Title: [209858] trunk/Source/WTF
- Revision
- 209858
- Author
- [email protected]
- Date
- 2016-12-15 02:28:55 -0800 (Thu, 15 Dec 2016)
Log Message
[JSC] Optimize Kraken stringify
https://bugs.webkit.org/show_bug.cgi?id=165857
Reviewed by Darin Adler.
Kraken json-stringify-tinderbox performance heavily relies on StringBuilder::appendQuotedJSONString.
According to the result produced by Linux `perf`, it occupies 28% of execution time.
We tighten the hottest loop in the above function. We create the super fast path for non escaping case.
And add " and \ cases (since including " in the string is common). Then we fallback to the slow case.
It improves the performance 5.5% in Kraken json-stringify-tinderbox in MBP.
Performance result in my MBP (dandelion).
Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc()
between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the
jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times
with 95% confidence intervals in milliseconds.
baseline patched
json-stringify-tinderbox 29.243+-0.241 ^ 27.701+-0.235 ^ definitely 1.0557x faster
<arithmetic> 29.243+-0.241 ^ 27.701+-0.235 ^ definitely 1.0557x faster
Performance result in my Linux laptop (hanayamata).
Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc()
between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the
jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times
with 95% confidence intervals in milliseconds.
baseline patched
json-stringify-tinderbox 26.711+-0.475 ^ 25.255+-0.034 ^ definitely 1.0577x faster
<arithmetic> 26.711+-0.475 ^ 25.255+-0.034 ^ definitely 1.0577x faster
* wtf/text/StringBuilder.cpp:
(WTF::appendQuotedJSONStringInternalSlow):
(WTF::appendQuotedJSONStringInternal):
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (209857 => 209858)
--- trunk/Source/WTF/ChangeLog 2016-12-15 08:19:47 UTC (rev 209857)
+++ trunk/Source/WTF/ChangeLog 2016-12-15 10:28:55 UTC (rev 209858)
@@ -1,3 +1,48 @@
+2016-12-15 Yusuke Suzuki <[email protected]>
+
+ [JSC] Optimize Kraken stringify
+ https://bugs.webkit.org/show_bug.cgi?id=165857
+
+ Reviewed by Darin Adler.
+
+ Kraken json-stringify-tinderbox performance heavily relies on StringBuilder::appendQuotedJSONString.
+ According to the result produced by Linux `perf`, it occupies 28% of execution time.
+
+ We tighten the hottest loop in the above function. We create the super fast path for non escaping case.
+ And add " and \ cases (since including " in the string is common). Then we fallback to the slow case.
+
+ It improves the performance 5.5% in Kraken json-stringify-tinderbox in MBP.
+
+ Performance result in my MBP (dandelion).
+
+ Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc()
+ between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the
+ jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times
+ with 95% confidence intervals in milliseconds.
+
+ baseline patched
+
+ json-stringify-tinderbox 29.243+-0.241 ^ 27.701+-0.235 ^ definitely 1.0557x faster
+
+ <arithmetic> 29.243+-0.241 ^ 27.701+-0.235 ^ definitely 1.0557x faster
+
+ Performance result in my Linux laptop (hanayamata).
+
+ Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc()
+ between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the
+ jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times
+ with 95% confidence intervals in milliseconds.
+
+ baseline patched
+
+ json-stringify-tinderbox 26.711+-0.475 ^ 25.255+-0.034 ^ definitely 1.0577x faster
+
+ <arithmetic> 26.711+-0.475 ^ 25.255+-0.034 ^ definitely 1.0577x faster
+
+ * wtf/text/StringBuilder.cpp:
+ (WTF::appendQuotedJSONStringInternalSlow):
+ (WTF::appendQuotedJSONStringInternal):
+
2016-12-14 Commit Queue <[email protected]>
Unreviewed, rolling out r209795.
Modified: trunk/Source/WTF/wtf/text/StringBuilder.cpp (209857 => 209858)
--- trunk/Source/WTF/wtf/text/StringBuilder.cpp 2016-12-15 08:19:47 UTC (rev 209857)
+++ trunk/Source/WTF/wtf/text/StringBuilder.cpp 2016-12-15 10:28:55 UTC (rev 209858)
@@ -386,46 +386,58 @@
}
template <typename OutputCharacterType, typename InputCharacterType>
+static void appendQuotedJSONStringInternalSlow(OutputCharacterType*& output, const InputCharacterType character)
+{
+ switch (character) {
+ case '\t':
+ *output++ = '\\';
+ *output++ = 't';
+ break;
+ case '\r':
+ *output++ = '\\';
+ *output++ = 'r';
+ break;
+ case '\n':
+ *output++ = '\\';
+ *output++ = 'n';
+ break;
+ case '\f':
+ *output++ = '\\';
+ *output++ = 'f';
+ break;
+ case '\b':
+ *output++ = '\\';
+ *output++ = 'b';
+ break;
+ default:
+ ASSERT(!(character & 0xFF00));
+ *output++ = '\\';
+ *output++ = 'u';
+ *output++ = '0';
+ *output++ = '0';
+ *output++ = upperNibbleToLowercaseASCIIHexDigit(character);
+ *output++ = lowerNibbleToLowercaseASCIIHexDigit(character);
+ break;
+ }
+}
+
+template <typename OutputCharacterType, typename InputCharacterType>
static void appendQuotedJSONStringInternal(OutputCharacterType*& output, const InputCharacterType* input, unsigned length)
{
for (const InputCharacterType* end = input + length; input != end; ++input) {
- if (LIKELY(*input > 0x1F)) {
- if (*input == '"' || *input == '\\')
- *output++ = '\\';
- *output++ = *input;
+ const InputCharacterType character = *input;
+ if (LIKELY(character != '"' && character != '\\' && character > 0x1F)) {
+ *output++ = character;
continue;
}
- switch (*input) {
- case '\t':
+
+ if (character == '"' || character == '\\') {
*output++ = '\\';
- *output++ = 't';
- break;
- case '\r':
- *output++ = '\\';
- *output++ = 'r';
- break;
- case '\n':
- *output++ = '\\';
- *output++ = 'n';
- break;
- case '\f':
- *output++ = '\\';
- *output++ = 'f';
- break;
- case '\b':
- *output++ = '\\';
- *output++ = 'b';
- break;
- default:
- ASSERT((*input & 0xFF00) == 0);
- *output++ = '\\';
- *output++ = 'u';
- *output++ = '0';
- *output++ = '0';
- *output++ = upperNibbleToLowercaseASCIIHexDigit(*input);
- *output++ = lowerNibbleToLowercaseASCIIHexDigit(*input);
- break;
+ *output++ = character;
+ continue;
}
+
+ appendQuotedJSONStringInternalSlow(output, character);
}
}
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