diff mbox series

[13/17] math: Use log2p1f from CORE-MATH

Message ID 20241025182614.2022697-14-adhemerval.zanella@linaro.org
State New
Headers show
Series Add more CORE-MATH on libm | expand

Commit Message

Adhemerval Zanella Netto Oct. 25, 2024, 6:21 p.m. UTC
The CORE-MATH implementation is correctly rounded (for any rounding mode)
and shows better performance compared to the generic log2p1f.

The code was adapted to glibc style and to use the definition of
math_config.h (to handle errno, overflow, and underflow).

Benchtest on x64_64 (Ryzen 9 5900X, gcc 14.2.1), aarch64 (Neoverse-N1,
gcc 13.3.1), and powerpc (POWER10, gcc 13.2.1):

Latency                      master        patched   improvement
x86_64                      70.1462        47.0090        32.98%
x86_64v2                    70.2513        47.6160        32.22%
x86_64v3                    60.4840        39.9443        33.96%
i686                        164.068        122.909        25.09%
aarch64                     25.9169        16.9207        34.71%
power10                     18.1261        9.8592         45.61%
powerpc                     17.2683        9.38665        45.64%

reciprocal-throughput        master        patched   improvement
x86_64                      26.2240        16.4082        37.43%
x86_64v2                    25.0911        15.7480        37.24%
x86_64v3                    20.9371        11.7264        43.99%
i686                        90.4209        95.3073        -5.40%
aarch64                     16.8537        8.9561         46.86%
power10                     12.9401        6.5555         49.34%
powerpc                     9.01763        7.54745        16.30%

The performance decrease for i686 is mostly due the use of x87 fpu,
when building with '-msse2 -mfpmath=sse:

                             master        patched   improvement
latency                     164.068        102.982        37.23%
reciprocal-throughput       89.1968        82.5117         7.49%

Signed-off-by: Alexei Sibidanov <sibid@uvic.ca>
Signed-off-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---
 SHARED-FILES                                  |   4 +
 sysdeps/aarch64/libm-test-ulps                |   4 -
 sysdeps/arc/fpu/libm-test-ulps                |   4 -
 sysdeps/arc/nofpu/libm-test-ulps              |   2 -
 sysdeps/arm/libm-test-ulps                    |   4 -
 sysdeps/hppa/fpu/libm-test-ulps               |   4 -
 sysdeps/i386/fpu/libm-test-ulps               |   4 -
 .../i386/i686/fpu/multiarch/libm-test-ulps    |   4 -
 sysdeps/ieee754/flt-32/s_log2p1f.c            | 248 ++++++++++++++++++
 sysdeps/loongarch/lp64/libm-test-ulps         |   4 -
 sysdeps/m68k/m680x0/fpu/libm-test-ulps        |   4 -
 sysdeps/mips/mips32/libm-test-ulps            |   4 -
 sysdeps/mips/mips64/libm-test-ulps            |   4 -
 sysdeps/powerpc/fpu/libm-test-ulps            |   4 -
 sysdeps/powerpc/nofpu/libm-test-ulps          |   4 -
 sysdeps/riscv/nofpu/libm-test-ulps            |   1 -
 sysdeps/riscv/rvd/libm-test-ulps              |   4 -
 sysdeps/s390/fpu/libm-test-ulps               |   4 -
 sysdeps/sparc/fpu/libm-test-ulps              |   4 -
 sysdeps/x86_64/fpu/libm-test-ulps             |   4 -
 20 files changed, 252 insertions(+), 67 deletions(-)
 create mode 100644 sysdeps/ieee754/flt-32/s_log2p1f.c
diff mbox series

