PR tree-optimization/57124
	* tree-vrp.c (simplify_cond_using_ranges): Only simplify a
	conversion feeding a condition if the range has an overflow
	if -fstrict-overflow.  Add warnings for when we do make the
	transformation.

	PR tree-optimization/57124
	* gcc.c-torture/execute/pr57124.c: New test.
	* gcc.c-torture/execute/pr57124.x: Set -fno-strict-overflow.

From-SVN: r199305