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- Cache on backtracking stack in the irregexp interpreter for future use.

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Review URL: http://codereview.chromium.org/149131

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2341 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
iposva@chromium.org 2009-07-02 19:46:28 +00:00
parent 1e3bd893d3
commit c15df35204
1 changed files with 50 additions and 7 deletions
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57
src/interpreter-irregexp.cc
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@ -142,6 +142,49 @@ static int32_t Load16Aligned(const byte* pc) {
}
// 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 @@ static bool RawMatch(const byte* code_base,
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 @@ static bool RawMatch(const byte* code_base,
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;