How to makefile to compile to the library with two set of options

[Peng Yu]

Hi,

I'm using the implicit rules to compile the library. Suppose $(OBJS)
defines all the *.o file names and the library(.a file) I want is
libdfm.a

CXXFLAGS = -O3
all:    libdfm.a($(OBJS))

The above makefile command will compile the source code with -O3
option. Would you please show me how to compile the source code by
"-O3" and "-g" options? Thus I could end up with two versions of
library.

Thanks,
Peng