1 //==-- handle_llvm.cpp - Helper function for Clang fuzzers -----------------==//
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 // Implements HandleLLVM for use by the Clang fuzzers. First runs a loop
10 // vectorizer optimization pass over the given IR code. Then mimics lli on both
11 // versions to JIT the generated code and execute it. Currently, functions are
12 // executed on dummy inputs.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "handle_llvm.h"
17 #include "input_arrays.h"
18
19 #include "llvm/ADT/Triple.h"
20 #include "llvm/Analysis/TargetLibraryInfo.h"
21 #include "llvm/Analysis/TargetTransformInfo.h"
22 #include "llvm/CodeGen/CommandFlags.h"
23 #include "llvm/CodeGen/MachineModuleInfo.h"
24 #include "llvm/CodeGen/TargetPassConfig.h"
25 #include "llvm/ExecutionEngine/JITEventListener.h"
26 #include "llvm/ExecutionEngine/JITSymbol.h"
27 #include "llvm/ExecutionEngine/MCJIT.h"
28 #include "llvm/ExecutionEngine/ObjectCache.h"
29 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
30 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
31 #include "llvm/IR/IRPrintingPasses.h"
32 #include "llvm/IR/LLVMContext.h"
33 #include "llvm/IR/LegacyPassManager.h"
34 #include "llvm/IR/LegacyPassNameParser.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Verifier.h"
37 #include "llvm/IRReader/IRReader.h"
38 #include "llvm/Pass.h"
39 #include "llvm/PassRegistry.h"
40 #include "llvm/Support/MemoryBuffer.h"
41 #include "llvm/Support/SourceMgr.h"
42 #include "llvm/Support/TargetRegistry.h"
43 #include "llvm/Support/TargetSelect.h"
44 #include "llvm/Target/TargetMachine.h"
45 #include "llvm/Transforms/IPO.h"
46 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
47 #include "llvm/Transforms/Vectorize.h"
48
49 using namespace llvm;
50
51 static codegen::RegisterCodeGenFlags CGF;
52
53 // Define a type for the functions that are compiled and executed
54 typedef void (*LLVMFunc)(int*, int*, int*, int);
55
56 // Helper function to parse command line args and find the optimization level
getOptLevel(const std::vector<const char * > & ExtraArgs,CodeGenOpt::Level & OLvl)57 static void getOptLevel(const std::vector<const char *> &ExtraArgs,
58 CodeGenOpt::Level &OLvl) {
59 // Find the optimization level from the command line args
60 OLvl = CodeGenOpt::Default;
61 for (auto &A : ExtraArgs) {
62 if (A[0] == '-' && A[1] == 'O') {
63 switch(A[2]) {
64 case '0': OLvl = CodeGenOpt::None; break;
65 case '1': OLvl = CodeGenOpt::Less; break;
66 case '2': OLvl = CodeGenOpt::Default; break;
67 case '3': OLvl = CodeGenOpt::Aggressive; break;
68 default:
69 errs() << "error: opt level must be between 0 and 3.\n";
70 std::exit(1);
71 }
72 }
73 }
74 }
75
ErrorAndExit(std::string message)76 static void ErrorAndExit(std::string message) {
77 errs()<< "ERROR: " << message << "\n";
78 std::exit(1);
79 }
80
81 // Helper function to add optimization passes to the TargetMachine at the
82 // specified optimization level, OptLevel
AddOptimizationPasses(legacy::PassManagerBase & MPM,CodeGenOpt::Level OptLevel,unsigned SizeLevel)83 static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
84 CodeGenOpt::Level OptLevel,
85 unsigned SizeLevel) {
86 // Create and initialize a PassManagerBuilder
87 PassManagerBuilder Builder;
88 Builder.OptLevel = OptLevel;
89 Builder.SizeLevel = SizeLevel;
90 Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);
91 Builder.LoopVectorize = true;
92 Builder.populateModulePassManager(MPM);
93 }
94
95 // Mimics the opt tool to run an optimization pass over the provided IR
OptLLVM(const std::string & IR,CodeGenOpt::Level OLvl)96 static std::string OptLLVM(const std::string &IR, CodeGenOpt::Level OLvl) {
97 // Create a module that will run the optimization passes
98 SMDiagnostic Err;
99 LLVMContext Context;
100 std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);
101 if (!M || verifyModule(*M, &errs()))
102 ErrorAndExit("Could not parse IR");
103
104 Triple ModuleTriple(M->getTargetTriple());
105 const TargetOptions Options =
106 codegen::InitTargetOptionsFromCodeGenFlags(ModuleTriple);
107 std::string E;
108 const Target *TheTarget =
109 TargetRegistry::lookupTarget(codegen::getMArch(), ModuleTriple, E);
110 TargetMachine *Machine = TheTarget->createTargetMachine(
111 M->getTargetTriple(), codegen::getCPUStr(), codegen::getFeaturesStr(),
