Enable support of VecLoad/VecStore in LSE

Changes:
- Enable VecLoad and VecStore support in LSE.
- This CL is based on Mingyao's CL: More general store elimination.
- The new gtest load_store_elimination_test is to test some corner cases
  where ArrayGet/ArraySet/VecLoad/VecStore are mixed and overlap.
- The new java 530-checker-lse-simd.

Test: test.py --host --optimizing --jit --gtest
Test: test.py --target --optimizing --jit
Test: run-gtests.sh
Test: load_store_elimination_test
Test: 530-checker-lse-simd
Test: ./art/test/run-test --optimizing --64 --gcstress 667-checker-simd-alignment
Test: m -j80 art-check-testing-apex-gen

Change-Id: I2d2024ec75a2aaef56b527db98abb40c5f16be79
diff --git a/compiler/optimizing/load_store_elimination_test.cc b/compiler/optimizing/load_store_elimination_test.cc
new file mode 100644
index 0000000..7380378
--- /dev/null
+++ b/compiler/optimizing/load_store_elimination_test.cc
@@ -0,0 +1,893 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <tuple>
+
+#include "load_store_analysis.h"
+#include "load_store_elimination.h"
+#include "nodes.h"
+#include "optimizing_unit_test.h"
+#include "side_effects_analysis.h"
+
+#include "gtest/gtest.h"
+
+namespace art {
+
+class LoadStoreEliminationTest : public ImprovedOptimizingUnitTest {
+ public:
+  void PerformLSE() {
+    graph_->BuildDominatorTree();
+    SideEffectsAnalysis side_effects(graph_);
+    side_effects.Run();
+    LoadStoreAnalysis lsa(graph_);
+    lsa.Run();
+    LoadStoreElimination lse(graph_, side_effects, lsa, nullptr);
+    lse.Run();
+    EXPECT_TRUE(CheckGraphSkipRefTypeInfoChecks());
+  }
+
+  // Create instructions shared among tests.
+  void CreateEntryBlockInstructions() {
+    HInstruction* c1 = graph_->GetIntConstant(1);
+    HInstruction* c4 = graph_->GetIntConstant(4);
+    i_add1_ = new (GetAllocator()) HAdd(DataType::Type::kInt32, i_, c1);
+    i_add4_ = new (GetAllocator()) HAdd(DataType::Type::kInt32, i_, c4);
+    entry_block_->AddInstruction(i_add1_);
+    entry_block_->AddInstruction(i_add4_);
+    entry_block_->AddInstruction(new (GetAllocator()) HGoto());
+  }
+
+  // Create the major CFG used by tests:
+  //    entry
+  //      |
+  //  pre_header
+  //      |
+  //    loop[]
+  //      |
+  //   return
+  //      |
+  //     exit
+  void CreateTestControlFlowGraph() {
+    pre_header_ = new (GetAllocator()) HBasicBlock(graph_);
+    loop_ = new (GetAllocator()) HBasicBlock(graph_);
+
+    graph_->AddBlock(pre_header_);
+    graph_->AddBlock(loop_);
+
+    entry_block_->ReplaceSuccessor(return_block_, pre_header_);
+    pre_header_->AddSuccessor(loop_);
+    loop_->AddSuccessor(loop_);
+    loop_->AddSuccessor(return_block_);
+
+    HInstruction* c0 = graph_->GetIntConstant(0);
+    HInstruction* c1 = graph_->GetIntConstant(1);
+    HInstruction* c128 = graph_->GetIntConstant(128);
+
+    CreateEntryBlockInstructions();
+
+    // pre_header block
+    //   phi = 0;
+    phi_ = new (GetAllocator()) HPhi(GetAllocator(), 0, 0, DataType::Type::kInt32);
+    loop_->AddPhi(phi_);
+    pre_header_->AddInstruction(new (GetAllocator()) HGoto());
+    phi_->AddInput(c0);
+
+    // loop block:
+    //   suspend_check
+    //   phi++;
+    //   if (phi >= 128)
+    suspend_check_ = new (GetAllocator()) HSuspendCheck();
+    HInstruction* inc_phi = new (GetAllocator()) HAdd(DataType::Type::kInt32, phi_, c1);
+    HInstruction* cmp = new (GetAllocator()) HGreaterThanOrEqual(phi_, c128);
+    HInstruction* hif = new (GetAllocator()) HIf(cmp);
+    loop_->AddInstruction(suspend_check_);
+    loop_->AddInstruction(inc_phi);
+    loop_->AddInstruction(cmp);
+    loop_->AddInstruction(hif);
+    phi_->AddInput(inc_phi);
+
+    CreateEnvForSuspendCheck();
+  }
+
+  void CreateEnvForSuspendCheck() {
+    ArenaVector<HInstruction*> current_locals({array_, i_, j_},
+                                              GetAllocator()->Adapter(kArenaAllocInstruction));
+    ManuallyBuildEnvFor(suspend_check_, &current_locals);
+  }
+
+  // Create the diamond-shaped CFG:
+  //      upper
+  //      /   \
+  //    left  right
+  //      \   /
+  //      down
+  //
+  // Return: the basic blocks forming the CFG in the following order {upper, left, right, down}.
