[clang] [llvm] [LLVM] Add InsertPosition union-type to remove overloads of Instruction-creation (PR #94226)

[Nikita Popov via cfe-commits]

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@@ -44,6 +44,23 @@ template <> struct ilist_alloc_traits<Instruction> {
 iterator_range<simple_ilist<DbgRecord>::iterator>
 getDbgRecordRange(DbgMarker *);
 
+class InsertPosition {
+  using InstListType = SymbolTableList<Instruction, ilist_iterator_bits<true>,
+                                       ilist_parent<BasicBlock>>;
+  InstListType::iterator InsertAt;
+
+public:
+  InsertPosition(std::nullopt_t) : InsertAt() {}
+  InsertPosition(std::nullptr_t) : InsertAt() {}
+  // LLVM_DEPRECATED("Use BasicBlock::iterators for insertion instead",
+  // "BasicBlock::iterator")
+  InsertPosition(Instruction *InsertBefore);
+  InsertPosition(BasicBlock *InsertAtEnd);
+  InsertPosition(InstListType::iterator InsertAt) : InsertAt(InsertAt) {}
+  operator InstListType::iterator() const { return InsertAt; }
+  bool IsValid() const { return InsertAt.getNodePtr(); }
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nikic wrote:

I think you added an isValid() method to the iterator itself?

https://github.com/llvm/llvm-project/pull/94226