Rewrite Kernel#tap with Ruby (#3281)

* Rewrite Kernel#tap with Ruby

This was good for VM too, but of course my intention is to unblock JIT's inlining of a block over yield
(inlining invokeyield has not been committed though).

* Fix test_settracefunc

About the :tap deletions, the :tap events are actually traced (we already have a TracePoint test for builtin methods),
but it's filtered out by tp.path == "xyzzy" (it became "<internal:kernel>"). We could trace tp.path == "<internal:kernel>"
cases too, but the lineno is impacted by kernel.rb changes and I didn't want to make it fragile for kernel.rb lineno changes.

4 files changed, 32 insertions, 38 deletions

diff --git a/benchmark/kernel_tap.yml b/benchmark/kernel_tap.yml
new file mode 100644
index 0000000000..4dcbb31b4d
--- /dev/null
+++ b/benchmark/kernel_tap.yml
@@ -0,0 +1,6 @@
+prelude: |
+  obj = Object.new
+  x = nil
+benchmark:
+  kernel_tap: obj.tap { |o| x = o }
+loop_count: 20000000
diff --git a/kernel.rb b/kernel.rb
index d00ba3a809..3404053d84 100644
--- a/kernel.rb
+++ b/kernel.rb
@@ -48,6 +48,28 @@ module Kernel
     Primitive.rb_obj_clone2(freeze)
   end
 
+  #
+  #  call-seq:
+  #     obj.tap {|x| block }    -> obj
+  #
+  #  Yields self to the block, and then returns self.
+  #  The primary purpose of this method is to "tap into" a method chain,
+  #  in order to perform operations on intermediate results within the chain.
+  #
+  #     (1..10)                  .tap {|x| puts "original: #{x}" }
+  #       .to_a                  .tap {|x| puts "array:    #{x}" }
+  #       .select {|x| x.even? } .tap {|x| puts "evens:    #{x}" }
+  #       .map {|x| x*x }        .tap {|x| puts "squares:  #{x}" }
+  #
+  #--
+  # \private
+  #++
+  #
+  def tap
+    yield(self)
+    self
+  end
+
   module_function
 
   #
diff --git a/object.c b/object.c
index c4a0d3c7ee..4718fad66f 100644
--- a/object.c
+++ b/object.c
@@ -938,31 +938,6 @@ rb_class_search_ancestor(VALUE cl, VALUE c)
     return class_search_ancestor(cl, RCLASS_ORIGIN(c));
 }
 
-/**
- *  call-seq:
- *     obj.tap {|x| block }    -> obj
- *
- *  Yields self to the block, and then returns self.
- *  The primary purpose of this method is to "tap into" a method chain,
- *  in order to perform operations on intermediate results within the chain.
- *
- *     (1..10)                  .tap {|x| puts "original: #{x}" }
- *       .to_a                  .tap {|x| puts "array:    #{x}" }
- *       .select {|x| x.even? } .tap {|x| puts "evens:    #{x}" }
- *       .map {|x| x*x }        .tap {|x| puts "squares:  #{x}" }
- *
- *--
- * \private
- *++
- */
-
-VALUE
-rb_obj_tap(VALUE obj)
-{
-    rb_yield(obj);
-    return obj;
-}
-
 
 /*
  * Document-method: inherited
@@ -4638,7 +4613,6 @@ InitVM_Object(void)
     rb_define_method(rb_mKernel, "instance_of?", rb_obj_is_instance_of, 1);
     rb_define_method(rb_mKernel, "kind_of?", rb_obj_is_kind_of, 1);
     rb_define_method(rb_mKernel, "is_a?", rb_obj_is_kind_of, 1);
-    rb_define_method(rb_mKernel, "tap", rb_obj_tap, 0);
 
