* optabs.h (enum optab_index): Add new OTI_scalb.
	(scalb_optab): Define corresponding macro.
	* optabs.c (init_optabs): Initialize scalb_optab.
	* genopinit.c (optabs): Implement scalb_optab using scalb?f3
	patterns.
	* builtins.c (expand_builtin_mathfn_2, expand_builtin): Handle
	BUILT_IN_SCALB{,F,L}, BUILT_IN_SCALBN{,F,L} and BUILT_IN_SCALBLN{,F,L}.
	(expand_builtin): Expand BUILT_IN_SCALB{,F,L}, BUILT_IN_SCALBN{,F,L}
	and BUILT_IN_SCALBLN{,F,L} using expand_builtin_mathfn_2 if
	flag_unsafe_math_optimizations is set.

	* config/i386/i386.md (scalbxf3, scalb<mode>3): New expanders
	to implement scalbf, scalb and scalbl built-ins as inline x87
	intrinsics.

testsuite/ChangeLog

	* gcc.dg/builtins-34.c: Add scalb/scalbn/scalbln cases.

From-SVN: r122162