fix: flattening pass no longer overwrites previously mapped condition…

… values (#2117)

* Fix flattening pass overwriting previously mapped values

* chore: add backticks to variable names in comment

---------

Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>

crates/nargo_cli/tests/test_data/regression_2099/Nargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "regression_2099"
+authors = [""]
+compiler_version = "0.9.0"
+
+[dependencies]

crates/nargo_cli/tests/test_data/regression_2099/src/main.nr

@@ -0,0 +1,37 @@
+use dep::std::ec::tecurve::affine::Curve as AffineCurve;
+use dep::std::ec::tecurve::affine::Point as Gaffine;
+use dep::std::ec::tecurve::curvegroup::Curve;
+use dep::std::ec::tecurve::curvegroup::Point as G;
+
+use dep::std::ec::swcurve::affine::Point as SWGaffine;
+use dep::std::ec::swcurve::curvegroup::Point as SWG;
+
+use dep::std::ec::montcurve::affine::Point as MGaffine;
+use dep::std::ec::montcurve::curvegroup::Point as MG;
+
+fn main() {
+    // Define Baby Jubjub (ERC-2494) parameters in affine representation
+    let bjj_affine = AffineCurve::new(168700, 168696, Gaffine::new(995203441582195749578291179787384436505546430278305826713579947235728471134,5472060717959818805561601436314318772137091100104008585924551046643952123905));
+
+    // Test addition
+    let p1_affine = Gaffine::new(17777552123799933955779906779655732241715742912184938656739573121738514868268, 2626589144620713026669568689430873010625803728049924121243784502389097019475);
+    let p2_affine = Gaffine::new(16540640123574156134436876038791482806971768689494387082833631921987005038935, 20819045374670962167435360035096875258406992893633759881276124905556507972311);      
+    let _p3_affine = bjj_affine.add(p1_affine, p2_affine);
+
+    // Test SWCurve equivalents of the above
+    // First the affine representation
+    let bjj_swcurve_affine = bjj_affine.into_swcurve();
+
+    let p1_swcurve_affine = bjj_affine.map_into_swcurve(p1_affine);
+    let p2_swcurve_affine = bjj_affine.map_into_swcurve(p2_affine);
+
+    let _p3_swcurve_affine_from_add = bjj_swcurve_affine.add(
+        p1_swcurve_affine,
+        p2_swcurve_affine
+    );
+
+    // Check that these points are on the curve
+    assert(
+        bjj_swcurve_affine.contains(p1_swcurve_affine)
+    );            
+}

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

@@ -124,7 +124,6 @@ impl<'f> FunctionInserter<'f> {
         let old_parameters = self.function.dfg.block_parameters(block);
 
         for (param, new_param) in old_parameters.iter().zip(new_values) {
-            // Don't overwrite any existing entries to avoid overwriting the induction variable
             self.values.entry(*param).or_insert(*new_param);
         }
     }

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

@@ -274,7 +274,10 @@ impl<'f> Context<'f> {
                 // end, in addition to resetting the value of old_condition since it is set to
                 // known to be true/false within the then/else branch respectively.
                 self.insert_current_side_effects_enabled();
-                self.inserter.map_value(old_condition, old_condition);
+
+                // We must map back to `then_condition` here. Mapping `old_condition` to itself would
+                // lose any previous mappings.
+                self.inserter.map_value(old_condition, then_condition);
 
                 // While there is a condition on the stack we don't compile outside the condition
                 // until it is popped. This ensures we inline the full then and else branches