performance(sierra-gas): Smaller equivalent costs map.

[orizi]

Summary

Optimized the rectify method in PreCost implementation by replacing a map-and-max operation with a filter-map approach. Instead of iterating through all values and replacing negative values with zero, the new implementation simply filters out negative values entirely, keeping only non-negative entries in the resulting cost map.

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Type of change

Please check one:

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

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Why is this change needed?

The current implementation of rectify in PreCost iterates through all values and replaces negative values with zero. This is inefficient since we're keeping entries with zero values in the map. The new implementation filters out negative values entirely, which reduces the size of the resulting map and improves performance.

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What was the behavior or documentation before?

Previously, the rectify method would iterate through all entries in the cost map and replace any negative values with zero, keeping all entries in the map.

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What is the behavior or documentation after?

Now, the rectify method filters out any entries with negative values, keeping only entries with non-negative values in the resulting map. This reduces the map size and improves performance.

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Additional context

This change maintains the same functional behavior while making the code more efficient. The Sierra gas computation will produce the same results, but with potentially fewer entries in the cost maps.

[orizi]

Warning

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• performance(sierra-gas): Smaller equivalent costs map. #9535 👈 (View in Graphite)
• performance(sierra-gas): Added unchecked initialization, improving runtime marginally. #9529
• refactor(vec-map): Removed dependency on vec map totally. #9528
• performance(utils): By hand implementation of small-ordered-map. #9527
• performance(sierra-to-casm): Removed CellExpression unrequired clone. #9526
• Improve sierra debug info serde. #9525
• refactor(utils): Simplified serde implementation of map and set wrappers. #9519
• main

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[reviewable-StarkWare]

This change is 

[eytan-starkware]

@eytan-starkware reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @orizi and @TomerStarkware).

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crates/cairo-lang-sierra-gas/src/compute_costs.rs line 110 at r1 (raw file):

        // Keys are unique since we're iterating over value's keys.
        PreCost(CostTokenMap::unchecked_from_iter(
            value.0.iter().filter_map(|(k, v)| (*v >= 0).then_some((*k, *v))),

Why is it ok to have a non-full map here? Shouldn't rectify have a zero default for anything negative?

[orizi]

@orizi made 1 comment.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @eytan-starkware and @TomerStarkware).

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crates/cairo-lang-sierra-gas/src/compute_costs.rs line 110 at r1 (raw file):

Previously, eytan-starkware wrote…

Why is it ok to have a non-full map here? Shouldn't rectify have a zero default for anything negative?

the map already is a result of a sub operation - 0 values have been removed. no reason to keep values as 0.

[eytan-starkware]

@eytan-starkware reviewed 1 file and all commit messages, made 1 comment, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @TomerStarkware).