Fix compilation slowdown due to controlflow analysis - #6146

from pprint import pprint
import numpy as np
import numba

body = """
    for fi in range(0, 10):
        data[fi] += 1
        for index in range(0, 7):
            idx = index
            if idx % 2 == 0:
                data[idx] += fi
            else:
                data[idx] += 1 if data[idx] < 3 else 2
                data[idx] += 1
            data[idx] += 1
"""

wrapper = """
def kernel(data):
    {}
"""

source = wrapper.format(body * 100) # 75
glbs = {}
exec(source, glbs)

arg = np.zeros(100)
argtypes = (numba.typeof(arg),)

kernel = numba.njit(argtypes)(glbs['kernel'])

# 0.48.0 takes 24sec
# 0.51.0 takes 1min13sec

metadata = kernel.get_metadata(kernel.signatures[0])
timings = metadata['pipeline_times']['nopython']
sorttimings = sorted(timings.items(), key=lambda x: sum(x[1]))
for k, v in reversed(sorttimings):
    print(f"{k:40} {sum(v):.3}")