1 //===-- BrainFDriver.cpp - BrainF compiler driver -----------------------===//
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 program converts the BrainF language into LLVM assembly,
11 // which it can then run using the JIT or output as BitCode.
12 //
13 // This implementation has a tape of 65536 bytes,
14 // with the head starting in the middle.
15 // Range checking is off by default, so be careful.
16 // It can be enabled with -abc.
17 //
18 // Use:
19 // ./BrainF -jit      prog.bf          #Run program now
20 // ./BrainF -jit -abc prog.bf          #Run program now safely
21 // ./BrainF           prog.bf          #Write as BitCode
22 //
23 // lli prog.bf.bc                      #Run generated BitCode
24 // llvm-ld -native -o=prog prog.bf.bc  #Compile BitCode into native executable
25 //
26 //===--------------------------------------------------------------------===//
27 
28 #include "BrainF.h"
29 #include "llvm/Constants.h"
30 #include "llvm/ModuleProvider.h"
31 #include "llvm/Analysis/Verifier.h"
32 #include "llvm/Bitcode/ReaderWriter.h"
33 #include "llvm/ExecutionEngine/GenericValue.h"
34 #include "llvm/ExecutionEngine/JIT.h"
35 #include "llvm/Target/TargetSelect.h"
36 #include "llvm/Support/CommandLine.h"
37 #include "llvm/Support/ManagedStatic.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include <iostream>
40 #include <fstream>
41 using namespace llvm;
42 
43 //Command line options
44 
45 static cl::opt<std::string>
46 InputFilename(cl::Positional, cl::desc("<input brainf>"));
47 
48 static cl::opt<std::string>
49 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
50 
51 static cl::opt<bool>
52 ArrayBoundsChecking("abc", cl::desc("Enable array bounds checking"));
53 
54 static cl::opt<bool>
55 JIT("jit", cl::desc("Run program Just-In-Time"));
56 
57 
58 //Add main function so can be fully compiled
59 void addMainFunction(Module *mod) {
60   //define i32 @main(i32 %argc, i8 **%argv)
61   Function *main_func = cast<Function>(mod->
62     getOrInsertFunction("main", IntegerType::getInt32Ty(mod->getContext()),
63                         IntegerType::getInt32Ty(mod->getContext()),
64                         PointerType::getUnqual(PointerType::getUnqual(
65                           IntegerType::getInt8Ty(mod->getContext()))), NULL));
66   {
67     Function::arg_iterator args = main_func->arg_begin();
68     Value *arg_0 = args++;
69     arg_0->setName("argc");
70     Value *arg_1 = args++;
71     arg_1->setName("argv");
72   }
73 
74   //main.0:
75   BasicBlock *bb = BasicBlock::Create(mod->getContext(), "main.0", main_func);
76 
77   //call void @brainf()
78   {
79     CallInst *brainf_call = CallInst::Create(mod->getFunction("brainf"),
80                                              "", bb);
81     brainf_call->setTailCall(false);
82   }
83 
84   //ret i32 0
85   ReturnInst::Create(mod->getContext(),
86                      ConstantInt::get(mod->getContext(), APInt(32, 0)), bb);
87 }
88 
89 int main(int argc, char **argv) {
90   cl::ParseCommandLineOptions(argc, argv, " BrainF compiler\n");
91 
92   LLVMContext &Context = getGlobalContext();
93 
94   if (InputFilename == "") {
95     errs() << "Error: You must specify the filename of the program to "
96     "be compiled.  Use --help to see the options.\n";
97     abort();
98   }
99 
100   //Get the output stream
101   raw_ostream *out = &outs();
102   if (!JIT) {
103     if (OutputFilename == "") {
104       std::string base = InputFilename;
105       if (InputFilename == "-") { base = "a"; }
106 
107       // Use default filename.
108       OutputFilename = base+".bc";
109     }
110     if (OutputFilename != "-") {
111       std::string ErrInfo;
112       out = new raw_fd_ostream(OutputFilename.c_str(), ErrInfo,
113                                raw_fd_ostream::F_Binary);
114     }
115   }
116 
117   //Get the input stream
118   std::istream *in = &std::cin;
119   if (InputFilename != "-")
120     in = new std::ifstream(InputFilename.c_str());
121 
122   //Gather the compile flags
123   BrainF::CompileFlags cf = BrainF::flag_off;
124   if (ArrayBoundsChecking)
125     cf = BrainF::CompileFlags(cf | BrainF::flag_arraybounds);
126 
127   //Read the BrainF program
128   BrainF bf;
129   Module *mod = bf.parse(in, 65536, cf, Context); //64 KiB
130   if (in != &std::cin)
131     delete in;
132   addMainFunction(mod);
133 
134   //Verify generated code
135   if (verifyModule(*mod)) {
136     errs() << "Error: module failed verification.  This shouldn't happen.\n";
137     abort();
138   }
139 
140   //Write it out
141   if (JIT) {
142     InitializeNativeTarget();
143 
144     outs() << "------- Running JIT -------\n";
145     ExecutionEngine *ee = EngineBuilder(mod).create();
146     std::vector<GenericValue> args;
147     Function *brainf_func = mod->getFunction("brainf");
148     GenericValue gv = ee->runFunction(brainf_func, args);
149   } else {
150     WriteBitcodeToFile(mod, *out);
151   }
152 
153   //Clean up
154   if (out != &outs())
155     delete out;
156   delete mod;
157 
158   llvm_shutdown();
159 
160   return 0;
161 }
162