If we have a and b both predicted number, then the following sequence: 1: ValueToNumber(a) 2: ValueToNumber(b) 3: ArithSub(@1, @2) should be turned into: 1: ValueToNumberPure(a) (skipped) 2: ValueToNumberPure(b) (skipped) 3: ArithSub(a, b) and hence we skip two moves and save a register.
<rdar://problem/10811325>
Created attachment 125590 [details] the patch
Created attachment 125721 [details] the patch
Landed in http://trac.webkit.org/changeset/106879