+  std::tuple<HBasicBlock*, HBasicBlock*, HBasicBlock*, HBasicBlock*> CreateDiamondShapedCFG() {
+    CreateEntryBlockInstructions();
+
+    HBasicBlock* upper = new (GetAllocator()) HBasicBlock(graph_);
+    HBasicBlock* left = new (GetAllocator()) HBasicBlock(graph_);
+    HBasicBlock* right = new (GetAllocator()) HBasicBlock(graph_);
+
+    graph_->AddBlock(upper);
+    graph_->AddBlock(left);
+    graph_->AddBlock(right);
+
+    entry_block_->ReplaceSuccessor(return_block_, upper);
+    upper->AddSuccessor(left);
+    upper->AddSuccessor(right);
+    left->AddSuccessor(return_block_);
+    right->AddSuccessor(return_block_);
+
+    HInstruction* cmp = new (GetAllocator()) HGreaterThanOrEqual(i_, j_);
+    HInstruction* hif = new (GetAllocator()) HIf(cmp);
+    upper->AddInstruction(cmp);
+    upper->AddInstruction(hif);
+
+    left->AddInstruction(new (GetAllocator()) HGoto());
+    right->AddInstruction(new (GetAllocator()) HGoto());
+
+    return std::make_tuple(upper, left, right, return_block_);
+  }
+
+  // Add a HVecLoad instruction to the end of the provided basic block.
+  //
+  // Return: the created HVecLoad instruction.
+  HInstruction* AddVecLoad(HBasicBlock* block, HInstruction* array, HInstruction* index) {
+    DCHECK(block != nullptr);
+    DCHECK(array != nullptr);
+    DCHECK(index != nullptr);
+    HInstruction* vload = new (GetAllocator()) HVecLoad(
+        GetAllocator(),
+        array,
+        index,
+        DataType::Type::kInt32,
+        SideEffects::ArrayReadOfType(DataType::Type::kInt32),
+        4,
+        /*is_string_char_at*/ false,
+        kNoDexPc);
+    block->InsertInstructionBefore(vload, block->GetLastInstruction());
+    return vload;
+  }
+
+  // Add a HVecStore instruction to the end of the provided basic block.
+  // If no vdata is specified, generate HVecStore: array[index] = [1,1,1,1].
+  //
+  // Return: the created HVecStore instruction.
+  HInstruction* AddVecStore(HBasicBlock* block,
+                            HInstruction* array,
+                            HInstruction* index,
+                            HInstruction* vdata = nullptr) {
+    DCHECK(block != nullptr);
+    DCHECK(array != nullptr);
+    DCHECK(index != nullptr);
+    if (vdata == nullptr) {
+      HInstruction* c1 = graph_->GetIntConstant(1);
+      vdata = new (GetAllocator()) HVecReplicateScalar(GetAllocator(),
+                                                       c1,
+                                                       DataType::Type::kInt32,
+                                                       4,
+                                                       kNoDexPc);
+      block->InsertInstructionBefore(vdata, block->GetLastInstruction());
+    }
+    HInstruction* vstore = new (GetAllocator()) HVecStore(
+        GetAllocator(),
+        array,
+        index,
+        vdata,
+        DataType::Type::kInt32,
+        SideEffects::ArrayWriteOfType(DataType::Type::kInt32),
+        4,
+        kNoDexPc);
+    block->InsertInstructionBefore(vstore, block->GetLastInstruction());
+    return vstore;
+  }
+
+  // Add a HArrayGet instruction to the end of the provided basic block.
