[libcxx-commits] [libcxx] [libc++] Properly implement array cookies in the ARM ABI (PR #160182)

[Nikolas Klauser via libcxx-commits]

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@@ -30,8 +30,20 @@
 #elif _LIBCPP_ABI_FORCE_MICROSOFT
 #  define _LIBCPP_ABI_MICROSOFT
 #else
+// Windows uses the Microsoft ABI
 #  if defined(_WIN32) && defined(_MSC_VER)
 #    define _LIBCPP_ABI_MICROSOFT
+
+// 32-bit ARM uses the Itanium ABI with a few differences (array cookies, etc),
+// and so does 64-bit ARM on Apple platforms.
+#  elif defined(__arm__) || (defined(__APPLE__) && defined(__aarch64__))
+#    define _LIBCPP_ABI_ITANIUM_WITH_ARM_DIFFERENCES
+
+// Non-Apple 64-bit ARM uses the vanilla Itanium ABI
+#  elif defined(__aarch64__)
+#    define _LIBCPP_ABI_ITANIUM
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philnik777 wrote:

Is there a reason we define this separately?

https://github.com/llvm/llvm-project/pull/160182