Makefiles
The directory $UWHPSC/codes/fortran/multifile1 contains a Fortran code
fullcode.f90 that consists of a main program and two subroutines:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 | ! $UWHPSC/codes/fortran/multifile1/fullcode.f90
program demo
print *, "In main program"
call sub1()
call sub2()
end program demo
subroutine sub1()
print *, "In sub1"
end subroutine sub1
subroutine sub2()
print *, "In sub2"
end subroutine sub2
|
To illustrate the construction of a Makefile, we first break this up into
three separate files:
| ! $UWHPSC/codes/fortran/multifile1/main.f90
program demo
print *, "In main program"
call sub1()
call sub2()
end program demo
|
| ! $UWHPSC/codes/fortran/multifile1/sub1.f90
subroutine sub1()
print *, "In sub1"
end subroutine sub1
|
| ! $UWHPSC/codes/fortran/multifile1/sub2.f90
subroutine sub2()
print *, "In sub2"
end subroutine sub2
|
The directory $UWHPSC/codes/fortran/multifile1 contains several Makefiles
that get successively more sophisticated to compile the codes in this
directory.
In the first version we write out explicitly what to do for each file:
1
2
3
4
5
6
7
8
9
10
11
12
13
14 | # $UWHPSC/codes/fortran/multifile1/Makefile
output.txt: main.exe
./main.exe > output.txt
main.exe: main.o sub1.o sub2.o
gfortran main.o sub1.o sub2.o -o main.exe
main.o: main.f90
gfortran -c main.f90
sub1.o: sub1.f90
gfortran -c sub1.f90
sub2.o: sub2.f90
gfortran -c sub2.f90
|
In the second version there is a general rule for creating .o files from
.f90 files:
| # $UWHPSC/codes/fortran/multifile1/Makefile2
output.txt: main.exe
./main.exe > output.txt
main.exe: main.o sub1.o sub2.o
gfortran main.o sub1.o sub2.o -o main.exe
%.o : %.f90
gfortran -c $<
|
In the third version we define a macro OBJECTS so we only have to write
out this list once, which minimizes the chance of introducing errors:
1
2
3
4
5
6
7
8
9
10
11
12 | # $UWHPSC/codes/fortran/multifile1/Makefile3
OBJECTS = main.o sub1.o sub2.o
output.txt: main.exe
./main.exe > output.txt
main.exe: $(OBJECTS)
gfortran $(OBJECTS) -o main.exe
%.o : %.f90
gfortran -c $<
|
In the fourth version, we add a Fortran compile flag (for level 3
optimization) and an linker flag (blank in this example):
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 | # $UWHPSC/codes/fortran/multifile1/Makefile4
FC = gfortran
FFLAGS = -O3
LFLAGS =
OBJECTS = main.o sub1.o sub2.o
output.txt: main.exe
./main.exe > output.txt
main.exe: $(OBJECTS)
$(FC) $(LFLAGS) $(OBJECTS) -o main.exe
%.o : %.f90
$(FC) $(FFLAGS) -c $<
|
Next we add a phony target clean
that removes the files created when compiling
the code in order to facilitate cleanup. It is phony because it does not
create a file named clean.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16 | # $UWHPSC/codes/fortran/multifile1/Makefile5
OBJECTS = main.o sub1.o sub2.o
.PHONY: clean
output.txt: main.exe
./main.exe > output.txt
main.exe: $(OBJECTS)
gfortran $(OBJECTS) -o main.exe
%.o : %.f90
gfortran -c $<
clean:
rm -f $(OBJECTS) main.exe
|
Finally we add a help message so that make help says something useful:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24 | # $UWHPSC/codes/fortran/multifile1/Makefile6
OBJECTS = main.o sub1.o sub2.o
.PHONY: clean help
output.txt: main.exe
./main.exe > output.txt
main.exe: $(OBJECTS)
gfortran $(OBJECTS) -o main.exe
%.o : %.f90
gfortran -c $<
clean:
rm -f $(OBJECTS) main.exe
help:
@echo "Valid targets:"
@echo " main.exe"
@echo " main.o"
@echo " sub1.o"
@echo " sub2.o"
@echo " clean: removes .o and .exe files"
|
Fancier things are also possible, for example automatically detecting all
the .f90 files in the directory to construct the list of SOURCES
and OBJECTS:
| # $UWHPSC/codes/fortran/multifile1/Makefile7
SOURCES = $(wildcard *.f90)
OBJECTS = $(subst .f90,.o,$(SOURCES))
.PHONY: test
test:
@echo "Sources are: " $(SOURCES)
@echo "Objects are: " $(OBJECTS)
|
