1 //===- MetaRenamer.cpp - Rename everything with metasyntatic names --------===//
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 pass renames everything with metasyntatic names. The intent is to use
11 // this pass after bugpoint reduction to conceal the nature of the original
12 // program.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "llvm/Transforms/IPO.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/IR/DerivedTypes.h"
20 #include "llvm/IR/Function.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/IR/Type.h"
23 #include "llvm/IR/TypeFinder.h"
24 #include "llvm/Pass.h"
25 using namespace llvm;
26
27 namespace {
28
29 // This PRNG is from the ISO C spec. It is intentionally simple and
30 // unsuitable for cryptographic use. We're just looking for enough
31 // variety to surprise and delight users.
32 struct PRNG {
33 unsigned long next;
34
srand__anon4cba1af80111::PRNG35 void srand(unsigned int seed) {
36 next = seed;
37 }
38
rand__anon4cba1af80111::PRNG39 int rand() {
40 next = next * 1103515245 + 12345;
41 return (unsigned int)(next / 65536) % 32768;
42 }
43 };
44
45 struct MetaRenamer : public ModulePass {
46 static char ID; // Pass identification, replacement for typeid
MetaRenamer__anon4cba1af80111::MetaRenamer47 MetaRenamer() : ModulePass(ID) {
48 initializeMetaRenamerPass(*PassRegistry::getPassRegistry());
49 }
50
getAnalysisUsage__anon4cba1af80111::MetaRenamer51 void getAnalysisUsage(AnalysisUsage &AU) const override {
52 AU.setPreservesAll();
53 }
54
runOnModule__anon4cba1af80111::MetaRenamer55 bool runOnModule(Module &M) override {
56 static const char *const metaNames[] = {
57 // See http://en.wikipedia.org/wiki/Metasyntactic_variable
58 "foo", "bar", "baz", "quux", "barney", "snork", "zot", "blam", "hoge",
59 "wibble", "wobble", "widget", "wombat", "ham", "eggs", "pluto", "spam"
60 };
61
62 // Seed our PRNG with simple additive sum of ModuleID. We're looking to
63 // simply avoid always having the same function names, and we need to
64 // remain deterministic.
65 unsigned int randSeed = 0;
66 for (std::string::const_iterator I = M.getModuleIdentifier().begin(),
67 E = M.getModuleIdentifier().end(); I != E; ++I)
68 randSeed += *I;
69
70 PRNG prng;
71 prng.srand(randSeed);
72
73 // Rename all aliases
74 for (Module::alias_iterator AI = M.alias_begin(), AE = M.alias_end();
75 AI != AE; ++AI) {
76 StringRef Name = AI->getName();
77 if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
78 continue;
79
80 AI->setName("alias");
81 }
82
83 // Rename all global variables
84 for (Module::global_iterator GI = M.global_begin(), GE = M.global_end();
85 GI != GE; ++GI) {
86 StringRef Name = GI->getName();
87 if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
88 continue;
89
90 GI->setName("global");
91 }
92
93 // Rename all struct types
94 TypeFinder StructTypes;
95 StructTypes.run(M, true);
96 for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
97 StructType *STy = StructTypes[i];
98 if (STy->isLiteral() || STy->getName().empty()) continue;
99
100 SmallString<128> NameStorage;
101 STy->setName((Twine("struct.") + metaNames[prng.rand() %
102 array_lengthof(metaNames)]).toStringRef(NameStorage));
103 }
104
105 // Rename all functions
106 for (Module::iterator FI = M.begin(), FE = M.end();
107 FI != FE; ++FI) {
108 StringRef Name = FI->getName();
109 if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
110 continue;
111
112 FI->setName(metaNames[prng.rand() % array_lengthof(metaNames)]);
113 runOnFunction(*FI);
114 }
115 return true;
116 }
117
runOnFunction__anon4cba1af80111::MetaRenamer118 bool runOnFunction(Function &F) {
119 for (Function::arg_iterator AI = F.arg_begin(), AE = F.arg_end();
120 AI != AE; ++AI)
121 if (!AI->getType()->isVoidTy())
122 AI->setName("arg");
123
124 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
125 BB->setName("bb");
126
127 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
128 if (!I->getType()->isVoidTy())
129 I->setName("tmp");
130 }
131 return true;
132 }
133 };
134 }
135
136 char MetaRenamer::ID = 0;
137 INITIALIZE_PASS(MetaRenamer, "metarenamer",
138 "Assign new names to everything", false, false)
139 //===----------------------------------------------------------------------===//
140 //
141 // MetaRenamer - Rename everything with metasyntactic names.
142 //
createMetaRenamerPass()143 ModulePass *llvm::createMetaRenamerPass() {
144 return new MetaRenamer();
145 }
146