jacek added a comment.
In D157547#4650643 <https://reviews.llvm.org/D157547#4650643>, @efriedma wrote:
> Seems to be working for simple cases, but I'm not sure this is actually
> working properly (I'm still seeing LNK1000 crashes).
I don't know if it's related to crashes that you're seeing, but those
anti-dependency symbols look different than what MSVC produces. With the patch,
I get:
$ cat extfunc.c
extern void extfunc(void);
void func(void) { extfunc(); }
$ clang -target arm64ec-windows -c extcall.c -o extcall.o
$ llvm-readobj --symbols extcall.o
...
Symbol {
Name: #extfunc
Value: 0
Section: IMAGE_SYM_UNDEFINED (0)
BaseType: Null (0x0)
ComplexType: Null (0x0)
StorageClass: WeakExternal (0x69)
AuxSymbolCount: 1
AuxWeakExternal {
Linked: .weak.#extfunc.default.#func (40)
Search: AntiDependency (0x4)
}
}
...
Symbol {
Name: extfunc
Value: 0
Section: IMAGE_SYM_UNDEFINED (0)
BaseType: Null (0x0)
ComplexType: Null (0x0)
StorageClass: WeakExternal (0x69)
AuxSymbolCount: 1
AuxWeakExternal {
Linked: #extfunc$exit_thunk (43)
Search: AntiDependency (0x4)
}
}
While an equivalent object file produced by MSVC has:
Symbol {
Name: #extfunc
Value: 0
Section: IMAGE_SYM_UNDEFINED (0)
BaseType: Null (0x0)
ComplexType: Function (0x2)
StorageClass: WeakExternal (0x69)
AuxSymbolCount: 1
AuxWeakExternal {
Linked: #extfunc$exit_thunk (14)
Search: AntiDependency (0x4)
}
}
Symbol {
Name: extfunc
Value: 0
Section: IMAGE_SYM_UNDEFINED (0)
BaseType: Null (0x0)
ComplexType: Function (0x2)
StorageClass: WeakExternal (0x69)
AuxSymbolCount: 1
AuxWeakExternal {
Linked: #extfunc (19)
Search: AntiDependency (0x4)
}
}
It's the mangled symbol that's linked to guest exit thunk, not unmangled one.
Also there is no .weak.*.default.* involved.
BTW, I hope to get my WIP lld-link branch into usable state very soon and plan
to publish it then. I'm able to link real-world code now, but it still requires
a few hacks that I need to fix to make it work out of the box. Hopefully it
will make testing and debugging such problems easier.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157547/new/
https://reviews.llvm.org/D157547
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