On 17/12/2015 10:50, JohnBeckett wrote:
Mike Williams:
I'll look some more into it to make the defaults on Windows
more sensible and if the code can be simplified.
Thanks all for the interesting progress. I'm trying to set up a test system
where I might be able to join in but it's a long time since I worked in C. I
don't know anything about the HAVE_xxx settings, but it appears there is a
condition where Vim's data can be corrupted and that condition is being exposed
by the particular tests being run. However, the problem is potentially more
general, and conceivably corruptions could occur in other circumstances.
While paranoia is good in development in this case I think the simplest
thing to say is that there seems to be corruption when using sort with
low max mem settings. Starting from there we'll see what any
investigation shows up. At least for now the workaround is to set
maxmem values larger than the default.
Have you reached a conclusion about whether the problem is related to a
compiler optimisation bug? My guess would be that it is not since I don't think
Steve Hall uses Visual Studio to build the Vim-without-Cream that I mentioned,
and it also shows the corruption.
It is not a compiler optimisation bug. I can reproduce the issue on
linux if I limit maxmem to 2048 and maxmemtot to 5120, the current
Windows default values for these options. It is not Windows and/or
compiler settings specific.
There has to be a clue in the fact that I have only ever seen corrupted text
after executing :sort. Presumably Vim makes an array of pointers and sorts
them. That array is being clobbered, or Vim's pointer to the array is being
overwritten. Are any unchecked memory allocations done in Vim's sort?
That is a good initial working theory. The maxmem setting will cause
VIM to recover memory and off the cuff it sounds like this is leaving
dangling pointers which are then being used and just so happen to keep
pointing to allocated memory so we don't see a crash, just random data.
This will be a 2 cups of tea problem ...
TTFN
Mike
--
Don't laugh at my coffee, you will be old and weak someday too.
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