reg-stack.c (subst_stack_regs_pat): Use generic code for instructions that operate on the top of stack.

	* reg-stack.c (subst_stack_regs_pat) [UNSPEC_SINCOS_COS,
	UNSPEC_XTRACT_FRACT]: Use generic code for instructions that
	operate on the top of stack.
	[UNSPEC_SINCOS_SIN, UNSPEC_XTRACT_EXP, UNSPEC_TAN]: Rewrite
	register handling of instructions that output to the second
	stack slot.
	[UNSPEC_TAN_ONE, UNSPEC_TAN_TAN]: Remove.
	(move_for_stack_reg): Special-case check for dead destination
	stack slot for constant load of 1.0 inside UNSPEC_TAN.

	* config/i386/i386.md (UNSPEC_TAN): New constant.
	(UNSPEC_TAN_ONE, UNSPEC_TAN_TAN): Remove.
	(fptanxf4_i387, fptan_extend<mode>xf4_i387): New patterns
	to correctly model move of constant 1.0 to top stack slot.
	(*tandf3_1, *tansf3_1, *tanxf3_1): Remove insn patterns.
	(unnamed peephole2 pattern): Remove corresponding peephole2
	pattern that optimizes tan insn and loading of constant 1.0.
	(tanxf2): Use fptanxf4_i387.
	(tan<mode>2): Rename from tansf2 and tandf2 and macroize insn
	patterns using X87MODEF12 mode macro.  Use fptan_extend<mode>xf4_i387
	and truncate result to requested mode.  Use SSE_FLOAT_MODE_P to
	disable patterns for SSE math.
	(sincos<mode>3): Use truncxf<mode>2_i387_noop for truncation.
	(fyl2x_extend<mode>xf3_i387): Use X87MODEF12 for operand 1.

testsuite/ChangeLog:

	* gcc.target/i386/387-8.c: Update comment about optimizing
	inherent load of 1.0 of fptan instruction.

From-SVN: r120899