     rb_define_global_function("sprintf", f_sprintf, -1);
     rb_define_global_function("format", f_sprintf, -1);
diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index 3aaa34ff73..f688e5a9aa 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -485,8 +485,6 @@ class TestSetTraceFunc < Test::Unit::TestCase
      [:c_call,   4, 'xyzzy', Integer,     :times,           1,           :outer, :nothing],
      [:line,     4, 'xyzzy', self.class,  method,           self,        nil,    :nothing],
      [:line,     5, 'xyzzy', self.class,  method,           self,        :inner, :nothing],
-     [:c_call,   5, 'xyzzy', Kernel,      :tap,             self,        :inner, :nothing],
-     [:c_return, 5, "xyzzy", Kernel,      :tap,             self,        :inner, self],
      [:c_return, 4, "xyzzy", Integer,     :times,           1,           :outer, 1],
      [:line,     7, 'xyzzy', self.class,  method,           self,        :outer, :nothing],
      [:c_call,   7, "xyzzy", Class,       :inherited,       Object,      :outer, :nothing],
@@ -512,8 +510,6 @@ class TestSetTraceFunc < Test::Unit::TestCase
      [:call,    13, "xyzzy", xyzzy.class, :bar,             xyzzy,       nil, :nothing],
      [:line,    14, "xyzzy", xyzzy.class, :bar,             xyzzy,       nil, :nothing],
      [:line,    15, "xyzzy", xyzzy.class, :bar,             xyzzy,       :XYZZY_bar, :nothing],
-     [:c_call,  15, "xyzzy", Kernel,      :tap,             xyzzy,       :XYZZY_bar, :nothing],
-     [:c_return,15, "xyzzy", Kernel,      :tap,             xyzzy,       :XYZZY_bar, xyzzy],
      [:return,  16, "xyzzy", xyzzy.class, :bar,             xyzzy,       :XYZZY_bar, xyzzy],
      [:return,  12, "xyzzy", xyzzy.class, :foo,             xyzzy,       :XYZZY_foo, xyzzy],
      [:line,    20, "xyzzy", TestSetTraceFunc, method,      self,        :outer, :nothing],
@@ -610,8 +606,6 @@ class TestSetTraceFunc < Test::Unit::TestCase
      [:c_call,   4, 'xyzzy', Integer,     :times,           1,           :outer, :nothing],
      [:line,     4, 'xyzzy', self.class,  method,           self,        nil,    :nothing],
      [:line,     5, 'xyzzy', self.class,  method,           self,        :inner, :nothing],
-     [:c_call,   5, 'xyzzy', Kernel,      :tap,             self,        :inner, :nothing],
-     [:c_return, 5, "xyzzy", Kernel,      :tap,             self,        :inner, self],
      [:c_return, 4, "xyzzy", Integer,     :times,           1,           :outer, 1],
      [:line,     7, 'xyzzy', self.class,  method,           self,        :outer, :nothing],
      [:c_call,   7, "xyzzy", Class,       :inherited,       Object,      :outer, :nothing],
@@ -637,8 +631,6 @@ class TestSetTraceFunc < Test::Unit::TestCase
      [:call,    13, "xyzzy", xyzzy.class, :bar,             xyzzy,       nil, :nothing],
      [:line,    14, "xyzzy", xyzzy.class, :bar,             xyzzy,       nil, :nothing],
      [:line,    15, "xyzzy", xyzzy.class, :bar,             xyzzy,       :XYZZY_bar, :nothing],
-     [:c_call,  15, "xyzzy", Kernel,      :tap,             xyzzy,       :XYZZY_bar, :nothing],
-     [:c_return,15, "xyzzy", Kernel,      :tap,             xyzzy,       :XYZZY_bar, xyzzy],
      [:return,  16, "xyzzy", xyzzy.class, :bar,             xyzzy,       :XYZZY_bar, xyzzy],
      [:return,  12, "xyzzy", xyzzy.class, :foo,             xyzzy,       :XYZZY_foo, xyzzy],
      [:line,    20, "xyzzy", TestSetTraceFunc, method,      self,        :outer, :nothing],
@@ -1685,7 +1677,7 @@ class TestSetTraceFunc < Test::Unit::TestCase
     TracePoint.new(:return, &capture_events).enable{
       o.alias_m
     }
-    assert_equal [[:return, :m, :alias_m]], events
+    assert_equal [[:return, :tap, :tap], [:return, :m, :alias_m]], events
     events.clear
 
     o = Class.new{
@@ -1709,13 +1701,13 @@ class TestSetTraceFunc < Test::Unit::TestCase
     events.clear
 
     o = Class.new{
-      alias alias_tap tap
-      define_method(:m){alias_tap{return}}
+      alias alias_singleton_class singleton_class
+      define_method(:m){alias_singleton_class}
     }.new
     TracePoint.new(:c_return, &capture_events).enable{
       o.m
     }
-    assert_equal [[:c_return, :tap, :alias_tap]], events
+    assert_equal [[:c_return, :singleton_class, :alias_singleton_class]], events
     events.clear
 
     c = Class.new{