minix/llvm/passes/hello/hello.cpp

   1 #include <pass.h>
   2 #include <stdlib.h>
   3
   4 using namespace llvm;
   5
   6 #define DBG(M) M
   7 #define helloPassLog(M) DBG(errs() << "HelloPass: " << M << "\n")
   8 #define MSG   "Hello world!"
   9 #define ERROR_FAILURE   1
  10
  11 namespace {
  12
  13   class HelloPass : public ModulePass {
  14
  15   public:
  16     static char ID;
  17
  18
  19     HelloPass() : ModulePass(ID) { }
  20
  21
  22     virtual bool runOnModule(Module &M) {
  23
  24     Function* printfFunction = NULL;
  25     Function* mainFunction = NULL;
  26
  27     mainFunction = M.getFunction("main");
  28     if (NULL == mainFunction)
  29     {
  30       helloPassLog("Info: main() not found. Skipping instrumentation.");
  31       return false;
  32     }
  33
  34     /* Prepare the string arguments for printf */
  35     std::string printFuncName = "printf" ;
  36     const std::string msg = MSG;
  37     const std::string fmt = "%s\n";
  38     Constant* strConstMsg = NULL;
  39     Constant* strConstFmt = NULL;
  40     std::vector<Value*> args(0);
  41     Instruction *I = NULL;
  42
  43     PassUtil::getStringGlobalVariable(M, fmt, ".fmtStr", "", &strConstFmt, false);
  44     PassUtil::getStringGlobalVariable(M, msg, ".helloworld", "", &strConstMsg, false);
  45
  46     if (NULL == strConstFmt || NULL == strConstMsg)
  47     {
  48           helloPassLog("Error: Prepared string contants point to NULL");
  49           exitOnError(ERROR_FAILURE);
  50     }
  51
  52     args.push_back(strConstFmt);
  53     args.push_back(strConstMsg);
  54
  55     /* Look for printf declaration */
  56     std::vector<TYPECONST Type*> functionTyArgs;
  57     FunctionType* printfFuncType;
  58
  59     functionTyArgs.push_back(PointerType::get(IntegerType::get(M.getContext(), 8), 0));
  60
  61     printfFuncType = PassUtil::getFunctionType(IntegerType::get(M.getContext(), 32), functionTyArgs, true);
  62     if (NULL == printfFuncType)
  63     {
  64       helloPassLog("Error: Couldn't make function-type for printf.");
  65       exitOnError(ERROR_FAILURE);
  66     }
  67
  68           printfFunction = (Function *) M.getOrInsertFunction(printFuncName, printfFuncType);
  69           if (NULL == printfFunction)
  70           {
  71       helloPassLog("Error: Couldnt find printf function declaration.");
  72       exitOnError(ERROR_FAILURE);
  73     }
  74
  75     /* Insert call instruction in main() to call printf */
  76           I = mainFunction->getBasicBlockList().begin()->begin();
  77           if (NULL != I)
  78           {
  79                   if (args.empty())
  80                   {
  81                           helloPassLog("Warning: args to printf is empty.");
  82                   }
  83
  84                   helloPassLog("Info: Inserting printf call instruction");
  85
  86                   CallInst* callInst = PassUtil::createCallInstruction(printfFunction, args, "", I);
  87
  88                   if (NULL == callInst )
  89                   {
  90                           helloPassLog("Error: callInstr is null.");
  91                           exitOnError(ERROR_FAILURE);
  92                   }
  93
  94                   helloPassLog("Info: Inserting call instruction successful.");
  95
  96                   return true;
  97           }
  98
  99       return false;
 100     }
 101
 102     private:
 103     void exitOnError(int errCode)
 104     {
 105       helloPassLog("Aborting instrumentation.");
 106         exit(errCode);
 107     }
 108
 109   };
 110
 111 }
 112
 113 char HelloPass::ID = 0;
 114 RegisterPass<HelloPass> HP("hello", "Hello Pass", false, false);