[backend]修复了溢出位置错误的问题

src/backend/RISCv64/RISCv64RegAlloc.cpp

@@ -656,7 +656,7 @@ void RISCv64RegAlloc::rewriteProgram() {
     StackFrameInfo& frame_info = MFunc->getFrameInfo();
     // 使用 EFI Pass 确定的 locals_end_offset 作为溢出分配的基准。
     // locals_end_offset 本身是负数，代表局部变量区域的下边界地址。
-    int spill_current_offset = frame_info.locals_end_offset;
+    int spill_current_offset = frame_info.locals_end_offset - frame_info.spill_size;
 
     // 保存溢出区域的起始点，用于最后计算总的 spill_size
     const int spill_start_offset = frame_info.locals_end_offset;
@@ -787,6 +787,11 @@ void RISCv64RegAlloc::rewriteProgram() {
                     std::make_unique<ImmOperand>(frame_info.spill_offsets.at(old_vreg))
                 ));
                 new_instructions.push_back(std::move(store));
+                if (DEEPERDEBUG) {
+                    std::cerr << "[Spill] Inserted spill store for %vreg" << old_vreg 
+                              << " at offset " << frame_info.spill_offsets.at(old_vreg) 
+                              << " with new temp vreg " << regIdToString(new_temp_vreg) << ".\n";
+                }
             }
         }
         mbb->getInstructions() = std::move(new_instructions);