Hi all!
I reduced my array aliasing libstdc++ failures to the following
testcase:
struct iterator
{
int* ptr;
iterator(int* _ptr) : ptr(_ptr) {}
};
struct container {
int* first;
container(int* _first) : first(_first) {}
iterator begin() { return iterator(first); }
};
bool includes(const iterator&);
bool test4()
{
int array[] = {2, 4};
container con(array);
return includes(con.begin());
}
the weird thing now is, that the alias1 dump contains
# SFT.2_19 = V_MAY_DEF <SFT.2_2>;
# SFT.4_20 = V_MAY_DEF <SFT.4_15>;
D.1797_16 = includes (&D.1794);
i.e. it misses the V_MAY_DEF for SFT.1 (array, UID 1783, int[2], is
addressable, sub-vars: { SFT.2 SFT.1 }), while the alias2 dump
is ok:
# SFT.1_9 = V_MAY_DEF <SFT.1_3>;
# SFT.2_19 = V_MAY_DEF <SFT.2_2>;
# SFT.4_20 = V_MAY_DEF <SFT.4_15>;
D.1797_16 = includes (&D.1794);
unfortunately, at that time DCE already decided to remove the
array[1] initialization.
The difference seems to be in the Pointed-to sets; alias1 contains
SFT.0_10
SFT.3_6
SFT.4_14
SFT.5_12
_first_5, its value escapes, points-to vars: { SFT.2 }
D.1810_8, points-to vars: { SFT.2 }
_ptr_9, its value escapes, points-to vars: { SFT.2 }
while alias2 is only
SFT.0_10
SFT.3_6
SFT.4_14
SFT.5_12
_ptr_8, points-to vars: { }
So maybe from there we miscompute flow-insensitive alias information
which differs in only
- SFT.1, UID 1815, int, is addressable, default def: SFT.1_3
+ SFT.1, UID 1815, int, is addressable, call clobbered, default def: SFT.1_3
I attached the two alias dumps for reference. Maybe you can point
out what is going wrong - I'm somewhat lost here.
Thanks,
Richard.
;; Function bool test4() (_Z5test4v)
Points-to analysis
Constraints:
ANYTHING = &ANYTHING
READONLY = &ANYTHING
INTEGER = &ANYTHING
ANYOFFSET = &ANYOFFSET
_first_5 = &array
con = _first_5
D.1810_8 = con
_ptr_9 = D.1810_8
D.1809 = _ptr_9
D.1796 = D.1809
D.1794 = D.1796
D.1797_16 = &ANYTHING
Collapsing static cycles and doing variable substitution:
Collapsing con into _first_5
Collapsing D.1810_8 into _first_5
Collapsing _ptr_9 into _first_5
Collapsing D.1809 into _first_5
Collapsing D.1796 into _first_5
Collapsing D.1794 into _first_5
Solving graph:
Points-to sets
NULL = { }
ANYTHING = { ANYTHING }
READONLY = { ANYTHING }
INTEGER = { ANYTHING }
ANYOFFSET = { ANYOFFSET }
_first_5 = { array }
array = { }
array.1 = { }
con = { array }
D.1810_8 = { array }
_ptr_9 = { array }
D.1809 = { array }
D.1796 = { array }
D.1794 = { array }
D.1797_16 = { ANYTHING }
test4: Total number of aliased vops: 0
Referenced variables in test4: 17
Variable: SFT.0, UID 1814, int *, default def: SFT.0_10
Variable: SFT.1, UID 1815, int, is addressable, default def: SFT.1_3
Variable: _first, UID 1808, int *
Variable: D.1809, UID 1809, struct iterator, sub-vars: { SFT.0 }
Variable: D.1810, UID 1810, int *
Variable: _ptr, UID 1811, int *
Variable: <retval>, UID 1782, int
Variable: array, UID 1783, int[2], is addressable, sub-vars: { SFT.2 SFT.1 }
Variable: con, UID 1784, struct container, sub-vars: { SFT.3 }
Variable: SFT.2, UID 1816, int, is addressable, call clobbered, default def:
SFT.2_1
Variable: SFT.3, UID 1817, int *, default def: SFT.3_6
