1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
//===- MetaRenamer.cpp - Rename everything with metasyntatic names --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This pass renames everything with metasyntatic names. The intent is to use
// this pass after bugpoint reduction to conceal the nature of the original
// program.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/TypeFinder.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils.h"
using namespace llvm;
static const char *const metaNames[] = {
// See http://en.wikipedia.org/wiki/Metasyntactic_variable
"foo", "bar", "baz", "quux", "barney", "snork", "zot", "blam", "hoge",
"wibble", "wobble", "widget", "wombat", "ham", "eggs", "pluto", "spam"
};
namespace {
// This PRNG is from the ISO C spec. It is intentionally simple and
// unsuitable for cryptographic use. We're just looking for enough
// variety to surprise and delight users.
struct PRNG {
unsigned long next;
void srand(unsigned int seed) {
next = seed;
}
int rand() {
next = next * 1103515245 + 12345;
return (unsigned int)(next / 65536) % 32768;
}
};
struct Renamer {
Renamer(unsigned int seed) {
prng.srand(seed);
}
const char *newName() {
return metaNames[prng.rand() % array_lengthof(metaNames)];
}
PRNG prng;
};
struct MetaRenamer : public ModulePass {
// Pass identification, replacement for typeid
static char ID;
MetaRenamer() : ModulePass(ID) {
initializeMetaRenamerPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.setPreservesAll();
}
bool runOnModule(Module &M) override {
// Seed our PRNG with simple additive sum of ModuleID. We're looking to
// simply avoid always having the same function names, and we need to
// remain deterministic.
unsigned int randSeed = 0;
for (auto C : M.getModuleIdentifier())
randSeed += C;
Renamer renamer(randSeed);
// Rename all aliases
for (auto AI = M.alias_begin(), AE = M.alias_end(); AI != AE; ++AI) {
StringRef Name = AI->getName();
if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
continue;
AI->setName("alias");
}
// Rename all global variables
for (auto GI = M.global_begin(), GE = M.global_end(); GI != GE; ++GI) {
StringRef Name = GI->getName();
if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
continue;
GI->setName("global");
}
// Rename all struct types
TypeFinder StructTypes;
StructTypes.run(M, true);
for (StructType *STy : StructTypes) {
if (STy->isLiteral() || STy->getName().empty()) continue;
SmallString<128> NameStorage;
STy->setName((Twine("struct.") +
renamer.newName()).toStringRef(NameStorage));
}
// Rename all functions
const TargetLibraryInfo &TLI =
getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
for (auto &F : M) {
StringRef Name = F.getName();
LibFunc Tmp;
// Leave library functions alone because their presence or absence could
// affect the behavior of other passes.
if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1) ||
TLI.getLibFunc(F, Tmp))
continue;
// Leave @main alone. The output of -metarenamer might be passed to
// lli for execution and the latter needs a main entry point.
if (Name != "main")
F.setName(renamer.newName());
runOnFunction(F);
}
return true;
}
bool runOnFunction(Function &F) {
for (auto AI = F.arg_begin(), AE = F.arg_end(); AI != AE; ++AI)
if (!AI->getType()->isVoidTy())
AI->setName("arg");
for (auto &BB : F) {
BB.setName("bb");
for (auto &I : BB)
if (!I.getType()->isVoidTy())
I.setName("tmp");
}
return true;
}
};
} // end anonymous namespace
char MetaRenamer::ID = 0;
INITIALIZE_PASS_BEGIN(MetaRenamer, "metarenamer",
"Assign new names to everything", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(MetaRenamer, "metarenamer",
"Assign new names to everything", false, false)
//===----------------------------------------------------------------------===//
//
// MetaRenamer - Rename everything with metasyntactic names.
//
ModulePass *llvm::createMetaRenamerPass() {
return new MetaRenamer();
}
|
