HPPA64: Use aligned encoding for EH data on 64-bit HP-UX.
GCC now uses aligned Dwarf EH encodings on HP-UX due to dynamic linker limitations.
GCC’s HPPA64 backend now uses DW_EH_PE_aligned encoding for exception handling data on 64-bit HP-UX. Testing revealed that the HP-UX dynamic linker doesn’t support unaligned DW_EH_PE_absptr encodings. This change ensures compatibility with GNU ld and the HP-UX dynamic linker.
In Details
This commit modifies ASM_PREFERRED_EH_DATA_FORMAT in config/pa/pa.h to enforce DW_EH_PE_aligned encoding for HPPA64 on HP-UX. This avoids issues with the HP-UX dynamic linker, which does not support unaligned absolute pointer encodings in exception handling data. The change impacts code generation for exception handling on HP-UX, ensuring compatibility with the platform's dynamic linker.
For Context
When a program throws an exception, the system needs to find the right code to handle it. This involves looking up tables that describe where the exception handling code is located. These tables contain pointers, which are memory addresses that tell the system where to find the code. This commit aligns those pointers on HP-UX to meet dynamic linker requirements.