Reland of [ignition/turbo] Perform liveness analysis on the bytecodes

src/compiler/bytecode-liveness-map.h

Index: src/compiler/bytecode-liveness-map.h
diff --git a/src/compiler/bytecode-liveness-map.h b/src/compiler/bytecode-liveness-map.h
new file mode 100644
index 0000000000000000000000000000000000000000..e5c7a38996539d388d062f73caf890d085159cb2
--- /dev/null
+++ b/src/compiler/bytecode-liveness-map.h
@@ -0,0 +1,55 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_COMPILER_BYTECODE_LIVENESS_MAP_H_
+#define V8_COMPILER_BYTECODE_LIVENESS_MAP_H_
+
+#include "src/base/hashmap.h"
+#include "src/bit-vector.h"
+#include "src/zone/zone.h"
+
+namespace v8 {
+namespace internal {
+
+class Zone;
+
+namespace compiler {
+
+struct Liveness {
+  BitVector* in;
+  BitVector* out;
+
+  Liveness(int size, Zone* zone);
+};
+
+class V8_EXPORT_PRIVATE BytecodeLivenessMap {
+ public:
+  BytecodeLivenessMap(int size, Zone* zone);
+
+  Liveness& InitializeLiveness(int offset, int size, Zone* zone);
+
+  Liveness& GetLiveness(int offset);
+  const Liveness& GetLiveness(int offset) const;
+
+  BitVector* GetInLiveness(int offset) { return GetLiveness(offset).in; }
+  const BitVector* GetInLiveness(int offset) const {
+    return GetLiveness(offset).in;
+  }
+
+  BitVector* GetOutLiveness(int offset) { return GetLiveness(offset).out; }
+  const BitVector* GetOutLiveness(int offset) const {
+    return GetLiveness(offset).out;
+  }
+
+ private:
+  base::TemplateHashMapImpl<int, Liveness, base::KeyEqualityMatcher<int>,
+                            ZoneAllocationPolicy>
+      liveness_map_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_BYTECODE_LIVENESS_MAP_H_