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[mypyc] Don't free target of LoadMem too early (python#9299)
Add optional reference to the object from which we are reading from to `LoadMem` so that the object won't be freed before we read memory. Fixes mypyc/mypyc#756.
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9 files changed

+62
-27
lines changed

9 files changed

+62
-27
lines changed

‎mypyc/ir/ops.py

Lines changed: 23 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1348,25 +1348,42 @@ def accept(self, visitor: 'OpVisitor[T]') -> T:
13481348

13491349

13501350
class LoadMem(RegisterOp):
1351-
"""Reading a memory location
1352-
1353-
type ret = *(type*)src
1351+
"""Read a memory location.
1352+
1353+
type ret = *(type *)src
1354+
1355+
Attributes:
1356+
type: Type of the read value
1357+
src: Pointer to memory to read
1358+
base: If not None, the object from which we are reading memory.
1359+
It's used to avoid the target object from being freed via
1360+
reference counting. If the target is not in reference counted
1361+
memory, or we know that the target won't be freed, it can be
1362+
None.
13541363
"""
13551364
error_kind = ERR_NEVER
13561365

1357-
def __init__(self, type: RType, src: Value, line: int = -1) -> None:
1366+
def __init__(self, type: RType, src: Value, base: Optional[Value], line: int = -1) -> None:
13581367
super().__init__(line)
13591368
self.type = type
13601369
# TODO: for now we enforce that the src memory address should be Py_ssize_t
13611370
# later we should also support same width unsigned int
13621371
assert is_pointer_rprimitive(src.type)
13631372
self.src = src
1373+
self.base = base
13641374

13651375
def sources(self) -> List[Value]:
1366-
return [self.src]
1376+
if self.base:
1377+
return [self.src, self.base]
1378+
else:
1379+
return [self.src]
13671380

13681381
def to_str(self, env: Environment) -> str:
1369-
return env.format("%r = load_mem %r :: %r*", self, self.src, self.type)
1382+
if self.base:
1383+
base = env.format(', %r', self.base)
1384+
else:
1385+
base = ''
1386+
return env.format("%r = load_mem %r%s :: %r*", self, self.src, base, self.type)
13701387

13711388
def accept(self, visitor: 'OpVisitor[T]') -> T:
13721389
return visitor.visit_load_mem(self)

‎mypyc/irbuild/ll_builder.py

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -826,7 +826,7 @@ def builtin_len(self, val: Value, line: int) -> Value:
826826
typ = val.type
827827
if is_list_rprimitive(typ) or is_tuple_rprimitive(typ):
828828
elem_address = self.add(GetElementPtr(val, PyVarObject, 'ob_size'))
829-
size_value = self.add(LoadMem(c_pyssize_t_rprimitive, elem_address))
829+
size_value = self.add(LoadMem(c_pyssize_t_rprimitive, elem_address, val))
830830
offset = self.add(LoadInt(1, line, rtype=c_pyssize_t_rprimitive))
831831
return self.binary_int_op(short_int_rprimitive, size_value, offset,
832832
BinaryIntOp.LEFT_SHIFT, line)
@@ -837,7 +837,7 @@ def builtin_len(self, val: Value, line: int) -> Value:
837837
BinaryIntOp.LEFT_SHIFT, line)
838838
elif is_set_rprimitive(typ):
839839
elem_address = self.add(GetElementPtr(val, PySetObject, 'used'))
840-
size_value = self.add(LoadMem(c_pyssize_t_rprimitive, elem_address))
840+
size_value = self.add(LoadMem(c_pyssize_t_rprimitive, elem_address, val))
841841
offset = self.add(LoadInt(1, line, rtype=c_pyssize_t_rprimitive))
842842
return self.binary_int_op(short_int_rprimitive, size_value, offset,
843843
BinaryIntOp.LEFT_SHIFT, line)