112 Options, codegen::getExplicitRelocModel(),
113 codegen::getExplicitCodeModel(), OLvl);
114 std::unique_ptr<TargetMachine> TM(Machine);
115 codegen::setFunctionAttributes(codegen::getCPUStr(),
116 codegen::getFeaturesStr(), *M);
117
118 legacy::PassManager Passes;
119
120 Passes.add(new TargetLibraryInfoWrapperPass(ModuleTriple));
121 Passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
122
123 LLVMTargetMachine <M = static_cast<LLVMTargetMachine &>(*TM);
124 Passes.add(LTM.createPassConfig(Passes));
125
126 Passes.add(createVerifierPass());
127
128 AddOptimizationPasses(Passes, OLvl, 0);
129
130 // Add a pass that writes the optimized IR to an output stream
131 std::string outString;
132 raw_string_ostream OS(outString);
133 Passes.add(createPrintModulePass(OS, "", false));
134
135 Passes.run(*M);
136
137 return OS.str();
138 }
139
140 // Takes a function and runs it on a set of inputs
141 // First determines whether f is the optimized or unoptimized function
RunFuncOnInputs(LLVMFunc f,int Arr[kNumArrays][kArraySize])142 static void RunFuncOnInputs(LLVMFunc f, int Arr[kNumArrays][kArraySize]) {
143 for (int i = 0; i < kNumArrays / 3; i++)
144 f(Arr[i], Arr[i + (kNumArrays / 3)], Arr[i + (2 * kNumArrays / 3)],
145 kArraySize);
146 }
147
148 // Takes a string of IR and compiles it using LLVM's JIT Engine
CreateAndRunJITFunc(const std::string & IR,CodeGenOpt::Level OLvl)149 static void CreateAndRunJITFunc(const std::string &IR, CodeGenOpt::Level OLvl) {
150 SMDiagnostic Err;
151 LLVMContext Context;
152 std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);
153 if (!M)
154 ErrorAndExit("Could not parse IR");
155
156 Function *EntryFunc = M->getFunction("foo");
157 if (!EntryFunc)
158 ErrorAndExit("Function not found in module");
159
160 std::string ErrorMsg;
161 Triple ModuleTriple(M->getTargetTriple());
162
163 EngineBuilder builder(std::move(M));
164 builder.setMArch(codegen::getMArch());
165 builder.setMCPU(codegen::getCPUStr());
166 builder.setMAttrs(codegen::getFeatureList());
167 builder.setErrorStr(&ErrorMsg);
168 builder.setEngineKind(EngineKind::JIT);
169 builder.setMCJITMemoryManager(std::make_unique<SectionMemoryManager>());
170 builder.setOptLevel(OLvl);
171 builder.setTargetOptions(
172 codegen::InitTargetOptionsFromCodeGenFlags(ModuleTriple));
173
174 std::unique_ptr<ExecutionEngine> EE(builder.create());
175 if (!EE)
176 ErrorAndExit("Could not create execution engine");
177
178 EE->finalizeObject();
179 EE->runStaticConstructorsDestructors(false);
180
181 #if defined(__GNUC__) && !defined(__clang) && \
182 ((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
183 // Silence
184 //
185 // warning: ISO C++ forbids casting between pointer-to-function and
186 // pointer-to-object [-Wpedantic]
187 //
188 // Since C++11 this casting is conditionally supported and GCC versions
189 // starting from 4.9.0 don't warn about the cast.
190 #pragma GCC diagnostic push
191 #pragma GCC diagnostic ignored "-Wpedantic"
192 #endif
193 LLVMFunc f = reinterpret_cast<LLVMFunc>(EE->getPointerToFunction(EntryFunc));
194 #if defined(__GNUC__) && !defined(__clang) && \
195 ((__GNUC__ == 4) && (__GNUC_MINOR__ < 9))
196 #pragma GCC diagnostic pop
197 #endif
198
199 // Figure out if we are running the optimized func or the unoptimized func
200 RunFuncOnInputs(f, (OLvl == CodeGenOpt::None) ? UnoptArrays : OptArrays);
201
202 EE->runStaticConstructorsDestructors(true);
203 }
204
205 // Main fuzz target called by ExampleClangLLVMProtoFuzzer.cpp
206 // Mimics the lli tool to JIT the LLVM IR code and execute it
HandleLLVM(const std::string & IR,const std::vector<const char * > & ExtraArgs)207 void clang_fuzzer::HandleLLVM(const std::string &IR,
208 const std::vector<const char *> &ExtraArgs) {
209 // Populate OptArrays and UnoptArrays with the arrays from InputArrays
210 memcpy(OptArrays, InputArrays, kTotalSize);
211 memcpy(UnoptArrays, InputArrays, kTotalSize);
212
213 // Parse ExtraArgs to set the optimization level
214 CodeGenOpt::Level OLvl;
215 getOptLevel(ExtraArgs, OLvl);
216
217 // First we optimize the IR by running a loop vectorizer pass
218 std::string OptIR = OptLLVM(IR, OLvl);
219
220 CreateAndRunJITFunc(OptIR, OLvl);
221 CreateAndRunJITFunc(IR, CodeGenOpt::None);
222
223 if (memcmp(OptArrays, UnoptArrays, kTotalSize))
224 ErrorAndExit("!!!BUG!!!");
225
226 return;
227 }
228