http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52593
--- Comment #7 from Rich Felker <bugdal at aerifal dot cx> 2012-04-28 23:21:51 UTC --- This bug seems to have been fixed with the addition of the -fexcess-precision=standard feature, which is now set by default with -std=c99 or c11, and which disables the builtin sqrt based on 387 fsqrt. So apparently it had already been fixed at the time I reported this, but I was unaware of the right options to enable the fix and did not even think to try just using -std=c99. Note that for buggy libm (including glibc's), the fact that gcc has fixed the issue will not fix the incorrect results, since the code in libm makes exactly the same mistake gcc was making. But at least it's possible to fix it there.
