`AddDefaultValue` doesn't quite capture the intended semantics; it
should typically be replaced with an actual value when dealing with
control flows. Trying to indicate the "assign later" with
`AddPlaceholder`, mirroring `AddPlaceholderInst`.
Shifting the `protected` functionality on `BlockValueStore` so that it's
not providing functions just for `InstBlockStore` to use. Also hoping
that seeing the comments next to the function name makes them easier to
understand, whereas `using` buries that a little.
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Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This in particular uses free functions because it's likely to end up
more consistent with types (versus a wrapper object for InstStore).
Note, this is unlikely to have a performance impact, but if it does, we
can look into related approaches (and we've already discussed using
LTO).
Renames `PendingBlock::AddInst` to `PendingBlock::Add` because
`MakeElementAccessInst` expects the matching name to exist.
context.cpp is getting large, so I'm looking at a few ways to cut out
clusters of functions. This felt like a logical cluster of functions to
move to their own file.
Note this doesn't touch the implementation at all, beyond what's needed
to change from `Context` members to context args.