1 files changed, 11 insertions, 15 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index d3fcba10c275..b7e0e32780b4 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -16,28 +16,21 @@
 #include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/AssumptionCache.h"
-#include "llvm/Analysis/BasicAliasAnalysis.h"
 #include "llvm/Analysis/DependenceAnalysis.h"
 #include "llvm/Analysis/DomTreeUpdater.h"
-#include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopIterator.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/MemorySSA.h"
 #include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
-#include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 using namespace llvm;
 
@@ -261,13 +254,17 @@ private:
     assert(L.getNumBlocks() == LiveLoopBlocks.size() + DeadLoopBlocks.size() &&
            "Malformed block sets?");
 
-    // Now, all exit blocks that are not marked as live are dead.
+    // Now, all exit blocks that are not marked as live are dead, if all their
+    // predecessors are in the loop. This may not be the case, as the input loop
+    // may not by in loop-simplify/canonical form.
     SmallVector<BasicBlock *, 8> ExitBlocks;
     L.getExitBlocks(ExitBlocks);
     SmallPtrSet<BasicBlock *, 8> UniqueDeadExits;
     for (auto *ExitBlock : ExitBlocks)
       if (!LiveExitBlocks.count(ExitBlock) &&
-          UniqueDeadExits.insert(ExitBlock).second)
+          UniqueDeadExits.insert(ExitBlock).second &&
+          all_of(predecessors(ExitBlock),
+                 [this](BasicBlock *Pred) { return L.contains(Pred); }))
         DeadExitBlocks.push_back(ExitBlock);
 
     // Whether or not the edge From->To will still be present in graph after the
@@ -374,7 +371,7 @@ private:
         DeadInstructions.emplace_back(LandingPad);
 
       for (Instruction *I : DeadInstructions) {
-        I->replaceAllUsesWith(UndefValue::get(I->getType()));
+        I->replaceAllUsesWith(PoisonValue::get(I->getType()));
         I->eraseFromParent();
       }
 
@@ -704,8 +701,7 @@ PreservedAnalyses LoopSimplifyCFGPass::run(Loop &L, LoopAnalysisManager &AM,
     MSSAU = MemorySSAUpdater(AR.MSSA);
   bool DeleteCurrentLoop = false;
   if (!simplifyLoopCFG(L, AR.DT, AR.LI, AR.SE,
-                       MSSAU.hasValue() ? MSSAU.getPointer() : nullptr,
-                       DeleteCurrentLoop))
+                       MSSAU ? MSSAU.getPointer() : nullptr, DeleteCurrentLoop))
     return PreservedAnalyses::all();
 
   if (DeleteCurrentLoop)
@@ -739,9 +735,9 @@ public:
     if (MSSAA && VerifyMemorySSA)
       MSSAU->getMemorySSA()->verifyMemorySSA();
     bool DeleteCurrentLoop = false;
-    bool Changed = simplifyLoopCFG(
-        *L, DT, LI, SE, MSSAU.hasValue() ? MSSAU.getPointer() : nullptr,
-        DeleteCurrentLoop);
+    bool Changed =
+        simplifyLoopCFG(*L, DT, LI, SE, MSSAU ? MSSAU.getPointer() : nullptr,
+                        DeleteCurrentLoop);
     if (DeleteCurrentLoop)
       LPM.markLoopAsDeleted(*L);
     return Changed;