1 //===- llvm-reduce.cpp - The LLVM Delta Reduction utility -----------------===//
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 program tries to reduce an IR test case for a given interesting-ness
10 // test. It runs multiple delta debugging passes in order to minimize the input
11 // file. It's worth noting that this is a part of the bugpoint redesign
12 // proposal, and thus a *temporary* tool that will eventually be integrated
13 // into the bugpoint tool itself.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "DeltaManager.h"
18 #include "ReducerWorkItem.h"
19 #include "TestRunner.h"
20 #include "llvm/Analysis/ProfileSummaryInfo.h"
21 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/Bitcode/BitcodeReader.h"
24 #include "llvm/Bitcode/BitcodeWriter.h"
25 #include "llvm/CodeGen/CommandFlags.h"
26 #include "llvm/CodeGen/MachineFunction.h"
27 #include "llvm/CodeGen/MachineModuleInfo.h"
28 #include "llvm/IR/LegacyPassManager.h"
29 #include "llvm/IR/LLVMContext.h"
30 #include "llvm/IR/Verifier.h"
31 #include "llvm/IRReader/IRReader.h"
32 #include "llvm/MC/TargetRegistry.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/Host.h"
35 #include "llvm/Support/InitLLVM.h"
36 #include "llvm/Support/SourceMgr.h"
37 #include "llvm/Support/TargetSelect.h"
38 #include "llvm/Support/WithColor.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Transforms/IPO.h"
41 #include <system_error>
42 #include <vector>
43 
44 using namespace llvm;
45 
46 cl::OptionCategory LLVMReduceOptions("llvm-reduce options");
47 
48 static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden,
49                           cl::cat(LLVMReduceOptions));
50 static cl::opt<bool> Version("v", cl::desc("Alias for -version"), cl::Hidden,
51                              cl::cat(LLVMReduceOptions));
52 
53 static cl::opt<bool>
54     PrintDeltaPasses("print-delta-passes",
55                      cl::desc("Print list of delta passes, passable to "
56                               "--delta-passes as a comma separated list"),
57                      cl::cat(LLVMReduceOptions));
58 
59 static cl::opt<std::string> InputFilename(cl::Positional, cl::Required,
60                                           cl::desc("<input llvm ll/bc file>"),
61                                           cl::cat(LLVMReduceOptions));
62 
63 static cl::opt<std::string>
64     TestFilename("test", cl::Required,
65                  cl::desc("Name of the interesting-ness test to be run"),
66                  cl::cat(LLVMReduceOptions));
67 
68 static cl::list<std::string>
69     TestArguments("test-arg",
70                   cl::desc("Arguments passed onto the interesting-ness test"),
71                   cl::cat(LLVMReduceOptions));
72 
73 static cl::opt<std::string> OutputFilename(
74     "output", cl::desc("Specify the output file. default: reduced.ll|mir"));
75 static cl::alias OutputFileAlias("o", cl::desc("Alias for -output"),
76                                  cl::aliasopt(OutputFilename),
77                                  cl::cat(LLVMReduceOptions));
78 
79 static cl::opt<bool>
80     ReplaceInput("in-place",
81                  cl::desc("WARNING: This option will replace your input file "
82                           "with the reduced version!"),
83                  cl::cat(LLVMReduceOptions));
84 
85 enum class InputLanguages { None, IR, MIR };
86 
87 static cl::opt<InputLanguages>
88     InputLanguage("x", cl::ValueOptional,
89                   cl::desc("Input language ('ir' or 'mir')"),
90                   cl::init(InputLanguages::None),
91                   cl::values(clEnumValN(InputLanguages::IR, "ir", ""),
92                              clEnumValN(InputLanguages::MIR, "mir", "")),