Patch

diff --git a/SHARED-FILES b/SHARED-FILES
index a559e97318..98ad2671b1 100644
--- a/SHARED-FILES
+++ b/SHARED-FILES
@@ -243,3 +243,7 @@  sysdeps/ieee754/flt-32/s_expm1f.c
   (file src/binary32/expm1/expm1f.c in CORE_MATH)
   - The code was adapted to use glibc code style and internal
     functions to handle errno, overflow, and underflow.
+sysdeps/ieee754/flt-32/s_log2p1f.c
+  (file src/binary32/log2p1/log2p1f.c in CORE_MATH)
+  - The code was adapted to use glibc code style and internal
+    functions to handle errno, overflow, and underflow.
diff --git a/sysdeps/aarch64/libm-test-ulps b/sysdeps/aarch64/libm-test-ulps
index c6c40df9fa..cb1c18cb50 100644
--- a/sysdeps/aarch64/libm-test-ulps
+++ b/sysdeps/aarch64/libm-test-ulps
@@ -1422,22 +1422,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_advsimd":
diff --git a/sysdeps/arc/fpu/libm-test-ulps b/sysdeps/arc/fpu/libm-test-ulps
index ca01eb3b4b..d233bd75a0 100644
--- a/sysdeps/arc/fpu/libm-test-ulps
+++ b/sysdeps/arc/fpu/libm-test-ulps
@@ -1012,19 +1012,15 @@  float: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 
 Function: "log_towardzero":
 double: 1
diff --git a/sysdeps/arc/nofpu/libm-test-ulps b/sysdeps/arc/nofpu/libm-test-ulps
index 266381f6ea..fe74fb8ea9 100644
--- a/sysdeps/arc/nofpu/libm-test-ulps
+++ b/sysdeps/arc/nofpu/libm-test-ulps
@@ -246,11 +246,9 @@  float: 1
 
 Function: "log2p1":
 double: 1
-float: 2
 
 Function: "logp1":
 double: 1
-float: 1
 
 Function: "pow":
 double: 1
diff --git a/sysdeps/arm/libm-test-ulps b/sysdeps/arm/libm-test-ulps
index 12451d24a7..b6b194143a 100644
--- a/sysdeps/arm/libm-test-ulps
+++ b/sysdeps/arm/libm-test-ulps
@@ -1006,19 +1006,15 @@  float: 3
 
 Function: "log2p1":
 double: 1
-float: 2
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 
 Function: "log_downward":
 float: 2
diff --git a/sysdeps/hppa/fpu/libm-test-ulps b/sysdeps/hppa/fpu/libm-test-ulps
index 05ad1cf9b3..9f89528947 100644
--- a/sysdeps/hppa/fpu/libm-test-ulps
+++ b/sysdeps/hppa/fpu/libm-test-ulps
@@ -1029,19 +1029,15 @@  float: 3
 
 Function: "log2p1":
 double: 2
-float: 2
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 
 Function: "log_downward":
 float: 2
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index abf9a9192b..d0bd63371d 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -1484,25 +1484,21 @@  ldouble: 1
 
 Function: "log2p1":
 double: 1
-float: 1
 float128: 3
 ldouble: 4
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 float128: 3
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 float128: 2
 ldouble: 3
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 float128: 3
 ldouble: 5
 
diff --git a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
index 6d9d49d153..a97722b7e7 100644
--- a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
+++ b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
@@ -1487,25 +1487,21 @@  ldouble: 1
 
 Function: "log2p1":
 double: 1
-float: 1
 float128: 3
 ldouble: 4
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 float128: 3
 ldouble: 4
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 float128: 2
 ldouble: 4
 
