1 files changed, 29 insertions, 4 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 7bae5048fc0e..d17dd1c5eccb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1691,9 +1691,9 @@ static bool MIIsInTerminatorSequence(const MachineInstr &MI) {
 /// terminator, but additionally the copies that move the vregs into the
 /// physical registers.
 static MachineBasicBlock::iterator
-FindSplitPointForStackProtector(MachineBasicBlock *BB) {
+FindSplitPointForStackProtector(MachineBasicBlock *BB,
+                                const TargetInstrInfo &TII) {
   MachineBasicBlock::iterator SplitPoint = BB->getFirstTerminator();
-  //
   if (SplitPoint == BB->begin())
     return SplitPoint;
 
@@ -1701,6 +1701,31 @@ FindSplitPointForStackProtector(MachineBasicBlock *BB) {
   MachineBasicBlock::iterator Previous = SplitPoint;
   --Previous;
 
+  if (TII.isTailCall(*SplitPoint) &&
+      Previous->getOpcode() == TII.getCallFrameDestroyOpcode()) {
+    // call itself, then we must insert before the sequence even starts. For
+    // example:
+    //     <split point>
+    //     ADJCALLSTACKDOWN ...
+    //     <Moves>
+    //     ADJCALLSTACKUP ...
+    //     TAILJMP somewhere
+    // On the other hand, it could be an unrelated call in which case this tail call
+    // has to register moves of its own and should be the split point. For example:
+    //     ADJCALLSTACKDOWN
+    //     CALL something_else
+    //     ADJCALLSTACKUP
+    //     <split point>
+    //     TAILJMP somewhere
+    do {
+      --Previous;
+      if (Previous->isCall())
+        return SplitPoint;
+    } while(Previous->getOpcode() != TII.getCallFrameSetupOpcode());
+
+    return Previous;
+  }
+
   while (MIIsInTerminatorSequence(*Previous)) {
     SplitPoint = Previous;
     if (Previous == Start)
@@ -1740,7 +1765,7 @@ SelectionDAGISel::FinishBasicBlock() {
     // Add load and check to the basicblock.
     FuncInfo->MBB = ParentMBB;
     FuncInfo->InsertPt =
-        FindSplitPointForStackProtector(ParentMBB);
+        FindSplitPointForStackProtector(ParentMBB, *TII);
     SDB->visitSPDescriptorParent(SDB->SPDescriptor, ParentMBB);
     CurDAG->setRoot(SDB->getRoot());
     SDB->clear();
@@ -1759,7 +1784,7 @@ SelectionDAGISel::FinishBasicBlock() {
     // register allocation issues caused by us splitting the parent mbb. The
     // register allocator will clean up said virtual copies later on.
     MachineBasicBlock::iterator SplitPoint =
-        FindSplitPointForStackProtector(ParentMBB);
+        FindSplitPointForStackProtector(ParentMBB, *TII);
 
     // Splice the terminator of ParentMBB into SuccessMBB.
     SuccessMBB->splice(SuccessMBB->end(), ParentMBB,