Clang 17 passed struct{f128} parameters using rdi and rax, while Clang
18 matches GCC 13.2 behavior, passing them using xmm0.
This commit makes Zig's LLVM backend match Clang 18 and GCC 13.2. The
commit deletes a hack in x86_64/abi.zig which miscategorized f128 as
"memory" which obviously disagreed with the spec.
LLVM now refuses to lower arguments and return values on x86 targets
when the total vector bit size is >= 512.
This code detects such a situation and uses byref instead of byval.
* some manual fixes to generated CPU features code. In the future it
would be nice to make the script do those automatically.
* add to various target OS switches. Some of the values I was unsure of
and added TODO panics, for example in the case of spirv CPU arch.
New OSs:
* XROS
* Serenity
* Vulkan
Removed OSs:
* Ananas
* CloudABI
* Minix
* Contiki
New CPUs:
* spirv
The removed stuff is removed from LLVM but not Zig.
This was a "fake" type used to handle C varargs parameters, much like
generic poison. In fact, it is treated identically to generic poison in
all cases other than one (the final coercion of a call argument), which
is trivially special-cased. Thus, it makes sense to remove this special
tag and instead use `generic_poison_type` in its place. This fixes
several bugs in Sema related to missing handling of this tag.
Resolves: #19781
As of Clang 18, calling memcpy() with a misaligned pointer trips UBSAN,
even if the length is zero. This unfortunately includes any call to
`@memcpy` when source or destination are undefined and the length is
zero.
This patch makes the C backend avoid calling memcpy when the length is
zero, thereby avoiding undefined behavior.
A zig1.wasm update will be needed in the llvm18 branch to activate this
code.
this patch renames ComptimeStringMap to StaticStringMap, makes it
accept only a single type parameter, and return a known struct type
instead of an anonymous struct. initial motivation for these changes
was to reduce the 'very long type names' issue described here
https://github.com/ziglang/zig/pull/19682.
this breaks the previous API. users will now need to write:
`const map = std.StaticStringMap(T).initComptime(kvs_list);`
* move `kvs_list` param from type param to an `initComptime()` param
* new public methods
* `keys()`, `values()` helpers
* `init(allocator)`, `deinit(allocator)` for runtime data
* `getLongestPrefix(str)`, `getLongestPrefixIndex(str)` - i'm not sure
these belong but have left in for now incase they are deemed useful
* performance notes:
* i posted some benchmarking results here:
https://github.com/travisstaloch/comptime-string-map-revised/issues/1
* i noticed a speedup reducing the size of the struct from 48 to 32
bytes and thus use u32s instead of usize for all length fields
* i noticed speedup storing KVs as a struct of arrays
* latest benchmark shows these wall_time improvements for
debug/safe/small/fast builds: -6.6% / -10.2% / -19.1% / -8.9%. full
output in link above.
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: #19452Resolves: #19460
This allows us to more sanely allocate a continuous
range of result-ids, and avoids a bunch of nasty
casting code in a few places. Its currently not used
very often, but will be useful in the future.
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`.
