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Levo DeLellis via llvm-dev

2020-Feb-15 16:17 UTC

[llvm-dev] Have the debugger show an away with a dynamic size?

Thanks for the suggestions but it doesn't appear to be working correctly
for me. I tried building the below after seeing the results with "clang -g
-std=c99 test.c" and got the same result

LLDB thinks MyArray is 81 elements long even though 81 and 80 doesn't show
up anywhere in the llvm-ir (I tried again using an llvm ir file made by
clang -g -std=c99 test.c -S -emit-llvm and clang -g test.ll)

$ cat test.c
int foo(int s) {
    int MyArray[s];
    int i;
    for (i = 0; i < s; ++i)
        MyArray[i] = s;
    return 0;
}

int main(){
    foo(5);
    return 0;
}
$ clang -g test.c
$ lldb ./a.out
(lldb) target create "./a.out"
Current executable set to './a.out' (x86_64).
(lldb) break set -f test.c -l 6
Breakpoint 1: where = a.out`foo + 101 at test.c:7, address 0x0000000000400505
(lldb) r
Process 3205 launched: './a.out' (x86_64)
Process 3205 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000000000400505 a.out`foo(s=5) at test.c:7
   4      for (i = 0; i < s; ++i)
   5          MyArray[i] = s;
   6      return 0;
-> 7   }
   8
   9   int main(){
   10      foo(5);
(lldb) frame variable
(int) s = 5
(unsigned long) __vla_expr0 = 5
(int) i = 5
(int [81]) MyArray = {
  [0] = 5
  [1] = 5
  [2] = 5
  [3] = 5
  [4] = 5
  [5] = 0
  [6] = -136481184
  [7] = 32767
  [8] = -8408
  [9] = 32767
  [10] = -8544
  [11] = 32767
  [12] = 1
  [13] = 5
  [14] = 5
  [15] = 0
  [16] = -8512
  [17] = 32767
  [18] = 0
  [19] = 5
  [20] = -8432
  [21] = 32767
  [22] = 4195641
  [23] = 0
  [24] = -8208
  [25] = 32767
  [26] = 0
  [27] = 0
  [28] = 4195664
  [29] = 0
  [30] = -140485737
  [31] = 32767
  [32] = 0
  [33] = 32
  [34] = -8200
  [35] = 32767
  [36] = 0
  [37] = 1
  [38] = 4195616
  [39] = 0
  [40] = 0
  [41] = 0
  [42] = -1953144313
  [43] = 1284291557
  [44] = 4195248
  [45] = 0
  [46] = -8208
  [47] = 32767
  [48] = 0
  [49] = 0
  [50] = 0
  [51] = 0
  [52] = 1064657415
  [53] = -1284291430
  [54] = 933978631
  [55] = -1284287451
  [56] = 0
  [57] = 32767
  [58] = 0
  [59] = 0
  [60] = 0
  [61] = 0
  [62] = -136423629
  [63] = 32767
  [64] = -136530376
  [65] = 32767
  [66] = 386784
  [67] = 0
  [68] = 0
  [69] = 0
  [70] = 0
  [71] = 0
  [72] = 0
  [73] = 0
  [74] = 4195248
  [75] = 0
  [76] = -8208
  [77] = 32767
  [78] = 4195290
  [79] = 0
  [80] = -8216
}


On Thu, Feb 13, 2020 at 3:53 PM Adrian Prantl <aprantl at apple.com>
wrote:
> Take a look at the IR clang produces for C99 variable-length arrays.
>
> -- adrian
>
> On Feb 13, 2020, at 10:03 AM, Levo DeLellis via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Hi. I searched and the closest thing I could find was this
> http://lists.llvm.org/pipermail/llvm-dev/2018-February/121348.html
>
> Currently a known sized array looks and debugs as expected. I use
> llvm.dbg.declare with DICompositeType tag: DW_TAG_array_type and the size
> field. In my language arrays are always passed around with a pointer and
> size pair. I'd like debugging to show up as nicely instead of a pointer
> addr with no information about the elements. How would I do this? I
don't
> use the C API, I output llvm-ir directly. I was hoping I can call
> llvm.dbg.declare/addr/value to specify the pointer, name and size of the
> variable but I really have no idea how to pass the size to the debugger.
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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Adrian Prantl via llvm-dev

2020-Feb-17 16:18 UTC

head link

[llvm-dev] Have the debugger show an away with a dynamic size?

