Comment #5 on issue 2513 by [email protected]: life benchmark slowness
http://code.google.com/p/v8/issues/detail?id=2513
I agree code size is a minor issue here, yeah. ?1:0 is small and especially
with gzip will be practically nothing since it repeats a lot.
But I am more worried about optimizations and interactions with other
optimizations. Replacing
i2 = i1 > 5;
with
i2 = i1 > 5 ? 1 : 0;
turns into a branch, doesn't it? And probably a poorly-predicted branch,
since this is for a general condition check, there's no reason to assume it
would always be in the same direction, so it is definitely not optimal
especially inside tight loops. Unless JS engines do something specific to
the pattern of
boolean ? 1 : 0
to remove the branch, but if we are talking about specific optimizations,
wouldn't it be simpler to specifically optimize
boolean | 0
(which has the same semantics in JS, is shorter, and doesn't imply a
branch)?
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