, -0x1.20bf8227c2abfp-8,
74+
0x1.50f8174cdb6e9p-11},
75+
{0x1.5535a0dedf1b1p-2, -0x1.c29afb8bd01a1p-4, 0x1.d53f6371c1e27p-5,
76+
-0x1.f463209b433e2p-6, 0x1.b35222a17e44p-7, -0x1.f5efbf505e133p-9,
77+
0x1.12e0e94e8586dp-11},
78+
{0x1.552aa25e57bfdp-2, -0x1.c16d811e4acadp-4, 0x1.ce8489b47aa51p-5,
79+
-0x1.dfde7ff758ea8p-6, 0x1.901f43aac38c8p-7, -0x1.b581d07df5ad5p-9,
80+
0x1.c3726535f1fc6p-12},
81+
{0x1.551d5d9b204d3p-2, -0x1.c019e328f8db1p-4, 0x1.c7710f44fc3cep-5,
82+
-0x1.cbbbe25ea8ba4p-6, 0x1.6fe270088623dp-7, -0x1.7e6fc79733761p-9,
83+
0x1.75077abf18d84p-12},
84+
};
85+
86+
using FloatBits = typename fputil::FPBits<float>;
87+
using DoubleBits = typename fputil::FPBits<double>;
88+
89+
FloatBits x_bits(x);
90+
91+
uint32_t x_abs = x_bits.uintval() & 0x7fff'ffff;
92+
uint32_t sign_bit = (x_bits.uintval() >> 31) << DoubleBits::EXP_LEN;
93+
94+
if (LIBC_UNLIKELY(x == 0.0f || x_abs >= 0x7f80'0000)) {
95+
// x is 0, Inf, or NaN.
96+
// Make sure it works for FTZ/DAZ modes.
97+
return x + x;
98+
}
99+
100+
double xd = static_cast<double>(x);
101+
DoubleBits xd_bits(xd);
102+
103+
// When using biased exponent of x in double precision,
104+
// x_e = real_exponent_of_x + 1023
105+
// Then:
106+
// x_e / 3 = real_exponent_of_x / 3 + 1023/3
107+
// = real_exponent_of_x / 3 + 341
108+
// So to make it the correct biased exponent of x^(1/3), we add
109+
// 1023 - 341 = 682
110+
// to the quotient x_e / 3.
111+
unsigned x_e = static_cast<unsigned>(xd_bits.get_biased_exponent());
112+
unsigned out_e = (x_e / 3 + 682) | sign_bit;
113+
unsigned shift_e = x_e % 3;
114+
115+
// Set x_m = 2^(x_e % 3) * (1.mantissa)
116+
uint64_t x_m = xd_bits.get_mantissa();
117+
// Use the leading 4 bits for look up table
118+
unsigned idx = static_cast<unsigned>(x_m >> (DoubleBits::FRACTION_LEN - 4));
119+
120+
x_m |= static_cast<uint64_t>(DoubleBits::EXP_BIAS)
121+
<< DoubleBits::FRACTION_LEN;
122+
123+
double x_reduced = DoubleBits(x_m).get_val();
124+
double dx = x_reduced - 1.0;
125+
126+
double dx_sq = dx * dx;
127+
double c0 = fputil::multiply_add(dx, COEFFS[idx][0], 1.0);
128+
double c1 = fputil::multiply_add(dx, COEFFS[idx][2], COEFFS[idx][1]);
129+
double c2 = fputil::multiply_add(dx, COEFFS[idx][4], COEFFS[idx][3]);
130+
double c3 = fputil::multiply_add(dx, COEFFS[idx][6], COEFFS[idx][5]);
131+
132+
double dx_4 = dx_sq * dx_sq;
133+
double p0 = fputil::multiply_add(dx_sq, c1, c0);
134+
double p1 = fputil::multiply_add(dx_sq, c3, c2);
135+
136+
double r = fputil::multiply_add(dx_4, p1, p0) * CBRT2[shift_e];
137+
138+
uint64_t r_m = DoubleBits(r).get_mantissa();
139+
// Check if the output is exact. To be exact, the smallest 1-bit of the
140+
// output has to be at least 2^-7 or higher. So we check the lowest 44 bits
141+
// to see if they are within 2^(-52 + 3) errors from all zeros, then the
142+
// result cube root is exact.
143+
if (LIBC_UNLIKELY(((r_m + 8) & 0xfffffffffff) <= 16)) {
144+
if ((r_m & 0xfffffffffff) <= 8)
145+
r_m &= 0xffff'ffff'ffff'ffe0;
146+
else
147+
r_m = (r_m & 0xffff'ffff'ffff'ffe0) + 0x20;
148+
fputil::clear_except_if_required(FE_INEXACT);
149+
}
150+
// Adjust exponent and sign.
151+
uint64_t r_bits =
152+
r_m | (static_cast<uint64_t>(out_e) << DoubleBits::FRACTION_LEN);
153+
154+
return static_cast<float>(DoubleBits(r_bits).get_val());
155+
}
156+
157+
} // namespace math
158+
159+
} // namespace LIBC_NAMESPACE_DECL
160+
161+
#endif // LIBC_SRC___SUPPORT_MATH_CBRTF_H

