fix #1588 (#1590)

* fix #1588

* Fix spelling and allow glaze grouping in Cmake

* Delete avx.cmake

* glaze_DISABLE_AVX2_WHEN_SUPPORTED -> glaze_DISABLE_SIMD_WHEN_SUPPORTED

---------

Co-authored-by: Artur Bać <artur@ebasoft.com.pl>
Co-authored-by: Stephen Berry <stephenberry.developer@gmail.com>

CMakeLists.txt

@@ -50,15 +50,10 @@ if (glaze_DEVELOPER_MODE)
   include(cmake/dev-mode.cmake)
 endif()
 
-if (APPLE)
-  option(glaze_ENABLE_AVX2 "Enable AVX2 instruction set" OFF)
-else()
-  option(glaze_ENABLE_AVX2 "Enable AVX2 instruction set" ON)
-  message("Glaze is being compiled with AVX2 instructions. Set glaze_ENABLE_AVX2 to OFF if you wish to disable this.")
-endif()
-
-if (glaze_ENABLE_AVX2)
-  include(cmake/avx.cmake)
+option(glaze_DISABLE_SIMD_WHEN_SUPPORTED
+       "disable SIMD optimizations even when targets support it (e.g. AVX2)" OFF)
+if(glaze_DISABLE_SIMD_WHEN_SUPPORTED)
+  target_compile_definitions(glaze_glaze INTERFACE GLZ_DISABLE_SIMD)
 endif()
 
 option(glaze_BUILD_EXAMPLES "Build GLAZE examples" OFF)

include/glaze/json/write.hpp

@@ -8,13 +8,19 @@
 #include <ostream>
 #include <variant>
 
-#if defined(__APPLE__)
-#elif defined(_MSC_VER)
-#include <intrin.h>
-#elif defined(GLZ_USE_AVX2)
-#include <immintrin.h>
+#if !defined(GLZ_DISABLE_SIMD) && (defined(__x86_64__) || defined(_M_X64))
+    #if defined(_MSC_VER)
+        #include <intrin.h>
+    #else
+        #include <immintrin.h>
+    #endif
+
+    #if defined(__AVX2__)
+        #define GLZ_USE_AVX2
+    #endif
 #endif
 
+
 #include "glaze/core/opts.hpp"
 #include "glaze/core/reflect.hpp"
 #include "glaze/core/write.hpp"