That is interesting. According to LLDB's test/lang/c/vla/* frame variable
for a VLA is supposed to work. Frame variable is also supposed to hide the
__vla_expr0 artificial helper variable. Is this an older LLDB from your system
or an LLDB you built from source? If yes, would you mind filing a bugreport
about this?

thanks,
adrian
> On Feb 15, 2020, at 8:17 AM, Levo DeLellis <levo.delellis at
gmail.com> wrote:
> 
> Thanks for the suggestions but it doesn't appear to be working
correctly for me. I tried building the below after seeing the results with
"clang -g -std=c99 test.c" and got the same result
> 
> LLDB thinks MyArray is 81 elements long even though 81 and 80 doesn't
show up anywhere in the llvm-ir (I tried again using an llvm ir file made by
clang -g -std=c99 test.c -S -emit-llvm and clang -g test.ll)
> 
> $ cat test.c
> int foo(int s) {
>     int MyArray[s];
>     int i;
>     for (i = 0; i < s; ++i)
>         MyArray[i] = s;
>     return 0;
> }
> 
> int main(){
>     foo(5);
>     return 0;
> }
> $ clang -g test.c 
> $ lldb ./a.out 
> (lldb) target create "./a.out"
> Current executable set to './a.out' (x86_64).
> (lldb) break set -f test.c -l 6
> Breakpoint 1: where = a.out`foo + 101 at test.c:7, address =
0x0000000000400505
> (lldb) r
> Process 3205 launched: './a.out' (x86_64)
> Process 3205 stopped
> * thread #1, name = 'a.out', stop reason = breakpoint 1.1
>     frame #0: 0x0000000000400505 a.out`foo(s=5) at test.c:7
>    4      for (i = 0; i < s; ++i)
>    5          MyArray[i] = s;
>    6      return 0;
> -> 7   }
>    8   
>    9   int main(){
>    10      foo(5);
> (lldb) frame variable
> (int) s = 5
> (unsigned long) __vla_expr0 = 5
> (int) i = 5
> (int [81]) MyArray = {
>   [0] = 5
>   [1] = 5
>   [2] = 5
>   [3] = 5
>   [4] = 5
>   [5] = 0
>   [6] = -136481184
>   [7] = 32767
>   [8] = -8408
>   [9] = 32767
>   [10] = -8544
>   [11] = 32767
>   [12] = 1
>   [13] = 5
>   [14] = 5
>   [15] = 0
>   [16] = -8512
>   [17] = 32767
>   [18] = 0
>   [19] = 5
>   [20] = -8432
>   [21] = 32767
>   [22] = 4195641
>   [23] = 0
>   [24] = -8208
>   [25] = 32767
>   [26] = 0
>   [27] = 0
>   [28] = 4195664
>   [29] = 0
>   [30] = -140485737
>   [31] = 32767
>   [32] = 0
>   [33] = 32
>   [34] = -8200
>   [35] = 32767
>   [36] = 0
>   [37] = 1
>   [38] = 4195616
>   [39] = 0
>   [40] = 0
>   [41] = 0
>   [42] = -1953144313
>   [43] = 1284291557
>   [44] = 4195248
>   [45] = 0
>   [46] = -8208
>   [47] = 32767
>   [48] = 0
>   [49] = 0
>   [50] = 0
>   [51] = 0
>   [52] = 1064657415
>   [53] = -1284291430
>   [54] = 933978631
>   [55] = -1284287451
>   [56] = 0
>   [57] = 32767
>   [58] = 0
>   [59] = 0
>   [60] = 0
>   [61] = 0
>   [62] = -136423629
>   [63] = 32767
>   [64] = -136530376
>   [65] = 32767
>   [66] = 386784
>   [67] = 0
>   [68] = 0
>   [69] = 0
>   [70] = 0
>   [71] = 0
>   [72] = 0
>   [73] = 0
>   [74] = 4195248
>   [75] = 0
>   [76] = -8208
>   [77] = 32767
>   [78] = 4195290
>   [79] = 0
>   [80] = -8216
> }
> 
> 
> On Thu, Feb 13, 2020 at 3:53 PM Adrian Prantl <aprantl at apple.com>
wrote:
> Take a look at the IR clang produces for C99 variable-length arrays.
> 
> -- adrian
> 
>> On Feb 13, 2020, at 10:03 AM, Levo DeLellis via llvm-dev <llvm-dev
at lists.llvm.org> wrote:
>> 
>> Hi. I searched and the closest thing I could find was this
http://lists.llvm.org/pipermail/llvm-dev/2018-February/121348.html
>> 
>> Currently a known sized array looks and debugs as expected. I use
llvm.dbg.declare with DICompositeType tag: DW_TAG_array_type and the size field.
In my language arrays are always passed around with a pointer and size pair.
I'd like debugging to show up as nicely instead of a pointer addr with no
information about the elements. How would I do this? I don't use the C API,
I output llvm-ir directly. I was hoping I can call llvm.dbg.declare/addr/value
to specify the pointer, name and size of the variable but I really have no idea
how to pass the size to the debugger.
>> 
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