‎libc/src/math/generic/CMakeLists.txt

Lines changed: 1 addition & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -4819,11 +4819,7 @@ add_entrypoint_object(
48194819
HDRS
48204820
../cbrtf.h
48214821
DEPENDS
4822-
libc.hdr.fenv_macros
4823-
libc.src.__support.FPUtil.fenv_impl
4824-
libc.src.__support.FPUtil.fp_bits
4825-
libc.src.__support.FPUtil.multiply_add
4826-
libc.src.__support.macros.optimization
4822+
libc.src.__support.math.cbrtf
48274823
)
48284824

48294825
add_entrypoint_object(

‎libc/src/math/generic/cbrtf.cpp

Lines changed: 2 additions & 145 deletions
Original file line numberDiff line numberDiff line change
@@ -7,153 +7,10 @@
77
//===----------------------------------------------------------------------===//
88

99
#include "src/math/cbrtf.h"
10-
#include "hdr/fenv_macros.h"
11-
#include "src/__support/FPUtil/FEnvImpl.h"
12-
#include "src/__support/FPUtil/FPBits.h"
13-
#include "src/__support/FPUtil/multiply_add.h"
14-
#include "src/__support/common.h"
15-
#include "src/__support/macros/config.h"
16-
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
10+
#include "src/__support/math/cbrtf.h"
1711

