Fix dereferencing end iterator in SimplifyCFG. Patch by Ye Mei.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187646 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 427688fc8e1bfa8f9a85466ff815f0d1c795b52e..d48213ff6e302a16a93bd7ad7740cc5af9aedb92 100644 (file)
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4290,7 +4290,8 @@ bool SimplifyCFGOpt::SimplifyParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
   // Do the transformation.
   BasicBlock *CB;
   bool Iteration = true;
-  BasicBlock::iterator ItOld = Builder.GetInsertPoint();
+  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
   BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
   Value *PC = PBI->getCondition();
   do {
@@ -4319,8 +4320,8 @@ bool SimplifyCFGOpt::SimplifyParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
     // make CB unreachable and let downstream to delete the block.
     new UnreachableInst(CB->getContext(), CB);
   } while (Iteration);
-    
-  Builder.SetInsertPoint(ItOld);
+  if (SaveInsertBB)
+    Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
   DEBUG(dbgs() << "Use parallel and/or in:\n" << *FirstCondBlock);
   return true;
 }
@@ -4454,11 +4455,13 @@ bool SimplifyCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder,
   FirstEntryBlock->getInstList().splice(FirstEntryBlock->end(), SecondEntryBlock->getInstList());
   BranchInst *PBI = dyn_cast<BranchInst>(FirstEntryBlock->getTerminator());
   Value *CC = PBI->getCondition();
-  BasicBlock::iterator ItOld = Builder.GetInsertPoint();
+  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
   Builder.SetInsertPoint(PBI);
   Value *NC = Builder.CreateOr(CInst1, CC);
   PBI->replaceUsesOfWith(CC, NC);
-  Builder.SetInsertPoint(ItOld);
+  if (SaveInsertBB)
+    Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
 
   // Remove IfTrue1
   if (IfTrue1 != FirstEntryBlock) {