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Bug 646599 - Constant folding should happen before deciding whether to turn obj[A] into obj.A. r=Waldo

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This commit is contained in:
Tom Schuster 2012-07-21 13:05:07 +02:00
parent 334d4312d7
commit d81f8f9714
2 changed files with 41 additions and 7 deletions
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25
js/src/frontend/Parser.cpp
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@ -57,6 +57,8 @@
#include "frontend/ParseMaps-inl.h"
#include "frontend/ParseNode-inl.h"
#include "frontend/TreeContext-inl.h"
#include "vm/NumericConversions.h"
#include "vm/RegExpObject-inl.h"
using namespace js;
@ -5805,10 +5807,17 @@ Parser::memberExpr(bool allowCallSyntax)
TokenPtr begin = lhs->pn_pos.begin, end = tokenStream.currentToken().pos.end;
/*
* Optimize property name lookups. If the name is a PropertyName,
* Do folding so we don't have roundtrip changes for cases like:
* function (obj) { return obj["a" + "b"] }
*/
if (foldConstants && !FoldConstants(context, propExpr, this))
return NULL;
/*
* Optimize property name lookups. If the name is a PropertyName,
* then make a name-based node so the emitter will use a name-based
* bytecode. Otherwise make a node using the property expression
* by value. If the node is a string containing an index, convert
* bytecode. Otherwise make a node using the property expression
* by value. If the node is a string containing an index, convert
* it to a number to save work later.
*/
uint32_t index;
@ -5823,11 +5832,13 @@ Parser::memberExpr(bool allowCallSyntax)
name = atom->asPropertyName();
}
} else if (propExpr->isKind(PNK_NUMBER)) {
JSAtom *atom = ToAtom(context, NumberValue(propExpr->pn_dval));
if (!atom)
return NULL;
if (!atom->isIndex(&index))
double number = propExpr->pn_dval;
if (number != ToUint32(number)) {
JSAtom *atom = ToAtom(context, DoubleValue(number));
if (!atom)
return NULL;
name = atom->asPropertyName();
}
}
if (name)

23
js/src/jit-test/tests/basic/testFoldPropertyAccess.js Normal file
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@ -0,0 +1,23 @@
var cases = [
function (obj) {
return obj["ab"];
},
function (obj) {
return obj["a" + "b"];
},
function (obj) {
return obj[0 ? "cd" : "ab"];
},
function (obj) {
return obj[true ? "ab" : "cd"];
},
function (obj) {
return obj[(1 + 0) ? "ab" : "cd"];
}
]
for (var i = 0; i < cases.length; i++) {
assertEq(cases[i]({ab: 42}), 42);
assertEq(cases[i]({cd: 120}), undefined);
}