1 files changed, 25 insertions, 50 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index d0caf3938a8..3c8f2e9f612 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2176,24 +2176,31 @@ void SelectionDAGBuilder::visitJumpTableHeader(JumpTable &JT,
                                     JumpTableReg, SwitchOp);
   JT.Reg = JumpTableReg;
 
-  // Emit the range check for the jump table, and branch to the default block
-  // for the switch statement if the value being switched on exceeds the largest
-  // case in the switch.
-  SDValue CMP = DAG.getSetCC(
-      dl, TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(),
-                                 Sub.getValueType()),
-      Sub, DAG.getConstant(JTH.Last - JTH.First, dl, VT), ISD::SETUGT);
-
-  SDValue BrCond = DAG.getNode(ISD::BRCOND, dl,
-                               MVT::Other, CopyTo, CMP,
-                               DAG.getBasicBlock(JT.Default));
-
-  // Avoid emitting unnecessary branches to the next block.
-  if (JT.MBB != NextBlock(SwitchBB))
-    BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, BrCond,
-                         DAG.getBasicBlock(JT.MBB));
-
-  DAG.setRoot(BrCond);
+  if (!JTH.OmitRangeCheck) {
+    // Emit the range check for the jump table, and branch to the default block
+    // for the switch statement if the value being switched on exceeds the
+    // largest case in the switch.
+    SDValue CMP = DAG.getSetCC(
+        dl, TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(),
+                                   Sub.getValueType()),
+        Sub, DAG.getConstant(JTH.Last - JTH.First, dl, VT), ISD::SETUGT);
+
+    SDValue BrCond = DAG.getNode(ISD::BRCOND, dl,
+                                 MVT::Other, CopyTo, CMP,
+                                 DAG.getBasicBlock(JT.Default));
+
+    // Avoid emitting unnecessary branches to the next block.
+    if (JT.MBB != NextBlock(SwitchBB))
+      BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, BrCond,
+                           DAG.getBasicBlock(JT.MBB));
+
+    DAG.setRoot(BrCond);
+  } else {
+    SDValue BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, CopyTo,
+                                 DAG.getBasicBlock(JT.MBB));
+    DAG.setRoot(BrCond);
+    SwitchBB->removeSuccessor(JT.Default, true);
+  }
 }
 
 /// Create a LOAD_STACK_GUARD node, and let it carry the target specific global
@@ -10308,38 +10315,6 @@ void SelectionDAGBuilder::visitSwitch(const SwitchInst &SI) {
   // if there are many clusters.
   sortAndRangeify(Clusters);
 
-  if (TM.getOptLevel() != CodeGenOpt::None) {
-    // Replace an unreachable default with the most popular destination.
-    // FIXME: Exploit unreachable default more aggressively.
-    bool UnreachableDefault =
-        isa<UnreachableInst>(SI.getDefaultDest()->getFirstNonPHIOrDbg());
-    if (UnreachableDefault && !Clusters.empty()) {
-      DenseMap<const BasicBlock *, unsigned> Popularity;
-      unsigned MaxPop = 0;
-      const BasicBlock *MaxBB = nullptr;
-      for (auto I : SI.cases()) {
-        const BasicBlock *BB = I.getCaseSuccessor();
-        if (++Popularity[BB] > MaxPop) {
-          MaxPop = Popularity[BB];
-          MaxBB = BB;
-        }
-      }
-      // Set new default.
-      assert(MaxPop > 0 && MaxBB);
-      DefaultMBB = FuncInfo.MBBMap[MaxBB];
-
-      // Remove cases that were pointing to the destination that is now the
-      // default.
-      CaseClusterVector New;
-      New.reserve(Clusters.size());
-      for (CaseCluster &CC : Clusters) {
-        if (CC.MBB != DefaultMBB)
-          New.push_back(CC);
-      }
-      Clusters = std::move(New);
-    }
-  }
-
   // The branch probablity of the peeled case.
   BranchProbability PeeledCaseProb = BranchProbability::getZero();
   MachineBasicBlock *PeeledSwitchMBB =