93                   cl::cat(LLVMReduceOptions));
94 
95 static cl::opt<int>
96     MaxPassIterations("max-pass-iterations",
97                       cl::desc("Maximum number of times to run the full set "
98                                "of delta passes (default=5)"),
99                       cl::init(5), cl::cat(LLVMReduceOptions));
100 
101 static codegen::RegisterCodeGenFlags CGF;
102 
103 void writeOutput(ReducerWorkItem &M, StringRef Message) {
104   if (ReplaceInput) // In-place
105     OutputFilename = InputFilename.c_str();
106   else if (OutputFilename.empty() || OutputFilename == "-")
107     OutputFilename = M.isMIR() ? "reduced.mir" : "reduced.ll";
108   std::error_code EC;
109   raw_fd_ostream Out(OutputFilename, EC);
110   if (EC) {
111     errs() << "Error opening output file: " << EC.message() << "!\n";
112     exit(1);
113   }
114   M.print(Out, /*AnnotationWriter=*/nullptr);
115   errs() << Message << OutputFilename << "\n";
116 }
117 
118 void writeBitcode(ReducerWorkItem &M, llvm::raw_ostream &OutStream) {
119   if (M.LTOInfo && M.LTOInfo->IsThinLTO && M.LTOInfo->EnableSplitLTOUnit) {
120     legacy::PassManager PM;
121     PM.add(llvm::createWriteThinLTOBitcodePass(OutStream));
122     PM.run(*(M.M));
123   } else {
124     std::unique_ptr<ModuleSummaryIndex> Index;
125     if (M.LTOInfo && M.LTOInfo->HasSummary) {
126       ProfileSummaryInfo PSI(M);
127       Index = std::make_unique<ModuleSummaryIndex>(
128           buildModuleSummaryIndex(M, nullptr, &PSI));
129     }
130     WriteBitcodeToFile(M, OutStream, Index.get());
131   }
132 }
133 
134 void readBitcode(ReducerWorkItem &M, MemoryBufferRef Data, LLVMContext &Ctx, const char *ToolName) {
135   Expected<BitcodeFileContents> IF = llvm::getBitcodeFileContents(Data);
136   if (!IF) {
137     WithColor::error(errs(), ToolName) << IF.takeError();
138     exit(1);
139   }
140   BitcodeModule BM = IF->Mods[0];
141   Expected<BitcodeLTOInfo> LI = BM.getLTOInfo();
142   Expected<std::unique_ptr<Module>> MOrErr = BM.parseModule(Ctx);
143   if (!LI || !MOrErr) {
144     WithColor::error(errs(), ToolName) << IF.takeError();
145     exit(1);
146   }
147   M.LTOInfo = std::make_unique<BitcodeLTOInfo>(*LI);
148   M.M = std::move(MOrErr.get());
149 }
150 
151 int main(int Argc, char **Argv) {
152   InitLLVM X(Argc, Argv);
153 
154   cl::HideUnrelatedOptions({&LLVMReduceOptions, &getColorCategory()});
155   cl::ParseCommandLineOptions(Argc, Argv, "LLVM automatic testcase reducer.\n");
156 
157   bool ReduceModeMIR = false;
158   if (InputLanguage != InputLanguages::None) {
159     if (InputLanguage == InputLanguages::MIR)
160       ReduceModeMIR = true;
161   } else if (StringRef(InputFilename).endswith(".mir")) {
162     ReduceModeMIR = true;
163   }
164 
165   if (PrintDeltaPasses) {
166     printDeltaPasses(errs());
167     return 0;
168   }
169 
170   LLVMContext Context;
171   std::unique_ptr<TargetMachine> TM;
172 
173   std::unique_ptr<ReducerWorkItem> OriginalProgram =
174       parseReducerWorkItem(Argv[0], InputFilename, Context, TM, ReduceModeMIR);
175   if (!OriginalProgram) {
176     return 1;
177   }
178 
179   // Initialize test environment
180   TestRunner Tester(TestFilename, TestArguments, std::move(OriginalProgram),
181                     std::move(TM), Argv[0]);
182 
183   // Try to reduce code
184   runDeltaPasses(Tester, MaxPassIterations);
185 
186   // Print reduced file to STDOUT
187   if (OutputFilename == "-")
188     Tester.getProgram().print(outs(), nullptr);
189   else
190     writeOutput(Tester.getProgram(), "\nDone reducing! Reduced testcase: ");
191 
192   return 0;
193 }
194