[Bug math/2423] New: Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[Bug math/2423] New: Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

The implementations of the (IBM double double format) long double
(./ldbld-128ibm/) for ceill, floorl, rintl, roundl, truncl, rounds incorrectly
when the integer portion is contained in th ehigh double, but the fractional
postion is contained in the low double.

-- 
           Summary: Errors in long double (ldbl-128ibm) rounding functions
                    in glibc-2.4
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: sjmunroe at us dot ibm dot com
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: powerpc-gnu-linux
  GCC host triplet: powerpc-gnu-linux
GCC target triplet: powerpc-gnu-linux


http://sourceware.org/bugzilla/show_bug.cgi?id=2423

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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

------- Additional Comments From sjmunroe at us dot ibm dot com  2006-03-06 20:44 -------
Created an attachment (id=904)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=904&action=view)
Sample of error output.


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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

------- Additional Comments From sjmunroe at us dot ibm dot com  2006-03-06 20:48 -------
Created an attachment (id=905)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=905&action=view)
Standalone test cases.


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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

------- Additional Comments From sjmunroe at us dot ibm dot com  2006-03-06 20:55 -------
Created an attachment (id=906)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=906&action=view)
Proposed patch

Proposed patch for ./ldbl-128ibm/ implementations of ceill, floorl, rintl,
roundl, truncl

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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2006-03-07 08:24 -------
Subject: Bug 2423

CVSROOT:	/cvs/glibc
Module name:	libc
Branch: 	fedora-branch
Changes by:	jakub@sources.redhat.com	2006-03-07 08:24:13

Modified files:
	.              : ChangeLog 
	math           : libm-test.inc 
	sysdeps/ieee754/ldbl-128ibm: e_fmodl.c e_rem_pio2l.c math_ldbl.h 
	                             s_ceill.c s_floorl.c s_rintl.c 
	                             s_roundl.c s_truncl.c 
	sysdeps/powerpc/fpu: fegetround.c fenv_libc.h fesetround.c 
Added files:
	sysdeps/powerpc/fpu: math_ldbl.h 

Log message:
	2006-03-03  Steven Munroe  <sjmunroe@us.ibm.com>
	Alan Modra  <amodra@bigpond.net.au>
	
	[BZ #2423]
	* math/libm-test.inc [TEST_LDOUBLE] (ceil_test, floor_test, rint_test,
	round_test, trunc_test): Add new tests.
	
	* sysdeps/powerpc/fpu/fenv_libc.h (__fegetround, __fesetround):
	Define inline implementations.
	* sysdeps/powerpc/fpu/fegetround.c: Use __fegetround.
	* sysdeps/powerpc/fpu/fesetround.c: Use __fesetround.
	
	* sysdeps/ieee754/ldbl-128ibm/math_ldbl.h
	(EXTRACT_IBM_EXTENDED_MANTISSA, INSERT_IBM_EXTENDED_MANTISSA):
	Removed, replaced with.
	(ldbl_extract_mantissa, ldbl_insert_mantissa, ldbl_pack, ldbl_unpack,
	ldbl_canonicalise, ldbl_nearbyint): Define inline utility
	functions for IBM long double format.
	* sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Replace
	EXTRACT_IBM_EXTENDED_MANTISSA and INSERT_IBM_EXTENDED_MANTISSA
	with ldbl_extract_mantissa and ldbl_insert_mantissa.
	* sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c (__ieee754_rem_pio2l):
	Replace EXTRACT_IBM_EXTENDED_MANTISSA with ldbl_extract_mantissa.
	(ldbl_extract_mantissa, ldbl_insert_mantissa): Defined.
	
	* sysdeps/ieee754/ldbl-128ibm/s_ceill.c (__ceill): Handle rounding
	that spans doubles in IBM long double format.
	* sysdeps/ieee754/ldbl-128ibm/s_floorl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_rintl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_roundl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Likewise.
	* sysdeps/powerpc/fpu/math_ldbl.h: New file.
	* sysdeps/powerpc/powerpc64/fpu/s_rintl.S: Removed.

