On 05 Apr 2009, at 00:40, JoshyFun wrote:
If a virtual method of a class is not used at all in the programm will the compiler remove it from the executable ?
If you use FPC 2.3.1 with whole-program optimization and the compiler can prove that it is never callable: yes. See http://wiki.freepascal.org/Whole_Program_Optimization for more information. In case this is in relation to the thread on the Lazarus list about the big executables: note that it has only a limited effect on Lazarus programs, because almost all linked LCL code can potentially be executed (due to the way the LCL is constructed). In fact, I think most savings there come from making a number of virtual method calls non-virtual, rather than from throwing away unreachable code.
The internal linker can also do it (only throwing away virtual method calls, not turning virtual method calls into static ones), but only on Windows platforms. It is however not currently enabled in the compiler, because the changes break the external linker. It should therefore be turned into a command line option (along with a check that produces an error if you try to link a unit compiled with the option using the external linker), but that hasn't been done yet.
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