This adds a new ControlFlowOptimizer that - for now - recognizes chains
of Branches generated by the SwitchBuilder for a subset of javascript
switches into Switch nodes. Those Switch nodes are then lowered to
either table or lookup switches.
Also rename Case to IfValue (and introduce IfDefault) for consistency.
BUG=v8:3872
LOG=n
Review URL: https://codereview.chromium.org/931623002
Cr-Commit-Position: refs/heads/master@{#26691}
Adds Switch and Case operators to TurboFan and handles them
appropriately in instruction selection and code generation.
BUG=v8:3872
LOG=n
Review URL: https://codereview.chromium.org/892513003
Cr-Commit-Position: refs/heads/master@{#26515}
If a (pure) node has two or more uses, but there exists a path from the
common dominator of these uses to end, which does not contain a use,
then we split the node such that no unnecessary computation takes place.
Note however, that this only applies if the node cannot be hoisted out
of a loop.
BUG=v8:3864
LOG=n
R=jarin@chromium.org
Review URL: https://codereview.chromium.org/899433005
Cr-Commit-Position: refs/heads/master@{#26404}
Up until now we used a special Terminate node to artifically connect non
terminating loops to the End node, but this was kind of adhoc and didn't
work for the CFG. So without all kinds of weird hacks, the end block in
the CFG will not be connected to NTLs, which makes it impossible to
compute post dominance / control dependence in the current setting.
So instead of Terminate, we add a special Branch to NTLs, whose
condition is the special Always node, which corresponds to True, except
that it cannot be folded away. This way we don't need any special
machinery in the scheduler, since it's just a regular Branch.
R=titzer@chromium.org
Review URL: https://codereview.chromium.org/875263004
Cr-Commit-Position: refs/heads/master@{#26294}
