Merge pull request #437 from wei020789/lab6

[LAB6] 313553053

Author: YingMuo

lab6/llvm-pass.so.cc

@@ -1,26 +1,99 @@
 #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);
-};
+// 定義一個 Module Pass
+struct LLVMPass : PassInfoMixin<LLVMPass> {
+    PreservedAnalyses run(Module &Mod, ModuleAnalysisManager &) {
+        LLVMContext &Context = Mod.getContext();
+        IntegerType *int32Type = Type::getInt32Ty(Context);
+        PointerType *charPtrType = Type::getInt8PtrTy(Context);
 
-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);
+        // 宣告 debug 函數原型：void debug(int)
+        FunctionCallee dbgFunc = Mod.getOrInsertFunction(
+            "debug",
+            FunctionType::get(Type::getVoidTy(Context), {int32Type}, false)
+        );
+        // 常數 48763
+        Constant *const48763 = ConstantInt::get(int32Type, 48763);
 
-  for (auto &F : M) {
-    errs() << "func: " << F.getName() << "\n";
+        // 準備字串 "hayaku... motohayaku!"
+        Constant *msgContent = ConstantDataArray::getString(Context, "hayaku... motohayaku!", true);
+        GlobalVariable *globalMsg = new GlobalVariable(
+            Mod, msgContent->getType(), true,
+            GlobalValue::PrivateLinkage, msgContent, "lab6_message");
+        Value *msgPtr = ConstantExpr::getBitCast(globalMsg, charPtrType);
 
-  }
-  return PreservedAnalyses::none();
-}
+        // 處理 main 函數
+        if (Function *mainFunc = Mod.getFunction("main")) {
+            // 找到 argc, argv
+            Argument *argArgc = nullptr, *argArgv = nullptr;
+            auto iter = mainFunc->arg_begin();
+            if (iter != mainFunc->arg_end()) argArgc = &*iter++;
+            if (iter != mainFunc->arg_end()) argArgv = &*iter;
+
+            // 先把 debug 呼叫插入 main 開頭
+            IRBuilder<> builder(&*mainFunc->getEntryBlock().getFirstInsertionPt());
+            builder.CreateCall(dbgFunc, { const48763 });
+
+            // 用來記錄稍後要刪除的 load 指令
+            std::vector<Instruction*> removeList;
+
+            // 逐個基本區塊與指令掃描
+            for (auto &block : *mainFunc) {
+                for (auto &inst : block) {
+                    // 替換對 argc 的引用為 48763
+                    for (unsigned idx = 0; idx < inst.getNumOperands(); ++idx) {
+                        if (inst.getOperand(idx) == argArgc) {
+                            inst.setOperand(idx, const48763);
+                        }
+                    }
+
+                    // 處理 load 指令（找 argv[1]）
+                    if (auto *loadInst = dyn_cast<LoadInst>(&inst)) {
+                        Value *gepSource = loadInst->getPointerOperand()->stripPointerCasts();
+                        if (auto *gepInst = dyn_cast<GetElementPtrInst>(gepSource)) {
+                            if (gepInst->getNumIndices() == 1) {
+                                if (auto *constIdx = dyn_cast<ConstantInt>(gepInst->getOperand(1))) {
+                                    if (constIdx->equalsInt(1)) {
+                                        // 替換 load argv[1] 為常數字串
+                                        loadInst->replaceAllUsesWith(msgPtr);
+                                        removeList.push_back(loadInst);
+                                    }
+                                }
+                            }
+                        }
+                    }
 
+                    // 找 strcmp 呼叫，把第一個參數換成常數字串
+                    if (auto *callInst = dyn_cast<CallInst>(&inst)) {
+                        if (Function *calleeFunc = callInst->getCalledFunction()) {
+                            if (calleeFunc->getName() == "strcmp" && callInst->arg_size() >= 2) {
+                                callInst->setArgOperand(0, msgPtr);
+                            }
+                        }
+                    }
+                }
+            }
+
+            // 刪掉被替換的 load 指令
+            for (auto *instToErase : removeList) {
+                instToErase->eraseFromParent();
+            }
+        }
+
+        return PreservedAnalyses::none();
+    }
+};
+
+// 註冊這個 pass
 extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
 llvmGetPassPluginInfo() {
   return {LLVM_PLUGIN_API_VERSION, "LLVMPass", "1.0",
@@ -31,4 +104,3 @@ llvmGetPassPluginInfo() {
         });
     }};
 }
-