disable ldist for test, to restore vectorizing-candidate loop

[Alexandre Oliva <oliva@adacore.com>]

The loop we're supposed to try to vectorize in
gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c is turned into a memset
before the vectorizer runs.

Various other tests in this set have already run into this, and the
solution has been to disable this loop distribution transformation,
enabled at -O2, so that the vectorizer gets a chance to transform the
loop and, in this testcase, fail to do so.

This was regstrapped on x86_64-linux-gnu, tested with a cross to a
ppc64-vxworks7r2, and I'm now also regstrapping on ppc64-linux-gnu just
to be sure.  Ok to install?


for  gcc/testsuite/ChangeLog

	* gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c: Disable
	ldist.
---
 .../gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c b/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c
index 72b4930d9bbbe..0d48dfea7bcf2 100644
--- a/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c
@@ -1,4 +1,5 @@
 /* { dg-require-effective-target vect_int } */
+/* { dg-additional-options "-fno-tree-loop-distribute-patterns" } */
 
 #include <stdarg.h>
 #include "../../tree-vect.h"

-- 
Alexandre Oliva, happy hacker  https://FSFLA.org/blogs/lxo/
   Free Software Activist         GNU Toolchain Engineer
        Vim, Vi, Voltei pro Emacs -- GNUlius Caesar