Member access within misaligned address after threaded allocator patch

[planetis-m]

What happened?

const
  cacheLineSize = 64

type
  SpscQueue = object
    cachedHead {.align(cacheLineSize).}: int

proc main =
  let a = cast[ptr SpscQueue](allocShared(sizeof(SpscQueue)))
  assert a[].cachedHead == 0
  deallocShared(a)

main()

compile on devel (implies --threads:on --mm:orc) with:

nim c -t:"-fsanitize=address,undefined" -l:"-fsanitize=address,undefined" -d:nosignalhandler -d:release -g tbug

Nim Version

Nim Compiler Version 1.7.3 [Linux: amd64]
Compiled at 2022-11-17
Copyright (c) 2006-2022 by Andreas Rumpf

git hash: 1707bc4
active boot switches: -d:release --gc:markAndSweep

Current Standard Output Logs

tbug.nim:13:16: runtime error: store to misaligned address 0x7f6b3c860050 for type 'struct tyObject_SpscQueue__aotEC3Ym48dzfCy9crhmi6A', which requires 64 byte alignment
0x7f6b3c860050: note: pointer points here
 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^ 
tbug.nim:27:147: runtime error: member access within misaligned address 0x7f6b3c860050 for type 'struct tyObject_SpscQueue__aotEC3Ym48dzfCy9crhmi6A', which requires 64 byte alignment
0x7f6b3c860050: note: pointer points here
 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^

Expected Standard Output Logs

No response

Possible Solution

No response

Additional Information

This is a regression from #20492

[ringabout]

Hello @planetis-m, how could allocator know the existence of align attributes? At least -d:useMalloc never works. I don't understand why the program in that issue works with arc in 1.6.8. It doesn't work with refc in every version. See also https://stackoverflow.com/questions/19251360/attribute-alignedx-doesnt-work-on-dynamic-allocations

> choosenim 1.6.8
> nim c -t:"-fsanitize=address,undefined" -l:"-fsanitize=address,undefined" -d:nosignalhandler -d:release -g --threads:on -r test.nim

runtime error: member access within misaligned address 0x7f990538f050 for type 'struct tyObject_SpscQueue__GdNFJyrnCtCyCf83SImlrA', which requires 64 byte alignment
0x7f990538f050: note: pointer points here
 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00

[planetis-m]

I am sorry I can't answer any of those questions, I asked in the same in #internals before: https://discord.com/channels/371759389889003530/768367394547957761/1036011004812861470 You're correct though and I was wrong -d:useMalloc throws error as well.

[ringabout]

cc @Araq