This series of patches fix PR61441. This patch avoids various transformations
with signaling NaN operands when flag_signaling_nans is on, to avoid folding
which would lose exceptions.

Bootstrapped & regression-tested on x86_64-linux-gnu.

gcc/
	* fold-const.c (const_binop): Convert sNaN to qNaN when
	flag_signaling_nans is off.
	(const_unop): Avoid the operation, other than NEGATE and
	ABS, if flag_signaling_nans is on and the operand is an sNaN.
	(fold_convert_const_real_from_real): Avoid the operation if
	flag_signaling_nans is on and the operand is an sNaN.
	(integer_valued_real_unary_p): Update comment stating it
	returns false for sNaN values.
	(integer_valued_real_binary_p, integer_valued_real_call_p): Same.
	(integer_valued_real_single_p): Same.
	(integer_valued_real_invalid_p, integer_valued_real_p): Same.
	* fold-const-call.c (fold_const_pow): Avoid the operation
	if flag_signaling_nans is on and the operand is an sNaN.
	(fold_const_builtin_load_exponent) Same.
	(fold_const_call_sss): Same for CASE_CFN_POWI.
	* gimple-fold.c (gimple_assign_integer_valued_real_p): Same.
	(gimple_call_integer_valued_real_p): Same.
	(gimple_phi_integer_valued_real_p): Same.
	(gimple_stmt_integer_valued_real_p): Same.
	* simplify-rtx.c (simplify_const_unary_operation): Avoid the
	operation if flag_signaling_nans is on and the operand is an sNaN.
	(simplify_const_binary_operation): Same.
	* tree-ssa-math-opts.c (gimple_expand_builtin_pow): Avoid the
	operation if flag_signaling_nans is on and the operand is an sNaN.

	* gcc.dg/pr61441.c: New testcase.

From-SVN: r231901