trying to build the examples fails

[benvanwerkhoven]

I tried the following:

cd examples
mkdir build
cd build
cmake ..
make

And got the following error:

[ 25%] Building CUDA object vector_add/CMakeFiles/kernel_float_vecadd.dir/main.cu.o
In file included from /home/ben/documents/kernel_tuner/kernel_float/examples/vector_add/main.cu:6:
/home/ben/documents/kernel_tuner/kernel_float/single_include/kernel_float.h:75:44: error: missing binary operator before token "("
   75 | #if defined(__has_builtin) && __has_builtin(__builtin_assume_aligned) && 0
      |                                            ^
make[2]: *** [vector_add/CMakeFiles/kernel_float_vecadd.dir/build.make:77: vector_add/CMakeFiles/kernel_float_vecadd.dir/main.cu.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:116: vector_add/CMakeFiles/kernel_float_vecadd.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

In my first attempt at the above the compiler complained that it could not find the kernel_float.h header. So I've added that to make CPATH and removed the build directory and restarted all the steps outlined above to finally get this error.

[benvanwerkhoven]

This is the full CMAKE output, there are a few warnings as well:

CMake Warning (dev) in CMakeLists.txt:
  No project() command is present.  The top-level CMakeLists.txt file must
  contain a literal, direct call to the project() command.  Add a line of
  code such as

    project(ProjectName)

  near the top of the file, but after cmake_minimum_required().

  CMake is pretending there is a "project(Project)" command on the first
  line.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  cmake_minimum_required() should be called prior to this top-level project()
  call.  Please see the cmake-commands(7) manual for usage documentation of
  both commands.
This warning is for project developers.  Use -Wno-dev to suppress it.

-- The C compiler identification is GNU 9.4.0
-- The CXX compiler identification is GNU 9.4.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- The CUDA compiler identification is NVIDIA 12.3.107
-- Detecting CUDA compiler ABI info
-- Detecting CUDA compiler ABI info - done
-- Check for working CUDA compiler: /usr/local/cuda/bin/nvcc - skipped
-- Detecting CUDA compile features
-- Detecting CUDA compile features - done
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found CUDA: /usr/local/cuda (found version "12.3")
CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 3.26)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring done (20.1s)
-- Generating done (0.7s)
-- Build files have been written to: /home/ben/documents/kernel_tuner/kernel_float/examples/build
(py311) ben@benwerklaptop:~/documents/kernel_tuner/kernel_float/examples/build$ make
[ 25%] Building CUDA object vector_add/CMakeFiles/kernel_float_vecadd.dir/main.cu.o
In file included from /home/ben/documents/kernel_tuner/kernel_float/examples/vector_add/main.cu:6:
/home/ben/documents/kernel_tuner/kernel_float/single_include/kernel_float.h:75:44: error: missing binary operator before token "("
   75 | #if defined(__has_builtin) && __has_builtin(__builtin_assume_aligned) && 0
      |                                            ^
make[2]: *** [vector_add/CMakeFiles/kernel_float_vecadd.dir/build.make:77: vector_add/CMakeFiles/kernel_float_vecadd.dir/main.cu.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:116: vector_add/CMakeFiles/kernel_float_vecadd.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

It seems the CMakelists.txt file may not be the 'top-level' CMakelists.txt file. I first tried to build the top-level file but that did not do anything it seemed. At least I don't end up with the examples somewhere in the build directory.

[benvanwerkhoven]

Just tested, I get the same error when using the include directory instead of the single_include directory. I also get the error when trying to compile the example on the repo's README.

[benvanwerkhoven]

Since the line in question (line 75 of marcos.h) ends with "&& 0" I don't think the expression ever evaluates to true. I tried to apply a fix similar to the one used here: madler/spoof#2 by moving the __has_builtin() function to a nested preprocessor if. This seems to fix it.

Using
nvcc --std=c++17 -arch=sm_86 -c test.cu -o test.o
I can build the example from the Readme now.

[stijnh]

The fix looks good to me! I'm guessing different host compilers handle the __has_builtin differently.