[llvm] [ARM][TableGen][MC] Change the ARM mnemonic operands to be optional for ASM parsing (PR #83436)

[Alfie Richards via llvm-commits]

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@@ -2019,7 +2058,7 @@ emitConvertFuncs(CodeGenTarget &Target, StringRef ClassName,
   CvtOS
       << "                              std::begin(TiedAsmOperandTable)) &&\n";
   CvtOS << "             \"Tied operand not found\");\n";
-  CvtOS << "      unsigned TiedResOpnd = TiedAsmOperandTable[OpIdx][0];\n";
+  CvtOS << "      unsigned TiedResOpnd = TiedAsmOperandTable[*(p + 1)][0];\n";
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AlfieRichardsArm wrote:

It does not, it breaks the tied operands resolution for me, I run into the same issue I had before of the wrong value being used. I think `*(p + 1)` is correct as offsets should not be applied here?

https://github.com/llvm/llvm-project/pull/83436