docs: Add documentation to visitor, clean up mir passes mod.rs

ir/src/passes/mod.rs

@@ -2,34 +2,25 @@ mod inlining;
 mod translate;
 mod unrolling;
 mod visitor;
-
-pub use self::inlining::Inlining;
-pub use self::translate::AstToMir;
-pub use self::unrolling::Unrolling;
+pub use inlining::Inlining;
+pub use translate::AstToMir;
+pub use unrolling::Unrolling;
+// Note: ConstantPropagation and ValueNumbering are not implemented yet in the MIR
+//mod constant_propagation;
+//mod value_numbering;
+//pub use constant_propagation::ConstantPropagation;
+//pub use value_numbering::ValueNumbering;
 
 use std::collections::HashMap;
 use std::ops::Deref;
 
-use air_pass::Pass;
 use miden_diagnostics::Spanned;
 
 use crate::ir::{
     Accessor, Add, Boundary, Call, Enf, Exp, Fold, For, If, Link, Matrix, Mul, Node, Op, Owner,
     Parameter, Parent, Sub, Value, Vector,
 };
 
-pub struct DumpAst;
-impl Pass for DumpAst {
-    type Input<'a> = air_parser::ast::Program;
-    type Output<'a> = air_parser::ast::Program;
-    type Error = air_parser::SemanticAnalysisError;
-
-    fn run<'a>(&mut self, input: Self::Input<'a>) -> Result<Self::Output<'a>, Self::Error> {
-        println!("{}", &input);
-        Ok(input)
-    }
-}
-
 /// Helper to duplicate a MIR node and its children recursively
 /// It should be used when we want to reference the same node multiple times in the MIR graph (e.g. referencing let bound variables)
 ///

ir/src/passes/visitor.rs

@@ -2,9 +2,15 @@ use crate::{
     ir::{Graph, Link, Node, Op, Parent, Root},
     CompileError,
 };
-
 use std::ops::Deref;
 
+/// A trait for visiting nodes in a MIR graph, from the leafs to the root.
+///
+/// The process is as follows:
+/// - Starting from the root_nodes_to_visit, we scan a node
+/// - We recursively scan all the children of the node
+/// - Once we have scanned all the children, we visit the node
+/// - The visit will be dispatched based on the variant of the node
 pub trait Visitor {
     fn work_stack(&mut self) -> &mut Vec<Link<Node>>;
     fn root_nodes_to_visit(&self, graph: &Graph) -> Vec<Link<Node>>;