[clang] [PAC][clang] Define `PointerAuthQualifier` and `PointerAuthenticationMode` (PR #84384)

[Daniil Kovalev via cfe-commits]

================
@@ -139,6 +141,168 @@ using CanQualType = CanQual<Type>;
 #define TYPE(Class, Base) class Class##Type;
 #include "clang/AST/TypeNodes.inc"
 
+/// Pointer-authentication qualifiers.
+class PointerAuthQualifier {
+  enum : uint32_t {
+    EnabledShift = 0,
+    EnabledBits = 1,
+    EnabledMask = 1 << EnabledShift,
+    AddressDiscriminatedShift = EnabledShift + EnabledBits,
+    AddressDiscriminatedBits = 1,
+    AddressDiscriminatedMask = 1 << AddressDiscriminatedShift,
+    AuthenticationModeShift =
+        AddressDiscriminatedShift + AddressDiscriminatedBits,
+    AuthenticationModeBits = 2,
+    AuthenticationModeMask = ((1 << AuthenticationModeBits) - 1)
+                             << AuthenticationModeShift,
+    IsaPointerShift = AuthenticationModeShift + AuthenticationModeBits,
+    IsaPointerBits = 1,
+    IsaPointerMask = ((1 << IsaPointerBits) - 1) << IsaPointerShift,
+    AuthenticatesNullValuesShift = IsaPointerShift + IsaPointerBits,
+    AuthenticatesNullValuesBits = 1,
+    AuthenticatesNullValuesMask = ((1 << AuthenticatesNullValuesBits) - 1)
+                                  << AuthenticatesNullValuesShift,
+    KeyShift = AuthenticatesNullValuesShift + AuthenticatesNullValuesBits,
+    KeyBits = 10,
+    KeyMask = ((1 << KeyBits) - 1) << KeyShift,
+    DiscriminatorShift = KeyShift + KeyBits,
+    DiscriminatorBits = 16,
+    DiscriminatorMask = ((1u << DiscriminatorBits) - 1) << DiscriminatorShift,
+  };
+
+  // bits:     |0      |1      |2..3              |4          |
+  //           |Enabled|Address|AuthenticationMode|ISA pointer|
+  // bits:     |5                |6..15|   16...31   |
+  //           |AuthenticatesNull|Key  |Discriminator|
+  uint32_t Data;
+
+  // The following static assertions check that each of the 32 bits is present
+  // exactly in one of the constants.
+  static_assert((EnabledBits + AddressDiscriminatedBits +
+                 AuthenticationModeBits + IsaPointerBits +
+                 AuthenticatesNullValuesBits + KeyBits + DiscriminatorBits) ==
+                    32,
+                "PointerAuthQualifier should be exactly 32 bits");
+  static_assert((EnabledMask + AddressDiscriminatedMask +
+                 AuthenticationModeMask + IsaPointerMask +
+                 AuthenticatesNullValuesMask + KeyMask + DiscriminatorMask) ==
+                    0xFFFFFFFF,
+                "All masks should cover the entire bits");
+  static_assert((EnabledMask ^ AddressDiscriminatedMask ^
+                 AuthenticationModeMask ^ IsaPointerMask ^
+                 AuthenticatesNullValuesMask ^ KeyMask ^ DiscriminatorMask) ==
+                    0xFFFFFFFF,
+                "All masks should cover the entire bits");
+
+  PointerAuthQualifier(unsigned Key, bool IsAddressDiscriminated,
+                       unsigned ExtraDiscriminator,
+                       PointerAuthenticationMode AuthenticationMode,
+                       bool IsIsaPointer, bool AuthenticatesNullValues)
+      : Data(EnabledMask |
+             (IsAddressDiscriminated
+                  ? llvm::to_underlying(AddressDiscriminatedMask)
+                  : 0) |
+             (Key << KeyShift) |
+             (llvm::to_underlying(AuthenticationMode)
+              << AuthenticationModeShift) |
+             (ExtraDiscriminator << DiscriminatorShift) |
+             (IsIsaPointer << IsaPointerShift) |
+             (AuthenticatesNullValues << AuthenticatesNullValuesShift)) {
+    assert(Key <= KeyNoneInternal);
+    assert(ExtraDiscriminator <= MaxDiscriminator);
+  }
+
+public:
+  enum {
+    KeyNoneInternal = (1u << KeyBits) - 1,
+
+    /// The maximum supported pointer-authentication key.
+    MaxKey = KeyNoneInternal - 1,
+
+    /// The maximum supported pointer-authentication discriminator.
+    MaxDiscriminator = (1u << DiscriminatorBits) - 1
+  };
+
+public:
+  PointerAuthQualifier() : Data(0) {}
----------------
kovdan01 wrote:

Changed to `PointerAuthQualifier() = default;` - we have a user-defined non-default constructor, so, without explicit notice, the default one is deleted (see https://en.cppreference.com/w/cpp/language/default_constructor). See cfb3afe19c698aaf41fb7b492503081989896434


https://github.com/llvm/llvm-project/pull/84384