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gh-116088: Insert bottom checks after all sym_set_...() calls (#116089) 

This changes the `sym_set_...()` functions to return a `bool` which is `false`
when the symbol is `bottom` after the operation.

All calls to such functions now check this result and go to `hit_bottom`,
a special error label that prints a different message and then reports
that it wasn't able to optimize the trace. No executor will be produced
in this case.
This commit is contained in:
Guido van Rossum 2024-02-29 10:55:29 -08:00 committed by GitHub
parent 3b6f4cadf1
commit 0656509033
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
7 changed files with 106 additions and 47 deletions
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8
Include/internal/pycore_optimizer.h
View File

@ -91,10 +91,10 @@ extern _Py_UopsSymbol *_Py_uop_sym_new_type(
extern _Py_UopsSymbol *_Py_uop_sym_new_const(_Py_UOpsContext *ctx, PyObject *const_val);
extern _Py_UopsSymbol *_Py_uop_sym_new_null(_Py_UOpsContext *ctx);
extern bool _Py_uop_sym_matches_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
extern void _Py_uop_sym_set_null(_Py_UopsSymbol *sym);
extern void _Py_uop_sym_set_non_null(_Py_UopsSymbol *sym);
extern void _Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
extern void _Py_uop_sym_set_const(_Py_UopsSymbol *sym, PyObject *const_val);
extern bool _Py_uop_sym_set_null(_Py_UopsSymbol *sym);
extern bool _Py_uop_sym_set_non_null(_Py_UopsSymbol *sym);
extern bool _Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *typ);
extern bool _Py_uop_sym_set_const(_Py_UopsSymbol *sym, PyObject *const_val);
extern bool _Py_uop_sym_is_bottom(_Py_UopsSymbol *sym);

24
Lib/test/test_capi/test_opt.py
View File

@ -894,23 +894,33 @@ class TestUopsOptimization(unittest.TestCase):
def test_type_inconsistency(self):
ns = {}
exec(textwrap.dedent("""
src = textwrap.dedent("""
def testfunc(n):
for i in range(n):
x = _test_global + _test_global
"""), globals(), ns)
""")
exec(src, ns, ns)
testfunc = ns['testfunc']
# Must be a real global else it won't be optimized to _LOAD_CONST_INLINE
global _test_global
_test_global = 0
ns['_test_global'] = 0
_, ex = self._run_with_optimizer(testfunc, 16)
self.assertIsNone(ex)
_test_global = 1.2
ns['_test_global'] = 1
_, ex = self._run_with_optimizer(testfunc, 16)
self.assertIsNotNone(ex)
uops = get_opnames(ex)
self.assertIn("_GUARD_BOTH_INT", uops)
self.assertNotIn("_GUARD_BOTH_INT", uops)
self.assertIn("_BINARY_OP_ADD_INT", uops)
# Try again, but between the runs, set the global to a float.
# This should result in no executor the second time.
ns = {}
exec(src, ns, ns)
testfunc = ns['testfunc']
ns['_test_global'] = 0
_, ex = self._run_with_optimizer(testfunc, 16)
self.assertIsNone(ex)
ns['_test_global'] = 3.14
_, ex = self._run_with_optimizer(testfunc, 16)
self.assertIsNone(ex)
if __name__ == "__main__":

9
Python/optimizer_analysis.c
View File

@ -363,6 +363,15 @@ error:
DPRINTF(1, "Encountered error in abstract interpreter\n");
_Py_uop_abstractcontext_fini(ctx);
return 0;
hit_bottom:
// Attempted to push a "bottom" (contradition) symbol onto the stack.
// This means that the abstract interpreter has hit unreachable code.
// We *could* generate an _EXIT_TRACE or _FATAL_ERROR here, but it's
// simpler to just admit failure and not create the executor.
DPRINTF(1, "Hit bottom in abstract interpreter\n");
_Py_uop_abstractcontext_fini(ctx);
return 0;
}

36
Python/optimizer_bytecodes.c
View File

@ -85,8 +85,12 @@ dummy_func(void) {
sym_matches_type(right, &PyLong_Type)) {
REPLACE_OP(this_instr, _NOP, 0, 0);
}
sym_set_type(left, &PyLong_Type);
sym_set_type(right, &PyLong_Type);
if (!sym_set_type(left, &PyLong_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyLong_Type)) {
goto hit_bottom;
}
}
op(_GUARD_BOTH_FLOAT, (left, right -- left, right)) {
@ -94,8 +98,12 @@ dummy_func(void) {
sym_matches_type(right, &PyFloat_Type)) {
REPLACE_OP(this_instr, _NOP, 0 ,0);
}
sym_set_type(left, &PyFloat_Type);
sym_set_type(right, &PyFloat_Type);
if (!sym_set_type(left, &PyFloat_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyFloat_Type)) {
goto hit_bottom;
}
}
op(_GUARD_BOTH_UNICODE, (left, right -- left, right)) {
@ -103,8 +111,12 @@ dummy_func(void) {
sym_matches_type(right, &PyUnicode_Type)) {
REPLACE_OP(this_instr, _NOP, 0 ,0);
}
sym_set_type(left, &PyUnicode_Type);
sym_set_type(right, &PyUnicode_Type);
if (!sym_set_type(left, &PyUnicode_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyUnicode_Type)) {
goto hit_bottom;
}
}
op(_BINARY_OP_ADD_INT, (left, right -- res)) {
@ -365,14 +377,20 @@ dummy_func(void) {
op(_CHECK_FUNCTION_EXACT_ARGS, (func_version/2, callable, self_or_null, unused[oparg] -- callable, self_or_null, unused[oparg])) {
sym_set_type(callable, &PyFunction_Type);
if (!sym_set_type(callable, &PyFunction_Type)) {
goto hit_bottom;
}
(void)self_or_null;
(void)func_version;
}
op(_CHECK_CALL_BOUND_METHOD_EXACT_ARGS, (callable, null, unused[oparg] -- callable, null, unused[oparg])) {
sym_set_null(null);
sym_set_type(callable, &PyMethod_Type);
if (!sym_set_null(null)) {
goto hit_bottom;
}
if (!sym_set_type(callable, &PyMethod_Type)) {
goto hit_bottom;
}
}
op(_INIT_CALL_PY_EXACT_ARGS, (callable, self_or_null, args[oparg] -- new_frame: _Py_UOpsAbstractFrame *)) {

