[ignition] Replace branch+loop analysis with a single pass

src/compiler/bytecode-branch-analysis.h

-// Copyright 2015 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_BRANCH_ANALYSIS_H_
-#define V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_
-
-#include "src/bit-vector.h"
-#include "src/handles.h"
-
-namespace v8 {
-namespace internal {
-
-class BytecodeArray;
-
-namespace compiler {
-
-// A class for identifying branch targets within a bytecode array.
-// This information can be used to construct the local control flow
-// logic for high-level IR graphs built from bytecode.
-//
-// N.B. If this class is used to determine loop headers, then such a
-// usage relies on the only backwards branches in bytecode being jumps
-// back to loop headers.
-class BytecodeBranchAnalysis BASE_EMBEDDED {
- public:
-  BytecodeBranchAnalysis(Handle<BytecodeArray> bytecode_array, Zone* zone);
-
-  // Analyze the bytecodes to find the branch sites and their
-  // targets. No other methods in this class return valid information
-  // until this has been called.
-  void Analyze();
-
-  // Returns true if there are any forward branches to the bytecode at
-  // |offset|.
-  bool forward_branches_target(int offset) const {
-    return is_forward_target_.Contains(offset);
-  }
-
-  // Returns true if there are any backward branches to the bytecode
-  // at |offset|.
-  bool backward_branches_target(int offset) const {
-    return is_backward_target_.Contains(offset);
-  }
-
- private:
-  void AddBranch(int origin_offset, int target_offset);
-
-  Zone* zone() const { return zone_; }
-  Handle<BytecodeArray> bytecode_array() const { return bytecode_array_; }
-
-  Handle<BytecodeArray> bytecode_array_;
-  BitVector is_backward_target_;
-  BitVector is_forward_target_;
-  Zone* zone_;
-
-  DISALLOW_COPY_AND_ASSIGN(BytecodeBranchAnalysis);
-};
-
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_COMPILER_BYTECODE_BRANCH_ANALYSIS_H_