fix: Avoid non-determinism in defunctionalization

crates/noirc_evaluator/src/ssa_refactor/ir/function.rs

@@ -141,7 +141,7 @@ impl std::fmt::Display for RuntimeType {
 /// within Call instructions.
 pub(crate) type FunctionId = Id<Function>;
 
-#[derive(Debug, Default, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Default, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub(crate) struct Signature {
     pub(crate) params: Vec<Type>,
     pub(crate) returns: Vec<Type>,

crates/noirc_evaluator/src/ssa_refactor/ir/types.rs

@@ -10,15 +10,15 @@ use iter_extended::vecmap;
 ///
 /// Fields do not have a notion of ordering, so this distinction
 /// is reasonable.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub(crate) enum NumericType {
     Signed { bit_size: u32 },
     Unsigned { bit_size: u32 },
     NativeField,
 }
 
 /// All types representable in the IR.
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub(crate) enum Type {
     /// Represents numeric types in the IR, including field elements
     Numeric(NumericType),

crates/noirc_evaluator/src/ssa_refactor/opt/defunctionalize.rs

@@ -4,7 +4,7 @@
 //! with a non-literal target can be replaced with a call to an apply function.
 //! The apply function is a dispatch function that takes the function id as a parameter
 //! and dispatches to the correct target.
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 
 use acvm::FieldElement;
 use iter_extended::vecmap;
@@ -47,7 +47,6 @@ struct ApplyFunction {
 /// And creating apply functions that dispatch to the correct target by runtime comparisons with constants
 #[derive(Debug, Clone)]
 struct DefunctionalizationContext {
-    fn_to_runtime: HashMap<FunctionId, RuntimeType>,
     apply_functions: HashMap<Signature, ApplyFunction>,
 }
 
@@ -57,10 +56,8 @@ impl Ssa {
         let variants = find_variants(&self);
 
         let apply_functions = create_apply_functions(&mut self, variants);
-        let fn_to_runtime =
-            self.functions.iter().map(|(func_id, func)| (*func_id, func.runtime())).collect();
 
-        let context = DefunctionalizationContext { fn_to_runtime, apply_functions };
+        let context = DefunctionalizationContext { apply_functions };
 
         context.defunctionalize_all(&mut self);
         self
@@ -157,23 +154,23 @@ impl DefunctionalizationContext {
 }
 
 /// Collects all functions used as values that can be called by their signatures
-fn find_variants(ssa: &Ssa) -> HashMap<Signature, Vec<FunctionId>> {
-    let mut dynamic_dispatches: HashSet<Signature> = HashSet::new();
-    let mut functions_as_values: HashSet<FunctionId> = HashSet::new();
+fn find_variants(ssa: &Ssa) -> BTreeMap<Signature, Vec<FunctionId>> {
+    let mut dynamic_dispatches: BTreeSet<Signature> = BTreeSet::new();
+    let mut functions_as_values: BTreeSet<FunctionId> = BTreeSet::new();
 
     for function in ssa.functions.values() {
         functions_as_values.extend(find_functions_as_values(function));
         dynamic_dispatches.extend(find_dynamic_dispatches(function));
     }
 
-    let mut signature_to_functions_as_value: HashMap<Signature, Vec<FunctionId>> = HashMap::new();
+    let mut signature_to_functions_as_value: BTreeMap<Signature, Vec<FunctionId>> = BTreeMap::new();
 
     for function_id in functions_as_values {
         let signature = ssa.functions[&function_id].signature();
         signature_to_functions_as_value.entry(signature).or_default().push(function_id);
     }
 
-    let mut variants = HashMap::new();
+    let mut variants = BTreeMap::new();
 
     for dispatch_signature in dynamic_dispatches {
         let mut target_fns = vec![];
@@ -189,8 +186,8 @@ fn find_variants(ssa: &Ssa) -> HashMap<Signature, Vec<FunctionId>> {
 }
 
 /// Finds all literal functions used as values in the given function
-fn find_functions_as_values(func: &Function) -> HashSet<FunctionId> {
-    let mut functions_as_values: HashSet<FunctionId> = HashSet::new();
+fn find_functions_as_values(func: &Function) -> BTreeSet<FunctionId> {
+    let mut functions_as_values: BTreeSet<FunctionId> = BTreeSet::new();
 
     let mut process_value = |value_id: ValueId| {
         if let Value::Function(id) = func.dfg[value_id] {
@@ -220,8 +217,8 @@ fn find_functions_as_values(func: &Function) -> HashSet<FunctionId> {
 }
 
 /// Finds all dynamic dispatch signatures in the given function
-fn find_dynamic_dispatches(func: &Function) -> HashSet<Signature> {
-    let mut dispatches = HashSet::new();
+fn find_dynamic_dispatches(func: &Function) -> BTreeSet<Signature> {
+    let mut dispatches = BTreeSet::new();
 
     for block_id in func.reachable_blocks() {
         let block = &func.dfg[block_id];
@@ -246,7 +243,7 @@ fn find_dynamic_dispatches(func: &Function) -> HashSet<Signature> {
 
 fn create_apply_functions(
     ssa: &mut Ssa,
-    variants_map: HashMap<Signature, Vec<FunctionId>>,
+    variants_map: BTreeMap<Signature, Vec<FunctionId>>,
 ) -> HashMap<Signature, ApplyFunction> {
     let mut apply_functions = HashMap::new();
     for (signature, variants) in variants_map.into_iter() {