Levo DeLellis via llvm-dev

2020-Feb-17 20:25 UTC

head link

[llvm-dev] Have the debugger show an away with a dynamic size?

It looks like I wasn't careful and mixed version. I compiled with clang-9
but used lldb-6. Surprisingly this was the only error I notice when mixing
these version. I could swear I tried compiling with clang-6. I'd double
check but it appears that installing lldb-9 removed lldb(-6) from my system
Thanks for pointing me in the right direction

On Mon, Feb 17, 2020 at 11:18 AM Adrian Prantl <aprantl at apple.com>
wrote:
> That is interesting. According to LLDB's test/lang/c/vla/* frame
variable
> for a VLA is supposed to work. Frame variable is also supposed to hide the
> __vla_expr0 artificial helper variable. Is this an older LLDB from your
> system or an LLDB you built from source? If yes, would you mind filing a
> bugreport about this?
>
> thanks,
> adrian
>
> > On Feb 15, 2020, at 8:17 AM, Levo DeLellis <levo.delellis at
gmail.com>
> wrote:
> >
> > Thanks for the suggestions but it doesn't appear to be working
correctly
> for me. I tried building the below after seeing the results with
"clang -g
> -std=c99 test.c" and got the same result
> >
> > LLDB thinks MyArray is 81 elements long even though 81 and 80
doesn't
> show up anywhere in the llvm-ir (I tried again using an llvm ir file made
> by clang -g -std=c99 test.c -S -emit-llvm and clang -g test.ll)
> >
> > $ cat test.c
> > int foo(int s) {
> >     int MyArray[s];
> >     int i;
> >     for (i = 0; i < s; ++i)
> >         MyArray[i] = s;
> >     return 0;
> > }
> >
> > int main(){
> >     foo(5);
> >     return 0;
> > }
> > $ clang -g test.c
> > $ lldb ./a.out
> > (lldb) target create "./a.out"
> > Current executable set to './a.out' (x86_64).
> > (lldb) break set -f test.c -l 6
> > Breakpoint 1: where = a.out`foo + 101 at test.c:7, address >
0x0000000000400505
> > (lldb) r
> > Process 3205 launched: './a.out' (x86_64)
> > Process 3205 stopped
> > * thread #1, name = 'a.out', stop reason = breakpoint 1.1
> >     frame #0: 0x0000000000400505 a.out`foo(s=5) at test.c:7
> >    4      for (i = 0; i < s; ++i)
> >    5          MyArray[i] = s;
> >    6      return 0;
> > -> 7   }
> >    8
> >    9   int main(){
> >    10      foo(5);
> > (lldb) frame variable
> > (int) s = 5
> > (unsigned long) __vla_expr0 = 5
> > (int) i = 5
> > (int [81]) MyArray = {
> >   [0] = 5
> >   [1] = 5
> >   [2] = 5
> >   [3] = 5
> >   [4] = 5
> >   [5] = 0
> >   [6] = -136481184
> >   [7] = 32767
> >   [8] = -8408
> >   [9] = 32767
> >   [10] = -8544
> >   [11] = 32767
> >   [12] = 1
> >   [13] = 5
