[Mono-dev] sgen crash on x86_64 (when using libmono from Wine)

[Paul Gofman]

Hi,

while working with 64-bit mono under Wine (using libmono x64 dll) I came
through a problem with SGen garbage collector crashing on either from
finalizer thread or seemingly every time some garbage collection already
happened before. Finally I found the problem in sgen-marksweep.c:
bitcount(mword) implementation. I am attaching a patch which fixes it
for me.
    The problem is only in libmono, mono 64 bit standalone executable
does not have it. I am attaching a trivial test case which I finally
used to isolate the problem (testprint.cs). If compile it with: 'mcs
gccollect.cs -platform:x64', and then run with wine64 on a 64-bit
wineprefix, there is a native SIGSEGV in second GC collect. I used
vanilla wine 1.9.3 to reproduce the issue. Compiling test case with
-platform:x64 is important as otherwise it will be run as 32-bit process
for which the problem does not exist.
    Could you please advice if this (or similar) patch can somehow be
pushed upstream?

Thanks,
    Paul.
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