From 9cdd2fa63b7549d00830bccf19a34e9d69d0b15e Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Fri, 16 Dec 2022 20:45:55 -0800 Subject: [PATCH] GH-98831: Add DECREF_INPUTS(), expanding to DECREF() each stack input (#100205) The presence of this macro indicates that a particular instruction may be considered for conversion to a register-based format (see https://github.com/faster-cpython/ideas/issues/485). An invariant (currently unchecked) is that `DEOPT_IF()` may only occur *before* `DECREF_INPUTS()`, and `ERROR_IF()` may only occur *after* it. One reason not to check this is that there are a few places where we insert *two* `DECREF_INPUTS()` calls, in different branches of the code. The invariant checking would have to be able to do some flow control analysis to understand this. Note that many instructions, especially specialized ones, can't be converted to use this macro straightforwardly. This is because the generator currently only generates plain `Py_DECREF(variable)` statements, and cannot generate things like `_Py_DECREF_SPECIALIZED()` let alone deal with `_PyList_AppendTakeRef()`. --- Python/bytecodes.c | 31 +++++++++++-------------- Tools/cases_generator/generate_cases.py | 6 ++++- 2 files changed, 18 insertions(+), 19 deletions(-) diff --git a/Python/bytecodes.c b/Python/bytecodes.c index 8e95b737030252..b29e16e080e961 100644 --- a/Python/bytecodes.c +++ b/Python/bytecodes.c @@ -161,7 +161,7 @@ dummy_func( super(LOAD_CONST__LOAD_FAST) = LOAD_CONST + LOAD_FAST; inst(POP_TOP, (value --)) { - Py_DECREF(value); + DECREF_INPUTS(); } inst(PUSH_NULL, (-- res)) { @@ -172,19 +172,19 @@ dummy_func( inst(UNARY_POSITIVE, (value -- res)) { res = PyNumber_Positive(value); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(res == NULL, error); } inst(UNARY_NEGATIVE, (value -- res)) { res = PyNumber_Negative(value); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(res == NULL, error); } inst(UNARY_NOT, (value -- res)) { int err = PyObject_IsTrue(value); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(err < 0, error); if (err == 0) { res = Py_True; @@ -197,7 +197,7 @@ dummy_func( inst(UNARY_INVERT, (value -- res)) { res = PyNumber_Invert(value); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(res == NULL, error); } @@ -351,8 +351,7 @@ dummy_func( STAT_INC(BINARY_SUBSCR, deferred); DECREMENT_ADAPTIVE_COUNTER(cache->counter); res = PyObject_GetItem(container, sub); - Py_DECREF(container); - Py_DECREF(sub); + DECREF_INPUTS(); ERROR_IF(res == NULL, error); } @@ -438,8 +437,7 @@ dummy_func( ERROR_IF(true, error); } Py_INCREF(res); // Do this before DECREF'ing dict, sub - Py_DECREF(dict); - Py_DECREF(sub); + DECREF_INPUTS(); } inst(BINARY_SUBSCR_GETITEM, (unused/1, type_version/2, func_version/1, container, sub -- unused)) { @@ -500,9 +498,7 @@ dummy_func( DECREMENT_ADAPTIVE_COUNTER(cache->counter); /* container[sub] = v */ int err = PyObject_SetItem(container, sub, v); - Py_DECREF(v); - Py_DECREF(container); - Py_DECREF(sub); + DECREF_INPUTS(); ERROR_IF(err, error); } @@ -538,8 +534,7 @@ dummy_func( inst(DELETE_SUBSCR, (container, sub --)) { /* del container[sub] */ int err = PyObject_DelItem(container, sub); - Py_DECREF(container); - Py_DECREF(sub); + DECREF_INPUTS(); ERROR_IF(err, error); } @@ -550,11 +545,11 @@ dummy_func( if (hook == NULL) { _PyErr_SetString(tstate, PyExc_RuntimeError, "lost sys.displayhook"); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(true, error); } res = PyObject_CallOneArg(hook, value); - Py_DECREF(value); + DECREF_INPUTS(); ERROR_IF(res == NULL, error); Py_DECREF(res); } @@ -625,12 +620,12 @@ dummy_func( "'async for' requires an object with " "__aiter__ method, got %.100s", type->tp_name); - Py_DECREF(obj); + DECREF_INPUTS(); ERROR_IF(true, error); } iter = (*getter)(obj); - Py_DECREF(obj); + DECREF_INPUTS(); ERROR_IF(iter == NULL, error); if (Py_TYPE(iter)->tp_as_async == NULL || diff --git a/Tools/cases_generator/generate_cases.py b/Tools/cases_generator/generate_cases.py index 2dfc76f2560eae..85a7c6098e0b95 100644 --- a/Tools/cases_generator/generate_cases.py +++ b/Tools/cases_generator/generate_cases.py @@ -209,7 +209,7 @@ def write_body(self, out: Formatter, dedent: int, cache_adjust: int = 0) -> None cache_offset += ceffect.size assert cache_offset == self.cache_offset + cache_adjust - # Write the body, substituting a goto for ERROR_IF() + # Write the body, substituting a goto for ERROR_IF() and other stuff assert dedent <= 0 extra = " " * -dedent for line in self.block_text: @@ -232,6 +232,10 @@ def write_body(self, out: Formatter, dedent: int, cache_adjust: int = 0) -> None ) else: out.write_raw(f"{extra}{space}if ({cond}) goto {label};\n") + elif m := re.match(r"(\s*)DECREF_INPUTS\(\);\s*$", line): + space = m.group(1) + for ieff in self.input_effects: + out.write_raw(f"{extra}{space}Py_DECREF({ieff.name});\n") else: out.write_raw(extra + line)