Update README.md

halx99 · web-flow · commit 41d5fc65ea8d · 2020-11-09T23:57:47.000+08:00
diff --git a/README.md b/README.md
@@ -1,4 +1,11 @@
 # notes
+## clang arm predefininations
+- clang -arch arm64 -E -dM - < /dev/null
+```cpp
+#define __arm64 1
+#define __arm64__ 1
+```
+
 ## python mirrors
 * http://npm.taobao.org/mirrors/python
 
