* builtins.def (BUILT_IN_SIGNBIT, BUILT_IN_SIGNBITF,
BUILT_IN_SIGNBITL): New GCC builtins.
* builtins.c (expand_builtin_signbit): New function to RTL expand
calls to signbit, signbitf and signbitl as inline intrinsics.
(expand_builtin): Call expand_builtin_signbit for BUILT_IN_SIGNBIT*.
(fold_builtin_signbit): New function to perform constant folding
of signbit, signbitf and signbitl.
(fold_builtin): Call fold_builtin_signbit for BUILT_IN_SIGNBIT*.
* doc/extend.texi: Document new signbit{,f,l} builtins.
* gcc.dg/builtins-1.c: Also test for __builtin_signbit{,f,l}.
* gcc.dg/builtins-31.c: New testcase.
* gcc.dg/builtins-32.c: New testcase.
From-SVN: r77070
