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      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/Support/CommandLine.h"
     35 #include "llvm/Support/ManagedStatic.h"
     36 #include "llvm/Support/TargetSelect.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 }
    161