+  //
+  // Return: the created HArrayGet instruction.
+  HInstruction* AddArrayGet(HBasicBlock* block, HInstruction* array, HInstruction* index) {
+    DCHECK(block != nullptr);
+    DCHECK(array != nullptr);
+    DCHECK(index != nullptr);
+    HInstruction* get = new (GetAllocator()) HArrayGet(array, index, DataType::Type::kInt32, 0);
+    block->InsertInstructionBefore(get, block->GetLastInstruction());
+    return get;
+  }
+
+  // Add a HArraySet instruction to the end of the provided basic block.
+  // If no data is specified, generate HArraySet: array[index] = 1.
+  //
+  // Return: the created HArraySet instruction.
+  HInstruction* AddArraySet(HBasicBlock* block,
+                            HInstruction* array,
+                            HInstruction* index,
+                            HInstruction* data = nullptr) {
+    DCHECK(block != nullptr);
+    DCHECK(array != nullptr);
+    DCHECK(index != nullptr);
+    if (data == nullptr) {
+      data = graph_->GetIntConstant(1);
+    }
+    HInstruction* store = new (GetAllocator()) HArraySet(array,
+                                                         index,
+                                                         data,
+                                                         DataType::Type::kInt32,
+                                                         0);
+    block->InsertInstructionBefore(store, block->GetLastInstruction());
+    return store;
+  }
+
+  void CreateParameters() override {
+    parameters_.push_back(new (GetAllocator()) HParameterValue(graph_->GetDexFile(),
+                                                               dex::TypeIndex(0),
+                                                               0,
+                                                               DataType::Type::kInt32));
+    array_ = parameters_.back();
+    parameters_.push_back(new (GetAllocator()) HParameterValue(graph_->GetDexFile(),
+                                                               dex::TypeIndex(1),
+                                                               1,
+                                                               DataType::Type::kInt32));
+    i_ = parameters_.back();
+    parameters_.push_back(new (GetAllocator()) HParameterValue(graph_->GetDexFile(),
+                                                               dex::TypeIndex(1),
+                                                               2,
+                                                               DataType::Type::kInt32));
+    j_ = parameters_.back();
+  }
+
+  HBasicBlock* pre_header_;
+  HBasicBlock* loop_;
+
+  HInstruction* array_;
+  HInstruction* i_;
+  HInstruction* j_;
+  HInstruction* i_add1_;
+  HInstruction* i_add4_;
+  HInstruction* suspend_check_;
+
+  HPhi* phi_;
+};
+
+TEST_F(LoadStoreEliminationTest, ArrayGetSetElimination) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c1 = graph_->GetIntConstant(1);
+  HInstruction* c2 = graph_->GetIntConstant(2);
+  HInstruction* c3 = graph_->GetIntConstant(3);
+
+  // array[1] = 1;
+  // x = array[1];  <--- Remove.
+  // y = array[2];
+  // array[1] = 1;  <--- Remove, since it stores same value.
+  // array[i] = 3;  <--- MAY alias.
+  // array[1] = 1;  <--- Cannot remove, even if it stores the same value.
+  AddArraySet(entry_block_, array_, c1, c1);
+  HInstruction* load1 = AddArrayGet(entry_block_, array_, c1);
+  HInstruction* load2 = AddArrayGet(entry_block_, array_, c2);
+  HInstruction* store1 = AddArraySet(entry_block_, array_, c1, c1);
+  AddArraySet(entry_block_, array_, i_, c3);
+  HInstruction* store2 = AddArraySet(entry_block_, array_, c1, c1);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(load1));
+  ASSERT_FALSE(IsRemoved(load2));
+  ASSERT_TRUE(IsRemoved(store1));
+  ASSERT_FALSE(IsRemoved(store2));
+}
+
+TEST_F(LoadStoreEliminationTest, SameHeapValue1) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c1 = graph_->GetIntConstant(1);
+  HInstruction* c2 = graph_->GetIntConstant(2);
+
+  // Test LSE handling same value stores on array.
