From 7ad2138ab6a9e61b84575f4f41762778cc7e0ad4 Mon Sep 17 00:00:00 2001
From: Bar Soloveychik <barsolo@fb.com>
Date: Thu, 30 Oct 2025 16:07:24 -0700
Subject: [PATCH] Adding vlenb register as callee register

---
 lldb/source/Plugins/ABI/RISCV/ABISysV_riscv.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lldb/source/Plugins/ABI/RISCV/ABISysV_riscv.cpp b/lldb/source/Plugins/ABI/RISCV/ABISysV_riscv.cpp
index b313ca03fb970..d46593358ba6d 100644
--- a/lldb/source/Plugins/ABI/RISCV/ABISysV_riscv.cpp
+++ b/lldb/source/Plugins/ABI/RISCV/ABISysV_riscv.cpp
@@ -798,6 +798,8 @@ bool ABISysV_riscv::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {
           // floating point hardware names
           .Cases("f8", "f9", "f18", "f19", "f20", "f21", "f22", "f23", is_hw_fp)
           .Cases("f24", "f25", "f26", "f27", is_hw_fp)
+          // vlenb is constant and needed for vector unwinding.
+          .Case("vlenb", true)
           .Default(false);
 
   return is_callee_saved;