r00/sfn: Fix copy propagation into buffer load address

A buffer load can not use an indirect register as address.

Fixes: 79ca456b48 ("r600/sfn: rewrite NIR backend")

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36488>

src/gallium/drivers/r600/sfn/sfn_instr_fetch.cpp

@@ -124,6 +124,8 @@ FetchInstr::replace_source(PRegister old_src, PVirtualValue new_src)
    bool success = false;
    auto new_reg = new_src->as_register();
    if (new_reg) {
+      if (!new_reg->has_flag(Register::ssa) && new_reg->addr())
+         return false;
       if (old_src->equal_to(*m_src)) {
          m_src->del_use(this);
          m_src = new_reg;