Added option to pass CPU features (e.g. vector extensions) to the compiler (GCC/Clang only for now).

SConscript

@@ -18,6 +18,20 @@ import uuid
 
 from SCons.Node import Node
 
+_GCC_CPU_FEATURES_MAP = {
+    'mmx': '-mmmx',
+    'sse': '-msse',
+    'sse2': '-msse2',
+    'sse3': '-msse3',
+    'ssse3': '-mssse3',
+    'sse4': '-msse4',
+    'sse4a': '-msse4a',
+    'sse4.1': '-msse4.1',
+    'sse4.2': '-msse4.2',
+    'avx': '-mavx',
+    'avx2': '-mavx2'
+}
+
 class TargetType(enum.Enum):
     PROGRAM = 0
     STATIC_LIBRARY = 1
@@ -918,7 +932,6 @@ if not config.get('CXX_STANDARD'):
     config['CXX_STANDARD'] = 'c++23'
 if not config.get('CXX_NO_EXCEPTIONS'):
     config['CXX_NO_EXCEPTIONS'] = False
-
 if not config.get('PREPROCESSOR_PREFIX'):
     config['PREPROCESSOR_PREFIX'] = config['PROJECT_NAME'].upper() # TODO: may be nicer?
 
@@ -1144,6 +1157,7 @@ env['SPP_TARGET_DEPENDENCIES'] = []
 env['SPP_DEPENDENCIES'] = {}
 env['SPP_RECIPES'] = {}
 env['SPP_MODULES'] = {} # maps from folder to _Module
+env['SPP_CPU_FEATURES'] = config.get('USE_CPU_FEATURES', [])
 
 env['OBJSUFFIX'] = f".{env['BUILD_TYPE']}{env['OBJSUFFIX']}"
 if variant:
@@ -1246,6 +1260,13 @@ if env['COMPILER_FAMILY'] == 'gcc' or env['COMPILER_FAMILY'] == 'clang':
         env.Append(DEPS_CXXFLAGS = ['-fsanitize=address', '-fno-omit-frame-pointer'])
         env.Append(DEPS_LINKFLAGS = ['-fsanitize=address'])
 
+    for feature in env['SPP_CPU_FEATURES']:
+        flag = _GCC_CPU_FEATURES_MAP.get(feature)
+        if flag is None:
+            _warn(None, f'Unknown or unsupported cpu feature "{feature}" for GCC/Clang.')
+        else:
+            env.Append(CCFLAGS = [flag])
+
 elif env['COMPILER_FAMILY'] == 'cl':
     cxx_version_name = {
         'c++14': 'c++14',