port-mips/59284: pmax testbed rounding modes are broken

[campbell+netbsd%mumble.net@localhost]

>Number:         59284
>Category:       port-mips
>Synopsis:       pmax testbed rounding modes are broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-mips-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Apr 12 17:45:00 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The PmaxBSD Roundation
>Environment:
>Description:
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:163: y1 != z1: FE_TOWARDZERO[-1 + ulp(1)/4] expected=-0x1p+0 actual=-0x1.fffffffffffffp-1
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:165: y2 != z2: FE_TOWARDZERO[1 + 3*(ulp(1)/2)] expected=0x1.0000000000002p+0 actual=0x1.0000000000001p+0
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:165: y2 != z2: FE_DOWNWARD[1 + 3*(ulp(1)/2)] expected=0x1.0000000000002p+0 actual=0x1.0000000000001p+0
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:163: y1 != z1: FE_UPWARD[-1 + ulp(1)/4] expected=-0x1p+0 actual=-0x1.fffffffffffffp-1

https://releng.netbsd.org/b5reports/pmax/2025/2025.04.11.04.54.02/test.html#lib_libm_t_fenv_fegetround

*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:163: y1 != z1: FE_TOWARDZERO[-1 + ulp(1)/4] expected=-0x1p+0 actual=-0x1.fffffffffffffp-1
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:165: y2 != z2: FE_TOWARDZERO[1 + 3*(ulp(1)/2)] expected=0x1.0000000000002p+0 actual=0x1.0000000000001p+0
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:165: y2 != z2: FE_DOWNWARD[1 + 3*(ulp(1)/2)] expected=0x1.0000000000002p+0 actual=0x1.0000000000001p+0
*** Check failed: /tmp/build/2025.04.11.04.54.02-pmax/src/tests/lib/libm/t_fenv.c:163: y1 != z1: FE_UPWARD[-1 + ulp(1)/4] expected=-0x1p+0 actual=-0x1.fffffffffffffp-1

https://releng.netbsd.org/b5reports/pmax/2025/2025.04.11.04.54.02/test.html#lib_libm_t_fenv_fesetround
>How-To-Repeat:
cd /usr/tests/lib/libm
atf-run t_fenv t_fe_round | atf-report
>Fix:
Yes, please!

Not sure if this is a qemu bug or a hardware bug or a NetBSD kernel bug in configuring the FPU.  Guessing it's probably a qemu bug and might be helped by adding if (isQEMU()) { atf_tc_expect_fail("PR ...") }.