Improve sierra debug info serde.

[orizi]

Summary

Refactored the serialization and deserialization of OrderedHashMap in the debug info module to use a more efficient approach. Instead of collecting items into a temporary vector, the implementation now directly serializes elements into a sequence. For deserialization, introduced a custom Visitor implementation that properly handles sequence access and constructs the map directly.

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Type of change

Please check one:

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

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Why is this change needed?

The previous implementation of serialization and deserialization for OrderedHashMap was inefficient as it created intermediate collections. This change improves performance by eliminating the need for temporary vectors during serialization and deserialization processes.

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What was the behavior or documentation before?

Previously, the code would collect all map entries into a temporary vector during serialization, and similarly deserialize into a vector before converting back to an OrderedHashMap.

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What is the behavior or documentation after?

Now the implementation directly serializes map entries into a sequence without the intermediate collection. For deserialization, a custom Visitor implementation properly handles sequence access and constructs the map directly with appropriate size hints when available.

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Additional context

This change follows serialization best practices by using the visitor pattern for deserialization and direct sequence serialization, which should be more memory efficient for large maps.

[orizi]

• performance(sierra-gas): Smaller equivalent costs map. #9535
• 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 👈 (View in Graphite)
• 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 3 comments.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @orizi and @TomerStarkware).

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crates/cairo-lang-sierra/src/debug_info.rs line 208 at r1 (raw file):

    serializer: S,
) -> Result<S::Ok, S::Error> {
    let mut seq = serializer.serialize_seq(Some(m.len()))?;

Why not serializer.collect_seq(...)?

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

        type Value = OrderedHashMap<Id, SmolStr>;

        fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {

Essentially reimplementing indexmap: https://docs.rs/indexmap/latest/src/indexmap/map/serde_seq.rs.html#1-138

[orizi]

@orizi made 2 comments.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @eytan-starkware and @TomerStarkware).

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crates/cairo-lang-sierra/src/debug_info.rs line 208 at r1 (raw file):

Previously, eytan-starkware wrote…

Why not serializer.collect_seq(...)?

Done.

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

Previously, eytan-starkware wrote…

Essentially reimplementing indexmap: https://docs.rs/indexmap/latest/src/indexmap/map/serde_seq.rs.html#1-138

cool.
Done.

[TomerStarkware]

@TomerStarkware reviewed all commit messages and made 1 comment.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @eytan-starkware).

[eytan-starkware]

@eytan-starkware made 1 comment.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @orizi).

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crates/cairo-lang-sierra/src/debug_info.rs line 208 at r1 (raw file):

Previously, orizi wrote…

Done.

not seeing it

[eytan-starkware]

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

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

Previously, orizi wrote…

cool.
Done.

No change here as well

[orizi]

@orizi made 2 comments.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @eytan-starkware).

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crates/cairo-lang-sierra/src/debug_info.rs line 208 at r1 (raw file):

Previously, eytan-starkware wrote…

not seeing it

got the wrong PR - done now.

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

Previously, eytan-starkware wrote…

No change here as well

same - yeah - it is essentially the same thing.

[eytan-starkware]

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

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

Previously, orizi wrote…

same - yeah - it is essentially the same thing.

And we are already using the indexmap serialization in other places. Why reimplement? We have 3 ordered hash map de/serialize

[orizi]

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

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crates/cairo-lang-sierra/src/debug_info.rs line 228 at r1 (raw file):

Previously, eytan-starkware wrote…

And we are already using the indexmap serialization in other places. Why reimplement? We have 3 ordered hash map de/serialize

the id conversion is required. (Id::new(k))

[eytan-starkware]

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