1 files changed, 159 insertions, 0 deletions
diff --git a/js/src/irregexp/imported/regexp-stack.h b/js/src/irregexp/imported/regexp-stack.h
new file mode 100644
index 0000000000..f03898bb00
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-stack.h
@@ -0,0 +1,159 @@
+// Copyright 2009 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_REGEXP_REGEXP_STACK_H_
+#define V8_REGEXP_REGEXP_STACK_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class RegExpStack;
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+class V8_NODISCARD RegExpStackScope final {
+ public:
+  // Create and delete an instance to control the life-time of a growing stack.
+
+  // Initializes the stack memory area if necessary.
+  explicit RegExpStackScope(Isolate* isolate);
+  ~RegExpStackScope();  // Releases the stack if it has grown.
+  RegExpStackScope(const RegExpStackScope&) = delete;
+  RegExpStackScope& operator=(const RegExpStackScope&) = delete;
+
+  RegExpStack* stack() const { return regexp_stack_; }
+
+ private:
+  RegExpStack* const regexp_stack_;
+  const ptrdiff_t old_sp_top_delta_;
+};
+
+class RegExpStack final {
+ public:
+  RegExpStack();
+  ~RegExpStack();
+  RegExpStack(const RegExpStack&) = delete;
+  RegExpStack& operator=(const RegExpStack&) = delete;
+
+  // Number of allocated locations on the stack below the limit. No sequence of
+  // pushes must be longer than this without doing a stack-limit check.
+  static constexpr int kStackLimitSlack = 32;
+
+  Address memory_top() const {
+    DCHECK_NE(0, thread_local_.memory_size_);
+    DCHECK_EQ(thread_local_.memory_top_,
+              thread_local_.memory_ + thread_local_.memory_size_);
+    return reinterpret_cast<Address>(thread_local_.memory_top_);
+  }
+
+  Address stack_pointer() const {
+    return reinterpret_cast<Address>(thread_local_.stack_pointer_);
+  }
+
+  size_t memory_size() const { return thread_local_.memory_size_; }
+
+  // If the stack pointer gets below the limit, we should react and
+  // either grow the stack or report an out-of-stack exception.
+  // There is only a limited number of locations below the stack limit,
+  // so users of the stack should check the stack limit during any
+  // sequence of pushes longer that this.
+  Address* limit_address_address() { return &thread_local_.limit_; }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static constexpr int ArchiveSpacePerThread() {
+    return static_cast<int>(kThreadLocalSize);
+  }
+  char* ArchiveStack(char* to);
+  char* RestoreStack(char* from);
+  void FreeThreadResources() { thread_local_.ResetToStaticStack(this); }
+
+  // Maximal size of allocated stack area.
+  static constexpr size_t kMaximumStackSize = 64 * MB;
+
+ private:
+  // Artificial limit used when the thread-local state has been destroyed.
+  static const Address kMemoryTop =
+      static_cast<Address>(static_cast<uintptr_t>(-1));
+
+  // Minimal size of dynamically-allocated stack area.
+  static constexpr size_t kMinimumDynamicStackSize = 1 * KB;
+
+  // In addition to dynamically-allocated, variable-sized stacks, we also have
+  // a statically allocated and sized area that is used whenever no dynamic
+  // stack is allocated. This guarantees that a stack is always available and
+  // we can skip availability-checks later on.
+  // It's double the slack size to ensure that we have a bit of breathing room
+  // before NativeRegExpMacroAssembler::GrowStack must be called.
+  static constexpr size_t kStaticStackSize =
+      2 * kStackLimitSlack * kSystemPointerSize;
+  byte static_stack_[kStaticStackSize] = {0};
+
+  static_assert(kStaticStackSize <= kMaximumStackSize);
+
+  // Structure holding the allocated memory, size and limit. Thread switching
+  // archives and restores this struct.
+  struct ThreadLocal {
+    explicit ThreadLocal(RegExpStack* regexp_stack) {
+      ResetToStaticStack(regexp_stack);
+    }
+
+    // If memory_size_ > 0 then
+    //  - memory_, memory_top_, stack_pointer_ must be non-nullptr
+    //  - memory_top_ = memory_ + memory_size_
+    //  - memory_ <= stack_pointer_ <= memory_top_
+    byte* memory_ = nullptr;
+    byte* memory_top_ = nullptr;
+    size_t memory_size_ = 0;
+    byte* stack_pointer_ = nullptr;
+    Address limit_ = kNullAddress;
+    bool owns_memory_ = false;  // Whether memory_ is owned and must be freed.
+
+    void ResetToStaticStack(RegExpStack* regexp_stack);
+    void ResetToStaticStackIfEmpty(RegExpStack* regexp_stack) {
+      if (stack_pointer_ == memory_top_) ResetToStaticStack(regexp_stack);
+    }
+    void FreeAndInvalidate();
+  };
+  static constexpr size_t kThreadLocalSize = sizeof(ThreadLocal);
+
+  Address memory_top_address_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_top_);
+  }
+
+  Address stack_pointer_address() {
+    return reinterpret_cast<Address>(&thread_local_.stack_pointer_);
+  }
+
+  // A position-independent representation of the stack pointer.
+  ptrdiff_t sp_top_delta() const {
+    ptrdiff_t result =
+        reinterpret_cast<intptr_t>(thread_local_.stack_pointer_) -
+        reinterpret_cast<intptr_t>(thread_local_.memory_top_);
+    DCHECK_LE(result, 0);
+    return result;
+  }
+
+  // Resets the buffer if it has grown beyond the default/minimum size and is
+  // empty.
+  void ResetIfEmpty() { thread_local_.ResetToStaticStackIfEmpty(this); }
+
+  // Whether the ThreadLocal storage has been invalidated.
+  bool IsValid() const { return thread_local_.memory_ != nullptr; }
+
+  ThreadLocal thread_local_;
+
+  friend class ExternalReference;
+  friend class RegExpStackScope;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_STACK_H_