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PowerPC: remove wrong truncl implementation for PowerPC64

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The truncl assembly implementation (sysdeps/powerpc/powerpc64/fpu/s_truncl.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_truncl.c instead it fixes tgammal
issues regarding wrong result sign.
This commit is contained in:
Adhemerval Zanella 2014-01-08 05:10:41 -06:00
parent 3ff6304ee7
commit 38f3458175
4 changed files with 9 additions and 125 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
ChangeLog
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@ -1,4 +1,11 @@
2013-01-08 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
2014-01-08 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
[BZ #16414]
* sysdeps/powerpc/powerpc64/fpu/s_truncl.S: Remove wrong
implementation.
* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Remove bogus comment.
2014-01-08 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
* sysdeps/powerpc/fpu/libm-test-ulps: Update.

2
NEWS
View File

@ -24,7 +24,7 @@ Version 2.19
16103, 16112, 16143, 16144, 16146, 16150, 16151, 16153, 16167, 16172,
16195, 16214, 16245, 16271, 16274, 16283, 16289, 16293, 16314, 16316,
16330, 16337, 16338, 16356, 16365, 16366, 16369, 16372, 16375, 16379,
16384, 16385, 16386, 16387, 16390, 16400, 16407, 16408.
16384, 16385, 16386, 16387, 16390, 16400, 16407, 16408, 16414.
* Slovenian translations for glibc messages have been contributed by the
Translation Project's Slovenian team of translators.

3
sysdeps/ieee754/ldbl-128ibm/s_truncl.c
View File

@ -17,9 +17,6 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This has been coded in assembler because GCC makes such a mess of it
when it's coded in C. */
#include <math.h>
#include <math_ldbl_opt.h>
#include <float.h>

120
sysdeps/powerpc/powerpc64/fpu/s_truncl.S
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@ -1,120 +0,0 @@
/* long double trunc function.
IBM extended format long double version.
Copyright (C) 2004-2014 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
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <math_ldbl_opt.h>
.section ".toc","aw"
.LC0: /* 2**52 */
.tc FD_43300000_0[TC],0x4330000000000000
.LC1: /* 0.5 */
.tc FD_3fe00000_0[TC],0x3fe0000000000000
.section ".text"
/* long double [fp1,fp2] truncl (long double x [fp1,fp2]) */
ENTRY (__truncl)
mffs fp11 /* Save current FPU rounding mode. */
lfd fp13,.LC0@toc(2)
fabs fp0,fp1
fabs fp9,fp2
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnl- cr7,.L2
mtfsfi 7,1 /* Set rounding mode toward 0. */
ble- cr6,.L1
fneg fp2,fp12
fadd fp1,fp1,fp13 /* x+= TWO52; */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) x = 0.0; */
.L0:
mtfsf 0x01,fp11 /* restore previous rounding mode. */
blr
.L1:
fneg fp2,fp12
bge- cr6,.L0 /* if (x < 0.0) */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fadd fp1,fp1,fp13 /* x+= TWO52; */
fnabs fp1,fp1 /* if (x == 0.0) x = -0.0; */
mtfsf 0x01,fp11 /* restore previous rounding mode. */
blr
/* The high double is > TWO52 so we need to round the low double and
perhaps the high double. In this case we have to round the low
double and handle any adjustment to the high double that may be
caused by rounding (up). This is complicated by the fact that the
high double may already be rounded and the low double may have the
opposite sign to compensate.This gets a bit tricky so we use the
following algorithm:
tau = floor(x_high/TWO52);
x0 = x_high - tau;
x1 = x_low + tau;
r1 = rint(x1);
y_high = x0 + r1;
y_low = x0 - y_high + r1;
return y; */
.L2:
fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */
fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */
fcmpu cr5,fp2,fp12 /* if (x_low > 0.0) */
bgelr- cr7 /* return x; */
beqlr- cr0
mtfsfi 7,1 /* Set rounding mode toward 0. */
fdiv fp8,fp1,fp13 /* x_high/TWO52 */
bng- cr6,.L6 /* if (x > 0.0) */
fctidz fp0,fp8
fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
fadd fp8,fp8,fp8 /* tau++; Make tau even */
bng cr5,.L4 /* if (x_low > 0.0) */
fmr fp3,fp1
fmr fp4,fp2
b .L5
.L4: /* if (x_low < 0.0) */
fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
.L5:
fadd fp5,fp4,fp13 /* r1 = r1 + TWO52; */
fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */
b .L9
.L6: /* if (x < 0.0) */
fctidz fp0,fp8
fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
fadd fp8,fp8,fp8 /* tau++; Make tau even */
bnl cr5,.L7 /* if (x_low < 0.0) */
fmr fp3,fp1
fmr fp4,fp2
b .L8
.L7: /* if (x_low > 0.0) */
fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
.L8:
fsub fp5,fp4,fp13 /* r1-= TWO52; */
fadd fp5,fp5,fp13 /* r1+= TWO52; */
.L9:
mtfsf 0x01,fp11 /* restore previous rounding mode. */
fadd fp1,fp3,fp5 /* y_high = x0 + r1; */
fsub fp2,fp3,fp1 /* y_low = x0 - y_high + r1; */
fadd fp2,fp2,fp5
blr
END (__truncl)
long_double_symbol (libm, __truncl, truncl)