On Tue, Sep 01, 2015 at 12:09:48PM +0200, Richard Biener wrote:
>
> So I finally got around to dig into why some testcases I inspected for
> early LTO debug (and some existing guality FAILs) happen. They happen
> because we screw up locations of insns coming from TERed SSA defs
> which end up using the TERed-into stmt location. So final re-building
> the BLOCK tree ends up with no stmts in those BLOCKs and thus we
> don't get any location annotations (even if the var location notes
> are there).
>
> It looks like expand_expr_real_2 might have been designed to use
> ops.location but in fact it only uses that when building other trees. For
> singles we already adjust curr_insn_location, so the following does
> that for all defs.
>
> This seems to explain the guality degradation over the years (we
> just got better in coalescing / TERing...).
>
> In my dev tree this fixes all non-LTO, non-VLA guality FAILs, now
> bootstrapping and testing on x86_64-unknown-linux-gnu.
>
> Note this patch can cause some extra jumping around between locations
> in gdb - but that's expected I guess. It probably also causes some
> debug-info growth.
>
> Ok for trunk if testing succeeds? Ok to backport?
I'd say ok for trunk, wait some time before backport.
> 2015-09-01 Richard Biener <rguent...@suse.de>
>
> * expr.c (expand_expr_real_1): For expanding TERed defs
> set the current location to that of the def if not UNKNOWN.
Jakub
