Thanks! It's indeed a clever way. Being still curious, I am waiting for some explanation on which happens at which stage. --- On Fri, 8/28/09, Tim Prince <n8tm@xxxxxxx> wrote: > From: Tim Prince <n8tm@xxxxxxx> > Subject: Re: Debugging, optimization and profiling - which happens at which stage(s) (compilation and link) > To: "Tim" <timlee126@xxxxxxxxx> > Cc: gcc-help@xxxxxxxxxxx > Date: Friday, August 28, 2009, 1:28 PM > Tim wrote: > > Hi, > > > > In most Makefiles I have seen, CXXFLAGS is used in the > compile rule, either implicitly or explicitly. A few days > ago, however I saw a Makefile that uses CXXFLAGS in link > stage. Its compile rule is implicit which I suppose to use > CXXFLAGS as well. The Makefile is as follows: > > > > ifeq ($(STATIC),yes) > > LDFLAGS=-static -lm -ljpeg -lpng -lz > > else > > LDFLAGS=-lm -ljpeg -lpng > > endif > > > > ifeq ($(DEBUG),yes) > > OPTIMIZE_FLAG = -ggdb3 -DDEBUG > -fno-omit-frame-pointer > > else > > OPTIMIZE_FLAG = -ggdb3 -O3 > > endif > > > > ifeq ($(PROFILE),yes) > > PROFILE_FLAG = -pg > > endif > > > > CXXFLAGS = -Wall $(OPTIMIZE_FLAG) $(PROFILE_FLAG) > $(CXXGLPK) > > > > all: test > > > > test: test.o rgb_image.o > $(CXX) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) > > > > Makefile.depend: *.h *.cc Makefile > > > > > Does it mean that the optimization, debug options > or/and profiling options are necessary in both compile and > link stages? So is it better to use CXXFLAGS in link stage > too? > > > > When $(CXX) is used to drive the link step, it's entirely > appropriate to pass it the same flags used at compile time, > even though many of them will be ignored. In this > case, the flag -pg must be consistent between compile and > link steps. > I believe most C++ compilers implicitly include -lm, so > that is redundant yere. >
