[petsc-users] FLAGS in makefile

[Satish Balay]

On Tue, 13 Sep 2016, Matthew Knepley wrote:

> On Tue, Sep 13, 2016 at 12:16 PM, Timothée Nicolas <
> timothee.nicolas at gmail.com> wrote:
> 
> > Hi all,
> >
> > I can't seem to figure out how to specify my compilation options with
> > PETSc. For my makefiles, I've always been using Petsc examples inspired
> > makefiles, just tuning them to my needs, and I have never played with
> > compilation options so far. Now, I am trying to add some compilation
> > options, but they are not taken into account by the compiler. My makefile
> > looks like this
> >
> > all: energy
> >
> >
> > include ${PETSC_DIR}/lib/petsc/conf/variables
> >
> > include ${PETSC_DIR}/lib/petsc/conf/rules
> >
> >
> > #FLAGS = -g -O0 -fbounds-check
> >
> >
> >
> >
> > MYFLAGS = -mcmodel=medium -shared-intel
> >
> >
> > OBJS =  main.o \
> >
> >         modules.o \
> >
> >         diags.o \
> >
> >         functions.o \
> >
> >         conservation.o \
> >
> >
> > EXEC = energy
> >
> >
> > main.o: modules.o \
> >
> >         functions.o \
> >
> >         conservation.o \
> >
> >         diags.o \
> >
> >
> > energy: $(OBJS)  chkopts
> >
> >         -$(FLINKER) -o $(EXEC) $(MYFLAGS) $(FLAGS) $(OBJS) $(
> > PETSC_SNES_LIB)
> >
> >
> > clean_all:
> >
> >         $(RM) $(OBJS) $(EXEC)
> >
> >
> > The compiler then executes things like
> >
> > /opt/mpi/bullxmpi/1.2.8.4/bin/mpif90 -c -fPIC -g -O3
> > -I/ccc/scratch/cont003/gen0198/lutjensh/Timothee/petsc-3.7.3/include
> > -I/ccc/scratch/cont003/gen0198/lutjensh/Timothee/
> > petsc-3.7.3/arch-linux2-c-debug/include -I/opt/mpi/bullxmpi/1.2.8.4/
> > include    -o modules.o modules.F90
> >
> >
> > without taking my variable MYFLAGS into account. What may be the reason?
> > Also, what does "chkopts" mean ?
> >
> 
> 1) You want to change CFLAGS or FFLAGS
> 
> 2) 'chkopts' is an internal check for PETSc
> 
> 3) You realize that it is very dangerous to compile with options not
> configure with.

And generally - you have to declare FFLAGS - before the 'include'
statement You can set:

FPPFLAGS - for preprocessing [or compile only flags]
FFLAGS  - for compile & link flags

For link only flags - you can add them to the link command - as you've done with MYFLAGS..

Satish