Makefile dependency rules for multiple source-object compilation - makefile

Question

I apologize if this is a somewhat noobish question, I have been searching for a while and haven't found the answer.
I am new to makefiles, and am trying to create one which compiles multiple source files in various directories into object files in a single directory and then link them.
It works, but it always recompiles all the files even if I haven't changed them. To my understanding, it should only do this if the dependencies are older than the targets. What am I doing wrong?
Here is my makefile:
CC = mpic++
CCU = nvcc
ARCH = -arch=sm_52
SOURCEDIR = ./source
SOLVERDIR = $(SOURCEDIR)/solvers
OBJECTDIR = ./bin
INCLUDE = -I./include -I/home/alexander/.openmpi/include -I/usr/local/cuda-7.5/include
LIBRARY = -L/usr/local/cuda-7.5/lib64 -lcublas -lcudart
OUT = cgsolve
CDEPS = $(OBJECTDIR)/main.o $(OBJECTDIR)/timer.o $(OBJECTDIR)/cgMPIFuncs.o
compileC: $(CDEPS)
$(CC) $(INCLUDE) -c $(SOURCEDIR)/main.cpp -o $(OBJECTDIR)/main.o
$(CC) $(INCLUDE) -c $(SOURCEDIR)/timer.cpp -o $(OBJECTDIR)/timer.o
$(CC) $(INCLUDE) -c $(SOURCEDIR)/cgMPIFuncs.cpp -o $(OBJECTDIR)/cgMPIFuncs.o
CUDEPS = $(OBJECTDIR)/BiCGStab.o $(OBJECTDIR)/CG.o $(OBJECTDIR)/solverUtil.o $(OBJECTDIR)/cudaKernels.o
compileCU: $(CUDEPS)
$(CCU) $(ARCH) $(INCLUDE) -c $(SOLVERDIR)/BiCGStab.cu -o $(OBJECTDIR)/BiCGStab.o
$(CCU) $(ARCH) $(INCLUDE) -c $(SOLVERDIR)/CG.cu -o $(OBJECTDIR)/CG.o
$(CCU) $(ARCH) $(INCLUDE) -c $(SOURCEDIR)/solverUtil.cu -o $(OBJECTDIR)/solverUtil.o
$(CCU) $(ARCH) $(INCLUDE) -c $(SOURCEDIR)/cudaKernels.cu -o $(OBJECTDIR)/cudaKernels.o
OBJDEPS = $(OBJECTDIR)/main.o $(OBJECTDIR)/BiCGStab.o $(OBJECTDIR)/CG.o $(OBJECTDIR)/solverUtil.o $(OBJECTDIR)/cudaKernels.o $(OBJECTDIR)/timer.o $(OBJECTDIR)/cgMPIFuncs.o
build:
$(CC) $(OBJDEPS) $(LIBRARY) -o $(OUT)
all: compileC compileCU build
And again, sorry if this is a repeat or something. I haven't been able to find a previous version of this question. Thanks for the help!

Answer 1

Instead of setting rules explicitly altogether, please try pattern-rule like below, also it's better to add OBJDEPS as pre-requisite for build target (then no need for compileC and compileCU, unless you want to keep those targets)
compileC: $(CDEPS)
compileCU: $(CUDEPS)
build: $(OBJDEPS)
$(CC) $^ $(LIBRARY) -o $(OUT)
$(OBJECTDIR)/%.o : $(SOURCEDIR)/%.cpp
$(CC) $(INCLUDE) -c $^ -o $#
$(OBJECTDIR)/%.o : $(SOLVERDIR)/%.cu
$(CCU) $(ARCH) $(INCLUDE) -c $^ -o $#