[libc++abi][AIX] add personality and helper functions for the state table EH
Summary:
This patch adds the personality and helper functions for the state table based EH used by IBM legacy compilers xlC and xlclang++ on AIX.
* A high level description of the state table based EH is provided in the code comments.
* Function scan_state_tab() is added to scan the state table. It is invoked by the state table personality routine __xlcxx_personality_v0() and returns scan_results like scan_eh_tab() does.
* A couple of EH helper functions used by xlC and xlclang++ generated code are also added, e.g., __xlc_catch_matchv2() which checks whether the thrown object matches the catch handler's exception type.
* Debugging macros _LIBCXXABI_TRACE_STATETAB, _LIBCXXABI_TRACE_STATETAB0, and _LIBCXXABI_TRACING_STATETAB are added to dump state table scanning traces if environment variable LIBCXXABI_PRINT_STATTAB is set.
* The state variable and state table data is the LSDA found from the traceback table of the function during unwinding.
Reviewed by: MaskRay, cebowleratibm, libc++abi
Differential Revision: https://reviews.llvm.org/D100504
GitOrigin-RevId: b8f5732634feaf7a9ce37d33f97f1fb490efeddd
2 files changed
