BOLT hardcoded 4-byte LSDA (exception table) encoding for x86-64. This
is insufficient for large code model binaries where functions in .ltext
sections may be placed at addresses above 2GB, exceeding the range of
DW_EH_PE_udata4/DW_EH_PE_sdata4 encodings.
Detect large code model by checking for .ltext sections
(SHF_X86_64_LARGE) and update LSDAEncoding to use 8-byte pointers:
- Non-PIC: DW_EH_PE_absptr (8-byte absolute)
- PIC: DW_EH_PE_pcrel | DW_EH_PE_sdata8 (8-byte PC-relative)
This was pulled out from
https://github.com/llvm/llvm-project/pull/190637
ec1e3aef9a