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GH-98831: Remove all remaining DISPATCH() calls from bytecodes.c #99271

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Merged
merged 8 commits into from
Nov 10, 2022
Merged

GH-98831: Remove all remaining DISPATCH() calls from bytecodes.c #99271

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d453fcc
Remove all remaining DISPATCH() calls from bytecodes.c
gvanrossum Nov 9, 2022
14d60fd
Merge commit 'c7f57087149968e9a72f6dee73514ff18fee78e8' into rm-dispatch
gvanrossum Nov 10, 2022
089b508
Merge commit '2e343fc465ed0206340cf139ba485f9004bbdd41' into rm-dispatch
gvanrossum Nov 10, 2022
3f57751
Merge remote-tracking branch 'origin/main' into rm-dispatch
gvanrossum Nov 10, 2022
f4ebe70
Merge branch 'main' into rm-dispatch
gvanrossum Nov 10, 2022
67200bf
Whitespace/braces from Brandt's review
gvanrossum Nov 10, 2022
a419b2b
Merge remote-tracking branch 'origin/main' into rm-dispatch
gvanrossum Nov 10, 2022
ed64309
Regen cases
gvanrossum Nov 10, 2022
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182 changes: 88 additions & 94 deletions Python/bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,6 @@ do { \
#define JUMPBY(offset) ((void)0)
#define GO_TO_INSTRUCTION(instname) ((void)0)
#define DISPATCH_SAME_OPARG() ((void)0)
#define DISPATCH() ((void)0)

#define inst(name, ...) case name:
#define super(name) static int SUPER_##name
Expand Down Expand Up @@ -104,10 +103,6 @@ dummy_func(
{
switch (opcode) {

/* BEWARE!
It is essential that any operation that fails must goto error
and that all operation that succeed call DISPATCH() ! */

// BEGIN BYTECODES //
inst(NOP, (--)) {
}
Expand Down Expand Up @@ -152,16 +147,14 @@ dummy_func(
super(LOAD_FAST__LOAD_CONST) = LOAD_FAST + LOAD_CONST;
super(STORE_FAST__LOAD_FAST) = STORE_FAST + LOAD_FAST;
super(STORE_FAST__STORE_FAST) = STORE_FAST + STORE_FAST;
super (LOAD_CONST__LOAD_FAST) = LOAD_CONST + LOAD_FAST;
super(LOAD_CONST__LOAD_FAST) = LOAD_CONST + LOAD_FAST;

inst(POP_TOP, (value --)) {
Py_DECREF(value);
}

// stack effect: ( -- __0)
inst(PUSH_NULL) {
/* Use BASIC_PUSH as NULL is not a valid object pointer */
BASIC_PUSH(NULL);
inst(PUSH_NULL, (-- res)) {
res = NULL;
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I feel that this ought to fail, as we should have NULL checks in debug mode.

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Yeah, but we never had those. In debug mode we check for stack overflow/underflow but not for NULL-ness. (Of course the NULL will wreak havoc if it gets popped by the wrong opcode, bu that's also nothing new.) The code generator still checks for stack over/underflow by calling STACK_SHRINK()/GROW(), so nothing is really changed.

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Once we have typed stack effects, we can auto-generate those sorts of assertions. That would be really nice.

}

inst(END_FOR, (value1, value2 --)) {
Expand Down Expand Up @@ -816,11 +809,12 @@ dummy_func(
Py_DECREF(receiver);
SET_TOP(retval);
JUMPBY(oparg);
DISPATCH();
}
assert(gen_status == PYGEN_NEXT);
assert(retval != NULL);
PUSH(retval);
else {
assert(gen_status == PYGEN_NEXT);
assert(retval != NULL);
PUSH(retval);
}
}

