aaron.ballman added a comment.
> First, to build linux kernel with btf_tag annotated user pointer, we have
>
> #define __user __attribute__((btf_tag("user")))
> and the linux kernel contains code like below ([2])
>
> typedef __signalfn_t __user *__sighandler_t;
> and the user attribute applies to typedef type sighandler_t.
> So clang needs to support btf_tag attribute with typedef type
> to avoid compilation error.
I want to make sure we're clear on the semantics here. That defines
`__sighandler_t` to be the type `__signalfn_t __user *`, so you expect this to
annotate the type, not the declaration of the typedef. So this is about
allowing `btf_tag` on types in addition to declarations?
> typedef struct { ... } target_type __btf_tag
Similar here -- this applies the __btf_tag to the type, not to the declaration
of the typedef, right?
I'm asking because this raises other questions. For example:
void func(int i);
void func(int __attribute__((btf_tag("__user"))) i);
Is the second a valid redeclaration of the first? Additionally:
__attribute__((overloadable)) void func(int i) { puts("one"); }
__attribute__((overloadable)) void func(int
__attribute__((btf_tag("__user"))) i) { puts("two"); }
Is this a valid overload set because of the type attribute? Along the same
lines, does adding this attribute to the type cause any ABI differences in how
the type is passed?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D110127/new/
https://reviews.llvm.org/D110127
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