 Function: "log2p1_upward":
 double: 1
-float: 2
 float128: 3
 ldouble: 5
 
diff --git a/sysdeps/ieee754/flt-32/s_log2p1f.c b/sysdeps/ieee754/flt-32/s_log2p1f.c
new file mode 100644
index 0000000000..a185ddc376
--- /dev/null
+++ b/sysdeps/ieee754/flt-32/s_log2p1f.c
@@ -0,0 +1,248 @@ 
+/* Correctly-rounded biased argument natural logarithm function for binary32
+   value.
+
+Copyright (c) 2022-2024 Alexei Sibidanov.
+
+This file is part of the CORE-MATH project
+project (file src/binary32/log2p1/log2p1f.c revision bc385c2).
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#include <errno.h>
+#include <math.h>
+#include <math-underflow.h>
+#include <libm-alias-float.h>
+#include "math_config.h"
+
+float
+__log2p1f (float x)
+{
+  static const double ix[] =
+    {
+      0x1p+0,           0x1.fc07f01fcp-1, 0x1.f81f81f82p-1,
+      0x1.f44659e4ap-1, 0x1.f07c1f07cp-1, 0x1.ecc07b302p-1,
+      0x1.e9131abfp-1,  0x1.e573ac902p-1, 0x1.e1e1e1e1ep-1,
+      0x1.de5d6e3f8p-1, 0x1.dae6076bap-1, 0x1.d77b654b8p-1,
+      0x1.d41d41d42p-1, 0x1.d0cb58f6ep-1, 0x1.cd8568904p-1,
+      0x1.ca4b3055ep-1, 0x1.c71c71c72p-1, 0x1.c3f8f01c4p-1,
+      0x1.c0e070382p-1, 0x1.bdd2b8994p-1, 0x1.bacf914c2p-1,
+      0x1.b7d6c3ddap-1, 0x1.b4e81b4e8p-1, 0x1.b2036406cp-1,
+      0x1.af286bca2p-1, 0x1.ac5701ac6p-1, 0x1.a98ef606ap-1,
+      0x1.a6d01a6dp-1,  0x1.a41a41a42p-1, 0x1.a16d3f97ap-1,
+      0x1.9ec8e951p-1,  0x1.9c2d14ee4p-1, 0x1.99999999ap-1,
+      0x1.970e4f80cp-1, 0x1.948b0fcd6p-1, 0x1.920fb49dp-1,
+      0x1.8f9c18f9cp-1, 0x1.8d3018d3p-1,  0x1.8acb90f6cp-1,
+      0x1.886e5f0acp-1, 0x1.861861862p-1, 0x1.83c977ab2p-1,
+      0x1.818181818p-1, 0x1.7f405fd02p-1, 0x1.7d05f417ep-1,
+      0x1.7ad2208ep-1,  0x1.78a4c8178p-1, 0x1.767dce434p-1,
+      0x1.745d1745ep-1, 0x1.724287f46p-1, 0x1.702e05c0cp-1,
+      0x1.6e1f76b44p-1, 0x1.6c16c16c2p-1, 0x1.6a13cd154p-1,
+      0x1.681681682p-1, 0x1.661ec6a52p-1, 0x1.642c8590cp-1,
+      0x1.623fa7702p-1, 0x1.605816058p-1, 0x1.5e75bb8dp-1,
+      0x1.5c9882b94p-1, 0x1.5ac056b02p-1, 0x1.58ed23082p-1,
+      0x1.571ed3c5p-1,  0x1.555555556p-1, 0x1.5390948f4p-1,
+      0x1.51d07eae2p-1, 0x1.501501502p-1, 0x1.4e5e0a73p-1,
+      0x1.4cab88726p-1, 0x1.4afd6a052p-1, 0x1.49539e3b2p-1,
+      0x1.47ae147aep-1, 0x1.460cbc7f6p-1, 0x1.446f86562p-1,
+      0x1.42d6625d6p-1, 0x1.414141414p-1, 0x1.3fb013fbp-1,
+      0x1.3e22cbce4p-1, 0x1.3c995a47cp-1, 0x1.3b13b13b2p-1,
+      0x1.3991c2c18p-1, 0x1.381381382p-1, 0x1.3698df3dep-1,
+      0x1.3521cfb2cp-1, 0x1.33ae45b58p-1, 0x1.323e34a2cp-1,
+      0x1.30d19013p-1,  0x1.2f684bda2p-1, 0x1.2e025c04cp-1,
+      0x1.2c9fb4d82p-1, 0x1.2b404ad02p-1, 0x1.29e4129e4p-1,
+      0x1.288b01288p-1, 0x1.27350b882p-1, 0x1.25e22708p-1,
