[fpc-pascal] Memory leaks in FPC 2.3.1 SVN 13188

[Bruce Tulloch]

I think I've nailed and example of the problem; when Copy() is called
with the result of another Copy() the reference count for the returned
array is not managed correctly when compiled with -MDelphi.

A trivial example program, copytest.pas:

    program copytest;

    var
    S, D : array of Integer;
 
    begin
      SetLength(S,4000);
      D := Copy(Copy(S));
    end.

which when compiled with:

    fpc -MDelphi -gl -gh copytest.pas

and run produces the following:

    lenin:$ ./copytest
    Heap dump by heaptrc unit
    3 memory blocks allocated : 48024/48024
    2 memory blocks freed     : 32016/32016
    1 unfreed memory blocks : 16008
    True heap size : 262144
    True free heap : 246048
    Should be : 246072
    Call trace for block $B7F4BF50 size 16008
       $080480EA  main,  line 8 of copytest.pas
       $080657A7

I hope this helps diagnose what's happening here.

Note that if compiled without -MDelphi it works correctly but in our
case we need to use -MDelphi because our application is also built
with Delphi and Kylix3.

Cheers, Bruce.

Jonas Maebe wrote:
>
> On 25 May 2009, at 10:30, Bruce Tulloch wrote:
>
>> PS: does the attribute "compilerproc" mean the function is defined to be
>> called by the compiler implicitly? We have rebuilt the FPC RTL with
>> debug enabled to further diagnose what's happening here (which is why we
>> came across it).
>
> It means that the procedure becomes invisible to regular Pascal code,
> and that it gets a particular internal symbol name. Such routines are
> indeed called implicitly by the compiler for various purposes.
>
>
> Jonas
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