[PATCH v2] aarch64: Emit jump slot for conditional branches to weak_undef

[Siddhesh Poyarekar]

On 16/05/20 16:43, Wilco Dijkstra wrote:
> Hi Siddhesh,
> 
> So how does this work if the PLT slot is out of range? Or if the section is larger than
> the maximum range of the conditional branch? It seems to me doing this will create
> new branch range issues.

Not really, the branch range issues were already there.  Out of range
targets will generate an error like they do for non-PLT conditional
branches.  My understanding is that we do not extend range of
conditional branches by choice.  If range extension is desirable for
conditional branches too, I can post that as a follow-up fix.  In fact
anything that makes the conditional and unconditional branch behaviour
similar would simplify the code; that includes replacing branches to
weak_undef targets with a NOP.

This patch only makes the behaviour of conditional branches with
non-weak undefined symbols[1] a bit more sane and in line with lld.

Siddhesh

[1] I just noticed I wrote weak_undef in the subject line; that's wrong
and I'll fix that up to just "undefined" before committing.