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Bug 775801 - LambdaIsGetElem should optimize based on JSOP_GETALIASEDVAR, not JSOP_NAME (r=dvander)

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This commit is contained in:
Luke Wagner 2012-07-20 16:17:24 -07:00
parent 7cd67d1fd5
commit 7260f3fa4e
2 changed files with 19 additions and 18 deletions
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8
js/src/jit-test/tests/basic/testBug775801.js Normal file
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@ -0,0 +1,8 @@
function f() {
var x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15,x16,x17,x18,x19,x20;
var b = {a:'ponies'};
eval('');
return function(e) { return b[e] }
}
assertEq("aaa".replace(/a/g, f()), "poniesponiesponies");

29
js/src/jsstr.cpp
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@ -2213,26 +2213,19 @@ LambdaIsGetElem(JSObject &lambda, JSContext *cx)
JSScript *script = fun->script();
jsbytecode *pc = script->code;
/* Look for an access to 'b' in the enclosing scope. */
if (JSOp(*pc) != JSOP_NAME)
return NULL;
PropertyName *bname;
GET_NAME_FROM_BYTECODE(script, pc, 0, bname);
pc += JSOP_NAME_LENGTH;
/*
* Do a conservative search for 'b' in the enclosing scope. Avoid using a
* real name lookup since this can trigger observable effects.
* JSOP_GETALIASEDVAR tells us exactly where to find the base object 'b'.
* Rule out the (unlikely) possibility of a heavyweight function since it
* would make our scope walk off by 1.
*/
Value b;
RootedObject scope(cx, cx->stack.currentScriptedScopeChain());
while (true) {
if (!scope->isCall() && !scope->isBlock())
return NULL;
if (HasDataProperty(cx, scope, bname, &b))
break;
scope = &scope->asScope().enclosingScope();
}
if (JSOp(*pc) != JSOP_GETALIASEDVAR || fun->isHeavyweight())
return NULL;
ScopeCoordinate sc(pc);
ScopeObject *scope = &fun->environment()->asScope();
for (unsigned i = 0; i < sc.hops; ++i)
scope = &scope->enclosingScope().asScope();
Value b = scope->aliasedVar(sc);
pc += JSOP_GETALIASEDVAR_LENGTH;
/* Look for 'a' to be the lambda's first argument. */
if (JSOp(*pc) != JSOP_GETARG || GET_SLOTNO(pc) != 0)