[PATCH] Fix PR38851, missing DSE of zero-sized stores

Richard Guenther rguenther@suse.de
Mon Jan 26 11:26:00 GMT 2009


On Mon, 26 Jan 2009, Steven Bosscher wrote:

> [xf. http://gcc.gnu.org/ml/gcc-patches/2009-01/msg01265.html]
> 
> > Index: gcc/tree-ssa-dse.c
> > ===================================================================
> > *** gcc/tree-ssa-dse.c.orig	2009-01-25 22:57:52.000000000 +0100
> > --- gcc/tree-ssa-dse.c	2009-01-25 22:58:07.000000000 +0100
> > *************** along with GCC; see the file COPYING3.
> > *** 34,39 ****
> > --- 34,40 ----
> >   #include "tree-dump.h"
> >   #include "domwalk.h"
> >   #include "flags.h"
> > + #include "langhooks.h"
> 
> Looks like spitting in the face of LTO :-)
> 
> Is there no way to fix this without introducing new uses of langhooks
> in the middle end?

Well, try to fix the patch doing the same during gimplification.  Or
just wait until after we gimplify unit-at-a-time which should
hopefully fix the fallout I have seen.  Or as Mark suggested add
yet another flag to types to say "yes, this is really zero-size".

;)

At least I expect the above to not last long during 4.5.

Richard.



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