Raise CPI Nesting Limit

Summary

Increase the maximum number of nested CPI calls.

Motivation

The complexity of dApp interoperation is limited by how many programs can call into one another.

New Terminology

None.

Detailed Design

Once the associated feature gate is activated the maximum nesting depth of CPI calls must be changed from 4 to 8. This feature should only be activated after SIMD-0219.

Alternatives Considered

None.

Impact

Exisiting dApps will not be affected as long as they don't depend on this limit in their logic to fail transactions, which is unlikely.

Security Considerations

None.

Drawbacks

The maximum amount of VMs stack and heap memory, which needs to be reserved and zeroed out, would double.