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180 lines
6.7 KiB
180 lines
6.7 KiB
7 years ago
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Backport of this upstream commit (with libm-test.inc adjustments):
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commit 374f7f61214967bb4e2257695aeeeecc2a77f369
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Author: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
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Date: Fri Mar 14 07:35:43 2014 -0500
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PowerPC: remove wrong ceill implementation for PowerPC64
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The ceill assembly implementation (sysdeps/powerpc/powerpc64/fpu/s_ceill.S)
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returns wrong results for some inputs where first double is a exact
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integer and the precision is determined by second long double.
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Checking on implementation comments and history, I am very confident the
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assembly implementation was based on a version before commit
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5c68d401698a58cf7da150d9cce769fa6679ba5f that fixes BZ#2423 (Errors in
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long double (ldbl-128ibm) rounding functions in glibc-2.4).
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By just removing the implementation and make the build select
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sysdeps/ieee754/ldbl-128ibm/s_ceill.c instead fixes the failing math.
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Fixes BZ#16701.
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Index: b/math/libm-test.inc
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===================================================================
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--- a/math/libm-test.inc
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+++ b/math/libm-test.inc
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@@ -2241,6 +2241,15 @@ ceil_test (void)
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TEST_f_f (ceil, -72057594037927936.75L, -72057594037927936.0L);
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TEST_f_f (ceil, -72057594037927937.5L, -72057594037927937.0L);
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+ /* Check cases where first double is a exact integer higher than 2^52 and
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+ the precision is determined by second long double for IBM long double. */
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+ TEST_f_f (ceil, 34503599627370498.515625L, 34503599627370499.0L);
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+ TEST_f_f (ceil, -34503599627370498.515625L, -34503599627370498.0L);
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+# if LDBL_MANT_DIG >= 106
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+ TEST_f_f (ceil, 1192568192774434123539907640624.484375L, 1192568192774434123539907640625.0L);
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+ TEST_f_f (ceil, -1192568192774434123539907640624.484375L, -1192568192774434123539907640624.0L);
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+# endif
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+
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TEST_f_f (ceil, 10141204801825835211973625643007.5L, 10141204801825835211973625643008.0L);
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TEST_f_f (ceil, 10141204801825835211973625643008.25L, 10141204801825835211973625643009.0L);
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TEST_f_f (ceil, 10141204801825835211973625643008.5L, 10141204801825835211973625643009.0L);
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Index: b/sysdeps/powerpc/powerpc64/fpu/s_ceill.S
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===================================================================
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--- a/sysdeps/powerpc/powerpc64/fpu/s_ceill.S
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+++ /dev/null
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@@ -1,132 +0,0 @@
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-/* s_ceill.S IBM extended format long double version.
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- Copyright (C) 2004, 2006 Free Software Foundation, Inc.
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- This file is part of the GNU C Library.
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-
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- The GNU C Library is free software; you can redistribute it and/or
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- modify it under the terms of the GNU Lesser General Public
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- License as published by the Free Software Foundation; either
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- version 2.1 of the License, or (at your option) any later version.
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-
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- The GNU C Library is distributed in the hope that it will be useful,
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- but WITHOUT ANY WARRANTY; without even the implied warranty of
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- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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- Lesser General Public License for more details.
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-
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- You should have received a copy of the GNU Lesser General Public
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- License along with the GNU C Library; if not, see
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- <http://www.gnu.org/licenses/>. */
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-
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-#include <sysdep.h>
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-#include <math_ldbl_opt.h>
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-
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- .section ".toc","aw"
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-.LC0: /* 2**52 */
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- .tc FD_43300000_0[TC],0x4330000000000000
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-
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- .section ".text"
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-
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-/* long double [fp1,fp2] ceill (long double x [fp1,fp2])
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- IEEE 1003.1 ceil function.
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-
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- PowerPC64 long double uses the IBM extended format which is
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- represented two 64-floating point double values. The values are
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- non-overlapping giving an effective precision of 106 bits. The first
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- double contains the high order bits of mantisa and is always ceiled
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- to represent a normal ceiling of long double to double. Since the
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- long double value is sum of the high and low values, the low double
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- normally has the opposite sign to compensate for the this ceiling.
