Issue #9225: Remove the ROT_FOUR and DUP_TOPX opcode, the latter replaced

by the new (and simpler) DUP_TOP_TWO.  Performance isn't changed, but
our bytecode is a bit simplified.  Patch by Demur Rumed.

4 files changed, 17 insertions, 46 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 4d583a5..1f78f95 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1420,50 +1420,21 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
             SET_THIRD(v);
             FAST_DISPATCH();
 
-        TARGET(ROT_FOUR)
-            u = TOP();
-            v = SECOND();
-            w = THIRD();
-            x = FOURTH();
-            SET_TOP(v);
-            SET_SECOND(w);
-            SET_THIRD(x);
-            SET_FOURTH(u);
-            FAST_DISPATCH();
-
         TARGET(DUP_TOP)
             v = TOP();
             Py_INCREF(v);
             PUSH(v);
             FAST_DISPATCH();
 
-        TARGET(DUP_TOPX)
-            if (oparg == 2) {
-                x = TOP();
-                Py_INCREF(x);
-                w = SECOND();
-                Py_INCREF(w);
-                STACKADJ(2);
-                SET_TOP(x);
-                SET_SECOND(w);
-                FAST_DISPATCH();
-            } else if (oparg == 3) {
-                x = TOP();
-                Py_INCREF(x);
-                w = SECOND();
-                Py_INCREF(w);
-                v = THIRD();
-                Py_INCREF(v);
-                STACKADJ(3);
-                SET_TOP(x);
-                SET_SECOND(w);
-                SET_THIRD(v);
-                FAST_DISPATCH();
-            }
-            Py_FatalError("invalid argument to DUP_TOPX"
-                          " (bytecode corruption?)");
-            /* Never returns, so don't bother to set why. */
-            break;
+        TARGET(DUP_TOP_TWO)
+            x = TOP();
+            Py_INCREF(x);
+            w = SECOND();
+            Py_INCREF(w);
+            STACKADJ(2);
+            SET_TOP(x);
+            SET_SECOND(w);
+            FAST_DISPATCH();
 
         TARGET(UNARY_POSITIVE)
             v = TOP();
diff --git a/Python/compile.c b/Python/compile.c
index aae0339..6963a15 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -680,8 +680,8 @@ opcode_stack_effect(int opcode, int oparg)
             return 0;
         case DUP_TOP:
             return 1;
-        case ROT_FOUR:
-            return 0;
+        case DUP_TOP_TWO:
+            return 2;
 
         case UNARY_POSITIVE:
         case UNARY_NEGATIVE:
@@ -782,8 +782,6 @@ opcode_stack_effect(int opcode, int oparg)
             return -1;
         case DELETE_GLOBAL:
             return 0;
-        case DUP_TOPX:
-            return oparg;
         case LOAD_CONST:
             return 1;
         case LOAD_NAME:
@@ -3404,7 +3402,7 @@ compiler_handle_subscr(struct compiler *c, const char *kind,
             return 0;
     }
     if (ctx == AugLoad) {
-        ADDOP_I(c, DUP_TOPX, 2);
+        ADDOP(c, DUP_TOP_TWO);
     }
     else if (ctx == AugStore) {
         ADDOP(c, ROT_THREE);
diff --git a/Python/import.c b/Python/import.c
index a5277af..d6b19e8 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -101,12 +101,14 @@ typedef unsigned short mode_t;
                introduce POP_JUMP_IF_FALSE and POP_JUMP_IF_TRUE)
        Python 3.2a0: 3160 (add SETUP_WITH)
                      tag: cpython-32
+       Python 3.2a1: 3170 (add DUP_TOP_TWO, remove DUP_TOPX and ROT_FOUR)
+                     tag: cpython-32
 */
 
 /* If you change MAGIC, you must change TAG and you must insert the old value
    into _PyMagicNumberTags below.
 */
-#define MAGIC (3160 | ((long)'\r'<<16) | ((long)'\n'<<24))
+#define MAGIC (3170 | ((long)'\r'<<16) | ((long)'\n'<<24))
 #define TAG "cpython-32"
 #define CACHEDIR "__pycache__"
 /* Current magic word and string tag as globals. */
diff --git a/Python/opcode_targets.h b/Python/opcode_targets.h
index 20c9f25..8b59c2d 100644
--- a/Python/opcode_targets.h
+++ b/Python/opcode_targets.h
@@ -4,7 +4,7 @@ static void *opcode_targets[256] = {
     &&TARGET_ROT_TWO,
     &&TARGET_ROT_THREE,
     &&TARGET_DUP_TOP,
-    &&TARGET_ROT_FOUR,
+    &&TARGET_DUP_TOP_TWO,
     &&_unknown_opcode,
     &&_unknown_opcode,
     &&_unknown_opcode,
@@ -98,7 +98,7 @@ static void *opcode_targets[256] = {
     &&TARGET_DELETE_ATTR,
     &&TARGET_STORE_GLOBAL,
     &&TARGET_DELETE_GLOBAL,
-    &&TARGET_DUP_TOPX,
+    &&_unknown_opcode,
     &&TARGET_LOAD_CONST,
     &&TARGET_LOAD_NAME,
     &&TARGET_BUILD_TUPLE,