[llvm] [SandboxIR][Region] Implement an auxiliary vector in Region (PR #126376)

[Jorge Gorbe Moya via llvm-commits]

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@@ -93,16 +135,34 @@ Region::createRegionsFromMD(Function &F, TargetTransformInfo &TTI) {
   auto &Ctx = F.getContext();
   for (BasicBlock &BB : F) {
     for (Instruction &Inst : BB) {
-      if (auto *MDN = cast<llvm::Instruction>(Inst.Val)->getMetadata(MDKind)) {
+      auto *LLVMI = cast<llvm::Instruction>(Inst.Val);
+      if (auto *MDN = LLVMI->getMetadata(MDKind)) {
+        Region *R = nullptr;
         auto [It, Inserted] = MDNToRegion.try_emplace(MDN);
         if (Inserted) {
           Regions.push_back(std::make_unique<Region>(Ctx, TTI));
-          It->second = Regions.back().get();
+          R = Regions.back().get();
+          It->second = R;
+        } else {
+          R = It->second;
+        }
+        R->add(&Inst);
+
+        if (auto *AuxMDN = LLVMI->getMetadata(AuxMDKind)) {
+          llvm::Constant *IdxC =
+              dyn_cast<ConstantAsMetadata>(AuxMDN->getOperand(0))->getValue();
+          auto Idx = cast<llvm::ConstantInt>(IdxC)->getSExtValue();
+          R->setAux(Idx, &Inst);
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slackito wrote:

Here we could have a check that we don't have two different values whose metadata claims the same index in the aux vector.

https://github.com/llvm/llvm-project/pull/126376