Eliminate data dependency in predict macro.

Added two predictions:
  GET_ITER --> FOR_ITER
  FOR_ITER --> STORE_FAST or UNPACK_SEQUENCE

Improves timings on pybench and timeit.py. Pystone results are neutral.

diff --git a/Python/ceval.c b/Python/ceval.c
index 38edb73bd0658724cbf04629d0c3a6efcd6366a0..f965d3866bb9fa17eb155b1f15ef2c9de7033886 100644 (file)
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -620,8 +620,8 @@ eval_frame(PyFrameObject *f)
 
 #define PREDICT(op)            if (*next_instr == op) goto PRED_##op
 #define PREDICTED(op)          PRED_##op: next_instr++
-#define PREDICTED_WITH_ARG(op) PRED_##op: oparg = (next_instr += 3, \
-                               (next_instr[-1]<<8) + next_instr[-2])
+#define PREDICTED_WITH_ARG(op) PRED_##op: oparg = (next_instr[2]<<8) + \
+                               next_instr[1]; next_instr += 3
 
 /* Stack manipulation macros */
 
@@ -889,6 +889,7 @@ eval_frame(PyFrameObject *f)
                        PUSH(x);
                        goto fast_next_opcode;
 
+               PREDICTED_WITH_ARG(STORE_FAST);
                case STORE_FAST:
                        v = POP();
                        SETLOCAL(oparg, v);
@@ -1675,6 +1676,7 @@ eval_frame(PyFrameObject *f)
                                                        NAME_ERROR_MSG ,w);
                        break;
 
+               PREDICTED_WITH_ARG(UNPACK_SEQUENCE);
                case UNPACK_SEQUENCE:
                        v = POP();
                        if (PyTuple_CheckExact(v)) {
@@ -2051,17 +2053,21 @@ eval_frame(PyFrameObject *f)
                        Py_DECREF(v);
                        if (x != NULL) {
                                SET_TOP(x);
+                               PREDICT(FOR_ITER);
                                continue;
                        }
                        STACKADJ(-1);
                        break;
 
+               PREDICTED_WITH_ARG(FOR_ITER);
                case FOR_ITER:
                        /* before: [iter]; after: [iter, iter()] *or* [] */
                        v = TOP();
                        x = PyIter_Next(v);
                        if (x != NULL) {
                                PUSH(x);
+                               PREDICT(STORE_FAST);
+                               PREDICT(UNPACK_SEQUENCE);
                                continue;
                        }
                        if (!PyErr_Occurred()) {