[move-function] Implement support for checking in defers #40775
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…lready added to the address test suites.
…I need to store them. Specifically, I need to perform the initial gathering of uses for all addresses at the same time so I can handle their closures all at the same time.
…t_aliasable defer parameters to out parameters after move analysis.
Returns true if this SILFunction must be a defer. NOTE: This may return false for defer statements that have been deserialized without a DeclContext. This means that this is guaranteed to be correct for SILFunctions in Raw SIL that were not deserialized as canonical. Thus one can use it for diagnostics.
This dataflow is used to determine if a closure/defer use of a value as an
inout_aliasable value is consume inclusive-or liveness requiring use in a
caller. This information is used to determine if a closure invocation or defer
at the source level acts as a use after move in the source level caller of a
moved var or if the moved var is reinited in the function.
This is done by:
1. Classifying all uses of the inout_aliasable argument as either init, consume,
use.
2. We then perform two separate dataflows that summarize the effect of the
closure upon the specific address argument:
a. First for each individual use, we walk upwards along predecessors to the
beginning of the function stopping at consumes, inits, and other uses. If
our dataflow eventually reaches the entrance block, then we know that we
have a use that should be an error. If all uses are blocked by a consume,
init, or other use then we know that if our operand was moved in a caller,
the address is not used after the move at least in this callee.
b. With that in hand, we then perform a similar dataflow for each individual
consume operation except that we only stop at init blocks and other
consume blocks. This leaves us with a set of consuming operations of the
address that can be considered to be consume up out of the callee. We then
make sure that these consumes form a post dominating set of upon the
address or bail. If we bail, we do not handle the move in the caller
causing us to emit an unhandled move error later after all diagnostics
have run.
After performing both of these dataflows, our caller function can use our
outputs to emit an error if we had a use and a move is live in the caller or
create a new callee where our address argument is converted from an
inout_aliasable parameter to an out parameter.
This converts a set of closure inout_aliasable arguments to be out arguments and fixes up the initial post dominating consume set of these arguments since we are hoisting the destroy out of the cloned closure.
…o that we can test end<->end. Since this is the final in the series of commits, I also added a bunch of tests since now we have an end to end implementation that /can/ actually be tested.
gottesmm
commented
Jan 8, 2022
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NOTE: In the next commit in this PR, I change this to use the cloning logic. This was just a stop gap (that actually emits incorrect code due to the lack of conversion to the out parameter). So if one is reading commit by commit, check the next commit.
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@swift-ci test |
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I discovered that I forgot to implement the multi-block case in the caller of the closures. I have prepared another PR that fixes that and adds more tests in that area and some other areas as well (casts, etc). |
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This is an initial version of the code needed to handle reinitializing a variable in a defer. There is a bunch of boiler plate since:
I am doing some initial testing here and I am going to add more tests once this gets in tree.