Update the peephole optimizer to remove more dead code (jumps after returns)
and inline jumps to returns.
diff --git a/Python/import.c b/Python/import.c
index a90729a..45c5507 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -65,9 +65,10 @@
Python 2.5c1: 62121 (fix wrong lnotab with for loops and
storing constants that should have been removed)
Python 2.5c2: 62131 (fix wrong code: for x, in ... in listcomp/genexp)
+ Python 2.6a0: 62141 (peephole optimizations)
.
*/
-#define MAGIC (62131 | ((long)'\r'<<16) | ((long)'\n'<<24))
+#define MAGIC (62141 | ((long)'\r'<<16) | ((long)'\n'<<24))
/* Magic word as global; note that _PyImport_Init() can change the
value of this global to accommodate for alterations of how the
diff --git a/Python/peephole.c b/Python/peephole.c
index 1d94319..f2fe6ce 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -523,6 +523,13 @@
case SETUP_EXCEPT:
case SETUP_FINALLY:
tgt = GETJUMPTGT(codestr, i);
+ /* Replace JUMP_* to a RETURN into just a RETURN */
+ if (UNCONDITIONAL_JUMP(opcode) &&
+ codestr[tgt] == RETURN_VALUE) {
+ codestr[i] = RETURN_VALUE;
+ memset(codestr+i+1, NOP, 2);
+ continue;
+ }
if (!UNCONDITIONAL_JUMP(codestr[tgt]))
continue;
tgttgt = GETJUMPTGT(codestr, tgt);
@@ -540,12 +547,16 @@
goto exitUnchanged;
/* Replace RETURN LOAD_CONST None RETURN with just RETURN */
+ /* Remove unreachable JUMPs after RETURN */
case RETURN_VALUE:
- if (i+4 >= codelen ||
- codestr[i+4] != RETURN_VALUE ||
- !ISBASICBLOCK(blocks,i,5))
+ if (i+4 >= codelen)
continue;
- memset(codestr+i+1, NOP, 4);
+ if (codestr[i+4] == RETURN_VALUE &&
+ ISBASICBLOCK(blocks,i,5))
+ memset(codestr+i+1, NOP, 4);
+ else if (UNCONDITIONAL_JUMP(codestr[i+1]) &&
+ ISBASICBLOCK(blocks,i,4))
+ memset(codestr+i+1, NOP, 3);
break;
}
}