mirror of https://github.com/python/cpython
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.
This commit is contained in:
Tim Peters
parent
7e0a62ea90
commit
7df5e7f4b2
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@ -26,7 +26,16 @@ typedef struct _frame {
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to the current stack top. */
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PyObject **f_stacktop;
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PyObject *f_trace; /* Trace function */
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/* If an exception is raised in this frame, the next three are used to
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* record the exception info (if any) originally in the thread state. See
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* comments before set_exc_info() -- it's not obvious.
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* Invariant: if _type is NULL, then so are _value and _traceback.
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* Desired invariant: all three are NULL, or all three are non-NULL. That
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* one isn't currently true, but "should be".
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*/
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PyObject *f_exc_type, *f_exc_value, *f_exc_traceback;
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PyThreadState *f_tstate;
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int f_lasti; /* Last instruction if called */
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/* As of 2.3 f_lineno is only valid when tracing is active (i.e. when
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@ -24,7 +24,7 @@
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#pragma optimize("agtw", on)
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#endif
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#ifndef WITH_TSC
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#ifndef WITH_TSC
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#define READ_TIMESTAMP(var)
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@ -49,7 +49,7 @@ ppc_getcounter(uint64 *v)
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asm volatile ("mftbu %0" : "=r" (tbu2));
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if (__builtin_expect(tbu != tbu2, 0)) goto loop;
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/* The slightly peculiar way of writing the next lines is
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/* The slightly peculiar way of writing the next lines is
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compiled better by GCC than any other way I tried. */
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((long*)(v))[0] = tbu;
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((long*)(v))[1] = tb;
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@ -62,7 +62,7 @@ ppc_getcounter(uint64 *v)
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#endif
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void dump_tsc(int opcode, int ticked, uint64 inst0, uint64 inst1,
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void dump_tsc(int opcode, int ticked, uint64 inst0, uint64 inst1,
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uint64 loop0, uint64 loop1, uint64 intr0, uint64 intr1)
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{
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uint64 intr, inst, loop;
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@ -567,7 +567,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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inst0 -- beginning of switch statement for opcode dispatch
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inst1 -- end of switch statement (may be skipped)
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loop0 -- the top of the mainloop
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loop1 -- place where control returns again to top of mainloop
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loop1 -- place where control returns again to top of mainloop
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(may be skipped)
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intr1 -- beginning of long interruption
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intr2 -- end of long interruption
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@ -768,7 +768,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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why = WHY_EXCEPTION;
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goto on_error;
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}
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for (;;) {
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#ifdef WITH_TSC
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if (inst1 == 0) {
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@ -2218,7 +2218,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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re-raising the exception. (But non-local gotos
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should still be resumed.)
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*/
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x = TOP();
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u = SECOND();
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if (PyInt_Check(u) || u == Py_None) {
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@ -2581,7 +2581,12 @@ fast_yield:
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}
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}
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reset_exc_info(tstate);
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if (tstate->frame->f_exc_type != NULL)
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reset_exc_info(tstate);
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else {
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assert(tstate->frame->f_exc_value == NULL);
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assert(tstate->frame->f_exc_traceback == NULL);
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}
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/* pop frame */
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exit_eval_frame:
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@ -2846,6 +2851,7 @@ PyEval_EvalCodeEx(PyCodeObject *co, PyObject *globals, PyObject *locals,
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- Once an exception is caught by an except clause, it is transferred
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from tstate->curexc_ZZZ to tstate->exc_ZZZ, from which sys.exc_info()
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can pick it up. This is the primary task of set_exc_info().
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XXX That can't be right: set_exc_info() doesn't look at tstate->curexc_ZZZ.
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- Now let me explain the complicated dance with frame->f_exc_ZZZ.
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@ -2900,33 +2906,33 @@ Py_LOCAL(void)
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set_exc_info(PyThreadState *tstate,
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PyObject *type, PyObject *value, PyObject *tb)
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{
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PyFrameObject *frame;
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PyFrameObject *frame = tstate->frame;
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PyObject *tmp_type, *tmp_value, *tmp_tb;
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frame = tstate->frame;
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assert(type != NULL);
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assert(frame != NULL);
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if (frame->f_exc_type == NULL) {
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/* This frame didn't catch an exception before */
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/* Save previous exception of this thread in this frame */
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assert(frame->f_exc_value == NULL);
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assert(frame->f_exc_traceback == NULL);
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/* This frame didn't catch an exception before. */
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/* Save previous exception of this thread in this frame. */
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if (tstate->exc_type == NULL) {
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/* XXX Why is this set to Py_None? */
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Py_INCREF(Py_None);
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tstate->exc_type = Py_None;
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}
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tmp_value = frame->f_exc_value;
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tmp_tb = frame->f_exc_traceback;
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Py_XINCREF(tstate->exc_type);
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Py_INCREF(tstate->exc_type);
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Py_XINCREF(tstate->exc_value);
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Py_XINCREF(tstate->exc_traceback);
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frame->f_exc_type = tstate->exc_type;
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frame->f_exc_value = tstate->exc_value;
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frame->f_exc_traceback = tstate->exc_traceback;
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Py_XDECREF(tmp_value);
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Py_XDECREF(tmp_tb);
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}
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/* Set new exception for this thread */
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/* Set new exception for this thread. */
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tmp_type = tstate->exc_type;
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tmp_value = tstate->exc_value;
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tmp_tb = tstate->exc_traceback;
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Py_XINCREF(type);
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Py_INCREF(type);
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Py_XINCREF(value);
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Py_XINCREF(tb);
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tstate->exc_type = type;
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@ -2946,33 +2952,42 @@ reset_exc_info(PyThreadState *tstate)
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{
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PyFrameObject *frame;
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PyObject *tmp_type, *tmp_value, *tmp_tb;
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/* It's a precondition that the thread state's frame caught an
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* exception -- verify in a debug build.
