cvs commit: src/lib/msun/src s_cbrtf.c

[Bruce Evans]

bde         2006-01-05 09:18:48 UTC

  FreeBSD src repository

  Modified files:
    lib/msun/src         s_cbrtf.c 
  Log:
  Oops, on amd64 (and probably on all non-i386 systems), the previous
  commit broke the 2**24 cases where |x| > DBL_MAX/2.  There are exponent
  range problems not just for denormals (underflow) but for large values
  (overflow).  Doubles have more than enough exponent range to avoid the
  problems, but I forgot to convert enough terms to double, so there was
  an x+x term which was sometimes evaluated in float precision.
  
  Unfortunately, this is a pessimization with some combinations of systems
  and compilers (it makes no difference on Athlon XP's, but on Athlon64's
  it gives a 5% pessimization with gcc-3.4 but not with gcc-3.3).
  
  Exlain the problem better in comments.
  
  Revision  Changes    Path
  1.16      +11 -6     src/lib/msun/src/s_cbrtf.c