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Re: fwprop: fix REG_DEAD notes rendered incorrect
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Alexandre Oliva <aoliva at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 27 Oct 2011 15:32:17 +0200
- Subject: Re: fwprop: fix REG_DEAD notes rendered incorrect
- References: <orr51y3744.fsf@livre.localdomain>
> fwprop may propagate a SET_SRC that contains the last use of a REG to a
> later point, but it will leave the REG_DEAD note in place, even though
> it is no longer correct. I noticed this while investigating PR50826:
> the initialization of the internal_arg_pointer has a REG_DEAD note for
> %r29, but even after it is fwpropped, the note remains there. This
> patch fixes this bug.
This isn't necessarily a bug, i.e. passes aren't required to maintain REG_DEAD
and REG_UNUSED notes up-to-date (another example is PR rtl-opt/48773). Instead
passes consuming these notes have to invoke df_note_add_problem on entry.
--
Eric Botcazou