Use a shared array for the duparray instruction

tenderlove · tenderlove · commit d46cd60f3cfb · 2018-11-29T20:39:51.000Z
In this example code:

```ruby
def foo
  [1, 2, 3, 4]
end
```

The array literal uses a `duparray` instruction. Before this patch,
`rb_ary_resurrect` would malloc and memcpy a new array buffer.  This
patch changes `rb_ary_resurrect` to use `ary_make_partial` so that the
new array object shares the underlying buffer with the array stored in
the instruction sequences.

Before this patch, the new array object is not shared:

```
$ ruby -r objspace -e'p ObjectSpace.dump([1, 2, 3, 4])'
"{\"address\":\"0x7fa2718372d0\", \"type\":\"ARRAY\", \"class\":\"0x7fa26f8b0010\", \"length\":4, \"memsize\":72, \"flags\":{\"wb_protected\":true}}\n"
```

After this patch:

```
$ ./ruby -r objspace -e'p ObjectSpace.dump([1, 2, 3, 4])'
"{\"address\":\"0x7f9a76883638\", \"type\":\"ARRAY\", \"class\":\"0x7f9a758af900\", \"length\":4, \"shared\":true, \"references\":[\"0x7f9a768837c8\"], \"memsize\":40, \"flags\":{\"wb_protected\":true}}\n"
```

[Feature #15289] [ruby-core:90097]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66095 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
diff --git a/array.c b/array.c
@@ -2191,7 +2191,7 @@ rb_ary_dup(VALUE ary)
 VALUE
 rb_ary_resurrect(VALUE ary)
 {
-    return rb_ary_new4(RARRAY_LEN(ary), RARRAY_CONST_PTR_TRANSIENT(ary));
+    return ary_make_partial(ary, rb_cArray, 0, RARRAY_LEN(ary));
 }
 
 extern VALUE rb_output_fs;

Original file line number	Diff line number	Diff line change
`@@ -2191,7 +2191,7 @@ rb_ary_dup(VALUE ary)`
`2191`	`2191`	`VALUE`
`2192`	`2192`	`rb_ary_resurrect(VALUE ary)`
`2193`	`2193`	`{`
`2194`		`- return rb_ary_new4(RARRAY_LEN(ary), RARRAY_CONST_PTR_TRANSIENT(ary));`
	`2194`	`+ return ary_make_partial(ary, rb_cArray, 0, RARRAY_LEN(ary));`
`2195`	`2195`	`}`
`2196`	`2196` 3E9A
`2197`	`2197`	`extern VALUE rb_output_fs;`