[Bug c++/34459] [4.1/4.3 Regression] incorrect code when compiled with optimization (-O1)

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2007-12-19 20:49 -------
I have bootstrapped/regtested this patch on x86_64-linux with:
               {                                                
                 record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
                 return;
               }
replaced with gcc_unreachable () to see where it hits.  It bootstrapped fine,
the
only regression was the newly added tests (which works with the original patch,
obviously with that gcc_unreachable () ICEs) and gcc.dg/uninit-E.c reports
the warning on line 8 rather than expected 7 (because the i = i; statement
is optimized out by the gimplify.c hunk).  So perhaps the gimplify.c hunk in
that patch isn't a good idea and we should eliminate the nop moves later on
(either during DCE, or some other pass, suggestions?  But that can be left
for a separate patch, keeping just tree-ssa-dse.c (dse_optimize_stmt) hunk
together with the new 20071219-1.c test as the fix for this PR.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34459