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

Clinton Stimpson clinton at elemtech.com
Tue Jan 21 10:09:33 EST 2014


On Thursday, January 16, 2014 08:41:58 AM Clinton Stimpson wrote:
> On Thursday, January 16, 2014 10:14:32 AM Bill Hoffman wrote:
> > Moving this to cmake-developers list:
> > 
> > On 1/16/2014 9:55 AM, Clinton Stimpson wrote:
> > > On one of my projects, I see ~3.0 seconds for CMake 2.8.12 and ~3.8
> > > seconds
> > > for CMake master.  I don't have an idea why, but with my test, it
> > > doesn't
> > > see like "much" slower.
> > 
> > 3.8 from 3.0 is much slower in my book....  :)
> > 
> > change it to minutes... 3 minutes vs 3.8 minutes is a big jump...
> > 
> > Looking at the test timing on the bootstrap test on a slow machine, this
> > seems to be a point that got slower:
> > 
> > http://open.cdash.org/testDetails.php?test=229000913&build=3172685   885
> > seconds
> > http://open.cdash.org/testDetails.php?test=229192425&build=3173776   902
> > seconds
> > 
> > -Bill
> 
> For this one project I got 3.0 seconds -> 3.8 seconds.
> I narrowed it down to this commit:
> 
> commit 2509c7678feb2efab79a384fd0b0b35cee8d02b0
> Author: Stephen Kelly <steveire at gmail.com>
> Date:   Mon Jan 13 13:04:03 2014 +0100
>     Qt4: Use generator expression in COMPILE_DEFINITIONS (#14692)
> 
> 
> 
> 
> 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.

-Clint



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