Variable: SFT.4, UID 1818, int *, is addressable, call clobbered, default def:
SFT.4_14
Variable: SFT.5, UID 1819, int *, default def: SFT.5_12
Variable: D.1794, UID 1794, struct iterator, is addressable, sub-vars: { SFT.4 }
Variable: D.1795, UID 1795, int
Variable: D.1796, UID 1796, struct iterator, sub-vars: { SFT.5 }
Variable: D.1797, UID 1797, bool
Pointed-to sets for pointers in bool test4()
SFT.0_10
SFT.3_6
SFT.4_14
SFT.5_12
_first_5, its value escapes, points-to vars: { SFT.2 }
D.1810_8, points-to vars: { SFT.2 }
_ptr_9, its value escapes, points-to vars: { SFT.2 }
Flow-insensitive alias information for bool test4()
Aliased symbols
SFT.1, UID 1815, int, is addressable, default def: SFT.1_3
array, UID 1783, int[2], is addressable, sub-vars: { SFT.2 SFT.1 }
SFT.2, UID 1816, int, is addressable, call clobbered, default def: SFT.2_1
SFT.4, UID 1818, int *, is addressable, call clobbered, default def: SFT.4_14
D.1794, UID 1794, struct iterator, is addressable, sub-vars: { SFT.4 }
Dereferenced pointers
Type memory tags
Flow-sensitive alias information for bool test4()
SSA_NAME pointers
Name memory tags
Registering new PHI nodes in block #-1
Registering new PHI nodes in block #0
Updating SSA information for statement array[0] = 2;
Updating SSA information for statement array[1] = 4;
Updating SSA information for statement con.first = _first_5;
Updating SSA information for statement D.1810_8 = con.first;
Updating SSA information for statement D.1809.ptr = _ptr_9;
Updating SSA information for statement D.1796 = D.1809;
Updating SSA information for statement D.1794 = D.1796;
Updating SSA information for statement D.1797_16 = includes (&D.1794);
Symbols to be put in SSA form
array con D.1794 D.1809 SFT.0 SFT.1 SFT.2 SFT.3 SFT.4
Incremental SSA update started at block: -1
Number of blocks in CFG: 1
Number of blocks to update: 1 (100%)
Affected blocks: 0
bool test4() ()
{
int * _ptr;
struct iterator D.1809;
int * D.1810;
struct iterator D.1809;
int * _first;
struct container con;
int array[2];
bool D.1797;
struct iterator D.1796;
struct iterator D.1794;
int D.1795;
<bb 0>:
# SFT.2_2 = V_MUST_DEF <SFT.2_1>;
array[0] = 2;
# SFT.1_4 = V_MUST_DEF <SFT.1_3>;
array[1] = 4;
_first_5 = &array[0];
# SFT.3_7 = V_MUST_DEF <SFT.3_6>;
con.first = _first_5;
# VUSE <SFT.3_7>;
D.1810_8 = con.first;
_ptr_9 = D.1810_8;
# SFT.0_11 = V_MUST_DEF <SFT.0_10>;
D.1809.ptr = _ptr_9;
# SFT.5_13 = V_MUST_DEF <SFT.5_12>;
# VUSE <SFT.0_11>;
D.1796 = D.1809;
# SFT.4_15 = V_MUST_DEF <SFT.4_14>;
# VUSE <SFT.5_13>;
D.1794 = D.1796;
# SFT.2_19 = V_MAY_DEF <SFT.2_2>;
# SFT.4_20 = V_MAY_DEF <SFT.4_15>;
D.1797_16 = includes (&D.1794);
D.1795_17 = (int) D.1797_16;
return D.1795_17;
}
;; Function bool test4() (_Z5test4v)
Points-to analysis
Constraints:
ANYTHING = &ANYTHING
READONLY = &ANYTHING
INTEGER = &ANYTHING
ANYOFFSET = &ANYOFFSET
con = &array
_ptr_8 = &array
D.1809 = &array
D.1796 = D.1809
D.1794 = D.1796
D.1797_16 = &ANYTHING
Collapsing static cycles and doing variable substitution:
Collapsing D.1796 into D.1809
Collapsing D.1794 into D.1809
Solving graph:
Points-to sets
NULL = { }
