Reviewers: Lasse Reichstein, Michail Naganov,
Message:
Next step is to use the FixedArrayBuilder to only search through each script
once instead of twice. Let's first see if this change has any performance
impact, though.
Description:
Leverage Lasse's StringSearch object to speed up calculations of script
line ends.
Please review this at http://codereview.chromium.org/5100002/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/handles.cc
Index: src/handles.cc
===================================================================
--- src/handles.cc (revision 5837)
+++ src/handles.cc (working copy)
@@ -36,6 +36,7 @@
#include "execution.h"
#include "global-handles.h"
#include "natives.h"
+#include "string-search.h"
#include "runtime.h"
#include "stub-cache.h"
@@ -504,22 +505,21 @@
}
-Handle<FixedArray> CalculateLineEnds(Handle<String> src,
- bool with_imaginary_last_new_line) {
- const int src_len = src->length();
- Handle<String> new_line = Factory::NewStringFromAscii(CStrVector("\n"));
+template <typename SourceChar>
+Handle<FixedArray> CalculateLineEnds(Vector<const SourceChar> src,
+ bool with_last_line) {
+ const int src_len = src.length();
+ StringSearch<char, SourceChar> search(CStrVector("\n"));
// Pass 1: Identify line count.
int line_count = 0;
int position = 0;
while (position != -1 && position < src_len) {
- position = Runtime::StringMatch(src, new_line, position);
+ position = search.Search(src, position);
if (position != -1) {
position++;
- }
- if (position != -1) {
line_count++;
- } else if (with_imaginary_last_new_line) {
+ } else if (with_last_line) {
// Even if the last line misses a line end, it is counted.
line_count++;
}
@@ -530,10 +530,10 @@
int array_index = 0;
position = 0;
while (position != -1 && position < src_len) {
- position = Runtime::StringMatch(src, new_line, position);
+ position = search.Search(src, position);
if (position != -1) {
array->set(array_index++, Smi::FromInt(position++));
- } else if (with_imaginary_last_new_line) {
+ } else if (with_last_line) {
// If the script does not end with a line ending add the final end
// position as just past the last line ending.
array->set(array_index++, Smi::FromInt(src_len));
@@ -544,7 +544,22 @@
return array;
}
+Handle<FixedArray> CalculateLineEnds(Handle<String> src,
+ bool with_last_line) {
+ // const int src_len = src->length();
+ if (!src->IsFlat()) FlattenString(src);
+ AssertNoAllocation no_heap_allocation; // ensure vectors stay valid
+ // Extract flattened substrings of cons strings before determining
asciiness.
+ String* seq_src = *src;
+ if (seq_src->IsConsString()) seq_src =
ConsString::cast(seq_src)->first();
+ // dispatch on type of strings
+ if (seq_src->IsAsciiRepresentation()) {
+ return CalculateLineEnds(seq_src->ToAsciiVector(), with_last_line);
+ }
+ return CalculateLineEnds(seq_src->ToUC16Vector(), with_last_line);
+}
+
// Convert code position into line number.
int GetScriptLineNumber(Handle<Script> script, int code_pos) {
InitScriptLineEnds(script);
--
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