[PATCH] combine: Delete EQ* notes when pseudo mode changes (PR60818)

[Segher Boessenkool]

On Fri, Feb 19, 2016 at 11:27:48AM +0100, Eric Botcazou wrote:
> > 2016-02-19  Segher Boessenkool  <segher@kernel.crashing.org>
> > 
> > 	PR 60818/rtl-optimization
> > 	* combine.c (combine_remove_reg_equal_equiv_notes_for_regno):
> > 	New function.
> > 	(try_combine): Call it when SELECT_CC_MODE makes us change the
> > 	mode of a pseudo.
> 
> This looks like a big hammer to me though.

Do you have something smaller in mind that still works?  I'm all ears.

> > +/* Remove all REG_EQUAL and REG_EQUIV notes referring to REGNO.  This is
> > +   like rtlanal's remove_reg_equal_equiv_notes_for_regno but with some big
> > +   differences, because combine does not keep the DF info up-to-date.
> > +   We do however never add or move these notes during combine, so we can
> > +   still use the DF info as it was at the start of combine to find all
> > +   such notes.  */
> 
> The comment is wrong, or at least confusing, since distribute_notes does deal 
> with REG_EQUAL and REG_EQUIV notes.

But it never adds or moves these notes.  It even says so :-)


Segher