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diff --git a/deps/v8/src/compiler/branch-condition-duplicator.h b/deps/v8/src/compiler/branch-condition-duplicator.h
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+// Copyright 2022 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_BRANCH_CONDITION_DUPLICATOR_H_
+#define V8_COMPILER_BRANCH_CONDITION_DUPLICATOR_H_
+
+#include "src/base/macros.h"
+#include "src/compiler/node-marker.h"
+#include "src/compiler/node.h"
+#include "src/zone/zone.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// Forward declare.
+class Graph;
+
+// BranchConditionDuplicator makes sure that the condition nodes of branches are
+// used only once. When it finds a branch node whose condition has multiples
+// uses, this condition is duplicated.
+//
+// Doing this enables the InstructionSelector to generate more efficient code
+// for branches. For instance, consider this code:
+//
+//     if (a + b == 0) { /* some code */ }
+//     if (a + b == 0) { /* more code */ }
+//
+// Then the generated code will be something like (using registers "ra" for "a"
+// and "rb" for "b", and "rt" a temporary register):
+//
+//     add ra, rb  ; a + b
+//     cmp ra, 0   ; (a + b) == 0
+//     sete rt     ; rt = (a + b) == 0
+//     cmp rt, 0   ; rt == 0
+//     jz
+//     ...
+//     cmp rt, 0   ; rt == 0
+//     jz
+//
+// As you can see, TurboFan materialized the == bit into a temporary register.
+// However, since the "add" instruction sets the ZF flag (on x64), it can be
+// used to determine wether the jump should be taken or not. The code we'd like
+// to generate instead if thus:
+//
+//     add ra, rb
+//     jnz
+//     ...
+//     add ra, rb
+//     jnz
+//
+// However, this requires to generate twice the instruction "add ra, rb". Due to
+// how virtual registers are assigned in TurboFan (there is a map from node ID
+// to virtual registers), both "add" instructions will use the same virtual
+// register as output, which will break SSA.
+//
+// In order to overcome this issue, BranchConditionDuplicator duplicates branch
+// conditions that are used more than once, so that they can be generated right
+// before each branch without worrying about breaking SSA.
+
+class V8_EXPORT_PRIVATE BranchConditionDuplicator final {
+ public:
+  BranchConditionDuplicator(Zone* zone, Graph* graph);
+  ~BranchConditionDuplicator() = default;
+
+  void Reduce();
+
+  Node* DuplicateNode(Node* node);
+  void DuplicateConditionIfNeeded(Node* node);
+  void Enqueue(Node* node);
+  void VisitNode(Node* node);
+  void ProcessGraph();
+
+ private:
+  Graph* const graph_;
+  ZoneQueue<Node*> to_visit_;
+  NodeMarker<bool> seen_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_BRANCH_CONDITION_DUPLICATOR_H_