Implement C23 log2p1

C23 adds various <math.h> function families originally defined in TS
18661-4.  Add the log2p1 functions (log2(1+x): like log1p, but for
base-2 logarithms).

This illustrates the intended structure of implementations of all
these function families: define them initially with a type-generic
template implementation.  If someone wishes to add type-specific
implementations, it is likely such implementations can be both faster
and more accurate than the type-generic one and can then override it
for types for which they are implemented (adding benchmarks would be
desirable in such cases to demonstrate that a new implementation is
indeed faster).

The test inputs are copied from those for log1p.  Note that these
changes make gen-auto-libm-tests depend on MPFR 4.2 (or later).

The bulk of the changes are fairly generic for any such new function.
(sysdeps/powerpc/nofpu/Makefile only needs changing for those
type-generic templates that use fabs.)

Tested for x86_64 and x86, and with build-many-glibcs.py.

NEWS

@@ -21,6 +21,13 @@ Major new features:
   by _GNU_SOURCE, or by compiling with the GCC options -std=c23,
   -std=gnu23, -std=c2x or -std=gnu2x.
 
+* The following ISO C23 function families (introduced in TS
+  18661-4:2015) are now supported in <math.h>.  Each family includes
+  functions for float, double, long double, _FloatN and _FloatNx, and a
+  type-generic macro in <tgmath.h>.
+
+  - Logarithmic functions: log2p1.
+
 * A new tunable, glibc.rtld.enable_secure, used to run a program
   as if it were a setuid process. This is currently a testing tool to allow
   more extensive verification tests for AT_SECURE programs and not meant to

manual/math.texi

@@ -754,6 +754,20 @@ They are computed in a way that is accurate even if @var{x} is
 near zero.
 @end deftypefun
 
+@deftypefun double log2p1 (double @var{x})
+@deftypefunx float log2p1f (float @var{x})
+@deftypefunx {long double} log2p1l (long double @var{x})
+@deftypefunx _FloatN log2p1fN (_Float@var{N} @var{x})
+@deftypefunx _FloatNx log2p1fNx (_Float@var{N}x @var{x})
+@standards{TS 18661-4:2015, math.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+These functions return a value equivalent to @w{@code{log2 (1 + @var{x})}}.
+They are computed in a way that is accurate even if @var{x} is
+near zero.
+
+The @code{log2p1} functions are from TS 18661-4:2015.
+@end deftypefun
+
 @cindex complex exponentiation functions
 @cindex complex logarithm functions
 

math/Makefile

@@ -127,6 +127,7 @@ gen-libm-calls = \
   s_fminimum_numF \
   s_fminmagF \
   s_iseqsigF \
+  s_log2p1F \
   s_nanF \
   s_nextdownF \
   s_significandF \
@@ -650,6 +651,7 @@ libm-test-funcs-auto = \
   log10 \
   log1p \
   log2 \
+  log2p1 \
   pow \
   sin \
   sincos \
@@ -892,6 +894,7 @@ tgmath3-macros = \
   log10 \
   log1p \
   log2 \
+  log2p1 \
   logb \
   lrint \
   lround \
@@ -1264,6 +1267,7 @@ CFLAGS-e_log.c += -fno-builtin-logl
 CFLAGS-w_log10.c += -fno-builtin-log10l
 CFLAGS-w_log1p.c += -fno-builtin-log1pl
 CFLAGS-e_log2.c += -fno-builtin-log2l
+CFLAGS-s_log2p1.c += -fno-builtin-log2p1l
 CFLAGS-s_logb.c += -fno-builtin-logbl
 CFLAGS-s_lrint.c += -fno-builtin-lrintl
 CFLAGS-s_lround.c += -fno-builtin-lroundl
@@ -1389,6 +1393,7 @@ CFLAGS-e_log.c += -fno-builtin-logf32x -fno-builtin-logf64
 CFLAGS-w_log10.c += -fno-builtin-log10f32x -fno-builtin-log10f64
 CFLAGS-w_log1p.c += -fno-builtin-log1pf32x -fno-builtin-log1pf64
 CFLAGS-e_log2.c += -fno-builtin-log2f32x -fno-builtin-log2f64
+CFLAGS-s_log2p1.c += -fno-builtin-log2p1f32x -fno-builtin-log2p1f64
 CFLAGS-s_logb.c += -fno-builtin-logbf32x -fno-builtin-logbf64
 CFLAGS-s_lrint.c += -fno-builtin-lrintf32x -fno-builtin-lrintf64
 CFLAGS-s_lround.c += -fno-builtin-lroundf32x -fno-builtin-lroundf64
@@ -1503,6 +1508,7 @@ CFLAGS-e_logf.c += -fno-builtin-logf32
 CFLAGS-w_log10f.c += -fno-builtin-log10f32
 CFLAGS-w_log1pf.c += -fno-builtin-log1pf32
 CFLAGS-e_log2f.c += -fno-builtin-log2f32
+CFLAGS-s_log2p1f.c += -fno-builtin-log2p1f32
 CFLAGS-s_logbf.c += -fno-builtin-logbf32
 CFLAGS-s_lrintf.c += -fno-builtin-lrintf32
 CFLAGS-s_lroundf.c += -fno-builtin-lroundf32