1812
namespace LIBC_NAMESPACE_DECL {
1913

20-
namespace {
21-
22-
// Look up table for 2^(i/3) for i = 0, 1, 2.
23-
constexpr double CBRT2[3] = {1.0, 0x1.428a2f98d728bp0, 0x1.965fea53d6e3dp0};
24-
25-
// Degree-7 polynomials approximation of ((1 + x)^(1/3) - 1)/x for 0 <= x <= 1
26-
// generated by Sollya with:
27-
// > for i from 0 to 15 do {
28-
// P = fpminimax(((1 + x)^(1/3) - 1)/x, 6, [|D...|], [i/16, (i + 1)/16]);
29-
// print("{", coeff(P, 0), ",", coeff(P, 1), ",", coeff(P, 2), ",",
30-
// coeff(P, 3), ",", coeff(P, 4), ",", coeff(P, 5), ",",
31-
// coeff(P, 6), "},");
32-
// };
33-
// Then (1 + x)^(1/3) ~ 1 + x * P(x).
34-
constexpr double COEFFS[16][7] = {
35-
{0x1.55555555554ebp-2, -0x1.c71c71c678c0cp-4, 0x1.f9add2776de81p-5,
36-
-0x1.511e10aa964a7p-5, 0x1.ee44165937fa2p-6, -0x1.7c5c9e059345dp-6,
37-
0x1.047f75e0aff14p-6},
38-
{0x1.5555554d1149ap-2, -0x1.c71c676fcb5bp-4, 0x1.f9ab127dc57ebp-5,
39-
-0x1.50ea8fd1d4c15p-5, 0x1.e9d68f28ced43p-6, -0x1.60e0e1e661311p-6,
40-
0x1.716eca1d6e3bcp-7},
41-
{0x1.5555546377d45p-2, -0x1.c71bc1c6d49d2p-4, 0x1.f9924cc0ed24dp-5,
42-
-0x1.4fea3beb53b3bp-5, 0x1.de028a9a07b1bp-6, -0x1.3b090d2233524p-6,
43-
0x1.0aeca34893785p-7},
44-
{0x1.55554dce9f649p-2, -0x1.c7188b34b98f8p-4, 0x1.f93e1af34af49p-5,
45-
-0x1.4d9a06be75c63p-5, 0x1.cb943f4f68992p-6, -0x1.139a685a5e3c4p-6,
46-
0x1.88410674c6a5dp-8},
47-
{0x1.5555347d211c3p-2, -0x1.c70f2a4b1a5fap-4, 0x1.f88420e8602c3p-5,
48-
-0x1.49becfa4ed3ep-5, 0x1.b475cd9013162p-6, -0x1.dcfee1dd2f8efp-7,
49-
0x1.249bb51a1c498p-8},
50-
{0x1.5554f01b33dbap-2, -0x1.c6facb929dbf1p-4, 0x1.f73fb7861252ep-5,
51-
-0x1.4459a4a0071fap-5, 0x1.9a8df2b504fc2p-6, -0x1.9a7ce3006d06ep-7,
52-
0x1.ba9230918fa2ep-9},
53-
{0x1.55545c695db5fp-2, -0x1.c6d6089f20275p-4, 0x1.f556e0ea80efp-5,
54-
-0x1.3d91372d083f4p-5, 0x1.7f66cff331f4p-6, -0x1.606a562491737p-7,
55-
0x1.52e3e17c71069p-9},
56-
{0x1.55534a879232ap-2, -0x1.c69b836998b84p-4, 0x1.f2bb26dac0e4cp-5,
57-
-0x1.359eed43716d7p-5, 0x1.64218cd824fbcp-6, -0x1.2e703e2e091e8p-7,
58-
0x1.0677d9af6aad4p-9},
59-
{0x1.5551836bb5494p-2, -0x1.c64658c15353bp-4, 0x1.ef68517451a6ep-5,
60-
-0x1.2cc20a980dceep-5, 0x1.49843e0fad93ap-6, -0x1.03c59ccb68e54p-7,
61-
0x1.9ad325dc7adcbp-10},
62-
{0x1.554ecacb0d035p-2, -0x1.c5d2664026ffcp-4, 0x1.eb624796ba809p-5,
63-
-0x1.233803d19a535p-5, 0x1.300decb1c3c28p-6, -0x1.befe18031ec3dp-8,
64-
0x1.449f5ee175c69p-10},
65-
{0x1.554ae1f5ae815p-2, -0x1.c53c6b14ff6b2p-4, 0x1.e6b2d5127bb5bp-5,
66-
-0x1.19387336788a3p-5, 0x1.180955a6ab255p-6, -0x1.81696703ba369p-8,
67-
0x1.02cb36389bd79p-10},
68-
{0x1.55458a59f356ep-2, -0x1.c4820dd631ae9p-4, 0x1.e167af818bd15p-5,
69-
-0x1.0ef35f6f72e52p-5, 0x1.019c33b65e4ebp-6, -0x1.4d25bdd52d3a5p-8,
70-
0x1.a008ae91f5936p-11},
71-
{0x1.553e878eafee1p-2, -0x1.c3a1d0b2a3db2p-4, 0x1.db90d8ed9f89bp-5,
72-
-0x1.0490e20f1ae91p-5, 0x1.d9a5d1fc42fe3p-7, -0x1.20bf8227c2abfp-8,
73-
0x1.50f8174cdb6e9p-11},
74-
{0x1.5535a0dedf1b1p-2, -0x1.c29afb8bd01a1p-4, 0x1.d53f6371c1e27p-5,
75-
-0x1.f463209b433e2p-6, 0x1.b35222a17e44p-7, -0x1.f5efbf505e133p-9,
76-
0x1.12e0e94e8586dp-11},
77-
{0x1.552aa25e57bfdp-2, -0x1.c16d811e4acadp-4, 0x1.ce8489b47aa51p-5,
78-
-0x1.dfde7ff758ea8p-6, 0x1.901f43aac38c8p-7, -0x1.b581d07df5ad5p-9,
79-
0x1.c3726535f1fc6p-12},
80-
{0x1.551d5d9b204d3p-2, -0x1.c019e328f8db1p-4, 0x1.c7710f44fc3cep-5,
81-
-0x1.cbbbe25ea8ba4p-6, 0x1.6fe270088623dp-7, -0x1.7e6fc79733761p-9,
82-
0x1.75077abf18d84p-12},
83-
};
84-
85-
} // anonymous namespace
86-
87-
LLVM_LIBC_FUNCTION(float, cbrtf, (float x)) {
88-
using FloatBits = typename fputil::FPBits<float>;
89-
using DoubleBits = typename fputil::FPBits<double>;
90-
91-
FloatBits x_bits(x);
92-
93-
uint32_t x_abs = x_bits.uintval() & 0x7fff'ffff;
94-
uint32_t sign_bit = (x_bits.uintval() >> 31) << DoubleBits::EXP_LEN;
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96-
