[Bug middle-end/35509] [4.3/4.4 Regression] builtin isinf() mismatch to compile-time substitution

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-03-08 10:52 -------
Note that one might argue that the testcase is invalid as as you say, C99 only
says isinf returns non-zero.  So strictly speaking comparing the return value
of two invocations is not a way to check if both values are an infinity.

Of course this is at least an QOI issue.  The question is what behavior to
retain?  The glibc manpage documents returning -1 for -Inf and +1 for +Inf,
which we could preserve on glibc targets then not expanding via
isgreater(fabs(x),DBL_MAX).

(Only i386 and s390 have target dependent expansions for isinf - what is
their behavior here?)

Kaveh, you introduced the generic fallback, Andreas, what does s390 return
here, Uros, how is the situation on i386?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ghazi at gcc dot gnu dot
                   |                            |org, uros at gcc dot gnu dot
                   |                            |org, rguenth at gcc dot gnu
                   |                            |dot org, krebbel at gcc dot
                   |                            |gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35509