[clang] [Clang][AArch64] Include SME attributes in the name mangling of function types (PR #114209)

[Sander de Smalen via cfe-commits]

================
@@ -3535,6 +3536,70 @@ void CXXNameMangler::mangleExtFunctionInfo(const FunctionType *T) {
   // FIXME: noreturn
 }
 
+enum class AAPCSBitmaskSME : unsigned {
+  ArmStreamingBit = 1 << 0,
+  ArmStreamingCompatibleBit = 1 << 1,
+  ArmAgnosticSMEZAStateBit = 1 << 2,
+  ZA_Shift = 3,
+  ZT0_Shift = 6,
+  NoState = 0b000,
+  ArmIn = 0b001,
+  ArmOut = 0b010,
+  ArmInOut = 0b011,
+  ArmPreserves = 0b100
+};
+
+static unsigned encodeAAPCSZAState(unsigned SMEAttrs) {
+  switch (SMEAttrs) {
+  case FunctionType::ARM_None:
+    return static_cast<unsigned>(AAPCSBitmaskSME::NoState);
----------------
sdesmalen-arm wrote:

You can remove the `static_cast` if you use BitmaskEnum, see `LLVM_MARK_AS_BITMASK_ENUM` or  `LLVM_DECLARE_ENUM_AS_BITMASK`.

Unfortunately I found that `operator<<` is not supported (needed below in mangleSMEAttrs), so I've created #118007.

https://github.com/llvm/llvm-project/pull/114209