[lldb] [llvm] [AArch64][llvm] Tighten SYSP parsing; don't disassemble invalid encodings (PR #182410)

[via llvm-commits]

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@@ -3310,35 +3299,47 @@ ParseStatus AArch64AsmParser::tryParsePSBHint(OperandVector &Operands) {
   return ParseStatus::Success;
 }
 
-ParseStatus AArch64AsmParser::tryParseSyspXzrPair(OperandVector &Operands) {
+ParseStatus AArch64AsmParser::tryParseSyspPair(OperandVector &Operands) {
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Lukacma wrote:

beside this function being wrong as mentioned in previous comments, I think the error handling could be vastly improved here. This function does almost the same thing as tryParseGPRSeqPair, just with more pairs, and it reports way better error messages than this one. Since you are rewriting the whole function anyway, maybe it would good idea to improve the errors here as well. It also treats the whole pair as an operand instead of just using single register, which seems more correct. 

https://github.com/llvm/llvm-project/pull/182410