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-
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- For long double there are two cases:
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- 1) |x| < 2**52, all the integer bits are in the high double.
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- ceil the high double and set the low double to -0.0.
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- 2) |x| >= 2**52, ceiling involves both doubles.
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- See the comment before lable .L2 for details.
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- */
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-
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-ENTRY (__ceill)
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- mffs fp11 /* Save current FPU rounding mode. */
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- lfd fp13,.LC0@toc(2)
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- fabs fp0,fp1
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- fabs fp9,fp2
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- fsub fp12,fp13,fp13 /* generate 0.0 */
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- fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
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- fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
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- bnl- cr7,.L2
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- mtfsfi 7,2 /* Set rounding mode toward +inf. */
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- fneg fp2,fp12
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- ble- cr6,.L1
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- fadd fp1,fp1,fp13 /* x+= TWO52; */
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- fsub fp1,fp1,fp13 /* x-= TWO52; */
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- fabs fp1,fp1 /* if (x == 0.0) */
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-.L0:
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- mtfsf 0x01,fp11 /* restore previous rounding mode. */
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- blr /* x = 0.0; */
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-.L1:
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- bge- cr6,.L0 /* if (x < 0.0) */
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- fsub fp1,fp1,fp13 /* x-= TWO52; */
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- fadd fp1,fp1,fp13 /* x+= TWO52; */
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- fcmpu cr5,fp1,fp12 /* if (x > 0.0) */
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- mtfsf 0x01,fp11 /* restore previous rounding mode. */
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- fnabs fp1,fp1 /* if (x == 0.0) */
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- blr /* x = -0.0; */
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-
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-/* The high double is > TWO52 so we need to round the low double and
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- perhaps the high double. In this case we have to round the low
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- double and handle any adjustment to the high double that may be
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- caused by rounding (up). This is complicated by the fact that the
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- high double may already be rounded and the low double may have the
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- opposite sign to compensate.This gets a bit tricky so we use the
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- following algorithm:
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-
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- tau = floor(x_high/TWO52);
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- x0 = x_high - tau;
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- x1 = x_low + tau;
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- r1 = rint(x1);
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- y_high = x0 + r1;
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- y_low = x0 - y_high + r1;
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- return y; */
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-.L2:
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- fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */
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- fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */
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- fcmpu cr5,fp2,fp12 /* if (x_low > 0.0) */
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- bgelr- cr7 /* return x; */
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- beqlr- cr0
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- mtfsfi 7,2 /* Set rounding mode toward +inf. */
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- fdiv fp8,fp1,fp13 /* x_high/TWO52 */
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-
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- bng- cr6,.L6 /* if (x > 0.0) */
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- fctidz fp0,fp8
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- fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
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- bng cr5,.L4 /* if (x_low > 0.0) */
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- fmr fp3,fp1
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- fmr fp4,fp2
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- b .L5
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-.L4: /* if (x_low < 0.0) */
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- fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
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- fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
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-.L5:
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- fadd fp5,fp4,fp13 /* r1 = r1 + TWO52; */
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- fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */
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- b .L9
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-.L6: /* if (x < 0.0) */
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- fctidz fp0,fp8
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- fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
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- bnl cr5,.L7 /* if (x_low < 0.0) */
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- fmr fp3,fp1
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- fmr fp4,fp2
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- b .L8
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-.L7: /* if (x_low > 0.0) */
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- fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
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- fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
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-.L8:
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- fsub fp5,fp4,fp13 /* r1-= TWO52; */
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- fadd fp5,fp5,fp13 /* r1+= TWO52; */
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-.L9:
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- mtfsf 0x01,fp11 /* restore previous rounding mode. */
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- fadd fp1,fp3,fp5 /* y_high = x0 + r1; */
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- fsub fp2,fp3,fp1 /* y_low = x0 - y_high + r1; */
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- fadd fp2,fp2,fp5
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- blr
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-END (__ceill)
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-
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-long_double_symbol (libm, __ceill, ceill)
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