make does not applies CFLAGS settings

coltson · 12-11-2018, 03:21 PM

Hello, I currently have this makefile:

Code:

CC=g++
CFLAGS=-I -O2 -fexpensive-optimizations --fast-math -march=native
DEPS = PerformanceManager.h InputHandler.h Vec3f.h Image.h FileManager.h GeometricObjects.h TGAManager.h Plane.h Sphere.h Triangle.h Scene.h TextManager.h RayTracer.hh
OBJ = PerformanceManager.o InputHandler.o Image.o FileManager.o TGAManager.o Plane.o Scene.o TextManager.o RayTracer.o main.o

%.o: %.cpp $(DEPS)
	$(CC) -c -o $@ $< $(CFLAGS)

RayTracer: $(OBJ)
	$(CC) -lpthread -o $@ $^ $(CFLAGS)

clean:
	rm -rf *.o

and while it does work, it does not apply the compiler's optimizations on the code. And I know that due to time my program is taking to execute (around 5x slower). I remove both $(CFLAGS) and replaced it by the

Code:

-O2 -fexpensive-optimizations --fast-math -march=native

that are defined in the "CFLAGS=". So what I might be doing wrong?

Thanks for the help.

NevemTeve · 12-11-2018, 05:18 PM

Restore the original state, and quote the ouput of this:

Code:

make clean
make -n RayTracer

coltson · 12-15-2018, 02:08 PM

Quote:

Originally Posted by NevemTeve

Restore the original state, and quote the ouput of this:

Code:

make clean
make -n RayTracer

Here it goes

Quote:

make clean
rm -rf *.o
leopoldo@leopoldo-desktop:~/asmfrtSource$ make -n RayTracer
g++ -c -o PerformanceManager.o PerformanceManager.cpp
g++ -c -o InputHandler.o InputHandler.cpp
g++ -c -o Image.o Image.cpp
g++ -c -o FileManager.o FileManager.cpp
g++ -c -o TGAManager.o TGAManager.cpp
g++ -c -o Plane.o Plane.cpp
g++ -c -o Scene.o Scene.cpp
g++ -c -o TextManager.o TextManager.cpp
g++ -c -o RayTracer.o RayTracer.cpp
g++ -c -o main.o main.cpp
g++ -lpthread -o RayTracer PerformanceManager.o InputHandler.o Image.o FileManager.o TGAManager.o Plane.o Scene.o TextManager.o RayTracer.o main.o -I -O2 -fexpensive-optimizations --fast-math -march=native

Andy Alt · 12-15-2018, 03:09 PM

I'm not sure, but do you get a different result if you change CFLAGS to CXXFLAGS (or CPPFLAGS) in all three locations of your Makefile?

ehartman · 12-15-2018, 03:52 PM

Quote:

Originally Posted by coltson

%.o: %.cpp $(DEPS)
$(CC) -c -o $@ $< $(CFLAGS)

A %.o: %.cpp rule must NOT have anything behind it, so the *(DEPS) will have to be removed;
all further dependencies have to be in the recipe (the 2nd line).

Anyway, the standard flag variables for C++ compilations are CXXFLAGS or CPPFLAGS

NevemTeve · 12-16-2018, 03:50 AM

@coltson: please find out the difference between [quote] and [code] tags.

One or more of your DEPS doesn't exist that's why make cannot use your rule; instead it goes with some built-in rule like this:

Code:

%.o: %.cpp
        $(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $@ -c $<

To avoid this behaviour, you can add this line into your Makefile:

Code:

.SUFFIXES:

coltson · 12-19-2018, 03:43 AM

Quote:

I'm not sure, but do you get a different result if you change CFLAGS to CXXFLAGS (or CPPFLAGS) in all three locations of your Makefile?

Thanks, it did work.

Quote:

A %.o: %.cpp rule must NOT have anything behind it, so the *(DEPS) will have to be removed;
all further dependencies have to be in the recipe (the 2nd line).

Anyway, the standard flag variables for C++ compilations are CXXFLAGS or CPPFLAGS

Could you expand on this? I mean, is there a reason as to why that? I was following this tutorial: http://www.cs.colby.edu/maxwell/cour...als/maketutor/ Anyway, the second line would be this

Quote:

$(CC) -c -o $@ $< $(CXXFLAGS)

? In case of yes, shall I put it behind the (CXXFLAGS) ?

Quote:

One or more of your DEPS doesn't exist that's why make cannot use your rule; instead it goes with some built-in rule like this:
Code:

%.o: %.cpp
$(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $@ -c $<

To avoid this behaviour, you can add this line into your Makefile:
Code:

.SUFFIXES:

Do you mean that one of my files in the DEPS line does not exist?

NevemTeve · 12-19-2018, 03:53 AM

> > One or more of your DEPS doesn't exist that's why make cannot use your rule

> Do you mean that one of my files in the DEPS line does not exist?

Yes. (RayTracer.hh might be a suspect.)

Off: please find out the difference between [quote] and [code] tags.

bigearsbilly · 01-08-2019, 04:31 AM

You don't need to re-write all the rules for normal compilation, make has loads of rules built in. You are just getting in the way.
You don't even *need* a make file to use make rules.

Create a file called 'blah.cpp' in a directory with no make file and type 'make blah' and you will see.
'make -pns' will show you all the rules.