The main motivating change here is to prevent the creation of a fake
Decl object by the frontend in order to `@export()` a value.
Instead, `link.updateDeclExports` is renamed to `link.updateExports` and
accepts a tagged union which can be either a Decl.Index or a
InternPool.Index.
This logic is not correct in most cases. If any instruction needs to
operate with different semantics within `@TypeOf`, it should be made to
do so explicitly.
This broke a line in `std.mem`: I have opted to fix this in std for now,
since as far as I know it's not yet been discussed which operations (if
any) should be special-cased like this within `@TypeOf`.
Having simplified these functions in a previous commit, I felt inclined
to refactor their names, which were previously quite inconsistent. There
are now 4 "core" functions:
* `resolveValue` (previously `resolveMaybeUndefVal`) allows runtime-known and undef values.
* `resolveConstValue` (previously `resolveConstMaybeUndefVal`) allows undef but not runtime-known values.
* `resolveDefinedValue` (name unchanged) allows runtime-known values but not comptime-known undef.
* `resolveConstDefinedValue` (previously `resolveConstValue`) does not allow runtime-known or undef values.
You can see the inconsistencies in the old names here - sometimes we
specified "maybe undef", and sometimes we went the other way by
specifying "defined". With the new names, the most common function,
`resolveValue`, has the shortest name and does the most general thing,
and is the baseline that the other functions are adding logic to.
Some other functions were also renamed:
* `resolveMaybeUndefLazyVal` -> `resolveValueResolveLazy`
* `resolveMaybeUndefValIntable` -> `resolveValueIntable`
* `resolveMaybeUndefValAllowVariables` -> `resolveValueAllowVariables`
The main goal of this commit is to remove the `runtime_value` field from
`InternPool.Key` (and its associated representation), but there are a
few dominos. Specifically, this mostly eliminates the "maybe runtime"
concept from value resolution in Sema: so some resolution functions like
`resolveMaybeUndefValAllowVariablesMaybeRuntime` are gone. This required
a small change to struct/union/array initializers, to no longer
use `runtime_value` if a field was a `variable` - I'm not convinced this
case was even reachable, as `variable` should only ever exist as the
trivial value of a global runtime `var` decl.
Now, the only case in which a `Sema.resolveMaybeUndefVal`-esque function
can return the `variable` key is `resolveMaybeUndefValAllowVariables`,
which is directly called from `Sema.resolveInstValueAllowVariables`
(previously `Sema.resolveInstValue`), which is only used for resolving
the value of a Decl from `Module.semaDecl`.
While changing these functions, I also slightly reordered and
restructured some of them, and updated their doc comments.
This feature was made to work with the legacy incremental compilation
mechanism which is being reworked.
This commit regresses the ability to update files used with `@embedFile`
while the compiler is running.
In exchange, we get these benefits:
* The embedded file contents are copied directly into InternPool rather
than there being an extra allocation and memcpy.
* The EmbedFile struct, which represents a long-lived object, is made
more serialization friendly.
* Eliminate the creation and use of a Decl as an anonymous decl.
When implementing the new incremental compilation mechanism,
functionality will need to be added back for handling `@embedFile`.
Commit 5393e56500d499753dbc39704c0161b47d1e4d5c has a flaw pointed out
by @mlugg: the `ty` field of pointer values changes when comptime values
are pointer-casted. This commit introduces a new encoding which
additionally stores the "original pointer type" which is used to store
the alignment of the anonymous decl, and potentially other information
in the future such as section and pointer address space. However, this
new encoding is only used when the original pointer type differs from
the casted pointer type in a meaningful way.
I was able to make the LLVM backend and the C backend lower anonymous
decls with the appropriate alignment, however I will need some help
figuring out how to do this for the backends that lower anonymous decls
via src/codegen.zig and the wasm backend.
Instead of creating Module.Decl objects, directly create InternPool
pointer values using the anon_decl Addr encoding.
The LLVM backend needed code to notice the alignment of the pointer and
lower accordingly. The other backends likely need a similar change.
When analyzing the `validate_ref_ty` ZIR instruction, an assertion would
trip if the result type was a var args function argument. The fix is the
same as e6b73be870 - inline the logic of
`resolveType` and handle the case of var args.
Closes#17494
When analyzing the `as` ZIR instruction, an assertion would trip if the
result type was a var args function argument. The fix is simple: inline
a little bit of the `resolveType` logic into `analyzeAs` to make it
detect this situation - which it was already attempting to do.
