opt_aset_with

lib/syntax_tree/compiler.rb

@@ -337,6 +337,24 @@ def visit_array(node)
     def visit_assign(node)
       case node.target
       when ARefField
+        if !frozen_string_literal && specialized_instruction && (node.target.index.parts.length == 1)
+          arg = node.target.index.parts.first
+
+          if arg.is_a?(StringLiteral) && (arg.parts.length == 1)
+            string_part = arg.parts.first
+
+            if string_part.is_a?(TStringContent)
+              visit(node.target.collection)
+              visit(node.value)
+              iseq.swap
+              iseq.topn(1)
+              iseq.opt_aset_with(string_part.value, :[]=, 2)
+              iseq.pop
+              return
+            end
+          end
+        end
+
         iseq.putnil
         visit(node.target.collection)
         visit(node.target.index)

lib/syntax_tree/yarv.rb

@@ -532,6 +532,11 @@ def opt_aref_with(object, method_id, argc, flag = VM_CALL_ARGS_SIMPLE)
         push([:opt_aref_with, object, call_data(method_id, argc, flag)])
       end
 
+      def opt_aset_with(object, method_id, argc, flag = VM_CALL_ARGS_SIMPLE)
+        stack.change_by(-2 + 1)
+        push([:opt_aset_with, object, call_data(method_id, argc, flag)])
+      end
+
       def opt_getconstant_path(names)
         if RUBY_VERSION >= "3.2"
           stack.change_by(+1)

test/compiler_test.rb

@@ -202,6 +202,7 @@ class CompilerTest < Minitest::Test
       "foo[bar] <<= 1",
       "foo[bar] ^= 1",
       "foo['true']",
+      "foo['true'] = 1",
       # Constants (single)
       "Foo",
       "Foo = 1",