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.delel...@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 <apra...@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-...@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-...@lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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