// stack effect: ( -- )
Expand Down Expand Up @@ -913,7 +907,6 @@ dummy_func(
if (PyErr_GivenExceptionMatches(val, PyExc_StopAsyncIteration)) {
Py_DECREF(val);
Py_DECREF(POP());
DISPATCH();
}
else {
PyObject *exc = Py_NewRef(PyExceptionInstance_Class(val));
Expand All @@ -935,12 +928,13 @@ dummy_func(
Py_DECREF(POP()); // The last sent value.
Py_DECREF(POP()); // The delegated sub-iterator.
PUSH(value);
DISPATCH();
}
PyObject *exc_type = Py_NewRef(Py_TYPE(exc_value));
PyObject *exc_traceback = PyException_GetTraceback(exc_value);
_PyErr_Restore(tstate, exc_type, Py_NewRef(exc_value), exc_traceback);
goto exception_unwind;
else {
PyObject *exc_type = Py_NewRef(Py_TYPE(exc_value));
PyObject *exc_traceback = PyException_GetTraceback(exc_value);
_PyErr_Restore(tstate, exc_type, Py_NewRef(exc_value), exc_traceback);
goto exception_unwind;
}
}

inst(STOPITERATION_ERROR) {
Expand Down Expand Up @@ -982,7 +976,6 @@ dummy_func(
PyException_SetContext(error, exc);
Py_DECREF(message);
}
DISPATCH();
}


Expand Down Expand Up @@ -1040,8 +1033,7 @@ dummy_func(
goto error;
}

// stack effect: ( -- )
inst(DELETE_NAME) {
inst(DELETE_NAME, (--)) {
PyObject *name = GETITEM(names, oparg);
PyObject *ns = LOCALS();
int err;
Expand All @@ -1051,6 +1043,7 @@ dummy_func(
goto error;
}
err = PyObject_DelItem(ns, name);
// Can't use ERROR_IF here.
if (err != 0) {
format_exc_check_arg(tstate, PyExc_NameError,
NAME_ERROR_MSG,
Expand Down Expand Up @@ -1190,11 +1183,11 @@ dummy_func(
goto error;
}

// stack effect: ( -- )
inst(DELETE_GLOBAL) {
inst(DELETE_GLOBAL, (--)) {
PyObject *name = GETITEM(names, oparg);
int err;
err = PyDict_DelItem(GLOBALS(), name);
// Can't use ERROR_IF here.
if (err != 0) {
if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
format_exc_check_arg(tstate, PyExc_NameError,
Expand Down Expand Up @@ -1374,18 +1367,13 @@ dummy_func(
SET_TOP(Py_NewRef(res));
}

// stack effect: ( -- )
inst(DELETE_FAST) {
inst(DELETE_FAST, (--)) {
PyObject *v = GETLOCAL(oparg);
if (v != NULL) {
SETLOCAL(oparg, NULL);
DISPATCH();
}
goto unbound_local_error;
ERROR_IF(v == NULL, unbound_local_error);
SETLOCAL(oparg, NULL);
}

// stack effect: ( -- )
inst(MAKE_CELL) {
inst(MAKE_CELL, (--)) {
// "initial" is probably NULL but not if it's an arg (or set
// via PyFrame_LocalsToFast() before MAKE_CELL has run).
PyObject *initial = GETLOCAL(oparg);
Expand All @@ -1396,17 +1384,17 @@ dummy_func(
SETLOCAL(oparg, cell);
}

// stack effect: ( -- )
inst(DELETE_DEREF) {
inst(DELETE_DEREF, (--)) {
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
if (oldobj != NULL) {
PyCell_SET(cell, NULL);
Py_DECREF(oldobj);
DISPATCH();
// Can't use ERROR_IF here.
// Fortunately we don't need its superpower.
if (oldobj == NULL) {
format_exc_unbound(tstate, frame->f_code, oparg);
goto error;
}
format_exc_unbound(tstate, frame->f_code, oparg);
goto error;
PyCell_SET(cell, NULL);
Py_DECREF(oldobj);
}

// stack effect: ( -- __0)
Expand Down Expand Up @@ -1769,15 +1757,15 @@ dummy_func(
Py_DECREF(owner);
PUSH(meth);
}
JUMPBY(INLINE_CACHE_ENTRIES_LOAD_ATTR);
DISPATCH();
}
PyObject *res = PyObject_GetAttr(owner, name);
if (res == NULL) {
goto error;
else {
PyObject *res = PyObject_GetAttr(owner, name);
if (res == NULL) {
goto error;
}
Py_DECREF(owner);
SET_TOP(res);
}
Py_DECREF(owner);
SET_TOP(res);
JUMPBY(INLINE_CACHE_ENTRIES_LOAD_ATTR);
}

