[backend]回溯了旧版本的寄存器分配器

src/backend/RISCv64/CMakeLists.txt

@@ -6,6 +6,7 @@ add_library(riscv64_backend_lib STATIC
     RISCv64LLIR.cpp
     RISCv64RegAlloc.cpp
     RISCv64LinearScan.cpp
+    RISCv64SimpleRegAlloc.cpp
     RISCv64BasicBlockAlloc.cpp
     Handler/CalleeSavedHandler.cpp
     Handler/LegalizeImmediates.cpp