math/Versions

@@ -639,4 +639,10 @@ libm {
     # No SVID compatible error handling.
     exp10;
   }
+  GLIBC_2.40 {
+    # Functions not involving _Float64x or _Float128, for all configurations.
+    log2p1; log2p1f; log2p1l; log2p1f32; log2p1f64; log2p1f32x;
+    # Functions involving _Float64x or _Float128, for some configurations.
+    log2p1f64x; log2p1f128;
+  }
 }

math/auto-libm-test-in

@@ -6664,6 +6664,57 @@ log2 min
 log2 min_subnorm
 log2 max
 
+log2p1 0
+log2p1 -0
+log2p1 e-1
+log2p1 -0.25
+log2p1 -0.875
+log2p1 0x1p-5
+log2p1 0x1p-10
+log2p1 0x1p-15
+log2p1 0x1p-20
+log2p1 0x1p-25
+log2p1 0x1p-30
+log2p1 0x1p-35
+log2p1 0x1p-40
+log2p1 0x1p-45
+log2p1 0x1p-50
+log2p1 0x1p-55
+log2p1 0x1p-60
+log2p1 0x1p-100
+log2p1 0x1p-600
+log2p1 0x1p-10000
+log2p1 min
+log2p1 min_subnorm
+log2p1 -min
+log2p1 -min_subnorm
+log2p1 0x1p10
+log2p1 0x1p20
+log2p1 0x1p30
+log2p1 0x1p50
+log2p1 0x1p60
+log2p1 0x1p100
+log2p1 0x1p1000
+log2p1 0x6.a0cf42befce9ed4085ef59254b48p-4
+log2p1 max
+
+log2p1 0x7.2a4368p-4
+log2p1 0x6.d3a118p-4
+log2p1 0x5.03f228p+0
+log2p1 0x7.264963888ac9p-4
+log2p1 0x8.786bdp-4
+log2p1 0x7.89dc17790eeb4p-4
+log2p1 0x9.81ccf8887c24a7bp-4
+log2p1 0xa.5028608bd65f38dp-4
+log2p1 0x5.bf78873e20a2d468p-4
+log2p1 0x7.aa5198p-4
+log2p1 0x2.564fap+0
+log2p1 0x7.fc242a2235222ef8p-4
+log2p1 -0x4.f37d3c9ce0b14bdd86eb157df5d4p-4
+log2p1 0x7.2eca50c4d93196362b4f37f6e8dcp-4
+log2p1 -0x6.3fef3067427e43dfcde9e48f74bcp-4
+log2p1 0x6.af53d00fd2845d4772260ef5adc4p-4
+
 mul 0 0
 mul 0 -0
 mul -0 0

math/bits/mathcalls.h

@@ -112,6 +112,9 @@ __MATHCALL (modf,, (_Mdouble_ __x, _Mdouble_ *__iptr)) __nonnull ((2));
 #if __GLIBC_USE (IEC_60559_FUNCS_EXT_C23)
 /* Compute exponent to base ten.  */
 __MATHCALL_VEC (exp10,, (_Mdouble_ __x));
+
+/* Return log2(1 + X).  */
+__MATHCALL (log2p1,, (_Mdouble_ __x));
 #endif
 