+      0x1.24924924ap-1, 0x1.23456789ap-1, 0x1.21fb78122p-1,
+      0x1.20b470c68p-1, 0x1.1f7047dc2p-1, 0x1.1e2ef3b4p-1,
+      0x1.1cf06ada2p-1, 0x1.1bb4a4046p-1, 0x1.1a7b9611ap-1,
+      0x1.19453808cp-1, 0x1.181181182p-1, 0x1.16e068942p-1,
+      0x1.15b1e5f76p-1, 0x1.1485f0e0ap-1, 0x1.135c81136p-1,
+      0x1.12358e75ep-1, 0x1.111111112p-1, 0x1.0fef010fep-1,
+      0x1.0ecf56be6p-1, 0x1.0db20a89p-1,  0x1.0c9714fbcp-1,
+      0x1.0b7e6ec26p-1, 0x1.0a6810a68p-1, 0x1.0953f3902p-1,
+      0x1.084210842p-1, 0x1.073260a48p-1, 0x1.0624dd2f2p-1,
+      0x1.05197f7d8p-1, 0x1.041041042p-1, 0x1.03091b52p-1,
+      0x1.020408102p-1, 0x1.01010101p-1,  0x1p-1
+    };
+
+  static const double lix[] = {
+      0x0p+0,               -0x1.6fe50b6f1eafap-7, -0x1.6e79685c160d5p-6,
+     -0x1.11cd1d51955bap-5, -0x1.6bad37591e03p-5,  -0x1.c4dfab908ddb5p-5,
+     -0x1.0eb389fab4795p-4, -0x1.3aa2fdd26ae99p-4, -0x1.663f6faca846bp-4,
+     -0x1.918a16e4cb157p-4, -0x1.bc84240a78a13p-4, -0x1.e72ec1181cfb1p-4,
+     -0x1.08c588cd964e4p-3, -0x1.1dcd19759f2e3p-3, -0x1.32ae9e27627c6p-3,
+     -0x1.476a9f989a58ap-3, -0x1.5c01a39fa6533p-3, -0x1.70742d4eed455p-3,
+     -0x1.84c2bd02d6434p-3, -0x1.98edd077e9f0ap-3, -0x1.acf5e2db31eeap-3,
+     -0x1.c0db6cddaa82dp-3, -0x1.d49ee4c33121ap-3, -0x1.e840be751d775p-3,
+     -0x1.fbc16b9003e0bp-3, -0x1.0790adbae3fcp-2,  -0x1.11307dad465b5p-2,
+     -0x1.1ac05b2924cc5p-2, -0x1.24407ab0cc41p-2,  -0x1.2db10fc4ea424p-2,
+     -0x1.37124cea58697p-2, -0x1.406463b1d455dp-2, -0x1.49a784bcbaa37p-2,
+     -0x1.52dbdfc4f341dp-2, -0x1.5c01a39ff2c9bp-2, -0x1.6518fe46abaa5p-2,
+     -0x1.6e221cd9d6933p-2, -0x1.771d2ba7f5791p-2, -0x1.800a56315ee2ap-2,
+     -0x1.88e9c72df8611p-2, -0x1.91bba891d495fp-2, -0x1.9a8023920fa4dp-2,
+     -0x1.a33760a7fbca6p-2, -0x1.abe18797d2effp-2, -0x1.b47ebf734b923p-2,
+     -0x1.bd0f2e9eb2b84p-2, -0x1.c592fad2be1aap-2, -0x1.ce0a4923cf5e6p-2,
+     -0x1.d6753e02f4ebcp-2, -0x1.ded3fd445afp-2,   -0x1.e726aa1e558fep-2,
+     -0x1.ef6d67325ba38p-2, -0x1.f7a8568c8aea6p-2, -0x1.ffd799a81be87p-2,
+     0x1.f804ae8d33c4p-2,    0x1.efec61b04af4ep-2,  0x1.e7df5fe572606p-2,
+     0x1.dfdd89d5b0009p-2,   0x1.d7e6c0abbd924p-2,  0x1.cffae611a74d6p-2,
+     0x1.c819dc2d8578cp-2,   0x1.c043859e5bdbcp-2,  0x1.b877c57b47c04p-2,
+     0x1.b0b67f4f29a66p-2,   0x1.a8ff97183ed07p-2,  0x1.a152f14293c74p-2,
+     0x1.99b072a9289cap-2,   0x1.921800927e284p-2,  0x1.8a8980ac4113p-2,
+     0x1.8304d90c2859dp-2,   0x1.7b89f02cbd49ap-2,  0x1.7418aceb84ab1p-2,
+     0x1.6cb0f68656c95p-2,   0x1.6552b49993dc2p-2,  0x1.5dfdcf1eacd7bp-2,
+     0x1.56b22e6b97c18p-2,   0x1.4f6fbb2ce6943p-2,  0x1.48365e6957b42p-2,
+     0x1.4106017c0dbcfp-2,   0x1.39de8e15727d9p-2,  0x1.32bfee37489bcp-2,