‎mypyc/test-data/irbuild-basic.test

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1368,7 +1368,7 @@ def lst(x):
13681368
r3 :: bool
13691369
L0:
13701370
r0 = get_element_ptr x ob_size :: PyVarObject
1371-
r1 = load_mem r0 :: native_int*
1371+
r1 = load_mem r0, x :: native_int*
13721372
r2 = r1 << 1
13731373
r3 = r2 != 0
13741374
if r3 goto L1 else goto L2 :: bool
@@ -1980,7 +1980,7 @@ L0:
19801980
r5 = 0
19811981
L1:
19821982
r6 = get_element_ptr r4 ob_size :: PyVarObject
1983-
r7 = load_mem r6 :: native_int*
1983+
r7 = load_mem r6, r4 :: native_int*
19841984
r8 = r7 << 1
19851985
r9 = r5 < r8 :: signed
19861986
if r9 goto L2 else goto L14 :: bool
@@ -2065,7 +2065,7 @@ L0:
20652065
r5 = 0
20662066
L1:
20672067
r6 = get_element_ptr r4 ob_size :: PyVarObject
2068-
r7 = load_mem r6 :: native_int*
2068+
r7 = load_mem r6, r4 :: native_int*
20692069
r8 = r7 << 1
20702070
r9 = r5 < r8 :: signed
20712071
if r9 goto L2 else goto L14 :: bool
@@ -2152,7 +2152,7 @@ L0:
21522152
r0 = 0
21532153
L1:
21542154
r1 = get_element_ptr l ob_size :: PyVarObject
2155-
r2 = load_mem r1 :: native_int*
2155+
r2 = load_mem r1, l :: native_int*
21562156
r3 = r2 << 1
21572157
r4 = r0 < r3 :: signed
21582158
if r4 goto L2 else goto L4 :: bool
@@ -2174,7 +2174,7 @@ L4:
21742174
r12 = 0
21752175
L5:
21762176
r13 = get_element_ptr l ob_size :: PyVarObject
2177-
r14 = load_mem r13 :: native_int*
2177+
r14 = load_mem r13, l :: native_int*
21782178
r15 = r14 << 1
21792179
r16 = r12 < r15 :: signed
21802180
if r16 goto L6 else goto L8 :: bool

‎mypyc/test-data/irbuild-lists.test

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -117,7 +117,7 @@ def f(a):
117117
r2 :: short_int
118118
L0:
119119
r0 = get_element_ptr a ob_size :: PyVarObject
120-
r1 = load_mem r0 :: native_int*
120+
r1 = load_mem r0, a :: native_int*
121121
r2 = r1 << 1
122122
return r2
123123

@@ -156,7 +156,7 @@ def increment(l):
156156
r9 :: short_int
157157
L0:
158158
r0 = get_element_ptr l ob_size :: PyVarObject
159-
r1 = load_mem r0 :: native_int*
159+
r1 = load_mem r0, l :: native_int*
160160
r2 = r1 << 1
161161
r3 = 0
162162
i = r3
@@ -196,4 +196,3 @@ L0:
196196
r5 = box(short_int, 6)
197197
r6 = PyList_Append(r2, r5)
198198
return r2
199-

‎mypyc/test-data/irbuild-set.test

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -69,7 +69,7 @@ L0:
6969
r5 = box(short_int, 6)
7070
r6 = PySet_Add(r0, r5)
7171
r7 = get_element_ptr r0 used :: PySetObject
72-
r8 = load_mem r7 :: native_int*
72+
r8 = load_mem r7, r0 :: native_int*
7373
r9 = r8 << 1
7474
return r9
7575

@@ -223,4 +223,3 @@ L0:
223223
r7 = box(short_int, 6)
224224
r8 = PySet_Add(r0, r7)
225225
return r0
226-

