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/Target/TargetSelect.h"
  36 #include "llvm/Support/CommandLine.h"
  37 #include "llvm/Support/ManagedStatic.h"
  38 #include "llvm/Support/raw_ostream.h"
  39 #include <iostream>
  40 #include <fstream>
  41 using namespace llvm;
  42
  43 //Command line options
  44
  45 static cl::opt<std::string>
  46 InputFilename(cl::Positional, cl::desc("<input brainf>"));
  47
  48 static cl::opt<std::string>
  49 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
  50
  51 static cl::opt<bool>
  52 ArrayBoundsChecking("abc", cl::desc("Enable array bounds checking"));
  53
  54 static cl::opt<bool>
  55 JIT("jit", cl::desc("Run program Just-In-Time"));
  56
  57
  58 //Add main function so can be fully compiled
  59 void addMainFunction(Module *mod) {
  60   //define i32 @main(i32 %argc, i8 **%argv)
  61   Function *main_func = cast<Function>(mod->
  62     getOrInsertFunction("main", IntegerType::getInt32Ty(mod->getContext()),
  63                         IntegerType::getInt32Ty(mod->getContext()),
  64                         PointerType::getUnqual(PointerType::getUnqual(
  65                           IntegerType::getInt8Ty(mod->getContext()))), NULL));
  66   {
  67     Function::arg_iterator args = main_func->arg_begin();
  68     Value *arg_0 = args++;
  69     arg_0->setName("argc");
  70     Value *arg_1 = args++;
  71     arg_1->setName("argv");
  72   }
  73
  74   //main.0:
  75   BasicBlock *bb = BasicBlock::Create(mod->getContext(), "main.0", main_func);
  76
  77   //call void @brainf()
  78   {
  79     CallInst *brainf_call = CallInst::Create(mod->getFunction("brainf"),
  80                                              "", bb);
  81     brainf_call->setTailCall(false);
  82   }
  83
  84   //ret i32 0
  85   ReturnInst::Create(mod->getContext(),
  86                      ConstantInt::get(mod->getContext(), APInt(32, 0)), bb);
  87 }
  88
  89 int main(int argc, char **argv) {
  90   cl::ParseCommandLineOptions(argc, argv, " BrainF compiler\n");
  91
  92   LLVMContext &Context = getGlobalContext();
  93
  94   if (InputFilename == "") {
  95     errs() << "Error: You must specify the filename of the program to "
  96     "be compiled.  Use --help to see the options.\n";
  97     abort();
  98   }
  99
 100   //Get the output stream
 101   raw_ostream *out = &outs();
 102   if (!JIT) {
 103     if (OutputFilename == "") {
 104       std::string base = InputFilename;
 105       if (InputFilename == "-") { base = "a"; }
 106
 107       // Use default filename.
 108       OutputFilename = base+".bc";
 109     }
 110     if (OutputFilename != "-") {
 111       std::string ErrInfo;
 112       out = new raw_fd_ostream(OutputFilename.c_str(), ErrInfo,
 113                                raw_fd_ostream::F_Binary);
 114     }
 115   }
 116
 117   //Get the input stream
 118   std::istream *in = &std::cin;
 119   if (InputFilename != "-")
 120     in = new std::ifstream(InputFilename.c_str());
 121
 122   //Gather the compile flags
 123   BrainF::CompileFlags cf = BrainF::flag_off;
 124   if (ArrayBoundsChecking)
 125     cf = BrainF::CompileFlags(cf | BrainF::flag_arraybounds);
 126
 127   //Read the BrainF program
 128   BrainF bf;
 129   Module *mod = bf.parse(in, 65536, cf, Context); //64 KiB
 130   if (in != &std::cin)
 131     delete in;
 132   addMainFunction(mod);
 133
 134   //Verify generated code
 135   if (verifyModule(*mod)) {
 136     errs() << "Error: module failed verification.  This shouldn't happen.\n";
 137     abort();
 138   }
 139
 140   //Write it out
 141   if (JIT) {
 142     InitializeNativeTarget();
 143
 144     outs() << "------- Running JIT -------\n";
 145     ExecutionEngine *ee = EngineBuilder(mod).create();
 146     std::vector<GenericValue> args;
 147     Function *brainf_func = mod->getFunction("brainf");
 148     GenericValue gv = ee->runFunction(brainf_func, args);
 149   } else {
 150     WriteBitcodeToFile(mod, *out);
 151   }
 152
 153   //Clean up
 154   if (out != &outs())
 155     delete out;
 156   delete mod;
 157
 158   llvm_shutdown();
 159
 160   return 0;
 161 }