We currently have `isRef` return true for any type of union, including
packed unions. This means we can simply load it from the data section
to the exact type we want. In the future we can optimize it so it works
similarly to packed structs below 64 bits which do not get stored in
the data section and are not passed by ref.
Previously we would only store the payload, but not the actual tag
that was set. This meant miscompilations where it would incorrectly
return the tag value.
This also adds a tiny optimization for payloads which are not `byRef`
by directly storing them based on offset, rather than first calculating
a pointer to an offset.
Previously it was incorrectly assumed that all memcopy's generated by
the `memcpy` AIR instruction had an element size of 1 byte. However,
this would result in miscompilations for pointer's to arrays where
the element size of the array was larger than 1 byte. We now corectly
calculate this size.
`-l :path/to/lib.so` behavior on gcc/clang is:
- the path is recorded as-is: no paths, exact filename (`libX.so.Y`).
- no rpaths.
The previous version removed the `:` and pretended it's a positional
argument to the linker. That works in almost all cases, except in how
rules_go[1] does things (the Bazel wrapper for Go).
Test case in #15743, output:
gcc rpath:
0x0000000000000001 (NEEDED) Shared library: [libversioned.so.2]
0x000000000000001d (RUNPATH) Library runpath: [$ORIGIN/x]
gcc plain:
0x0000000000000001 (NEEDED) Shared library: [libversioned.so.2]
zig cc rpath:
0x0000000000000001 (NEEDED) Shared library: [libversioned.so.2]
0x000000000000001d (RUNPATH) Library runpath: [$ORIGIN/x]
zig cc plain:
0x0000000000000001 (NEEDED) Shared library: [libversioned.so.2]
Fixes#15743
[1]: https://github.com/bazelbuild/rules_go
The idea here is that there are two ways we can reference a function at runtime:
* Through a direct call, i.e. where the function is comptime-known
* Through a function pointer
This means we can easily perform a form of rudimentary escape analysis
on functions. If we ever see a `decl_ref` or `ref` of a function, we
have a function pointer, which could "leak" into runtime code, so we
emit the function; but for a plain `decl_val`, there's no need to.
This change means that `comptime { _ = f; }` no longer forces a function
to be emitted, which was used for some things (mainly tests). These use
sites have been replaced with `_ = &f;`, which still triggers analysis
of the function body, since you're taking a pointer to the function.
Resolves: #6256Resolves: #15353
* move `ptrBitWidth` from Arch to Target since it needs to know about the abi
* double isn't always 8 bits
* AVR uses 1-byte alignment for everything in GCC
Also get rid of the TTY wrapper struct, which was exlusively used as a
namespace - this is done by the tty.zig root struct now.
detectTTYConfig has been renamed to just detectConfig, which is enough
given the new namespace. Additionally, a doc comment had been added.
Also remove all the wasi-libc files we used to ship, but never compile.
The latest wasi-libc HEAD has an extra commit (a6f871343313220b76009827ed0153586361c0d5), which makes preopen initialization lazy.
Unfortunately, that breaks quite a lot of things on our end. Applications now need to explicitly call __wasilibc_populate_preopens() everywhere when the libc is linked. That can wait after 0.11.
This commit removes the `field_call_bind` and `field_call_bind_named` ZIR
instructions, replacing them with a `field_call` instruction which does the bind
and call in one.
`field_call_bind` is an unfortunate instruction. It's tied into one very
specific usage pattern - its result can only be used as a callee. This means
that it creates a value of a "pseudo-type" of sorts, `bound_fn` - this type used
to exist in Zig, but now we just hide it from the user and have AstGen ensure
it's only used in one way. This is quite silly - `Type` and `Value` should, as
much as possible, reflect real Zig types and values.
It makes sense to instead encode the `a.b()` syntax as its own ZIR instruction,
so that's what we do here. This commit introduces a new instruction,
`field_call`. It's like `call`, but rather than a callee ref, it contains a ref
to the object pointer (`&a` in `a.b()`) and the string field name (`b`). This
eliminates `bound_fn` from the language, and slightly decreases the size of
generated ZIR - stats below.
This commit does remove a few usages which used to be allowed:
- `@field(a, "b")()`
- `@call(.auto, a.b, .{})`
- `@call(.auto, @field(a, "b"), .{})`
These forms used to work just like `a.b()`, but are no longer allowed. I believe
this is the correct choice for a few reasons:
- `a.b()` is a purely *syntactic* form; for instance, `(a.b)()` is not valid.
This means it is *not* inconsistent to not allow it in these cases; the
special case here isn't "a field access as a callee", but rather this exact
syntactic form.
- The second argument to `@call` looks much more visually distinct from the
callee in standard call syntax. To me, this makes it seem strange for that
argument to not work like a normal expression in this context.
- A more practical argument: it's confusing! `@field` and `@call` are used in
very different contexts to standard function calls: the former normally hints
at some comptime machinery, and the latter that you want more precise control
over parts of a function call. In these contexts, you don't want implicit
arguments adding extra confusion: you want to be very explicit about what
you're doing.
Lastly, some stats. I mentioned before that this change slightly reduces the
size of ZIR - this is due to two instructions (`field_call_bind` then `call`)
being replaced with one (`field_call`). Here are some numbers:
+--------------+----------+----------+--------+
| File | Before | After | Change |
+--------------+----------+----------+--------+
| Sema.zig | 4.72M | 4.53M | -4% |
| AstGen.zig | 1.52M | 1.48M | -3% |
| hash_map.zig | 283.9K | 276.2K | -3% |
| math.zig | 312.6K | 305.3K | -2% |
+--------------+----------+----------+--------+
This is in preparation of removing indirect lowering again. Also
modifies constant() to accept a repr so that both direct as well
as indirect representations can be generated. Indirect is not yet
used, but will be used for globals.
Previously the tag type was generated even if it was nonexistant,
triggering an assertion that an integer type should never have
zero bits. Now its only generated when the tag type is actually emitted.
