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bpo-46372: Try to mutate the LHS during fast float ops #30594

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bpo-46372: Try to mutate the LHS during fast float ops #30594

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cf64e13
Perform specialized ops in-place when possible
brandtbucher Jan 11, 2022
5e49a13
Break out common logic
brandtbucher Jan 12, 2022
f7187d9
Clean things up a bit
brandtbucher Jan 12, 2022
dd19cec
Clean up macro
brandtbucher Jan 12, 2022
78cc5c4
Simplify the "small" int case
brandtbucher Jan 13, 2022
218b10b
blurb add
brandtbucher Jan 14, 2022
505fd8e
Catch up with main
brandtbucher Jan 18, 2022
6b4cc6d
Apply first round of code revew comments
brandtbucher Jan 18, 2022
f21a813
Fix 32-bit Windows errrors
brandtbucher Jan 19, 2022
d6a69d5
Perform the inplace checks when specializing
brandtbucher Jan 19, 2022
f11cf6d
Remove duplicate code
brandtbucher Jan 19, 2022
b6f041a
Simplify things further
brandtbucher Jan 19, 2022
eb586b1
Remove int and refcount == 2 optimizations
brandtbucher Jan 19, 2022
def9c64
Catch up with main
brandtbucher Jan 21, 2022
6e262ba
Revert int changes
brandtbucher Jan 24, 2022
37fab55
Catch up with main
brandtbucher Jan 28, 2022
04f186c
Add the "adaptive superinstructions" back
brandtbucher Feb 1, 2022
e0d0042
Catch up with main
brandtbucher Feb 1, 2022
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112 changes: 57 additions & 55 deletions Include/opcode.h
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2 changes: 2 additions & 0 deletions Lib/opcode.py
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,8 @@ def jabs_op(name, op):
"BINARY_OP_ADD_FLOAT",
"BINARY_OP_ADD_UNICODE",
"BINARY_OP_INPLACE_ADD_UNICODE",
"BINARY_OP_INPLACE_ADD_FLOAT",
"BINARY_OP_INPLACE_SUBTRACT_FLOAT",
"BINARY_OP_MULTIPLY_INT",
"BINARY_OP_MULTIPLY_FLOAT",
"BINARY_OP_SUBTRACT_INT",
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-01-13-22-50-49.bpo-46372.b00Vdn.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Improve the performance of specialized :class:`float`
operations by mutating the left operand in-place when it is safe to do so.
98 changes: 48 additions & 50 deletions Python/ceval.c
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Original file line number Diff line number Diff line change
Expand Up @@ -857,6 +857,43 @@ static const binaryfunc binary_ops[] = {
[NB_INPLACE_XOR] = PyNumber_InPlaceXor,
};

// NOTE: INPLACE must be a compile-time constant to avoid runtime branching!
#define BINARY_OP_FAST_FLOAT(OP, INPLACE) \
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I'm not a fan of giant macros and I don't like the hidden compile time control flow.
Given that the inplace and non-inplace forms specialized forms differ in a fundamental way, I'd like that to be explicit in the instructions themselves.

Maybe have two different macros, one for the inplace form and one for the non-inplace form.
You should be able to factor out some of the common code into helper macros.
That might be clearer. Up to you.

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Makes sense. I'll go ahead and split it up.

do { \
assert(cframe.use_tracing == 0); \
PyObject *lhs = SECOND(); \
PyObject *rhs = TOP(); \
DEOPT_IF(!PyFloat_CheckExact(lhs), BINARY_OP); \
DEOPT_IF(!PyFloat_CheckExact(rhs), BINARY_OP); \
if (INPLACE) { \
assert(_Py_OPCODE(*next_instr) == STORE_FAST || \
_Py_OPCODE(*next_instr) == STORE_FAST__LOAD_FAST); \
DEOPT_IF(GETLOCAL(_Py_OPARG(*next_instr)) != lhs, BINARY_OP); \
} \
STAT_INC(BINARY_OP, hit); \
double l = PyFloat_AS_DOUBLE(lhs); \
double r = PyFloat_AS_DOUBLE(rhs); \
double d = l OP r; \
STACK_SHRINK(1); \
Py_DECREF(rhs); \
if (Py_REFCNT(lhs) == 1 + !!(INPLACE)) { \
if (INPLACE) { \
Py_DECREF(lhs); \
STACK_SHRINK(1); \
next_instr++; \
} \
PyFloat_AS_DOUBLE(lhs) = d; \
NOTRACE_DISPATCH(); \
} \
Py_DECREF(lhs); \
PyObject *res = PyFloat_FromDouble(d); \
SET_TOP(res); \
if (res == NULL) { \
goto error; \
} \
NOTRACE_DISPATCH(); \
} while (0)


