Home | History | Annotate | Download | only in Hello
      1 //===- Hello.cpp - Example code from "Writing an LLVM Pass" ---------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // 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 #define DEBUG_TYPE "hello"
     16 #include "llvm/ADT/Statistic.h"
     17 #include "llvm/IR/Function.h"
     18 #include "llvm/Pass.h"
     19 #include "llvm/Support/raw_ostream.h"
     20 using namespace llvm;
     21 
     22 STATISTIC(HelloCounter, "Counts number of functions greeted");
     23 
     24 namespace {
     25   // Hello - The first implementation, without getAnalysisUsage.
     26   struct Hello : public FunctionPass {
     27     static char ID; // Pass identification, replacement for typeid
     28     Hello() : FunctionPass(ID) {}
     29 
     30     virtual bool runOnFunction(Function &F) {
     31       ++HelloCounter;
     32       errs() << "Hello: ";
     33       errs().write_escaped(F.getName()) << '\n';
     34       return false;
     35     }
     36   };
     37 }
     38 
     39 char Hello::ID = 0;
     40 static RegisterPass<Hello> X("hello", "Hello World Pass");
     41 
     42 namespace {
     43   // Hello2 - The second implementation with getAnalysisUsage implemented.
     44   struct Hello2 : public FunctionPass {
     45     static char ID; // Pass identification, replacement for typeid
     46     Hello2() : FunctionPass(ID) {}
     47 
     48     virtual bool runOnFunction(Function &F) {
     49       ++HelloCounter;
     50       errs() << "Hello: ";
     51       errs().write_escaped(F.getName()) << '\n';
     52       return false;
     53     }
     54 
     55     // We don't modify the program, so we preserve all analyses
     56     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
     57       AU.setPreservesAll();
     58     }
     59   };
     60 }
     61 
     62 char Hello2::ID = 0;
     63 static RegisterPass<Hello2>
     64 Y("hello2", "Hello World Pass (with getAnalysisUsage implemented)");
     65