+     0x1.2baa0c34989c3p-2,   0x1.249cd2b177fd5p-2,  0x1.1d982c9d50468p-2,
+     0x1.169c0536677acp-2,   0x1.0fa848045f67bp-2,  0x1.08bce0d9a7c6p-2,
+     0x1.01d9bbcf66a2cp-2,   0x1.f5fd8a90e2d85p-3,  0x1.e857d3d3af1e5p-3,
+     0x1.dac22d3ec5f4ep-3,   0x1.cd3c712db459ap-3,  0x1.bfc67a7ff3c22p-3,
+     0x1.b2602497678f4p-3,   0x1.a5094b555a1f8p-3,  0x1.97c1cb136b96fp-3,
+     0x1.8a8980ac8652dp-3,   0x1.7d60496c83f66p-3,  0x1.7046031c7cdafp-3,
+     0x1.633a8bf460335p-3,   0x1.563dc2a08b102p-3,  0x1.494f863bbc1dep-3,
+     0x1.3c6fb6507a37ep-3,   0x1.2f9e32d5257ecp-3,  0x1.22dadc2a627efp-3,
+     0x1.1625931802e49p-3,   0x1.097e38cef9519p-3,  0x1.f9c95dc138295p-4,
+     0x1.e0b1ae90505f6p-4,   0x1.c7b528b5fcffap-4,  0x1.aed391abb17a1p-4,
+     0x1.960caf9bd35eap-4,   0x1.7d60496e3edebp-4,  0x1.64ce26bf2108ep-4,
+     0x1.4c560fe5b573bp-4,   0x1.33f7cde24adfbp-4,  0x1.1bb32a5ed9353p-4,
+     0x1.0387efbd3006ep-4,   0x1.d6ebd1f1d0955p-5,  0x1.a6f9c37a8beabp-5,
+     0x1.77394c9d6762cp-5,   0x1.47aa07358e1a4p-5,  0x1.184b8e4d490efp-5,
+     0x1.d23afc4d95c78p-6,   0x1.743ee8678a7cbp-6,  0x1.16a21e243bf78p-6,
+     0x1.72c7ba20c907ep-7,   0x1.720d9c0536e17p-8,  0x0p+0
+  };
+
+  double z = x;
+  uint32_t ux = asuint (x);
+  uint32_t ax = ux & (~0u >> 1);
+  if (__glibc_unlikely (ux >= 0x17fu << 23))
+    { /* x <= -1 */
+      if (ux == (0x17fu << 23))
+	return __math_divzerof (1);
+      if (ux > (0x1ffu << 23))
+	return x + x;		   /* nan */
+      return __math_invalidf (x);
+    }
+  else if (__glibc_unlikely (ax >= (0xff << 23)))
+    { /* +inf, nan  */
+      if (ax > (0xff << 23))
+	return x + x; /* nan  */
+      return INFINITY;
+    }
+  else if (__glibc_likely (ax < 0x3cb7aa26u))
+    { /* |x| < 0x1.6f544cp-6  */
+      double z2 = z * z, z4 = z2 * z2;
+      if ( __glibc_likely(ax < 0x3b9d9d34u))
+	{ /* |x| < 0x1.3b3a68p-8 */
+	  if (__glibc_likely (ax < 0x39638a7eu))
+	    { /* |x| < 0x1.c714fcp-13 */
+	      if (__glibc_likely (ax < 0x329c5639u))
+		{ /* |x| < 0x1.38ac72p-26 */
+		  static const double c[] =
+		    {
+		      0x1.71547652b82fep+0, -0x1.71547652b82ffp-1
+		    };
+		  return z * (c[0] + z * c[1]);
+		}
+	      else
+		{
+		  if (__glibc_unlikely (ux == 0x32ff7045u))
+		    return 0x1.70851ap-25f - 0x1.8p-80f;
+		  if (__glibc_unlikely (ux == 0xb395efbbu))
+		    return -0x1.b0a00ap-24f + 0x1p-76f;
+		  if (__glibc_unlikely (ux == 0x35a14df7u))
+		    return 0x1.d16d2p-20f + 0x1p-72f;
+		  if (__glibc_unlikely (ux == 0x3841cb81u))
+		    return 0x1.17949ep-14f + 0x1p-67f;
+		  static const double c[] =
+		    {
+		      0x1.71547652b82fep+0, -0x1.71547652b82fdp-1,
+		      0x1.ec709ead0c9a7p-2, -0x1.7154773c1cb29p-2
+		    };
