PartialStore is a PMOUseKind that is a vestigal remnant of Definite Init in the
PMO source. This can be seen by noting that in Definite Init, PartialStore is
how Definite Init diagnoses partially initialized values and errors. In contrast
in PMO the semantics of PartialStore are:
1. It can only be produced if we have a raw store use or a copy_addr.
2. We allow for the use to provide an available value just like if it was an
assign or an init.
3. We ignore it for the purposes of removing store only allocations since by
itself without ownership, stores (and stores from exploded copy_addr) do not
effect ownership in any way.
Rather than keeping this around, in this commit I review it since it doesn't
provide any additional value or [init] or [assign]. Functionally there should be
no change.
TLDR: This does not eliminate the struct/tuple flat namespace from Predictable
Mem Opts. Just the tuple specific flat namespace code from PMOMemoryUseCollector
that we were computing and then throwing away. I explain below in more detail.
First note that this is cruft from when def-init and pmo were one pass. What we
were doing here was maintaing a flattened tuple namespace while we were
collecting uses in PMOMemoryUseCollector. We never actually used them for
anything since we recomputed this information including information about
structs in PMO itself! So this information was truly completely dead.
This commit removes that and related logic and from a maintenance standpoint
makes PMOMemoryUseCollector a simple visitor that doesn't have any real special
logic in it beyond the tuple scalarization.
Just a part of a series of small cleanups I found over the break in PMO that I
am landing in preparation for landing patches that fix PMO for ownership.
These are vestigal remnants of the code when it needed to support DI and
PredMemOpts. Since both of the passes have been split, these are now dead in
PMO. So eliminate them.
I am going to DI and predictable mem opts have been split for a long time and
their subroutines aren't going to be joined in the future... so replace the DI
prefixes in pred-mem-opts impl with PMO and rename DIMemoryUseCollector =>
PMOUseCollector.
Been sitting on this for a long time... just happy to get it in.
