RTL frontend input format again (was Re: [PATCH 15/16] RTL frontend (rtl1), on top of dump reader)

David Malcolm dmalcolm@redhat.com
Wed Oct 19 17:19:00 GMT 2016


On Wed, 2016-10-19 at 16:41 +0200, Bernd Schmidt wrote:
> On 10/19/2016 04:35 PM, David Malcolm wrote:
> 
> > In r241120 I dropped all dumping of the JUMP_LABEL when adding the
> > "compact" mode.
> > 
> > I'm now running into an issue with this as I update the __RTL in
> > cc1
> > tests to use the new format, since various passes require the
> > JUMP_INSNs to have JUMP_LABEL data.
> 
> Isn't it possible to recreate these? In jump.c we have 
> rebuild_jump_labels, which looks like it'll also compute LABEL_NUSES 
> which I think we were considering dropping in the output.

I already dropped LABEL_NUSES in compact mode in r241120; I think it's
possible to regenerate that information.

But how would we go about recreating the JUMP_LABEL data?  As far as I
can tell, it can be set up by reorg.c:make_return_insns
via comparison against function_return_label and
function_simple_return_label, which are set up by find_end_label; the
functions in question are non-trivial, and can lead to extra insns
being emitted.  Also, in shrink-wrap.c:handle_simple_exit, which has
similar state considerations.

It seems simpler to serialize this information.

Or am I missing something?

Thanks
Dave



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