This patch fixes bug 16287, spurious underflows from ldbl-128 erfl
arising from it calling erfcl for arguments with absolute value at
least 1.0, although for large positive arguments erfcl correctly
underflows but erfl shouldn't. The fix is simply to avoid calling
erfcl, and just return 1, for arguments above a cut-off large enough
that erfl correctly rounds to-nearest as 1 but not so large that erfcl
underflows.
Tested mips64. Also tested x86_64 and x86 to confirm the new tests
(taken from the tests of erfc) don't cause any problems there; no ulps
updates needed.
[BZ #16287]
* sysdeps/ieee754/ldbl-128/s_erfl.c (__erfl): Return 1 without
calling __erfcl for arguments at least 16.
* math/auto-libm-test-in: Add more tests of erf.
* math/auto-libm-test-out: Regenerated.
Bug 16516 reports spurious underflows from erf (for all floating-point
types), when the result is close to underflowing but does not actually
underflow.
erf (x) is about (2/sqrt(pi))*x for x close to 0, so there are
subnormal arguments for which it does not underflow. The various
implementations do (x + efx*x) (for efx = 2/sqrt(pi) - 1), for greater
accuracy than if just using a single multiplication by an
approximation to 2/sqrt(pi) (effectively, this way there are a few
more bits in the approximation to 2/sqrt(pi)). This can introduce
underflows when efx*x underflows even though the final result does
not, so a scaled calculation with 8*efx is done in these cases - but 8
is not a big enough scale factor to avoid all such underflows. 16 is
(any underflows with a scale factor of 16 would only occur when the
final result underflows), so this patch changes the code to use that
factor. Rather than recomputing all the values of the efx8 variable,
it is removed, leaving it to the compiler's constant folding to
compute 16*efx. As such scaling can also lose underflows when the
final scaling down happens to be exact, appropriate checks are added
to ensure underflow exceptions occur when required in such cases.
Tested x86_64 and x86; no ulps updates needed. Also spot-checked for
powerpc32 and mips64 to verify the changes to the ldbl-128ibm and
ldbl-128 implementations.
[BZ #16516]
* sysdeps/ieee754/dbl-64/s_erf.c (efx8): Remove variable.
(__erf): Scale by 16 instead of 8 in potentially underflowing
case. Ensure exception if result actually underflows.
* sysdeps/ieee754/flt-32/s_erff.c (efx8): Remove variable.
(__erff): Scale by 16 instead of 8 in potentially underflowing
case. Ensure exception if result actually underflows.
* sysdeps/ieee754/ldbl-128/s_erfl.c: Include <float.h>.
(efx8): Remove variable.
(__erfl): Scale by 16 instead of 8 in potentially underflowing
case. Ensure exception if result actually underflows.
* sysdeps/ieee754/ldbl-128ibm/s_erfl.c: Include <float.h>.
(efx8): Remove variable.
(__erfl): Scale by 16 instead of 8 in potentially underflowing
case. Ensure exception if result actually underflows.
* sysdeps/ieee754/ldbl-96/s_erfl.c: Include <float.h>.
(efx8): Remove variable.
(__erfl): Scale by 16 instead of 8 in potentially underflowing
case. Ensure exception if result actually underflows.
* math/auto-libm-test-in: Add more tests of erf.
* math/auto-libm-test-out: Regenerated.
2001-09-29 Jes Sorensen <jes@trained-monkey.org>
* sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h (struct sigcontext):
Add sc_loadrs and sc_rbs_bas to match current kernel.
2001-09-27 Jakub Jelinek <jakub@redhat.com>
* sysdeps/sparc/sparc64/fpu/libm-test-ulps: Update.
* sysdeps/ieee754/ldbl-128/s_erfl.c (__erfcl): Fix erfc(-inf).
2001-09-27 Jakub Jelinek <jakub@redhat.com>
* elf/dl-open.c (dl_open_worker): If l_opencount of freshly loaded
object has been bumped because of relocation dependency, avoid
duplicates in l_scope.
(show_scope): Fix typos.
* elf/Makefile: Add rules to build and run reldep6.
* elf/reldep6.c: New file.
* elf/reldep6mod0.c: New file.
* elf/reldep6mod1.c: New file.
* elf/reldep6mod2.c: New file.
* elf/reldep6mod3.c: New file.
* elf/reldep6mod4.c: New file.
2001-09-26 Jakub Jelinek <jakub@redhat.com>
* sysdeps/sparc/sparc64/dl-machine.h (elf_machine_fixup_plt): Call
sparc64_fixup_plt.
(sparc64_fixup_plt): Moved from elf_machine_fixup_plt. Optimize
near jumps and 0xfffff800XXXXXXXX target addresses, no thread safety
for non-lazy binding. Fix .plt[32768+] handling.
(elf_machine_plt_value): Don't add addend.
(elf_machine_rela): Call sparc64_fixup_plt instead of
elf_machine_fixup_plt.
(elf_machine_runtime_setup, TRAMPOLINE_TEMPLATE): Optimize for
dynamic linker at 0xfffff800XXXXXXXX.
* sysdeps/sparc/sparc32/fpu/libm-test-ulps: Update.
