Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
We do keep the fragment part of the expression as it is important
to identify fragments separately.
A variable with less fragments should be considered a superset of
variables with more fragments, but that would require to change a
lot of code.
For years, optimizer engineers have been hitting a common bug caused by passes
assuming all SILValues have a parent function only to be surprised by SILUndef.
Generally we see SILUndef not that often so we see this come up later in
testing. This patch eliminates that problem by making SILUndef uniqued at the
function level instead of the module level. This ensures that it makes sense for
SILUndef to have a parent function, eliminating this possibility since we can
define an API to get its parent function.
rdar://123484595
I discovered when working with improving the debug output of the move only
address checker that I had a need for lightweight thing like
DebugVarCarryingInst but that only could vend a VarDecl (unlike
DebugVarCarryingInst which also can vend a SILDebugVariable). As an example,
this lets one write a high level API that uses the standard API to loop over a
bunch of instructions all that vend a VarDecl and construct a stringified path
component list.
rdar://105293841
The overall flow of the pass is:
1. We walk over the blocks summarizing the debug info instruction the blocks gen
as well as whether or not the block had an async funclet edge with in it.
2. We then perform a simple forward iterative optimistic dataflow using
intersection at merge points. At points where we find after merging that we have
a conflict and thus need to stop propagation, we insert a debug_value undef.
3. We then walk the CFG again visiting only blocks that we know had async
funclet edges. We then walk each said block from top to bottom starting with the
propagating gen information and updating as we go, dumping the current set of
debug_info we are tracking after each coroutine funclet boundary.
rdar://85020571
