* Move irregexp backtrack stack to external memory area, instead of the system stack.

src/regexp-stack.h

Index: src/regexp-stack.h
diff --git a/src/regexp-stack.h b/src/regexp-stack.h
new file mode 100644
index 0000000000000000000000000000000000000000..a9d1ede40afdb68a98e5994771319bad1c770e63
--- /dev/null
+++ b/src/regexp-stack.h
@@ -0,0 +1,108 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef REGEXP_STACK_H_
+#define REGEXP_STACK_H_
+
+namespace v8 { namespace internal {
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+// Since there is only one stack area, the Irregexp implementation is not
+// re-entrant. I.e., no regular expressions may be executed in the same thread
+// during a preempted Irregexp execution.
+class RegExpStack {
+ public:
+  // Number of allocated locations on the stack below the limit.
+  // No sequence of pushes must be longer that this without doing a stack-limit
+  // check.
+  static const int kStackLimitSlack = 32;
+
+  // Create and delete an instance to control the life-time of a growing stack.
+  RegExpStack();  // Initializes the stack memory area if necessary.
+  ~RegExpStack();  // Releases the stack if it has grown.
+
+  // Gives the top of the memory used as stack.
+  static Address stack_top() {
+    ASSERT(thread_local_.memory_size_ != 0);
+    return thread_local_.memory_ + thread_local_.memory_size_;
+  }
+
+  // The total size of the memory allocated for the stack.
+  static size_t stack_capacity() { 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.
+  static Address* limit_address() {
+    return &(thread_local_.limit_);

[Erik Corry, 2009/01/12 11:50:13]

This looks like it would all fit on one line.

[Lasse Reichstein, 2009/01/12 13:03:59]

Done.

+  }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  static Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static size_t ArchiveSpacePerThread() { return sizeof(thread_local_); }
+  static char* ArchiveStack(char* to);
+  static char* RestoreStack(char* from);
+
+ private:
+  // Artificial limit used when no memory has been allocated.
+  static const uint32_t kMemoryTop = 0xffffffff;
+
+  // Minimal size of allocated stack area.
+  static const size_t kMinimumStackSize = 1 * KB;
+
+  // Maximal size of allocated stack area.
+  static const size_t kMaximumStackSize = 256 * KB;
+
+  // Structure holding the allocated memory, size and limit.
+  struct ThreadLocal {
+    ThreadLocal()
+        : memory_(NULL),
+          memory_size_(0),
+          limit_(reinterpret_cast<Address>(kMemoryTop)) {}
+    // If memory_size_ > 0 then memory_ must be non-NULL.
+    Address memory_;
+    size_t memory_size_;
+    Address limit_;
+  };
+
+  // Resets the buffer if it has grown beyond the default/minimum size.
+  // After this, the buffer is either the default size, or it is empty, so
+  // you have to call EnsureCapacity before using it again.
+  static void Reset();
+
+  static ThreadLocal thread_local_;
+};
+
+}}  // namespace v8::internal
+
+#endif /* REGEXP_STACK_H_ */