NetBSD Problem Report #59310

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Date: Thu, 17 Apr 2025 13:21:24 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: t_fe_round:fe_nearbyint_rint tests are failing
X-Send-Pr-Version: www-1.0

>Number:         59310
>Category:       port-sparc64
>Synopsis:       t_fe_round:fe_nearbyint_rint tests are failing
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-sparc64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 17 13:25:00 +0000 2025
>Last-Modified:  Thu Apr 17 14:00:04 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The SparcBSD Roundation
>Environment:
>Description:
Failures are happening both under qemu and on real hardware.  Curiously, they are not happening on sparc32 -- only sparc64.

t_fe_round:fe_nearbyint_rint failures (https://www.netbsd.org/~martin/sparc64-atf/965_atf.html#lib_libm_t_fe_round_fe_nearbyint_rint):

*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [0] FE_DOWNWARD nearbyintl(3.750000): got 4.000000, expected 3
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [0] FE_DOWNWARD rintl(3.750000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [0] FE_DOWNWARD rintl(3.750000): got 4.000000, expected 3
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [1] FE_DOWNWARD rintl(-3.750000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [4] FE_DOWNWARD nearbyintl(-9223.062500): got -9223.000000, expected -9224
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [4] FE_DOWNWARD rintl(-9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [4] FE_DOWNWARD rintl(-9223.062500): got -9223.000000, expected -9224
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [5] FE_DOWNWARD nearbyintl(9222.937500): got 9223.000000, expected 9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [5] FE_DOWNWARD rintl(9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [5] FE_DOWNWARD rintl(9222.937500): got 9223.000000, expected 9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [6] FE_DOWNWARD rintl(-9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [7] FE_DOWNWARD rintl(9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [10] FE_UPWARD nearbyintl(-123.750000): got -124.000000, expected -123
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [10] FE_UPWARD rintl(-123.750000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [10] FE_UPWARD rintl(-123.750000): got -124.000000, expected -123
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [11] FE_UPWARD rintl(123.750000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [12] FE_UPWARD rintl(-9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [13] FE_UPWARD rintl(9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [14] FE_UPWARD nearbyintl(-9222.937500): got -9223.000000, expected -9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [14] FE_UPWARD rintl(-9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [14] FE_UPWARD rintl(-9222.937500): got -9223.000000, expected -9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [15] FE_UPWARD nearbyintl(9223.062500): got 9223.000000, expected 9224
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [15] FE_UPWARD rintl(9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [15] FE_UPWARD rintl(9223.062500): got 9223.000000, expected 9224
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [16] FE_TOWARDZERO nearbyintl(1.937500): got 2.000000, expected 1
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [16] FE_TOWARDZERO rintl(1.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [16] FE_TOWARDZERO rintl(1.937500): got 2.000000, expected 1
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [17] FE_TOWARDZERO nearbyintl(-1.937500): got -2.000000, expected -1
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [17] FE_TOWARDZERO rintl(-1.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [17] FE_TOWARDZERO rintl(-1.937500): got -2.000000, expected -1
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [18] FE_TOWARDZERO rintl(0.250000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [19] FE_TOWARDZERO rintl(9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [20] FE_TOWARDZERO nearbyintl(9222.937500): got 9223.000000, expected 9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [20] FE_TOWARDZERO rintl(9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [20] FE_TOWARDZERO rintl(9222.937500): got 9223.000000, expected 9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [21] FE_TOWARDZERO nearbyintl(-9222.937500): got -9223.000000, expected -9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [21] FE_TOWARDZERO rintl(-9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:294: [21] FE_TOWARDZERO rintl(-9222.937500): got -9223.000000, expected -9222
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [24] FE_TONEAREST rintl(-9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [25] FE_TONEAREST rintl(9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [26] FE_TONEAREST rintl(-9222.937500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [27] FE_TONEAREST rintl(9223.062500) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [28] FE_TONEAREST rintl(-9223.531250) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [29] FE_TONEAREST rintl(9222.468750) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [30] FE_TONEAREST rintl(-9222.468750) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:263: [31] FE_TONEAREST rintl(9223.531250) failed to raise FE_INEXACT

t_fe_round:fe_nearbyintl_rintl failures (https://www.netbsd.org/~martin/sparc64-atf/965_atf.html#lib_libm_t_fe_round_fe_nearbyintl_rintl):

