From 928cb52bf51cd915da94ea098149065af6aca18a Mon Sep 17 00:00:00 2001
From: Thomas Padioleau <thomas.padioleau@cea.fr>
Date: Tue, 5 Mar 2024 15:15:04 +0100
Subject: [PATCH] Allow to compile without the Kokkos::Serial backend

---
 CMakeLists.txt              | 5 ++++-
 include/ddc/kernels/fft.hpp | 8 ++++----
 tests/fft.cpp               | 8 ++++++++
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff48c959c..3aae10543 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -218,7 +218,10 @@ install(
 if( FFTW_FOUND )
 	target_link_libraries( DDC INTERFACE FFTW::Float )
 	target_link_libraries( DDC INTERFACE FFTW::Double )
-	target_compile_definitions(DDC INTERFACE fftw_AVAIL)
+endif()
+
+if( FFTW_FOUND AND "${Kokkos_ENABLE_SERIAL}")
+	target_compile_definitions(DDC INTERFACE fftw_serial_AVAIL)
 endif()
 
 if( FFTW_FOUND AND "${Kokkos_ENABLE_OPENMP}")
diff --git a/include/ddc/kernels/fft.hpp b/include/ddc/kernels/fft.hpp
index a86894e52..0b0d67347 100644
--- a/include/ddc/kernels/fft.hpp
+++ b/include/ddc/kernels/fft.hpp
@@ -13,7 +13,7 @@
 
 #include <Kokkos_Core.hpp>
 
-#if fftw_AVAIL
+#if fftw_serial_AVAIL || fftw_omp_AVAIL
 #include <fftw3.h>
 #endif
 
@@ -35,7 +35,7 @@
 #include <hipfft/hipfft.h>
 #endif
 
-#if fftw_AVAIL
+#if fftw_serial_AVAIL || fftw_omp_AVAIL
 static_assert(sizeof(fftwf_complex) == sizeof(Kokkos::complex<float>));
 static_assert(alignof(fftwf_complex) <= alignof(Kokkos::complex<float>));
 
@@ -145,7 +145,7 @@ struct transform_type<Kokkos::complex<T1>, Kokkos::complex<T2>>
 template <typename T1, typename T2>
 constexpr TransformType transform_type_v = transform_type<T1, T2>::value;
 
-#if fftw_AVAIL
+#if fftw_serial_AVAIL || fftw_omp_AVAIL
 // _fftw_type : compatible with both single and double precision
 template <typename T>
 struct _fftw_type
@@ -384,7 +384,7 @@ void core(
 
     if constexpr (false) {
     } // Trick to get only else if
-#if fftw_AVAIL
+#if fftw_serial_AVAIL
     else if constexpr (std::is_same_v<ExecSpace, Kokkos::Serial>) {
         _fftw_plan<Tin> plan = _fftw_plan_many_dft<Tin, Tout>(
                 kwargs.direction == ddc::FFT_Direction::FORWARD ? FFTW_FORWARD : FFTW_BACKWARD,
diff --git a/tests/fft.cpp b/tests/fft.cpp
index 856b6f2fb..2e0df5b63 100644
--- a/tests/fft.cpp
+++ b/tests/fft.cpp
@@ -191,6 +191,7 @@ struct RDimX;
 struct RDimY;
 struct RDimZ;
 
+#if fftw_serial_AVAIL
 TEST(FFTNorm, OFF)
 {
     test_fft_norm<
@@ -268,6 +269,7 @@ TEST(FFTSerialHost, R2C_3D)
             RDimY,
             RDimZ>();
 }
+#endif
 
 #if fftw_omp_AVAIL
 TEST(FFTParallelHost, R2C_1D)
@@ -332,6 +334,7 @@ TEST(FFTParallelDevice, R2C_3D)
             RDimZ>();
 }
 
+#if fftw_serial_AVAIL
 TEST(FFTSerialHost, C2C_1D)
 {
     test_fft<
@@ -364,6 +367,7 @@ TEST(FFTSerialHost, C2C_3D)
             RDimY,
             RDimZ>();
 }
+#endif
 
 #if fftw_omp_AVAIL
 TEST(FFTParallelHost, C2C_1D)
@@ -433,6 +437,7 @@ TEST(FFTParallelDevice, C2C_3D)
             RDimZ>();
 }
 
+#if fftw_serial_AVAIL
 TEST(FFTSerialHost, D2Z_1D)
 {
     test_fft<
@@ -465,6 +470,7 @@ TEST(FFTSerialHost, D2Z_3D)
             RDimY,
             RDimZ>();
 }
+#endif
 
 #if fftw_omp_AVAIL
 TEST(FFTParallelHost, D2Z_1D)
@@ -534,6 +540,7 @@ TEST(FFTParallelDevice, D2Z_3D)
             RDimZ>();
 }
 
+#if fftw_serial_AVAIL
 TEST(FFTSerialHost, Z2Z_1D)
 {
     test_fft<
@@ -566,6 +573,7 @@ TEST(FFTSerialHost, Z2Z_3D)
             RDimY,
             RDimZ>();
 }
+#endif
 
 #if fftw_omp_AVAIL
 TEST(FFTParallelHost, Z2Z_1D)