// PEP 634: Structural Pattern Matching

Expand Down Expand Up @@ -1986,23 +2023,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
}

TARGET(BINARY_OP_MULTIPLY_FLOAT) {
assert(cframe.use_tracing == 0);
PyObject *left = SECOND();
PyObject *right = TOP();
DEOPT_IF(!PyFloat_CheckExact(left), BINARY_OP);
DEOPT_IF(!PyFloat_CheckExact(right), BINARY_OP);
STAT_INC(BINARY_OP, hit);
double dprod = ((PyFloatObject *)left)->ob_fval *
((PyFloatObject *)right)->ob_fval;
PyObject *prod = PyFloat_FromDouble(dprod);
SET_SECOND(prod);
Py_DECREF(right);
Py_DECREF(left);
STACK_SHRINK(1);
if (prod == NULL) {
goto error;
}
NOTRACE_DISPATCH();
BINARY_OP_FAST_FLOAT(*, false);
}

TARGET(BINARY_OP_SUBTRACT_INT) {
Expand All @@ -2024,22 +2045,11 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
}

TARGET(BINARY_OP_SUBTRACT_FLOAT) {
assert(cframe.use_tracing == 0);
PyObject *left = SECOND();
PyObject *right = TOP();
DEOPT_IF(!PyFloat_CheckExact(left), BINARY_OP);
DEOPT_IF(!PyFloat_CheckExact(right), BINARY_OP);
STAT_INC(BINARY_OP, hit);
double dsub = ((PyFloatObject *)left)->ob_fval - ((PyFloatObject *)right)->ob_fval;
PyObject *sub = PyFloat_FromDouble(dsub);
SET_SECOND(sub);
Py_DECREF(right);
Py_DECREF(left);
STACK_SHRINK(1);
if (sub == NULL) {
goto error;
}
NOTRACE_DISPATCH();
BINARY_OP_FAST_FLOAT(-, false);
}

TARGET(BINARY_OP_INPLACE_SUBTRACT_FLOAT) {
BINARY_OP_FAST_FLOAT(-, true);
}

TARGET(BINARY_OP_ADD_UNICODE) {
Expand Down Expand Up @@ -2090,23 +2100,11 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
}

TARGET(BINARY_OP_ADD_FLOAT) {
assert(cframe.use_tracing == 0);
PyObject *left = SECOND();
PyObject *right = TOP();
DEOPT_IF(!PyFloat_CheckExact(left), BINARY_OP);
DEOPT_IF(Py_TYPE(right) != Py_TYPE(left), BINARY_OP);
STAT_INC(BINARY_OP, hit);
double dsum = ((PyFloatObject *)left)->ob_fval +
((PyFloatObject *)right)->ob_fval;
PyObject *sum = PyFloat_FromDouble(dsum);
SET_SECOND(sum);
Py_DECREF(right);
Py_DECREF(left);
STACK_SHRINK(1);
if (sum == NULL) {
goto error;
}
NOTRACE_DISPATCH();
BINARY_OP_FAST_FLOAT(+, false);
}

TARGET(BINARY_OP_INPLACE_ADD_FLOAT) {
BINARY_OP_FAST_FLOAT(+, true);
}

TARGET(BINARY_OP_ADD_INT) {
Expand Down
48 changes: 24 additions & 24 deletions Python/opcode_targets.h
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