+  // array[1] = 1;
+  // array[2] = 1;
+  // array[1] = 1;  <--- Can remove.
+  // array[1] = 2;  <--- Can NOT remove.
+  AddArraySet(entry_block_, array_, c1, c1);
+  AddArraySet(entry_block_, array_, c2, c1);
+  HInstruction* store1 = AddArraySet(entry_block_, array_, c1, c1);
+  HInstruction* store2 = AddArraySet(entry_block_, array_, c1, c2);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(store1));
+  ASSERT_FALSE(IsRemoved(store2));
+}
+
+TEST_F(LoadStoreEliminationTest, SameHeapValue2) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  // Test LSE handling same value stores on vector.
+  // vdata = [0x1, 0x2, 0x3, 0x4, ...]
+  // VecStore array[i...] = vdata;
+  // VecStore array[j...] = vdata;  <--- MAY ALIAS.
+  // VecStore array[i...] = vdata;  <--- Cannot Remove, even if it's same value.
+  AddVecStore(entry_block_, array_, i_);
+  AddVecStore(entry_block_, array_, j_);
+  HInstruction* vstore = AddVecStore(entry_block_, array_, i_);
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vstore));
+}
+
+TEST_F(LoadStoreEliminationTest, SameHeapValue3) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  // VecStore array[i...] = vdata;
+  // VecStore array[i+1...] = vdata;  <--- MAY alias due to partial overlap.
+  // VecStore array[i...] = vdata;    <--- Cannot remove, even if it's same value.
+  AddVecStore(entry_block_, array_, i_);
+  AddVecStore(entry_block_, array_, i_add1_);
+  HInstruction* vstore = AddVecStore(entry_block_, array_, i_);
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vstore));
+}
+
+TEST_F(LoadStoreEliminationTest, OverlappingLoadStore) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c1 = graph_->GetIntConstant(1);
+
+  // Test LSE handling array LSE when there is vector store in between.
+  // a[i] = 1;
+  // .. = a[i];                <-- Remove.
+  // a[i,i+1,i+2,i+3] = data;  <-- PARTIAL OVERLAP !
+  // .. = a[i];                <-- Cannot remove.
+  AddArraySet(entry_block_, array_, i_, c1);
+  HInstruction* load1 = AddArrayGet(entry_block_, array_, i_);
+  AddVecStore(entry_block_, array_, i_);
+  HInstruction* load2 = AddArrayGet(entry_block_, array_, i_);
+
+  // Test LSE handling vector load/store partial overlap.
+  // a[i,i+1,i+2,i+3] = data;
+  // a[i+4,i+5,i+6,i+7] = data;
+  // .. = a[i,i+1,i+2,i+3];
+  // .. = a[i+4,i+5,i+6,i+7];
+  // a[i+1,i+2,i+3,i+4] = data;  <-- PARTIAL OVERLAP !
+  // .. = a[i,i+1,i+2,i+3];
+  // .. = a[i+4,i+5,i+6,i+7];
+  AddVecStore(entry_block_, array_, i_);
+  AddVecStore(entry_block_, array_, i_add4_);
+  HInstruction* vload1 = AddVecLoad(entry_block_, array_, i_);
+  HInstruction* vload2 = AddVecLoad(entry_block_, array_, i_add4_);
+  AddVecStore(entry_block_, array_, i_add1_);
+  HInstruction* vload3 = AddVecLoad(entry_block_, array_, i_);
+  HInstruction* vload4 = AddVecLoad(entry_block_, array_, i_add4_);
+
+  // Test LSE handling vector LSE when there is array store in between.
+  // a[i,i+1,i+2,i+3] = data;
+  // a[i+1] = 1;                 <-- PARTIAL OVERLAP !
