Revert "[MemorySSA] Revert r293361 and r293363, as the tests fail under asan."

This reverts commit r293471, reapplying r293361 and r293363 with a fix
for an out-of-bounds read.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293474 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 56 insertions, 0 deletions

diff --git a/unittests/Transforms/Utils/MemorySSA.cpp b/unittests/Transforms/Utils/MemorySSA.cpp
index 95ec3ed55e6..0df476bc28c 100644
--- a/unittests/Transforms/Utils/MemorySSA.cpp
+++ b/unittests/Transforms/Utils/MemorySSA.cpp
@@ -365,6 +365,62 @@ TEST_F(MemorySSATest, MoveAStoreUpdaterMove) {
   MSSA.verifyMemorySSA();
 }
 
+TEST_F(MemorySSATest, MoveAStoreAllAround) {
+  // We create a diamond where there is a in the entry, a store on one side, and
+  // a load at the end.  After building MemorySSA, we test updating by moving
+  // the store from the side block to the entry block, then to the other side
+  // block, then to before the load.  This does not destroy the old access.
+  F = Function::Create(
+      FunctionType::get(B.getVoidTy(), {B.getInt8PtrTy()}, false),
+      GlobalValue::ExternalLinkage, "F", &M);
+  BasicBlock *Entry(BasicBlock::Create(C, "", F));
+  BasicBlock *Left(BasicBlock::Create(C, "", F));
+  BasicBlock *Right(BasicBlock::Create(C, "", F));
+  BasicBlock *Merge(BasicBlock::Create(C, "", F));
+  B.SetInsertPoint(Entry);
+  Argument *PointerArg = &*F->arg_begin();
+  StoreInst *EntryStore = B.CreateStore(B.getInt8(16), PointerArg);
+  B.CreateCondBr(B.getTrue(), Left, Right);
+  B.SetInsertPoint(Left);
+  auto *SideStore = B.CreateStore(B.getInt8(16), PointerArg);
+  BranchInst::Create(Merge, Left);
+  BranchInst::Create(Merge, Right);
+  B.SetInsertPoint(Merge);
+  auto *MergeLoad = B.CreateLoad(PointerArg);
+  setupAnalyses();
+  MemorySSA &MSSA = *Analyses->MSSA;
+  MemorySSAUpdater Updater(&MSSA);
+
+  // Move the store
+  auto *EntryStoreAccess = MSSA.getMemoryAccess(EntryStore);
+  auto *SideStoreAccess = MSSA.getMemoryAccess(SideStore);
+  // Before, the load will point to a phi of the EntryStore and SideStore.
+  auto *LoadAccess = cast<MemoryUse>(MSSA.getMemoryAccess(MergeLoad));
+  EXPECT_TRUE(isa<MemoryPhi>(LoadAccess->getDefiningAccess()));
+  MemoryPhi *MergePhi = cast<MemoryPhi>(LoadAccess->getDefiningAccess());
+  EXPECT_EQ(MergePhi->getIncomingValue(1), EntryStoreAccess);
+  EXPECT_EQ(MergePhi->getIncomingValue(0), SideStoreAccess);
+  // Move the store before the entry store
+  SideStore->moveBefore(*EntryStore->getParent(), EntryStore->getIterator());
+  Updater.moveBefore(SideStoreAccess, EntryStoreAccess);
+  // After, it's a phi of the entry store.
+  EXPECT_EQ(MergePhi->getIncomingValue(0), EntryStoreAccess);
+  EXPECT_EQ(MergePhi->getIncomingValue(1), EntryStoreAccess);
+  MSSA.verifyMemorySSA();
+  // Now move the store to the right branch
+  SideStore->moveBefore(*Right, Right->begin());
+  Updater.moveToPlace(SideStoreAccess, Right, MemorySSA::Beginning);
+  MSSA.verifyMemorySSA();
+  EXPECT_EQ(MergePhi->getIncomingValue(0), EntryStoreAccess);
+  EXPECT_EQ(MergePhi->getIncomingValue(1), SideStoreAccess);
+  // Now move it before the load
+  SideStore->moveBefore(MergeLoad);
+  Updater.moveBefore(SideStoreAccess, LoadAccess);
+  EXPECT_EQ(MergePhi->getIncomingValue(0), EntryStoreAccess);
+  EXPECT_EQ(MergePhi->getIncomingValue(1), EntryStoreAccess);
+  MSSA.verifyMemorySSA();
+}
+
 TEST_F(MemorySSATest, RemoveAPhi) {
   // We create a diamond where there is a store on one side, and then a load
   // after the merge point.  This enables us to test a bunch of different