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

src/compiler/bytecode-loop-analysis.h

-// 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_LOOP_ANALYSIS_H_
-#define V8_COMPILER_BYTECODE_LOOP_ANALYSIS_H_
-
-#include "src/handles.h"
-#include "src/zone/zone-containers.h"
-
-namespace v8 {
-namespace internal {
-
-class BytecodeArray;
-
-namespace compiler {
-
-class BytecodeBranchAnalysis;
-
-class BytecodeLoopAnalysis BASE_EMBEDDED {
- public:
-  BytecodeLoopAnalysis(Handle<BytecodeArray> bytecode_array,
-                       const BytecodeBranchAnalysis* branch_analysis,
-                       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();
-
-  // Get the loop header offset of the containing loop for arbitrary
-  // {offset}, or -1 if the {offset} is not inside any loop.
-  int GetLoopOffsetFor(int offset) const;
-  // Gets the loop header offset of the parent loop of the loop header
-  // at {header_offset}, or -1 for outer-most loops.
-  int GetParentLoopFor(int header_offset) const;
-
- private:
-  void AddLoopEntry(int entry_offset);
-  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_;
-  const BytecodeBranchAnalysis* branch_analysis_;
-  Zone* zone_;
-
-  int current_loop_offset_;
-  bool found_current_backedge_;
-
-  // Map from the offset of a backedge jump to the offset of the corresponding
-  // loop header. There might be multiple backedges for do-while loops.
-  ZoneMap<int, int> backedge_to_header_;
-  // Map from the offset of a loop header to the offset of its parent's loop
-  // header. This map will have as many entries as there are loops in the
-  // function.
-  ZoneMap<int, int> loop_header_to_parent_;
-
-  DISALLOW_COPY_AND_ASSIGN(BytecodeLoopAnalysis);
-};
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_COMPILER_BYTECODE_LOOP_ANALYSIS_H_