Added expression degrees.

[Alon-Ti]

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[reviewable-StarkWare]

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[Alon-Ti]

• Added expression degrees. #931 👈 (View in Graphite)
• dev

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.33333% with 9 lines in your changes missing coverage. Please review.

Project coverage is 91.44%. Comparing base (8550b7d) to head (f835cb8).

Files with missing lines	Patch %	Lines
...tes/prover/src/constraint_framework/expr/degree.rs	83.33%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #931      +/-   ##
==========================================
- Coverage   91.48%   91.44%   -0.04%     
==========================================
  Files          98       99       +1     
  Lines       13733    13787      +54     
  Branches    13733    13787      +54     
==========================================
+ Hits        12563    12608      +45     
- Misses       1055     1064       +9     
  Partials      115      115              

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[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 2.

Benchmark suite	Current: f835cb8	Previous: cd8b37b	Ratio
merkle throughput/simd merkle	28569815 ns/iter (± 434865)	13712527 ns/iter (± 579195)	2.08

This comment was automatically generated by workflow using github-action-benchmark.

CC: @shaharsamocha7

[shaharsamocha7]

Reviewable status: 0 of 2 files reviewed, 3 unresolved discussions (waiting on @Alon-Ti)

---

crates/prover/src/constraint_framework/expr/degree.rs line 8 at r2 (raw file):

///        simplification.
///     2. If expressions p and q cancel out under some operation, this will not be accounted
///        for, so that (x^2 + 1) - (x^2 + x) will return degree 2.

You should mention that this is poly in the trace cells, right?

Code quote:

/// Finds a degree bound for an expressions.
/// Computes the actual degree with the following caveats:
///     1. The constant expression 0 receives degree 0 like all other constants rather than the
///        mathematically correcy -infinity. This means, for example, that expresisons of the
///        type 0 * expr will return degree deg expr. This should be mitigated by
///        simplification.
///     2. If expressions p and q cancel out under some operation, this will not be accounted
///        for, so that (x^2 + 1) - (x^2 + x) will return degree 2.

---

crates/prover/src/constraint_framework/expr/degree.rs line 20 at r2 (raw file):

    exprs: HashMap<String, BaseExpr>,
    ext_exprs: HashMap<String, ExtExpr>,
}

Why this struct is here?
Also, why do we have a degree_bound function for this struct?
Isn't it enough to impl degree_bound for BaseExpr, ExtExpr and that's it?

Code quote:

/// A struct of named expressions that can be searched when determining the degree bound for an
/// expression that contains parameters.
pub struct NamedExprs {
    exprs: HashMap<String, BaseExpr>,
    ext_exprs: HashMap<String, ExtExpr>,
}

---

crates/prover/src/constraint_framework/expr/degree.rs line 81 at r2 (raw file):

    #[test]
    fn test_degree_bound() {
        let intermediate = (felt!(12) + col!(1, 1, 0)) * var!("a") * col!(1, 0, 0);

Remind me what var is? Is it counted as a constant?

Code quote:

var!("a")