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

[Sander de Smalen via cfe-commits]

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@@ -3535,6 +3536,74 @@ void CXXNameMangler::mangleExtFunctionInfo(const FunctionType *T) {
   // FIXME: noreturn
 }
 
+enum SMEState {
+  Normal = 0,
+  SM_Enabled = 1 << 0,
+  SM_Compatible = 1 << 1,
+  ZA_Agnostic = 1 << 2,
+  ZA_Shift = 3,
+  ZT0_Shift = 6,
+  None = 0b000,
+  In = 0b001,
+  Out = 0b010,
+  InOut = 0b011,
+  Preserves = 0b100
+};
+
+unsigned encodeZAState(unsigned SMEAttrs) {
+  switch (SMEAttrs) {
+  case FunctionType::ARM_None:
+    return SMEState::None;
+  case FunctionType::ARM_In:
+    return SMEState::In;
+  case FunctionType::ARM_Out:
+    return SMEState::Out;
+  case FunctionType::ARM_InOut:
+    return SMEState::InOut;
+  case FunctionType::ARM_Preserves:
+    return SMEState::Preserves;
+  }
+  llvm_unreachable("Unrecognised SME attribute");
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sdesmalen-arm wrote:

This is missing a `default` (would otherwise result in warning diagnostic), you could move the `llvm_unreachable` under the `default` case.

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