lib/Transforms/Hello/Hello.cpp

   1 //===- Hello.cpp - Example code from "Writing an LLVM Pass" ---------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements two versions of the LLVM "Hello World" pass described
  11 // in docs/WritingAnLLVMPass.html
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Pass.h"
  16 #include "llvm/Function.h"
  17 #include "llvm/ADT/StringExtras.h"
  18 #include "llvm/Support/SlowOperationInformer.h"
  19 #include "llvm/ADT/Statistic.h"
  20 #include <iostream>
  21 using namespace llvm;
  22
  23 namespace {
  24   Statistic<int> HelloCounter("hellocount",
  25       "Counts number of functions greeted");
  26   // Hello - The first implementation, without getAnalysisUsage.
  27   struct Hello : public FunctionPass {
  28     virtual bool runOnFunction(Function &F) {
  29       SlowOperationInformer soi("EscapeString");
  30       HelloCounter++;
  31       std::string fname = F.getName();
  32       EscapeString(fname);
  33       std::cerr << "Hello: " << fname << "\n";
  34       return false;
  35     }
  36   };
  37   RegisterOpt<Hello> X("hello", "Hello World Pass");
  38
  39   // Hello2 - The second implementation with getAnalysisUsage implemented.
  40   struct Hello2 : public FunctionPass {
  41     virtual bool runOnFunction(Function &F) {
  42       SlowOperationInformer soi("EscapeString");
  43       HelloCounter++;
  44       std::string fname = F.getName();
  45       EscapeString(fname);
  46       std::cerr << "Hello: " << fname << "\n";
  47       return false;
  48     }
  49
  50     // We don't modify the program, so we preserve all analyses
  51     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
  52       AU.setPreservesAll();
  53     };
  54   };
  55   RegisterOpt<Hello2> Y("hello2", "Hello World Pass (with getAnalysisUsage implemented)");
  56 }