1 files changed, 103 insertions, 0 deletions
diff --git a/compiler/optimizing/escape.cc b/compiler/optimizing/escape.cc
new file mode 100644
index 0000000000..9df5bf1017
--- /dev/null
+++ b/compiler/optimizing/escape.cc
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2016 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 "escape.h"
+
+#include "nodes.h"
+
+namespace art {
+
+void CalculateEscape(HInstruction* reference,
+                     bool (*no_escape)(HInstruction*, HInstruction*),
+                     /*out*/ bool* is_singleton,
+                     /*out*/ bool* is_singleton_and_not_returned,
+                     /*out*/ bool* is_singleton_and_not_deopt_visible) {
+  // For references not allocated in the method, don't assume anything.
+  if (!reference->IsNewInstance() && !reference->IsNewArray()) {
+    *is_singleton = false;
+    *is_singleton_and_not_returned = false;
+    *is_singleton_and_not_deopt_visible = false;
+    return;
+  }
+  // Assume the best until proven otherwise.
+  *is_singleton = true;
+  *is_singleton_and_not_returned = true;
+  *is_singleton_and_not_deopt_visible = true;
+  // Visit all uses to determine if this reference can escape into the heap,
+  // a method call, an alias, etc.
+  for (const HUseListNode<HInstruction*>& use : reference->GetUses()) {
+    HInstruction* user = use.GetUser();
+    if (no_escape != nullptr && (*no_escape)(reference, user)) {
+      // Client supplied analysis says there is no escape.
+      continue;
+    } else if (user->IsBoundType() || user->IsNullCheck()) {
+      // BoundType shouldn't normally be necessary for an allocation. Just be conservative
+      // for the uncommon cases. Similarly, null checks are eventually eliminated for explicit
+      // allocations, but if we see one before it is simplified, assume an alias.
+      *is_singleton = false;
+      *is_singleton_and_not_returned = false;
+      *is_singleton_and_not_deopt_visible = false;
+      return;
+    } else if (user->IsPhi() || user->IsSelect() || user->IsInvoke() ||
+               (user->IsInstanceFieldSet() && (reference == user->InputAt(1))) ||
+               (user->IsUnresolvedInstanceFieldSet() && (reference == user->InputAt(1))) ||
+               (user->IsStaticFieldSet() && (reference == user->InputAt(1))) ||
+               (user->IsUnresolvedStaticFieldSet() && (reference == user->InputAt(0))) ||
+               (user->IsArraySet() && (reference == user->InputAt(2)))) {
+      // The reference is merged to HPhi/HSelect, passed to a callee, or stored to heap.
+      // Hence, the reference is no longer the only name that can refer to its value.
+      *is_singleton = false;
+      *is_singleton_and_not_returned = false;
+      *is_singleton_and_not_deopt_visible = false;
+      return;
+    } else if ((user->IsUnresolvedInstanceFieldGet() && (reference == user->InputAt(0))) ||
+               (user->IsUnresolvedInstanceFieldSet() && (reference == user->InputAt(0)))) {
+      // The field is accessed in an unresolved way. We mark the object as a non-singleton.
+      // Note that we could optimize this case and still perform some optimizations until
+      // we hit the unresolved access, but the conservative assumption is the simplest.
+      *is_singleton = false;
+      *is_singleton_and_not_returned = false;
+      *is_singleton_and_not_deopt_visible = false;
+      return;
+    } else if (user->IsReturn()) {
+      *is_singleton_and_not_returned = false;
+    }
+  }
+
+  // Look at the environment uses if it's for HDeoptimize. Other environment uses are fine,
+  // as long as client optimizations that rely on this information are disabled for debuggable.
+  for (const HUseListNode<HEnvironment*>& use : reference->GetEnvUses()) {
+    HEnvironment* user = use.GetUser();
+    if (user->GetHolder()->IsDeoptimize()) {
+      *is_singleton_and_not_deopt_visible = false;
+      break;
+    }
+  }
+}
+
+bool DoesNotEscape(HInstruction* reference, bool (*no_escape)(HInstruction*, HInstruction*)) {
+  bool is_singleton = false;
+  bool is_singleton_and_not_returned = false;
+  bool is_singleton_and_not_deopt_visible = false;  // not relevant for escape
+  CalculateEscape(reference,
+                  no_escape,
+                  &is_singleton,
+                  &is_singleton_and_not_returned,
+                  &is_singleton_and_not_deopt_visible);
+  return is_singleton_and_not_returned;
+}
+
+}  // namespace art