[clang] [NFC][ARM][AArch64] Deduplicated code. (PR #82785)

[Tomas Matheson via cfe-commits]

================
@@ -1369,13 +1369,20 @@ class TargetInfo : public TransferrableTargetInfo,
   }
 
   struct BranchProtectionInfo {
-    LangOptions::SignReturnAddressScopeKind SignReturnAddr =
-        LangOptions::SignReturnAddressScopeKind::None;
-    LangOptions::SignReturnAddressKeyKind SignKey =
-        LangOptions::SignReturnAddressKeyKind::AKey;
-    bool BranchTargetEnforcement = false;
-    bool BranchProtectionPAuthLR = false;
-    bool GuardedControlStack = false;
+    LangOptions::SignReturnAddressScopeKind SignReturnAddr;
+    LangOptions::SignReturnAddressKeyKind SignKey;
+    bool BranchTargetEnforcement;
+    bool BranchProtectionPAuthLR;
+    bool GuardedControlStack;
+
+    BranchProtectionInfo() = default;
+
+    const char *getSignReturnAddrStr() const {
+      static const char *SignReturnAddrStr[] = {"none", "non-leaf", "all"};
+      assert(static_cast<unsigned>(SignReturnAddr) <= 2 &&
+             "Unexpected SignReturnAddressScopeKind");
+      return SignReturnAddrStr[static_cast<int>(SignReturnAddr)];
+    }
----------------
tmatheson-arm wrote:

```suggestion
    const char *getSignReturnAddrStr() const {
    switch (SignReturnAddr) {
      case None:
        return "none";
      case NonLeaf:
        return "non-leaf";
      case All:
        return "all";
      }
      assert(false && "Unexpected SignReturnAddressScopeKind");
    }
```

https://github.com/llvm/llvm-project/pull/82785