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28 #ifndef V8_REGEXP_STACK_H_
29 #define V8_REGEXP_STACK_H_
36 // Maintains a per-v8thread stack area that can be used by irregexp
37 // implementation for its backtracking stack.
38 // Since there is only one stack area, the Irregexp implementation is not
39 // re-entrant. I.e., no regular expressions may be executed in the same thread
40 // during a preempted Irregexp execution.
41 class RegExpStackScope {
43 // Create and delete an instance to control the life-time of a growing stack.
45 // Initializes the stack memory area if necessary.
46 explicit RegExpStackScope(Isolate* isolate);
47 ~RegExpStackScope(); // Releases the stack if it has grown.
49 RegExpStack* stack() const { return regexp_stack_; }
52 RegExpStack* regexp_stack_;
54 DISALLOW_COPY_AND_ASSIGN(RegExpStackScope);
60 // Number of allocated locations on the stack below the limit.
61 // No sequence of pushes must be longer that this without doing a stack-limit
63 static const int kStackLimitSlack = 32;
65 // Gives the top of the memory used as stack.
66 Address stack_base() {
67 ASSERT(thread_local_.memory_size_ != 0);
68 return thread_local_.memory_ + thread_local_.memory_size_;
71 // The total size of the memory allocated for the stack.
72 size_t stack_capacity() { return thread_local_.memory_size_; }
74 // If the stack pointer gets below the limit, we should react and
75 // either grow the stack or report an out-of-stack exception.
76 // There is only a limited number of locations below the stack limit,
77 // so users of the stack should check the stack limit during any
78 // sequence of pushes longer that this.
79 Address* limit_address() { return &(thread_local_.limit_); }
81 // Ensures that there is a memory area with at least the specified size.
82 // If passing zero, the default/minimum size buffer is allocated.
83 Address EnsureCapacity(size_t size);
85 // Thread local archiving.
86 static int ArchiveSpacePerThread() {
87 return static_cast<int>(sizeof(ThreadLocal));
89 char* ArchiveStack(char* to);
90 char* RestoreStack(char* from);
91 void FreeThreadResources() { thread_local_.Free(); }
97 // Artificial limit used when no memory has been allocated.
98 static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1);
100 // Minimal size of allocated stack area.
101 static const size_t kMinimumStackSize = 1 * KB;
103 // Maximal size of allocated stack area.
104 static const size_t kMaximumStackSize = 64 * MB;
106 // Structure holding the allocated memory, size and limit.
108 ThreadLocal() { Clear(); }
109 // If memory_size_ > 0 then memory_ must be non-NULL.
116 limit_ = reinterpret_cast<Address>(kMemoryTop);
121 // Address of allocated memory.
122 Address memory_address() {
123 return reinterpret_cast<Address>(&thread_local_.memory_);
126 // Address of size of allocated memory.
127 Address memory_size_address() {
128 return reinterpret_cast<Address>(&thread_local_.memory_size_);
131 // Resets the buffer if it has grown beyond the default/minimum size.
132 // After this, the buffer is either the default size, or it is empty, so
133 // you have to call EnsureCapacity before using it again.
136 ThreadLocal thread_local_;
139 friend class ExternalReference;
140 friend class Isolate;
141 friend class RegExpStackScope;
143 DISALLOW_COPY_AND_ASSIGN(RegExpStack);
146 }} // namespace v8::internal
148 #endif // V8_REGEXP_STACK_H_