1 files changed, 45 insertions, 0 deletions
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index beb3989..8cd58975 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -141,6 +141,51 @@ bool Value::hasNUsesOrMore(unsigned N) const {
   return hasNItemsOrMore(use_begin(), use_end(), N);
 }
 
+static bool isUnDroppableUser(const User *U) { return !U->isDroppable(); }
+
+Use *Value::getSingleUndroppableUse() {
+  Use *Result = nullptr;
+  for (Use &U : uses()) {
+    if (!U.getUser()->isDroppable()) {
+      if (Result)
+        return nullptr;
+      Result = &U;
+    }
+  }
+  return Result;
+}
+
+bool Value::hasNUndroppableUses(unsigned int N) const {
+  return hasNItems(user_begin(), user_end(), N, isUnDroppableUser);
+}
+
+bool Value::hasNUndroppableUsesOrMore(unsigned int N) const {
+  return hasNItemsOrMore(user_begin(), user_end(), N, isUnDroppableUser);
+}
+
+void Value::dropDroppableUses(
+    llvm::function_ref<bool(const Use *)> ShouldDrop) {
+  SmallVector<Use *, 8> ToBeEdited;
+  for (Use &U : uses())
+    if (U.getUser()->isDroppable() && ShouldDrop(&U))
+      ToBeEdited.push_back(&U);
+  for (Use *U : ToBeEdited) {
+    U->removeFromList();
+    if (auto *Assume = dyn_cast<IntrinsicInst>(U->getUser())) {
+      assert(Assume->getIntrinsicID() == Intrinsic::assume);
+      unsigned OpNo = U->getOperandNo();
+      if (OpNo == 0)
+        Assume->setOperand(0, ConstantInt::getTrue(Assume->getContext()));
+      else {
+        Assume->setOperand(OpNo, UndefValue::get(U->get()->getType()));
+        CallInst::BundleOpInfo &BOI = Assume->getBundleOpInfoForOperand(OpNo);
+        BOI.Tag = getContext().pImpl->getOrInsertBundleTag("ignore");
+      }
+    } else
+      llvm_unreachable("unkown droppable use");
+  }
+}
+
 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
   // This can be computed either by scanning the instructions in BB, or by
   // scanning the use list of this Value. Both lists can be very long, but