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

[Simon Tatham via llvm-commits]

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@@ -4054,6 +4099,65 @@ static MCRegister MatchRegisterName(StringRef Name);
 
 /// }
 
+static bool isDataTypeToken(StringRef Tok) {
+  static const DenseSet<StringRef> DataTypes{
+      ".8",  ".16",  ".32",  ".64",  ".i8", ".i16", ".i32", ".i64",
+      ".u8", ".u16", ".u32", ".u64", ".s8", ".s16", ".s32", ".s64",
+      ".p8", ".p16", ".f32", ".f64", ".f",  ".d"};
+  return DataTypes.contains(Tok);
+}
+
+static unsigned getMnemonicOpsEndInd(const OperandVector &Operands) {
+  unsigned MnemonicOpsEndInd = 1;
+  // Special case for CPS which has a Mnemonic side token for possibly storing
+  // ie/id variant
+  if (Operands[0]->isToken() &&
+      static_cast<ARMOperand &>(*Operands[0]).getToken() == "cps") {
+    if (Operands.size() > 1 && Operands[1]->isImm() &&
+        static_cast<ARMOperand &>(*Operands[1]).getImm()->getKind() ==
+            llvm::MCExpr::Constant &&
+        (dyn_cast<MCConstantExpr>(
+             static_cast<ARMOperand &>(*Operands[1]).getImm())
+                 ->getValue() == ARM_PROC::IE ||
+         dyn_cast<MCConstantExpr>(
+             static_cast<ARMOperand &>(*Operands[1]).getImm())
+                 ->getValue() == ARM_PROC::ID))
+      ++MnemonicOpsEndInd;
+  }
+
+  // In some circumstances the code code moves to the right
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statham-arm wrote:

I guess "code code" is a braino for "condition code"

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