Similar to various other bugs in this area, hypot functions can fail
to raise the underflow exception when the result is tiny and inexact
but one or more low bits of the intermediate result that is scaled
down (or, in the i386 case, converted from a wider evaluation format)
are zero. This patch forces the exception in a similar way to
previous fixes.
Note that this issue cannot arise for implementations of hypotf using
double (or wider) for intermediate evaluation (if hypotf should
underflow, that means the double square root is being computed of some
number of the form N*2^-298, for 0 < N < 2^46, which is exactly
represented as a double, and whatever the rounding mode such a square
root cannot have a mantissa with all zeroes after the initial 23
bits). Thus no changes are made to hypotf implementations in this
patch, only to hypot and hypotl.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #18803]
* sysdeps/i386/fpu/e_hypot.S: Use DEFINE_DBL_MIN.
(MO): New macro.
(__ieee754_hypot) [PIC]: Load PIC register.
(__ieee754_hypot): Use DBL_NARROW_EVAL_UFLOW_NONNEG instead of
DBL_NARROW_EVAL.
* sysdeps/ieee754/dbl-64/e_hypot.c (__ieee754_hypot): Use
math_check_force_underflow_nonneg in case where result might be
tiny.
* sysdeps/ieee754/ldbl-128/e_hypotl.c (__ieee754_hypotl):
Likewise.
* sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl):
Likewise.
* sysdeps/ieee754/ldbl-96/e_hypotl.c (__ieee754_hypotl): Likewise.
* sysdeps/powerpc/fpu/e_hypot.c (__ieee754_hypot): Likewise.
* math/auto-libm-test-in: Add more tests of hypot.
* math/auto-libm-test-out: Regenerated.
i386 exp, hypot and pow functions can return overflowing and
underflowing values with excess range and precision; ; Wilco
Dijkstra's patches to make isfinite etc. expand inline cause this
pre-existing issue to result in test failures.
This patch fixes those functions to avoid excess range and precision
in their return values. Appropriate macros are added for the repeated
code sequences; in future I'll add more such macros and refactor
existing code forcing underflow (with or without also eliminating
excess range and precision from the return value) to use such macros.
Tested for x86. If, after this patch, you still see x86 libm test
failures with excess range or precision, please file bugs in Bugzilla.
[BZ #18980]
* sysdeps/i386/fpu/i386-math-asm.h (DEFINE_FLT_MIN): New macro.
(DEFINE_DBL_MIN): Likewise.
(FLT_NARROW_EVAL_UFLOW_NONNEG_NAN): Likewise.
(DBL_NARROW_EVAL_UFLOW_NONNEG_NAN): Likewise.
(FLT_NARROW_EVAL_UFLOW_NONNEG): Likewise.
(DBL_NARROW_EVAL_UFLOW_NONNEG): Likewise.
* sysdeps/i386/fpu/e_exp.S: Include <i386-math-asm.h>.
(dbl_min): Replace with use of DEFINE_DBL_MIN.
(__ieee754_exp): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
(__exp_finite): Use DBL_NARROW_EVAL_UFLOW_NONNEG.
* sysdeps/i386/fpu/e_exp10.S: Include <i386-math-asm.h>.
(dbl_min): Replace with use of DEFINE_DBL_MIN.
(__ieee754_exp10): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
* sysdeps/i386/fpu/e_exp10f.S: Include <i386-math-asm.h>.
(flt_min): Replace with use of DEFINE_FLT_MIN.
(__ieee754_exp10f): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
* sysdeps/i386/fpu/e_exp2.S: Include <i386-math-asm.h>.
(dbl_min): Replace with use of DEFINE_DBL_MIN.
(__ieee754_exp2): Use DBL_NARROW_EVAL_UFLOW_NONNEG_NAN.
* sysdeps/i386/fpu/e_exp2f.S: Include <i386-math-asm.h>.
(flt_min): Replace with use of DEFINE_FLT_MIN.
(__ieee754_exp2f): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
* sysdeps/i386/fpu/e_expf.S: Include <i386-math-asm.h>.
(flt_min): Replace with use of DEFINE_FLT_MIN.
(__ieee754_expf): Use FLT_NARROW_EVAL_UFLOW_NONNEG_NAN.
(__expf_finite): Use FLT_NARROW_EVAL_UFLOW_NONNEG.
* sysdeps/i386/fpu/e_hypot.S: Include <i386-math-asm.h>.
(__ieee754_hypot): Use DBL_NARROW_EVAL.
* sysdeps/i386/fpu/e_hypotf.S: Include <i386-math-asm.h>.
(__ieee754_hypotf): Use FLT_NARROW_EVAL.
* sysdeps/i386/fpu/e_pow.S: Include <i386-math-asm.h>.
(__ieee754_pow): Use DBL_NARROW_EVAL.
* sysdeps/i386/fpu/e_powf.S: Include <i386-math-asm.h>.
(__ieee754_powf): Use FLT_NARROW_EVAL.
* sysdeps/i386/i686/fpu/multiarch/e_expf-sse2.S
(__ieee754_expf_sse2): Convert double-precision result to single
precision.
* sysdeps/i386/fpu/libm-test-ulps: Update.
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.
