This implements the `__wasm_call_ctors` symbol. This symbol is
automatically referenced by libc to initialize its constructors.
We first retrieve all constructors from each object file, and then
create a function body that calls each constructor based on its
priority. Constructors are not allowed to have any parameters, but are
allowed to have a return type. When a return type does exist, we simply
drop its value from the stack after calling the constructor to ensure
we pass the stack validator.
Using zig cc with CMake on Windows was failing during compiler
detection. -nostdinc was causing the crt not to be linked, and Coff/lld.zig
assumed that wWinMainCRTStartup would be present in this case.
-nostdlib did not prevent the default behaviour of linking libc++ when
zig c++ was used. This caused libc++ to be built when CMake ran
ABI detection using zig c++, which fails as libcxxabi cannot compile
under MSVC.
- Change the behaviour of COFF -nostdinc to set /entry to the function that the
default CRT method for the specified subsystem would have called.
- Fix -ENTRY being passed twice if it was specified explicitly and -nostdlib was present.
- Add support for /pdb, /version, /implib, and /subsystem as linker args (passed by CMake)
- Remove -Ddisable-zstd, no longer needed
- Add -Ddisable-libcpp for use when bootstrapping on msvc
- add support for passing through .def files to the linker,
required for building libLTO.dll in LLVM
- fixup libcpp linking conditionals
- add option to skip linking zstd for use in bootstrapping (when
building against an LLVM with LLVM_ENABLE_ZSTD=OFF)
In #1622, when targeting WebAsembly, the --allow-undefined flag
became unconditionally added to the linker.
This is not always desirable.
First, this is error prone. Code with references to unkown symbols
will link just fine, but then fail at run-time.
This behavior is inconsistent with all other targets.
For freestanding wasm applications, and applications that only use
WASI, undefined references are better reported at compile-time.
This behavior is also inconsistent with clang itself. Autoconf and
cmake scripts checking for function presence think that all tested
functions exist, but then resulting application cannot run.
For example, this is one of the reasons compilation of Ruby 3.2.0
to WASI fails with zig cc, while it works out of the box with clang.
But all applications checking for symbol existence before compilation
are affected.
This reverts the behavior to the one Zig had before #1622, and
introduces an `import_symbols` flag to ignore undefined symbols,
assuming that the webassembly runtime will define them.
Considering all possible features are known by the linker during
compile-time, we can create arrays on the stack instead of
dynamically allocating hash maps. We use a simple bitset to determine
whether a feature is enabled or not, and from which object file
it originates. This allows us to make feature validation slightly
faster and use less runtime memory.
In the future this could be enhanced further by having a single
array instead with a more sophisticated bitset.
This makes it easier to understand how control flow should happen in
various cases; already just by doing this it is revealed that
UndefinedSymbol and UndefinedSymbolReference should be merged, and that
MissingMainEntrypoint should be removed in favor of the ErrorFlags
mechanism thath we already have for missing the main entrypoint.
The main motivation for this change, however, is preventing a compile
error when there is conditional compilation inside linker
implementations, causing the flush() error set to depend on compilation
options. With this change, the error set is fixed, and, notably, the
`-Donly-c` flag no longer has compilation errors due to this error set.
This option can be used to produce a C backend build of the self-hosted
compiler, which only has the C backend enabled. Once the C backend is
capable of self-hosting, this will be a way for us to replace our stage1
codebase with a C backend build of self-hosted, which we can then use
for bootstrapping. See #5246 for more details.
Using this option right now results in a crash because the C backend is
not yet passing all the behavior tests.
Windows gives AccessDenied if you delete a directory which contains open
file handles. This could be triggered when using CacheMode.whole when
cross compiling macho test binaries.
This adds the following for passthrough to lld:
- `--print-gc-sections`
- `--print-icf-sections`
- `--print-map`
I am not adding these to the cache manifest, since it does not change
the produced artifacts.
Tested with an example from #11398: it successfully prints the resulting
map and the GC'd sections.
This is problematic because in practice it depends on whether the
compiler backend supports it too, as evidenced by the TODO comment about
LLVM not supporting some architectures that in fact do support tail
calls.
Instead this logic is organized strategically in src/target.zig, part of
the internal compiler source code, and the behavior tests in question
duplicate some logic for deciding whether to proceed with the test.
The proper place to expose this flag is in `@import("builtin")` - the
generated source file - so that third party compilers can advertise
whether they support tail calls.
From `copy_file_range(2)` errors:
ETXTBSY
Either fd_in or fd_out refers to an active swap file.
Same error will be used in the upcoming `ioctl_ficlonerange(2)`:
ETXTBSY
One of the files is a swap file. Swap files cannot share storage.
This commit enables `-u <symbol>` for ELF and `-include:<symbol>` for
COFF linkers for use internally. This means we do not expose these
flags to the users just yet, however, we make use of them internally
whenever required. One such use case is forcing inclusion of
`_tls_index` when linking for Windows with mingw and LTO and dead
code stripping enabled. This ensures we add `_tls_index` to the symbol
resolver as an undefined symbol and force the linker to include an atom
that provides it marking it a dead-code-stripping root - meaning it will
not be garbage collected by the linker no matter what.
Firstly, opening a file handle is not really needed since we won't even
use it, and secondly, this can cause AccessDenied errors on Windows
when trying to move a directory from zig-cache/tmp/ to zig-cache/o/
since, without POSIX semantics, it is illegal to move directories
with open handles to any of its resources.
