[Bug tree-optimization/35642] New: heisenbug in tree vectorizer

["zadeck at naturalbridge dot com" <gcc-bugzilla at gcc dot gnu dot org>]

with svn version 133159 the following bugs show up in the tree vectorizer if
you do not bootstrap the compiler:

FAIL: gcc.dg/vect/vect-strided-store-u16-i4.c scan-tree-dump-times vect
"vectorized 1 loops" 2
FAIL: gcc.dg/vect/vect-vfa-03.c scan-tree-dump-times vect "vectorized 1 loops"
1
XPASS: gcc.dg/vect/vect-vfa-03.c scan-tree-dump-times vect "vectorized 1 loops"
0
FAIL: gcc.dg/vect/slp-21.c scan-tree-dump-times vect "vectorized 4 loops" 1
FAIL: gcc.dg/vect/slp-21.c scan-tree-dump-times vect "vectorizing stmts using
SLP" 2

and the bugs go away when you bootstrap.   I have made modifications to
register allocator, and these downstream changes cause the compiler to be
enough different so that the bugs become hard failures.    

however the bugs are easily reproducible by 

--enable-languages=c --with-cpu=default-32 --disable-multilib 
--disable-bootstrap 

with this version of the compiler.  I have not played around with this in other
revisions.  I know that this combo will reproduce the issue.  Since this is
most likely a storage leak or an uninitialized variable, it is important to
recreate the environment exactly.

Kenny


-- 
           Summary: heisenbug in tree vectorizer
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zadeck at naturalbridge dot com
 GCC build triplet: powerpc-unknown-linux-gnu  32 bit compiler


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35642