duparray.diff

From 8f74c91274a7e1072685aded111e89d55ced0f96 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <[email protected]>
Date: Sun, 21 Oct 2018 16:12:16 -0700
Subject: [PATCH] Collapse putobject, putobject, newarray

This collapses:

```== disasm: #<ISeq:[email protected]:3 (3,0)-(5,3)> (catch: FALSE)
0000 putobject                    "a"                                 (   4)[LiCa]
0002 putobject                    "b"
0004 putobject                    "c"
0006 putobject                    "d"
0008 putobject                    "e"
0010 putobject                    "f"
0012 putobject                    "g"
0014 putobject                    "h"
0016 putobject                    "i"
0018 putobject                    "j"
0020 putobject                    "k"
0022 newarray                     11
0024 leave                                                            (   5)[Re]
```

In to this:

```
== disasm: #<ISeq:[email protected]:3 (3,0)-(5,3)> (catch: FALSE)
0000 duparray                     ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"](   4)[LiCa]
0002 leave                                                            (   5)[Re]
```
---
 compile.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/compile.c b/compile.c
index 272b9ddacc..ed21cbb1d1 100644
--- a/compile.c
+++ b/compile.c
@@ -2796,6 +2796,44 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	}
     }
 
+    if (IS_INSN_ID(iobj, newarray)) {
+	int len;
+
+	len = NUM2INT(OPERAND_AT(iobj, 0));
+
+	if (len > 0) {
+	    INSN *link;
+	    INSN *cur;
+	    int i;
+
+	    link = iobj;
+	    i = len;
+	    while(i > 0) {
+		link = (INSN *)get_prev_insn(link);
+		if (!IS_INSN_ID(link, putobject))
+		    break;
+
+		i--;
+	    }
+
+	    /* All previous instructions were `putobject` */
+	    if (i == 0) {
+		VALUE list = rb_ary_new_capa(len);
+		iseq_add_mark_object_compile_time(iseq, list);
+
+		while(i < len) {
+		    cur = link;
+		    rb_ary_push(list, OPERAND_AT(cur, 0));
+		    link = (INSN *)get_next_insn(link);
+		    ELEM_REMOVE(&cur->link);
+		    i++;
+		}
+		iobj->insn_id = BIN(duparray);
+		OPERAND_AT(iobj, 0) = list;
+	    }
+	}
+    }
+
     if (IS_INSN_ID(iobj, leave)) {
 	remove_unreachable_chunk(iseq, iobj->link.next);
     }
-- 
2.17.0