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Another ugly inlining hack, expanding the two PyDict_GetItem() calls 

in LOAD_GLOBAL.  Besides saving a C function call, it saves checks
whether f_globals and f_builtins are dicts, and extracting and testing
the string object's hash code is done only once.  We bail out of the
inlining if the name is not exactly a string, or when its hash is -1;
because of interning, neither should ever happen.  I believe interning
guarantees that the hash code is set, and I believe that the 'names'
tuple of a code object always contains interned strings, but I'm not
assuming that -- I'm simply testing hash != -1.

On my home machine, this makes a pystone variant with new-style
classes and slots run at the same speed as classic pystone!  (With
new-style classes but without slots, it is still a lot slower.)
This commit is contained in:
Guido van Rossum 2002-08-19 20:24:07 +00:00
parent e3a8e7ed1d
commit 3a4dfc87e6
1 changed files with 25 additions and 1 deletions
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26
Python/ceval.c
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@ -1709,13 +1709,37 @@ eval_frame(PyFrameObject *f)
case LOAD_GLOBAL:
w = GETITEM(names, oparg);
if (PyString_CheckExact(w)) {
long hash = ((PyStringObject *)w)->ob_shash;
if (hash != -1) {
/* Inline the PyDict_GetItem() calls */
PyDictObject *d;
d = (PyDictObject *)(f->f_globals);
x = d->ma_lookup(d, w, hash)->me_value;
if (x != NULL) {
Py_INCREF(x);
PUSH(x);
continue;
}
d = (PyDictObject *)(f->f_builtins);
x = d->ma_lookup(d, w, hash)->me_value;
if (x != NULL) {
Py_INCREF(x);
PUSH(x);
continue;
}
goto load_global_error;
}
}
/* This is the un-inlined version of the code above */
x = PyDict_GetItem(f->f_globals, w);
if (x == NULL) {
x = PyDict_GetItem(f->f_builtins, w);
if (x == NULL) {
load_global_error:
format_exc_check_arg(
PyExc_NameError,
GLOBAL_NAME_ERROR_MSG ,w);
GLOBAL_NAME_ERROR_MSG, w);
break;
}
}