 #if defined __USE_XOPEN_EXTENDED || defined __USE_ISOC99

math/gen-auto-libm-tests.c

@@ -580,6 +580,7 @@ static test_function test_functions[] =
     FUNC_mpfr_f_f ("log10", mpfr_log10, false),
     FUNC_mpfr_f_f ("log1p", mpfr_log1p, false),
     FUNC_mpfr_f_f ("log2", mpfr_log2, false),
+    FUNC_mpfr_f_f ("log2p1", mpfr_log2p1, false),
     FUNC_mpfr_ff_f ("mul", mpfr_mul, true),
     FUNC_mpfr_ff_f ("pow", mpfr_pow, false),
     FUNC_mpfr_f_f ("sin", mpfr_sin, false),

math/gen-tgmath-tests.py

@@ -743,6 +743,7 @@ class Tests(object):
                 self.add_tests(prefix + fn, ret, ['r'] * args)
         # TS 18661-4 functions.
         self.add_tests('exp10', 'r', ['r'])
+        self.add_tests('log2p1', 'r', ['r'])
         # C23 functions.
         self.add_tests('fmaximum', 'r', ['r', 'r'])
         self.add_tests('fmaximum_mag', 'r', ['r', 'r'])

math/libm-test-log2p1.inc

@@ -0,0 +1,53 @@
+/* Test log2p1.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include "libm-test-driver.c"
+
+static const struct test_f_f_data log2p1_test_data[] =
+  {
+    TEST_f_f (log2p1, -1, minus_infty, DIVIDE_BY_ZERO_EXCEPTION|ERRNO_ERANGE),
+    TEST_f_f (log2p1, -2, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+    TEST_f_f (log2p1, -max_value, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM|XFAIL_ROUNDING_IBM128_LIBGCC),
+    TEST_f_f (log2p1, minus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+
+    TEST_f_f (log2p1, plus_infty, plus_infty, ERRNO_UNCHANGED),
+    TEST_f_f (log2p1, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_f_f (log2p1, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_f_f (log2p1, snan_value, qnan_value, INVALID_EXCEPTION),
+    TEST_f_f (log2p1, -snan_value, qnan_value, INVALID_EXCEPTION),
+
+    AUTO_TESTS_f_f (log2p1),
+  };
+
+static void
+log2p1_test (void)
+{
+  ALL_RM_TEST (log2p1, 0, log2p1_test_data, RUN_TEST_LOOP_f_f, END);
+}
+
+static void
+do_test (void)
+{
+  log2p1_test ();
+}
+
+/*
+ * Local Variables:
+ * mode:c
+ * End:
+ */

math/s_log2p1_template.c

@@ -0,0 +1,43 @@
+/* Return base-2 logarithm of 1 + X.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <math.h>
+#include <math-underflow.h>
+
+FLOAT
+M_DECL_FUNC (__log2p1) (FLOAT x)
+{
+  if (__glibc_unlikely (islessequal (x, M_LIT (-1.0))))
+    {
+      if (x == -1)
+	__set_errno (ERANGE);
+      else
+	__set_errno (EDOM);
+    }
+  if (isless (M_FABS (x), M_EPSILON / 4))
+    {
+      /* Avoid spurious underflows when log1p underflows but log2p1
+	 should not.  */
+      FLOAT ret = M_MLIT (M_LOG2E) * x;
+      math_check_force_underflow (ret);
+      return ret;
+    }
+  return M_MLIT (M_LOG2E) * M_SUF (__log1p) (x);
+}
+declare_mgen_alias (__log2p1, log2p1);

math/test-tgmath.c

@@ -48,7 +48,7 @@ volatile int count_cdouble;
 volatile int count_cfloat;
 volatile int count_cldouble;
 
-#define NCALLS     158
+#define NCALLS     160
 #define NCALLS_INT 4
 #define NCCALLS    47
 
@@ -255,6 +255,7 @@ F(compile_test) (void)
   a = exp2 (exp2 (x));
   a = exp10 (exp10 (x));
   b = log2 (log2 (a));
+  a = log2p1 (log2p1 (x));
   a = pow (pow (x, a), pow (c, b));
   b = sqrt (sqrt (a));
   a = hypot (hypot (x, b), hypot (c, a));
@@ -368,6 +369,7 @@ F(compile_test) (void)
       a = exp2 (y);
       a = exp10 (y);
       a = log2 (y);
+      a = log2p1 (y);
       a = pow (y, y);
       a = sqrt (y);
       a = hypot (y, y);
@@ -641,6 +643,14 @@ TYPE
   return x;
 }
 