+		  return z * ((c[0] + z * c[1]) + z2 * (c[2] + z * c[3]));
+		}
+	    }
+	  else
+	    {
+	      if (__glibc_unlikely (ux == 0xbac9363du))
+		return -0x1.2282aap-9f + 0x1p-61f;
+	      static const double c[] =
+	       	{
+		  0x1.71547652b82fep+0, -0x1.71547652b83p-1,
+		  0x1.ec709dc28f51bp-2, -0x1.7154765157748p-2,
+		  0x1.2778a510a3682p-2, -0x1.ec745df1551fcp-3
+		};
+	      return z
+		     * ((c[0] + z * c[1]) + z2 * (c[2] + z * c[3])
+			+ z4 * ((c[4] + z * c[5])));
+	    }
+	}
+      else
+	{
+	  static const double c[] =
+	    {
+	      0x1.71547652b82fep+0, -0x1.71547652b82fbp-1,
+	      0x1.ec709dc3b6a73p-2, -0x1.71547652dc09p-2,
+	      0x1.2776c1a88901p-2,  -0x1.ec7095bd4d208p-3,
+	      0x1.a66bec7fc8f7p-3,  -0x1.71a900fc3f3f9p-3
+	    };
+	  return z
+		 * ((c[0] + z * c[1]) + z2 * (c[2] + z * c[3])
+		    + z4 * ((c[4] + z * c[5]) + z2 * (c[6] + z * c[7])));
+	}
+    }
+  else
+    { /* |x| >= 0x1.6f544cp-6 */
+      float h, l;
+      /* With gcc 6.3.0, if we return 0x1.e90026p+4f + 0x1.fp-21
+	 in the second exceptional case, with rounding up it yields
+	 0x1.e90026p+4 which is incorrect, thus we use this workaround. See
+	 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112367. */
+      if (__glibc_unlikely (ux == 0x52928e33u))
+	{
+	  h = 0x1.318ffap+5f;
+	  l = 0x1.fp-20f;
+	  return h + l;
+	}
+      if (__glibc_unlikely (ux == 0x4ebd09e3u))
+	{
+	  h = 0x1.e90026p+4f;
+	  l = 0x1.fp-21;
+	  return h + l;
+	}
+      uint64_t tp = asuint64 (z + 1.0);
+      uint64_t m = tp & (~(uint64_t) 0 >> 12);
+      int e = (tp >> 52) - 0x3ff;
+      int j = (m + ((int64_t) 1 << (52 - 8))) >> (52 - 7), k = j > 53;
+      e += k;
+      double xd = asdouble (m | (uint64_t) 0x3ff << 52);
+      z = fma (xd, ix[j], -1.0);
+      static const double c[] =
+	{
+	  0x1.71547652b82fep+0, -0x1.71547652b82ffp-1, 0x1.ec709dc32988bp-2,
+	  -0x1.715476521ec2bp-2, 0x1.277801a1ad904p-2, -0x1.ec731704d6a88p-3
+       	};
+      double z2 = z * z;
+      double c0 = c[0] + z * c[1];
+      double c2 = c[2] + z * c[3];
+      double c4 = c[4] + z * c[5];
+      c0 += z2 * (c2 + z2 * c4);
+      return (z * c0 - lix[j]) + e;
+    }
+}
+libm_alias_float (__log2p1, log2p1)
diff --git a/sysdeps/loongarch/lp64/libm-test-ulps b/sysdeps/loongarch/lp64/libm-test-ulps
index 5d407a49fe..b59d68202e 100644
--- a/sysdeps/loongarch/lp64/libm-test-ulps
+++ b/sysdeps/loongarch/lp64/libm-test-ulps
@@ -1252,22 +1252,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/m68k/m680x0/fpu/libm-test-ulps b/sysdeps/m68k/m680x0/fpu/libm-test-ulps
index 7fef8942ae..3964b83b81 100644
--- a/sysdeps/m68k/m680x0/fpu/libm-test-ulps
+++ b/sysdeps/m68k/m680x0/fpu/libm-test-ulps
@@ -1091,19 +1091,15 @@  double: 1
 