+  // .. = a[i,i+1,i+2,i+3];
+  AddVecStore(entry_block_, array_, i_);
+  AddArraySet(entry_block_, array_, i_, c1);
+  HInstruction* vload5 = AddVecLoad(entry_block_, array_, i_);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(load1));
+  ASSERT_FALSE(IsRemoved(load2));
+
+  ASSERT_TRUE(IsRemoved(vload1));
+  ASSERT_TRUE(IsRemoved(vload2));
+  ASSERT_FALSE(IsRemoved(vload3));
+  ASSERT_FALSE(IsRemoved(vload4));
+
+  ASSERT_FALSE(IsRemoved(vload5));
+}
+// function (int[] a, int j) {
+// a[j] = 1;
+// for (int i=0; i<128; i++) {
+//    /* doesn't do any write */
+// }
+// a[j] = 1;
+TEST_F(LoadStoreEliminationTest, StoreAfterLoopWithoutSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c1 = graph_->GetIntConstant(1);
+
+  // a[j] = 1
+  AddArraySet(pre_header_, array_, j_, c1);
+
+  // LOOP BODY:
+  // .. = a[i,i+1,i+2,i+3];
+  AddVecLoad(loop_, array_, phi_);
+
+  // a[j] = 1;
+  HInstruction* array_set = AddArraySet(return_block_, array_, j_, c1);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(array_set));
+}
+
+// function (int[] a, int j) {
+//   int[] b = new int[128];
+//   a[j] = 0;
+//   for (int phi=0; phi<128; phi++) {
+//     a[phi,phi+1,phi+2,phi+3] = [1,1,1,1];
+//     b[phi,phi+1,phi+2,phi+3] = a[phi,phi+1,phi+2,phi+3];
+//   }
+//   a[j] = 0;
+// }
+TEST_F(LoadStoreEliminationTest, StoreAfterSIMDLoopWithSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_b = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_b, pre_header_->GetLastInstruction());
+  array_b->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // a[j] = 0;
+  AddArraySet(pre_header_, array_, j_, c0);
+
+  // LOOP BODY:
+  // a[phi,phi+1,phi+2,phi+3] = [1,1,1,1];
+  // b[phi,phi+1,phi+2,phi+3] = a[phi,phi+1,phi+2,phi+3];
+  AddVecStore(loop_, array_, phi_);
+  HInstruction* vload = AddVecLoad(loop_, array_, phi_);
+  AddVecStore(loop_, array_b, phi_, vload->AsVecLoad());
+
+  // a[j] = 0;
+  HInstruction* a_set = AddArraySet(return_block_, array_, j_, c0);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(vload));
+  ASSERT_FALSE(IsRemoved(a_set));  // Cannot remove due to write side-effect in the loop.
+}
+
+// function (int[] a, int j) {
+//   int[] b = new int[128];
+//   a[j] = 0;
+//   for (int phi=0; phi<128; phi++) {
+//     a[phi,phi+1,phi+2,phi+3] = [1,1,1,1];
+//     b[phi,phi+1,phi+2,phi+3] = a[phi,phi+1,phi+2,phi+3];
+//   }
+//   x = a[j];
+// }
+TEST_F(LoadStoreEliminationTest, LoadAfterSIMDLoopWithSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_b = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_b, pre_header_->GetLastInstruction());
+  array_b->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // a[j] = 0;
+  AddArraySet(pre_header_, array_, j_, c0);
+
+  // LOOP BODY:
+  // a[phi,phi+1,phi+2,phi+3] = [1,1,1,1];
+  // b[phi,phi+1,phi+2,phi+3] = a[phi,phi+1,phi+2,phi+3];
+  AddVecStore(loop_, array_, phi_);
+  HInstruction* vload = AddVecLoad(loop_, array_, phi_);
+  AddVecStore(loop_, array_b, phi_, vload->AsVecLoad());
+
+  // x = a[j];
+  HInstruction* load = AddArrayGet(return_block_, array_, j_);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(vload));
+  ASSERT_FALSE(IsRemoved(load));  // Cannot remove due to write side-effect in the loop.
