How can I make my program 'weight' less

[roseicollis]

@jsulm can you explain me how to use it? I don't know how does that tools work and didn't find it in google either. Thanks!

[kshegunov]

@roseicollis
I'll start top to bottom:

• unix:!macx: LIBS += -L$PWD/../../ConfigLib/Release/ -lLib1
  means to tell qmake to generate a makefile where your libraries are located in $PWD/../../ConfigLib/Release/ and you want to link Lib1 (filename libLib1.so). unix:!macx: tells qmake to do this for all *nix systems except macx.
• INCLUDEPATH += $PWD/../../Lib1 tells qmake to add a directory for includes that is $PWD/../../Lib1
• DEPENDPATH += $PWD/../../Libs/Release tells it add a directory for resolving dependencies
• unix:!macx: PRE_TARGETDEPS += $PWD/../../Libs/Release/Lib1.a This tells qmake that you actually want an archive file (.a) linked, not a shared object (dynamic library). Again, this is done for *nix systems that are not macx.

Here is a full reference of qmake's variables.

On the second part there are two main considerations:

1. Number of linked libraries (total amount of code to be included) and their size - all that you link statically will be copied in your executable, so this is a factor for size.
2. Code generated for your executable - Your own executable might be large, the static libraries aside. For example if you have many template instantiations this will swell your executable's size. Each of the templates is expanded and then compiled as a separate class, meaning QList<int> and QList<double> are two different classes (from the compiler's and/or linker's point of view) and code will be generated for each of them.

Additionally consider @jsulm's suggestion and strip the symbols you won't need. As far as I know, this could also be done by passing -s as an additional parameter to gcc (assuming you use that compiler). The relevant qmake variables are QMAKE_CXX_FLAGS for the compiler and QMAKE_LFLAGS for the linker respectively.

I hope this helps.
Kind regards.

[roseicollis]

@kshegunov
Wow, thank you for that explanation! About adding the -s to the gcc ....How can I add it? I mean.. i use to Ctr+R to compile and run my app (if release, if debug then F5). I've searched in the project properties but didn't found where can I add it.

[jsulm]

Try QMAKE_CFLAGS += -s in your *.PRO file

[kshegunov]

@roseicollis
You're welcome. I'd use QMAKE_CXX_FLAGS += -s in the .pro file, that's why I linked the two qmake variables in my previous post.
Also as @jsulm wrote QMAKE_CFLAGS might be used as well, but I'm not a 100% sure it'll be employed by qmake when compiling C++ source, so I suggest to use the C++ specific flags.

[roseicollis]

@kshegunov, @jsulm
I've added the QMAKE_CXX_FLAGS+= -s line. Notice that my line is diferent from your s(is th eonly one recognized by my version in Qt). Before adding it, I checked my exe (which was 8.1Mib) and after adding that line and compile it again... its the same... 8.1Mib (and also checked the properties to see if the last change hour was diferent, and was everything correct).

I'll copy part of my *.pro as it may be interesting some way maybe:

QT       += core gui
QT       += network
QT       += script
QT       += date
QT       += time
QT       += xml
QMAKE_CXXFLAGS += -std=c++11
QMAKE_CXX_FLAGS += -s

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET =MyProject
TEMPLATE = app


SOURCES + =...
HEDAERS += ...
FORMS+= ...

// *My statically linked libraries here* 

unix:!macx: LIBS += -lrt
unix:!macx: LIBS += -lexpat

Thanks!
P.d: (how do you mark in red a line here in the forum? I can't find the legend :P)

[jsulm]

Did you check whether -s was really passed to gcc (in the compiler output)?

[roseicollis]

@jsulm
Well... I get this:

15:58:52: Running steps for project MyProject...
15:58:52: Configuration unchanged, skipping qmake step.
15:58:52: Starting: "/usr/bin/make" 
make: Nothing to be done for `first'.
15:58:52: The process "/usr/bin/make" exited normally.
15:58:52: Elapsed time: 00:00.

so looking on the internet to see how can I avoid the "Configuration unchanged, skipping qmake step." found that I had to remove the makefile, which makes:

16:00:14: Running steps for project MyProject...
16:00:14: Starting: "/usr/bin/qmake-qt4" /home/suser/workspace/Path/Projects/MyProject/MyProject.pro -r -spec linux-g++
Project MESSAGE: Warning: unknown QT: date
Project MESSAGE: Warning: unknown QT: time
16:00:14: The process "/usr/bin/qmake-qt4" exited normally.
16:00:14: Starting: "/usr/bin/make" 
make: Nothing to be done for `first'.
16:00:14: The process "/usr/bin/make" exited normally.
16:00:14: Elapsed time: 00:00.

And if i clean and rebuild all the project and copy a part of all the message before it ends (if it ends rebuilding, all the messages are gone), I can see:

g++ -c -pipe -std=c++11 -s -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_SCRIPT_LIB -DQT_XML_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/lib/qt4/mkspecs/linux-g++ -I../MyProject-I/usr/include/QtCore -I/usr/include/QtNetwork -I/usr/include/QtGui -I/usr/include/QtXml -I/usr/include/QtScript -I/usr/include -I../../Utils -I../../Lib1-I../../Lib2-I../../Lib3-I../../Lib4-I. -I. -I../MyProject-I. -o wp2.o ../MyProject/wpmine.cpp

Where I can see the -s param clearly on the first line, fifth space. So I understand that the compiler efectively is using the -s param.

[kshegunov]

@roseicollis
The red text is inline code, you use it by putting the text between single backticks.

This is a very strange build command. You compile in debug but set the code to be optimized (twice no less) ... that aside I don't know what further to suggest, in principle it should be working, but I've not really used it so I don't know for sure.

[jsulm]

@roseicollis To avoid "Configuration unchanged" just rebuild your project