This enables function signature handles a case of self-recursion.
With this change we convert 11 @owned return value to "not owned", while
we convert 179 @owned parameter to @guanrateed.
rdar://24022375
More specifically, this handles a case of self-recursion.
With this change we convert 11 @owned return value to "not owned", while
we convert 179 @owned parameter to @guanrateed.
rdar://24022375
If a value is returned as @owned, we can move the epilogue retain
to the caller and convert the return value to @unowned. This gives
ARC optimizer more freedom to optimize the retain out on the caller's
side.
It appears that epilgue retains are harder to find than epilogue
releases. Most of the time they are not in the return block.
(1) Sometimes, they are in predecessors
(2) Sometimes they come from a call which returns an @owned return value.
This should be improved if we fix (1) and go bottom up.
(3) We do not handle exploded retain_value.
Currently, this catches a small number of opportunities.
We probably need to improve epilogue retain matcher if we are to handle
more cases.
This is part of rdar://24022375.
We also need some refactoring in the pass. e.g. break functions into smaller
functions. I will do with subsequent commit.
optimization.
We get some improvements on the # of parameters converted to guanrateed
from owned on the stdlib.
before
======
103 sil-function-signature-opts - Total owned args -> guaranteed args
after
======
118 sil-function-signature-opts - Total owned args -> guaranteed args
I see the following improvements by running benchmarks with and without this
change. Only difference >=1.05X
ErrorHandling 8154 7497 -657 -8.1% 1.09x
LinkedList 9973 9529 -444 -4.5% 1.05x
ObjectAllocation 239 222 -17 -7.1% 1.08x
RC4 23167 21993 -1174 -5.1% 1.05x (!)
This is part of rdar://22380547