+TYPE
+(F(log2p1)) (TYPE x)
+{
+  ++count;
+  P ();
+  return x;
+}
+
 TYPE
 (F(pow)) (TYPE x, TYPE y)
 {

math/tgmath.h

@@ -874,6 +874,9 @@
 #if __GLIBC_USE (IEC_60559_FUNCS_EXT_C23)
 /* Compute exponent to base ten.  */
 #define exp10(Val) __TGMATH_UNARY_REAL_ONLY (Val, exp10)
+
+/* Return log2(1 + X).  */
+#define log2p1(Val) __TGMATH_UNARY_REAL_ONLY (Val, log2p1)
 #endif
 
 

sysdeps/i386/i686/fpu/multiarch/libm-test-ulps

@@ -1424,6 +1424,30 @@ float: 1
 float128: 1
 ldouble: 1
 
+Function: "log2p1":
+double: 1
+float: 1
+float128: 3
+ldouble: 2
+
+Function: "log2p1_downward":
+double: 1
+float: 1
+float128: 3
+ldouble: 4
+
+Function: "log2p1_towardzero":
+double: 1
+float: 1
+float128: 2
+ldouble: 4
+
+Function: "log2p1_upward":
+double: 1
+float: 1
+float128: 2
+ldouble: 5
+
 Function: "log_downward":
 double: 1
 float128: 1

sysdeps/ieee754/ldbl-128ibm-compat/Versions

@@ -137,6 +137,9 @@ libm {
     __fminimum_magieee128;
     __fminimum_mag_numieee128;
   }
+  GLIBC_2.40 {
+    __log2p1ieee128;
+  }
 }
 libc {
   LDBL_IBM128_VERSION {

sysdeps/ieee754/ldbl-opt/Makefile

@@ -51,7 +51,8 @@ libnldbl-calls = asprintf dprintf fprintf fscanf fwprintf fwscanf iovfscanf \
 		 roundeven fromfp ufromfp fromfpx ufromfpx fadd dadd \
 		 fdiv ddiv ffma dfma fmul dmul fsqrt dsqrt fsub dsub \
 		 fmaximum fmaximum_mag fmaximum_num fmaximum_mag_num \
-		 fminimum fminimum_mag fminimum_num fminimum_mag_num
+		 fminimum fminimum_mag fminimum_num fminimum_mag_num \
+		 log2p1
 libnldbl-routines = $(libnldbl-calls:%=nldbl-%)
 libnldbl-inhibit-o = $(object-suffixes)
 libnldbl-static-only-routines = $(libnldbl-routines)
@@ -151,6 +152,7 @@ CFLAGS-nldbl-log.c = -fno-builtin-logl
 CFLAGS-nldbl-log10.c = -fno-builtin-log10l
 CFLAGS-nldbl-log1p.c = -fno-builtin-log1pl
 CFLAGS-nldbl-log2.c = -fno-builtin-log2l
+CFLAGS-nldbl-log2p1.c = -fno-builtin-log2p1l
 CFLAGS-nldbl-logb.c = -fno-builtin-logbl
 CFLAGS-nldbl-lrint.c = -fno-builtin-lrintl
 CFLAGS-nldbl-lround.c = -fno-builtin-lroundl

sysdeps/ieee754/ldbl-opt/nldbl-log2p1.c

@@ -0,0 +1,8 @@
+#include "nldbl-compat.h"
+
+double
+attribute_hidden
+log2p1l (double x)
+{
+  return log2p1 (x);
+}

sysdeps/mach/hurd/i386/libm.abilist

@@ -1181,3 +1181,11 @@ GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
 GLIBC_2.35 hypot F
 GLIBC_2.35 hypotf F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/mach/hurd/x86_64/libm.abilist

@@ -1038,3 +1038,11 @@ GLIBC_2.38 ynf32x F
 GLIBC_2.38 ynf64 F
 GLIBC_2.38 ynf64x F
 GLIBC_2.38 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/powerpc/nofpu/Makefile

@@ -54,4 +54,5 @@ CFLAGS-s_fmaximum_magl.c += -fno-builtin-fabsl
 CFLAGS-s_fmaximum_mag_numl.c += -fno-builtin-fabsl
 CFLAGS-s_fminimum_magl.c += -fno-builtin-fabsl
 CFLAGS-s_fminimum_mag_numl.c += -fno-builtin-fabsl
+CFLAGS-s_log2p1l.c += -fno-builtin-fabsl
 endif

sysdeps/unix/sysv/linux/aarch64/libm.abilist

@@ -1149,3 +1149,11 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/alpha/libm.abilist