Expand Down Expand Up @@ -2435,21 +2423,23 @@ dummy_func(
if (Py_IsTrue(cond)) {
STACK_SHRINK(1);
_Py_DECREF_NO_DEALLOC(cond);
DISPATCH();
}
if (Py_IsFalse(cond)) {
else if (Py_IsFalse(cond)) {
JUMPBY(oparg);
DISPATCH();
}
err = PyObject_IsTrue(cond);
if (err > 0) {
STACK_SHRINK(1);
Py_DECREF(cond);
else {
err = PyObject_IsTrue(cond);
if (err > 0) {
STACK_SHRINK(1);
Py_DECREF(cond);
}
else if (err == 0) {
JUMPBY(oparg);
}
else {
goto error;
}
}
else if (err == 0)
JUMPBY(oparg);
else
goto error;
}

// error: JUMP_IF_TRUE_OR_POP stack effect depends on jump flag
Expand All @@ -2459,22 +2449,23 @@ dummy_func(
if (Py_IsFalse(cond)) {
STACK_SHRINK(1);
_Py_DECREF_NO_DEALLOC(cond);
DISPATCH();
}
if (Py_IsTrue(cond)) {
JUMPBY(oparg);
DISPATCH();
}
err = PyObject_IsTrue(cond);
if (err > 0) {
else if (Py_IsTrue(cond)) {
JUMPBY(oparg);
}
else if (err == 0) {
STACK_SHRINK(1);
Py_DECREF(cond);
else {
err = PyObject_IsTrue(cond);
if (err > 0) {
JUMPBY(oparg);
}
else if (err == 0) {
STACK_SHRINK(1);
Py_DECREF(cond);
}
else {
goto error;
}
}
else
goto error;
}

// stack effect: ( -- )
Expand Down Expand Up @@ -2615,23 +2606,24 @@ dummy_func(
if (next != NULL) {
PUSH(next);
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER);
DISPATCH();
}
if (_PyErr_Occurred(tstate)) {
if (!_PyErr_ExceptionMatches(tstate, PyExc_StopIteration)) {
goto error;
}
else if (tstate->c_tracefunc != NULL) {
call_exc_trace(tstate->c_tracefunc, tstate->c_traceobj, tstate, frame);
else {
if (_PyErr_Occurred(tstate)) {
if (!_PyErr_ExceptionMatches(tstate, PyExc_StopIteration)) {
goto error;
}
else if (tstate->c_tracefunc != NULL) {
call_exc_trace(tstate->c_tracefunc, tstate->c_traceobj, tstate, frame);
}
_PyErr_Clear(tstate);
}
_PyErr_Clear(tstate);
/* iterator ended normally */
assert(_Py_OPCODE(next_instr[INLINE_CACHE_ENTRIES_FOR_ITER + oparg]) == END_FOR);
STACK_SHRINK(1);
Py_DECREF(iter);
/* Skip END_FOR */
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 1);
}
/* iterator ended normally */
assert(_Py_OPCODE(next_instr[INLINE_CACHE_ENTRIES_FOR_ITER + oparg]) == END_FOR);
STACK_SHRINK(1);
Py_DECREF(iter);
/* Skip END_FOR */
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 1);
}

// stack effect: ( -- __0)
Expand All @@ -2646,14 +2638,15 @@ dummy_func(
PyObject *next = PyList_GET_ITEM(seq, it->it_index++);
PUSH(Py_NewRef(next));
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER);
DISPATCH();
goto end_for_iter_list; // End of this instruction
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:(

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Yeah, I'm really counting on the compiler to optimize this for us.

}
it->it_seq = NULL;
Py_DECREF(seq);
}
STACK_SHRINK(1);
Py_DECREF(it);
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 1);
end_for_iter_list:
}

// stack effect: ( -- __0)
Expand All @@ -2668,15 +2661,16 @@ dummy_func(
STACK_SHRINK(1);
Py_DECREF(r);
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 1);
DISPATCH();
}
long value = (long)(r->start +
(unsigned long)(r->index++) * r->step);
if (_PyLong_AssignValue(&GETLOCAL(_Py_OPARG(next)), value) < 0) {
goto error;
else {
long value = (long)(r->start +
(unsigned long)(r->index++) * r->step);
if (_PyLong_AssignValue(&GETLOCAL(_Py_OPARG(next)), value) < 0) {
goto error;
}
// The STORE_FAST is already done.
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + 1);
}
// The STORE_FAST is already done.
JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + 1);
}

inst(FOR_ITER_GEN) {
Expand Down
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