Testable Device-Side Assertion Failures on CPUs

[xumingkuan]

Related issue id = #591

A continuation of #582

[xumingkuan]

Test case:

ti.init(debug=True)

@ti.kernel
def boom():
  assert 0

boom()

Output:

error code: 0000000000000000
<some debug printf's in `taichi_assert_runtime`>

Are we checking the error code too early?

[yuanming-hu]

(Note that when two threads use printf simultaneously, there's no guarantee their outputs will be sorted according to wall clock time.)

[xumingkuan]

I got this in another run:

error code in taichi_assert_runtime: 1
error code: 0000000000000000

Go to sleep now. Maybe debug it tomorrow.

[yuanming-hu]

I'm actually slightly confused: why error code: 0000000000000000 instead of error code: 0?

[xumingkuan]

std::cout << "i64 " << (typeid(error_code) == typeid(unsigned long long)) << std::endl;
std::cout << "u64 " << (typeid(error_code) == typeid(long long)) << std::endl;
std::cout << "ptr " << (typeid(error_code) == typeid(void *)) << std::endl;
std::cout << "error code: " << error_code << std::endl;

Output:

i64 0
u64 0
ptr 1
error code: 0000000000000000

[yuanming-hu]

Oh I see. You are printing a pointer.

[xumingkuan]

auto error_code = runtime_jit_module->fetch_result<long long>();
By making this change, the output becomes:

error code in taichi_assert_runtime: 1
i64 1
u64 0
ptr 0
error code: 0

[yuanming-hu]

How is this going? Do you need any help? I'm available via Skype if you would like to chat.

[xumingkuan]

Let's Skype chat then.

[yuanming-hu]

Please move ErrorMessage to LLVMRuntime.

[yuanming-hu]

Awesome! Could you please add some unit tests for bound checks and basic assert statements in tests/python/test_assert.py?

[xumingkuan]

The exception raised is RuntimeError but not AssertionError. Maybe AssertionError is only for python assertions?

[yuanming-hu]

The exception raised is RuntimeError but not AssertionError. Maybe AssertionError is only for python assertions?

Yeah, let's just use RuntimeError for it now.

[yuanming-hu]

Need any help on this PR?

[xumingkuan]

Why did CI fail?

[yuanming-hu]

Let me see.

[xumingkuan]

(Unlike AppVeyor, I can't find console log on Travis CI...)

[yuanming-hu]

(Unlike AppVeyor, I can't find console log on Travis CI...)

That's true. But good problem solvers don't find excuses. They look for ways to solve the problems or ask for help from someone more experienced :-)

[xumingkuan]

Go to cook dinner now. I think this is an issue across platforms but I only have access to my Windows laptop. See you later.

[yuanming-hu]

Yeah, it is indeed a cross-platform issue but please let me know next time when you run into something that you can't resolve on your own.

[yuanming-hu]

Should be fixed now. Please rebase your commits on master.

[archibate]

The exception raised is RuntimeError but not AssertionError. Maybe AssertionError is only for python assertions?

std::exception is translated into RuntimeError. See pybind11 doc:exception for more info.

[yuanming-hu]

LGTM!