aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/ieee754
diff options
context:
space:
mode:
authorSzabolcs Nagy <szabolcs.nagy@arm.com>2022-10-13 11:10:10 +0100
committerSzabolcs Nagy <szabolcs.nagy@arm.com>2022-10-17 08:18:52 +0100
commit7363a9a9a097c455a7ddb9386b4c6f7bdf91065f (patch)
tree8e11dcf8264bf1760830c82a0c086e828d8cab8b /sysdeps/ieee754
parentbe066536bd313f1eec6e36fb92a96d39bf76f483 (diff)
downloadglibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.tar
glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.tar.gz
glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.tar.bz2
glibc-7363a9a9a097c455a7ddb9386b4c6f7bdf91065f.zip
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>
Diffstat (limited to 'sysdeps/ieee754')
-rw-r--r--sysdeps/ieee754/dbl-64/e_asin.c18
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 e7ea0cbe8f..6b7c971e76 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)