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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 //
     25 //===--------------------------------------------------------------------===//
     26 
     27 #include "BrainF.h"
     28 #include "llvm/Analysis/Verifier.h"
     29 #include "llvm/Bitcode/ReaderWriter.h"
     30 #include "llvm/ExecutionEngine/GenericValue.h"
     31 #include "llvm/ExecutionEngine/JIT.h"
     32 #include "llvm/IR/Constants.h"
     33 #include "llvm/Support/CommandLine.h"
     34 #include "llvm/Support/ManagedStatic.h"
     35 #include "llvm/Support/TargetSelect.h"
     36 #include "llvm/Support/raw_ostream.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::getInt32Ty(mod->getContext()),
     61                         IntegerType::getInt32Ty(mod->getContext()),
     62                         PointerType::getUnqual(PointerType::getUnqual(
     63                           IntegerType::getInt8Ty(mod->getContext()))), NULL));
     64   {
     65     Function::arg_iterator args = main_func->arg_begin();
     66     Value *arg_0 = args++;
     67     arg_0->setName("argc");
     68     Value *arg_1 = args++;
     69     arg_1->setName("argv");
     70   }
     71 
     72   //main.0:
     73   BasicBlock *bb = BasicBlock::Create(mod->getContext(), "main.0", main_func);
     74 
     75   //call void @brainf()
     76   {
     77     CallInst *brainf_call = CallInst::Create(mod->getFunction("brainf"),
     78                                              "", bb);
     79     brainf_call->setTailCall(false);
     80   }
     81 
     82   //ret i32 0
     83   ReturnInst::Create(mod->getContext(),
     84                      ConstantInt::get(mod->getContext(), APInt(32, 0)), bb);
     85 }
     86 
     87 int main(int argc, char **argv) {
     88   cl::ParseCommandLineOptions(argc, argv, " BrainF compiler\n");
     89 
     90   LLVMContext &Context = getGlobalContext();
     91 
     92   if (InputFilename == "") {
     93     errs() << "Error: You must specify the filename of the program to "
     94     "be compiled.  Use --help to see the options.\n";
     95     abort();
     96   }
     97 
     98   //Get the output stream
     99   raw_ostream *out = &outs();
    100   if (!JIT) {
    101     if (OutputFilename == "") {
    102       std::string base = InputFilename;
    103       if (InputFilename == "-") { base = "a"; }
    104 
    105       // Use default filename.
    106       OutputFilename = base+".bc";
    107     }
    108     if (OutputFilename != "-") {
    109       std::string ErrInfo;
    110       out = new raw_fd_ostream(OutputFilename.c_str(), ErrInfo,
    111                                sys::fs::F_Binary);
    112     }
    113   }
    114 
    115   //Get the input stream
    116   std::istream *in = &std::cin;
    117   if (InputFilename != "-")
    118     in = new std::ifstream(InputFilename.c_str());
    119 
    120   //Gather the compile flags
    121   BrainF::CompileFlags cf = BrainF::flag_off;
    122   if (ArrayBoundsChecking)
    123     cf = BrainF::CompileFlags(cf | BrainF::flag_arraybounds);
    124 
    125   //Read the BrainF program
    126   BrainF bf;
    127   Module *mod = bf.parse(in, 65536, cf, Context); //64 KiB
    128   if (in != &std::cin)
    129     delete in;
    130   addMainFunction(mod);
    131 
    132   //Verify generated code
    133   if (verifyModule(*mod)) {
    134     errs() << "Error: module failed verification.  This shouldn't happen.\n";
    135     abort();
    136   }
    137 
    138   //Write it out
    139   if (JIT) {
    140     InitializeNativeTarget();
    141 
    142     outs() << "------- Running JIT -------\n";
    143     ExecutionEngine *ee = EngineBuilder(mod).create();
    144     std::vector<GenericValue> args;
    145     Function *brainf_func = mod->getFunction("brainf");
    146     GenericValue gv = ee->runFunction(brainf_func, args);
    147   } else {
    148     WriteBitcodeToFile(mod, *out);
    149   }
    150 
    151   //Clean up
    152   if (out != &outs())
    153     delete out;
    154   delete mod;
    155 
    156   llvm_shutdown();
    157 
    158   return 0;
    159 }
    160