[PR debug/47624] improve value tracking in non-VTA locations

Alexandre Oliva aoliva@redhat.com
Sat Jun 4 10:48:00 GMT 2011

On Feb 15, 2011, Alexandre Oliva <aoliva@redhat.com> wrote:

> VTA only tracks locations of gimple regs, while addressable variables
> still use the old var tracking strategy.  This means addressable
> variables, during var-tracking, got locations that were not based on
> VALUEs, which failed immediately in the presence of auto-inc addresses.
> The locations also tended to degrade in other ways, when a register
> holding an address happened to be overwritten at a later point.

> This patch arranges for us to track addresses of these variables as
> VALUEs, and to emit new locations for them when a location whose value
> was used to compute its address changes, fixing the problem.

> The patch was regstrapped on x86_64-linux-gnu and i686-linux-gnu.  Ok to
> install?

Ping?  Retested on both platforms, unchanged except for fixing the typo
s/deug/debug/ in the ChangeLog entry, that Jakub caught.

> for  gcc/ChangeLog
> from  Alexandre Oliva  <aoliva@redhat.com>

> 	PR deug/47624
> 	* var-tracking.c (add_stores): Add FIXME note.
> 	(compute_bb_dataflow): Use value-based locations in MO_VAL_SET.
> 	(emit_notes_in_bb): Likewise.
> 	(check_changed_vars_4): New.
> 	(emit_noets_for_changes): Call it.

Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer

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