+}
+
+// Check that merging works correctly when there are VecStors in predecessors.
+//
+//                  vstore1: a[i,... i + 3] = [1,...1]
+//                       /          \
+//                      /            \
+// vstore2: a[i,... i + 3] = [1,...1]  vstore3: a[i+1, ... i + 4] = [1, ... 1]
+//                     \              /
+//                      \            /
+//                  vstore4: a[i,... i + 3] = [1,...1]
+//
+// Expected:
+//   'vstore2' is removed.
+//   'vstore3' is not removed.
+//   'vstore4' is not removed. Such cases are not supported at the moment.
+TEST_F(LoadStoreEliminationTest, MergePredecessorVecStores) {
+  InitGraph();
+
+  HBasicBlock* upper;
+  HBasicBlock* left;
+  HBasicBlock* right;
+  HBasicBlock* down;
+  std::tie(upper, left, right, down) = CreateDiamondShapedCFG();
+
+  // upper: a[i,... i + 3] = [1,...1]
+  HInstruction* vstore1 = AddVecStore(upper, array_, i_);
+  HInstruction* vdata = vstore1->InputAt(2);
+
+  // left: a[i,... i + 3] = [1,...1]
+  HInstruction* vstore2 = AddVecStore(left, array_, i_, vdata);
+
+  // right: a[i+1, ... i + 4] = [1, ... 1]
+  HInstruction* vstore3 = AddVecStore(right, array_, i_add1_, vdata);
+
+  // down: a[i,... i + 3] = [1,...1]
+  HInstruction* vstore4 = AddVecStore(down, array_, i_, vdata);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(vstore2));
+  ASSERT_FALSE(IsRemoved(vstore3));
+  ASSERT_FALSE(IsRemoved(vstore4));
+}
+
+// Check that merging works correctly when there are ArraySets in predecessors.
+//
+//          a[i] = 1
+//        /          \
+//       /            \
+// store1: a[i] = 1  store2: a[i+1] = 1
+//       \            /
+//        \          /
+//          store3: a[i] = 1
+//
+// Expected:
+//   'store1' is removed.
+//   'store2' is not removed.
+//   'store3' is removed.
+TEST_F(LoadStoreEliminationTest, MergePredecessorStores) {
+  InitGraph();
+
+  HBasicBlock* upper;
+  HBasicBlock* left;
+  HBasicBlock* right;
+  HBasicBlock* down;
+  std::tie(upper, left, right, down) = CreateDiamondShapedCFG();
+
+  // upper: a[i,... i + 3] = [1,...1]
+  AddArraySet(upper, array_, i_);
+
+  // left: a[i,... i + 3] = [1,...1]
+  HInstruction* store1 = AddArraySet(left, array_, i_);
+
+  // right: a[i+1, ... i + 4] = [1, ... 1]
+  HInstruction* store2 = AddArraySet(right, array_, i_add1_);
+
+  // down: a[i,... i + 3] = [1,...1]
+  HInstruction* store3 = AddArraySet(down, array_, i_);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(store1));
+  ASSERT_FALSE(IsRemoved(store2));
+  ASSERT_TRUE(IsRemoved(store3));
+}
+
+// Check that redundant VStore/VLoad are removed from a SIMD loop.
+//
+//  LOOP BODY
+//     vstore1: a[i,... i + 3] = [1,...1]
+//     vload:   x = a[i,... i + 3]
+//     vstore2: b[i,... i + 3] = x
+//     vstore3: a[i,... i + 3] = [1,...1]
+//
+// Expected:
+//   'vstore1' is not removed.
+//   'vload' is removed.
+//   'vstore3' is removed.
