Support DWARF version 5 operations and corresponding GNU extensions

[philipc]

My rust binaries are linked with objects that use DW_OP_GNU_entry_value. Now that gimli's dwarfdump is displaying locs, it panics when trying to dump my rust binaries.

I think I've seen DW_OP_GNU_implicit_pointer in use somewhere too.

DWARF 5 operations:

• DW_OP_implicit_pointer
• DW_OP_addrx
• DW_OP_constx
• DW_OP_entry_value
• DW_OP_const_type
• DW_OP_regval_type
• DW_OP_deref_type
• DW_OP_xderef_type
• DW_OP_convert
• DW_OP_reinterpret

[tromey]

dwarf2.def lists the GNU extensions and in most cases provides a link to documentation:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=include/dwarf2.def;h=64850714ca436e988a11dfeef4d22ea0dc437c59;hb=HEAD#l598

Not all of these are in active use. DW_OP_GNU_encoded_addr isn't implemented by gdb, so probably not used. IIRC DW_OP_GNU_uninit isn't generated by GCC by default. The others can be generated though. Note that the typed stack stuff will need relatively large changes to the evaluator.

[tromey]

Also, I think it would be better not to panic when dumping something unknown.

[philipc]

Also, I think it would be better not to panic when dumping something unknown.

Yeah, gimli's dwarfdump currently uses expect everywhere. This is fine as a validation tool. Definitely should be fixed if dwarfdump is going to see general usage, but that's not a high priority goal for me now (and if that were the goal, then I would probably stop trying to clone libdwarf's dwarfdump output so closely).

[tromey]

The DWARF 5 draft is out now and promotes these to standard.

[philipc]

DW_OP_implicit_pointer and DW_OP_entry_value implemented in #150

[tromey]

I started work on this here: https://github.com/tromey/gimli/tree/dwarf-5-eval. But it needs a rebase and isn't complete.

[philipc]

Typed operations were implemented in #293. DW_OP_addrx was started in #242.

[philipc]

DW_OP_addrx and DW_OP_constx were implemented in #358. All done!