Refactored boxed deconstruct signature code, creating reusable functions

[eytan-starkware]

Summary

Refactored the struct boxed deconstruct libfunc to improve handling of output variable references. This PR:

1. Extracted common utility functions to a new utils.rs module:

   • Added unwrap_snapshot_type to handle snapshot type detection and unwrapping
   • Added boxed_output_var_info to create boxed output variables consistently

2. Improved the struct deconstruction logic:

   • Replaced the manual snapshot detection with the new utility function
   • Restructured the output variable creation to properly handle zero-sized types
   • Made the code more maintainable by separating analysis and signature creation

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Type of change

Please check one:

• Performance improvement

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Why is this change needed?

The previous implementation of struct boxed deconstruction had complex logic for handling output variable references, especially when dealing with zero-sized types. This refactoring makes the code more maintainable and consistent by extracting common patterns into utility functions and improving the handling of output variable references.

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What was the behavior or documentation before?

The struct boxed deconstruct libfunc had complex inline logic for handling snapshots and determining output variable references. The code was less maintainable and had a more complex approach to handling zero-sized types.

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What is the behavior or documentation after?

The functionality remains the same, but the code is now more maintainable with:

• Clear separation between type analysis and signature creation
• Utility functions for common operations
• Improved handling of output variable references for zero-sized types
• More consistent approach to boxed output variables

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Additional context

This refactoring is part of ongoing efforts to improve the maintainability of the Sierra codebase, particularly around struct operations and boxed types.

[eytan-starkware]

• (opt): Libfunc for matching on a boxed enum for boxed variants results #9378
• (refactor): Build jump and jump table to support prepended instructions. #9463
• Refactored boxed deconstruct signature code, creating reusable functions #9462 👈 (View in Graphite)
• (test): Adding casm run and trace to e2e tests #9482
• main

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[reviewable-StarkWare]

This change is 

[orizi]

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

---

crates/cairo-lang-sierra/src/extensions/modules/structure.rs line 284 at r1 (raw file):

impl StructBoxedDeconstructLibfunc {
    /// Analyzes a struct type to extract member types and snapshot information.

restore doc.

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 135 at r1 (raw file):

/// Returns the inner type and whether the provided type is a snapshot.
pub fn unwrap_snapshot_type(

Suggestion:

pub fn peel_snapshot(

[orizi]

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

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 155 at r1 (raw file):

) -> Result<OutputVarInfo, SpecializationError> {
    let inner_type = if is_snapshot { snapshot_ty(context, component_ty)? } else { component_ty };
    Ok(OutputVarInfo { ty: box_ty(context, inner_type)?, ref_info })

the ref_info part is only confusing.

just handle the typing.

Code quote:

/// Helper to create a boxed output variable for unpack operations.
pub fn boxed_output_var_info(
    context: &dyn SignatureSpecializationContext,
    component_ty: ConcreteTypeId,
    is_snapshot: bool,
    ref_info: OutputVarReferenceInfo,
) -> Result<OutputVarInfo, SpecializationError> {
    let inner_type = if is_snapshot { snapshot_ty(context, component_ty)? } else { component_ty };
    Ok(OutputVarInfo { ty: box_ty(context, inner_type)?, ref_info })

[TomerStarkware]

@TomerStarkware reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: 1 of 2 files reviewed, 3 unresolved discussions (waiting on @eytan-starkware and @ilyalesokhin-starkware).

[eytan-starkware]

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

---

crates/cairo-lang-sierra/src/extensions/modules/structure.rs line 284 at r1 (raw file):

Previously, orizi wrote…

restore doc.

Done.

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 155 at r1 (raw file):

Previously, orizi wrote…

the ref_info part is only confusing.

just handle the typing.

Done.

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 135 at r1 (raw file):

/// Returns the inner type and whether the provided type is a snapshot.
pub fn unwrap_snapshot_type(

Done.

[orizi]

@orizi reviewed all commit messages and made 2 comments.
Reviewable status: 0 of 2 files reviewed, 5 unresolved discussions (waiting on @eytan-starkware, @ilyalesokhin-starkware, and @TomerStarkware).

---

crates/cairo-lang-sierra/src/extensions/modules/structure.rs line 321 at r2 (raw file):

        let mut outputs = Vec::with_capacity(member_types.len());

        for member_ty in member_types.by_ref() {

this change broke the current logic.
would probably change tests after rebase as well.

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 152 at r2 (raw file):

    component_ty: ConcreteTypeId,
    is_snapshot: bool,
) -> Result<ConcreteTypeId, SpecializationError> {

or something better - as the output isn't relevant now.

Suggestion:

/// Helper to create a boxed output variable for unpack operations.
pub fn boxed_ty_with_snapshot(
    context: &dyn SignatureSpecializationContext,
    component_ty: ConcreteTypeId,
    is_snapshot: bool,
) -> Result<ConcreteTypeId, SpecializationError> {

[eytan-starkware]

@eytan-starkware made 2 comments.
Reviewable status: 0 of 2 files reviewed, 5 unresolved discussions (waiting on @ilyalesokhin-starkware, @orizi, and @TomerStarkware).

---

crates/cairo-lang-sierra/src/extensions/modules/structure.rs line 321 at r2 (raw file):

Previously, orizi wrote…

this change broke the current logic.
would probably change tests after rebase as well.

f2f

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 152 at r2 (raw file):

Previously, orizi wrote…

or something better - as the output isn't relevant now.

Done.

[orizi]

@orizi reviewed 2 files and all commit messages, made 1 comment, and resolved 5 discussions.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @eytan-starkware and @ilyalesokhin-starkware).

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 145 at r3 (raw file):

        Ok((ty, false))
    }
}

Suggestion:

pub fn peel_snapshot(
    context: &dyn SignatureSpecializationContext,
    ty: &ConcreteTypeId,
) -> Result<(&ConcreteTypeId, bool), SpecializationError> {
    let type_info = context.get_type_info(ty)?;
    if type_info.long_id.generic_id == SnapshotType::id() {
        Ok((args_as_single_type(&type_info.long_id.generic_args)?, true))
    } else {
        Ok((ty, false))
    }
}

[eytan-starkware]

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

---

crates/cairo-lang-sierra/src/extensions/modules/utils.rs line 145 at r3 (raw file):

        Ok((ty, false))
    }
}

Done

[orizi]

@orizi reviewed 2 files and all commit messages, made 1 comment, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ilyalesokhin-starkware).

[graphite-app]

Merge activity

• Jan 20, 12:58 PM UTC: This pull request can not be added to the Graphite merge queue. Please try rebasing and resubmitting to merge when ready.
• Jan 20, 12:58 PM UTC: Graphite disabled "merge when ready" on this PR due to: a merge conflict with the target branch; resolve the conflict and try again..

[orizi]

@orizi reviewed 1 file and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ilyalesokhin-starkware).