[Python-checkins] r46426 - in python/trunk: Include/frameobject.h Python/ceval.c
tim.peters
python-checkins at python.org
Sat May 27 01:14:38 CEST 2006
Author: tim.peters
Date: Sat May 27 01:14:37 2006
New Revision: 46426
Modified:
python/trunk/Include/frameobject.h
python/trunk/Python/ceval.c
Log:
Patch 1145039.
set_exc_info(), reset_exc_info(): By exploiting the
likely (who knows?) invariant that when an exception's
`type` is NULL, its `value` and `traceback` are also NULL,
save some cycles in heavily-executed code.
This is a "a kronar saved is a kronar earned" patch: the
speedup isn't reliably measurable, but it obviously does
reduce the operation count in the normal (no exception
raised) path through PyEval_EvalFrameEx().
The tim-exc_sanity branch tries to push this harder, but
is still blowing up (at least in part due to pre-existing
subtle bugs that appear to have no other visible
consequences!).
Not a bugfix candidate.
Modified: python/trunk/Include/frameobject.h
==============================================================================
--- python/trunk/Include/frameobject.h (original)
+++ python/trunk/Include/frameobject.h Sat May 27 01:14:37 2006
@@ -26,7 +26,16 @@
to the current stack top. */
PyObject **f_stacktop;
PyObject *f_trace; /* Trace function */
+
+ /* If an exception is raised in this frame, the next three are used to
+ * record the exception info (if any) originally in the thread state. See
+ * comments before set_exc_info() -- it's not obvious.
+ * Invariant: if _type is NULL, then so are _value and _traceback.
+ * Desired invariant: all three are NULL, or all three are non-NULL. That
+ * one isn't currently true, but "should be".
+ */
PyObject *f_exc_type, *f_exc_value, *f_exc_traceback;
+
PyThreadState *f_tstate;
int f_lasti; /* Last instruction if called */
/* As of 2.3 f_lineno is only valid when tracing is active (i.e. when
Modified: python/trunk/Python/ceval.c
==============================================================================
--- python/trunk/Python/ceval.c (original)
+++ python/trunk/Python/ceval.c Sat May 27 01:14:37 2006
@@ -24,7 +24,7 @@
#pragma optimize("agtw", on)
#endif
-#ifndef WITH_TSC
+#ifndef WITH_TSC
#define READ_TIMESTAMP(var)
@@ -49,7 +49,7 @@
asm volatile ("mftbu %0" : "=r" (tbu2));
if (__builtin_expect(tbu != tbu2, 0)) goto loop;
- /* The slightly peculiar way of writing the next lines is
+ /* The slightly peculiar way of writing the next lines is
compiled better by GCC than any other way I tried. */
((long*)(v))[0] = tbu;
((long*)(v))[1] = tb;
@@ -62,7 +62,7 @@
#endif
-void dump_tsc(int opcode, int ticked, uint64 inst0, uint64 inst1,
+void dump_tsc(int opcode, int ticked, uint64 inst0, uint64 inst1,
uint64 loop0, uint64 loop1, uint64 intr0, uint64 intr1)
{
uint64 intr, inst, loop;
@@ -567,7 +567,7 @@
inst0 -- beginning of switch statement for opcode dispatch
inst1 -- end of switch statement (may be skipped)
loop0 -- the top of the mainloop
- loop1 -- place where control returns again to top of mainloop
+ loop1 -- place where control returns again to top of mainloop
(may be skipped)
intr1 -- beginning of long interruption
intr2 -- end of long interruption
@@ -768,7 +768,7 @@
why = WHY_EXCEPTION;
goto on_error;
}
-
+
for (;;) {
#ifdef WITH_TSC
if (inst1 == 0) {
@@ -2218,7 +2218,7 @@
re-raising the exception. (But non-local gotos
should still be resumed.)
*/
-
+
x = TOP();
u = SECOND();
if (PyInt_Check(u) || u == Py_None) {
@@ -2581,7 +2581,12 @@
}
}
- reset_exc_info(tstate);
+ if (tstate->frame->f_exc_type != NULL)
+ reset_exc_info(tstate);
+ else {
+ assert(tstate->frame->f_exc_value == NULL);
+ assert(tstate->frame->f_exc_traceback == NULL);
+ }
/* pop frame */
exit_eval_frame:
@@ -2846,6 +2851,7 @@
- Once an exception is caught by an except clause, it is transferred
from tstate->curexc_ZZZ to tstate->exc_ZZZ, from which sys.exc_info()
can pick it up. This is the primary task of set_exc_info().
+ XXX That can't be right: set_exc_info() doesn't look at tstate->curexc_ZZZ.
- Now let me explain the complicated dance with frame->f_exc_ZZZ.
