Before this commit all code relating to handling arguments in SILBasicBlock had
somewhere in the name BB. This is redundant given that the class's name is
already SILBasicBlock. This commit drops those names.
Some examples:
getBBArg() => getArgument()
BBArgList => ArgumentList
bbarg_begin() => args_begin()
I see some small performance improvements on a few benchmarks, but they
are likely to be due to noise.
The compilation pipeline is very epilogue release friendly at the moment,i.e.
we do not move the epilogue release of a function till very late in the pipeline.
Therefore, this global data flow sort of an overkill. I am going to change
the pass pipeline next so that we can move epilogue releases freely and the data
flow will become useful.
I do not see compilation time increase.
rdar://26446587
As promised, we separate the duty of moving retain release pairs with the
task of removing them. Now the task of moving retains and releases are in
Retain Release Code Motion committed in 51b1c0bc68.
The reason why this work is not needed is that ARC before any dataflow is
performed first summarizes the interesting instructions in all blocks. This
information is kept up to date by the ARC optimizer as it moves around
retains/releases.
Thus while performing dataflow, all we need to summarize are loops.
This speeds and reduces memory consumption of test cases with large
CFGs. The specific test case that spawned this fix was a large function
with many dictionary assignments:
public func func_0(dictIn : [String : MyClass]) -> [String : MyClass] {
var dictOut : [String : MyClass] = [:]
dictOut["key5000"] = dictIn["key500"]
dictOut["key5010"] = dictIn["key501"]
dictOut["key5020"] = dictIn["key502"]
dictOut["key5030"] = dictIn["key503"]
dictOut["key5040"] = dictIn["key504"]
...
}
This continued for 10k - 20k values.
This commit reduces the compile time by 2.5x and reduces the amount of
memory allocated by ARC by 2.6x (the memory allocation number includes
memory that is subsequently freed).
rdar://24350646
In all of the cases where this is being used, we already immediately perform an
unreachable if we find a TermKind::Invalid. So simplify the code and move it
into the conversion switch itself.
Previously, we relied on a quirk in the ARC optimizer so that we only
need to visit terminators top down. This simplified the dataflow. Sadly,
try_apply changes this since it is a terminator that provides a call
with the value, causing this assumption to break program correctness.
Now during the bottom up traversal, while performing the dataflow for a
block B, we (after visiting all instructions), visit B's predecessors to
see if any of them have a terminator that is a use or decrement. We then
take the most conservative result among all of the terminators and
advance the sequence accordingly.
I do not think that we can have multiple such predecessors today since all
interesting terminators can not have any critical edges to successors. Thus if
our block is a successor of any such block, it can not have any other
predecessors. This is mainly for future proofing if we decide that this is able
to be done in the future.
rdar://23853221
SR-102
(libraries now)
It has been generally agreed that we need to do this reorg, and now
seems like the perfect time. Some major pass reorganization is in the
works.
This does not have to be the final word on the matter. The consensus
among those working on the code is that it's much better than what we
had and a better starting point for future bike shedding.
Note that the previous organization was designed to allow separate
analysis and optimization libraries. It turns out this is an
artificial distinction and not an important goal.
