1//===-- BrainFDriver.cpp - BrainF compiler driver -------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This program converts the BrainF language into LLVM assembly,
10// which it can then run using the JIT or output as BitCode.
11//
12// This implementation has a tape of 65536 bytes,
13// with the head starting in the middle.
14// Range checking is off by default, so be careful.
15// It can be enabled with -abc.
16//
17// Use:
18// ./BrainF -jit      prog.bf          #Run program now
19// ./BrainF -jit -abc prog.bf          #Run program now safely
20// ./BrainF           prog.bf          #Write as BitCode
21//
22// lli prog.bf.bc                      #Run generated BitCode
23//
24//===----------------------------------------------------------------------===//
25
26#include "BrainF.h"
27#include "llvm/ADT/APInt.h"
28#include "llvm/Bitcode/BitcodeWriter.h"
29#include "llvm/ExecutionEngine/ExecutionEngine.h"
30#include "llvm/ExecutionEngine/GenericValue.h"
31#include "llvm/ExecutionEngine/MCJIT.h"
32#include "llvm/IR/BasicBlock.h"
33#include "llvm/IR/Constants.h"
34#include "llvm/IR/DerivedTypes.h"
35#include "llvm/IR/Function.h"
36#include "llvm/IR/Instructions.h"
37#include "llvm/IR/LLVMContext.h"
38#include "llvm/IR/Module.h"
39#include "llvm/IR/Value.h"
40#include "llvm/IR/Verifier.h"
41#include "llvm/Support/Casting.h"
42#include "llvm/Support/CommandLine.h"
43#include "llvm/Support/FileSystem.h"
44#include "llvm/Support/ManagedStatic.h"
45#include "llvm/Support/TargetSelect.h"
46#include "llvm/Support/raw_ostream.h"
47#include <algorithm>
48#include <cstdlib>
49#include <fstream>
50#include <iostream>
51#include <memory>
52#include <string>
53#include <system_error>
54#include <vector>
55
56using namespace llvm;
57
58//Command line options
59
60static cl::opt<std::string>
61InputFilename(cl::Positional, cl::desc("<input brainf>"));
62
63static cl::opt<std::string>
64OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
65
66static cl::opt<bool>
67ArrayBoundsChecking("abc", cl::desc("Enable array bounds checking"));
68
69static cl::opt<bool>
70JIT("jit", cl::desc("Run program Just-In-Time"));
71
72//Add main function so can be fully compiled
73void addMainFunction(Module *mod) {
74  //define i32 @main(i32 %argc, i8 **%argv)
75  FunctionType *main_func_fty = FunctionType::get(
76      Type::getInt32Ty(mod->getContext()),
77      {Type::getInt32Ty(mod->getContext()),
78       Type::getInt8Ty(mod->getContext())->getPointerTo()->getPointerTo()},
79      false);
80  Function *main_func =
81      Function::Create(main_func_fty, Function::ExternalLinkage, "main", mod);
82
83  {
84    Function::arg_iterator args = main_func->arg_begin();
85    Value *arg_0 = &*args++;
86    arg_0->setName("argc");
87    Value *arg_1 = &*args++;
88    arg_1->setName("argv");
89  }
90
91  //main.0:
92  BasicBlock *bb = BasicBlock::Create(mod->getContext(), "main.0", main_func);
93
94  //call void @brainf()
95  {
96    CallInst *brainf_call = CallInst::Create(mod->getFunction("brainf"),
97                                             "", bb);
98    brainf_call->setTailCall(false);
99  }
100
101  //ret i32 0
102  ReturnInst::Create(mod->getContext(),
103                     ConstantInt::get(mod->getContext(), APInt(32, 0)), bb);
104}
105
106int main(int argc, char **argv) {
107  cl::ParseCommandLineOptions(argc, argv, " BrainF compiler\n");
108
109  LLVMContext Context;
110
111  if (InputFilename == "") {
112    errs() << "Error: You must specify the filename of the program to "
113    "be compiled.  Use --help to see the options.\n";
114    abort();
115  }
116
117  //Get the output stream
118  raw_ostream *out = &outs();
119  if (!JIT) {
120    if (OutputFilename == "") {
121      std::string base = InputFilename;
122      if (InputFilename == "-") { base = "a"; }
123
124      // Use default filename.
125      OutputFilename = base+".bc";
126    }
127    if (OutputFilename != "-") {
128      std::error_code EC;
129      out = new raw_fd_ostream(OutputFilename, EC, sys::fs::OF_None);
130    }
131  }
132
133  //Get the input stream
134  std::istream *in = &std::cin;
135  if (InputFilename != "-")
136    in = new std::ifstream(InputFilename.c_str());
137
138  //Gather the compile flags
139  BrainF::CompileFlags cf = BrainF::flag_off;
140  if (ArrayBoundsChecking)
141    cf = BrainF::CompileFlags(cf | BrainF::flag_arraybounds);
142
143  //Read the BrainF program
144  BrainF bf;
145  std::unique_ptr<Module> Mod(bf.parse(in, 65536, cf, Context)); // 64 KiB
146  if (in != &std::cin)
147    delete in;
148  addMainFunction(Mod.get());
149
150  //Verify generated code
151  if (verifyModule(*Mod)) {
152    errs() << "Error: module failed verification.  This shouldn't happen.\n";
153    abort();
154  }
155
156  //Write it out
157  if (JIT) {
158    InitializeNativeTarget();
159    InitializeNativeTargetAsmPrinter();
160
161    outs() << "------- Running JIT -------\n";
162    Module &M = *Mod;
163    ExecutionEngine *ee = EngineBuilder(std::move(Mod)).create();
164    if (!ee) {
165      errs() << "Error: execution engine creation failed.\n";
166      abort();
167    }
168    std::vector<GenericValue> args;
169    Function *brainf_func = M.getFunction("brainf");
170    GenericValue gv = ee->runFunction(brainf_func, args);
171    // Genereated code calls putchar, and output is not guaranteed without fflush.
172    // The better place for fflush(stdout) call would be the generated code, but it
173    // is unmanageable because stdout linkage name depends on stdlib implementation.
174    fflush(stdout);
175  } else {
176    WriteBitcodeToFile(*Mod, *out);
177  }
178
179  //Clean up
180  if (out != &outs())
181    delete out;
182
183  llvm_shutdown();
184
185  return 0;
186}
187