PR middle-end/48973
	* expr.c (expand_expr_real_2) <case LT_EXPR>: If do_store_flag
	failed and the comparison has a single bit signed type, use
	constm1_rtx instead of const1_rtx for true value.
	(do_store_flag): If ops->type is single bit signed type, disable
	signel bit test optimization and pass -1 instead of 1 as last
	parameter to emit_store_flag_force.

	* gcc.c-torture/execute/pr48973-1.c: New test.
	* gcc.c-torture/execute/pr48973-2.c: New test.

From-SVN: r174060