ANYTHING = { ANYTHING }
READONLY = { ANYTHING }
INTEGER = { ANYTHING }
ANYOFFSET = { ANYOFFSET }
con = { array }
array = { }
array.1 = { }
_ptr_8 = { array }
D.1809 = { array }
D.1796 = { array }
D.1794 = { array }
D.1797_16 = { ANYTHING }
test4: Total number of aliased vops: 0
Referenced variables in test4: 17
Variable: SFT.0, UID 1814, int *, default def: SFT.0_10
Variable: SFT.1, UID 1815, int, is addressable, call clobbered, default def:
SFT.1_3
Variable: _first, UID 1808, int *
Variable: D.1809, UID 1809, struct iterator, sub-vars: { SFT.0 }
Variable: D.1810, UID 1810, int *
Variable: _ptr, UID 1811, int *
Variable: <retval>, UID 1782, int
Variable: array, UID 1783, int[2], is addressable, sub-vars: { SFT.2 SFT.1 }
Variable: con, UID 1784, struct container, sub-vars: { SFT.3 }
Variable: SFT.2, UID 1816, int, is addressable, call clobbered, default def:
SFT.2_1
Variable: SFT.3, UID 1817, int *, default def: SFT.3_6
Variable: SFT.4, UID 1818, int *, is addressable, call clobbered, default def:
SFT.4_14
Variable: SFT.5, UID 1819, int *, default def: SFT.5_12
Variable: D.1794, UID 1794, struct iterator, is addressable, sub-vars: { SFT.4 }
Variable: D.1795, UID 1795, int
Variable: D.1796, UID 1796, struct iterator, sub-vars: { SFT.5 }
Variable: D.1797, UID 1797, bool
Pointed-to sets for pointers in bool test4()
SFT.0_10
SFT.3_6
SFT.4_14
SFT.5_12
_ptr_8, points-to vars: { }
Flow-insensitive alias information for bool test4()
Aliased symbols
SFT.1, UID 1815, int, is addressable, call clobbered, default def: SFT.1_3
array, UID 1783, int[2], is addressable, sub-vars: { SFT.2 SFT.1 }
SFT.2, UID 1816, int, is addressable, call clobbered, default def: SFT.2_1
SFT.4, UID 1818, int *, is addressable, call clobbered, default def: SFT.4_14
D.1794, UID 1794, struct iterator, is addressable, sub-vars: { SFT.4 }
Dereferenced pointers
Type memory tags
Flow-sensitive alias information for bool test4()
SSA_NAME pointers
Name memory tags
Registering new PHI nodes in block #-1
Registering new PHI nodes in block #0
Updating SSA information for statement array[0] = 2;
Updating SSA information for statement D.1794 = D.1796;
Updating SSA information for statement D.1797_16 = includes (&D.1794);
Symbols to be put in SSA form
array D.1794 SFT.1 SFT.2 SFT.4
Incremental SSA update started at block: -1
Number of blocks in CFG: 1
Number of blocks to update: 1 (100%)
Affected blocks: 0
bool test4() ()
{
int * _ptr;
struct iterator D.1809;
int * D.1810;
struct iterator D.1809;
int * _first;
struct container con;
int array[2];
bool D.1797;
struct iterator D.1796;
struct iterator D.1794;
int D.1795;
<bb 0>:
# SFT.2_2 = V_MUST_DEF <SFT.2_1>;
array[0] = 2;
# SFT.3_7 = V_MUST_DEF <SFT.3_6>;
con.first = &array[0];
_ptr_8 = &array[0];
# SFT.0_11 = V_MUST_DEF <SFT.0_10>;
D.1809.ptr = &array[0];
# SFT.5_13 = V_MUST_DEF <SFT.5_12>;
# VUSE <SFT.0_11>;
D.1796 = D.1809;
# SFT.4_15 = V_MUST_DEF <SFT.4_14>;
# VUSE <SFT.5_13>;
D.1794 = D.1796;
# SFT.1_9 = V_MAY_DEF <SFT.1_3>;
# SFT.2_19 = V_MAY_DEF <SFT.2_2>;
# SFT.4_20 = V_MAY_DEF <SFT.4_15>;
D.1797_16 = includes (&D.1794);
D.1795_17 = (int) D.1797_16;
return D.1795_17;
}
