First steps towards using constant values in lowering.
For now, we reuse the regular instruction lowering to lower constants.
This mostly works, because we don't actually need an `llvm::Function` or
a current basic block when lowering a constant most of the time.
However, a special case is needed for lowering aggregate value constants
because they would otherwise create a stack alloca to store the
constant. Separate constant lowering code will be added in a future
change to clean this up.
When lowering a constant initializing expression, the result is a value
of the destination type, rather than code to initialize the destination,
so a separate copy step is required when finishing initialization from a
constant for a type that uses in-place initialization. Handling this
required extending `ReturnExpr` to track its destination location.
We currently often create non-constant `*_access` SemIR instructions
that are only used by constant `*_init` instructions. These cause
lowering to leave behind `getelementptr` instructions in the lowered IR
that are now unused. It should be possible to detect this case and avoid
producing these instructions, or to produce them lazily, but for now
we're just leaving them around for LLVM to clean up.
Move completeness check to the point where the function is defined or
first called. This means we also defer deciding whether the function has
a return slot until that point. Instead of storing a return slot per
function, store the location of the return storage, which may or may not
be used, and compute and store a separate flag saying whether to use it
at the point of first use or definition.
This is the final piece in supporting simple `Make` functions in classes
as a replacement for constructors.
This was previously discussed at
https://discord.com/channels/655572317891461132/655578254970716160/1209975051588210729.
I'm initiating this mainly because we typically use "id" suffixes to
indicate an `IdBase` being passed around and the non-id suffix of
`parse_node` suggests at it carrying more data than it actually does.
There used to be more reason for avoiding `node_id` because
`SemIR::InstId` used to be named `NodeId`, but that's no longer
necessary. As a consequence, I'd like to rename `parse_node` to more
precisely reflect its type.
In full, this is doing:
```
parse_node_kind -> node_kind
parse_node -> node_id
ParseNodeCategory -> NodeCategory
ParseNodeKind -> NodeKind
ParseNode -> NodeId
```
This is primarily in check and sem_ir, but with some `parse_node_kind`
references in parse too.
Pluralization is consistent with name forms on both sides, so that
wasn't part of my replacements.
Note we may also want to do this with NameId, maybe some other things,
but the TypeId use is pretty broad and repetitive -- I thought I'd start
with it first.
This required adding a few headers that were found transitively before,
but not too many. This is sadly a fairly manual process of opening every
file in my IDE, but I think I got everything in `//common` and
`//toolchain`.
There are a few cases where technically we don't need `foo.h` to be
included into `foo.cpp`, but I've forced those to stay with a pragma.
I've tried to catch the places where we can cut deps in Bazel as well,
but not sure I got all of those.
I had been noticing these in other PRs and it seemed better to isolate
the change.
The parse nodes are still tracked as part of the same value store
interface in order to ensure parity, but they're split out from Inst
itself in order to reduce the size of Inst -- the expectation is that
they don't need to be passed around quite as much.
This change doesn't actually reduce the passing very much, although
there are hints of it: AddInstAndPush doesn't typically need a separate
parse node from the one on the Inst itself, for example. In a couple
spots I changed code to rely a little more on the InstId until the
ParseNode is needed, but it's very low hanging fruit where done. I think
convert could do more to not eagerly fetch the parse node before its
use, but more cleanup felt it would be easier to handle separately. I'm
currently viewing this as making such cleanup _possible_ rather than
executing on it up-front.
But also, I want to make sure there's a consensus to head in this
direction before pulling the trigger. We speculated that this would
result in the parse node being passed around less, and I do think that's
the case, although it's a bit fuzzy in the change.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This involves a number of supporting changes:
* The `parse_node;` member of instruction types may now have any type
derived from `Parse::NodeId` and is no longer required to have that
exact type.
* `Parse::Node::Invalid` is now a singleton object of a separate type
that is convertible to `Parse::NodeId` and its descendants. This
replaces the `Invalid` member of its descendants, and avoids having to
write long `NodeIdOneOf<...>` types when initializing variables to
invalid.
* `IndexBase` now allows `==` and `!=` comparisons between its derived
classes and types that are convertible to those types.
* A number of functions in the check stage have been changed to preserve
more type information instead of using `Parse::NodeId`.
* `NodeIdForKind<K>` (also known as `KId`) now has a `Kind` member so it
may be used to declare `NodeIdOneOf<T, U>` types without #including
`parse/typed_nodes.h`.
* `NodeIdForKind<K>` (also known as `KId`) may be implicitly converted
to `NodeIdOneOf<T, U>` if `T::Kind == K` or `U::Kind == K` (executing a
TODO).
Many of the `parse_node` members were not converted since they would
have required more extensive changes. They have been marked with "TODO"
comments.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Most of the calls to `StringifyType` already passed `true` for
`in_type_context`. Checking the rest, I found that every one of them was
already sufficiently clear that they were printing a type, or could be
made so with a very small change to the diagnostic text.
Implement toolchain support for `returned var` and `return var`.
- Modeled `returned` in the parse tree as a `ReturnedSpecifier`
appearing after the `VariableIntroducer`.
- Modeled `return var` in the parse tree as a `ReturnVarSpecifier`
appearing after the `ReturnStatementStart`.
- Factored out the implementation of `return` statement and `returned
var` handling in check into a new `return.{h,cpp}`. The parse nodes
themselves are still handled in `handle_*.cpp`. This allows easy code
reuse between `return` and `returned var`.
Richard Smith
Jon Ross-Perkins
Chandler Carruth
josh11bandRichard Smith