The DFG JIT may speculate that a value is double if it has no evidence that it is an integer, but it has evidence that it should be a number. But doing so means that integers will turn into doubles. Doubles are less efficient than integers in certain cases, such as for performing GetByVal accesses. The DFG JIT should have some way of undoing double speculation when jumping to non-speculative code - that is, attempting to convert doubles back to integers so as to prevent the non-speculative code does not have to take even deeper slow paths when doing array accesses.
Created attachment 102284 [details]
Comment on attachment 102284 [details]
Clearing flags on attachment: 102284
Committed r92024: <http://trac.webkit.org/changeset/92024>
All reviewed patches have been landed. Closing bug.