[llvm-branch-commits] [clang] [clang] Implement function pointer signing and authenticated function calls (PR #93906)

[Akira Hatanaka via llvm-branch-commits]

================
@@ -14,10 +14,146 @@
 #ifndef LLVM_CLANG_BASIC_POINTERAUTHOPTIONS_H
 #define LLVM_CLANG_BASIC_POINTERAUTHOPTIONS_H
 
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/LangOptions.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Target/TargetOptions.h"
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
 namespace clang {
 
 constexpr unsigned PointerAuthKeyNone = -1;
 
+class PointerAuthSchema {
+public:
+  enum class Kind : unsigned {
+    None,
+    ARM8_3,
+  };
+
+  /// Hardware pointer-signing keys in ARM8.3.
+  ///
+  /// These values are the same used in ptrauth.h.
+  enum class ARM8_3Key : unsigned {
+    ASIA = 0,
+    ASIB = 1,
+    ASDA = 2,
+    ASDB = 3
+  };
+
+  /// Forms of extra discrimination.
+  enum class Discrimination : unsigned {
+    /// No additional discrimination.
+    None,
+
+    /// Discriminate using a constant value.
+    Constant,
+  };
+
+private:
+  Kind TheKind : 2;
+  unsigned IsAddressDiscriminated : 1;
----------------
ahatanak wrote:

I don't think it makes any difference on macOS or Linux, but mixing bool bitfields and unsigned bitfields can increase the size of the struct on Windows (see https://learn.microsoft.com/en-us/cpp/c-language/storage-and-alignment-of-structures?view=msvc-170). The underlying types of the enums used here are all unsigned.

I guess we should use `unsigned` as the underlying type of bitfields in `class CGPointerAuthInfo` too.

https://github.com/llvm/llvm-project/pull/93906