nobu	2015-11-18 11:32:17 +0900 (Wed, 18 Nov 2015)

  New Revision: 52633

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=52633

  Log:
    compile.c: optimize useless branches
    
    * compile.c (iseq_peephole_optimize): eliminate always/never
      branches after a literal object.  this sequence typically
      appears by defined? operator for a method call on a local
      variable.

  Modified files:
    trunk/ChangeLog
    trunk/compile.c
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 52632)
+++ ChangeLog	(revision 52633)
@@ -1,3 +1,10 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Wed Nov 18 11:32:15 2015  Nobuyoshi Nakada  <nobu@r...>
+
+	* compile.c (iseq_peephole_optimize): eliminate always/never
+	  branches after a literal object.  this sequence typically
+	  appears by defined? operator for a method call on a local
+	  variable.
+
 Wed Nov 18 10:33:06 2015  NAKAMURA Usaku  <usa@r...>
 
 	* ext/socket/ancdata.c (bsock_recvmsg_internal): stretch the buffer size
Index: compile.c
===================================================================
--- compile.c	(revision 52632)
+++ compile.c	(revision 52633)
@@ -2031,6 +2031,33 @@ iseq_peephole_optimize(rb_iseq_t *iseq, https://github.com/ruby/ruby/blob/trunk/compile.c#L2031
 		 */
 		replace_destination(iobj, nobj);
 	    }
+	    else if (pobj) {
+		int cond;
+		if (pobj->insn_id == BIN(putobject)) {
+		    cond = (iobj->insn_id == BIN(branchif) ?
+			    OPERAND_AT(pobj, 0) != Qfalse :
+			    iobj->insn_id == BIN(branchunless) ?
+			    OPERAND_AT(pobj, 0) == Qfalse :
+			    FALSE);
+		}
+		else if (pobj->insn_id == BIN(putstring)) {
+		    cond = iobj->insn_id == BIN(branchif);
+		}
+		else if (pobj->insn_id == BIN(putnil)) {
+		    cond = iobj->insn_id != BIN(branchif);
+		}
+		else break;
+		REMOVE_ELEM(&pobj->link);
+		if (cond) {
+		    iobj->insn_id = BIN(jump);
+		    goto again;
+		}
+		else {
+		    unref_destination(iobj);
+		    REMOVE_ELEM(&iobj->link);
+		}
+		break;
+	    }
 	    else break;
 	    nobj = (INSN *)get_destination_insn(nobj);
 	}

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