[interpreter] Simplify BytecodeBranchAnalysis to minimum.

src/compiler/bytecode-branch-analysis.cc

 // 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.
 
 #include "src/compiler/bytecode-branch-analysis.h"
 
 #include "src/interpreter/bytecode-array-iterator.h"
 #include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-// The class contains all of the sites that contain
-// branches to a particular target (bytecode offset).
-class BytecodeBranchInfo final : public ZoneObject {
- public:
-  explicit BytecodeBranchInfo(Zone* zone)
-      : back_edge_offsets_(zone), fore_edge_offsets_(zone) {}
-
-  void AddBranch(int source_offset, int target_offset);
-
-  // The offsets of bytecodes that refer to this bytecode as
-  // a back-edge predecessor.
-  const ZoneVector<int>* back_edge_offsets() { return &back_edge_offsets_; }
-
-  // The offsets of bytecodes that refer to this bytecode as
-  // a forwards-edge predecessor.
-  const ZoneVector<int>* fore_edge_offsets() { return &fore_edge_offsets_; }
-
- private:
-  ZoneVector<int> back_edge_offsets_;
-  ZoneVector<int> fore_edge_offsets_;
-
-  DISALLOW_COPY_AND_ASSIGN(BytecodeBranchInfo);
-};
-
-
-void BytecodeBranchInfo::AddBranch(int source_offset, int target_offset) {
-  if (source_offset < target_offset) {
-    fore_edge_offsets_.push_back(source_offset);
-  } else {
-    back_edge_offsets_.push_back(source_offset);
-  }
-}
-
-
 BytecodeBranchAnalysis::BytecodeBranchAnalysis(
     Handle<BytecodeArray> bytecode_array, Zone* zone)
-    : branch_infos_(zone),
-      bytecode_array_(bytecode_array),
+    : bytecode_array_(bytecode_array),
+      is_backward_target_(bytecode_array->length(), zone),
+      is_forward_target_(bytecode_array->length(), zone),
       zone_(zone) {}
 
-
 void BytecodeBranchAnalysis::Analyze() {
   interpreter::BytecodeArrayIterator iterator(bytecode_array());
   while (!iterator.done()) {
     interpreter::Bytecode bytecode = iterator.current_bytecode();
     int current_offset = iterator.current_offset();
     if (interpreter::Bytecodes::IsJump(bytecode)) {
       AddBranch(current_offset, iterator.GetJumpTargetOffset());
     }
     iterator.Advance();
   }
 }
 
-
-const ZoneVector<int>* BytecodeBranchAnalysis::BackwardBranchesTargetting(
-    int offset) const {
-  auto iterator = branch_infos_.find(offset);
-  if (branch_infos_.end() != iterator) {
-    return iterator->second->back_edge_offsets();
-  } else {
-    return nullptr;
-  }
-}
-
-
-const ZoneVector<int>* BytecodeBranchAnalysis::ForwardBranchesTargetting(
-    int offset) const {
-  auto iterator = branch_infos_.find(offset);
-  if (branch_infos_.end() != iterator) {
-    return iterator->second->fore_edge_offsets();
-  } else {
-    return nullptr;
-  }
-}
-
 void BytecodeBranchAnalysis::AddBranch(int source_offset, int target_offset) {
-  BytecodeBranchInfo* branch_info = nullptr;
-  auto iterator = branch_infos_.find(target_offset);
-  if (branch_infos_.end() == iterator) {
-    branch_info = new (zone()) BytecodeBranchInfo(zone());
-    branch_infos_.insert(std::make_pair(target_offset, branch_info));
+  if (source_offset < target_offset) {
+    is_forward_target_.Add(target_offset);
   } else {
-    branch_info = iterator->second;
+    is_backward_target_.Add(target_offset);
   }
-  branch_info->AddBranch(source_offset, target_offset);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8