SF patch #670367: Micro-optimizations for ceval.c

Make the code slightly shorter, faster, and easier to
read.

* Eliminate unused DUP_TOPX code for x==1.
compile.c always generates DUP_TOP instead.

* Since only two cases remain for DUP_TOPX, replace
the switch-case with if-elseif.

* The in-lined integer compare does a CheckExact on
both arguments. Since the second is a little more
likely to fail, test it first.

* The switch-case for IS/IS_NOT and IN/NOT_IN can
separate the regular and inverted cases with no
additional work. For all four paths, saves a test and
jump.

diff --git a/Python/ceval.c b/Python/ceval.c
index 1fab1cca9e15178941f5fa8dcbb5cae88c78b882..8547f85c1fb3cc1503d9cf17eed2a22a7c145c6e 100644 (file)
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -855,14 +855,7 @@ eval_frame(PyFrameObject *f)
                        continue;
 
                case DUP_TOPX:
-                       switch (oparg) {
-                       case 1:
-                               x = TOP();
-                               Py_INCREF(x);
-                               STACKADJ(1);
-                               SET_TOP(x);
-                               continue;
-                       case 2:
+                       if (oparg == 2) {
                                x = TOP();
                                Py_INCREF(x);
                                w = SECOND();
@@ -871,7 +864,7 @@ eval_frame(PyFrameObject *f)
                                SET_TOP(x);
                                SET_SECOND(w);
                                continue;
-                       case 3:
+                       } else if (oparg == 3) {
                                x = TOP();
                                Py_INCREF(x);
                                w = SECOND();
@@ -883,10 +876,9 @@ eval_frame(PyFrameObject *f)
                                SET_SECOND(w);
                                SET_THIRD(v);
                                continue;
-                       default:
-                               Py_FatalError("invalid argument to DUP_TOPX"
-                                             " (bytecode corruption?)");
                        }
+                       Py_FatalError("invalid argument to DUP_TOPX"
+                                     " (bytecode corruption?)");
                        break;
 
                case UNARY_POSITIVE:
@@ -1842,7 +1834,7 @@ eval_frame(PyFrameObject *f)
                case COMPARE_OP:
                        w = POP();
                        v = TOP();
-                       if (PyInt_CheckExact(v) && PyInt_CheckExact(w)) {
+                       if (PyInt_CheckExact(w) && PyInt_CheckExact(v)) {
                                /* INLINE: cmp(int, int) */
                                register long a, b;
                                register int res;
@@ -3581,18 +3573,21 @@ cmp_outcome(int op, register PyObject *v, register PyObject *w)
        int res = 0;
        switch (op) {
        case PyCmp_IS:
-       case PyCmp_IS_NOT:
                res = (v == w);
-               if (op == (int) PyCmp_IS_NOT)
-                       res = !res;
+               break;
+       case PyCmp_IS_NOT:
+               res = (v != w);
                break;
        case PyCmp_IN:
+               res = PySequence_Contains(w, v);
+               if (res < 0)
+                       return NULL;
+               break;
        case PyCmp_NOT_IN:
                res = PySequence_Contains(w, v);
                if (res < 0)
                        return NULL;
-               if (op == (int) PyCmp_NOT_IN)
-                       res = !res;
+               res = !res;
                break;
        case PyCmp_EXC_MATCH:
                res = PyErr_GivenExceptionMatches(v, w);