outline-atomics

Author: MarioSieg

CMakeLists.txt

@@ -68,3 +68,9 @@ if (${MAGNETRON_BUILD_BENCHMARKS})
     add_subdirectory(benchmark)
 endif()
 
+message(STATUS "C Compiler: ${CMAKE_C_COMPILER}")
+message(STATUS "C++ Compiler: ${CMAKE_CXX_COMPILER}")
+get_target_property(MAIN_CFLAGS magnetron COMPILE_OPTIONS)
+message(STATUS "Compilation flags: ${MAIN_CFLAGS}")
+
+message(STATUS "Configuring magnetron project for ${CMAKE_SYSTEM_PROCESSOR}... done")

cmake/allocator.cmake

@@ -7,8 +7,16 @@ option(MI_OVERRIDE "" OFF)
 option(MI_OSX_INTERPOSE "" OFF)
 option(MI_OSX_ZONE "" OFF)
 option(MI_WIN_REDIRECT "" OFF)
-option(MI_NO_USE_CXX "" ON)
-option(MI_NO_OPT_ARCH "" ON)
+option(MI_OPT_ARCH "" OFF)
 add_subdirectory(extern/mimalloc)
 target_compile_definitions(magnetron PRIVATE MAGNETRON_USE_MIMALLOC)
 target_link_libraries(magnetron mimalloc-static)
+
+if (${IS_ARM64})
+    if (NOT WIN32)
+        target_compile_options(mimalloc-static PRIVATE -moutline-atomics)
+    endif()
+endif()
+
+get_target_property(MAIN_CFLAGS mimalloc-static COMPILE_OPTIONS)
+message(STATUS "Compilation flags: ${MAIN_CFLAGS}")

cmake/compiler_config.cmake

@@ -1,5 +1,15 @@
 # (c) 2025 Mario "Neo" Sieg. <[email protected]>
 
+#[===[
+
+    -moutline-atomics
+        Outline-atomics is a gcc compilation flag that adds runtime detection on if the cpu supports atomic instructions.
+        Some older ARM CPU's such as the chip on the Raspberry PI 4 don't support atomic instructions. Using them will result in a SIGILL.
+        When the outline-atomics flag is used, the compiler will generate code that checks if the CPU supports atomic instructions at runtime.
+        CPUs that don't support atomic instructions will use the old load-exclusive/store-exclusive instructions.
+        If a different compilation flag defined an architecture that unconditionally supports atomic instructions (e.g. -march=armv8.2), the outline-atomic flag will have no effect.
+]===]
+
 message("Configuring magnetron project for ${CMAKE_SYSTEM_PROCESSOR}...")
 message("C compiler: ${CMAKE_C_COMPILER_ID}")
 
@@ -55,8 +65,11 @@ set(MAG_GCC_LINK_OPTIONS "")
 set(MAG_GCC_RELEASE_LINK_OPTIONS -flto=auto)
 
 if (${IS_ARM64})
-    set(MAG_CLANG_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -march=armv8-a)
-    set(MAG_GCC_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -march=armv8-a)
+    if (NOT WIN32)
+        add_compile_options(-moutline-atomics)
+    endif()
+    set(MAG_CLANG_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -march=armv8-a -moutline-atomics) # See beginning for file for info of -moutline-atomics
+    set(MAG_GCC_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -march=armv8-a -moutline-atomics)
 elseif (${IS_AMD64})
     set(MAG_CLANG_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -msse -msse2)
     set(MAG_GCC_COMPILE_FLAGS ${MAG_CLANG_COMPILE_FLAGS} -msse -msse2)