Type annotations for instruction operands are omitted, e.g.
```
%3 = struct $S(%1, %2)
```
Operand types are redundant anyway and were only used for sanity checking in the SIL parser.
But: operand types _are_ printed if the definition of the operand value was not printed yet.
This happens:
* if the block with the definition appears after the block where the operand's instruction is located
* if a block or instruction is printed in isolation, e.g. in a debugger
The old behavior can be restored with `-Xllvm -sil-print-types`.
This option is added to many existing test files which check for operand types in their check-lines.
Types that have "value semantics" should not have lexical lifetimes.
Value types are not expected to have custom deinits. Are not expected to
expose unsafe interior pointers. And cannot have weak references because
they are structs. Therefore, deinitialization barriers are irrelevant.
rdar://107076869
This is all relatively nicely abstracted, which is not to say that
it didn't take an awful lot of plumbing to get it to work. The basic
problem here is inherent: we need to do component-specific setup and
teardown, and unfortunately in the current representation we have to
do that with separate loops and without any dominance relationships.
(This is the same thing preventing us from doing borrows in the
general case.) The result is that the general case of result emission
is to emit every element of the expansion into a temporary tuple
(requiring a pack loop before the call to initialize the pack), then
process those elements in the body of a second pack loop after the
call. And that's terrible enough that we really have to do the work
to try to avoid it, which makes all the APIs more complicated.
Anyway, most of the way through the basic plumbing for variadic
generics now. Next is reabstraction, I think, which I hope will
mostly mean fixing bugs in the infrastructure I've already written.
This required quite a bit of infrastructure for emitting this kind of
tuple expression, although I'm not going to claim they really work yet;
in particular, I know the RValue constructor is going to try to explode
them, which it really shouldn't.
It also doesn't include the caller side of returns, for which I'll need
to teach ResultPlan to do the new abstraction-pattern walk. But that's
next.
