* config/i386/i386.md (UNSPEC_FPATAN): New UNSPEC constant.
	(atan2sf3, atan2df3, atan2xf3, atan2tf3): New patterns.

	* reg-stack.c (subst_stack_regs_pat): Add support for binary
	UNSPEC instructions (e.g. "fpatan").

	* gcc.dg/i386-387-1.c: Add new test for __builtin_atan2.
	* gcc.dg/i386-387-2.c: Likewise.

From-SVN: r62816