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

[victork at gcc dot gnu dot org]

------- Comment #5 from victork at gcc dot gnu dot org  2008-03-20 09:42 -------
I see same failures using compiler boostrapped with vectorization enabled using
BOOT_CFLAGS="-g -O2 -ftree-vectorize -maltivec -mabi=altivec"

Tests fail because some loops were not vectorized:
home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
vect_is_simple_use: operand 2
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note: op
not supported by target.
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
vect_is_simple_use: operand D.2114_11 * 2
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
not ssa-name.
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
use not simple.
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
not vectorized: relevant stmt not supported: D.2115_12 = D.2114_11 * 2
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:26: note:
bad operation or unsupported loop bound.
/home/victork/mainline/gcc/gcc/testsuite/gcc.dg/vect/vect-vfa-03.c:23: note:
vectorized 0 loops in function.

In above case vect_is_simple_use() has a problem with constant operand, which
is very strange.  Looks like a memory overwrite.


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