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GH-130415: Narrow int to 0 based on boolean tests (GH-130772)

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Klaus117 2025-03-04 12:44:09 -08:00 • committed by GitHub
parent e20e47dda6
commit c989e74446
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6 changed files with 38 additions and 2 deletions
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31
Lib/test/test_capi/test_opt.py
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@ -1499,6 +1499,37 @@ class TestUopsOptimization(unittest.TestCase):
# But all of the appends we care about are still there:
self.assertEqual(uops.count("_CALL_LIST_APPEND"), len("ABCDEFG"))
def test_narrow_type_to_constant_int_zero(self):
def f(n):
trace = []
for i in range(n):
# zero is always (int) 0, but we can only prove that it's a integer:
false = i == TIER2_THRESHOLD # this will always be false, while hopefully still fooling optimizer improvements
zero = false + 0 # this should always set the variable zero equal to 0
trace.append("A")
if not zero: # Kept.
trace.append("B")
if not zero: # Removed!
trace.append("C")
trace.append("D")
if zero: # Removed!
trace.append("X")
trace.append("E")
trace.append("F")
if zero: # Removed!
trace.append("X")
trace.append("G")
return trace
trace, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
self.assertEqual(trace, list("ABCDEFG") * TIER2_THRESHOLD)
self.assertIsNotNone(ex)
uops = get_opnames(ex)
# Only one guard remains:
self.assertEqual(uops.count("_GUARD_IS_FALSE_POP"), 1)
self.assertEqual(uops.count("_GUARD_IS_TRUE_POP"), 0)
# But all of the appends we care about are still there:
self.assertEqual(uops.count("_CALL_LIST_APPEND"), len("ABCDEFG"))
def global_identity(x):
return x

1
Misc/ACKS
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@ -1061,6 +1061,7 @@ Detlef Lannert
Rémi Lapeyre
Soren Larsen
Amos Latteier
Keenan Lau
Piers Lauder
Ben Laurie
Yoni Lavi

1
Misc/NEWS.d/next/Core_and_Builtins/2025-03-03-01-21-04.gh-issue-130415.ibOV6B.rst Normal file
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@ -0,0 +1 @@
Improve JIT understanding of integers in boolean context.

2
Python/optimizer_bytecodes.c
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@ -406,7 +406,7 @@ dummy_func(void) {
op(_TO_BOOL_INT, (value -- res)) {
if (!optimize_to_bool(this_instr, ctx, value, &res)) {
sym_set_type(value, &PyLong_Type);
res = sym_new_type(ctx, &PyBool_Type);
res = sym_new_truthiness(ctx, value, true);
}
}

2
Python/optimizer_cases.c.h generated
View file

@ -178,7 +178,7 @@
value = stack_pointer[-1];
if (!optimize_to_bool(this_instr, ctx, value, &res)) {
sym_set_type(value, &PyLong_Type);
res = sym_new_type(ctx, &PyBool_Type);
res = sym_new_truthiness(ctx, value, true);
}
stack_pointer[-1] = res;
break;

3
Python/optimizer_symbols.c
View file

@ -299,6 +299,9 @@ _Py_uop_sym_set_const(JitOptContext *ctx, JitOptSymbol *sym, PyObject *const_val
else if (type == &PyBool_Type) {
_Py_uop_sym_set_const(ctx, value, Py_False);
}
else if (type == &PyLong_Type) {
_Py_uop_sym_set_const(ctx, value, Py_GetConstant(Py_CONSTANT_ZERO));
}
// TODO: More types (GH-130415)!
make_const(sym, const_val);
return;