Pledge(2) like utility for odb

[QuantamHD]

Description

Add a utility to OpenROAD that lets pass authors pledge away certain operations during their code execution. If a pass performs an operation that it pledged not to odb would throw an error. Which would help prevent bugs like #6289

Suggested Solution

These pledges are similar in nature to the FreeBSD pledge(2) syscall that lets process restrict the syscalls they can make as a security feature.

Ideally we would have some built-in mechanism to odb to pledge away write/delete operations on certain objects. Potentially, using RAII to undo them automatically.

Additional Context

https://man.openbsd.org/pledge.2

[maliberty]

Wouldn't a temporary dont-touch be equivalent? With only the one example I'm not sure what operations/semantics need pledging.

[QuantamHD]

But you would have to set that on each net of those types. This would essentially be a global precheck.

[maliberty]

Would you illustrate with some examples where this works be helpful?