@@ -1308,3 +1308,11 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/arc/libm.abilist

@@ -757,3 +757,9 @@ GLIBC_2.35 fminimumf64 F
 GLIBC_2.35 fminimuml F
 GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/arm/be/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.4 y1l F
 GLIBC_2.4 yn F
 GLIBC_2.4 ynf F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/arm/le/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.4 y1l F
 GLIBC_2.4 yn F
 GLIBC_2.4 ynf F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/csky/libm.abilist

@@ -823,3 +823,9 @@ GLIBC_2.35 fminimumf64 F
 GLIBC_2.35 fminimuml F
 GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/hppa/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
 GLIBC_2.4 exp2l F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/i386/libm.abilist

@@ -1188,3 +1188,11 @@ GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
 GLIBC_2.35 hypot F
 GLIBC_2.35 hypotf F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/loongarch/lp64/libm.abilist

@@ -1028,3 +1028,11 @@ GLIBC_2.36 ynf32x F
 GLIBC_2.36 ynf64 F
 GLIBC_2.36 ynf64x F
 GLIBC_2.36 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.4 y1l F
 GLIBC_2.4 yn F
 GLIBC_2.4 ynf F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist

@@ -884,3 +884,9 @@ GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
 GLIBC_2.35 hypot F
 GLIBC_2.35 hypotf F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/microblaze/be/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/microblaze/le/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/mips/mips32/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
 GLIBC_2.4 exp2l F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/mips/mips64/libm.abilist

@@ -1149,3 +1149,11 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/nios2/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/or1k/libm.abilist

@@ -757,3 +757,9 @@ GLIBC_2.35 ynf32 F
 GLIBC_2.35 ynf32x F
 GLIBC_2.35 ynf64 F
 GLIBC_2.35 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist

@@ -995,3 +995,9 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist

@@ -994,3 +994,9 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libm.abilist

@@ -988,3 +988,9 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libm.abilist

@@ -1321,3 +1321,12 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 __log2p1ieee128 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/riscv/rv32/libm.abilist

@@ -1028,3 +1028,11 @@ GLIBC_2.35 fminimumf64x F
 GLIBC_2.35 fminimuml F
 GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/riscv/rv64/libm.abilist

@@ -1125,3 +1125,11 @@ GLIBC_2.35 fminimumf64x F
 GLIBC_2.35 fminimuml F
 GLIBC_2.35 fsqrt F
 GLIBC_2.35 fsqrtl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist

@@ -1252,3 +1252,11 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist

@@ -1252,3 +1252,11 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/sh/be/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
 GLIBC_2.4 exp2l F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/sh/le/libm.abilist

@@ -848,3 +848,9 @@ GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
 GLIBC_2.4 exp2l F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist

@@ -1259,3 +1259,11 @@ GLIBC_2.4 truncl F
 GLIBC_2.4 y0l F
 GLIBC_2.4 y1l F
 GLIBC_2.4 ynl F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist

@@ -1149,3 +1149,11 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/x86_64/64/libm.abilist

@@ -1182,3 +1182,11 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist

@@ -1182,3 +1182,11 @@ GLIBC_2.35 hypotf F
 GLIBC_2.38 fmod F
 GLIBC_2.38 fmodf F
 GLIBC_2.39 exp10 F
+GLIBC_2.40 log2p1 F
+GLIBC_2.40 log2p1f F
+GLIBC_2.40 log2p1f128 F
+GLIBC_2.40 log2p1f32 F
+GLIBC_2.40 log2p1f32x F
+GLIBC_2.40 log2p1f64 F
+GLIBC_2.40 log2p1f64x F
+GLIBC_2.40 log2p1l F

sysdeps/x86_64/fpu/libm-test-ulps

@@ -1847,6 +1847,30 @@ float: 1
 Function: "log2_vlen8_avx2":
 float: 1
 
+Function: "log2p1":
+double: 1
+float: 1
+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: 4
+
+Function: "log2p1_upward":
+double: 1
+float: 2
+float128: 2
+ldouble: 5
+
 Function: "log_downward":
 float: 2
 float128: 1