Added helper function removeHint in VISCUtils.h

llvm/include/llvm/SupportVISC/VISCUtils.h

@@ -486,6 +486,62 @@ void addHint(Function* F, visc::Target T) {
   HintNode->addOperand(N);
 }
 
+// This function removes the hint as metadata in visc code
+void removeHint(Function* F, visc::Target T) {
+  // Get Module
+  Module* M = F->getParent();
+  DEBUG(errs() << "Remove preferred target for " << F->getName() << ": " << T << "\n");
+
+  // Based on the hint, get the hint metadata
+  NamedMDNode* HintNode;
+  switch (T) {
+    case visc::GPU_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_gpu");
+      break;
+    case visc::SPIR_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_spir");
+      break;
+    case visc::CUDNN_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_cudnn");
+      break;
+    case visc::PROMISE_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_promise");
+      break;
+    case visc::CPU_OR_GPU_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_cpu_gpu");
+      break;
+    case visc::CPU_OR_SPIR_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_cpu_spir");
+      break;
+    case visc::CPU_TARGET:
+      HintNode = M->getOrInsertNamedMetadata("visc_hint_cpu");
+      break;
+    default:
+      llvm_unreachable("Unsupported Target Hint!");
+      break;
+  }
+
+  // Gather metadata nodes, and keep those not associated with this function
+  MDNode* N = MDNode::get(M->getContext(),
+                          ArrayRef<Metadata*>(ValueAsMetadata::get(F)));
+  std::vector<MDNode*> MDNodes;
+
+  for (unsigned i = 0; i < HintNode->getNumOperands(); i++) {
+    MDNode* MDN = HintNode->getOperand(i);
+    if (MDN == N) {
+      continue;
+    }
+    MDNodes.push_back(MDN);
+  }
+
+  HintNode->dropAllReferences();
+
+  for (unsigned i = 0; i < MDNodes.size(); i++) {
+    HintNode->addOperand(MDNodes[i]);
+  }
+
+}
+
 visc::Target getPreferredTarget(Function* F) {
   DEBUG(errs() << "Finding preferred target for " << F->getName() << "\n");
   Module* M = F->getParent();