Don't use potentially invalidated iterator

If the lhs is evaluated before the rhs, FuncletI's operator-> can trigger the

  assert(isHandleInSync() && "invalid iterator access!");

at include/llvm/ADT/DenseMap.h:1061.  (Happens e.g. when compiled with GCC 6.)

Differential Revision: http://reviews.llvm.org/D18440


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265024 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/BranchFolding.cpp

@@ -453,8 +453,10 @@ MachineBasicBlock *BranchFolder::SplitMBBAt(MachineBasicBlock &CurMBB,
 
   // Add the new block to the funclet.
   const auto &FuncletI = FuncletMembership.find(&CurMBB);
-  if (FuncletI != FuncletMembership.end())
-    FuncletMembership[NewMBB] = FuncletI->second;
+  if (FuncletI != FuncletMembership.end()) {
+    auto n = FuncletI->second;
+    FuncletMembership[NewMBB] = n;
+  }
 
   return NewMBB;
 }