1//===-- BrainF.h - BrainF compiler class ------------------------*- C++ -*-===//
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 class stores the data for the BrainF compiler so it doesn't have
10// to pass all of it around. The main method is parse.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef BRAINF_H
15#define BRAINF_H
16
17#include "llvm/IR/IRBuilder.h"
18#include "llvm/IR/LLVMContext.h"
19#include "llvm/IR/Module.h"
20#include <istream>
21
22using namespace llvm;
23
24/// This class provides a parser for the BrainF language.
25/// The class itself is made to store values during
26/// parsing so they don't have to be passed around
27/// as much.
28class BrainF {
29 public:
30 /// Options for how BrainF should compile
31 enum CompileFlags {
32 flag_off = 0,
33 flag_arraybounds = 1
34 };
35
36 /// This is the main method. It parses BrainF from in1
37 /// and returns the module with a function
38 /// void brainf()
39 /// containing the resulting code.
40 /// On error, it calls abort.
41 /// The caller must delete the returned module.
42 Module *parse(std::istream *in1, int mem, CompileFlags cf,
43 LLVMContext& C);
44
45 protected:
46 /// The different symbols in the BrainF language
47 enum Symbol {
48 SYM_NONE,
49 SYM_READ,
50 SYM_WRITE,
51 SYM_MOVE,
52 SYM_CHANGE,
53 SYM_LOOP,
54 SYM_ENDLOOP,
55 SYM_EOF
56 };
57
58 /// Names of the different parts of the language.
59 /// Tape is used for reading and writing the tape.
60 /// headreg is used for the position of the head.
61 /// label is used for the labels for the BasicBlocks.
62 /// testreg is used for testing the loop exit condition.
63 static const char *tapereg;
64 static const char *headreg;
65 static const char *label;
66 static const char *testreg;
67
68 /// Put the brainf function preamble and other fixed pieces of code
69 void header(LLVMContext& C);
70
71 /// The main loop for parsing. It calls itself recursively
72 /// to handle the depth of nesting of "[]".
73 void readloop(PHINode *phi, BasicBlock *oldbb,
74 BasicBlock *testbb, LLVMContext &Context);
75
76 /// Constants during parsing
77 int memtotal;
78 CompileFlags comflag;
79 std::istream *in;
80 Module *module;
81 Function *brainf_func;
82 FunctionCallee getchar_func;
83 FunctionCallee putchar_func;
84 Value *ptr_arr;
85 Value *ptr_arrmax;
86 BasicBlock *endbb;
87 BasicBlock *aberrorbb;
88
89 /// Variables
90 IRBuilder<> *builder;
91 Value *curhead;
92};
93
94#endif // BRAINF_H
95

source code of llvm/examples/BrainF/BrainF.h