[llvm] [CodeGen][NPM] Port VirtRegRewriter to NPM (PR #130564)

[Pierre van Houtryve via llvm-commits]

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@@ -223,9 +223,21 @@ class VirtRegRewriter : public MachineFunctionPass {
 
 public:
   static char ID;
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Pierre-vh wrote:

unused ID here causes a build failure

https://github.com/llvm/llvm-project/pull/130564