‎mypyc/test-data/irbuild-statements.test

Lines changed: 4 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -323,7 +323,7 @@ L0:
323323
r0 = 0
324324
L1:
325325
r1 = get_element_ptr ls ob_size :: PyVarObject
326-
r2 = load_mem r1 :: native_int*
326+
r2 = load_mem r1, ls :: native_int*
327327
r3 = r2 << 1
328328
r4 = r0 < r3 :: signed
329329
if r4 goto L2 else goto L4 :: bool
@@ -848,7 +848,7 @@ L0:
848848
r1 = 0
849849
L1:
850850
r2 = get_element_ptr a ob_size :: PyVarObject
851-
r3 = load_mem r2 :: native_int*
851+
r3 = load_mem r2, a :: native_int*
852852
r4 = r3 << 1
853853
r5 = r1 < r4 :: signed
854854
if r5 goto L2 else goto L4 :: bool
@@ -926,7 +926,7 @@ L0:
926926
r1 = PyObject_GetIter(b)
927927
L1:
928928
r2 = get_element_ptr a ob_size :: PyVarObject
929-
r3 = load_mem r2 :: native_int*
929+
r3 = load_mem r2, a :: native_int*
930930
r4 = r3 << 1
931931
r5 = r0 < r4 :: signed
932932
if r5 goto L2 else goto L7 :: bool
@@ -977,7 +977,7 @@ L1:
977977
if is_error(r3) goto L6 else goto L2
978978
L2:
979979
r4 = get_element_ptr b ob_size :: PyVarObject
980-
r5 = load_mem r4 :: native_int*
980+
r5 = load_mem r4, b :: native_int*
981981
r6 = r5 << 1
982982
r7 = r1 < r6 :: signed
983983
if r7 goto L3 else goto L6 :: bool
@@ -1002,4 +1002,3 @@ L6:
10021002
r14 = CPy_NoErrOccured()
10031003
L7:
10041004
return 1
1005-

‎mypyc/test-data/irbuild-tuple.test

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -67,7 +67,7 @@ def f(x):
6767
r2 :: short_int
6868
L0:
6969
r0 = get_element_ptr x ob_size :: PyVarObject
70-
r1 = load_mem r0 :: native_int*
70+
r1 = load_mem r0, x :: native_int*
7171
r2 = r1 << 1
7272
return r2
7373

@@ -134,7 +134,7 @@ L0:
134134
r0 = 0
135135
L1:
136136
r1 = get_element_ptr xs ob_size :: PyVarObject
137-
r2 = load_mem r1 :: native_int*
137+
r2 = load_mem r1, xs :: native_int*
138138
r3 = r2 << 1
139139
r4 = r0 < r3 :: signed
140140
if r4 goto L2 else goto L4 :: bool
@@ -176,4 +176,3 @@ L2:
176176
r2 = CPySequenceTuple_GetItem(nt, 2)
177177
r3 = unbox(int, r2)
178178
return r3
179-

‎mypyc/test-data/refcount.test

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -831,3 +831,23 @@ L2:
831831
L3:
832832
return 1
833833

834+
[case testGetElementPtrLifeTime]
835+
from typing import List
836+
837+
def f() -> int:
838+
x: List[str] = []
839+
return len(x)
840+
[out]
841+
def f():
842+
r0, x :: list
843+
r1 :: ptr
844+
r2 :: native_int
845+
r3 :: short_int
846+
L0:
847+
r0 = []
848+
x = r0
849+
r1 = get_element_ptr x ob_size :: PyVarObject
850+
r2 = load_mem r1, x :: native_int*
851+
dec_ref x
852+
r3 = r2 << 1
853+
return r3

‎mypyc/test/test_emitfunc.py

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -262,8 +262,10 @@ def test_binary_int_op(self) -> None:
262262
"""cpy_r_r04 = (uint64_t)cpy_r_i64 < (uint64_t)cpy_r_i64_1;""")
263263

264264
def test_load_mem(self) -> None:
265-
self.assert_emit(LoadMem(bool_rprimitive, self.ptr),
265+
self.assert_emit(LoadMem(bool_rprimitive, self.ptr, None),
266266
"""cpy_r_r0 = *(char *)cpy_r_ptr;""")
267+
self.assert_emit(LoadMem(bool_rprimitive, self.ptr, self.s1),
268+
"""cpy_r_r00 = *(char *)cpy_r_ptr;""")
267269

268270
def test_get_element_ptr(self) -> None:
269271
r = RStruct("Foo", ["b", "i32", "i64"], [bool_rprimitive,

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