RJIT: Distinguish Pointer with Array

This is more convenient for accessing those fields.

lib/ruby_vm/rjit/c_pointer.rb

@@ -238,6 +238,40 @@ def self.[]=(addr, value)
       end
     end
 
+    # Basically Immediate but without #* to skip auto-dereference of structs.
+    class Array
+      attr_reader :type
+
+      # @param addr [Integer]
+      # @param type [Class] RubyVM::RJIT::CType::*
+      def initialize(addr, type)
+        @addr = addr
+        @type = type
+      end
+
+      # Array access
+      def [](index)
+        @type.new(@addr)[index]
+      end
+
+      # Array set
+      # @param index [Integer]
+      # @param value [Integer, RubyVM::RJIT::CPointer::Struct] an address itself or an object that return an address with to_i
+      def []=(index, value)
+        @type.new(@addr)[index] = value
+      end
+
+      private
+
+      def self.define(block)
+        Class.new(self) do
+          define_method(:initialize) do |addr|
+            super(addr, block.call)
+          end
+        end
+      end
+    end
+
     class Pointer
       attr_reader :type
 

lib/ruby_vm/rjit/c_type.rb

@@ -62,6 +62,14 @@ def self.new
       end
     end
 
+    class Array
+      def self.new(&block)
+        CPointer.with_class_name('Array', block.object_id.to_s) do
+          CPointer::Array.define(block)
+        end
+      end
+    end
+
     class Pointer
       # This takes a block to avoid "stack level too deep" on a cyclic reference
       # @param block [Proc]

rjit_c.rb

@@ -820,7 +820,7 @@ def C.RArray
           ), Primitive.cexpr!("OFFSETOF(((struct RArray *)NULL)->as.heap, aux)")],
           ptr: [CType::Pointer.new { self.VALUE }, Primitive.cexpr!("OFFSETOF(((struct RArray *)NULL)->as.heap, ptr)")],
         ),
-        ary: CType::Pointer.new { self.VALUE },
+        ary: CType::Array.new { self.VALUE },
       ), Primitive.cexpr!("OFFSETOF((*((struct RArray *)NULL)), as)")],
     )
   end
@@ -848,7 +848,7 @@ def C.RObject
           ivptr: [CType::Pointer.new { self.VALUE }, Primitive.cexpr!("OFFSETOF(((struct RObject *)NULL)->as.heap, ivptr)")],
           iv_index_tbl: [CType::Pointer.new { self.rb_id_table }, Primitive.cexpr!("OFFSETOF(((struct RObject *)NULL)->as.heap, iv_index_tbl)")],
         ),
-        ary: CType::Pointer.new { self.VALUE },
+        ary: CType::Array.new { self.VALUE },
       ), Primitive.cexpr!("OFFSETOF((*((struct RObject *)NULL)), as)")],
     )
   end
@@ -871,7 +871,7 @@ def C.RString
         ),
         embed: CType::Struct.new(
           "", Primitive.cexpr!("SIZEOF(((struct RString *)NULL)->as.embed)"),
-          ary: [CType::Pointer.new { CType::Immediate.parse("char") }, Primitive.cexpr!("OFFSETOF(((struct RString *)NULL)->as.embed, ary)")],
+          ary: [CType::Array.new { CType::Immediate.parse("char") }, Primitive.cexpr!("OFFSETOF(((struct RString *)NULL)->as.embed, ary)")],
         ),
       ), Primitive.cexpr!("OFFSETOF((*((struct RString *)NULL)), as)")],
     )
@@ -888,7 +888,7 @@ def C.RStruct
           len: [CType::Immediate.parse("long"), Primitive.cexpr!("OFFSETOF(((struct RStruct *)NULL)->as.heap, len)")],
           ptr: [CType::Pointer.new { self.VALUE }, Primitive.cexpr!("OFFSETOF(((struct RStruct *)NULL)->as.heap, ptr)")],
         ),
-        ary: CType::Pointer.new { self.VALUE },
+        ary: CType::Array.new { self.VALUE },
       ), Primitive.cexpr!("OFFSETOF((*((struct RStruct *)NULL)), as)")],
     )
   end

tool/rjit/bindgen.rb

@@ -296,7 +296,7 @@ def generate_node(node, sizeof_type: nil)
   # @param type [String]
   def generate_type(type)
     if type.match?(/\[\d+\]\z/)
-      return "CType::Pointer.new { #{generate_type(type.sub!(/\[\d+\]\z/, ''))} }"
+      return "CType::Array.new { #{generate_type(type.sub!(/\[\d+\]\z/, ''))} }"
     end
     type = type.delete_suffix('const')
     if type.end_with?('*')