Getting illegal memory error when trying to

[Ewicko]

Describe the bug
A clear and concise description of what the bug is, ideally within 20 words.

To Reproduce
Please post a minimal sample code to reproduce the bug.
The developer team will put a higher priority on bugs that can be reproduced within 20 lines of code. If you want a prompt reply, please keep the sample code short and representative.

# sample code here

Log/Screenshots
Please post the full log of the program (instead of just a few lines around the error message, unless the log is > 1000 lines). This will help us diagnose what's happening. For example:

$ python my_sample_code.py
[Taichi] mode=release
[Taichi] version 0.6.29, llvm 10.0.0, commit b63f6663, linux, python 3.8.3
...

Additional comments
If possible, please also consider attaching the output of command ti diagnose. This produces the detailed environment information and hopefully helps us diagnose faster.

If you have local commits (e.g. compile fixes before you reproduce the bug), please make sure you first make a PR to fix the build errors and then report the bug.