Index: Python/peephole.c
===================================================================
--- Python/peephole.c	(revision 56631)
+++ Python/peephole.c	(working copy)
@@ -562,6 +562,20 @@
 				         ISBASICBLOCK(blocks,i,4))
 					memset(codestr+i+1, NOP, 3);
 				break;
+
+				/* Replace STORE_FAST x LOAD_FAST x with DUP_TOP STORE_FAST x
+				   Load and store must refer to the same slot. */
+			case STORE_FAST:
+				j = GETARG(codestr, i);
+				if (codestr[i+3] != LOAD_FAST ||
+				    !ISBASICBLOCK(blocks, i, 5) ||
+				    j != GETARG(codestr, i+3))
+					continue;
+				codestr[i] = DUP_TOP;
+				memset(codestr+i+1, NOP, 2);
+				codestr[i+3] = STORE_FAST;
+				SETARG(codestr, i+3, j);
+				break;
 		}
 	}