1 // Copyright 2009 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_REGEXP_STACK_H_ 29 #define V8_REGEXP_STACK_H_ 30 31 namespace v8 { 32 namespace internal { 33 34 class RegExpStack; 35 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 { 42 public: 43 // Create and delete an instance to control the life-time of a growing stack. 44 45 // Initializes the stack memory area if necessary. 46 explicit RegExpStackScope(Isolate* isolate); 47 ~RegExpStackScope(); // Releases the stack if it has grown. 48 49 RegExpStack* stack() const { return regexp_stack_; } 50 51 private: 52 RegExpStack* regexp_stack_; 53 54 DISALLOW_COPY_AND_ASSIGN(RegExpStackScope); 55 }; 56 57 58 class RegExpStack { 59 public: 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 62 // check. 63 static const int kStackLimitSlack = 32; 64 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_; 69 } 70 71 // The total size of the memory allocated for the stack. 72 size_t stack_capacity() { return thread_local_.memory_size_; } 73 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_); } 80 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); 84 85 // Thread local archiving. 86 static int ArchiveSpacePerThread() { 87 return static_cast<int>(sizeof(ThreadLocal)); 88 } 89 char* ArchiveStack(char* to); 90 char* RestoreStack(char* from); 91 void FreeThreadResources() { thread_local_.Free(); } 92 93 private: 94 RegExpStack(); 95 ~RegExpStack(); 96 97 // Artificial limit used when no memory has been allocated. 98 static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1); 99 100 // Minimal size of allocated stack area. 101 static const size_t kMinimumStackSize = 1 * KB; 102 103 // Maximal size of allocated stack area. 104 static const size_t kMaximumStackSize = 64 * MB; 105 106 // Structure holding the allocated memory, size and limit. 107 struct ThreadLocal { 108 ThreadLocal() { Clear(); } 109 // If memory_size_ > 0 then memory_ must be non-NULL. 110 Address memory_; 111 size_t memory_size_; 112 Address limit_; 113 void Clear() { 114 memory_ = NULL; 115 memory_size_ = 0; 116 limit_ = reinterpret_cast<Address>(kMemoryTop); 117 } 118 void Free(); 119 }; 120 121 // Address of allocated memory. 122 Address memory_address() { 123 return reinterpret_cast<Address>(&thread_local_.memory_); 124 } 125 126 // Address of size of allocated memory. 127 Address memory_size_address() { 128 return reinterpret_cast<Address>(&thread_local_.memory_size_); 129 } 130 131 // 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. 134 void Reset(); 135 136 ThreadLocal thread_local_; 137 Isolate* isolate_; 138 139 friend class ExternalReference; 140 friend class Isolate; 141 friend class RegExpStackScope; 142 143 DISALLOW_COPY_AND_ASSIGN(RegExpStack); 144 }; 145 146 }} // namespace v8::internal 147 148 #endif // V8_REGEXP_STACK_H_ 149
