Re: Circular dependency dropped warning from make in relating to CUDA code

[Ralf Wildenhues]

Hello Adam,

* Adam Mercer wrote on Fri, Jun 26, 2009 at 09:23:03PM CEST:
> make: Circular CudaChisq.cu <- CudaChisq.cu.c dependency dropped.
> 
> The following rule is used to generate the .c file from the .cu source:
> 
> CudaChisq.cu.c: CudaChisq.cu
>       nvcc -cuda --host-compilation=c $(INCLUDES) $(CPPFLAGS) --output-file 
> $@ $<
> 
> and I think that this is the source of the dependency warning. Does
> anyone know how I can "fix" this warning?

Why not name the product file CudaChisq.c rather than CudaChisq.cu.c?
The problem here is that the other half of the circle comes from the
make-internal rule `%: %.c' for compiling single-source programs.
I guess you can also avoid it with `make -r', but that may have other,
unwanted consequences.

(Note also that using $< in target rules is not portable to non-GNU
make).

Here's what I would do:

NVCC = nvcc
NVCFLAGS = -cuda --host-compilation=c
SUFFIXES = .cu .c
.cu.c:
        $(NVCC) $(NVCFLAGS) $(INCLUDES) $(CPPFLAGS) --output-file $@ $<

and then list *.cu files in automake *_SOURCES variables instead of the
*.c files.  You can list *.c files in EXTRA_DIST if you want to have
them distributed (which implies that the output of nvcc should be
portable, which I don't know whether it is the case).

Hope that helps.

Cheers,
Ralf