Raymond's patch for #1819: speedup function calls with named parameters

(35% faster according to pybench)

diff --git a/Python/ceval.c b/Python/ceval.c
index f61bcd51b2a68e2a8ee4360b15db38ce3a8040a0..6eef7efa84b11ab40a4692548c670b8e00ed3898 100644 (file)
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -640,9 +640,9 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
        processor's own internal branch predication has a high likelihood of
        success, resulting in a nearly zero-overhead transition to the
        next opcode.  A successful prediction saves a trip through the eval-loop
-       including its two unpredictable branches, the HAS_ARG test and the 
+       including its two unpredictable branches, the HAS_ARG test and the
        switch-case.  Combined with the processor's internal branch prediction,
-       a successful PREDICT has the effect of making the two opcodes run as if 
+       a successful PREDICT has the effect of making the two opcodes run as if
        they were a single new opcode with the bodies combined.
 
     If collecting opcode statistics, your choices are to either keep the
@@ -737,7 +737,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
                           an argument which depends on the situation.
                           The global trace function is also called
                           whenever an exception is detected. */
-                       if (call_trace_protected(tstate->c_tracefunc, 
+                       if (call_trace_protected(tstate->c_tracefunc,
                                                 tstate->c_traceobj,
                                                 f, PyTrace_CALL, Py_None)) {
                                /* Trace function raised an error */
@@ -769,10 +769,10 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
           this wasn't always true before 2.3!  PyFrame_New now sets
           f->f_lasti to -1 (i.e. the index *before* the first instruction)
           and YIELD_VALUE doesn't fiddle with f_lasti any more.  So this
-          does work.  Promise. 
+          does work.  Promise.
 
           When the PREDICT() macros are enabled, some opcode pairs follow in
-           direct succession without updating f->f_lasti.  A successful 
+           direct succession without updating f->f_lasti.  A successful
            prediction effectively links the two codes together as if they
            were a single new opcode; accordingly,f->f_lasti will point to
            the first code in the pair (for instance, GET_ITER followed by
@@ -2210,7 +2210,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
                            because it prevents detection of a control-break in tight loops like
                            "while 1: pass".  Compile with this option turned-on when you need
                            the speed-up and do not need break checking inside tight loops (ones
-                           that contain only instructions ending with goto fast_next_opcode). 
+                           that contain only instructions ending with goto fast_next_opcode).
                         */
                        goto fast_next_opcode;
 #else
@@ -2779,6 +2779,7 @@ PyEval_EvalCodeEx(PyCodeObject *co, PyObject *globals, PyObject *locals,
                        }
                }
                for (i = 0; i < kwcount; i++) {
+                       PyObject **co_varnames;
                        PyObject *keyword = kws[2*i];
                        PyObject *value = kws[2*i + 1];
                        int j;
@@ -2788,14 +2789,21 @@ PyEval_EvalCodeEx(PyCodeObject *co, PyObject *globals, PyObject *locals,
                                    PyString_AsString(co->co_name));
                                goto fail;
                        }
-                       /* XXX slow -- speed up using dictionary? */
+                       /* Speed hack: do raw pointer compares. As names are
+                          normally interned this should almost always hit. */
+                       co_varnames = PySequence_Fast_ITEMS(co->co_varnames);
                        for (j = 0; j < co->co_argcount; j++) {
-                               PyObject *nm = PyTuple_GET_ITEM(
-                                       co->co_varnames, j);
+                               PyObject *nm = co_varnames[j];
+                               if (nm == keyword)
+                                       goto kw_found;
+                       }
+                       /* Slow fallback, just in case */
+                       for (j = 0; j < co->co_argcount; j++) {
+                               PyObject *nm = co_varnames[j];
                                int cmp = PyObject_RichCompareBool(
                                        keyword, nm, Py_EQ);
                                if (cmp > 0)
-                                       break;
+                                       goto kw_found;
                                else if (cmp < 0)
                                        goto fail;
                        }
@@ -2812,20 +2820,20 @@ PyEval_EvalCodeEx(PyCodeObject *co, PyObject *globals, PyObject *locals,
                                        goto fail;
                                }
                                PyDict_SetItem(kwdict, keyword, value);
+                               continue;
                        }
-                       else {
-                               if (GETLOCAL(j) != NULL) {
-                                       PyErr_Format(PyExc_TypeError,
-                                            "%.200s() got multiple "
-                                            "values for keyword "
-                                            "argument '%.400s'",
-                                            PyString_AsString(co->co_name),
-                                            PyString_AsString(keyword));
-                                       goto fail;
-                               }
-                               Py_INCREF(value);
-                               SETLOCAL(j, value);
+kw_found:
+                       if (GETLOCAL(j) != NULL) {
+                               PyErr_Format(PyExc_TypeError,
+                                               "%.200s() got multiple "
+                                               "values for keyword "
+                                               "argument '%.400s'",
+                                               PyString_AsString(co->co_name),
+                                               PyString_AsString(keyword));
+                               goto fail;
                        }
+                       Py_INCREF(value);
+                       SETLOCAL(j, value);
                }
                if (argcount < co->co_argcount) {
                        int m = co->co_argcount - defcount;