[Qt-interest] Qt 4.5.1 Windows GROWS 4Gb+

[Trond Kjernaasen]

Hi,

Bernd Brandstetter wrote:
> On Wednesday 20 May 2009, Miguel Cardenas wrote:
> 
>> I got a new problem compiling Qt 4.5.1 on Windows, it grows and grows
>> while compiling until the hard disk is full and 'nmake' aborts because
>> 'insuficient disk space', and checking the Qt tree it is 4.6Gb!!!!!!!!!!
> 
> Yes, I recently did the same and was astonished that 6GB of free disk space 
> weren't enough for a debug-and-release build. The "problem" is that 
> MSVC2008 uses some special optimization technique which results in 
> terribly large object files especially in release builds. In order to 
> change this, you could edit mkspecs/win32-msvc2008/qmake.conf and remove 
> the switch -GL from QMAKE_CFLAGS_RELEASE. This brings the object file size 
> down to a modest level (and saves quite some time in the linking process - 
> linking the WebKit DLL took almost half an hour on my box).

Be aware that removing the MSVC link-time optimizations will have a 
performance impact. We've measured upto 10-13% speed increase in e.g. 
the raster paint engine, by just using these optimization flags.

One of the main causes for this speed difference is that inline function 
calls between modules (e.g. between QtCore and QtGui) won't be inlined, 
unless you have link-time optimizations turned on (see 
http://msdn.microsoft.com/en-us/library/0zza0de8.aspx - the compile 
switch is /GL and the linker switch is /LTCG).

The only other option is to do a static compile (without the switches), 
which yields almost the same results.

Regards,
--
Trond K.