+TEST_F(LoadStoreEliminationTest, RedundantVStoreVLoadInLoop) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  HInstruction* array_b = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_b, pre_header_->GetLastInstruction());
+  array_b->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // LOOP BODY:
+  //    a[i,... i + 3] = [1,...1]
+  //    x = a[i,... i + 3]
+  //    b[i,... i + 3] = x
+  //    a[i,... i + 3] = [1,...1]
+  HInstruction* vstore1 = AddVecStore(loop_, array_a, phi_);
+  HInstruction* vload = AddVecLoad(loop_, array_a, phi_);
+  AddVecStore(loop_, array_b, phi_, vload->AsVecLoad());
+  HInstruction* vstore3 = AddVecStore(loop_, array_a, phi_, vstore1->InputAt(2));
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vstore1));
+  ASSERT_TRUE(IsRemoved(vload));
+  ASSERT_TRUE(IsRemoved(vstore3));
+}
+
+// Loop write side effects invalidate all stores.
+// This causes stores after such loops not to be removed, even
+// their values are known.
+TEST_F(LoadStoreEliminationTest, StoreAfterLoopWithSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c2 = graph_->GetIntConstant(2);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  // array[0] = 2;
+  // loop:
+  //   b[i] = array[i]
+  // array[0] = 2
+  AddArraySet(entry_block_, array_, c0, c2);
+
+  HInstruction* array_b = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_b, pre_header_->GetLastInstruction());
+  array_b->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  HInstruction* load = AddArrayGet(loop_, array_, phi_);
+  AddArraySet(loop_, array_b, phi_, load);
+
+  HInstruction* store = AddArraySet(return_block_, array_, c0, c2);
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(store));
+}
+
+// As it is not allowed to use defaults for VecLoads, check if there is a new created array
+// a VecLoad used in a loop and after it is not replaced with a default.
+TEST_F(LoadStoreEliminationTest, VLoadDefaultValueInLoopWithoutWriteSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // LOOP BODY:
+  //    v = a[i,... i + 3]
+  // array[0,... 3] = v
+  HInstruction* vload = AddVecLoad(loop_, array_a, phi_);
+  HInstruction* vstore = AddVecStore(return_block_, array_, c0, vload->AsVecLoad());
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload));
+  ASSERT_FALSE(IsRemoved(vstore));
+}
+
+// As it is not allowed to use defaults for VecLoads, check if there is a new created array
+// a VecLoad is not replaced with a default.
+TEST_F(LoadStoreEliminationTest, VLoadDefaultValue) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // v = a[0,... 3]
+  // array[0,... 3] = v
+  HInstruction* vload = AddVecLoad(pre_header_, array_a, c0);
+  HInstruction* vstore = AddVecStore(return_block_, array_, c0, vload->AsVecLoad());
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload));
+  ASSERT_FALSE(IsRemoved(vstore));
+}
+
+// As it is allowed to use defaults for ordinary loads, check if there is a new created array
+// a load used in a loop and after it is replaced with a default.
+TEST_F(LoadStoreEliminationTest, LoadDefaultValueInLoopWithoutWriteSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // LOOP BODY:
+  //    v = a[i]
+  // array[0] = v
+  HInstruction* load = AddArrayGet(loop_, array_a, phi_);
+  HInstruction* store = AddArraySet(return_block_, array_, c0, load);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(load));
+  ASSERT_FALSE(IsRemoved(store));
+}
+
+// As it is allowed to use defaults for ordinary loads, check if there is a new created array
+// a load is replaced with a default.
+TEST_F(LoadStoreEliminationTest, LoadDefaultValue) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // v = a[0]
+  // array[0] = v
+  HInstruction* load = AddArrayGet(pre_header_, array_a, c0);
+  HInstruction* store = AddArraySet(return_block_, array_, c0, load);
+
+  PerformLSE();
+
+  ASSERT_TRUE(IsRemoved(load));
+  ASSERT_FALSE(IsRemoved(store));
+}
+
+// As it is not allowed to use defaults for VecLoads but allowed for regular loads,
+// check if there is a new created array, a VecLoad and a load used in a loop and after it,
+// VecLoad is not replaced with a default but the load is.
