[llvm] [MachineInstr] add insert method for variadic instructions (PR #67699)

[Matthias Braun via llvm-commits]

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@@ -1818,6 +1818,9 @@ class MachineInstr
   /// preferred.
   void addOperand(const MachineOperand &Op);
 
+  /// Inserts Ops BEFORE It. Can untie/retie tied operands.
+  void insert(mop_iterator It, ArrayRef<MachineOperand> Ops);
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MatzeB wrote:

Another compiler I worked on would always call these sort of parameters `InsertBefore` or `InsertAfter` (instead of `It` here) to make the semantics clear. Maybe that would be neat here to show the semantics? On the other hand I haven't seen this pattern anywhere else in LLVM so no strong opinion.

https://github.com/llvm/llvm-project/pull/67699