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bpo-29988: Only check evalbreaker after calls and on backwards egdes. #18334

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Merged
merged 1 commit into from
Mar 24, 2021
Merged

bpo-29988: Only check evalbreaker after calls and on backwards egdes. #18334

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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-02-03-13-23-10.bpo-29988.8_UB5w.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Only handle asynchronous exceptions and requests to drop the GIL when
returning from a call or on the back edges of loops. Makes sure that
:meth:`__exit__` is always called in with statements, even for interrupts.
83 changes: 37 additions & 46 deletions Python/ceval.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1331,7 +1331,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
TARGET_##op

#ifdef LLTRACE
#define FAST_DISPATCH() \
#define DISPATCH() \
{ \
if (!lltrace && !_Py_TracingPossible(ceval2) && !PyDTrace_LINE_ENABLED()) { \
f->f_lasti = INSTR_OFFSET(); \
Expand All @@ -1341,7 +1341,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
goto fast_next_opcode; \
}
#else
#define FAST_DISPATCH() \
#define DISPATCH() \
{ \
if (!_Py_TracingPossible(ceval2) && !PyDTrace_LINE_ENABLED()) { \
f->f_lasti = INSTR_OFFSET(); \
Expand All @@ -1352,20 +1352,17 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
}
#endif

#define DISPATCH() \
{ \
if (!_Py_atomic_load_relaxed(eval_breaker)) { \
FAST_DISPATCH(); \
} \
continue; \
}

#else
#define TARGET(op) op
#define FAST_DISPATCH() goto fast_next_opcode
#define DISPATCH() continue
#define DISPATCH() goto fast_next_opcode

#endif

#define CHECK_EVAL_BREAKER() \
if (_Py_atomic_load_relaxed(eval_breaker)) { \
continue; \
}


/* Tuple access macros */

Expand Down Expand Up @@ -1857,7 +1854,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
and that all operation that succeed call [FAST_]DISPATCH() ! */

case TARGET(NOP): {
FAST_DISPATCH();
DISPATCH();
}

case TARGET(LOAD_FAST): {
Expand All @@ -1870,36 +1867,36 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
}
Py_INCREF(value);
PUSH(value);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(LOAD_CONST): {
PREDICTED(LOAD_CONST);
PyObject *value = GETITEM(consts, oparg);
Py_INCREF(value);
PUSH(value);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(STORE_FAST): {
PREDICTED(STORE_FAST);
PyObject *value = POP();
SETLOCAL(oparg, value);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(POP_TOP): {
PyObject *value = POP();
Py_DECREF(value);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(ROT_TWO): {
PyObject *top = TOP();
PyObject *second = SECOND();
SET_TOP(second);
SET_SECOND(top);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(ROT_THREE): {
Expand All @@ -1909,7 +1906,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
SET_TOP(second);
SET_SECOND(third);
SET_THIRD(top);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(ROT_FOUR): {
Expand All @@ -1921,14 +1918,14 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
SET_SECOND(third);
SET_THIRD(fourth);
SET_FOURTH(top);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(DUP_TOP): {
PyObject *top = TOP();
Py_INCREF(top);
PUSH(top);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(DUP_TOP_TWO): {
Expand All @@ -1939,7 +1936,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
STACK_GROW(2);
SET_TOP(top);
SET_SECOND(second);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(UNARY_POSITIVE): {
Expand Down Expand Up @@ -2704,7 +2701,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
UNWIND_EXCEPT_HANDLER(b);
Py_DECREF(POP());
JUMPBY(oparg);
FAST_DISPATCH();
DISPATCH();
}
else {
PyObject *val = POP();
Expand All @@ -2718,7 +2715,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
PyObject *value = PyExc_AssertionError;
Py_INCREF(value);
PUSH(value);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(LOAD_BUILD_CLASS): {
Expand Down Expand Up @@ -3620,7 +3617,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
Py_DECREF(right);
PREDICT(POP_JUMP_IF_FALSE);
PREDICT(POP_JUMP_IF_TRUE);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(CONTAINS_OP): {
Expand All @@ -3637,7 +3634,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
PUSH(b);
PREDICT(POP_JUMP_IF_FALSE);
PREDICT(POP_JUMP_IF_TRUE);
FAST_DISPATCH();
DISPATCH();
}

#define CANNOT_CATCH_MSG "catching classes that do not inherit from "\
Expand Down Expand Up @@ -3734,7 +3731,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)

case TARGET(JUMP_FORWARD): {
JUMPBY(oparg);
FAST_DISPATCH();
DISPATCH();
}

case TARGET(POP_JUMP_IF_FALSE): {
Expand All @@ -3743,12 +3740,12 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
int err;
if (cond == Py_True) {
Py_DECREF(cond);
FAST_DISPATCH();
DISPATCH();
}
if (cond == Py_False) {
Py_DECREF(cond);
JUMPTO(oparg);
FAST_DISPATCH();
DISPATCH();
}
err = PyObject_IsTrue(cond);
Py_DECREF(cond);
Expand All @@ -3767,12 +3764,12 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
int err;
if (cond == Py_False) {
Py_DECREF(cond);
FAST_DISPATCH();
DISPATCH();
}
if (cond == Py_True) {
Py_DECREF(cond);
JUMPTO(oparg);
FAST_DISPATCH();
DISPATCH();
}
err = PyObject_IsTrue(cond);
Py_DECREF(cond);
Expand All @@ -3792,11 +3789,11 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
if (cond == Py_True) {
STACK_SHRINK(1);
Py_DECREF(cond);
FAST_DISPATCH();
DISPATCH();
}
if (cond == Py_False) {
JUMPTO(oparg);
FAST_DISPATCH();
DISPATCH();
}
err = PyObject_IsTrue(cond);
if (err > 0) {
Expand All @@ -3816,11 +3813,11 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
if (cond == Py_False) {
STACK_SHRINK(1);
Py_DECREF(cond);
FAST_DISPATCH();
DISPATCH();
}
if (cond == Py_True) {
JUMPTO(oparg);
FAST_DISPATCH();
DISPATCH();
}
err = PyObject_IsTrue(cond);
if (err > 0) {
Expand All @@ -3838,18 +3835,8 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
case TARGET(JUMP_ABSOLUTE): {
PREDICTED(JUMP_ABSOLUTE);
JUMPTO(oparg);
#if FAST_LOOPS
/* Enabling this path speeds-up all while and for-loops by bypassing
the per-loop checks for signals. By default, this should be turned-off
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 FAST_DISPATCH).
*/
FAST_DISPATCH();
#else
CHECK_EVAL_BREAKER();
DISPATCH();
#endif
}

case TARGET(GET_LEN): {
Expand Down Expand Up @@ -4260,6 +4247,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
PUSH(res);
if (res == NULL)
goto error;
CHECK_EVAL_BREAKER();
DISPATCH();
}

Expand All @@ -4273,6 +4261,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
if (res == NULL) {
goto error;
}
CHECK_EVAL_BREAKER();
DISPATCH();
}

Expand All @@ -4292,6 +4281,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
if (res == NULL) {
goto error;
}
CHECK_EVAL_BREAKER();
DISPATCH();
}

Expand Down Expand Up @@ -4338,6 +4328,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
if (result == NULL) {
goto error;
}
CHECK_EVAL_BREAKER();
DISPATCH();
}

Expand Down