[Bug tree-optimization/31976] [4.3 Regression] ICE in ssa_operand_alloc, at tree-ssa-operands.c:487 with -O3

[rguenther at suse dot de]

------- Comment #14 from rguenther at suse dot de  2007-11-07 15:05 -------
Subject: Re:  [4.3 Regression] ICE in
 ssa_operand_alloc, at tree-ssa-operands.c:487 with -O3

On Wed, 7 Nov 2007, dnovillo at google dot com wrote:

> Subject: Re:  [4.3 Regression] ICE in ssa_operand_alloc, at
> tree-ssa-operands.c:487 with -O3
> 
> On 7 Nov 2007 13:52:29 -0000, amacleod at redhat dot com
> <gcc-bugzilla@gcc.gnu.org> wrote:
> 
> > There is also an issue with partitioning, but it would then hide what I
> > think is an important issue.
> >
> > Partitioning's problem is that it counts the number of items in the
> > alias set and just uses that.  There is only one entry for an entire SFT
> > list, so it misses the other 819 in this particular list. The difficulty
> > is determining how many of those SFTs are actually going to be
> > relevant.  Ideally, partitioning would share code with VOP processing so
> > it can see exactly how many VOPs would be generated by each MEM.
> 
> Agreed.  The partitioner heuristics got severely skewed when we
> switched alias sets to only contain the first SFT in the pointed-to
> structure.  But that should be a relatively simple fix.

It actually contains all pointed-to SFTs.  But yes, we should be able
to fix this by conservatively counting VOPs (that is, rather 
overestimate).  I plan to look at the heuristics as soon as we settled
on a fix for the wrong-code PR33870.

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31976