Re[3]: [Gc]: GC_mark_stack_bottom interpreted as heap pointer? (#21)

Ivan Maidanski ivmai at mail.ru
Sun Sep 15 01:01:32 PDT 2013


 Fixed Stefan's email

Sun, 15 Sept 2013, 11:52 +04:00 from Ivan Maidanski <ivmai at mail.ru>:
>Hi Stefan,
>
>I moved GC_mark_stack* pointers to GC_arrays: 
>* master:  https://github.com/ivmai/bdwgc/commit/efd5d4945a51a73dd9df42fae8a9f8e809287b4e
>* release-7_2:  https://github.com/ivmai/bdwgc/commit/a7a5666
>
>As I cannot reproduce the bug (on x86), so I can't check whether this change fixes the issue.
>I've not noticed any change in performance.
>
>Regards,
>Ivan
>
>Mon, 26 Aug 2013, 21:07 UTC from "Boehm, Hans" <hans.boehm at hp.com>:
>>This suggests to me that we might want to move GC_mark_stack_limit into _GC_arrays, so that it's not traced from.  I don't think that should have adverse performance impact, but I'm not 100% sure.
>>
>>Hans
>>
>>
>>--------------------
>>
>>From: Stefan Ring [mailto:notifications at github.com] 
>>Sent: Sunday, August 25, 2013 5:19 AM
>>To: ivmai/bdwgc
>>Subject: Re: [bdwgc] GC_mark_stack_bottom interpreted as heap pointer? (#21)
>>
>>I've just tried to reproduce this using a more recent version – ca89b8c –, as I could not remember exactly what I did back then.
>>I compile with KEEP_BACK_PTRS and call GC_generate_random_backtrace() at every step. After a while, most of these traces will say:
>>[...]
>>0x663f80 (tests/middle.c:114, sz=24, NORMAL)
>>Reachable via 241 levels of pointers from offset 8 in object:
>>0x663030 (tests/middle.c:114, sz=24, NORMAL)
>>Reachable via 242 levels of pointers from root at 0x601388
>>And what lives at 0x601388?
>>(gdb) x/1gx 0x601388
>>0x601388 <GC_mark_stack_limit>: 0x0000000000663000
>>So I'm not sure which one of these GC_mark_stack* variables it was last time, but this is what I'm getting now.
>>>>Reply to this email directly or view it on GitHub.
>>
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