diff options
| -rw-r--r-- | Lib/test/test_peepholer.py | 4 | ||||
| -rw-r--r-- | Python/compile.c | 20 |
2 files changed, 19 insertions, 5 deletions
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py index 4222424..34bd99f 100644 --- a/Lib/test/test_peepholer.py +++ b/Lib/test/test_peepholer.py @@ -129,6 +129,10 @@ class TestTranforms(unittest.TestCase): self.assert_('(2)' in asm) self.assert_("('b')" in asm) + # Verify that large sequences do not result from folding + asm = dis_single('a="x"*1000') + self.assert_('(1000)' in asm) + def test_elim_extra_return(self): # RETURN LOAD_CONST None RETURN --> RETURN def f(x): diff --git a/Python/compile.c b/Python/compile.c index 545042f..acfbfe1 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -444,12 +444,16 @@ tuple_of_constants(unsigned char *codestr, int n, PyObject *consts) The consts table must still be in list form so that the new constant can be appended. Called with codestr pointing to the first LOAD_CONST. - Abandons the transformation if the folding fails (i.e. 1+'a'). */ + Abandons the transformation if the folding fails (i.e. 1+'a'). + If the new constant is a sequence, only folds when the size + is below a threshold value. That keeps pyc files from + becoming large in the presence of code like: (None,)*1000. +*/ static int fold_binops_on_constants(unsigned char *codestr, PyObject *consts) { PyObject *newconst, *v, *w; - int len_consts, opcode; + int len_consts, opcode, size; /* Pre-conditions */ assert(PyList_CheckExact(consts)); @@ -468,8 +472,8 @@ fold_binops_on_constants(unsigned char *codestr, PyObject *consts) newconst = PyNumber_Multiply(v, w); break; case BINARY_DIVIDE: - /* XXX care is needed to fold this operation statically: - the result might depend on the run-time presence of the -Qnew flag */ + /* Cannot fold this operation statically since + the result can depend on the run-time presence of the -Qnew flag */ return 0; case BINARY_TRUE_DIVIDE: newconst = PyNumber_TrueDivide(v, w); @@ -513,6 +517,13 @@ fold_binops_on_constants(unsigned char *codestr, PyObject *consts) PyErr_Clear(); return 0; } + size = PyObject_Size(newconst); + if (size == -1) + PyErr_Clear(); + else if (size > 20) { + Py_DECREF(newconst); + return 0; + } /* Append folded constant into consts table */ len_consts = PyList_GET_SIZE(consts); @@ -733,7 +744,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen LOAD_CONST c1 LOAD_CONST c2 BINOP --> LOAD_CONST binop(c1,c2) */ case BINARY_POWER: case BINARY_MULTIPLY: - case BINARY_DIVIDE: case BINARY_TRUE_DIVIDE: case BINARY_FLOOR_DIVIDE: case BINARY_MODULO: |