[Python-checkins] bpo-47053: Reduce deoptimization in BINARY_OP_INPLACE_ADD_UNICODE (GH-31318)

Fri Mar 25 12:13:28 EDT 2022

https://github.com/python/cpython/commit/cca43b7d64f47ea921d0f7a347ae1a839c5463c3
commit: cca43b7d64f47ea921d0f7a347ae1a839c5463c3
branch: main
author: Dennis Sweeney <36520290+sweeneyde at users.noreply.github.com>
committer: markshannon <mark at hotpy.org>
date: 2022年03月25日T16:13:19Z
summary:
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
files:
A Misc/NEWS.d/next/Core and Builtins/2022-03-17-22-47-29.bpo-47053.QAXk8Q.rst
M Include/internal/pycore_code.h
M Python/ceval.c
M Python/specialize.c

diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
index 82dc9e4bdc62f..0f6613b6c1e3d 100644
--- a/Include/internal/pycore_code.h
+++ b/Include/internal/pycore_code.h
@@ -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,
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-03-17-22-47-29.bpo-47053.QAXk8Q.rst b/Misc/NEWS.d/next/Core and Builtins/2022-03-17-22-47-29.bpo-47053.QAXk8Q.rst
new file mode 100644
index 0000000000000..097105b1c20f4
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-03-17-22-47-29.bpo-47053.QAXk8Q.rst	
@@ -0,0 +1 @@
+Reduce de-optimization in the specialized ``BINARY_OP_INPLACE_ADD_UNICODE`` opcode.
diff --git a/Python/ceval.c b/Python/ceval.c
index e1d961fee6a83..4824b192f4e48 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2002,10 +2002,10 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
 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 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
 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 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
 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 {
diff --git a/Python/specialize.c b/Python/specialize.c
index ce091a2c5f078..720bc7f241586 100644
--- a/Python/specialize.c
+++ b/Python/specialize.c
@@ -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;
 }
