Re: Confusing problem involving uint64_t bitops

  • From: Mike Pall <mike-1502@xxxxxxxxxx>
  • To: luajit@xxxxxxxxxxxxx
  • Date: Sat, 7 Feb 2015 22:20:51 +0100

Luke Gorrie wrote:
> Just wanted to report a mysterious issue that we are seeing with LuaJIT
> v2.1 version 392b6c9 (from May) but not with v2.1 HEAD today. I am not sure
> if this is a bug that was fixed in LuaJIT, or a bug in the code I am
> posting, or a bug elsewhere e.g. heap corruption making something weird
> happen. Looking at the commit log it is not obvious that this is due to any
> bug that was fixed.

The only thing that *might* have any relevance would be commit
c75c62b4. Maybe check this commit vs. the commit just before.

Otherwise, bisecting is the only alternative. But that's tricky
for a problem that doesn't easily reproduce. Pretty much anything,
including minor changes to the memory layout, may have an
influence on the reproducibility of these kind of bugs. Doesn't
matter whether they are in LuaJIT or the app itself.

> Thoughts welcome. It is no problem to upgrade to the latest v2.1 but I
> don't know if that is actually "the fix" or not.

Well, yes, it'd feel safer if we could rule out that the problem
still lingers in the code.


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