Patches:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/ChangeLog.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.8782.2.172&r2=1.8782.2.173
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/math/libm-test.inc.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.61.2.6&r2=1.61.2.7
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/e_fmodl.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/math_ldbl.h.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_ceill.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.2&r2=1.1.2.3
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_floorl.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.2&r2=1.1.2.3
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_rintl.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_roundl.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_truncl.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.1.2.1&r2=1.1.2.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/powerpc/fpu/math_ldbl.h.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=NONE&r2=1.1.2.1
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/powerpc/fpu/fegetround.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.2&r2=1.2.4.1
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/powerpc/fpu/fenv_libc.h.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.2&r2=1.2.4.1
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/powerpc/fpu/fesetround.c.diff?cvsroot=glibc&only_with_tag=fedora-branch&r1=1.3.4.1&r2=1.3.4.2



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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2006-03-16 11:46 -------
Subject: Bug 2423

CVSROOT:	/cvs/glibc
Module name:	libc
Changes by:	roland@sources.redhat.com	2006-03-16 11:46:30

Modified files:
	math           : libm-test.inc 

Log message:
	2006-03-07  Jakub Jelinek  <jakub@redhat.com>
	
	[BZ #2423]
	* math/libm-test.inc [TEST_LDOUBLE] (ceil_test, floor_test, rint_test,
	round_test, trunc_test): Only run some of the new tests if
	LDBL_MANT_DIG > 100.
	2006-03-03  Steven Munroe  <sjmunroe@us.ibm.com> Alan Modra  <amodra@bigpond.net.au>
	
	[BZ #2423]
	* math/libm-test.inc [TEST_LDOUBLE] (ceil_test, floor_test, rint_test,
	round_test, trunc_test): Add new tests.
	* sysdeps/ieee754/ldbl-128ibm/math_ldbl.h
	(EXTRACT_IBM_EXTENDED_MANTISSA, INSERT_IBM_EXTENDED_MANTISSA):
	Removed, replaced with ...
	(ldbl_extract_mantissa, ldbl_insert_mantissa, ldbl_pack, ldbl_unpack,
	ldbl_canonicalise, ldbl_nearbyint): New functions.
	* sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Replace
	EXTRACT_IBM_EXTENDED_MANTISSA and INSERT_IBM_EXTENDED_MANTISSA
	with ldbl_extract_mantissa and ldbl_insert_mantissa.
	* sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c (__ieee754_rem_pio2l):
	Replace EXTRACT_IBM_EXTENDED_MANTISSA with ldbl_extract_mantissa.
	(ldbl_extract_mantissa, ldbl_insert_mantissa): New inline functions.
	* sysdeps/ieee754/ldbl-128ibm/s_ceill.c (__ceill): Handle rounding
	that spans doubles in IBM long double format.
	* sysdeps/ieee754/ldbl-128ibm/s_floorl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_rintl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_roundl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_rintl.S: File removed.

Patches:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/math/libm-test.inc.diff?cvsroot=glibc&r1=1.69&r2=1.70



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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2006-03-16 11:46 -------
Subject: Bug 2423

CVSROOT:	/cvs/glibc
Module name:	libc
Changes by:	roland@sources.redhat.com	2006-03-16 11:46:37

Modified files:
	sysdeps/ieee754/ldbl-128ibm: s_ceill.c s_floorl.c s_rintl.c 
	                             math_ldbl.h e_rem_pio2l.c e_fmodl.c 
	                             s_truncl.c s_roundl.c 
Removed files:
	sysdeps/powerpc/powerpc64/fpu: s_rintl.S 

Log message:
	2006-03-03  Steven Munroe  <sjmunroe@us.ibm.com> Alan Modra  <amodra@bigpond.net.au>
	
	[BZ #2423]
	* math/libm-test.inc [TEST_LDOUBLE] (ceil_test, floor_test, rint_test,
	round_test, trunc_test): Add new tests.
	* sysdeps/ieee754/ldbl-128ibm/math_ldbl.h
	(EXTRACT_IBM_EXTENDED_MANTISSA, INSERT_IBM_EXTENDED_MANTISSA):
	Removed, replaced with ...
	(ldbl_extract_mantissa, ldbl_insert_mantissa, ldbl_pack, ldbl_unpack,
	ldbl_canonicalise, ldbl_nearbyint): New functions.
	* sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Replace
	EXTRACT_IBM_EXTENDED_MANTISSA and INSERT_IBM_EXTENDED_MANTISSA
	with ldbl_extract_mantissa and ldbl_insert_mantissa.
	* sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c (__ieee754_rem_pio2l):
	Replace EXTRACT_IBM_EXTENDED_MANTISSA with ldbl_extract_mantissa.
	(ldbl_extract_mantissa, ldbl_insert_mantissa): New inline functions.
	* sysdeps/ieee754/ldbl-128ibm/s_ceill.c (__ceill): Handle rounding
	that spans doubles in IBM long double format.
	* sysdeps/ieee754/ldbl-128ibm/s_floorl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_rintl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_roundl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_rintl.S: File removed.