if (LIBC_UNLIKELY(x == 0.0f || x_abs >= 0x7f80'0000)) {
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// x is 0, Inf, or NaN.
98-
// Make sure it works for FTZ/DAZ modes.
99-
return x + x;
100-
}
101-
102-
double xd = static_cast<double>(x);
103-
DoubleBits xd_bits(xd);
104-
105-
// When using biased exponent of x in double precision,
106-
// x_e = real_exponent_of_x + 1023
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// Then:
108-
// x_e / 3 = real_exponent_of_x / 3 + 1023/3
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// = real_exponent_of_x / 3 + 341
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// So to make it the correct biased exponent of x^(1/3), we add
111-
// 1023 - 341 = 682
112-
// to the quotient x_e / 3.
113-
unsigned x_e = static_cast<unsigned>(xd_bits.get_biased_exponent());
114-
unsigned out_e = (x_e / 3 + 682) | sign_bit;
115-
unsigned shift_e = x_e % 3;
116-
117-
// Set x_m = 2^(x_e % 3) * (1.mantissa)
118-
uint64_t x_m = xd_bits.get_mantissa();
119-
// Use the leading 4 bits for look up table
120-
unsigned idx = static_cast<unsigned>(x_m >> (DoubleBits::FRACTION_LEN - 4));
121-
122-
x_m |= static_cast<uint64_t>(DoubleBits::EXP_BIAS)
123-
<< DoubleBits::FRACTION_LEN;
124-
125-
double x_reduced = DoubleBits(x_m).get_val();
126-
double dx = x_reduced - 1.0;
127-
128-
double dx_sq = dx * dx;
129-
double c0 = fputil::multiply_add(dx, COEFFS[idx][0], 1.0);
130-
double c1 = fputil::multiply_add(dx, COEFFS[idx][2], COEFFS[idx][1]);
131-
double c2 = fputil::multiply_add(dx, COEFFS[idx][4], COEFFS[idx][3]);
132-
double c3 = fputil::multiply_add(dx, COEFFS[idx][6], COEFFS[idx][5]);
133-
134-
double dx_4 = dx_sq * dx_sq;
135-
double p0 = fputil::multiply_add(dx_sq, c1, c0);
136-
double p1 = fputil::multiply_add(dx_sq, c3, c2);
137-
138-
double r = fputil::multiply_add(dx_4, p1, p0) * CBRT2[shift_e];
139-
140-
uint64_t r_m = DoubleBits(r).get_mantissa();
141-
// Check if the output is exact. To be exact, the smallest 1-bit of the
142-
// output has to be at least 2^-7 or higher. So we check the lowest 44 bits
143-
// to see if they are within 2^(-52 + 3) errors from all zeros, then the
144-
// result cube root is exact.
145-
if (LIBC_UNLIKELY(((r_m + 8) & 0xfffffffffff) <= 16)) {
146-
if ((r_m & 0xfffffffffff) <= 8)
147-
r_m &= 0xffff'ffff'ffff'ffe0;
148-
else
149-
r_m = (r_m & 0xffff'ffff'ffff'ffe0) + 0x20;
150-
fputil::clear_except_if_required(FE_INEXACT);
151-
}
152-
// Adjust exponent and sign.
153-
uint64_t r_bits =
154-
r_m | (static_cast<uint64_t>(out_e) << DoubleBits::FRACTION_LEN);
155-
156-
return static_cast<float>(DoubleBits(r_bits).get_val());
157-
}
14+
LLVM_LIBC_FUNCTION(float, cbrtf, (float x)) { return math::cbrtf(x); }
15815

15916
} // namespace LIBC_NAMESPACE_DECL

‎libc/test/shared/CMakeLists.txt

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -27,6 +27,7 @@ add_fp_unittest(
2727
libc.src.__support.math.atanhf
2828
libc.src.__support.math.atanhf16
2929
libc.src.__support.math.cbrt
30+
libc.src.__support.math.cbrtf
3031
libc.src.__support.math.erff
3132
libc.src.__support.math.exp
3233
libc.src.__support.math.exp10

‎libc/test/shared/shared_math_test.cpp

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -49,6 +49,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat) {
4949
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::atan2f(0.0f, 0.0f));
5050
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::atanf(0.0f));
5151
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::atanhf(0.0f));
52+
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::cbrtf(0.0f));
5253
EXPECT_FP_EQ(0x0p+0f, LIBC_NAMESPACE::shared::erff(0.0f));
5354
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::exp10f(0.0f));
5455
EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::expf(0.0f));

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