[LAB6] 313554033

lab6/llvm-pass.so.cc

@@ -1,34 +1,112 @@
+// llvm-pass.so.cc
 #include "llvm/Passes/PassPlugin.h"
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/IR/IRBuilder.h"
-
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Constants.h"
+#include <vector>
 using namespace llvm;
 
-struct LLVMPass : public PassInfoMixin<LLVMPass> {
-  PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
-};
+struct LLVMPass : PassInfoMixin<LLVMPass> {
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &) {
+    LLVMContext &Ctx    = M.getContext();
+    IntegerType *i32Ty  = Type::getInt32Ty(Ctx);
+    PointerType *i8PtrTy= Type::getInt8PtrTy(Ctx);
+
+    // 1) debug(int)
+    FunctionCallee debugFn = M.getOrInsertFunction(
+      "debug",
+      FunctionType::get(Type::getVoidTy(Ctx), {i32Ty}, false)
+    );
+    Constant *debugArg = ConstantInt::get(i32Ty, 48763);
+
+    // 2) 準備常量字串
+    Constant *strData = ConstantDataArray::getString(
+      Ctx, "hayaku... motohayaku!", true);
+    GlobalVariable *gvStr = new GlobalVariable(
+      M, strData->getType(), true,
+      GlobalValue::PrivateLinkage, strData, "lab6_str");
+    Value *strPtr = ConstantExpr::getBitCast(gvStr, i8PtrTy);
+
+    // 找 main 函式
+    if (Function *mainF = M.getFunction("main")) {
+      // 在 EntryBlock 首個插入點呼叫 debug(48763)
+      IRBuilder<> B(&*mainF->getEntryBlock().getFirstInsertionPt());
+      B.CreateCall(debugFn, { debugArg });
+
+      // 取出 main(argc, argv) 的參數
+      Argument *argcArg = nullptr, *argvArg = nullptr;
+      auto it = mainF->arg_begin();
+      if (it != mainF->arg_end()) argcArg = &*it++;
+      if (it != mainF->arg_end()) argvArg = &*it;
+
+      // 搜集所有要移除的 LoadInst
+      std::vector<Instruction*> toErase;
 
-PreservedAnalyses LLVMPass::run(Module &M, ModuleAnalysisManager &MAM) {
-  LLVMContext &Ctx = M.getContext();
-  IntegerType *Int32Ty = IntegerType::getInt32Ty(Ctx);
-  FunctionCallee debug_func = M.getOrInsertFunction("debug", Int32Ty);
-  ConstantInt *debug_arg = ConstantInt::get(Int32Ty, 48763);
+      // 遍历所有指令
+      for (auto &BB : *mainF) {
+        for (auto &I : BB) {
+          // (a) 替换所有使用 argcArg 的地方
+          for (unsigned u = 0; u < I.getNumOperands(); ++u) {
+            if (I.getOperand(u) == argcArg)
+              I.setOperand(u, debugArg);
+          }
 
-  for (auto &F : M) {
-    errs() << "func: " << F.getName() << "\n";
+          // (b) 找到 load argv[1] 的 LoadInst，替换它的所有使用
 
+          if (auto *LI = dyn_cast<LoadInst>(&I)) {
+                        // 把所有 index==1 的 GEP 载入都替换
+                        Value *ptr = LI->getPointerOperand()->stripPointerCasts();
+                        if (auto *G = dyn_cast<GetElementPtrInst>(ptr)) {
+                          if (G->getNumIndices() == 1) {
+                            if (auto *CI = dyn_cast<ConstantInt>(G->getOperand(1))) {
+                              if (CI->equalsInt(1)) {
+                                LI->replaceAllUsesWith(strPtr);
+                                toErase.push_back(LI);
+                              }
+                            }
+                          }
+                        }
+                      }
+
+          // (c) 用 arg_size() 替换 strcmp 的第一個參數
+          if (auto *CI = dyn_cast<CallInst>(&I)) {
+            if (Function *callee = CI->getCalledFunction()) {
+              if (callee->getName() == "strcmp" && CI->arg_size() >= 2) {
+                CI->setArgOperand(0, strPtr);
+              }
+            }
+          }
+        }
+      }
+
+      // 真正刪除那些已被替換的 LoadInst
+      for (auto *I : toErase)
+        I->eraseFromParent();
+    }
+
+    return PreservedAnalyses::none();
   }
-  return PreservedAnalyses::none();
-}
+};
 
+// 註冊為 LLVM Plugin
 extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
 llvmGetPassPluginInfo() {
-  return {LLVM_PLUGIN_API_VERSION, "LLVMPass", "1.0",
+  return {
+    LLVM_PLUGIN_API_VERSION, "Lab6Pass", "v1.0",
     [](PassBuilder &PB) {
-      PB.registerOptimizerLastEPCallback(
-        [](ModulePassManager &MPM, OptimizationLevel OL) {
+    //   PB.registerOptimizerLastEPCallback(
+    //     [](ModulePassManager &MPM, OptimizationLevel) {
+    //       MPM.addPass(LLVMPass());
+    //     });
+    // }
+     // 無論 -O0 還是 -O1/O2，都在 pipeline 一開始插入 LLVMPass
+      PB.registerPipelineStartEPCallback(
+        [](ModulePassManager &MPM, OptimizationLevel) {
           MPM.addPass(LLVMPass());
-        });
-    }};
+      });
+    }
+  };
 }
-