[gcc(refs/vendors/riscv/heads/gcc-13-with-riscv-opts)] RISC-V: Fix one warning of maybe-uninitialized in riscv-vsetvl.cc

[Jeff Law]

https://gcc.gnu.org/g:63e7c34efd4e50b1f256e2c0ad1220abfba92b78

commit 63e7c34efd4e50b1f256e2c0ad1220abfba92b78
Author: Pan Li <pan2.li@intel.com>
Date:   Fri Jun 16 19:31:15 2023 +0800

    RISC-V: Fix one warning of maybe-uninitialized in riscv-vsetvl.cc
    
    This patch would like to fix one maybe-uninitialized warning. Aka:
    
    riscv-vsetvl.cc:4354:3: error: 'vsetvl_rinsn' may be used uninitialized [-Werror=maybe-uninitialized]
    
    Signed-off-by: Pan Li <pan2.li@intel.com>
    
    gcc/ChangeLog:
    
            * config/riscv/riscv-vsetvl.cc
            (pass_vsetvl::global_eliminate_vsetvl_insn): Initialize var by NULL.

Diff:
---
 gcc/config/riscv/riscv-vsetvl.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index cae9be0d928..7066dea3d14 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -4340,7 +4340,7 @@ get_first_vsetvl_before_rvv_insns (basic_block cfg_bb)
 bool
 pass_vsetvl::global_eliminate_vsetvl_insn (const bb_info *bb) const
 {
-  rtx_insn *vsetvl_rinsn;
+  rtx_insn *vsetvl_rinsn = NULL;
   vector_insn_info dem = vector_insn_info ();
   const auto &block_info = get_block_info (bb);
   basic_block cfg_bb = bb->cfg_bb ();