Patches:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/powerpc/powerpc64/fpu/s_rintl.S.diff?cvsroot=glibc&r1=1.1&r2=NONE
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_ceill.c.diff?cvsroot=glibc&r1=1.2&r2=1.3
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_floorl.c.diff?cvsroot=glibc&r1=1.2&r2=1.3
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_rintl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/math_ldbl.h.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/e_fmodl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_truncl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_roundl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2



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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2006-04-23 17:43 -------
You cannot change the rounding mode in library functions.  This would make using
floating point operations in signal handlers unpredictable.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING


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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

------- Additional Comments From sjmunroe at us dot ibm dot com  2006-05-11 13:55 -------
hmmm, the alternative is to simulate the operation with integer ops. But this is
generic code...

I'll look to using the double rounding equivelent, instead of changing the
rounding mode inline, to get the desired effect. Slightly less efficient but
more  general.

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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[sjmunroe at us dot ibm dot com]

------- Additional Comments From sjmunroe at us dot ibm dot com  2006-06-14 18:29 -------
hhhmm its harder then I thought. The IBM extended format ABI states clearly that
it only works correctly in the default rounding mode (round to nearest). 

Given that assumption it, seems unnecessary to guard against the user changing
the rounding to a non-default mode, as basic arithmatic and canonicalization may
be incorrect anyway.

So it seems the best solution is to simply remove the fesetround where possible.
This works for ceill, floorl, roundl, and truncl as they are never tested in the
non-default rounding mode. llroundl is clean because it is only using
feraiseexcept (handle overflow) and does not mess with rounding.

This also helps with Bugzilla 2749 as soft-fp does not provide fenv_libc.h. We
need to either remove the #include <fenv_libc.h> and any related fe* calls, or
replace <fenv_libc.h> with <fenv.h>

llrintl and rintl are another matter as these are explictly tested in all
rounding modes (and yes I did this to myself :( ). 

At the moment I don't have a good answer for these yet other then disabling the
non-default rounding mode tests for IBM extended.


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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2007-01-17 13:00 -------
Subject: Bug 2423

CVSROOT:	/cvs/glibc
Module name:	libc
Changes by:	jakub@sourceware.org	2007-01-17 13:00:11

Modified files:
	.              : ChangeLog 
	sysdeps/ieee754/ldbl-128ibm: s_fabsl.c s_roundl.c s_truncl.c 
	                             s_copysignl.c s_ceill.c s_floorl.c 

Log message:
	[BZ #2749]
	* sysdeps/ieee754/ldbl-128ibm/s_copysignl.c: Include
	<math_ldbl_opt.h>.  Remove weak_alias.  Use long_double_symbol macro.
	(__copysignl): Use signbit() for comparison.
	* sysdeps/ieee754/ldbl-128ibm/s_fabsl.c (__fabsl): Correct parms for
	SET_LDOUBLE_WORDS64.
	
	[BZ #2423, #2749]
	* sysdeps/ieee754/ldbl-128ibm/s_ceill.c: Don't include <fenv_libc.h>.
	(__ceill): Remove calls to fegetround(), fesetround().
	* sysdeps/ieee754/ldbl-128ibm/s_floorl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_roundl.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Likewise.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/ChangeLog.diff?cvsroot=glibc&r1=1.10480&r2=1.10481
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_fabsl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_roundl.c.diff?cvsroot=glibc&r1=1.2&r2=1.3
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_truncl.c.diff?cvsroot=glibc&r1=1.2&r2=1.3
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_copysignl.c.diff?cvsroot=glibc&r1=1.1&r2=1.2
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_ceill.c.diff?cvsroot=glibc&r1=1.3&r2=1.4
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/sysdeps/ieee754/ldbl-128ibm/s_floorl.c.diff?cvsroot=glibc&r1=1.3&r2=1.4



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[Bug math/2423] Errors in long double (ldbl-128ibm) rounding functions in glibc-2.4

[aj at suse dot de]

------- Additional Comments From aj at suse dot de  2007-02-18 13:54 -------
should be fixed now.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=2423

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