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
56 using namespace llvm;
57
58 //Command line options
59
60 static cl::opt<std::string>
61 InputFilename(cl::Positional, cl::desc("<input brainf>"));
62
63 static cl::opt<std::string>
64 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
65
66 static cl::opt<bool>
67 ArrayBoundsChecking("abc", cl::desc("Enable array bounds checking"));
68
69 static cl::opt<bool>
70 JIT("jit", cl::desc("Run program Just-In-Time"));
71
72 //Add main function so can be fully compiled
addMainFunction(Module * mod)73 void 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
main(int argc,char ** argv)106 int 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