[NFC] Refactor Heap2Local logic

src/ir/branch-utils.h

@@ -109,11 +109,11 @@ void operateOnScopeNameUsesAndSentValues(Expression* expr, T func) {
       func(name, sw->value);
     } else if (auto* br = expr->dynCast<BrOn>()) {
       func(name, br->ref);
-    } else if (auto* tt = expr->dynCast<TryTable>()) {
+    } else if (expr->is<TryTable>()) {
       // The values are supplied by throwing instructions, so we are unable to
       // know what they will be here.
       func(name, nullptr);
-    } else if (auto* res = expr->dynCast<Resume>()) {
+    } else if (expr->is<Resume>()) {
       // The values are supplied by suspend instructions executed while running
       // the continuation, so we are unable to know what they will be here.
       func(name, nullptr);
@@ -419,10 +419,14 @@ struct BranchTargets {
 
   // Gets the expression that defines this branch target, i.e., where we branch
   // to if we branch to that name.
-  Expression* getTarget(Name name) { return inner.targets[name]; }
+  Expression* getTarget(Name name) const {
+    auto iter = inner.targets.find(name);
+    assert(iter != inner.targets.end());
+    return iter->second;
+  }
 
   // Gets the expressions branching to a target.
-  std::unordered_set<Expression*> getBranches(Name name) {
+  std::unordered_set<Expression*> getBranches(Name name) const {
     auto iter = inner.branches.find(name);
     if (iter != inner.branches.end()) {
       return iter->second;

src/ir/parents.h

@@ -24,7 +24,13 @@ namespace wasm {
 struct Parents {
   Parents(Expression* expr) { inner.walk(expr); }
 
-  Expression* getParent(Expression* curr) { return inner.parentMap[curr]; }
+  Expression* getParent(Expression* curr) const {
+    auto iter = inner.parentMap.find(curr);
+    if (iter != inner.parentMap.end()) {
+      return iter->second;
+    }
+    return nullptr;
+  }
 
 private:
   struct Inner