+TEST_F(LoadStoreEliminationTest, VLoadAndLoadDefaultValueInLoopWithoutWriteSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // LOOP BODY:
+  //    v = a[i,... i + 3]
+  //    v1 = a[i]
+  // array[0,... 3] = v
+  // array[0] = v1
+  HInstruction* vload = AddVecLoad(loop_, array_a, phi_);
+  HInstruction* load = AddArrayGet(loop_, array_a, phi_);
+  HInstruction* vstore = AddVecStore(return_block_, array_, c0, vload->AsVecLoad());
+  HInstruction* store = AddArraySet(return_block_, array_, c0, load);
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload));
+  ASSERT_TRUE(IsRemoved(load));
+  ASSERT_FALSE(IsRemoved(vstore));
+  ASSERT_FALSE(IsRemoved(store));
+}
+
+// As it is not allowed to use defaults for VecLoads but allowed for regular loads,
+// check if there is a new created array, a VecLoad and a load,
+// VecLoad is not replaced with a default but the load is.
+TEST_F(LoadStoreEliminationTest, VLoadAndLoadDefaultValue) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // v = a[0,... 3]
+  // v1 = a[0]
+  // array[0,... 3] = v
+  // array[0] = v1
+  HInstruction* vload = AddVecLoad(pre_header_, array_a, c0);
+  HInstruction* load = AddArrayGet(pre_header_, array_a, c0);
+  HInstruction* vstore = AddVecStore(return_block_, array_, c0, vload->AsVecLoad());
+  HInstruction* store = AddArraySet(return_block_, array_, c0, load);
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload));
+  ASSERT_TRUE(IsRemoved(load));
+  ASSERT_FALSE(IsRemoved(vstore));
+  ASSERT_FALSE(IsRemoved(store));
+}
+
+// It is not allowed to use defaults for VecLoads. However it should not prevent from removing
+// loads getting the same value.
+// Check a load getting a known value is eliminated (a loop test case).
+TEST_F(LoadStoreEliminationTest, VLoadDefaultValueAndVLoadInLoopWithoutWriteSideEffects) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // LOOP BODY:
+  //    v = a[i,... i + 3]
+  //    v1 = a[i,... i + 3]
+  // array[0,... 3] = v
+  // array[128,... 131] = v1
+  HInstruction* vload1 = AddVecLoad(loop_, array_a, phi_);
+  HInstruction* vload2 = AddVecLoad(loop_, array_a, phi_);
+  HInstruction* vstore1 = AddVecStore(return_block_, array_, c0, vload1->AsVecLoad());
+  HInstruction* vstore2 = AddVecStore(return_block_, array_, c128, vload2->AsVecLoad());
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload1));
+  ASSERT_TRUE(IsRemoved(vload2));
+  ASSERT_FALSE(IsRemoved(vstore1));
+  ASSERT_FALSE(IsRemoved(vstore2));
+}
+
+// It is not allowed to use defaults for VecLoads. However it should not prevent from removing
+// loads getting the same value.
+// Check a load getting a known value is eliminated.
+TEST_F(LoadStoreEliminationTest, VLoadDefaultValueAndVLoad) {
+  InitGraph();
+  CreateTestControlFlowGraph();
+
+  HInstruction* c0 = graph_->GetIntConstant(0);
+  HInstruction* c128 = graph_->GetIntConstant(128);
+
+  HInstruction* array_a = new (GetAllocator()) HNewArray(c0, c128, 0, 0);
+  pre_header_->InsertInstructionBefore(array_a, pre_header_->GetLastInstruction());
+  array_a->CopyEnvironmentFrom(suspend_check_->GetEnvironment());
+
+  // v = a[0,... 3]
+  // v1 = a[0,... 3]
+  // array[0,... 3] = v
+  // array[128,... 131] = v1
+  HInstruction* vload1 = AddVecLoad(pre_header_, array_a, c0);
+  HInstruction* vload2 = AddVecLoad(pre_header_, array_a, c0);
+  HInstruction* vstore1 = AddVecStore(return_block_, array_, c0, vload1->AsVecLoad());
+  HInstruction* vstore2 = AddVecStore(return_block_, array_, c128, vload2->AsVecLoad());
+
+  PerformLSE();
+
+  ASSERT_FALSE(IsRemoved(vload1));
+  ASSERT_TRUE(IsRemoved(vload2));
+  ASSERT_FALSE(IsRemoved(vstore1));
+  ASSERT_FALSE(IsRemoved(vstore2));
+}
+
+}  // namespace art