examples/BrainF/BrainFDriver.cpp

   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 }