Changeset 153245 in webkit for trunk/Source/JavaScriptCore/dfg/DFGUseKind.cpp

Timestamp:

Jul 24, 2013, 9:03:42 PM (12 years ago)

Author:

[email protected]

Message:

fourthTier: DFG should optimize identifier string equality
​https://bugs.webkit.org/show_bug.cgi?id=117920

Source/JavaScriptCore:

Reviewed by Sam Weinig.

This is a 20% speed-up for string equality comparisons when both strings are
identifiers.

This is important for two reasons:

1) Using strings as enumerations is an idiom. A great example is typeof. It

would be great if this performed better.

2) When I implement switch_string in the DFG, it would be great to optimize

the case where the switched-on value is an identifier. That would involve
a simple binary switch rather than a more complicated trie-switch over
characters.

• bytecode/SpeculatedType.cpp:

(JSC::dumpSpeculation):
(JSC::speculationToAbbreviatedString):
(JSC::speculationFromCell):

• bytecode/SpeculatedType.h:

(JSC):
(JSC::isStringIdentSpeculation):
(JSC::isStringSpeculation):

• dfg/DFGAbstractState.cpp:

(JSC::DFG::AbstractState::executeEffects):

• dfg/DFGFixupPhase.cpp:

(JSC::DFG::FixupPhase::fixupNode):

• dfg/DFGNode.h:

(JSC::DFG::Node::shouldSpeculateStringIdent):
(Node):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::compilePeepHoleBranch):
(JSC::DFG::SpeculativeJIT::compare):
(JSC::DFG::SpeculativeJIT::compileStrictEq):
(JSC::DFG::SpeculativeJIT::compileStringEquality):
(JSC::DFG::SpeculativeJIT::compileStringIdentEquality):
(DFG):
(JSC::DFG::SpeculativeJIT::speculateString):
(JSC::DFG::SpeculativeJIT::speculateStringIdentAndLoadStorage):
(JSC::DFG::SpeculativeJIT::speculateStringIdent):
(JSC::DFG::SpeculativeJIT::speculate):

• dfg/DFGSpeculativeJIT.h:

(SpeculativeJIT):

• dfg/DFGUseKind.cpp:

(WTF::printInternal):

• dfg/DFGUseKind.h:

(JSC::DFG::typeFilterFor):
(JSC::DFG::isCell):

LayoutTests:

Reviewed by Sam Weinig.

Add a benchmark for string equality where there is a long identifier, and
also add a benchmark for non-identifier string equality (since the previous
test for string equality was really identifier equality).

• fast/js/regress/script-tests/string-long-ident-equality.js: Added.

(foo):

• fast/js/regress/script-tests/string-var-equality.js: Added.

(addFoo):
(foo):

• fast/js/regress/string-long-ident-equality-expected.txt: Added.
• fast/js/regress/string-long-ident-equality.html: Added.
• fast/js/regress/string-var-equality-expected.txt: Added.
• fast/js/regress/string-var-equality.html: Added.

File:

• trunk/Source/JavaScriptCore/dfg/DFGUseKind.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/dfg/DFGUseKind.cpp

@@ -69 +69 @@
         out.print("ObjectOrOther");
         break;
+    case StringIdentUse:
+        out.print("StringIdent");
+        break;
     case StringUse:
         out.print("String");