[JSC] ResolveNode can't always skip the extra move #10853
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kmiller68
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| let b=((a=b),{t(){b}}) | ||
| }catch{ | ||
| } | ||
| a._ |
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To verify I understand the bug correctly, without this change (and with the other change), a is JSValue() here and not the original value?
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Yes, that's right. We evaluate a = b (= JSValue()) then check_tdz throws, but we already assigned
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https://bugs.webkit.org/show_bug.cgi?id=253142 rdar://106076478 Reviewed by Keith Miller. In http://commits.webkit.org/260555@main I landed an optimization avoid the extra move in ResolveNode. However, that's not valid when we actually need the TDZ check. If the check fails, we throw an exception, but we already wrote to the destination. As a compromise, we still avoid the move unless we actually need the TDZ check. * JSTests/stress/tdz-check-catch-read.js: Added. (f): * Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp: (JSC::ResolveNode::emitBytecode): Canonical link: https://commits.webkit.org/261006@main
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Committed 261006@main (e7b74be): https://commits.webkit.org/261006@main Reviewed commits have been landed. Closing PR #10853 and removing active labels. |
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