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pleriche / FastMM4

A memory manager for Delphi and C++ Builder with powerful debugging facilities
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Strange stacktrace when detecting memory leak on x64 compiled application #56

Open UKobsa opened 6 years ago

UKobsa commented 6 years ago

Hi,

I created a small Delphi XE10.2 application explicitly using FastMM4 and memory leak detection on debug mode. It creates a simple memory leak. When compiling for Win32, the memory log looks fine:

A memory block has been leaked. The size is: 36

This block was allocated by thread 0x1398, and the stack trace (return addresses) at the time was:
419C66 [FastMM4][DebugAllocMem$qqri]
4070B2 [System.pas][System][AllocMem$qqri][4701]
642E75 [Unit1.pas][Unit1][TForm1.Button1Click][30]
591EE9 [Vcl.Controls.pas][Vcl.Controls][Controls.TControl.Click][7454]
5A9847 [Vcl.StdCtrls.pas][Vcl.StdCtrls][Stdctrls.TCustomButton.Click][5449]
5AA355 [Vcl.StdCtrls.pas][Vcl.StdCtrls][Stdctrls.TCustomButton.CNCommand][5910]
591979 [Vcl.Controls.pas][Vcl.Controls][Controls.TControl.WndProc][7338]
7750702C [GetWindowLongW]
77507038 [GetWindowLongW]
77512420 [NotifyWinEvent]
75028D07 [Unknown function at DPA_Merge]

But when compiling for Win64, the same result looks really strange:

A memory block has been leaked. The size is: 40

This block was allocated by thread 0xB44, and the stack trace (return addresses) at the time was:
426EE9 [FastMM4][_ZN7Fastmm411DebugGetMemEx]
427405 [FastMM4][_ZN7Fastmm413DebugAllocMemEx]
409380 [System.pas][System][_ZN6System8AllocMemEx][4672]
7546A4 [Unit1.pas][Unit1][_ZN5Unit16TForm112Button1ClickEPN6System7TObjectE][30]
64C9B3 [Vcl.Controls.pas][Vcl.Controls][_ZN3Vcl8Controls8TControl5ClickEv][7454]
67001B [Vcl.StdCtrls.pas][Vcl.StdCtrls][_ZN3Vcl8Stdctrls13TCustomButton5ClickEv][5449]
670F44 [Vcl.StdCtrls.pas][Vcl.StdCtrls][_ZN3Vcl8Stdctrls13TCustomButton9CNCommandERN6Winapi8Messages10TWMCommandE][5910]
40DA85 [System.pas][System][_ZN6System7TObject8DispatchEPv][17790]
64C2A0 [Vcl.Controls.pas][Vcl.Controls][_ZN3Vcl8Controls8TControl7WndProcERN6Winapi8Messages8TMessageE][7338]
6530B0 [Vcl.Controls.pas][Vcl.Controls][_ZN3Vcl8Controls11TWinControl7WndProcERN6Winapi8Messages8TMessageE][10209]
66FA65 [Vcl.StdCtrls.pas][Vcl.StdCtrls][_ZN3Vcl8Stdctrls14TButtonControl7WndProcERN6Winapi8Messages8TMessageE][5286]

Where do that strange characters come from? Is this a known problem? And howto fix it (or where to look for it)?

kind regards, Ulrich

GunSmoker commented 5 years ago

Those are mangled names. Mangling includes function's prototype info in text name (e.g. arguments, types, etc.). AFAIK, FastMM does not have any code which can unmangle names. Basically, it reads what is written in .map file. If you recompile FastMM with 3rd party support (e.g. EurekaLog, madExcept, JCL) - then 3rd party code MAY unmangle names for you (depending on how you compile your project). You can also disable mangling in linker options for your project.