nobu	2017-10-22 10:46:43 +0900 (Sun, 22 Oct 2017)

  New Revision: 60340

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=60340

  Log:
    compile.c: optimize local variable assignments
    
    * compile.c (iseq_peephole_optimize): eliminate simple self
      assignments of a local variable when the result is used.
      follow-up of r60322.

  Modified files:
    trunk/compile.c
Index: compile.c
===================================================================
--- compile.c	(revision 60339)
+++ compile.c	(revision 60340)
@@ -2597,12 +2597,16 @@ iseq_peephole_optimize(rb_iseq_t *iseq, https://github.com/ruby/ruby/blob/trunk/compile.c#L2597
     }
 
     if (IS_INSN_ID(iobj, getlocal)) {
-	if (IS_NEXT_INSN_ID(&iobj->link, setlocal)) {
-	    LINK_ELEMENT *set1 = iobj->link.next;
+	LINK_ELEMENT *niobj = &iobj->link;
+	if (IS_NEXT_INSN_ID(niobj, dup)) {
+	    niobj = niobj->next;
+	}
+	if (IS_NEXT_INSN_ID(niobj, setlocal)) {
+	    LINK_ELEMENT *set1 = niobj->next;
 	    if (OPERAND_AT(iobj, 0) == OPERAND_AT(set1, 0) &&
 		OPERAND_AT(iobj, 1) == OPERAND_AT(set1, 1)) {
 		REMOVE_ELEM(set1);
-		REMOVE_ELEM(&iobj->link);
+		REMOVE_ELEM(niobj);
 	    }
 	}
     }

--
ML: ruby-changes@q...
Info: http://www.atdot.net/~ko1/quickml/