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180 lines
6.7 KiB
180 lines
6.7 KiB
Backport of this upstream commit (with libm-test.inc adjustments): |
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commit c7de50250367167d8c9f35594b264f6a0af8dd0c |
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Author: Adhemerval Zanella <azanella@linux.vnet.ibm.com> |
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Date: Fri Mar 14 12:49:45 2014 -0500 |
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PowerPC: remove wrong roundl implementation for PowerPC64 |
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The roundl assembly implementation |
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(sysdeps/powerpc/powerpc64/fpu/s_roundl.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_roundl.c instead fixes the failing math. |
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This fixes 16707. |
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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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@@ -9268,6 +9268,15 @@ round_test (void) |
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TEST_f_f (round, -72057594037927936.75L, -72057594037927937.0L); |
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TEST_f_f (round, -72057594037927937.5L, -72057594037927938.0L); |
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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 (round, 34503599627370498.515625L, 34503599627370499.0L); |
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+ TEST_f_f (round, -34503599627370498.515625L, -34503599627370499.0L); |
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+# if LDBL_MANT_DIG >= 106 |
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+ TEST_f_f (round, 1192568192774434123539907640624.484375L, 1192568192774434123539907640624.0L); |
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+ TEST_f_f (round, -1192568192774434123539907640624.484375L, -1192568192774434123539907640624.0L); |
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+# endif |
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+ |
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TEST_f_f (round, 10141204801825835211973625643007.5L, 10141204801825835211973625643008.0L); |
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TEST_f_f (round, 10141204801825835211973625643008.25L, 10141204801825835211973625643008.0L); |
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TEST_f_f (round, 10141204801825835211973625643008.5L, 10141204801825835211973625643009.0L); |
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Index: b/sysdeps/powerpc/powerpc64/fpu/s_roundl.S |
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=================================================================== |
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--- a/sysdeps/powerpc/powerpc64/fpu/s_roundl.S |
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+++ /dev/null |
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@@ -1,132 +0,0 @@ |
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-/* long double round function. |
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- 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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-.LC1: /* 0.5 */ |
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- .tc FD_3fe00000_0[TC],0x3fe0000000000000 |
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- .section ".text" |
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- |
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-/* long double [fp1,fp2] roundl (long double x [fp1,fp2]) |
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- IEEE 1003.1 round function. IEEE specifies "round to the nearest |
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- integer value, rounding halfway cases away from zero, regardless of |
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- the current rounding mode." However PowerPC Architecture defines |
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- "Round to Nearest" as "Choose the best approximation. In case of a |
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- tie, choose the one that is even (least significant bit o).". |
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- So we can't use the PowerPC "Round to Nearest" mode. Instead we set |
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- "Round toward Zero" mode and round by adding +-0.5 before rounding |
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- to the integer value. */ |
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- |
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-ENTRY (__roundl) |
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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 7,1 /* Set rounding mode toward 0. */ |
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- lfd fp10,.LC1@toc(2) |
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- ble- cr6,.L1 |
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- fneg fp2,fp12 |
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- fadd fp1,fp1,fp10 /* x+= 0.5; */ |
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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) x = 0.0; */ |
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-.L0: |
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- mtfsf 0x01,fp11 /* restore previous rounding mode. */ |
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- blr |
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-.L1: |
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- fsub fp9,fp1,fp10 /* x-= 0.5; */ |
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- fneg fp2,fp12 |
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- bge- cr6,.L0 /* if (x < 0.0) */ |
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- fsub fp1,fp9,fp13 /* x-= TWO52; */ |
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- fadd fp1,fp1,fp13 /* x+= TWO52; */ |
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- fnabs fp1,fp1 /* if (x == 0.0) x = -0.0; */ |
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- mtfsf 0x01,fp11 /* restore previous rounding mode. */ |
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- blr |
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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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- lfd fp10,.LC1@toc(2) |
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- bgelr- cr7 /* return x; */ |
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- beqlr- cr0 |
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- mtfsfi 7,1 /* Set rounding mode toward 0. */ |
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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,fp10 /* r1 = x1 + 0.5; */ |
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- fadd fp5,fp5,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,fp10 /* r1 = x1 - 0.5; */ |
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- fsub fp5,fp5,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 (__roundl) |
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- |
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-long_double_symbol (libm, __roundl, roundl)
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