Segmentation Fault in rakudo 2016.08.1-55-gb1c444f built on MoarVM version 2016.08

[l4mbd0x]

Hi, I've implemented a simple bubbleSort and if I use large file inputs it gives this error.
bubbleSort alg: http://bpaste.net/show/3f41f8ec1ce4
example input: http://bpaste.net/show/0f4b8a2f8eaa
The error is happening in bubbleSort.

[niner]

100 % reproducible. gdb gives me:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff78e99c0 in MVM_coerce_istrue (tc=0x6037c0, obj=0xeb9d30, res_reg=0x0, true_addr=0x7ffff5c6ed6e "\207\001\023", false_addr=0x7ffff5c6ed1a "\a", flip=1 '\001') at src/core/coerce.c:33
33              switch (bs == NULL ? MVM_BOOL_MODE_NOT_TYPE_OBJECT : bs->mode) {
(gdb) bt
#0  0x00007ffff78e99c0 in MVM_coerce_istrue (tc=0x6037c0, obj=0xeb9d30, res_reg=0x0, true_addr=0x7ffff5c6ed6e "\207\001\023", false_addr=0x7ffff5c6ed1a "\a", flip=1 '\001')
    at src/core/coerce.c:33
#1  0x00007ffff78cdee8 in MVM_interp_run (tc=tc@entry=0x6037c0, initial_invoke=0x48000000000001, invoke_data=0x0) at src/core/interp.c:242
#2  0x00007ffff798e9b9 in MVM_vm_run_file (instance=0x603010, filename=0x7fffffffdd6e "/home/nine/rakudo/install/share/perl6/runtime/perl6.moarvm") at src/moar.c:304
#3  0x00000000004010ab in main (argc=8, argv=0x7fffffffd718) at src/main.c:191
(gdb) p bs
$1 = (MVMBoolificationSpec *) 0x48000000000001
(gdb) p *obj
$2 = {header = {sc_forward_u = {forwarder = 0xffffffff00000019, sc = {sc_idx = 25, idx = 4294967295}, st = 0xffffffff00000019}, owner = 42458928, flags = 0, size = 0}, st = 0x7ffff51432f0}
(gdb) p *(obj->st)
$3 = {header = {sc_forward_u = {forwarder = 0x0, sc = {sc_idx = 0, idx = 0}, st = 0x0}, owner = 1, flags = 0, size = 72}, REPR = 0xe56aa0, REPR_data = 0x0, size = 4111741752, 
  type_check_cache_length = 32767, mode_flags = 0, type_check_cache = 0x287dee8, method_cache = 0x611d50, type_cache_id = 0, container_spec = 0x0, container_data = 0x0, 
  boolification_spec = 0x48000000000001, hll_owner = 0x6063b0, hll_role = 21586488, invoke = 0x7ffff5142ef0, invocation_spec = 0x7ffff51432f0, WHAT = 0x333df60, WHO = 0x0, HOW = 0x0, 
  paramet = {ric = {parameterizer = 0x0, lookup = 0x38000000000001}, erized = {parametric_type = 0x0, parameters = 0x38000000000001}}, HOW_sc = 0xe56620, HOW_idx = 0, method_cache_offset = 0, 
  method_cache_sc = 0x22a4b90, debug_name = 0xe58e98 "\031"}
(gdb) l
28      void MVM_coerce_istrue(MVMThreadContext *tc, MVMObject *obj, MVMRegister *res_reg,
29              MVMuint8 *true_addr, MVMuint8 *false_addr, MVMuint8 flip) {
30          MVMint64 result = 0;
31          if (!MVM_is_null(tc, obj)) {
32              MVMBoolificationSpec *bs = obj->st->boolification_spec;
33              switch (bs == NULL ? MVM_BOOL_MODE_NOT_TYPE_OBJECT : bs->mode) {
34                  case MVM_BOOL_MODE_CALL_METHOD: {
35                      MVMObject *code = MVM_frame_find_invokee(tc, bs->method, NULL);
36                      MVMCallsite *inv_arg_callsite = MVM_callsite_get_common(tc, MVM_CALLSITE_ID_INV_ARG);
37                      if (res_reg) {

[moritz]

valgrind output:

Invalid read of size 4
   at 0x4FAFA50: MVM_coerce_istrue (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x4F9764F: MVM_interp_run (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x5053FD8: MVM_vm_run_file (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x400FBE: main (in /home/mlenz/p6/rakudo/install/bin/moar)
 Address 0x48000000000009 is not stack'd, malloc'd or (recently) free'd


Process terminating with default action of signal 11 (SIGSEGV)
 General Protection Fault
   at 0x4FAFA50: MVM_coerce_istrue (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x4F9764F: MVM_interp_run (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x5053FD8: MVM_vm_run_file (in /home/mlenz/p6/rakudo/install/lib/libmoar.so)
   by 0x400FBE: main (in /home/mlenz/p6/rakudo/install/bin/moar)

Here's the script reproduced, in case the paste bin doesn't like us:

#!/usr/bin/perl6
# bubble sorting algorithm, time complexities (Best = n, Average = n², Worst = n²)

my $name = @*ARGS.pop;
sub store($name) { 
        my @tmp; for "$name.txt".IO.words -> $word { @tmp.push($word); }; return @tmp; 
}
sub bubbleSort(@tmp) {
        for ^@tmp -> $i { for $i ^..^ @tmp -> $j { @tmp[$j] < @tmp[$i] and @tmp[$i,$j] = @tmp[$j,$i]; } }
}

my @array = store $name;
bubbleSort @array;

The input data is the output of seq 0 4999.

[l4mbd0x]

Some findings:

1. After running the code again a few times without touching the code it generates another error report:
   Internal error: invalid thread ID 58765088 in GC work pass

2. After looking at each individual part of the code I found out that the first '^' of the expression: $i ^..^ @tmp is the reason for the issue.

3. Instead of $i ^..^ @tmp change it to ($i+1)..^ @tmp and semantically it won't change the result, but won't give any errors. Wouldn't it be the implementation of '^' for the lower boundary of the range the cause of this issue?