mirror of git://sourceware.org/git/glibc.git
PowerPC: remove wrong roundl implementation for PowerPC64
The roundl assembly implementation
(sysdeps/powerpc/powerpc64/fpu/s_roundl.S)
returns wrong results for some inputs where first double is a exact
integer and the precision is determined by second long double.
Checking on implementation comments and history, I am very confident the
assembly implementation was based on a version before commit
5c68d40169 that fixes BZ#2423 (Errors in
long double (ldbl-128ibm) rounding functions in glibc-2.4).
By just removing the implementation and make the build select
sysdeps/ieee754/ldbl-128ibm/s_roundl.c instead fixes the failing math.
This fixes 16707.
This commit is contained in:
Adhemerval Zanella
parent
98fb27a373
commit
c7de502503
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@ -1,3 +1,10 @@
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2014-03-14 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
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[BZ #16707]
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* sysdeps/powerpc/powerpc64/fpu/s_roundl.S: Remove wrong
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implementation.
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* math/libm-test.inc (round_test_data): Add more tests.
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2014-03-14 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
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[BZ #16706]
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2
NEWS
2
NEWS
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@ -11,7 +11,7 @@ Version 2.20
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15347, 15804, 15894, 16447, 16532, 16545, 16574, 16600, 16609, 16610,
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16611, 16613, 16623, 16632, 16639, 16642, 16670, 16674, 16677, 16683,
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16689, 16695, 16701, 16706.
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16689, 16695, 16701, 16706, 16707.
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* The am33 port, which had not worked for several years, has been removed
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from ports.
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@ -10629,6 +10629,15 @@ static const struct test_f_f_data round_test_data[] =
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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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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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@ -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) 2004-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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#include <sysdep.h>
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#include <math_ldbl_opt.h>
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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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/* 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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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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/* 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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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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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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long_double_symbol (libm, __roundl, roundl)
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