[Bug tree-optimization/36630] [4.3/4.4 Regression] ICE in vect_update_ivs_after_vectorizer

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from rguenth at gcc dot gnu dot org  2008-08-28 15:09 -------
I still think that handling NULL from evolution_part_in_loop_num is the
correct thing to do.  Even if you need to move this check to the analysis
phase.

The interesting thing is that the access function during
vect_analyze_scalar_cycles_1 is

{2, +, 1}_1

which is because after the vectorized part of the loop the prologue
remains which has a non-constant evolution start.

So with the reasoning that you analyzed the access function of the
original loop properly you can probably strip the conversion that
confuses you at just vect_update_ivs_after_vectorizer.  (Or store
the relevant information during analysis where the evolution is
still simple enough)

This would fix the ICE, but I wonder if it may cause wrong code because
of mismatched types somehow. 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36630