[backend]完善异步执行的超时切断机制

src/backend/RISCv64/RISCv64Backend.cpp

@@ -9,6 +9,9 @@
 #include <sstream>
 #include <future>
 #include <chrono>
+#include <atomic>
+#include <memory>
+#include <thread>
 #include <iostream>
 namespace sysy {
 
@@ -233,23 +236,46 @@ std::string RISCv64CodeGen::function_gen(Function* func) {
     scheduler.runOnMachineFunction(mfunc.get());
 
     // 阶段 3: 物理寄存器分配 (Register Allocation)
-
     bool allocation_succeeded = false;
+
     // 尝试迭代图着色 (IRC)
     if (!irc_failed) {
         if (DEBUG) std::cerr << "Attempting Register Allocation with Iterated Register Coloring (IRC)...\n";        
         RISCv64RegAlloc irc_alloc(mfunc.get());
-        if (irc_alloc.run()) {
+        auto stop_flag = std::make_shared<std::atomic<bool>>(false);
+        auto future = std::async(std::launch::async, &RISCv64RegAlloc::run, &irc_alloc, stop_flag);
+        std::future_status status = future.wait_for(std::chrono::seconds(25));
+        bool success_irc = false;
+        if (status == std::future_status::ready) {
+            try {
+                if (future.get()) {
+                    success_irc = true;
+                } else {
+                    std::cerr << "Warning: IRC explicitly returned failure for function '" << func->getName() << "'.\n";
+                }
+            } catch (const std::exception& e) {
+                std::cerr << "Error: IRC allocation threw an exception: " << e.what() << std::endl;
+            }
+        } else if (status == std::future_status::timeout) {
+            std::cerr << "Warning: IRC allocation timed out after 25 seconds. Requesting cancellation...\n";            
+            stop_flag->store(true);
+            try {
+                future.get();
+            } catch (const std::exception& e) {
+                std::cerr << "Exception occurred during IRC thread shutdown after timeout: " << e.what() << std::endl;
+            }
+        }
+
+        if (success_irc) {
             allocation_succeeded = true;
             if (DEBUG) std::cerr << "IRC allocation succeeded.\n";
         } else {
-            std::cerr << "Warning: IRC failed for function '" << func->getName() 
+            std::cerr << "Info: Blacklisting IRC for subsequent functions and falling back.\n";
-                    << "'. Blacklisting IRC for subsequent functions and falling back.\n";
+            irc_failed = true;
-            irc_failed = true; // 拉黑IRC，后续函数不再尝试
         }
     }
     
-    // 尝试简单图着色 (SGC) 并设置超时
+    // 尝试简单图着色 (SGC) 
     if (!allocation_succeeded) {
         // 如果是从IRC失败回退过来的，需要重新创建干净的mfunc和ISel
         RISCv64ISel isel_for_sgc;
@@ -266,7 +292,7 @@ std::string RISCv64CodeGen::function_gen(Function* func) {
         {
             RISCv64SimpleRegAlloc sgc_alloc(mfunc.get());
             auto future = std::async(std::launch::async, &RISCv64SimpleRegAlloc::run, &sgc_alloc);
-            std::future_status status = future.wait_for(std::chrono::seconds(20));
+            std::future_status status = future.wait_for(std::chrono::seconds(25));
 
             if (status == std::future_status::ready) {
                 try {
@@ -287,7 +313,7 @@ std::string RISCv64CodeGen::function_gen(Function* func) {
         }
     }
 
-    // 策略三：如果以上所有策略都失败了，则使用基本块分配器 (BBA)
+    // 如果都失败了，则使用基本块分配器 (BBA)
     if (!allocation_succeeded) {
         // 为BBA准备干净的mfunc和ISel
         std::cerr << "Info: Resetting MachineFunction for BBA fallback.\n";

src/backend/RISCv64/RISCv64RegAlloc.cpp

@@ -7,6 +7,7 @@
 #include <cassert>
 #include <chrono>
 #include <thread>
+#include <atomic>
 
 namespace sysy {
 
@@ -47,7 +48,7 @@ RISCv64RegAlloc::RISCv64RegAlloc(MachineFunction* mfunc)
 }
 
 // 主入口: 迭代运行分配算法直到无溢出
-bool RISCv64RegAlloc::run() {
+bool RISCv64RegAlloc::run(std::shared_ptr<std::atomic<bool>> stop_flag) {
     if (DEBUG) std::cerr << "===== LLIR Before Running Graph Coloring Register Allocation " << MFunc->getName() << " =====\n";
     std::stringstream ss_before_reg_alloc;
     if (DEBUG) {
@@ -68,6 +69,11 @@ bool RISCv64RegAlloc::run() {
             break;
         } else {
             rewriteProgram();
+            if (stop_flag && stop_flag->load()) {
+                // 如果从外部接收到停止信号
+                std::cerr << "Info: IRC allocation cancelled due to timeout.\n";
+                return false; // 提前退出，并返回失败
+            }
             if (DEBUG) std::cerr << "--- Spilling detected, re-running allocation (iteration " << iteration << ") ---\n";
             
             if (iteration >= MAX_ITERATIONS) {

src/include/backend/RISCv64/RISCv64RegAlloc.h

@@ -20,7 +20,7 @@ public:
     RISCv64RegAlloc(MachineFunction* mfunc);
 
     // 模块主入口
-    bool run();
+    bool run(std::shared_ptr<std::atomic<bool>> stop_flag);
 
 private:
     // 类型定义，与Python版本对应