[PATCH] Add __builtin_iseqsig()

[Joseph Myers]

My reading of the bug given as a reason for not testing that FE_INVALID is 
raised for (both quiet and signaling) NaN arguments is that it's 
specifically about constant arguments.  That is, it ought to be possible 
to have a testcase that verifies FE_INVALID is raised when appropriate 
(and not when inappropriate) provided the arguments come from volatile 
variables rather than directly from constants.  (There would still need to 
be a powerpc*-*-* XFAIL referencing bug 58684.)  Only a test for constant 
arguments would need to wait on a fix for bug 106805.

-- 
Joseph S. Myers
joseph@codesourcery.com