(feat): Added an optimization dump for each phase under a special log target

[eytan-starkware]

Summary

Adds tracing instrumentation to the optimization pipeline that logs the lowered IR before any optimization phases run and after each individual phase completes. Logs are emitted at the info level under the optimization_dump target, including the function's full path and the formatted lowered representation.

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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

⚠️ 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.

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Why is this change needed?

Without visibility into the intermediate lowered IR states between optimization phases, it is difficult to debug incorrect or unexpected transformations introduced by a specific phase. This change makes it possible to trace exactly how the lowered IR evolves through each optimization step.

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What was the behavior or documentation before?

The optimization pipeline applied each phase sequentially with no observable output about the intermediate IR states.

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What is the behavior or documentation after?

When tracing is enabled at the info level for the optimization_dump target, the lowered IR is logged before any phases run and after each phase completes, labeled with the function's full path and the phase name.

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Related issue or discussion (if any)

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Additional context

The logs can be selectively enabled using a tracing subscriber filtered to the optimization_dump target, making this a low-overhead addition when tracing is not active.

[reviewable-StarkWare]

This change is 

[eytan-starkware]

• (optimization): Using equality analysis for variable forwarding #9874
• (feat): Added an optimization dump for each phase under a special log target #9873 👈 (View in Graphite)
• (feat): merging analysis tests #9872
• (feat): dominator analysis using forward dataflow #9871
• (feat): def site analysis based on forward dataflow #9870
• (refactor): preserve partial struct construct info during merge with FieldVar placeholders #9804
• refactor: unify hashcons reverse maps and class_info into a single ClassInfo struct #9848
• main

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[cursor]

PR Summary

Low Risk
Low risk: adds tracing::trace! instrumentation to the optimization pipeline without changing optimization behavior. Main concern is potential log/formatting overhead when the optimization_dump target is enabled at trace level.

Overview
Adds an optimization dump trace stream in the lowering optimization pipeline.

When applying an OptimizationStrategy, it now logs the formatted lowered IR once before any phases run and again after each phase, under the optimization_dump tracing target, annotated with the function path and phase name.

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[chatgpt-codex-connector]

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[orizi]

@orizi made 2 comments.
Reviewable status: 0 of 1 files reviewed, 3 unresolved discussions (waiting on eytan-starkware and TomerStarkware).

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crates/cairo-lang-lowering/src/optimizations/strategy.rs line 144 at r1 (raw file):

    ) -> Maybe<()> {
        let fmt = crate::fmt::LoweredFormatter::new(db, &lowered.variables);
        tracing::info!(

Suggestion:

        tracing::trace!(

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crates/cairo-lang-lowering/src/optimizations/strategy.rs line 154 at r1 (raw file):

            phase.apply(db, function, lowered)?;
            let fmt = crate::fmt::LoweredFormatter::new(db, &lowered.variables);
            tracing::info!(

Suggestion:

            tracing::trace!(

[eytan-starkware]

@eytan-starkware made 3 comments.
Reviewable status: 0 of 1 files reviewed, 3 unresolved discussions (waiting on orizi and TomerStarkware).

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crates/cairo-lang-lowering/src/optimizations/strategy.rs line 144 at r1 (raw file):

    ) -> Maybe<()> {
        let fmt = crate::fmt::LoweredFormatter::new(db, &lowered.variables);
        tracing::info!(

Done.

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crates/cairo-lang-lowering/src/optimizations/strategy.rs line 154 at r1 (raw file):

            phase.apply(db, function, lowered)?;
            let fmt = crate::fmt::LoweredFormatter::new(db, &lowered.variables);
            tracing::info!(

Done.

[orizi]

@orizi reviewed 1 file and all commit messages, made 1 comment, and resolved 2 discussions.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on TomerStarkware).

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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