Flush stack upon encountering function return.

lib/furnace-avm2/abc.rb

@@ -16,6 +16,7 @@ module Furnace::AVM2::ABC
 require_relative "abc/opcodes/push_literal_opcode"
 require_relative "abc/opcodes/control_transfer_opcode"
 require_relative "abc/opcodes/function_invocation_opcode"
+require_relative "abc/opcodes/function_return_opcode"
 require_relative "abc/opcodes/property_opcode"
 
 Dir[File.join(File.dirname(__FILE__), "abc", "opcodes", "*", "*.rb")].each do |file|

lib/furnace-avm2/abc/opcodes/function_return/as3_returnvalue.rb

@@ -1,5 +1,5 @@
 module Furnace::AVM2::ABC
-  class AS3ReturnValue < Opcode
+  class AS3ReturnValue < FunctionReturnOpcode
     instruction 0x48
 
     consume 1

lib/furnace-avm2/abc/opcodes/function_return/as3_returnvoid.rb

@@ -1,5 +1,5 @@
 module Furnace::AVM2::ABC
-  class AS3ReturnVoid < Opcode
+  class AS3ReturnVoid < FunctionReturnOpcode
     instruction 0x47
 
     consume 0

lib/furnace-avm2/abc/opcodes/function_return_opcode.rb

@@ -0,0 +1,4 @@
+module Furnace::AVM2::ABC
+  class FunctionReturnOpcode < Opcode
+  end
+ end

lib/furnace-avm2/transform/ast_build.rb

@@ -195,6 +195,14 @@ def transform(code, body)
             node.children.concat opcode.parameters
             node.children.concat parameters
 
+            # Spec does not require stack to be empty upon encountering return.
+            # If there's something left, it should have been here.
+            if opcode.is_a? ABC::FunctionReturnOpcode
+              while @stack.any?
+                emit(*consume(1))
+              end
+            end
+
             # All opcodes which produce 2 results--that is, dup and swap--
             # are already handled at the top.
             if opcode.produces == 0