[Bug tree-optimization/85190] [8 Regression] gcc.dg/vect/pr81196.c FAILs

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85190

--- Comment #3 from amker at gcc dot gnu.org ---
(In reply to Rainer Orth from comment #0)
> The gcc.dg/vect/pr81196.c testcase started to FAIL between 20180326
> (r258856) and 20180327 (r258886)
> on a couple of targets:
> 
> +FAIL: gcc.dg/vect/pr81196.c -flto -ffat-lto-objects  scan-tree-dump-times
> vect "vectorized 1 loops" 2
> 
> gcc.dg/vect/pr81196.c: pattern found 0 times
> 
> +FAIL: gcc.dg/vect/pr81196.c scan-tree-dump-times vect "vectorized 1 loops" 2
> 
> I'm seeing it on Solaris/x86 (32 and 64-bit), and there are similar
> testresults
> for FreeBSD, Linux/x86, Linux/PowerPC64, and SPU.

Hmm, what options did you use?
For example,
@r258886 I configured powerpc64 like:
$ ../gcc/configure --enable-languages=c,fortran,c++ --with-cpu=power8
--disable-bootstrap 

Then compile the test case with below options:
./powerpc64le-unknown-linux-gnu-gcc -S -O2 -ftree-vectorize pr81196.c -o
pr81196.S -fdump-tree-ifcvt -fdump-tree-vect-details -flto -ffat-lto-objects
-mcpu=power6/7/8

power6/power7 would fail, but on power8 loops are vectorized.

Problem is, on power6/power7, the case would fail even for r258856 as you
bisected.