Avoid #set_class in IO.popen and create the right object from the start

Author: eregon

src/main/ruby/core/io.rb

@@ -805,27 +805,8 @@ def self.parse_mode(mode)
     ret
   end
 
-  def self.pipe(external=nil, internal=nil, options=nil)
-    fds = FFI::MemoryPointer.new(:int, 2) do |ptr|
-      r = Truffle::POSIX.pipe(ptr)
-      Errno.handle if r == -1
-      ptr.read_array_of_int(2)
-    end
-
-    lhs = self.new(fds[0], RDONLY)
-    rhs = self.new(fds[1], WRONLY)
-
-    lhs.close_on_exec = true
-    rhs.close_on_exec = true
-
-    lhs.set_encoding external || Encoding.default_external,
-                     internal || Encoding.default_internal, options
-
-    lhs.sync = true
-    rhs.sync = true
-
-    lhs.pipe = true
-    rhs.pipe = true
+  def self.pipe(external = nil, internal = nil, options = nil)
+    lhs, rhs = Truffle::IOOperations.create_pipe(self, self, external, internal, options)
 
     if block_given?
       begin
@@ -881,16 +862,14 @@ def self.popen(*args)
       readable = true
     end
 
-    pa_read, ch_write = pipe if readable
+    # We only need the Bidirectional pipe if we're reading and writing.
+    # Otherwise, we can just return the IO object for the proper half.
+    read_class = (readable && writable) ? IO::BidirectionalPipe : self
+
+    pa_read, ch_write = Truffle::IOOperations.create_pipe(read_class, self) if readable
     ch_read, pa_write = pipe if writable
 
-    # We only need the Bidirectional pipe if we're reading and writing.
-    # If we're only doing one, we can just return the IO object for
-    # the proper half.
     if readable and writable
-      # Transmogrify pa_read into a BidirectionalPipe object,
-      # and then tell it about its pid and pa_write
-      Truffle::Internal::Unsafe.set_class pa_read, IO::BidirectionalPipe
       pipe = pa_read
       pipe.set_pipe_info(pa_write)
     elsif readable

src/main/ruby/core/truffle/io_operations.rb

@@ -13,10 +13,12 @@ module IOOperations
     def self.last_line(a_binding)
       Truffle::KernelOperations.frame_local_variable_get(:$_, a_binding)
     end
+    Truffle::Graal.always_split(method(:last_line))
 
     def self.set_last_line(value, a_binding)
       Truffle::KernelOperations.frame_local_variable_set(:$_, a_binding, value)
     end
+    Truffle::Graal.always_split(method(:set_last_line))
 
     def self.print(io, args, last_line_binding)
       if args.empty?
@@ -96,7 +98,27 @@ def self.dup2_with_cloexec(old_fd, new_fd)
       end
     end
 
-    Truffle::Graal.always_split(method(:last_line))
-    Truffle::Graal.always_split(method(:set_last_line))
+    def self.pipe_end_setup(io)
+      io.close_on_exec = true
+      io.sync = true
+      io.pipe = true
+      io
+    end
+
+    def self.create_pipe(read_class, write_class, external = nil, internal = nil, options = nil)
+      fds = Truffle::FFI::MemoryPointer.new(:int, 2) do |ptr|
+        res = Truffle::POSIX.pipe(ptr)
+        Errno.handle if res == -1
+        ptr.read_array_of_int(2)
+      end
+
+      lhs = pipe_end_setup(read_class.new(fds[0], IO::RDONLY))
+      rhs = pipe_end_setup(write_class.new(fds[1], IO::WRONLY))
+
+      lhs.set_encoding external || Encoding.default_external,
+                       internal || Encoding.default_internal, options
+
+      [lhs, rhs]
+    end
   end
 end