bug: Cairo runner does not support array arguments larger than 2^15

[m-kus]

Bug Report

Cairo version:

737cc88

Current behavior:

When running a program with an array argument that is of length 32768:

• In debug mode: Cairo runner fails with overflow when tries to increment the allocation pointer while loading arguments;
• In release mode: Cairo runner loads arguments without errors postponing the memory issue to the cairo-vm execution.

Expected behavior:

Cairo runner works without errors in both debug and release, there are no memory issues during the cairo-vm execution.

Steps to reproduce:

Unit test:
https://github.com/m-kus/cairo/pull/1/files

Related code:

The minimal program to reproduce the issue:

fn main(args: Array<felt252>) {}

Other information:

Possibly related:

• CairoVM runner is not checking Relocatable offset i16 overflow during runtime lambdaclass/cairo-vm#1848 (comment)
• [Cairo 1] Load arguments into VM instead of creating them via instructions lambdaclass/cairo-vm#1759

[maciejka]

When the arg size is large the ap_offset that is tracking ap overflows here:

cairo/crates/cairo-lang-runner/src/lib.rs

Line 864 in 737cc88

*ap_offset += 1;

.

[orizi]

This should be done as part of lambdaclass/cairo-vm#1759 - as the issue is the amount of instructions created for this explicit array creation.

Is going to be solved at the future when the code isn't actually changing by the specific inputs it received.

In the near future we should have a way of running code, where the input is always a Span of felts and the output is always a Span of felts, where both are directly deserialized (from the inputs) and serialized (into the output builtin) providing a provable method of run.

So basically - it isn't a bug - as this was just for local purposes (as cairo-run didn't actually run anything provable, so i would have expected it to work) - but the missing feature should exist soon enough.