A new attribute btf_tag is added. The syntax looks like
__attribute__((btf_tag(<string>)))
Users may tag a particular structure/member/function/func_parameter/variable
declaration with an arbitrary string and the intention is
that this string is passed to dwarf so it is available for
post-compilation analysis. The string will be also passed
to .BTF section if the target is BPF. For each permitted
declaration, multiple btf_tag's are allowed.
For detailed use cases, please see
https://lists.llvm.org/pipermail/llvm-dev/2021-June/151009.html
In case that there exist redeclarations, the btf_tag attributes
will be accumulated along with different declarations, and the
last declaration will contain all attributes.
Differential Revision: https://reviews.llvm.org/D106614
1b194ef1ab