*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [0] FE_TOWARDZERO rintl(9007199254740992.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [1] FE_DOWNWARD rintl(9007199254740992.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [2] FE_UPWARD rintl(9007199254740992.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [2] FE_UPWARD rintl(9007199254740992.500000): got 9007199254740992.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [2] FE_UPWARD nearbyintl(9007199254740992.500000): got 9007199254740992.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [3] FE_TONEAREST rintl(9007199254740992.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [4] FE_TOWARDZERO rintl(9007199254740993.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [4] FE_TOWARDZERO rintl(9007199254740993.500000): got 9007199254740994.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [4] FE_TOWARDZERO nearbyintl(9007199254740993.500000): got 9007199254740994.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [5] FE_DOWNWARD rintl(9007199254740993.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [5] FE_DOWNWARD rintl(9007199254740993.500000): got 9007199254740994.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:421: [5] FE_DOWNWARD nearbyintl(9007199254740993.500000): got 9007199254740994.000000, expected 9007199254740993
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [6] FE_UPWARD rintl(9007199254740993.500000) failed to raise FE_INEXACT
*** Check failed: /home/martin/current/src/tests/lib/libm/t_fe_round.c:390: [7] FE_TONEAREST rintl(9007199254740993.500000) failed to raise FE_INEXACT
>How-To-Repeat:
cd /usr/tests/lib/libm
atf-run t_fe_round | atf-report
>Fix:
Yes, please!

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59310 CVS commit: src/tests/lib/libm
Date: Thu, 17 Apr 2025 13:45:22 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Apr 17 13:45:22 UTC 2025

 Modified Files:
 	src/tests/lib/libm: t_fe_round.c

 Log Message:
 t_fe_round: Mark xfail on sparc64.

 PR port-sparc64/59310: t_fe_round:fe_nearbyint_rint tests are failing


 To generate a diff of this commit:
 cvs rdiff -u -r1.20 -r1.21 src/tests/lib/libm/t_fe_round.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: Taylor R Campbell <riastradh@NetBSD.org>
To: gnats-bugs@NetBSD.org, netbsd-bugs@NetBSD.org
Cc: 
Subject: Re: port-sparc64/59310: t_fe_round:fe_nearbyint_rint tests are failing
Date: Thu, 17 Apr 2025 13:58:25 +0000

 All the test cases that are failing are in long double functions with
 non-default rounding modes.

 On sparc64, long double is implemented via softfloat ABI, from what I
 understand -- `objdump --disassemble=3Drintl libm.so' shows various
 _Qp_* function calls:

 00000000000776e0 <rintl>:
 ...
    77760:       40 04 54 c8     call  18ca80 <_Qp_stoq@plt>
 ...
    77790:       40 04 57 b4     call  18d660 <_Qp_add@plt>
 ...
    777b8:       40 04 55 32     call  18cc80 <_Qp_sub@plt>
 ...
    777f4:       40 04 55 a3     call  18ce80 <_Qp_feq@plt>
 ...
    77824:       40 04 54 97     call  18ca80 <_Qp_stoq@plt>
 ...
    77850:       40 04 57 84     call  18d660 <_Qp_add@plt>

 I bet the reason these are failing is that the C99 fesetround() in
 libm doesn't update _softfloat_float_rounding_mode, so the _Qp_*
 functions are all working in round-to-nearest:

     227 int
     228 fesetround(int round)
     229 {
     230 	fenv_t r;
     231=20
     232 	_DIAGASSERT((round & ~_ROUND_MASK) =3D=3D 0);
     233 	if (round & ~_ROUND_MASK)
     234 		return -1;
     235=20
     236 	__stxfsr(&r);
     237 	r &=3D ~(_ROUND_MASK << _ROUND_SHIFT);
     238 	r |=3D round << _ROUND_SHIFT;
     239 	__ldxfsr(r);
     240=20
     241 	/* Success */
     242 	return 0;
     243 }

 https://nxr.netbsd.org/xref/src/lib/libm/arch/sparc64/fenv.c?r=3D1.4#227

 In contrast, the legacy BSD fpsetround() in libc does set
 _softfloat_float_rounding_mode:

      26 fp_rnd
      27 fpsetround(fp_rnd rnd_dir)
      28 {
      29 	fp_rnd old;
      30 	fp_rnd new;
      31=20
      32 	__asm("st %%fsr,%0" : "=3Dm" (*&old));
      33=20
      34 #ifdef SOFTFLOATSPARC64_FOR_GCC
 =3D>   35 	_softfloat_float_rounding_mode =3D rnd_dir;
      36 #endif
      37=20
      38 	new =3D old;
      39 	new &=3D ~(0x03U << 30);
      40 	new |=3D ((rnd_dir & 0x03U) << 30);
      41=20
      42 	__asm("ld %0,%%fsr" : : "m" (*&new));
      43=20
      44 	return ((uint32_t)old >> 30) & 0x03;
      45 }

 https://nxr.netbsd.org/xref/src/lib/libc/arch/sparc64/gen/fpsetround.c?r=3D=
 1.9#35

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