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