Closes#16197
The following pairs of functions have been combined using the "advanced"
pattern used for other type queries:
* `Sema.fnHasRuntimeBits`, `Type.isFnOrHasRuntimeBits`
* `Sema.typeRequiresComptime`, `Type.comptimeOnly`
* add Module instances for each package's build.zig and attach it to the
dependencies.zig module with the hash digest hex string as the name.
* fix incorrectly skipping the wrong packages for creating
dependencies.zig
* a couple more renaming of "package" to "module"
Finish the work started in 4c4fb839972f66f55aa44fc0aca5f80b0608c731.
Now the compiler compiles again.
Wire up dependency tree fetching code in the CLI for `zig build`.
Everything is hooked up except for `createDependenciesModule` is not yet
implemented.
Instead of explicitly creating a `Module.Decl` object for each anonymous
declaration, each `InternPool.Index` value is implicitly understood to
be an anonymous declaration when encountered by backend codegen.
The memory management strategy for these anonymous decls then becomes to
garbage collect them along with standard InternPool garbage.
In the interest of a smooth transition, this commit only implements this
new scheme for string literals and leaves all the previous mechanisms in
place.
My previous change for reading / writing to unions at comptime did not handle
union field read/writes correctly in all cases. Previously, if a field was
written to a union, it would overwrite the entire value. This is problematic
when a field of a larger size is subsequently read, because the value would not
be long enough, causing a panic.
Additionally, the writing behaviour itself was incorrect. Writing to a field of
a packed or extern union should only overwrite the bits corresponding to that
field, allowing for memory reintepretation via field writes / reads.
I addressed these problems as follows:
Add the concept of a "backing type" for extern / packed unions
(`Type.unionBackingType`). For extern unions, this is a `u8` array, for packed
unions it's an integer matching the `bitSize` of the union. Whenever union
memory is read at comptime, it's read as this type.
When union memory is written at comptime, the tag may still be known. If so, the
memory is written using the tagged type. If the tag is unknown (because this
union had previously been read from memory), it's simply written back out as the
backing type.
I added `write_packed` to the `reinterpret` field of
`ComptimePtrMutationKit`. This causes writes of the operand to be packed - which
is necessary when writing to a field of a packed union. Without this, writing a
value to a `u1` field would overwrite the entire byte it occupied.
The final case to address was reading a different (potentially larger) field
from a union when it was written with a known tag. To handle this, a new kind of
bitcast was introduced (`bitCastUnionFieldVal`) which supports reading a larger
field by using a backing buffer that has the unwritten bits set to
undefined. The reason to support this (vs always just writing the union as it's
backing type), is that no reads to larger fields ever occur at comptime, it
would be strictly worse to have spent time writing the full backing type.
Instead of linear search every time a packed struct field's bit or byte
offset is wanted, they are computed once during resolution of the packed
struct's backing int type, and stored in InternPool for O(1) lookup.
Closes#17178
This commit introduces the new `ref_coerced_ty` result type into AstGen.
This represents a expression which we want to treat as an lvalue, and
the pointer will be coerced to a given type.
This change gives known result types to many expressions, in particular
struct and array initializations. This allows certain casts to work
which previously required explicitly specifying types via `@as`. It also
eliminates our dependence on anonymous struct types for expressions of
the form `&.{ ... }` - this paves the way for #16865, and also results
in less Sema magic happening for such initializations, also leading to
potentially better runtime code.
As part of these changes, this commit also implements #17194 by
disallowing RLS on explicitly-typed struct and array initializations.
Apologies for linking these changes - it seemed rather pointless to try
and separate them, since they both make big changes to struct and array
initializations in AstGen. The rationale for this change can be found in
the proposal - in essence, performing RLS whilst maintaining the
semantics of the intermediary type is a very difficult problem to solve.
This allowed the problematic `coerce_result_ptr` ZIR instruction to be
completely eliminated, which in turn also simplified the logic for
inferred allocations in Sema - thanks to this, we almost break even on
line count!
In doing this, the ZIR instructions surrounding these initializations
have been restructured - some have been added and removed, and others
renamed for clarity (and their semantics changed slightly). In order to
optimize ZIR tag count, the `struct_init_anon_ref` and
`array_init_anon_ref` instructions have been removed in favour of using
`ref` on a standard anonymous value initialization, since these
instructions are now virtually never used.
Lastly, it's worth noting that this commit introduces a slightly strange
source of generic poison types: in the expression `@as(*anyopaque, &x)`,
the sub-expression `x` has a generic poison result type, despite no
generic code being involved. This turns out to be a logical choice,
because we don't know the result type for `x`, and the generic poison
type represents precisely this case, providing the semantics we need.
Resolves: #16512Resolves: #17194
