Where can I set the -O optimization compiler option for C++ in NetBeans?

Question

When I build a Release C++ project in NetBeans, it automatically configures it with the -O2 option.

I don't see anywhere in the compiler options where I can override this value. I know it's set to -O2 because I can see the cmdlines it uses in the Build window: g++ -O2 ...

If I add -O1 into the "Additional Otions" within the compiler settings it doesn't honour it because the cmdline now becomes g++ -O1 -O2 ... and so the -O2 supersedes my own setting.

So, where in the IDE can I set the -O optimization level compile setting?

I am using GNU compile tools on Linux if that makes any difference.

Answer 1

I finally found the solution by exploring a bit more. In the dialog from the OP there is the option, 'Development Mode' which is currently set to 'Release'. There are a number of options under there and each of those correspond to different optimization levels and/or debug output compile flags:

No Flags                     -c
Debug                        -c -g
Performance Debug            -c -g -O
Test Coverage                -g -c
Diagnosable Release          -c -g -O2 
Release                      -c -O2 
Performance Release          -c -O3

Although there doesn't seem to be an option for -O1, that's basically the intended way for you to select different optimization levels in NetBeans.

Answer 2

Please look at the nbproject/Makefile-Release.mk file.

nekto@ubuntu:~/host/ex/dt-netbeans-samples-cpp-Welcome$ grep -r O2 *
nbproject/Makefile-Release.mk:  $(COMPILE.cc) -O2 -MMD -MP -MF "[email protected]" -o     ${OBJECTDIR}/welcome.o welcome.cc

It looks like the -O2 option presence in the Release configuration is the default and unchangeable, however you always can create your own build configuration (and you did as I see).

Each build configuration has its own nbproject/Makefile-<configuration name>.mk file, which contains following lines:

# CC Compiler Flags
CCFLAGS=-O1
CXXFLAGS=-O1

I've created a new configuration, made it active, and set the -O1 option above from the NetBeans properties pop-up window, C++ Compiler -> Additional Options, and my compilation line didn't contain the -O2 option. My Additional Options panel is below: