[cmake-developers] WG: [CMake] CMake 2.8.12.201401116 is much slower than 2.8.12.1

[Dominik Bernhardt]

> -----Urspruengliche Nachricht-----
> Von: Clinton Stimpson [mailto:clinton at elemtech.com]
> Gesendet: Dienstag, 21. Januar 2014 16:10
> An: cmake-developers at cmake.org
> Cc: Bill Hoffman; Dominik Bernhardt
> Betreff: Re: [cmake-developers] [CMake] CMake 2.8.12.201401116 is  
> much slower than 2.8.12.1
>
[...]
>>
>>
>>
>> I'm surprised how this small change added a 20% slowdown.
>> -set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_DEBUG
>> QT_DEBUG)
>> +set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS $<$<NOT:
>> $<CONFIG:Debug>>:QT_NO_DEBUG>)
>
> I tried this project on Windows with CMake master (my own build) and  
> CMake (kitware build) and CMake master was slightly faster, then  
> modifying UseQt.cmake made it slightly faster still.
>
> Dominik, if you are seeing a massive slowdown, can you narrow it down?
> It may not be generator expression related at all.
>

I just tested it again with the latest master from today. For my  
particular project the configure step with the current master takes  
290s. If I only replace the UseQt4.cmake in the master with the  
version from 2.8.12.1 the configure time goes down to 23s!!
I'm also surprised that such a tiny change results in a slowdown of  
more than 1000%. But at least in my setup this is the case.

Dominik