[Dwarf-Discuss] Split Dwarf vs. CU DW_AT_ranges / DW_AT_low_pc placement

[Jakub Jelinek]

On Wed, Mar 10, 2021 at 01:16:24PM -0800, Cary Coutant wrote:
> > But what about the DW_AT_ranges on the skeleton CU when using split DWARF?
> >
> > Are you suggesting that both LLVM and GCC's emission is incorrect - and that it's not possible to use rnglistx in the skeleton CU (instead you must use sec_offset for DW_AT_ranges on the skeleton CU)? (& that there's no way to refer to range lists in the .o (debug_rnglists) from the .dwo - all ranges in the split full unit must be in debug_rnglists.dwo?)
> 
> If you've moved range lists over to the dwo, having DW_AT_ranges in
> the skeleton CU would be pointless ? the consumer would still have to
> go find the dwo to get the ranges.

My current patch to start using .debug_rnglists.dwo in GCC for -gdwarf-5 -gstrict-dwarf
will emit DW_AT_ranges in the .debug_info.dwo only (both in the CU and other
DIEs there), but if I need a DW_AT_low_pc for the base address too, do you think
it is ok to keep it in the DW_TAG_skeleton_unit with DW_FORM_addr?
If I had to move it to .debug_info.dwo DW_TAG_compile_unit, it would need to
be DW_FORM_addrx there and in the end would require larger size.

	Jakub