[Bug tree-optimization/107855] gcc.dg/vect/vect-ifcvt-18.c FAILs

["ro at CeBiTec dot Uni-Bielefeld.DE" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107855

--- Comment #8 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #6 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
> Hmm, the test contains
>
> "/* { dg-additional-options "-Ofast -mavx" { target avx_runtime } } */"
>
> So it passes on AVX capable native builds, but fails otherwise.

I can reproduce things in a VM now: when it doesn't have avx support,
the test is compiled with -msse2 only and FAILs both for the dump and
execution:

FAIL: gcc.dg/vect/vect-ifcvt-18.c -flto -ffat-lto-objects  scan-tree-dump vect
"vectorized 3 loops"
FAIL: gcc.dg/vect/vect-ifcvt-18.c -flto -ffat-lto-objects execution test
FAIL: gcc.dg/vect/vect-ifcvt-18.c execution test
FAIL: gcc.dg/vect/vect-ifcvt-18.c scan-tree-dump vect "vectorized 3 loops"

The test aborts here:

Thread 2 received signal SIGABRT, Aborted.

#0  0xfe26e385 in __lwp_sigqueue () from /lib/libc.so.1
#1  0xfe2660ef in thr_kill () from /lib/libc.so.1
#2  0xfe19db82 in raise () from /lib/libc.so.1
#3  0xfe16b1f4 in abort () from /lib/libc.so.1
#4  0x08050d58 in main ()
    at
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:34

and the dump shows

/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
note:  === analyze_loop_nest ===
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
note:   === vect_analyze_loop_form ===
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
note:   using as main loop exit: 13 -> 14 [AUX: 0]
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
missed:   not vectorized: unsupported control flow in loop.
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
missed:  bad loop form.
/vol/gcc/src/hg/master/local/gcc/testsuite/gcc.dg/vect/vect-ifcvt-18.c:28:17:
missed: couldn't vectorize loop

When I add avx support to the VM, the test PASSes.

It seems the test is missing some requirement here.