[gcc r15-18] disable ldist for test, to restore vectorizing-candidate loop

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:cc6a439fdab933963b00c488e221ae33d7199aeb

commit r15-18-gcc6a439fdab933963b00c488e221ae33d7199aeb
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Sun Apr 28 04:30:15 2024 -0300

    disable ldist for test, to restore vectorizing-candidate loop
    
    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.
    
    
    for  gcc/testsuite/ChangeLog
    
            * gcc.dg/vect/costmodel/ppc/costmodel-vect-31a.c: Disable
            ldist.

Diff:
---
 gcc/testsuite/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 454a714a309..90b5d5a7f40 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"