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bpo-47053: Reduce deoptimization in BINARY_OP_INPLACE_ADD_UNICODE (GH-31318) 

* Don't deopt if refcounts are too big

* Detect more at specialization time
This commit is contained in:
Dennis Sweeney 2022-03-25 12:13:19 -04:00 committed by GitHub
parent d7163bb35d
commit cca43b7d64
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 11 additions and 7 deletions
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2
Include/internal/pycore_code.h
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@ -263,7 +263,7 @@ extern int _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr,
extern int _Py_Specialize_Precall(PyObject *callable, _Py_CODEUNIT *instr,
int nargs, PyObject *kwnames, int oparg);
extern void _Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
int oparg);
int oparg, PyObject **locals);
extern void _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs,
_Py_CODEUNIT *instr, int oparg);
extern void _Py_Specialize_UnpackSequence(PyObject *seq, _Py_CODEUNIT *instr,

1
Misc/NEWS.d/next/Core and Builtins/2022-03-17-22-47-29.bpo-47053.QAXk8Q.rst Normal file
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@ -0,0 +1 @@
Reduce de-optimization in the specialized ``BINARY_OP_INPLACE_ADD_UNICODE`` opcode.

9
Python/ceval.c
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@ -2002,10 +2002,10 @@ handle_eval_breaker:
PyObject *right = TOP();
DEOPT_IF(!PyUnicode_CheckExact(left), BINARY_OP);
DEOPT_IF(Py_TYPE(right) != Py_TYPE(left), BINARY_OP);
DEOPT_IF(Py_REFCNT(left) != 2, BINARY_OP);
_Py_CODEUNIT true_next = next_instr[INLINE_CACHE_ENTRIES_BINARY_OP];
int next_oparg = _Py_OPARG(true_next);
assert(_Py_OPCODE(true_next) == STORE_FAST);
assert(_Py_OPCODE(true_next) == STORE_FAST ||
_Py_OPCODE(true_next) == STORE_FAST__LOAD_FAST);
/* In the common case, there are 2 references to the value
* stored in 'variable' when the v = v + ... is performed: one
* on the value stack (in 'v') and one still stored in the
@ -2016,7 +2016,8 @@ handle_eval_breaker:
DEOPT_IF(var != left, BINARY_OP);
STAT_INC(BINARY_OP, hit);
GETLOCAL(next_oparg) = NULL;
Py_DECREF(left);
assert(Py_REFCNT(left) >= 2);
Py_DECREF(left); // XXX never need to dealloc
STACK_SHRINK(1);
PyUnicode_Append(&TOP(), right);
Py_DECREF(right);
@ -5378,7 +5379,7 @@ handle_eval_breaker:
PyObject *lhs = SECOND();
PyObject *rhs = TOP();
next_instr--;
_Py_Specialize_BinaryOp(lhs, rhs, next_instr, oparg);
_Py_Specialize_BinaryOp(lhs, rhs, next_instr, oparg, &GETLOCAL(0));
DISPATCH();
}
else {

6
Python/specialize.c
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@ -1742,7 +1742,7 @@ binary_op_fail_kind(int oparg, PyObject *lhs, PyObject *rhs)
void
_Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
int oparg)
int oparg, PyObject **locals)
{
assert(_PyOpcode_Caches[BINARY_OP] == INLINE_CACHE_ENTRIES_BINARY_OP);
_PyBinaryOpCache *cache = (_PyBinaryOpCache *)(instr + 1);
@ -1754,7 +1754,9 @@ _Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
}
if (PyUnicode_CheckExact(lhs)) {
_Py_CODEUNIT next = instr[INLINE_CACHE_ENTRIES_BINARY_OP + 1];
if (_Py_OPCODE(next) == STORE_FAST && Py_REFCNT(lhs) == 2) {
bool to_store = (_Py_OPCODE(next) == STORE_FAST ||
_Py_OPCODE(next) == STORE_FAST__LOAD_FAST);
if (to_store && locals[_Py_OPARG(next)] == lhs) {
_Py_SET_OPCODE(*instr, BINARY_OP_INPLACE_ADD_UNICODE);
goto success;
}