c++ - How to build in release mode with optimizations in GCC?

Question

What are the specific options I would need to build in "release mode" with full optimizations in GCC? If there are more than one option, please list them all. Thanks.

Answer 1

Here is a part from a Makefile that I use regularly (in this example, it's trying to build a program named foo).

If you run it like $ make BUILD=debug or $ make debug then the Debug CFLAGS will be used. These turn off optimization (-O0) and includes debugging symbols (-g).

If you omit these flags (by running $ make without any additional parameters), you'll build the Release CFLAGS version where optimization is turned on (-O2), debugging symbols stripped (-s) and assertions disabled (-DNDEBUG).

As others have suggested, you can experiment with different -O* settings dependig on your specific needs.

ifeq ($(BUILD),debug)   
# "Debug" build - no optimization, and debugging symbols
CFLAGS += -O0 -g
else
# "Release" build - optimization, and no debug symbols
CFLAGS += -O2 -s -DNDEBUG
endif

all: foo

debug:
    make "BUILD=debug"

foo: foo.o
    # The rest of the makefile comes here...