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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2022-10-13 11:10:10 +0100 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2022-10-17 08:18:52 +0100 |
| commit | 7363a9a9a097c455a7ddb9386b4c6f7bdf91065f (patch) | |
| tree | 8e11dcf8264bf1760830c82a0c086e828d8cab8b | |
| parent | be066536bd313f1eec6e36fb92a96d39bf76f483 (diff) | |
| download | glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.zip glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.tar.gz glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.tar.bz2 | |
math: Fix asin and acos invalid exception with old gcc
This works around a gcc issue where it const folded inf/inf into nan,
preventing the invalid exception to be signalled.
(x-x)/(x-x) is more robust against optimizations and works for all
out of bounds values including x==nan.
The gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95115
should be fixed on release branches starting from gcc-10, but it is
better to change the code in case glibc is built with older gcc.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
| -rw-r--r-- | sysdeps/ieee754/dbl-64/e_asin.c | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_asin.c b/sysdeps/ieee754/dbl-64/e_asin.c index e7ea0cb..6b7c971 100644 --- a/sysdeps/ieee754/dbl-64/e_asin.c +++ b/sysdeps/ieee754/dbl-64/e_asin.c @@ -165,14 +165,7 @@ __ieee754_asin(double x){ /*---------------------------- |x|>=1 -------------------------------*/ else if (k==0x3ff00000 && u.i[LOW_HALF]==0) return (m>0)?hp0.x:-hp0.x; else - if (k>0x7ff00000 || (k == 0x7ff00000 && u.i[LOW_HALF] != 0)) return x + x; - else { - u.i[HIGH_HALF]=0x7ff00000; - v.i[HIGH_HALF]=0x7ff00000; - u.i[LOW_HALF]=0; - v.i[LOW_HALF]=0; - return u.x/v.x; /* NaN */ - } + return (x - x) / (x - x); } #ifndef __ieee754_asin libm_alias_finite (__ieee754_asin, __asin) @@ -334,14 +327,7 @@ __ieee754_acos(double x) else if (k==0x3ff00000 && u.i[LOW_HALF]==0) return (m>0)?0:2.0*hp0.x; else - if (k>0x7ff00000 || (k == 0x7ff00000 && u.i[LOW_HALF] != 0)) return x + x; - else { - u.i[HIGH_HALF]=0x7ff00000; - v.i[HIGH_HALF]=0x7ff00000; - u.i[LOW_HALF]=0; - v.i[LOW_HALF]=0; - return u.x/v.x; - } + return (x - x) / (x - x); } #ifndef __ieee754_acos libm_alias_finite (__ieee754_acos, __acos) |