In constructing the transfer between loop copies, we need to merge the backedges from all the previous copies of the given loop. The control reduction will work out which ones are really reachable.
R=mstarzinger@chromium.org
BUG=
Review URL: https://codereview.chromium.org/1004993004
Cr-Commit-Position: refs/heads/master@{#27246}
Along the way:
- Thread isolate parameter explicitly through code that used to
rely on getting it from the zone.
- Canonicalize the parameter position of isolate and zone for
affected code
- Change Hydrogen New<> instruction templates to automatically
pass isolate
R=mstarzinger@chromium.org
LOG=N
Review URL: https://codereview.chromium.org/868883002
Cr-Commit-Position: refs/heads/master@{#26252}
