fix bound type mismatch for compares and document other fallthrough cases
fix bound type mismatch for compares and document other fallthrough cases


Former-commit-id: f3253ce50bcb201c2569fe1fd5ee670aab375205
Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide