[clang] [Clang][AArch64] Fix checkArmStreamingBuiltin for 'sve-b16b16' (PR #109420)

[Paul Walker via cfe-commits]

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@@ -953,9 +953,20 @@ Intrinsic::Intrinsic(StringRef Name, StringRef Proto, uint64_t MergeTy,
                      SVEEmitter &Emitter, StringRef SVEGuard,
                      StringRef SMEGuard)
     : Name(Name.str()), LLVMName(LLVMName), Proto(Proto.str()),
-      BaseTypeSpec(BT), Class(Class), SVEGuard(SVEGuard.str()),
-      SMEGuard(SMEGuard.str()), MergeSuffix(MergeSuffix.str()),
+      BaseTypeSpec(BT), Class(Class), MergeSuffix(MergeSuffix.str()),
       BaseType(BT, 'd'), Flags(Flags), ImmChecks(Checks) {
+
+  auto FormatGuard = [](StringRef Guard, StringRef Base) -> std::string {
+    if (Guard.empty() || Guard == Base || Guard.starts_with(Base.str() + ","))
+      return Guard.str();
+    if (Guard.contains('|'))
+      return Base.str() + ",(" + Guard.str() + ")";
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paulwalker-arm wrote:

Would it be safer if this check was first? Or more specifically before the `Guard.starts_with...` test?  Consider `sve,sve-optional|sve2`.

https://github.com/llvm/llvm-project/pull/109420