examples/BrainF/BrainF.h

   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
  22 using 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.
  28 class 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