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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [JSC] implement async functions proposal"
href="https://bugs.webkit.org/show_bug.cgi?id=156147#c110">Comment # 110</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [JSC] implement async functions proposal"
href="https://bugs.webkit.org/show_bug.cgi?id=156147">bug 156147</a>
from <span class="vcard"><a class="email" href="mailto:sbarati@apple.com" title="Saam Barati <sbarati@apple.com>"> <span class="fn">Saam Barati</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=156147#c109">comment #109</a>)
<span class="quote">> Comment on <span class=""><a href="attachment.cgi?id=280020&action=diff" name="attach_280020" title="Patch">attachment 280020</a> <a href="attachment.cgi?id=280020&action=edit" title="Patch">[details]</a></span>
> Patch
>
> View in context:
> <a href="https://bugs.webkit.org/attachment.cgi?id=280020&action=review">https://bugs.webkit.org/attachment.cgi?id=280020&action=review</a>
>
> >> Source/JavaScriptCore/parser/Parser.cpp:624
> >> + if (UNLIKELY(m_runtimeFlags.isAsyncAwaitEnabled() && matchContextualKeyword(m_vm->propertyNames->async))) {
> >
> > There is a chance that this may be faster if the LHS and RHS were swapped because it might aid the register allocator.
> > Same with the similar compare elsewhere.
> > Is this what's slowing down the parser?
> > Have you tried making ASYNC a key word? That may be faster than checking the IDENT's StringImpl
>
> When executing `matchContextualKeyword(m_vm->propertyNames->async)`, it
> becomes `Identifier == Identifier` check and it should be pointer comparison
> because Identifier is already interned.</span >
I was just thinking that we may get almost identical codegen (or we would get slightly worse codegen but the machine's branch/indirect jump prediction would make up for it) for the 'switch' statement if we made ASYNC a keyword, and we wouldn't have this branch at each IDENT. But maybe this would cause slow downs elsewhere. I'm not sure. It's hard to predict without implementing it and measuring perf.</pre>
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