1 | //===- Hello.cpp - Example code from "Writing an LLVM Pass" ---------------===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file implements two versions of the LLVM "Hello World" pass described |
10 | // in docs/WritingAnLLVMPass.html |
11 | // |
12 | //===----------------------------------------------------------------------===// |
13 | |
14 | #include "llvm/ADT/Statistic.h" |
15 | #include "llvm/IR/Function.h" |
16 | #include "llvm/Pass.h" |
17 | #include "llvm/Support/raw_ostream.h" |
18 | using namespace llvm; |
19 | |
20 | #define DEBUG_TYPE "hello" |
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 | bool runOnFunction(Function &F) override { |
31 | ++HelloCounter; |
32 | errs() << "Hello: " ; |
33 | errs().write_escaped(Str: 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 | bool runOnFunction(Function &F) override { |
49 | ++HelloCounter; |
50 | errs() << "Hello: " ; |
51 | errs().write_escaped(Str: F.getName()) << '\n'; |
52 | return false; |
53 | } |
54 | |
55 | // We don't modify the program, so we preserve all analyses. |
56 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
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 | |