2 files changed, 18 insertions, 4 deletions

diff --git a/llvm/include/llvm/CodeGen/FastISel.h b/llvm/include/llvm/CodeGen/FastISel.h
index 32d6bb03ec1..c233cd48f44 100644
--- a/llvm/include/llvm/CodeGen/FastISel.h
+++ b/llvm/include/llvm/CodeGen/FastISel.h
@@ -226,6 +226,10 @@ protected:
   /// makes sense (for example, on function calls)
   MachineInstr *EmitStartPt;
 
+  /// Last local value flush point. On a subsequent flush, no local value will
+  /// sink past this point.
+  MachineBasicBlock::iterator LastFlushPoint;
+
 public:
   virtual ~FastISel();
 
@@ -569,7 +573,8 @@ private:
     MachineInstr *FirstTerminator = nullptr;
     unsigned FirstTerminatorOrder = std::numeric_limits<unsigned>::max();
 
-    void initialize(MachineBasicBlock *MBB);
+    void initialize(MachineBasicBlock *MBB,
+                    MachineBasicBlock::iterator LastFlushPoint);
   };
 
   /// Sinks the local value materialization instruction LocalMI to its first use
diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 84196062491..23a7798f867 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -215,6 +215,7 @@ void FastISel::flushLocalValueMap() {
   LastLocalValue = EmitStartPt;
   recomputeInsertPt();
   SavedInsertPt = FuncInfo.InsertPt;
+  LastFlushPoint = FuncInfo.InsertPt;
 }
 
 static bool isRegUsedByPhiNodes(unsigned DefReg,
@@ -228,7 +229,8 @@ static bool isRegUsedByPhiNodes(unsigned DefReg,
 /// Build a map of instruction orders. Return the first terminator and its
 /// order. Consider EH_LABEL instructions to be terminators as well, since local
 /// values for phis after invokes must be materialized before the call.
-void FastISel::InstOrderMap::initialize(MachineBasicBlock *MBB) {
+void FastISel::InstOrderMap::initialize(
+    MachineBasicBlock *MBB, MachineBasicBlock::iterator LastFlushPoint) {
   unsigned Order = 0;
   for (MachineInstr &I : *MBB) {
     if (!FirstTerminator &&
@@ -237,6 +239,10 @@ void FastISel::InstOrderMap::initialize(MachineBasicBlock *MBB) {
       FirstTerminatorOrder = Order;
     }
     Orders[&I] = Order++;
+
+    // We don't need to order instructions past the last flush point.
+    if (I.getIterator() == LastFlushPoint)
+      break;
   }
 }
 
@@ -266,13 +272,16 @@ void FastISel::sinkLocalValueMaterialization(MachineInstr &LocalMI,
   // Number the instructions if we haven't yet so we can efficiently find the
   // earliest use.
   if (OrderMap.Orders.empty())
-    OrderMap.initialize(FuncInfo.MBB);
+    OrderMap.initialize(FuncInfo.MBB, LastFlushPoint);
 
   // Find the first user in the BB.
   MachineInstr *FirstUser = nullptr;
   unsigned FirstOrder = std::numeric_limits<unsigned>::max();
   for (MachineInstr &UseInst : MRI.use_nodbg_instructions(DefReg)) {
-    unsigned UseOrder = OrderMap.Orders[&UseInst];
+    auto I = OrderMap.Orders.find(&UseInst);
+    assert(I != OrderMap.Orders.end() &&
+           "local value used by instruction outside local region");
+    unsigned UseOrder = I->second;
     if (UseOrder < FirstOrder) {
       FirstOrder = UseOrder;
       FirstUser = &UseInst;