| Age | Commit message (Collapse) | Author |
|---|
|
We've got a big one here! This commit reworks how we represent pointers
in the InternPool, and rewrites the logic for loading and storing from
them at comptime.
Firstly, the pointer representation. Previously, pointers were
represented in a highly structured manner: pointers to fields, array
elements, etc, were explicitly represented. This works well for simple
cases, but is quite difficult to handle in the cases of unusual
reinterpretations, pointer casts, offsets, etc. Therefore, pointers are
now represented in a more "flat" manner. For types without well-defined
layouts -- such as comptime-only types, automatic-layout aggregates, and
so on -- we still use this "hierarchical" structure. However, for types
with well-defined layouts, we use a byte offset associated with the
pointer. This allows the comptime pointer access logic to deal with
reinterpreted pointers far more gracefully, because the "base address"
of a pointer -- for instance a `field` -- is a single value which
pointer accesses cannot exceed since the parent has undefined layout.
This strategy is also more useful to most backends -- see the updated
logic in `codegen.zig` and `codegen/llvm.zig`. For backends which do
prefer a chain of field and elements accesses for lowering pointer
values, such as SPIR-V, there is a helpful function in `Value` which
creates a strategy to derive a pointer value using ideally only field
and element accesses. This is actually more correct than the previous
logic, since it correctly handles pointer casts which, after the dust
has settled, end up referring exactly to an aggregate field or array
element.
In terms of the pointer access code, it has been rewritten from the
ground up. The old logic had become rather a mess of special cases being
added whenever bugs were hit, and was still riddled with bugs. The new
logic was written to handle the "difficult" cases correctly, the most
notable of which is restructuring of a comptime-only array (for
instance, converting a `[3][2]comptime_int` to a `[2][3]comptime_int`.
Currently, the logic for loading and storing work somewhat differently,
but a future change will likely improve the loading logic to bring it
more in line with the store strategy. As far as I can tell, the rewrite
has fixed all bugs exposed by #19414.
As a part of this, the comptime bitcast logic has also been rewritten.
Previously, bitcasts simply worked by serializing the entire value into
an in-memory buffer, then deserializing it. This strategy has two key
weaknesses: pointers, and undefined values. Representations of these
values at comptime cannot be easily serialized/deserialized whilst
preserving data, which means many bitcasts would become runtime-known if
pointers were involved, or would turn `undefined` values into `0xAA`.
The new logic works by "flattening" the datastructure to be cast into a
sequence of bit-packed atomic values, and then "unflattening" it; using
serialization when necessary, but with special handling for `undefined`
values and for pointers which align in virtual memory. The resulting
code is definitely slower -- more on this later -- but it is correct.
The pointer access and bitcast logic required some helper functions and
types which are not generally useful elsewhere, so I opted to split them
into separate files `Sema/comptime_ptr_access.zig` and
`Sema/bitcast.zig`, with simple re-exports in `Sema.zig` for their small
public APIs.
Whilst working on this branch, I caught various unrelated bugs with
transitive Sema errors, and with the handling of `undefined` values.
These bugs have been fixed, and corresponding behavior test added.
In terms of performance, I do anticipate that this commit will regress
performance somewhat, because the new pointer access and bitcast logic
is necessarily more complex. I have not yet taken performance
measurements, but will do shortly, and post the results in this PR. If
the performance regression is severe, I will do work to to optimize the
new logic before merge.
Resolves: #19452
Resolves: #19460
|
|
Also reduce ctype pool string memory usage, remove self assignments, and
enable more warnings.
|
|
This deletes a ton of lookups and avoids many UAF bugs.
Closes #19485
|
|
|
|
|
|
Closes #19543
|
|
|
|
Closes #14904
|
|
Closes #18023
|
|
|
|
Legacy anon decls now have three uses:
* Type owner decls
* Function owner decls
* `@export` and `@extern`
Therefore, there are no longer any cases where we wish to explicitly
omit legacy anon decls from the binary. This means we can remove the
concept of an "alive" vs "dead" `Decl`, which also allows us to remove
the separate `anon_work_queue` in `Compilation`.
|
|
Good riddance!
