* Makefile.in: rtlanal.o now depends upon real.h.

	* flags.h [flag_signaling_nans]: New flag.
	[HONOR_SNANS]: New macro.

	* toplev.c [flag_signaling_nans]: Initialize to false.
        (f_options): Add processing for "-fsignaling-nans".
	(set_fast_math_flags): Clear flag_signaling_nans with -ffast-math.
	(process_options): flag_signaling_nans implies flag_trapping_math.

	* c-common.c (cb_register_builtins): Define __SUPPORT_SNAN__
	when -fsignaling-nans.  First step to implementing WG14's N965.

	* fold-const.c (fold) [MULT_EXPR]: Conditionalize transforming
	1.0 * x into x, and -1.0 * x into -x on !HONOR_SNANS.
	[RDIV_EXPR]: Conditionalize x/1.0 into x on !HONOR_SNANS.

	* simplify-rtx.c (simplify_relational_operation): Conditionalize
	transforming abs(x) < 0.0 into false on !HONOR_SNANS.

	* rtlanal.c: #include real.c for TARGET_FLOAT_FORMAT definitions
	required by HONOR_SNANS.  (may_trap_p): Floating point DIV, MOD,
	UDIV, UMOD, GE, GT, LE, LT and COMPARE may always trap with
	-fsignaling_nans.  EQ and NE only trap for flag_signaling_nans
	not flag_trapping_math (i.e. HONOR_SNANS but not HONOR_NANS).

	* doc/invoke.texi: Document new -fsignaling-nans compiler option.

From-SVN: r55804