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/Support/CommandLine.h"
36 #include "llvm/Support/ManagedStatic.h"
37 #include <fstream>
38 #include <iostream>
39 using namespace llvm;
40 
41 //Command line options
42 
43 static cl::opt<std::string>
44 InputFilename(cl::Positional, cl::desc("<input brainf>"));
45 
46 static cl::opt<std::string>
47 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
48 
49 static cl::opt<bool>
50 ArrayBoundsChecking("abc", cl::desc("Enable array bounds checking"));
51 
52 static cl::opt<bool>
53 JIT("jit", cl::desc("Run program Just-In-Time"));
54 
55 
56 //Add main function so can be fully compiled
57 void addMainFunction(Module *mod) {
58   //define i32 @main(i32 %argc, i8 **%argv)
59   Function *main_func = cast<Function>(mod->
60     getOrInsertFunction("main", IntegerType::Int32Ty, IntegerType::Int32Ty,
61                         PointerType::getUnqual(PointerType::getUnqual(
62                           IntegerType::Int8Ty)), NULL));
63   {
64     Function::arg_iterator args = main_func->arg_begin();
65     Value *arg_0 = args++;
66     arg_0->setName("argc");
67     Value *arg_1 = args++;
68     arg_1->setName("argv");
69   }
70 
71   //main.0:
72   BasicBlock *bb = BasicBlock::Create("main.0", main_func);
73 
74   //call void @brainf()
75   {
76     CallInst *brainf_call = CallInst::Create(mod->getFunction("brainf"),
77                                              "", bb);
78     brainf_call->setTailCall(false);
79   }
80 
81   //ret i32 0
82   ReturnInst::Create(ConstantInt::get(APInt(32, 0)), bb);
83 }
84 
85 int main(int argc, char **argv) {
86   cl::ParseCommandLineOptions(argc, argv, " BrainF compiler\n");
87 
88   if (InputFilename == "") {
89     std::cerr<<"Error: You must specify the filename of the program to "
90     "be compiled.  Use --help to see the options.\n";
91     abort();
92   }
93 
94   //Get the output stream
95   std::ostream *out = &std::cout;
96   if (!JIT) {
97     if (OutputFilename == "") {
98       std::string base = InputFilename;
99       if (InputFilename == "-") {base = "a";}
100 
101       //Use default filename
102       const char *suffix = ".bc";
103       OutputFilename = base+suffix;
104     }
105     if (OutputFilename != "-") {
106       out = new std::
107         ofstream(OutputFilename.c_str(),
108                  std::ios::out | std::ios::trunc | std::ios::binary);
109     }
110   }
111 
112   //Get the input stream
113   std::istream *in = &std::cin;
114   if (InputFilename != "-") {
115     in = new std::ifstream(InputFilename.c_str());
116   }
117 
118   //Gather the compile flags
119   BrainF::CompileFlags cf = BrainF::flag_off;
120   if (ArrayBoundsChecking) {
121     cf = BrainF::CompileFlags(cf | BrainF::flag_arraybounds);
122   }
123 
124   //Read the BrainF program
125   BrainF bf;
126   Module *mod = bf.parse(in, 65536, cf); //64 KiB
127   if (in != &std::cin) {delete in;}
128   addMainFunction(mod);
129 
130   //Verify generated code
131   if (verifyModule(*mod)) {
132     std::cerr<<"Error: module failed verification.  This shouldn't happen.\n";
133     abort();
134   }
135 
136   //Write it out
137   if (JIT) {
138     std::cout << "------- Running JIT -------\n";
139     ExistingModuleProvider *mp = new ExistingModuleProvider(mod);
140     ExecutionEngine *ee = ExecutionEngine::create(mp, false);
141     std::vector<GenericValue> args;
142     Function *brainf_func = mod->getFunction("brainf");
143     GenericValue gv = ee->runFunction(brainf_func, args);
144   } else {
145     WriteBitcodeToFile(mod, *out);
146   }
147 
148   //Clean up
149   if (out != &std::cout) {delete out;}
150   delete mod;
151 
152   llvm_shutdown();
153 
154   return 0;
155 }
156