Status: New
Owner: ----
New issue 1510 by [email protected]: Missing range analysis for logical shift
http://code.google.com/p/v8/issues/detail?id=1510
Generated code consuming >>> is less efficient because the range analysis
does nothing special and fails to see the result is often a Smi.
Conservative range arithmetic:
Shr([a, b], unknown-shift-count)
= [0, b] if a >= 0
= [a, 0x7fffffff] if a < 0
For known shift counts:
Shr([a, b], 0) = [a, b]
Shr([a, b], k) = [a>>>k, b>>>k] if a>=0
Shr([a, b], k) = [0, 0xffffffff >>> k] if a<0
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