Most of these changes are trivial. There's a fix for a minor bug this
exposed in `Value.readFromPackedMemory`, but aside from that, it's all
just things like changing `intern` calls to `toIntern`.
|
|
`Decl` can no longer store un-interned values, so this field is now
unnecessary. The type can instead be fetched with the new `typeOf`
helper method, which just gets the type of the Decl's `Value`.
|
|
This commit changes how we represent comptime-mutable memory
(`comptime var`) in the compiler in order to implement the intended
behavior that references to such memory can only exist at comptime.
It does *not* clean up the representation of mutable values, improve the
representation of comptime-known pointers, or fix the many bugs in the
comptime pointer access code. These will be future enhancements.
Comptime memory lives for the duration of a single Sema, and is not
permitted to escape that one analysis, either by becoming runtime-known
or by becoming comptime-known to other analyses. These restrictions mean
that we can represent comptime allocations not via Decl, but with state
local to Sema - specifically, the new `Sema.comptime_allocs` field. All
comptime-mutable allocations, as well as any comptime-known const allocs
containing references to such memory, live in here. This allows for
relatively fast checking of whether a value references any
comptime-mtuable memory, since we need only traverse values up to
pointers: pointers to Decls can never reference comptime-mutable memory,
and pointers into `Sema.comptime_allocs` always do.
This change exposed some faulty pointer access logic in `Value.zig`.
I've fixed the important cases, but there are some TODOs I've put in
which are definitely possible to hit with sufficiently esoteric code. I
plan to resolve these by auditing all direct accesses to pointers (most
of them ought to use Sema to perform the pointer access!), but for now
this is sufficient for all realistic code and to get tests passing.
This change eliminates `Zcu.tmp_hack_arena`, instead using the Sema
arena for comptime memory mutations, which is possible since comptime
memory is now local to the current Sema.
This change should allow `Decl` to store only an `InternPool.Index`
rather than a full-blown `ty: Type, val: Value`. This commit does not
perform this refactor.
|
|
initializator syntax
This fixes an issue with boostrapping the compiler using MSVC. There is a CircularBuffer with
an array of length 65536 initialized to undefined, and because the undefined path of `renderValue`
was using `StringLiteral` to render this, the resulting zig2.c would fail to compile using MSVC.
The solution was to move the already-existing array initializer path (used in the non-undefined path)
into StringLiteral, and make StringLiteral aware of the total length so it could decide between which
style of initialization to use. We prefer to use string literals if we can, as this results in the least
amount of emitted C source.
|
|
A pointer type already has an alignment, so this information does not
need to be duplicated on the function type. This already has precedence
with addrspace which is already disallowed on function types for this
reason. Also fixes `@TypeOf(&func)` to have the correct addrspace and
alignment.
|
|
|
|
|
|
|
|
To be honest, I can't be bothered to figure out which commits these
changes should be in.
|
|
Namespace types (`struct`, `enum`, `union`, `opaque`) do not use
structural equality - equivalence is based on their Decl index (and soon
will change to AST node + captures). However, we previously stored all
other information in the corresponding `InternPool.Key` anyway. For
logical consistency, it makes sense to have the key only be the true key
(that is, the Decl index) and to load all other data through another
function. This introduces those functions, by the name of
`loadStructType` etc. It's a big diff, but most of it is no-brainer
changes.
In future, it might be nice to eliminate a bunch of the loaded state in
favour of accessor functions on the `LoadedXyzType` types (like how we
have `LoadedUnionType.size()`), but that can be explored at a later
date.
|
|
This prevents the possibility of not emitting a `.dbg_inline_end`
instruction and reduces the allocation requirements of the backends.
Closes #19093
|
|
Part of an effort to ship more of the compiler in source form.
|
|
This commit eliminates the `dbg_block_{begin,end}` instructions from
both ZIR and AIR. Instead, lexical scoping of `dbg_var_{ptr,val}`
instructions is decided based on the AIR block they exist within. This
is a much more robust system, and also results in a huge drop in ZIR
bytes - around 7% for Sema.zig.
