[Python-3000-checkins] r67253 - python/branches/py3k/Python/peephole.c

[raymond.hettinger]

Author: raymond.hettinger
Date: Tue Nov 18 01:07:10 2008
New Revision: 67253

Log:
Issue 2260: Small peephole optimization -- eliminate unnecessary POP_TOP /JUMP_FORWARD 1 pairs.

Modified:
   python/branches/py3k/Python/peephole.c

Modified: python/branches/py3k/Python/peephole.c
==============================================================================
--- python/branches/py3k/Python/peephole.c	(original)
+++ python/branches/py3k/Python/peephole.c	Tue Nov 18 01:07:10 2008
@@ -430,6 +430,16 @@
 				cumlc = 0;
 				break;
 
+				/* Replace POP_TOP JUMP_FORWARD 1 POP_TOP 
+				   with    NOP NOP NOP NOP POP_TOP.           */
+			case POP_TOP:
+				if (UNCONDITIONAL_JUMP(codestr[i+1]) &&
+					GETJUMPTGT(codestr, i+1) == i+5 &&
+					codestr[i+4] == POP_TOP &&
+					ISBASICBLOCK(blocks,i,4))
+						memset(codestr+i, NOP, 4);
+				break;
+
 				/* Try to fold tuples of constants (includes a case for lists
 				   which are only used for "in" and "not in" tests).
 				   Skip over BUILD_SEQN 1 UNPACK_SEQN 1.