From 9c17e90c77ed813cc62eb1c6313fbdc4d6ffbc75 Mon Sep 17 00:00:00 2001
From: Bram Veenboer <bram.veenboer@gmail.com>
Date: Fri, 15 Aug 2025 10:30:57 +0200
Subject: [PATCH] Add AVX checks (#20)

Co-authored-by: mancini <mancini@astron.nl>
---
 CMakeLists.txt            |  1 +
 benchmarks/CMakeLists.txt |  7 +++++--
 cmake/FindAVX.cmake       | 42 +++++++++++++++++++++++++++++++++++++++
 src/CMakeLists.txt        | 11 ++++++----
 src/lookup_avx.cpp        |  1 -
 tests/CMakeLists.txt      |  8 +++++---
 6 files changed, 60 insertions(+), 10 deletions(-)
 create mode 100644 cmake/FindAVX.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ef1df5e..2faf542 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,6 +12,7 @@ option(TRIGDX_BUILD_TESTS "Build tests" ON)
 option(TRIGDX_BUILD_BENCHMARKS "Build tests" ON)
 option(TRIGDX_BUILD_PYTHON "Build Python interface" ON)
 
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake")
 configure_file(
   ${CMAKE_CURRENT_SOURCE_DIR}/cmake/trigdx_config.hpp.in
   ${CMAKE_CURRENT_BINARY_DIR}/include/trigdx/trigdx_config.hpp @ONLY)
diff --git a/benchmarks/CMakeLists.txt b/benchmarks/CMakeLists.txt
index a44e7fc..95bc091 100644
--- a/benchmarks/CMakeLists.txt
+++ b/benchmarks/CMakeLists.txt
@@ -13,8 +13,11 @@ target_link_libraries(benchmark_reference PRIVATE trigdx benchmark::benchmark)
 add_executable(benchmark_lookup benchmark_lookup.cpp)
 target_link_libraries(benchmark_lookup PRIVATE trigdx benchmark::benchmark)
 
-add_executable(benchmark_lookup_avx benchmark_lookup_avx.cpp)
-target_link_libraries(benchmark_lookup_avx PRIVATE trigdx benchmark::benchmark)
+if(HAVE_AVX)
+  add_executable(benchmark_lookup_avx benchmark_lookup_avx.cpp)
+  target_link_libraries(benchmark_lookup_avx PRIVATE trigdx
+                                                     benchmark::benchmark)
+endif()
 
 if(TRIGDX_USE_MKL)
   add_executable(benchmark_mkl benchmark_mkl.cpp)
diff --git a/cmake/FindAVX.cmake b/cmake/FindAVX.cmake
new file mode 100644
index 0000000..9fac219
--- /dev/null
+++ b/cmake/FindAVX.cmake
@@ -0,0 +1,42 @@
+include(CheckCXXSourceRuns)
+
+set(SUPPORTED_COMPILERS Clang;GNU;Intel;IntelLLVM)
+
+if(CMAKE_CXX_COMPILER_ID IN_LIST SUPPORTED_COMPILERS)
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
+    set(CMAKE_REQUIRED_FLAGS "-xHost") # ICC
+  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "IntelLLVM")
+    set(CMAKE_REQUIRED_FLAGS "-march=native") # ICX
+  else()
+    set(CMAKE_REQUIRED_FLAGS "-march=native") # GCC/Clang
+  endif()
+else()
+  message(FATAL_ERROR "Unsupported compiler: ${CMAKE_CXX_COMPILER_ID}.")
+endif()
+
+# AVX check
+check_cxx_source_runs(
+  "
+#include <immintrin.h>
+int main() {
+    __m256 a = _mm256_setzero_ps(); // AVX
+    (void) a;
+    return 0;
+}
+"
+  HAVE_AVX)
+
+if(HAVE_AVX)
+  # AVX2 check
+  check_cxx_source_runs(
+    "
+#include <immintrin.h>
+int main() {
+    __m256i a = _mm256_set1_epi32(-1);
+    __m256i b = _mm256_abs_epi32(a); // AVX2
+    (void) b;
+    return 0;
+}
+"
+    HAVE_AVX2)
+endif()
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f7eb2f2..09c01e9 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,10 +1,12 @@
 include(FetchContent)
-
-add_library(trigdx reference.cpp lookup.cpp lookup_avx.cpp)
+include(FindAVX)
+add_library(trigdx reference.cpp lookup.cpp)
 
 target_include_directories(trigdx PUBLIC ${PROJECT_SOURCE_DIR}/include)
 
-target_compile_options(trigdx PRIVATE -O3 -march=native)
+if(HAVE_AVX)
+  target_sources(trigdx PRIVATE lookup_avx.cpp)
+endif()
 
 if(TRIGDX_USE_MKL)
   find_package(MKL REQUIRED)
@@ -22,7 +24,8 @@ if(TRIGDX_USE_GPU)
 endif()
 
 if(TRIGDX_USE_XSIMD)
-  find_package(xsimd QUIET)
+  # Requires XSIMD > 13 for architecture independent dispatching
+  find_package(xsimd 13 QUIET)
   if(NOT TARGET xsimd)
     FetchContent_Declare(
       xsimd
diff --git a/src/lookup_avx.cpp b/src/lookup_avx.cpp
index b3313ff..1effba7 100644
--- a/src/lookup_avx.cpp
+++ b/src/lookup_avx.cpp
@@ -160,7 +160,6 @@ template <std::size_t NR_SAMPLES> struct LookupAVXBackend<NR_SAMPLES>::Impl {
     for (std::size_t i = 0; i < n; ++i) {
       std::size_t idx = static_cast<std::size_t>(x[i] * SCALE) & MASK;
       std::size_t idx_cos = (idx + NR_SAMPLES / 4) & MASK;
-      s[i] = lookup[idx];
       c[i] = lookup[idx_cos];
     }
 #endif
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 69992d0..bd50093 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -10,9 +10,11 @@ target_link_libraries(test_lookup PRIVATE trigdx Catch2::Catch2WithMain)
 add_test(NAME test_lookup COMMAND test_lookup)
 
 # LookupAVX backend test
-add_executable(test_lookup_avx test_lookup_avx.cpp)
-target_link_libraries(test_lookup_avx PRIVATE trigdx Catch2::Catch2WithMain)
-add_test(NAME test_lookup_avx COMMAND test_lookup_avx)
+if(HAVE_AVX)
+  add_executable(test_lookup_avx test_lookup_avx.cpp)
+  target_link_libraries(test_lookup_avx PRIVATE trigdx Catch2::Catch2WithMain)
+  add_test(NAME test_lookup_avx COMMAND test_lookup_avx)
+endif()
 
 # MKL backend test
 if(TRIGDX_USE_MKL)