diff --git a/src/backend/RISCv64/RISCv64LinearScan.cpp b/src/backend/RISCv64/RISCv64LinearScan.cpp
index 1857281..9061cd8 100644
--- a/src/backend/RISCv64/RISCv64LinearScan.cpp
+++ b/src/backend/RISCv64/RISCv64LinearScan.cpp
@@ -73,7 +73,7 @@ RISCv64LinearScan::RISCv64LinearScan(MachineFunction* mfunc)
     
     allocable_int_regs = {
         PhysicalReg::T0, PhysicalReg::T1, PhysicalReg::T2, PhysicalReg::T3, PhysicalReg::T4, PhysicalReg::T6,
-        PhysicalReg::A0, PhysicalReg::A1, PhysicalReg::A2, PhysicalReg::A3, PhysicalReg::A4, PhysicalReg::A5, PhysicalReg::A6, PhysicalReg::A7,
+        // PhysicalReg::A0, PhysicalReg::A1, PhysicalReg::A2, PhysicalReg::A3, PhysicalReg::A4, PhysicalReg::A5, PhysicalReg::A6, PhysicalReg::A7,
         PhysicalReg::S1, PhysicalReg::S2, PhysicalReg::S3, PhysicalReg::S4, PhysicalReg::S5, PhysicalReg::S6, PhysicalReg::S7,
         PhysicalReg::S8, PhysicalReg::S9, PhysicalReg::S10, PhysicalReg::S11,
     };
@@ -159,7 +159,7 @@ void RISCv64LinearScan::computeLiveIntervals() {
         }
     }
 
-    // b. 活跃变量分析（数据流分析部分）
+    // b. 活跃变量分析（数据流分析部分，这部分是正确的，保持不变）
     if (DEEPDEBUG) std::cerr << "  [Live] Starting live variable dataflow analysis...\n";
     std::map<const MachineBasicBlock*, std::set<unsigned>> live_in, live_out;
     bool changed = true;
@@ -198,44 +198,49 @@ void RISCv64LinearScan::computeLiveIntervals() {
 
     // c. 根据指令遍历和活跃出口信息，精确构建区间
     if (DEEPDEBUG) std::cerr << "  [Live] Building precise intervals...\n";
-    std::map<unsigned, int> first_occurrence, last_occurrence;
+    std::map<unsigned, int> first_def, last_use;
 
+    // 步骤 c.1: 遍历所有指令，找到每个vreg的首次定义和最后一次使用
     for (auto* mbb : linear_order_blocks) {
         for (auto& instr_ptr : mbb->getInstructions()) {
             int instr_num = instr_numbering.at(instr_ptr.get());
             std::set<unsigned> use, def;
             getInstrUseDef(instr_ptr.get(), use, def);
-            
-            std::set<unsigned> all_vregs = use;
-            all_vregs.insert(def.begin(), def.end());
 
-            for (unsigned vreg : all_vregs) {
-                if (first_occurrence.find(vreg) == first_occurrence.end()) {
-                    first_occurrence[vreg] = instr_num;
+            for (unsigned vreg : def) {
+                if (first_def.find(vreg) == first_def.end()) {
+                    first_def[vreg] = instr_num;
                 }
-                last_occurrence[vreg] = instr_num;
+            }
+            for (unsigned vreg : use) {
+                last_use[vreg] = instr_num;
             }
         }
     }
     
-    // 使用 live_out 信息修正区间的结束点
+    // 步骤 c.2: 创建 LiveInterval 对象，并使用 live_out 信息修正区间的结束点
+    for (auto const& [vreg, start] : first_def) {
+        live_intervals.emplace(vreg, LiveInterval(vreg));
+        auto& interval = live_intervals.at(vreg);
+        interval.start = start;
+        
+        // 初始结束点是最后一次使用。如果从未被使用，则结束点就是定义点。
+        interval.end = last_use.count(vreg) ? last_use.at(vreg) : start;
+    }
+
     for (auto const& [mbb, live_set] : live_out) {
         if (mbb->getInstructions().empty()) continue;
         int block_end_num = instr_numbering.at(mbb->getInstructions().back().get());
         for (unsigned vreg : live_set) {
-            if (last_occurrence.count(vreg)) {
-                last_occurrence[vreg] = std::max(last_occurrence[vreg], block_end_num);
+            if (live_intervals.count(vreg)) {
+                live_intervals.at(vreg).end = std::max(live_intervals.at(vreg).end, block_end_num);
             }
         }
     }
     
-    // 创建最终的 LiveInterval 对象
-    for (auto const& [vreg, start] : first_occurrence) {
-        live_intervals.emplace(vreg, LiveInterval(vreg));
-        auto& interval = live_intervals.at(vreg);
-        interval.start = start;
-        interval.end = last_occurrence.at(vreg);
-        
+    // 步骤 c.3: 检查是否跨越函数调用
+    for (auto& pair : live_intervals) {
+        auto& interval = pair.second;
         auto it = call_locations.lower_bound(interval.start);
         if (it != call_locations.end() && *it < interval.end) {
             interval.crosses_call = true;
diff --git a/src/backend/RISCv64/RISCv64RegAlloc.cpp b/src/backend/RISCv64/RISCv64RegAlloc.cpp
index f7d364f..c09bd5d 100644
--- a/src/backend/RISCv64/RISCv64RegAlloc.cpp
+++ b/src/backend/RISCv64/RISCv64RegAlloc.cpp
@@ -65,6 +65,44 @@ void RISCv64RegAlloc::run() {
         }
     }
 
+    // const int MAX_ITERATIONS = 50;
+    // int iteration = 0;
+    
+    // while (iteration++ < MAX_ITERATIONS) {
+    //     if (doAllocation()) {
+    //         break;
+    //     } else {
+    //         rewriteProgram();
+    //         if (DEBUG) std::cerr << "--- Spilling detected, re-running allocation (iteration " << iteration << ") ---\n";
+            
+    //         if (iteration >= MAX_ITERATIONS) {
+    //             std::cerr << "ERROR: Register allocation failed to converge after " << MAX_ITERATIONS << " iterations\n";
+    //             std::cerr << "  Spill worklist size: " << spillWorklist.size() << "\n";
+    //             std::cerr << "  Total nodes: " << (initial.size() + coloredNodes.size()) << "\n";
+                
+    //             // Emergency spill remaining nodes to break the loop
+    //             std::cerr << "  Emergency spilling remaining spill worklist nodes...\n";
+    //             for (unsigned node : spillWorklist) {
+    //                 spilledNodes.insert(node);
+    //             }
+                
+    //             // Also spill any nodes that didn't get colors
+    //             std::set<unsigned> uncolored;
+    //             for (unsigned node : initial) {
+    //                 if (color_map.find(node) == color_map.end()) {
+    //                     uncolored.insert(node);
+    //                 }
+    //             }
+    //             for (unsigned node : uncolored) {
+    //                 spilledNodes.insert(node);
+    //             }
+                
+    //             // Force completion
+    //             break;
+    //         }
+    //     }
+    // }
+
     applyColoring();
     
     MFunc->getFrameInfo().vreg_to_preg_map = this->color_map;