flow-control: Support lowering of EqualsLiteral node.

[liorgold2]

Stack:

• flow-control: Add tests. #8136
• flow-control: Support a graph with no branching. #8135
• flow-control: Add numeric+tuple+bindings test. #8132
• flow-control: Support lowering of EqualsLiteral node. #8131 ⬅

⚠️ Part of a stack created by spr. Do not merge manually using the UI - doing so may have unexpected results.

[reviewable-StarkWare]

This change is 

[ilyalesokhin-starkware]

crates/cairo-lang-lowering/src/lower/mod.rs line 950 at r1 (raw file):

/// Lowers a semantic expression that is a literal, possibly including a negation.
fn lower_expr_literal_helper<'db>(

Suggestion:

/// Lowers a semantic expression that is a literal, possibly including a negation.
fn lower_expr_literal<'db>(
    ctx: &mut LoweringContext<'db, '_>,
    expr: &semantic::ExprLiteral<'db>,
    builder: &mut BlockBuilder<'db>,
) -> LoweringResult<'db, LoweredExpr<'db>> {
    log::trace!("Lowering a literal: {:?}", expr.debug(&ctx.expr_formatter));
    Ok(LoweredExpr::AtVariable(lower_expr_literal_helper(
        ctx,
        expr.stable_ptr.untyped(),
        expr.ty,
        &expr.value,
        builder,
    )))
}


fn lower_expr_literal_to_var_usage<'db>(

[ilyalesokhin-starkware]

crates/cairo-lang-lowering/src/lower/flow_control/graph.rs line 118 at r1 (raw file):

    /// The literal to check against.
    pub literal: usize,
    /// A stable pointer to the first instance of the literal in the patterns.

What is the literal?

Suggestion:

a literal

[ilyalesokhin-starkware]

crates/cairo-lang-lowering/src/lower/flow_control/lower_graph/lower_node.rs line 188 at r1 (raw file):

            ctx.ctx,
            literal_stable_ptr,
            felt252_ty,

Why can't the literal be u32?

Code quote:

 felt252_ty,

[liorgold2]

Reviewable status: 0 of 5 files reviewed, 3 unresolved discussions (waiting on @ilyalesokhin-starkware)

---

crates/cairo-lang-lowering/src/lower/flow_control/graph.rs line 118 at r1 (raw file):

Previously, ilyalesokhin-starkware wrote…

What is the literal?

It's the literal, as this struct is about comparing to a specific literal (this is the pub literal: usize member).
BTW (same for "the input value")

---

crates/cairo-lang-lowering/src/lower/flow_control/lower_graph/lower_node.rs line 188 at r1 (raw file):

Previously, ilyalesokhin-starkware wrote…

Why can't the literal be u32?

For now, I've copied the current implementation, which always converts to felt252 before the comparisons. (Also, I'm only supporting felt252, since I'm not actually doing the conversion).

There's the following TODO:

// TODO(TomerStarkware): Use the same type of literal as the input, without the cast to
//   felt252.

which we should consider doing (I don't know what are the implications of doing it)

---

crates/cairo-lang-lowering/src/lower/mod.rs line 950 at r1 (raw file):

/// Lowers a semantic expression that is a literal, possibly including a negation.
fn lower_expr_literal_helper<'db>(

Done.

[ilyalesokhin-starkware]

Reviewed 2 of 5 files at r1, 3 of 3 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @liorgold2)

[ilyalesokhin-starkware]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @liorgold2)