The dbl-64, ldbl-96 and ldbl-128 implementations of lrint and llrint
fail to produce "invalid" exceptions in cases where the rounded result
overflows the target type, but truncating the floating-point argument
to the next integer towards zero does not overflow it (so in
particular casts do not produce such exceptions). (This issue cannot
arise for float, or for double with 64-bit target type, or for ldbl-96
with 64-bit target type and negative arguments, because of
insufficient precision in the floating-point type for arguments with
the relevant property to exist. It also obviously cannot arise in
FE_TOWARDZERO mode.)
This patch fixes these problems by inserting checks for the special
cases that can occur in each implementation, and explicitly raising
FE_INVALID (and avoiding the cast if it might raise spurious
FE_INEXACT, while raising FE_INEXACT explicitly in the cases where it
is needed; unlike lround and llround, FE_INEXACT is required, not
optional, for these functions for a within-range inexact result).
The fixes are conditional on FE_INVALID or FE_INEXACT being defined.
If any future architecture supports one but not both of those
exceptions, the code will fail to compile and need fixing to handle
that case (this seemed better than conditioning on both macros being
defined, resulting in code that would compile but quietly miss
exceptions on such a system).
Tested for x86_64, x86 and mips64. Tested the ldbl-96 changes (only
relevant for ia64, it appears) on x86_64 by removing the x86_64
versions of lrintl / llrintl.
[BZ #19094]
* sysdeps/ieee754/dbl-64/s_lrint.c: Include <fenv.h> and
<limits.h>.
(__lrint) [FE_INVALID || FE_INEXACT]: Force FE_INVALID exception
when result overflows but exception would not result from cast.
* sysdeps/ieee754/ldbl-128/s_llrintl.c: Include <fenv.h> and
<limits.h>.
(__llrintl) [FE_INVALID || FE_INEXACT]: Force FE_INVALID exception
when result overflows but exception would not result from cast.
* sysdeps/ieee754/ldbl-128/s_lrintl.c: Include <fenv.h> and
<limits.h>.
(__lrintl) [FE_INVALID || FE_INEXACT]: Force FE_INVALID exception
when result overflows but exception would not result from cast.
* sysdeps/ieee754/ldbl-96/s_llrintl.c: Include <fenv.h> and
<limits.h>.
(__llrintl) [FE_INVALID || FE_INEXACT]: Force FE_INVALID exception
when result overflows but exception would not result from cast.
* sysdeps/ieee754/ldbl-96/s_lrintl.c: Include <fenv.h> and
<limits.h>.
(__lrintl) [FE_INVALID || FE_INEXACT]: Force FE_INVALID exception
when result overflows but exception would not result from cast.
* math/libm-test.inc (lrint_test_data): Add more tests.
(llrint_test_data): Likewise.
Where glibc code needs to avoid excess range and precision in
floating-point arithmetic, code variously uses either asms or volatile
to force the results of that arithmetic to memory; mostly this is
conditional on FLT_EVAL_METHOD, but in the case of lrint / llrint
functions some use of volatile is unconditional (and is present
unnecessarily in versions for long double). This patch make such code
use the recently-added math_narrow_eval macro consistently, removing
the unnecessary uses of volatile in long double lrint / llrint
implementations completely.
Tested for x86_64, x86, mips64 and powerpc.
* math/s_nexttowardf.c (__nexttowardf): Use math_narrow_eval.
* stdlib/strtod_l.c: Include <math_private.h>.
(overflow_value): Use math_narrow_eval.
(underflow_value): Likewise.
* sysdeps/i386/fpu/s_nexttoward.c (__nexttoward): Likewise.
* sysdeps/i386/fpu/s_nexttowardf.c (__nexttowardf): Likewise.
* sysdeps/ieee754/dbl-64/e_gamma_r.c (gamma_positive): Likewise.
(__ieee754_gamma_r): Likewise.
* sysdeps/ieee754/dbl-64/gamma_productf.c (__gamma_productf):
Likewise.
* sysdeps/ieee754/dbl-64/k_rem_pio2.c (__kernel_rem_pio2):
Likewise.
* sysdeps/ieee754/dbl-64/lgamma_neg.c (__lgamma_neg): Likewise.
* sysdeps/ieee754/dbl-64/s_erf.c (__erfc): Likewise.
* sysdeps/ieee754/dbl-64/s_llrint.c (__llrint): Likewise.
* sysdeps/ieee754/dbl-64/s_lrint.c (__lrint): Likewise.
* sysdeps/ieee754/flt-32/e_gammaf_r.c (gammaf_positive): Likewise.
(__ieee754_gammaf_r): Likewise.
* sysdeps/ieee754/flt-32/k_rem_pio2f.c (__kernel_rem_pio2f):
Likewise.
* sysdeps/ieee754/flt-32/lgamma_negf.c (__lgamma_negf): Likewise.
* sysdeps/ieee754/flt-32/s_erff.c (__erfcf): Likewise.
* sysdeps/ieee754/flt-32/s_llrintf.c (__llrintf): Likewise.
* sysdeps/ieee754/flt-32/s_lrintf.c (__lrintf): Likewise.
* sysdeps/ieee754/ldbl-128/s_llrintl.c (__llrintl): Do not use
volatile.
* sysdeps/ieee754/ldbl-128/s_lrintl.c (__lrintl): Likewise.
* sysdeps/ieee754/ldbl-128/s_nexttoward.c (__nexttoward): Use
math_narrow_eval.
* sysdeps/ieee754/ldbl-128ibm/s_nexttoward.c (__nexttoward):
Likewise.
* sysdeps/ieee754/ldbl-128ibm/s_nexttowardf.c (__nexttowardf):
Likewise.
* sysdeps/ieee754/ldbl-96/gamma_product.c (__gamma_product):
Likewise.
* sysdeps/ieee754/ldbl-96/s_llrintl.c (__llrintl): Do not use
volatile.
* sysdeps/ieee754/ldbl-96/s_lrintl.c (__lrintl): Likewise.
* sysdeps/ieee754/ldbl-96/s_nexttoward.c (__nexttoward): Use
math_narrow_eval.
* sysdeps/ieee754/ldbl-96/s_nexttowardf.c (__nexttowardf):
Likewise.
* sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c (__nldbl_nexttowardf):
Likewise.
2006-06-17 Joseph S. Myers <joseph@codesourcery.com>
[BZ #2592]
* math/libm-test.inc (lrint_test_tonearest): New function.
(lrint_test_towardzero): New function.
(lrint_test_downward): New function.
(lrint_test_upward): New function.
(main): Run these new tests.
* sysdeps/ieee754/dbl-64/s_llrint.c (__llrint): Correct rounding
of values near to 0.
(two52): Use double not long double.
* sysdeps/ieee754/dbl-64/s_lrint.c (__lrint): Likewise.
* sysdeps/ieee754/flt-32/s_llrintf.c (__llrintf): Likewise.
(two23): Use float not double.
* sysdeps/ieee754/flt-32/s_lrintf.c (__lrintf): Likewise.
(two23): Use float not double.
* sysdeps/ieee754/ldbl-128/s_llrintl.c (__llrintl): Likewise.
* sysdeps/ieee754/ldbl-128/s_lrintl.c (__lrintl): Likewise.
* sysdeps/ieee754/ldbl-96/s_llrintl.c (__llrintl): Likewise.
* sysdeps/ieee754/ldbl-96/s_lrintl.c (__lrintl): Likewise.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
