1 files changed, 6 insertions, 41 deletions

diff --git a/llvm/lib/Analysis/DemandedBits.cpp b/llvm/lib/Analysis/DemandedBits.cpp
index fcc2fd8962c..0382787fbef 100644
--- a/llvm/lib/Analysis/DemandedBits.cpp
+++ b/llvm/lib/Analysis/DemandedBits.cpp
@@ -314,7 +314,6 @@ void DemandedBits::performAnalysis() {
 
   Visited.clear();
   AliveBits.clear();
-  DeadUses.clear();
 
   SmallVector<Instruction*, 128> Worklist;
 
@@ -375,35 +374,26 @@ void DemandedBits::performAnalysis() {
         Type *T = I->getType();
         if (T->isIntOrIntVectorTy()) {
           unsigned BitWidth = T->getScalarSizeInBits();
-
-          // Previous demanded bits information for this use.
-          APInt ABPrev(BitWidth, 0);
-          auto ABI = AliveBits.find(I);
-          if (ABI != AliveBits.end())
-            ABPrev = ABI->second;
-
           APInt AB = APInt::getAllOnesValue(BitWidth);
           if (UserI->getType()->isIntOrIntVectorTy() && !AOut &&
               !isAlwaysLive(UserI)) {
-            // If all bits of the output are dead, then all bits of the input
-            // are also dead.
             AB = APInt(BitWidth, 0);
           } else {
+            // If all bits of the output are dead, then all bits of the input
             // Bits of each operand that are used to compute alive bits of the
             // output are alive, all others are dead.
             determineLiveOperandBits(UserI, I, OI.getOperandNo(), AOut, AB,
                                      Known, Known2);
-
-            // Keep track of uses which have no demanded bits.
-            if (AB.isNullValue())
-              DeadUses.insert(&OI);
-            else if (ABPrev.isNullValue())
-              DeadUses.erase(&OI);
           }
 
           // If we've added to the set of alive bits (or the operand has not
           // been previously visited), then re-queue the operand to be visited
           // again.
+          APInt ABPrev(BitWidth, 0);
+          auto ABI = AliveBits.find(I);
+          if (ABI != AliveBits.end())
+            ABPrev = ABI->second;
+
           APInt ABNew = AB | ABPrev;
           if (ABNew != ABPrev || ABI == AliveBits.end()) {
             AliveBits[I] = std::move(ABNew);
@@ -436,31 +426,6 @@ bool DemandedBits::isInstructionDead(Instruction *I) {
     !isAlwaysLive(I);
 }
 
-bool DemandedBits::isUseDead(Use *U) {
-  // We only track integer uses, everything else is assumed live.
-  if (!(*U)->getType()->isIntOrIntVectorTy())
-    return false;
-
-  // Uses by always-live instructions are never dead.
-  Instruction *UserI = cast<Instruction>(U->getUser());
-  if (isAlwaysLive(UserI))
-    return false;
-
-  performAnalysis();
-  if (DeadUses.count(U))
-    return true;
-
-  // If no output bits are demanded, no input bits are demanded and the use
-  // is dead. These uses might not be explicitly present in the DeadUses map.
-  if (UserI->getType()->isIntOrIntVectorTy()) {
-    auto Found = AliveBits.find(UserI);
-    if (Found != AliveBits.end() && Found->second.isNullValue())
-      return true;
-  }
-
-  return false;
-}
-
 void DemandedBits::print(raw_ostream &OS) {
   performAnalysis();
   for (auto &KV : AliveBits) {