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*/
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assert(tstate != NULL);
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frame = tstate->frame;
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if (frame->f_exc_type != NULL) {
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/* This frame caught an exception */
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tmp_type = tstate->exc_type;
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tmp_value = tstate->exc_value;
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tmp_tb = tstate->exc_traceback;
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Py_INCREF(frame->f_exc_type);
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Py_XINCREF(frame->f_exc_value);
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Py_XINCREF(frame->f_exc_traceback);
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tstate->exc_type = frame->f_exc_type;
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tstate->exc_value = frame->f_exc_value;
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tstate->exc_traceback = frame->f_exc_traceback;
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Py_XDECREF(tmp_type);
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Py_XDECREF(tmp_value);
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Py_XDECREF(tmp_tb);
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/* For b/w compatibility */
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PySys_SetObject("exc_type", frame->f_exc_type);
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PySys_SetObject("exc_value", frame->f_exc_value);
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PySys_SetObject("exc_traceback", frame->f_exc_traceback);
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}
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assert(frame != NULL);
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assert(frame->f_exc_type != NULL);
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/* Copy the frame's exception info back to the thread state. */
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tmp_type = tstate->exc_type;
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tmp_value = tstate->exc_value;
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tmp_tb = tstate->exc_traceback;
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Py_INCREF(frame->f_exc_type);
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Py_XINCREF(frame->f_exc_value);
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Py_XINCREF(frame->f_exc_traceback);
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tstate->exc_type = frame->f_exc_type;
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tstate->exc_value = frame->f_exc_value;
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tstate->exc_traceback = frame->f_exc_traceback;
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Py_XDECREF(tmp_type);
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Py_XDECREF(tmp_value);
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Py_XDECREF(tmp_tb);
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/* For b/w compatibility */
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PySys_SetObject("exc_type", frame->f_exc_type);
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PySys_SetObject("exc_value", frame->f_exc_value);
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PySys_SetObject("exc_traceback", frame->f_exc_traceback);
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/* Clear the frame's exception info. */
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tmp_type = frame->f_exc_type;
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tmp_value = frame->f_exc_value;
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tmp_tb = frame->f_exc_traceback;
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frame->f_exc_type = NULL;
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frame->f_exc_value = NULL;
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frame->f_exc_traceback = NULL;
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Py_XDECREF(tmp_type);
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Py_DECREF(tmp_type);
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Py_XDECREF(tmp_value);
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Py_XDECREF(tmp_tb);
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}
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@ -3846,7 +3861,7 @@ _PyEval_SliceIndex(PyObject *v, Py_ssize_t *pi)
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Py_ssize_t x;
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if (PyInt_Check(v)) {
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x = PyInt_AsSsize_t(v);
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}
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}
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else if (v->ob_type->tp_as_number &&
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PyType_HasFeature(v->ob_type, Py_TPFLAGS_HAVE_INDEX)
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&& v->ob_type->tp_as_number->nb_index) {
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@ -4064,7 +4079,7 @@ build_class(PyObject *methods, PyObject *bases, PyObject *name)
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result = PyObject_CallFunctionObjArgs(metaclass, name, bases, methods, NULL);
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Py_DECREF(metaclass);
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if (result == NULL && PyErr_ExceptionMatches(PyExc_TypeError)) {
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/* A type error here likely means that the user passed
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/* A type error here likely means that the user passed
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in a base that was not a class (such the random module
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instead of the random.random type). Help them out with
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by augmenting the error message with more information.*/
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@ -4204,7 +4219,7 @@ string_concatenate(PyObject *v, PyObject *w,
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{
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/* This function implements 'variable += expr' when both arguments
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are strings. */
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if (v->ob_refcnt == 2) {
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/* In the common case, there are 2 references to the value
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* stored in 'variable' when the += is performed: one on the
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