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 // Maintains a per-v8thread stack area that can be used by irregexp 35 // implementation for its backtracking stack. 36 // Since there is only one stack area, the Irregexp implementation is not 37 // re-entrant. I.e., no regular expressions may be executed in the same thread 38 // during a preempted Irregexp execution. 39 class RegExpStack { 40 public: 41 // Number of allocated locations on the stack below the limit. 42 // No sequence of pushes must be longer that this without doing a stack-limit 43 // check. 44 static const int kStackLimitSlack = 32; 45 46 // Create and delete an instance to control the life-time of a growing stack. 47 RegExpStack(); // Initializes the stack memory area if necessary. 48 ~RegExpStack(); // Releases the stack if it has grown. 49 50 // Gives the top of the memory used as stack. stack_base()51 static Address stack_base() { 52 ASSERT(thread_local_.memory_size_ != 0); 53 return thread_local_.memory_ + thread_local_.memory_size_; 54 } 55 56 // The total size of the memory allocated for the stack. stack_capacity()57 static size_t stack_capacity() { return thread_local_.memory_size_; } 58 59 // If the stack pointer gets below the limit, we should react and 60 // either grow the stack or report an out-of-stack exception. 61 // There is only a limited number of locations below the stack limit, 62 // so users of the stack should check the stack limit during any 63 // sequence of pushes longer that this. limit_address()64 static Address* limit_address() { return &(thread_local_.limit_); } 65 66 // Ensures that there is a memory area with at least the specified size. 67 // If passing zero, the default/minimum size buffer is allocated. 68 static Address EnsureCapacity(size_t size); 69 70 // Thread local archiving. ArchiveSpacePerThread()71 static size_t ArchiveSpacePerThread() { return sizeof(thread_local_); } 72 static char* ArchiveStack(char* to); 73 static char* RestoreStack(char* from); 74 75 private: 76 // Artificial limit used when no memory has been allocated. 77 static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1); 78 79 // Minimal size of allocated stack area. 80 static const size_t kMinimumStackSize = 1 * KB; 81 82 // Maximal size of allocated stack area. 83 static const size_t kMaximumStackSize = 64 * MB; 84 85 // Structure holding the allocated memory, size and limit. 86 struct ThreadLocal { ThreadLocalThreadLocal87 ThreadLocal() 88 : memory_(NULL), 89 memory_size_(0), 90 limit_(reinterpret_cast<Address>(kMemoryTop)) {} 91 // If memory_size_ > 0 then memory_ must be non-NULL. 92 Address memory_; 93 size_t memory_size_; 94 Address limit_; 95 }; 96 97 // Resets the buffer if it has grown beyond the default/minimum size. 98 // After this, the buffer is either the default size, or it is empty, so 99 // you have to call EnsureCapacity before using it again. 100 static void Reset(); 101 102 static ThreadLocal thread_local_; 103 }; 104 105 }} // namespace v8::internal 106 107 #endif // V8_REGEXP_STACK_H_ 108