optab: Add optab for isnan

Add an optab for isnan.  This requires changes to the existing folding code
to extend the interclass_mathfn infrastructure to support BUILT_IN_ISNAN.
It now checks for a valid optab before emitting the generic expansion.
There is no change if no optab is defined.  Update documentation.

gcc:
	* builtins.cc (interclass_mathfn_icode): Add support for isnan
	optab.
	(expand_builtin): Add BUILT_IN_ISNAN to expand isnan optab.
	(fold_builtin_interclass_mathfn): Expand BUILT_IN_ISNAN only after
	checking for a valid optab.
	(fold_builtin_classify): Move generic BUILT_IN_ISNAN expansion
	to fold_builtin_interclass_mathfn.
	(fold_builtin_1): For BUILT_IN_ISNAN first try fold_builtin_classify,
	then fold_builtin_interclass_mathfn.
	* optabs.def: Add isnan optab.
	* doc/md.texi: Document isnan.

0 files changed, 0 insertions, 0 deletions