1 files changed, 49 insertions, 19 deletions

diff --git a/compiler/optimizing/select_generator.cc b/compiler/optimizing/select_generator.cc
index cb7ade915f..e220d32344 100644
--- a/compiler/optimizing/select_generator.cc
+++ b/compiler/optimizing/select_generator.cc
@@ -20,9 +20,16 @@ namespace art {
 
 static constexpr size_t kMaxInstructionsInBranch = 1u;
 
-// Returns true if `block` has only one predecessor, ends with a Goto and
-// contains at most `kMaxInstructionsInBranch` other movable instruction with
-// no side-effects.
+HSelectGenerator::HSelectGenerator(HGraph* graph,
+                                   VariableSizedHandleScope* handles,
+                                   OptimizingCompilerStats* stats)
+    : HOptimization(graph, kSelectGeneratorPassName, stats),
+      handle_scope_(handles) {
+}
+
+// Returns true if `block` has only one predecessor, ends with a Goto
+// or a Return and contains at most `kMaxInstructionsInBranch` other
+// movable instruction with no side-effects.
 static bool IsSimpleBlock(HBasicBlock* block) {
   if (block->GetPredecessors().size() != 1u) {
     return false;
@@ -33,7 +40,10 @@ static bool IsSimpleBlock(HBasicBlock* block) {
   for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
     HInstruction* instruction = it.Current();
     if (instruction->IsControlFlow()) {
-      return instruction->IsGoto() && num_instructions <= kMaxInstructionsInBranch;
+      if (num_instructions > kMaxInstructionsInBranch) {
+        return false;
+      }
+      return instruction->IsGoto() || instruction->IsReturn();
     } else if (instruction->CanBeMoved() && !instruction->HasSideEffects()) {
       num_instructions++;
     } else {
@@ -45,8 +55,8 @@ static bool IsSimpleBlock(HBasicBlock* block) {
   UNREACHABLE();
 }
 
-// Returns true if 'block1' and 'block2' are empty, merge into the same single
-// successor and the successor can only be reached from them.
+// Returns true if 'block1' and 'block2' are empty and merge into the
+// same single successor.
 static bool BlocksMergeTogether(HBasicBlock* block1, HBasicBlock* block2) {
   return block1->GetSingleSuccessor() == block2->GetSingleSuccessor();
 }
@@ -94,48 +104,68 @@ void HSelectGenerator::Run() {
     // If the branches are not empty, move instructions in front of the If.
     // TODO(dbrazdil): This puts an instruction between If and its condition.
     //                 Implement moving of conditions to first users if possible.
-    if (!true_block->IsSingleGoto()) {
+    if (!true_block->IsSingleGoto() && !true_block->IsSingleReturn()) {
       true_block->GetFirstInstruction()->MoveBefore(if_instruction);
     }
-    if (!false_block->IsSingleGoto()) {
+    if (!false_block->IsSingleGoto() && !false_block->IsSingleReturn()) {
       false_block->GetFirstInstruction()->MoveBefore(if_instruction);
     }
-    DCHECK(true_block->IsSingleGoto());
-    DCHECK(false_block->IsSingleGoto());
+    DCHECK(true_block->IsSingleGoto() || true_block->IsSingleReturn());
+    DCHECK(false_block->IsSingleGoto() || false_block->IsSingleReturn());
 
     // Find the resulting true/false values.
     size_t predecessor_index_true = merge_block->GetPredecessorIndexOf(true_block);
     size_t predecessor_index_false = merge_block->GetPredecessorIndexOf(false_block);
     DCHECK_NE(predecessor_index_true, predecessor_index_false);
 
+    bool both_successors_return = true_block->IsSingleReturn() && false_block->IsSingleReturn();
     HPhi* phi = GetSingleChangedPhi(merge_block, predecessor_index_true, predecessor_index_false);
-    if (phi == nullptr) {
+
+    HInstruction* true_value = nullptr;
+    HInstruction* false_value = nullptr;
+    if (both_successors_return) {
+      true_value = true_block->GetFirstInstruction()->InputAt(0);
+      false_value = false_block->GetFirstInstruction()->InputAt(0);
+    } else if (phi != nullptr) {
+      true_value = phi->InputAt(predecessor_index_true);
+      false_value = phi->InputAt(predecessor_index_false);
+    } else {
       continue;
     }
-    HInstruction* true_value = phi->InputAt(predecessor_index_true);
-    HInstruction* false_value = phi->InputAt(predecessor_index_false);
+    DCHECK(both_successors_return || phi != nullptr);
 
     // Create the Select instruction and insert it in front of the If.
     HSelect* select = new (graph_->GetArena()) HSelect(if_instruction->InputAt(0),
                                                        true_value,
                                                        false_value,
                                                        if_instruction->GetDexPc());
-    if (phi->GetType() == Primitive::kPrimNot) {
+    if (both_successors_return) {
+      if (true_value->GetType() == Primitive::kPrimNot) {
+        DCHECK(false_value->GetType() == Primitive::kPrimNot);
+        ReferenceTypePropagation::FixUpInstructionType(select, handle_scope_);
+      }
+    } else if (phi->GetType() == Primitive::kPrimNot) {
       select->SetReferenceTypeInfo(phi->GetReferenceTypeInfo());
     }
     block->InsertInstructionBefore(select, if_instruction);
 
-    // Remove the true branch which removes the corresponding Phi input.
-    // If left only with the false branch, the Phi is automatically removed.
-    phi->ReplaceInput(select, predecessor_index_false);
+    // Remove the true branch which removes the corresponding Phi
+    // input if needed. If left only with the false branch, the Phi is
+    // automatically removed.
+    if (both_successors_return) {
+      false_block->GetFirstInstruction()->ReplaceInput(select, 0);
+    } else {
+      phi->ReplaceInput(select, predecessor_index_false);
+    }
+
     bool only_two_predecessors = (merge_block->GetPredecessors().size() == 2u);
     true_block->DisconnectAndDelete();
-    DCHECK_EQ(only_two_predecessors, phi->GetBlock() == nullptr);
 
     // Merge remaining blocks which are now connected with Goto.
     DCHECK_EQ(block->GetSingleSuccessor(), false_block);
     block->MergeWith(false_block);
-    if (only_two_predecessors) {
+    if (!both_successors_return && only_two_predecessors) {
+      DCHECK_EQ(only_two_predecessors, phi->GetBlock() == nullptr);
       DCHECK_EQ(block->GetSingleSuccessor(), merge_block);
       block->MergeWith(merge_block);
     }