Reformatting everything now that we have `llvm` namespaces. I've
separated this from the main commit to help manage merge-conflicts and
for making it a bit easier to read the mega-patch.
This is phase-1 of switching from llvm::Optional to std::optional in the
next rebranch. llvm::Optional was removed from upstream LLVM, so we need
to migrate off rather soon. On Darwin, std::optional, and llvm::Optional
have the same layout, so we don't need to be as concerned about ABI
beyond the name mangling. `llvm::Optional` is only returned from one
function in
```
getStandardTypeSubst(StringRef TypeName,
bool allowConcurrencyManglings);
```
It's the return value, so it should not impact the mangling of the
function, and the layout is the same as `std::optional`, so it should be
mostly okay. This function doesn't appear to have users, and the ABI was
already broken 2 years ago for concurrency and no one seemed to notice
so this should be "okay".
I'm doing the migration incrementally so that folks working on main can
cherry-pick back to the release/5.9 branch. Once 5.9 is done and locked
away, then we can go through and finish the replacement. Since `None`
and `Optional` show up in contexts where they are not `llvm::None` and
`llvm::Optional`, I'm preparing the work now by going through and
removing the namespace unwrapping and making the `llvm` namespace
explicit. This should make it fairly mechanical to go through and
replace llvm::Optional with std::optional, and llvm::None with
std::nullopt. It's also a change that can be brought onto the
release/5.9 with minimal impact. This should be an NFC change.
NOTE: debug_value [moved] appearing in the source code implies a _move was
used. So this will not effect current stable swift code.
This is just a first version of this that I am using to commit/bring up tests
for IRGen supporting a full dataflow version of this patch.
Big picture is that there is a bunch of work that is done in the LLVM level in
the coroutine splitter to work around communicating live variables in the
various coroutine func-lets. This logic is all done with debug.declare and we
would need to update that logic in the coroutine splitter to handle
debug.addr. Rather than do this, after some conversation, AdrianP and I realized
that we could get the same effect of a debug.declare by just redeclaring the
current live set of debug_value after each possible coroutine funclet start. To
do this in full generality, we need a full dataflow but just to bring this up we
initially perform a dominance propagation algorithm of the following sort:
1. We walk the CFG along successors. By doing this we guarantee that we visit
blocks after their dominators.
2. When we visit a block, we walk the block from start->end. During this walk:
a. We grab a new block state from the centralized block->blockState map. This
state is a [SILDebugVariable : DebugValueInst].
b. If we see a debug_value, we map blockState[debug_value.getDbgVar()] =
debug_value. This ensures that when we get to the bottom of the block, we
have pairs of SILDebugVariable + last debug_value on it.
c. If we see any coroutine funclet boundaries, we clone the current tracked
set of our block state and then walk up the dom tree dumping in each block
any debug_value with a SILDebugVariable that we have not already
dumped. This is maintained by using a visited set of SILDebugVariable for
each funclet boundary.
The end result is that at the beginning of each funclet we will basically
declare the debug info for an addr.
This is insufficient of course for moves that are in conditional control flow,
e.x.:
```
let x = Klass()
if boolValue {
await asyncCall()
let _ = _move(x)
}
```
but this at least lets me begin to write tests for this in lldb using straight
line code and work out the rest of the issues in CodeGen using those tests.
Otherwise they will never compare the same. Also restore the test that was
updated for the previous commit to its old state. I did this to ensure that each
commit would compile successfully and so that I could show the test associated
with this commit.
