Summary

Improved the validation of stack top variables in the Sierra to CASM compiler by replacing the UnorderedHashMap with a more efficient vector-based approach. Also replaced zip_eq with standard zip for better compatibility and added a new parameter to validate_stack_top to track stack top size more accurately.

Type of change

Please check one:

• Performance improvement
• Bug fix (fixes incorrect behavior)
• New feature
• Documentation change with concrete technical impact
• Style, wording, formatting, or typo-only change

⚠️ Note:
To keep maintainer workload sustainable, we generally do not accept PRs that
are only minor wording, grammar, formatting, or style changes.
Such PRs may be closed without detailed review.

Why is this change needed?

The current implementation uses an UnorderedHashMap to track stack top variables, which is less efficient than a direct vector-based approach. This change optimizes the validation process by using a vector with direct indexing instead of hash map lookups, improving performance in the Sierra to CASM compilation process.

What was the behavior or documentation before?

Previously, the code used an UnorderedHashMap to track stack top variables and relied on zip_eq for strict iteration, which could be unnecessarily restrictive in some cases.

What is the behavior or documentation after?

Now the code uses a more efficient vector-based approach to track stack top variables, with direct indexing instead of hash map lookups. It also uses standard zip instead of zip_eq for better compatibility, and tracks stack top size more accurately with an explicit parameter.

Additional context

This change is part of ongoing efforts to optimize the Sierra to CASM compilation process, which is a critical part of the Cairo compiler pipeline.