[MemorySSA] Use SetVector to avoid nondeterminism.

Summary:
Use a SetVector for DeadBlockSet.
Resolves PR42574.

Reviewers: george.burgess.iv, uabelho, dblaikie

Subscribers: jlebar, Prazek, mgrang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64601

llvm-svn: 365970

2 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 91d33cb0f20..39b6b889f91 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -2238,7 +2238,7 @@ bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI,
   assert(Reachable.size() < F.size());
   NumRemoved += F.size()-Reachable.size();
 
-  SmallPtrSet<BasicBlock *, 16> DeadBlockSet;
+  SmallSetVector<BasicBlock *, 8> DeadBlockSet;
   for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ++I) {
     auto *BB = &*I;
     if (Reachable.count(BB))
diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index 5ec12aafff0..7e6da02d570 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -681,7 +681,8 @@ ReprocessLoop:
       }
       DT->eraseNode(ExitingBlock);
       if (MSSAU) {
-        SmallPtrSet<BasicBlock *, 1> ExitBlockSet{ExitingBlock};
+        SmallSetVector<BasicBlock *, 8> ExitBlockSet;
+        ExitBlockSet.insert(ExitingBlock);
         MSSAU->removeBlocks(ExitBlockSet);
       }