@@ -2900,33 +2906,33 @@
set_exc_info(PyThreadState *tstate,
PyObject *type, PyObject *value, PyObject *tb)
{
- PyFrameObject *frame;
+ PyFrameObject *frame = tstate->frame;
PyObject *tmp_type, *tmp_value, *tmp_tb;
- frame = tstate->frame;
+ assert(type != NULL);
+ assert(frame != NULL);
if (frame->f_exc_type == NULL) {
- /* This frame didn't catch an exception before */
- /* Save previous exception of this thread in this frame */
+ assert(frame->f_exc_value == NULL);
+ assert(frame->f_exc_traceback == NULL);
+ /* This frame didn't catch an exception before. */
+ /* Save previous exception of this thread in this frame. */
if (tstate->exc_type == NULL) {
+ /* XXX Why is this set to Py_None? */
Py_INCREF(Py_None);
tstate->exc_type = Py_None;
}
- tmp_value = frame->f_exc_value;
- tmp_tb = frame->f_exc_traceback;
- Py_XINCREF(tstate->exc_type);
+ Py_INCREF(tstate->exc_type);
Py_XINCREF(tstate->exc_value);
Py_XINCREF(tstate->exc_traceback);
frame->f_exc_type = tstate->exc_type;
frame->f_exc_value = tstate->exc_value;
frame->f_exc_traceback = tstate->exc_traceback;
- Py_XDECREF(tmp_value);
- Py_XDECREF(tmp_tb);
}
- /* Set new exception for this thread */
+ /* Set new exception for this thread. */
tmp_type = tstate->exc_type;
tmp_value = tstate->exc_value;
tmp_tb = tstate->exc_traceback;
- Py_XINCREF(type);
+ Py_INCREF(type);
Py_XINCREF(value);
Py_XINCREF(tb);
tstate->exc_type = type;
@@ -2946,33 +2952,42 @@
{
PyFrameObject *frame;
PyObject *tmp_type, *tmp_value, *tmp_tb;
+
+ /* It's a precondition that the thread state's frame caught an
+ * exception -- verify in a debug build.
+ */
+ assert(tstate != NULL);
frame = tstate->frame;
- if (frame->f_exc_type != NULL) {
- /* This frame caught an exception */
- tmp_type = tstate->exc_type;
- tmp_value = tstate->exc_value;
- tmp_tb = tstate->exc_traceback;
- Py_INCREF(frame->f_exc_type);
- Py_XINCREF(frame->f_exc_value);
- Py_XINCREF(frame->f_exc_traceback);
- tstate->exc_type = frame->f_exc_type;
- tstate->exc_value = frame->f_exc_value;
- tstate->exc_traceback = frame->f_exc_traceback;
- Py_XDECREF(tmp_type);
- Py_XDECREF(tmp_value);
- Py_XDECREF(tmp_tb);
- /* For b/w compatibility */
- PySys_SetObject("exc_type", frame->f_exc_type);
- PySys_SetObject("exc_value", frame->f_exc_value);
- PySys_SetObject("exc_traceback", frame->f_exc_traceback);
- }
+ assert(frame != NULL);
+ assert(frame->f_exc_type != NULL);
+
+ /* Copy the frame's exception info back to the thread state. */
+ tmp_type = tstate->exc_type;
+ tmp_value = tstate->exc_value;
+ tmp_tb = tstate->exc_traceback;
+ Py_INCREF(frame->f_exc_type);
+ Py_XINCREF(frame->f_exc_value);
+ Py_XINCREF(frame->f_exc_traceback);
+ tstate->exc_type = frame->f_exc_type;
+ tstate->exc_value = frame->f_exc_value;
+ tstate->exc_traceback = frame->f_exc_traceback;
+ Py_XDECREF(tmp_type);
+ Py_XDECREF(tmp_value);
+ Py_XDECREF(tmp_tb);
+
+ /* For b/w compatibility */
+ PySys_SetObject("exc_type", frame->f_exc_type);
+ PySys_SetObject("exc_value", frame->f_exc_value);
+ PySys_SetObject("exc_traceback", frame->f_exc_traceback);
+
+ /* Clear the frame's exception info. */
tmp_type = frame->f_exc_type;
tmp_value = frame->f_exc_value;
tmp_tb = frame->f_exc_traceback;
frame->f_exc_type = NULL;
frame->f_exc_value = NULL;
frame->f_exc_traceback = NULL;
- Py_XDECREF(tmp_type);
+ Py_DECREF(tmp_type);
Py_XDECREF(tmp_value);
Py_XDECREF(tmp_tb);
}
@@ -3846,7 +3861,7 @@
Py_ssize_t x;
if (PyInt_Check(v)) {
x = PyInt_AsSsize_t(v);
- }
+ }
else if (v->ob_type->tp_as_number &&
PyType_HasFeature(v->ob_type, Py_TPFLAGS_HAVE_INDEX)
&& v->ob_type->tp_as_number->nb_index) {
@@ -4064,7 +4079,7 @@
result = PyObject_CallFunctionObjArgs(metaclass, name, bases, methods, NULL);
Py_DECREF(metaclass);
if (result == NULL && PyErr_ExceptionMatches(PyExc_TypeError)) {
- /* A type error here likely means that the user passed
+ /* A type error here likely means that the user passed
in a base that was not a class (such the random module
instead of the random.random type). Help them out with
by augmenting the error message with more information.*/
@@ -4204,7 +4219,7 @@
{
/* This function implements 'variable += expr' when both arguments
are strings. */
-
+
if (v->ob_refcnt == 2) {
/* In the common case, there are 2 references to the value
* stored in 'variable' when the += is performed: one on the
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