Merge pull request #452 from sa-llo/lab6

[LAB6] 313704803

Author: YingMuo

lab6/llvm-pass.so.cc

@@ -13,9 +13,35 @@ PreservedAnalyses LLVMPass::run(Module &M, ModuleAnalysisManager &MAM) {
   IntegerType *Int32Ty = IntegerType::getInt32Ty(Ctx);
   FunctionCallee debug_func = M.getOrInsertFunction("debug", Int32Ty);
   ConstantInt *debug_arg = ConstantInt::get(Int32Ty, 48763);
+  PointerType *CharPtrTy = Type::getInt8PtrTy(Ctx);
+
+
 
   for (auto &F : M) {
-    errs() << "func: " << F.getName() << "\n";
+
+
+
+ // Find main function, call the debug function with argument 48763
+
+    if (F.getName() == "main"){
+    IRBuilder<> Builder(&*F.getEntryBlock().getFirstInsertionPt());
+    Builder.CreateCall(debug_func, {debug_arg});
+
+ // Overwrote argv1 with string "hayaku... motohayaku!"
+    Argument *argvArg = F.getArg(1);
+    Value *index1 = ConstantInt::get(Int32Ty, 1);
+    Value *argv1_ptr = Builder.CreateInBoundsGEP(CharPtrTy, argvArg, index1);
+    Value *hayakuStr = Builder.CreateGlobalStringPtr("hayaku... motohayaku!");
+    Builder.CreateStore(hayakuStr, argv1_ptr);
+
+ // Overwrote argcArg with 48763
+    Argument *argcArg = F.getArg(0);
+    argcArg -> replaceAllUsesWith(debug_arg);
+
+    }
+
+
+
 
   }
   return PreservedAnalyses::none();