Re: Segmentation fault in Braun Tree example (modified)
Okay, that was embarrassing! I should probably have rested a bit before
having another look at it before posting it. Thank you for the fix. :-)
> When I encounter a segfault, it is usually caused by recursion depth
being over some kind of limit.
Thank you! This is a useful tip to keep in mind.
Cheers,
Timmy
On Thursday, August 20, 2020 at 9:39:22 PM UTC+5:30 gmhwxi wrote:
> When I encounter a segfault, it is usually caused by recursion depth being
> over some kind of limit.
>
> In your code, the 'aux' function is defined but never called. Here is a
> fixed version:
>
> fun
> {a: t@ype}
> brauntest1 (t0: tree a): bool =
> let exception Negative of ()
> fun aux (t0: tree a): bool =
> case+ t0 of
> | tree_nil () => true
> | tree_cons (tl, _, tr) =>
> let val szl = size (tl)
> val szr = size (tr)
> in
> if abs (szl - szr) > 1 then $raise Negative ()
> else aux(tl) andalso aux(tr)
> end
> in
> try aux(t0) with ~Negative () => false
> end
>
> On Thu, Aug 20, 2020 at 6:46 AM Timmy Jose wrote:
>
>>
>>
>> Hi,
>>
>> I have a variation of the Braun Tree test (where the size of the left and
>> right subtrees differ by at most 1 at every level) from the tutorials, and
>> this one, for some reason gives a segmentation fault.
>>
>> Here is the snippet:
>>
>> fun
>> {a: t@ype}
>> brauntest1 (t0: tree a): bool =
>> let exception Negative of ()
>> fun aux (t0: tree a): bool =
>> case+ t0 of
>> | tree_nil () => true
>> | tree_cons (tl, _, tr) =>
>> let val szl = size (tl)
>> val szr = size (tr)
>> in
>> if abs (szl - szr) > 1 then $raise Negative ()
>> else brauntest1 (tl) andalso brauntest1 (tr)
>> end
>> in
>> try brauntest1 (t0) with ~Negative () => false
>> end
>>
>> And here is the output from `lldb` (gdb has some code-signing issues on
>> macOS).
>>
>> $ lldb braun
>> (lldb) target create "braun"
>> Current executable set to 'braun' (x86_64).
>> (lldb) r
>> Process 28137 launched: '/braun' (x86_64)
>> Process 28137 stopped
>> * thread #1, queue = 'com.apple.main-thread', stop reason =
>> EXC_BAD_ACCESS (code=2, address=0x7ffeef3fff68)
>> frame #0: 0x00011577 braun`brauntest1_3__3__1 + 39
>> braun`brauntest1_3__3__1:
>> -> 0x11577 <+39>: callq 0x11c3a ; symbol stub
>> for: setjmp
>> 0x1157c <+44>: testl %eax, %eax
>> 0x1157e <+46>: je 0x115de ; <+142>
>> 0x11580 <+48>: movq 0xb31(%rip), %rcx ;
>> my_atsexnframe_getref.my_atsexnframe
>> Target 0: (braun) stopped.
>> (lldb)
>>
>> Anybody seen this before, or have an idea what might be going wrong?
>>
>> Thanks!
>>
>> Timmy
>>
>> --
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>> "ats-lang-users" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to ats-lang-user...@googlegroups.com.
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>>
>>
>> .
>>
>
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Re: Segmentation fault in Braun Tree example (modified)
When I encounter a segfault, it is usually caused by recursion depth being
over some kind of limit.
In your code, the 'aux' function is defined but never called. Here is a
fixed version:
fun
{a: t@ype}
brauntest1 (t0: tree a): bool =
let exception Negative of ()
fun aux (t0: tree a): bool =
case+ t0 of
| tree_nil () => true
| tree_cons (tl, _, tr) =>
let val szl = size (tl)
val szr = size (tr)
in
if abs (szl - szr) > 1 then $raise Negative ()
else aux(tl) andalso aux(tr)
end
in
try aux(t0) with ~Negative () => false
end
On Thu, Aug 20, 2020 at 6:46 AM Timmy Jose wrote:
>
>
> Hi,
>
> I have a variation of the Braun Tree test (where the size of the left and
> right subtrees differ by at most 1 at every level) from the tutorials, and
> this one, for some reason gives a segmentation fault.
>
> Here is the snippet:
>
> fun
> {a: t@ype}
> brauntest1 (t0: tree a): bool =
> let exception Negative of ()
> fun aux (t0: tree a): bool =
> case+ t0 of
> | tree_nil () => true
> | tree_cons (tl, _, tr) =>
> let val szl = size (tl)
> val szr = size (tr)
> in
> if abs (szl - szr) > 1 then $raise Negative ()
> else brauntest1 (tl) andalso brauntest1 (tr)
> end
> in
> try brauntest1 (t0) with ~Negative () => false
> end
>
> And here is the output from `lldb` (gdb has some code-signing issues on
> macOS).
>
> $ lldb braun
> (lldb) target create "braun"
> Current executable set to 'braun' (x86_64).
> (lldb) r
> Process 28137 launched: '/braun' (x86_64)
> Process 28137 stopped
> * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS
> (code=2, address=0x7ffeef3fff68)
> frame #0: 0x00011577 braun`brauntest1_3__3__1 + 39
> braun`brauntest1_3__3__1:
> -> 0x11577 <+39>: callq 0x11c3a ; symbol stub for:
> setjmp
> 0x1157c <+44>: testl %eax, %eax
> 0x1157e <+46>: je 0x115de ; <+142>
> 0x11580 <+48>: movq 0xb31(%rip), %rcx ;
> my_atsexnframe_getref.my_atsexnframe
> Target 0: (braun) stopped.
> (lldb)
>
> Anybody seen this before, or have an idea what might be going wrong?
>
> Thanks!
>
> Timmy
>
> --
> You received this message because you are subscribed to the Google Groups
> "ats-lang-users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to ats-lang-users+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
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>
> .
>
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Segmentation fault in Braun Tree example (modified)
Hi,
I have a variation of the Braun Tree test (where the size of the left and
right subtrees differ by at most 1 at every level) from the tutorials, and
this one, for some reason gives a segmentation fault.
Here is the snippet:
fun
{a: t@ype}
brauntest1 (t0: tree a): bool =
let exception Negative of ()
fun aux (t0: tree a): bool =
case+ t0 of
| tree_nil () => true
| tree_cons (tl, _, tr) =>
let val szl = size (tl)
val szr = size (tr)
in
if abs (szl - szr) > 1 then $raise Negative ()
else brauntest1 (tl) andalso brauntest1 (tr)
end
in
try brauntest1 (t0) with ~Negative () => false
end
And here is the output from `lldb` (gdb has some code-signing issues on
macOS).
$ lldb braun
(lldb) target create "braun"
Current executable set to 'braun' (x86_64).
(lldb) r
Process 28137 launched: '/braun' (x86_64)
Process 28137 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS
(code=2, address=0x7ffeef3fff68)
frame #0: 0x00011577 braun`brauntest1_3__3__1 + 39
braun`brauntest1_3__3__1:
-> 0x11577 <+39>: callq 0x11c3a ; symbol stub for:
setjmp
0x1157c <+44>: testl %eax, %eax
0x1157e <+46>: je 0x115de ; <+142>
0x11580 <+48>: movq 0xb31(%rip), %rcx ;
my_atsexnframe_getref.my_atsexnframe
Target 0: (braun) stopped.
(lldb)
Anybody seen this before, or have an idea what might be going wrong?
Thanks!
Timmy
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