In end(), the freelist pointer is owned so the bare store would be ok.
However, there is a load in start() that can happen at the same time, if
another start() and end() pair grabs that same index.
I don't think this fixes#21663 actually because even if the data race
corrupts the value for `next`, the cmpxchg protects the value from being
stored there.
This commit finishes implementing #21209 by removing the
`@setAlignStack` builtin in favour of `CallingConvention` payloads. The
x86_64 backend is updated to use the stack alignment given in the
calling convention (the LLVM backend was already updated in a previous
commit).
Resolves: #21209
The old `CallingConvention` type is replaced with the new
`NewCallingConvention`. References to `NewCallingConvention` in the
compiler are updated accordingly. In addition, a few parts of the
standard library are updated to use the new type correctly.
This commit begins implementing accepted proposal #21209 by making
`std.builtin.CallingConvention` a tagged union.
The stage1 dance here is a little convoluted. This commit introduces the
new type as `NewCallingConvention`, keeping the old `CallingConvention`
around. The compiler uses `std.builtin.NewCallingConvention`
exclusively, but when fetching the type from `std` when running the
compiler (e.g. with `getBuiltinType`), the name `CallingConvention` is
used. This allows a prior build of Zig to be used to build this commit.
The next commit will update `zig1.wasm`, and then the compiler and
standard library can be updated to completely replace
`CallingConvention` with `NewCallingConvention`.
The second half of #21209 is to remove `@setAlignStack`, which will be
implemented in another commit after updating `zig1.wasm`.
* fix compilation errors for fs and fs.Dir
* mem.span instead of mem.sliceTo
* Updating symLinkAbsoluteW function parameters
* Update with expected rename semantics
These are really answering questions about the Zig compiler's capacity to
provide a libc/libc++ implementation. As such, std.zig.target seems like a more
fitting place for these.
Make shared_objects a StringArrayHashMap so that deduping does not
need to happen in flush. That deduping code also was using an O(N^2)
algorithm, which is not allowed in this codebase. There is another
violation of this rule in resolveSymbols but this commit does not
address it.
This required reworking shared object parsing, breaking it into
independent components so that we could access soname earlier.
Shared object parsing had a few problems that I noticed and fixed in
this commit:
* Many instances of incorrect use of align(1).
* `shnum * @sizeOf(elf.Elf64_Shdr)` can overflow based on user data.
* `@divExact` can cause illegal behavior based on user data.
* Strange versyms logic that wasn't present in mold nor lld. The logic
was not commented and there is no git blame information in ziglang/zig
nor kubkon/zld. I changed it to match mold and lld instead.
* Use of ArrayList for slices of memory that are never resized.
* finding DT_VERDEFNUM in a different loop than finding DT_SONAME.
Ultimately I think we should follow mold's lead and ignore this
integer, relying on null termination instead.
* Doing logic based on VER_FLG_BASE rather than ignoring it like mold
and LLD do. No comment explaining why the behavior is different.
* Mutating the original ELF symbols rather than only storing the mangled
name on the new Symbol struct.
I noticed something that I didn't try to address in this commit: Symbol
stores a lot of redundant information that is already present in the ELF
symbols. I suspect that the codebase could benefit from reworking Symbol
to not store redundant information.
Additionally:
* Add some type safety to std.elf.
* Eliminate 1-3 file system reads for determining the kind of input
files, by taking advantage of file name extension and handling error
codes properly.
* Move more error handling methods to link.Diags and make them
infallible and thread-safe
* Make the data dependencies obvious in the parameters of
parseSharedObject. It's now clear that the first two steps (Header and
Parsed) can be done during the main Compilation pipeline, rather than
waiting for flush().
