From 130ef3b458e61b37a05690b1aee59d748543bfa6 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 23 Aug 2018 07:22:27 +0000
Subject: [PATCH] compile.c: drop unused string

* compile.c (iseq_peephole_optimize): drop unused dynamic string
  literal, without concatenation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64516 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 compile.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/compile.c b/compile.c
index ef92a83846..d34376c572 100644
--- a/compile.c
+++ b/compile.c
@@ -2942,6 +2942,15 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
 	    else if (previ == BIN(newarray) && iseq_pop_newarray(iseq, (INSN*)prev)) {
 		ELEM_REMOVE(&iobj->link);
 	    }
+	    else if (previ == BIN(concatstrings)) {
+		if (OPERAND_AT(prev, 0) == INT2FIX(1)) {
+		    ELEM_REMOVE(prev);
+		}
+		else {
+		    ELEM_REMOVE(&iobj->link);
+		    INSN_OF(prev) = BIN(adjuststack);
+		}
+	    }
 	}
     }