[gcc r13-2298] middle-end: Fix unexpected warnings for RISC-V port.

[gcc r13-2298] middle-end: Fix unexpected warnings for RISC-V port.

[Andreas Schwab]

https://gcc.gnu.org/g:a99b53f7e1860b96b67f069eb7965fcbac6594f6

commit r13-2298-ga99b53f7e1860b96b67f069eb7965fcbac6594f6
Author: zhongjuzhe <juzhe.zhong@rivai.ai>
Date:   Tue Aug 23 15:06:31 2022 +0800

    middle-end: Fix unexpected warnings for RISC-V port.
    
    gcc/ChangeLog:
    
            * tree-vect-loop-manip.cc (vect_gen_vector_loop_niters): Simply
            initialize const_vf to 0.

Diff:
---
 gcc/tree-vect-loop-manip.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 86d2264054a..48a5f391d7f 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -1978,7 +1978,8 @@ vect_gen_vector_loop_niters (loop_vec_info loop_vinfo, tree niters,
   else
     ni_minus_gap = niters;
 
-  unsigned HOST_WIDE_INT const_vf;
+  /* To silence some unexpected warnings, simply initialize to 0. */
+  unsigned HOST_WIDE_INT const_vf = 0;
   if (vf.is_constant (&const_vf)
       && !LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
     {