[llvm] [NFC][DebugInfo] Deprecate iterator-taking moveBefore and getFirstNonPHI (PR #124290)

[Simon Pilgrim via llvm-commits]

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@@ -280,14 +280,27 @@ class BasicBlock final : public Value, // Basic blocks are data objects also
   /// When adding instructions to the beginning of the basic block, they should
   /// be added before the returned value, not before the first instruction,
   /// which might be PHI. Returns 0 is there's no non-PHI instruction.
-  const Instruction* getFirstNonPHI() const;
-  Instruction* getFirstNonPHI() {
+  ///
+  /// Deprecated in favour of getFirstNonPHIIt, which returns an iterator that
+  /// preserves some debugging information.
+  LLVM_DEPRECATED("Use iterators as instruction positions", "getFirstNonPHIIt")
+  const Instruction *getFirstNonPHI() const;
+  LLVM_DEPRECATED("Use iterators as instruction positions instead",
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RKSimon wrote:

Aren't we only supposed to add LLVM_DEPRECATED once all uses have been removed from trunk as it breaks Werror builds? I've always took LLVM_DEPRECATED as a signal for downstream branches?

https://github.com/llvm/llvm-project/pull/124290