Broken GAS DWARF tests

[Mark Wielaard]

On Thu, Jul 30, 2020 at 04:21:17PM +0100, Nick Clifton via Binutils wrote:
> Hi Tom,
> 
> > Nick> 	* as.c (dwatf_level): Default to level 3 in case version is not
> > Nick> 	set on the command line.
> > 
> > I understand not wanting to pick DWARF 5 as a default, since it still
> > isn't fully supported in gdb; but why not DWARF 4 as the default?
> 
> Simplicity.  Setting the default to 4 broke lots of tests (in the assembler
> and binutils directories).  Setting the default to 3 does not break the tests.
> 
> Plus, and this is very minor, version 4 DWARF line number tables are 
> actually bigger than version 3 tables, because of the addition of the
> Maximum Ops Per Instruction field in the table header.

This is most likely compensated by the fact that for DWARF4 we loose a
relocation in the CU DIE header for DW_AT_high_pc. We could save a few
bytes if we would be able to express the difference between low_pc and
high_pc as uleb128 (maybe we can simply use emit_leb128_expr?).

> But if there is a consensus that version 4 is the way to go, then I can
> change the default and update the tests.

It might be a good idea to upgrade to version 4 for the next binutils
release. DWARF4 was officially published 10 years ago (and DWARF5 3
years ago).

Cheers,

Mark