> >   [14] = 5
> >   [15] = 0
> >   [16] = -8512
> >   [17] = 32767
> >   [18] = 0
> >   [19] = 5
> >   [20] = -8432
> >   [21] = 32767
> >   [22] = 4195641
> >   [23] = 0
> >   [24] = -8208
> >   [25] = 32767
> >   [26] = 0
> >   [27] = 0
> >   [28] = 4195664
> >   [29] = 0
> >   [30] = -140485737
> >   [31] = 32767
> >   [32] = 0
> >   [33] = 32
> >   [34] = -8200
> >   [35] = 32767
> >   [36] = 0
> >   [37] = 1
> >   [38] = 4195616
> >   [39] = 0
> >   [40] = 0
> >   [41] = 0
> >   [42] = -1953144313
> >   [43] = 1284291557
> >   [44] = 4195248
> >   [45] = 0
> >   [46] = -8208
> >   [47] = 32767
> >   [48] = 0
> >   [49] = 0
> >   [50] = 0
> >   [51] = 0
> >   [52] = 1064657415
> >   [53] = -1284291430
> >   [54] = 933978631
> >   [55] = -1284287451
> >   [56] = 0
> >   [57] = 32767
> >   [58] = 0
> >   [59] = 0
> >   [60] = 0
> >   [61] = 0
> >   [62] = -136423629
> >   [63] = 32767
> >   [64] = -136530376
> >   [65] = 32767
> >   [66] = 386784
> >   [67] = 0
> >   [68] = 0
> >   [69] = 0
> >   [70] = 0
> >   [71] = 0
> >   [72] = 0
> >   [73] = 0
> >   [74] = 4195248
> >   [75] = 0
> >   [76] = -8208
> >   [77] = 32767
> >   [78] = 4195290
> >   [79] = 0
> >   [80] = -8216
> > }
> >
> >
> > On Thu, Feb 13, 2020 at 3:53 PM Adrian Prantl <aprantl at
apple.com> wrote:
> > Take a look at the IR clang produces for C99 variable-length arrays.
> >
> > -- adrian
> >
> >> On Feb 13, 2020, at 10:03 AM, Levo DeLellis via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >>
> >> Hi. I searched and the closest thing I could find was this
> http://lists.llvm.org/pipermail/llvm-dev/2018-February/121348.html
> >>
> >> Currently a known sized array looks and debugs as expected. I use
> llvm.dbg.declare with DICompositeType tag: DW_TAG_array_type and the size
> field. In my language arrays are always passed around with a pointer and
> size pair. I'd like debugging to show up as nicely instead of a pointer
> addr with no information about the elements. How would I do this? I
don't
> use the C API, I output llvm-ir directly. I was hoping I can call
> llvm.dbg.declare/addr/value to specify the pointer, name and size of the
> variable but I really have no idea how to pass the size to the debugger.
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>
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llvm dev - Feb 2020 - Have the debugger show an away with a dynamic size?

[llvm-dev] Have the debugger show an away with a dynamic size?

[llvm-dev] Have the debugger show an away with a dynamic size?

[llvm-dev] Have the debugger show an away with a dynamic size?