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 #include "llvm/ADT/Statistic.h" 16 #include "llvm/IR/Function.h" 17 #include "llvm/Pass.h" 18 #include "llvm/Support/raw_ostream.h" 19 using namespace llvm; 20 21 #define DEBUG_TYPE "hello" 22 23 STATISTIC(HelloCounter, "Counts number of functions greeted"); 24 25 namespace { 26 // Hello - The first implementation, without getAnalysisUsage. 27 struct Hello : public FunctionPass { 28 static char ID; // Pass identification, replacement for typeid 29 Hello() : FunctionPass(ID) {} 30 31 bool runOnFunction(Function &F) override { 32 ++HelloCounter; 33 errs() << "Hello: "; 34 errs().write_escaped(F.getName()) << '\n'; 35 return false; 36 } 37 }; 38 } 39 40 char Hello::ID = 0; 41 static RegisterPass<Hello> X("hello", "Hello World Pass"); 42 43 namespace { 44 // Hello2 - The second implementation with getAnalysisUsage implemented. 45 struct Hello2 : public FunctionPass { 46 static char ID; // Pass identification, replacement for typeid 47 Hello2() : FunctionPass(ID) {} 48 49 bool runOnFunction(Function &F) override { 50 ++HelloCounter; 51 errs() << "Hello: "; 52 errs().write_escaped(F.getName()) << '\n'; 53 return false; 54 } 55 56 // We don't modify the program, so we preserve all analyses. 57 void getAnalysisUsage(AnalysisUsage &AU) const override { 58 AU.setPreservesAll(); 59 } 60 }; 61 } 62 63 char Hello2::ID = 0; 64 static RegisterPass<Hello2> 65 Y("hello2", "Hello World Pass (with getAnalysisUsage implemented)"); 66