 Function: "log2p1":
 double: 1
-float: 2
 
 Function: "log2p1_downward":
 double: 1
-float: 2
 
 Function: "log2p1_towardzero":
 double: 1
-float: 2
 
 Function: "log2p1_upward":
 double: 1
-float: 2
 
 Function: "logp1":
 double: 1
diff --git a/sysdeps/mips/mips32/libm-test-ulps b/sysdeps/mips/mips32/libm-test-ulps
index f9d7bf8598..f1d0543aea 100644
--- a/sysdeps/mips/mips32/libm-test-ulps
+++ b/sysdeps/mips/mips32/libm-test-ulps
@@ -1003,22 +1003,18 @@  float: 3
 
 Function: "log2p1":
 double: 1
-float: 2
 ldouble: 1
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 1
 
 Function: "log_downward":
diff --git a/sysdeps/mips/mips64/libm-test-ulps b/sysdeps/mips/mips64/libm-test-ulps
index 4f3c82d64c..fecd998560 100644
--- a/sysdeps/mips/mips64/libm-test-ulps
+++ b/sysdeps/mips/mips64/libm-test-ulps
@@ -1260,22 +1260,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 1
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/powerpc/fpu/libm-test-ulps b/sysdeps/powerpc/fpu/libm-test-ulps
index ddbd184e58..f775c56618 100644
--- a/sysdeps/powerpc/fpu/libm-test-ulps
+++ b/sysdeps/powerpc/fpu/libm-test-ulps
@@ -1569,25 +1569,21 @@  ldouble: 4
 
 Function: "log2p1":
 double: 2
-float: 2
 float128: 3
 ldouble: 2
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 float128: 3
 ldouble: 4
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 float128: 2
 ldouble: 5
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 float128: 3
 ldouble: 6
 
diff --git a/sysdeps/powerpc/nofpu/libm-test-ulps b/sysdeps/powerpc/nofpu/libm-test-ulps
index c79dfcc2cc..a732166765 100644
--- a/sysdeps/powerpc/nofpu/libm-test-ulps
+++ b/sysdeps/powerpc/nofpu/libm-test-ulps
@@ -1317,22 +1317,18 @@  ldouble: 4
 
 Function: "log2p1":
 double: 1
-float: 2
 ldouble: 2
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 4
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 5
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 6
 
 Function: "log_downward":
diff --git a/sysdeps/riscv/nofpu/libm-test-ulps b/sysdeps/riscv/nofpu/libm-test-ulps
index 4caf84f316..739d04bc5c 100644
--- a/sysdeps/riscv/nofpu/libm-test-ulps
+++ b/sysdeps/riscv/nofpu/libm-test-ulps
@@ -1209,7 +1209,6 @@  ldouble: 1
 
 Function: "log2p1":
 double: 1
-float: 1
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/riscv/rvd/libm-test-ulps b/sysdeps/riscv/rvd/libm-test-ulps
index e9c4b72c04..f6bb6e05e1 100644
--- a/sysdeps/riscv/rvd/libm-test-ulps
+++ b/sysdeps/riscv/rvd/libm-test-ulps
@@ -1252,22 +1252,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/s390/fpu/libm-test-ulps b/sysdeps/s390/fpu/libm-test-ulps
index a42c9f273a..b444d4475e 100644
--- a/sysdeps/s390/fpu/libm-test-ulps
+++ b/sysdeps/s390/fpu/libm-test-ulps
@@ -1251,22 +1251,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/sparc/fpu/libm-test-ulps b/sysdeps/sparc/fpu/libm-test-ulps
index 3bee496247..c7f8531d6d 100644
--- a/sysdeps/sparc/fpu/libm-test-ulps
+++ b/sysdeps/sparc/fpu/libm-test-ulps
@@ -1260,22 +1260,18 @@  ldouble: 1
 
 Function: "log2p1":
 double: 1
-float: 2
 ldouble: 3
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 ldouble: 2
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 ldouble: 3
 
 Function: "log_downward":
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index ffb1d4f3c9..de19bf26f7 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -1910,25 +1910,21 @@  float: 1
 
 Function: "log2p1":
 double: 2
-float: 2
 float128: 3
 ldouble: 4
 
 Function: "log2p1_downward":
 double: 2
-float: 2
 float128: 3
 ldouble: 4
 
 Function: "log2p1_towardzero":
 double: 2
-float: 2
 float128: 2
 ldouble: 4
 
 Function: "log2p1_upward":
 double: 2
-float: 2
 float128: 3
 ldouble: 5