This required some enhancements to Sema to prevent elision of blocks
when they are required for debug variable scoping. This can be observed
by looking at the AIR for the following simple test program with and
without `-fstrip`:
```zig
export fn f() void {
{
var a: u32 = 0;
_ = &a;
}
{
var a: u32 = 0;
_ = &a;
}
}
```
When `-fstrip` is passed, no AIR blocks are generated. When `-fno-strip`
is passed, the ZIR blocks are lowered to true AIR blocks to give correct
lexical scoping to the debug vars.
The changes here incidentally reolve #19060. A corresponding behavior
test has been added.
Resolves: #19060
|
|
Closes #18959
|
|
These used to be lowered elementwise in air, and now are a single air
instruction that can be lowered elementwise in the backend if necessary.
|
|
Attempts to fix the current CI failures introduced by #18983.
|
|
This should avoid the random pointer invalidation crashes.
Closes #18954
|
|
Add type-erased writer and GenericWriter
|
|
This commit only does the file rename to be friendlier to version
control conflicts.
|
|
This change eliminates some problematic recursive logic in InternPool,
and provides a safer API.
|
|
Closes #13178
|
|
This reduces generic instantiations of several write functions.
Before:
```
@as(type, io.writer.Writer(*array_list.ArrayListAligned(u8,null),error{OutOfMemory},(function 'appendWrite')))
@as(type, io.writer.Writer(*codegen.c.IndentWriter(io.writer.Writer(*array_list.ArrayListAligned(u8,null),error{OutOfMemory},(function 'appendWrite'))),error{OutOfMemory},(function 'write')))
```
After:
```
@as(type, io.GenericWriter(io.Writer,error{OutOfMemory},(function 'write')))
```
|
|
Closes #17817
|
|
This reverts commit 2b589783602c5428ecde9dbb3f41a81f85eb0f25.
|
|
This reverts commit 7161ed79c4abcaccdd56fe0b4fbd3d93472d41b8, reversing
changes made to 3f2a65594e1d3c0a4f4943a4ea522e8405db81e0.
Unfortunately, this sat in the PR queue too long and the merge broke the
zig1.wasm bootstrap process.
|
|
cbe: add a system for avoiding collisions with C compiler intrinsics
|
|
I need some indices for a thing...
|
|
|
|
|
|
The motivating problem here was a memory leak in the hash maps of
Module.Namespace.
The commit deletes more of the legacy incremental compilation
implementation. It had things like use of orderedRemove and trying to do
too much OOP-style creation and deletion of objects.
Instead, this commit iterates over all the namespaces on Module deinit
and calls deinit on the hash map fields. This logic is much simpler to
reason about.
Similarly, change global inline assembly to an array hash map since
iterating over the values is a primary use of it, and clean up the
remaining values on Module deinit, solving another memory leak.
After this there are no more memory leaks remaining when using the
x86 backend in a libc-less compiler.
|
|
This was regressed in d657b6c0e2ab7c47f5416dc4df1abb2bfbecd4b6, when
the comptime memory model for unions was changed to allow them to have
no defined tag type.
|
|
|
|
symbols under a different name
|
|
Changes:
- Add `isMangledIdent` to determine if `fmtIdent` would make any edits to the identifier
- Any function that has a mangled identifier is referred to using the mangled identifer
within the current file, but if it is exported the first export will be with the non-mangled name.
- Add `zig_import` to import a symbol under a different name
- Add a level of indirection to float function names. Now, they are referred to as
`zig_float_fn_<float type>_<operation>`. The definitions in zig.h are wrapped
with `zig_import` to import the symbol under the real name.
The specific problem that sparked this change was the combination of
`zig_libc_name_f80(name) __##name##x` with the input `fma`, resulting
in `__fmax`, which is a new intrinsic in recent versions of cl.exe.
With the above changes in place, compiler_rt can output the following:
```
static zig_weak_linkage_fn zig_f80 zig_e___fmax(zig_f80, zig_f80, zig_f80);
zig_export(zig_weak_linkage_fn zig_f80 zig_e___fmax(zig_f80, zig_f80, zig_f80), __fmax, "__fmax");
```
Within compiler_rt, `zig_e___fmax` is used to refer to the function, but consumers
will import `__fmax`, which maps to their `zig_float_fn_f80_fma` definition from zig.h.
|
|
|
|
Let's take this breaking change opportunity to fix the style of this
enum.
|
|
|
|
|
|
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.
|
