feat: avoid duplicate arrays in SSA

compiler/noirc_evaluator/src/ssa/ir/dfg.rs

@@ -52,6 +52,10 @@ pub(crate) struct DataFlowGraph {
     #[serde(skip)]
     constants: HashMap<(FieldElement, Type), ValueId>,
 
+    /// Each array is unique. Attempting to insert an array with the same
+    /// list of values will return the same ValueId.
+    arrays: HashMap<(im::Vector<ValueId>, Type), ValueId>,
+
     /// Contains each function that has been imported into the current function.
     /// A unique `ValueId` for each function's [`Value::Function`] is stored so any given FunctionId
     /// will always have the same ValueId within this function.
@@ -268,8 +272,14 @@ impl DataFlowGraph {
 
     /// Create a new constant array value from the given elements
     pub(crate) fn make_array(&mut self, array: im::Vector<ValueId>, typ: Type) -> ValueId {
+        if let Some(id) = self.arrays.get(&(array.clone(), typ.clone())) {
+            return *id;
+        }
+
         assert!(matches!(typ, Type::Array(..) | Type::Slice(_)));
-        self.make_value(Value::Array { array, typ })
+        let id = self.make_value(Value::Array { array: array.clone(), typ: typ.clone() });
+        self.arrays.insert((array, typ), id);
+        id
     }
 
     /// Gets or creates a ValueId for the given FunctionId.

compiler/noirc_evaluator/src/ssa/ir/function_inserter.rs

@@ -51,6 +51,14 @@ impl<'f> FunctionInserter<'f> {
 
                     let new_array_clone = new_array.clone();
                     let new_id = self.function.dfg.make_array(new_array, typ.clone());
+
+                    // If we got the same value (can happen because a function's dfg will cache
+                    // identical arrays) we don't cache the new value as it would end to an infinite loop
+                    // when trying to resolve it.
+                    if new_id == value {
+                        return value;
+                    }
+
                     self.values.insert(value, new_id);
                     self.const_arrays.insert((new_array_clone, typ), new_id);
                     new_id

compiler/noirc_evaluator/src/ssa/opt/constant_folding.rs

@@ -844,9 +844,7 @@ mod test {
         assert_eq!(instructions.len(), 10);
     }
 
-    // This test currently fails. It being fixed will address the issue https://github.com/noir-lang/noir/issues/5756
     #[test]
-    #[should_panic]
     fn constant_array_deduplication() {
         // fn main f0 {
         //   b0(v0: u64):