Author: [email protected]
Date: Thu Jul 2 12:46:28 2009
New Revision: 2341
Modified:
branches/bleeding_edge/src/interpreter-irregexp.cc
Log:
- Cache on backtracking stack in the irregexp interpreter for future use.
Review URL: http://codereview.chromium.org/149131
Modified: branches/bleeding_edge/src/interpreter-irregexp.cc
==============================================================================
--- branches/bleeding_edge/src/interpreter-irregexp.cc (original)
+++ branches/bleeding_edge/src/interpreter-irregexp.cc Thu Jul 2 12:46:28
2009
@@ -142,6 +142,49 @@
}
+// A simple abstraction over the backtracking stack used by the
interpreter.
+// This backtracking stack does not grow automatically, but it ensures
that the
+// the memory held by the stack is released or remembered in a cache if the
+// matching terminates.
+class BacktrackStack {
+ public:
+ explicit BacktrackStack() {
+ if (cache_ != NULL) {
+ // If the cache is not empty reuse the previously allocated stack.
+ data_ = cache_;
+ cache_ = NULL;
+ } else {
+ // Cache was empty. Allocate a new backtrack stack.
+ data_ = NewArray<int>(kBacktrackStackSize);
+ }
+ }
+
+ ~BacktrackStack() {
+ if (cache_ == NULL) {
+ // The cache is empty. Keep this backtrack stack around.
+ cache_ = data_;
+ } else {
+ // A backtrack stack was already cached, just release this one.
+ DeleteArray(data_);
+ }
+ }
+
+ int* data() const { return data_; }
+
+ int max_size() const { return kBacktrackStackSize; }
+
+ private:
+ static const int kBacktrackStackSize = 10000;
+
+ int* data_;
+ static int* cache_;
+
+ DISALLOW_COPY_AND_ASSIGN(BacktrackStack);
+};
+
+int* BacktrackStack::cache_ = NULL;
+
+
template <typename Char>
static bool RawMatch(const byte* code_base,
Vector<const Char> subject,
@@ -149,13 +192,13 @@
int current,
uint32_t current_char) {
const byte* pc = code_base;
- static const int kBacktrackStackSize = 10000;
- // Use a SmartPointer here to ensure that the memory gets freed when the
- // matching finishes.
- SmartPointer<int> backtrack_stack(NewArray<int>(kBacktrackStackSize));
- int* backtrack_stack_base = *backtrack_stack;
+ // BacktrackStack ensures that the memory allocated for the backtracking
stack
+ // is returned to the system or cached if there is no stack being cached
at
+ // the moment.
+ BacktrackStack backtrack_stack;
+ int* backtrack_stack_base = backtrack_stack.data();
int* backtrack_sp = backtrack_stack_base;
- int backtrack_stack_space = kBacktrackStackSize;
+ int backtrack_stack_space = backtrack_stack.max_size();
#ifdef DEBUG
if (FLAG_trace_regexp_bytecodes) {
PrintF("\n\nStart bytecode interpreter\n\n");
@@ -210,7 +253,7 @@
break;
BYTECODE(SET_SP_TO_REGISTER)
backtrack_sp = backtrack_stack_base + registers[insn >>
BYTECODE_SHIFT];
- backtrack_stack_space = kBacktrackStackSize -
+ backtrack_stack_space = backtrack_stack.max_size() -
(backtrack_sp - backtrack_stack_base);
pc += BC_SET_SP_TO_REGISTER_LENGTH;
break;
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