Bug 210694
| Summary: | VM should have a bottomCellForSetLocal that is understood to be a true bottom value by the DFG | ||
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| Product: | WebKit | Reporter: | Keith Miller <keith_miller> |
| Component: | JavaScriptCore | Assignee: | Nobody <webkit-unassigned> |
| Status: | NEW | ||
| Severity: | Normal | ||
| Priority: | P2 | ||
| Version: | WebKit Nightly Build | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
Keith Miller
Right now we handle bottom values semantically needed for a SetLocal by vending a JSValue that roughly matches the predicted value for the non-bottom path. This comes up for op_iterator_open/next. Unfortunately, this still causes AI to be unhappy. If we had a constant cell that was understood by the DFG to be a bottom value (and presumably crashes whenever accessed), the DFG would generate better code for op_iterator_open/next.
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