From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 8 Dec 2011 22:36:35 +0000 (+0000)
Subject: Fix infinite loop in DSE when deleting a free in a reachable loop that's also
X-Git-Tag: android-x86-6.0-r1~255^2~225
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=c9b98ad7a7c3f2c098657a077a995912dce033e3;p=android-x86%2Fexternal-llvm.git

Fix infinite loop in DSE when deleting a free in a reachable loop that's also
trivially infinite.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146197 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index b9b1cc86c29..8729019705f 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -624,6 +624,7 @@ static void FindUnconditionalPreds(SmallVectorImpl<BasicBlock *> &Blocks,
                                    BasicBlock *BB, DominatorTree *DT) {
   for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
     BasicBlock *Pred = *I;
+    if (Pred == BB) continue;
     TerminatorInst *PredTI = Pred->getTerminator();
     if (PredTI->getNumSuccessors() != 1)
       continue;
@@ -853,4 +854,3 @@ void DSE::RemoveAccessedObjects(const AliasAnalysis::Location &LoadedLoc,
        I != E; ++I)
     DeadStackObjects.erase(*I);
 }
-
diff --git a/test/Transforms/DeadStoreElimination/free.ll b/test/Transforms/DeadStoreElimination/free.ll
index 168bd95e539..a5fbdc76387 100644
--- a/test/Transforms/DeadStoreElimination/free.ll
+++ b/test/Transforms/DeadStoreElimination/free.ll
@@ -58,3 +58,13 @@ skipinit1:
   tail call void @free(i8* %alloc1) nounwind
   ret void
 }
+
+; CHECK: @test5
+define void @test5() {
+  br label %bb
+
+bb:
+  tail call void @free(i8* undef) nounwind
+  br label %bb
+}
+