Fix optimized element access that incorrectly reports that the instance has no such property#841
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@Yongqu @ianwjhalliday Reimplemented this so that we only do extra work when we've discovered that no PropertyRecord exists for the given property name. Seems to get rid of perf regressions. |
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Ping @Yongqu @ianwjhalliday |
| { | ||
| // If the instance doesn't have the property, typeof result is "undefined". | ||
| threadContext->CheckAndResetImplicitCallAccessorFlag(); | ||
| threadContext->AddImplicitCallFlags(savedImplicitCallFlags); |
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how do we know there is implicit call?
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I think this is conservative; I don't know why it was originally added.
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…optimization requires a prototype chain walk to confirm that the property being looked for can't be found on an object such as a CEO that may use names unknown to the JS engine, or that, like a proxy, may require that the lookup be done regardless. For now the prototype walk is done on every attempted access where no property record exists for the index name. This could be optimized with a scheme similar to the one we use for non-writable properties in the prototype chain, but I'd like to see a needful use case before I saddle us with another registration mechanism. Benchmarks are flat.
chakrabot
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…at the instance has no such property Merge pull request #841 from pleath:isjsnative2 Reimplement shortcut in element access on unknown property name. The optimization requires a prototype chain walk to confirm that the property being looked for can't be found on an object such as a CEO that may use names unknown to the JS engine, or that, like a proxy, may require that the lookup be done regardless. For now the prototype walk is done on every attempted access where no property record exists for the index name. This could be optimized with a scheme similar to the one we use for non-writable properties in the prototype chain, but I'd like to see a needful use case before I saddle us with another registration mechanism. Benchmarks are flat.
chakrabot
pushed a commit
that referenced
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May 4, 2016
…ly reports that the instance has no such property Merge pull request #841 from pleath:isjsnative2 Reimplement shortcut in element access on unknown property name. The optimization requires a prototype chain walk to confirm that the property being looked for can't be found on an object such as a CEO that may use names unknown to the JS engine, or that, like a proxy, may require that the lookup be done regardless. For now the prototype walk is done on every attempted access where no property record exists for the index name. This could be optimized with a scheme similar to the one we use for non-writable properties in the prototype chain, but I'd like to see a needful use case before I saddle us with another registration mechanism. Benchmarks are flat.
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Reimplement shortcut in element access on unknown property name. The optimization requires a prototype chain walk to confirm that the property being looked for can't be found on an object such as a CEO that may use names unknown to the JS engine, or that, like a proxy, may require that the lookup be done regardless. For now the prototype walk is done on every attempted access where no property record exists for the index name. This could be optimized with a scheme similar to the one we use for non-writable properties in the prototype chain, but I'd like to see a needful use case before I saddle us with another registration mechanism. Benchmarks are flat.