[Issue 20862] Segfault on repeated GC.qalloc calls

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20862

--- Comment #1 from moonlightsentinel at disroot.org ---
Full stack trace:

Program received signal SIGSEGV, Segmentation fault.
_D2gc4impl12conservativeQw3Gcx10smallAllocMFNbmKmkxC8TypeInfoZPv (this=...,
ti=0x7ffffffeda68, bits=0,
    alloc_size=@0x7ffffffedae8: 16, size=16) at
src/gc/impl/conservative/gc.d:1686
1686            auto biti = (p - pool.baseAddr) >> pool.shiftBy;
(gdb) bt
#0  _D2gc4impl12conservativeQw3Gcx10smallAllocMFNbmKmkxC8TypeInfoZPv (this=...,
ti=0x7ffffffeda68, bits=0,
    alloc_size=@0x7ffffffedae8: 16, size=16) at
src/gc/impl/conservative/gc.d:1686
#1  0x000000000807ff73 in
_D2gc4impl12conservativeQw14ConservativeGC__T9runLockedS_DQCeQCeQCcQCnQBs12mallocNoSyncMFNbmkKmxC8TypeInfoZPvS_DQEgQEgQEeQEp10mallocTimelS_DQFiQFiQFgQFr10numMallocslTmTkTmTxQCzZQFcMFNbKmKkKmKxQDsZQDl
(this=0x84ac0a0,
    _param_3=@0x7ffffffedb08: 0x0, _param_2=@0x7ffffffedae8: 16,
_param_1=@0x7ffffffedb10: 0, _param_0=@0x7ffffffedb18: 16)
    at src/gc/impl/conservative/gc.d:1627
#2  0x0000000008072bcf in
_D2gc4impl12conservativeQw14ConservativeGC6qallocMFNbmkxC8TypeInfoZS4core6memory8BlkInfo_
(
    this=0x84ac0a0, __HID14=0x7ffffffedbf0, ti=0x0, bits=0, size=16) at
src/gc/impl/conservative/gc.d:417
#3  0x000000000803f283 in gc_qalloc (__HID19=0x7ffffffedbf0, sz=16, ba=0,
ti=0x0) at src/gc/proxy.d:36
#4  0x000000000803ed77 in
_D4core6memory2GC6qallocFNaNbmkxC8TypeInfoZSQBqQBo8BlkInfo_
(__HID3=0x7ffffffedbf0, ti=0x0, ba=0,
    sz=16) at src/core/memory.d:523
#5  0x000000000803eb55 in D main () at d_do_test.d:11

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