Using circuit.bits as args to add_wasm with more registers causes a Fatal Python error.

[johnchildren]

Using a test case like this in test_classical.py

def test_wasm_circuit_bits() -> None:
    w = wasm.WasmFileHandler("testfile.wasm")
    c = Circuit(0, 6)
    c.add_wasm("add_one", w, [1], [1], c.bits)
    assert c.depth() == 1

Results in an error during the tests of:

classical_test.py ................[2024-10-29 15:13:09] [tket] [critical] Assertion 'sum_of_i32 == n_' (/build/tket-sources/src/Ops/ClassicalOps.cpp : WASMOp : 266) failed>
Fatal Python error: Aborted

Current thread 0x00007ffff7f8f740 (most recent call first):
  File "/nix/store/sldmq9pa6aw0plb54q6lc9maydx6a35k-python3.12-pytket-1.34.0/lib/python3.12/site-packages/pytket/circuit/__init__.py", line 103 in overload_add_wasm
  File "/build/test_root/tests/classical_test.py", line 363 in test_wasm_circuit_bits

Not that reducing the number of classical registers in the circuit or using a different args avoids this issue.

[johnchildren]

You can also trigger this bug with:

def test_wasm_circuit_bits() -> None:
    w = wasm.WasmFileHandler("testfile.wasm")
    c = Circuit(0, 1)
    c.add_wasm("add_one", w, [1], [1], [0])
    assert c.depth() == 1

[cqc-alec]

I noticed recently that the unit ID we use for the wasm state (which has the special name _w) has type Bit, which seems wrong. Could this be related @cqc-melf ?

[cqc-melf]

@cqc-alec I have taken a look on this, it should have the type WasmState, see

tket/tket/include/tket/Utils/UnitID.hpp

Line 229 in a9add4b

class WasmState : public UnitID {

Can you give some more details where you have seen this? I was not able to construct an example where this did not work.

[cqc-alec]

@cqc-alec I have taken a look on this, it should have the type WasmState, see

tket/tket/include/tket/Utils/UnitID.hpp

Line 229 in a9add4b
class WasmState : public UnitID {

Can you give some more details where you have seen this? I was not able to construct an example where this did not work.

In this test, if you insert the lines

    cmd = c.get_commands()[0]
    for arg in cmd.args:
        print(arg, type(arg))

after constructing the circuit, and run it with pytest -s, you see:

c[0] <class 'pytket._tket.unit_id.Bit'>
c[1] <class 'pytket._tket.unit_id.Bit'>
_w[0] <class 'pytket._tket.unit_id.Bit'>

(This was the reason for this workaround.)

[johnchildren]

Is the issue that there is no python binding for the WasmState class? Should it even have a python binding?

[cqc-melf]

Is the issue that there is no python binding for the WasmState class? Should it even have a python binding?

Probably yes, still unexpected that they show up as bits. I will add them.

[cqc-melf]

@cqc-alec I have taken a look on this, it should have the type WasmState, see
tket/tket/include/tket/Utils/UnitID.hpp
Line 229 in a9add4b
class WasmState : public UnitID {
Can you give some more details where you have seen this? I was not able to construct an example where this did not work.

In this test, if you insert the lines

cmd = c.get_commands()[0]
for arg in cmd.args:
    print(arg, type(arg))

after constructing the circuit, and run it with pytest -s, you see:

c[0] <class 'pytket._tket.unit_id.Bit'>
c[1] <class 'pytket._tket.unit_id.Bit'>
_w[0] <class 'pytket._tket.unit_id.Bit'>

(This was the reason for this workaround.)

Thank you! I will solves this together with the other issues.