36
Python/optimizer_cases.c.h generated
View File

@ -172,8 +172,12 @@
sym_matches_type(right, &PyLong_Type)) {
REPLACE_OP(this_instr, _NOP, 0, 0);
}
sym_set_type(left, &PyLong_Type);
sym_set_type(right, &PyLong_Type);
if (!sym_set_type(left, &PyLong_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyLong_Type)) {
goto hit_bottom;
}
break;
}
@ -276,8 +280,12 @@
sym_matches_type(right, &PyFloat_Type)) {
REPLACE_OP(this_instr, _NOP, 0 ,0);
}
sym_set_type(left, &PyFloat_Type);
sym_set_type(right, &PyFloat_Type);
if (!sym_set_type(left, &PyFloat_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyFloat_Type)) {
goto hit_bottom;
}
break;
}
@ -383,8 +391,12 @@
sym_matches_type(right, &PyUnicode_Type)) {
REPLACE_OP(this_instr, _NOP, 0 ,0);
}
sym_set_type(left, &PyUnicode_Type);
sym_set_type(right, &PyUnicode_Type);
if (!sym_set_type(left, &PyUnicode_Type)) {
goto hit_bottom;
}
if (!sym_set_type(right, &PyUnicode_Type)) {
goto hit_bottom;
}
break;
}
@ -1397,8 +1409,12 @@
_Py_UopsSymbol *callable;
null = stack_pointer[-1 - oparg];
callable = stack_pointer[-2 - oparg];
sym_set_null(null);
sym_set_type(callable, &PyMethod_Type);
if (!sym_set_null(null)) {
goto hit_bottom;
}
if (!sym_set_type(callable, &PyMethod_Type)) {
goto hit_bottom;
}
break;
}
@ -1425,7 +1441,9 @@
self_or_null = stack_pointer[-1 - oparg];
callable = stack_pointer[-2 - oparg];
uint32_t func_version = (uint32_t)this_instr->operand;
sym_set_type(callable, &PyFunction_Type);
if (!sym_set_type(callable, &PyFunction_Type)) {
goto hit_bottom;
}
(void)self_or_null;
(void)func_version;
break;

36
Python/optimizer_symbols.c
View File

@ -113,60 +113,68 @@ _Py_uop_sym_get_const(_Py_UopsSymbol *sym)
return sym->const_val;
}
void
bool
_Py_uop_sym_set_type(_Py_UopsSymbol *sym, PyTypeObject *typ)
{
assert(typ != NULL && PyType_Check(typ));
if (sym->flags & IS_NULL) {
sym_set_bottom(sym);
return;
return false;
}
if (sym->typ != NULL) {
if (sym->typ != typ) {
sym_set_bottom(sym);
return false;
}
return;
}
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
else {
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
}
return true;
}
void
bool
_Py_uop_sym_set_const(_Py_UopsSymbol *sym, PyObject *const_val)
{
assert(const_val != NULL);
if (sym->flags & IS_NULL) {
sym_set_bottom(sym);
return;
return false;
}
PyTypeObject *typ = Py_TYPE(const_val);
if (sym->typ != NULL && sym->typ != typ) {
sym_set_bottom(sym);
return;
return false;
}
if (sym->const_val != NULL) {
if (sym->const_val != const_val) {
// TODO: What if they're equal?
sym_set_bottom(sym);
return false;
}
return;
}
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
sym->const_val = Py_NewRef(const_val);
else {
sym_set_flag(sym, NOT_NULL);
sym->typ = typ;
sym->const_val = Py_NewRef(const_val);
}
return true;
}
void
bool
_Py_uop_sym_set_null(_Py_UopsSymbol *sym)
{
sym_set_flag(sym, IS_NULL);
return !_Py_uop_sym_is_bottom(sym);
}
void
bool
_Py_uop_sym_set_non_null(_Py_UopsSymbol *sym)
{
sym_set_flag(sym, NOT_NULL);
return !_Py_uop_sym_is_bottom(sym);
}

4
Tools/cases_generator/optimizer_generator.py
View File

@ -4,16 +4,12 @@ Writes the cases to optimizer_cases.c.h, which is #included in Python/optimizer_
"""
import argparse
import os.path
import sys
from analyzer import (
Analysis,
Instruction,
Uop,
Part,
analyze_files,
Skip,
StackItem,
analysis_error,
)