Wrong results when using `hcl.cast` to convert `hcl.Int` to `hcl.Fixed`

I'm using the hcl-mlir branch and want to convert the arbitrary integer data to fixed point data. In some test cases, I got the wrong results which are not due to the precision loss.

import heterocl as hcl
import numpy as np

# in_dtype, out_dtype = hcl.Int(8), hcl.Fixed(16, 8) # failed
# in_dtype, out_dtype = hcl.Int(8), hcl.Int(32) # succeed
# in_dtype, out_dtype = hcl.Int(6), hcl.Int(8) # succeed
# in_dtype, out_dtype = hcl.Int(6), hcl.Fixed(16, 8) # failed

for in_precision in range(6, 33, 2):
    for out_precision in range(8, 33, 2):
        in_dtype, out_dtype = hcl.Int(in_precision), hcl.Fixed(out_precision, int(out_precision/2))
        def cast(A):
            return hcl.compute(A.shape, lambda *args: hcl.cast(out_dtype, A[args]), "cast", dtype=out_dtype)

        A = hcl.placeholder((1, 10), "A", dtype=in_dtype)
        s = hcl.create_schedule([A], cast)
        f = hcl.build(s)

        a_np = np.random.randint(0, 5, A.shape)
        a = hcl.asarray(a_np, dtype=in_dtype)
        c = hcl.asarray(np.zeros(A.shape), dtype=out_dtype)

        try:
            f(a, c)
        except Exception as e:
            print("{} -> {} failed: {}".format(in_dtype, out_dtype, e), flush=True)
        else:
            c_np = c.asnumpy()
            if (a_np == c_np).all():
                print("{} -> {} succeeded.".format(in_dtype, out_dtype), flush=True)
            else:
                print("{} -> {} failed, wrong result value".format(in_dtype, out_dtype), flush=True)
                print("a_np: ", a_np)
                print("c_np: ", c_np)

For example,

Int(8) -> Fixed(12, 6) failed, wrong result value
a_np:  [[3 4 2 2 3 2 4 2 2 1]]
c_np:  [[-1.  0. -2. -2. -1. -2.  0. -2. -2.  1.]]

Please help check the problem.

cornell-zhang / heterocl

Wrong results when using `hcl.cast` to convert `hcl.Int` to `hcl.Fixed` #475