This CL re-purposes ValueEffect and Finish as delimiters for regions
that are scheduled atomically (renamed to BeginRegion, FinishRegion).
The BeginRegion node takes and produces an effect. For the uses that do
not care about the placement in the effect chain, it is ok to feed
graph->start() as an effect input.
The FinishRegion takes a value and an effect and produces a value and
an effect. It is important that any value or effect produced inside the
region is not used outside the region. The FinishRegion node is the only
way to smuggle an effect and a value out.
At the moment, this does not support control flow inside the region. Control flow would be hard.
During scheduling we do some sanity check, but the checks are not exhaustive. Here is what we check:
- the effect chain between begin and finish is linear (no splitting,
single effect input and output).
- any value produced is consumed by the FinishRegion node.
- no control flow outputs.
Review URL: https://codereview.chromium.org/1399423002
Cr-Commit-Position: refs/heads/master@{#31265}
This will allow exploration of possibilities like passing around buffer base and length.
BUG=None
TEST=test-multiple-return
LOG=N
R=mtrofin@chromium.org,titzer@chromium.org
Review URL: https://codereview.chromium.org/1391333003
Cr-Commit-Position: refs/heads/master@{#31184}
The three different concerns that the ControlReducer used to deal with
are now properly separated into
a.) DeadCodeElimination, which is a regular AdvancedReducer, that
propagates Dead via control edges,
b.) CommonOperatorReducer, which does strength reduction on common
operators (i.e. Branch, Phi, and friends), and
c.) GraphTrimming, which removes dead->live edges from the graph.
This will make it possible to run the DeadCodeElimination together with
other passes that actually introduce Dead nodes, i.e. typed lowering;
and it opens the door for general inlining without two stage fix point
iteration.
To make the DeadCodeElimination easier and more uniform, we basically
reverted the introduction of DeadValue and DeadEffect, and changed the
Dead operator to produce control, value and effect. Note however that
this is not a requirement, but merely a way to make dead propagation
easier and more uniform. We could always go back and decide to have
different Dead operators if some other change requires that.
Note that there are several additional opportunities for cleanup now,
i.e. OSR deconstruction could be a regular reducer now, and we don't
need to use TheHole as dead value marker in the GraphReducer. And we can
actually run the dead code elimination together with the other passes
instead of using separate passes over the graph. We will do this in
follow up CLs.
R=jarin@chromium.org, mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/1193833002
Cr-Commit-Position: refs/heads/master@{#29146}
This is needed in order to allow expansion of a throwing node into a
set of nodes that produce different effects for the successful and the
exceptional continuation.
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/1179543002
Cr-Commit-Position: refs/heads/master@{#28918}
This introduces a conservative prediction for each exception handler
whether it will locally catch an exception or re-throw it to outside
the code bondaries. It will allow for a more intuitive prediction of
whether an exception is considered "caught" or "uncaught".
R=bmeurer@chromium.org,yangguo@chromium.org
BUG=chromium:492522
LOG=N
Review URL: https://codereview.chromium.org/1158563008
Cr-Commit-Position: refs/heads/master@{#28681}
This way we don't need to connect (potentially) non-terminating loops
later during control reduction, which saves one forward pass over the
control graph. Long term we will move the trimming functionality of
the control reducer to the GraphReducer, and get rid of the Finish
method again.
As a bonus, this change also properly rewires Terminate, Throw and
Deoptimize during inlining.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/1155683004
Cr-Commit-Position: refs/heads/master@{#28625}
This simplifies the handling of the End node. Based on this CL we will
finally fix terminating every loop from the beginning (via Terminate
nodes) and fix inlining of Throw, Deoptimize and Terminate.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/1157023002
Cr-Commit-Position: refs/heads/master@{#28620}
This revives the Terminate operator and removes the weird Always
operator. As a first step we let the ControlReducer connect non
terminating loops via Terminate. The next step will be to change the
graph builder to insert Terminate nodes into every loop.
Review URL: https://codereview.chromium.org/1123213002
Cr-Commit-Position: refs/heads/master@{#28259}
This changes the IrOpcode::kThrow operator to have kNoThrow property,
which sounds unintuitive, but holds for our graphs. The operators is
used to indicate exceptional control flow out of the function, but in
itself does not throw, the throwing is done by a runtime call.
R=titzer@chromium.org
TEST=unittests/CommonOperatorTest/CommonSharedOperatorTest.Properties
Review URL: https://codereview.chromium.org/1046173002
Cr-Commit-Position: refs/heads/master@{#27541}
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}
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}
Branch can now have an optional hint, when the condition is
likely true or false, and if such a hint is present the other
basic block will be marked as deferred and placed at the end
of the function.
We currently use this feature for tagging int32/uint32 in
change lowering, and for load/store bounds checks in simplified
lowering.
TEST=cctest,unittests
R=dcarney@chromium.org
Review URL: https://codereview.chromium.org/642883003
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24802 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
