mysysy/src/include/Backend.h

#pragma once
/**
 * 后端设计需要注意的点
 *
 * label分配   :
 * 全局变量的label,常量的label,basicblock的label,函数入口label,函数出口label
 * 全局数据处理
 * 常量处理
 * 临时变量的处理(包括函数参数也是临时变量)
 * 函数参数的处理
 * 块参数的处理  (如果SSA问题通过块传参解决则需要处理块参数)
 * 函数栈空间结构的设计
 * 块的遍历问题
 * arm32的过程调用约定
 *
 * 后端测试需要注意的点
 *
 * 如何汇编与链接.
 * qemu以及树莓派如何运行.
 */
#include <algorithm>
#include <set>
#include <string>
#include <vector>
#include "IR.h"

using std::find;
using std::map;
using std::pair;
using std::set;
using std::string;
using std::to_string;
using std::vector;

#define Macro_ERROR_MSG(...)                                                   \
  do {                                                                         \
    fprintf(stderr, "ERROR in line-%d of %s: ", __LINE__, __FILE__);           \
    fprintf(stderr, __VA_ARGS__);                                              \
    fprintf(stderr, "\n");                                                     \
    fflush(stderr);                                                            \
    exit(1);                                                                   \
  } while (0);

#define M_emitInst(STR) (space + STR + eol)
#define M_emitComment(STR) (space + "//" + STR + eol)
#define M_emitLabel(STR) (STR + ":" + eol)

// #define REG_EXP

static const string space = string(4, ' ');
static const string eol = "\n";
// only for armv7
static const int int_align = 4;
static const int int_size = 4;
static const int int_p2align = 2;
static const int reg_size = 4;

// default arm32 max imm
//
static const uint32_t maxMovImm = 0xFFF;
static const string stackIndexReg = "fp";

static uint16_t getWordHigh(uint32_t cval) { return (cval >> 16) & 0xFFFF; }
static uint16_t getWordLow(uint32_t cval) { return cval & 0xFFFF; }
//
static string emitInst_1srcR_noDstR(string name, string srcReg) {
  return space + name + " " + srcReg + eol;
}
static string emitInst_2srcR_1dstR(string name, string srcReg0, string srcReg1,
                                   string dstReg) {
  return space + name + " " + dstReg + ", " + srcReg0 + ", " + srcReg1 + eol;
}

namespace sysy {
//
class RegManager {
public:
  //{0,1,2,3,4,5,6,7,8,9,10};
  enum RegId : unsigned {
    R0 = 0,
    R1 = 1,
    R2 = 2,
    R3 = 3,
    R4 = 4,
    R5 = 5,
    R6 = 6,
    R7 = 7,
    R8 = 8,
    R9 = 9,
    R10 = 10,
    RNONE = 1024,
    RANY = 2048,
  };
  static string toString(RegId reg) {
    if (reg == RNONE)
      return "RNONE";
    if (reg == RANY)
      return "RANY";
    return "r" + to_string(reg);
  }
};

class Operand {
public:
  using RegId = RegManager::RegId;
  enum Kind {
    kReg,
    kImm,
  };
  Kind kind;
  union {
    uint32_t imm;
    RegId regId;
  };
  Operand(){};
  Operand(uint32_t imm) : kind(kImm), imm(imm) {}
  Operand(RegId regId) : kind(kReg), regId(regId) {}
  bool isImm(void) { return kind == kImm; }
  bool isReg(void) { return kind == kReg; }
  uint32_t getImm(void) {
    assert(kind == kImm);
    return imm;
  }
  RegId getRegId(void) {
    assert(kind == kReg);
    return regId;
  }
  string toString(void) {
    if (kind == kImm)
      return "#" + to_string(imm);
    else
      return RegManager::toString(regId);
  }
};

class CodeGen {
public:
  using RegId = RegManager::RegId;

private:
  sysy::Module *module;
  Function *curFunc;
  BasicBlock *curBB;
  //
  RegManager regm;
  // globalValue
  bool loadGlobalValByMOVWT = true;
  // basicBlock
  vector<BasicBlock *> linear_bb;
  int bb_no = 0;
  // function params, return value and localVar
  map<Argument *, int> paramsStOffset;
  map<Instruction *, int> localVarStOffset;
  int retValueStOffset = 0;
  size_t stOffsetAcc = 0;
  // label manager
  map<BasicBlock *, string> bb_labels;
  uint64_t label_no = 0;

public:
  CodeGen(Module *module) : module(module) {}
  // code_gen function list
  string code_gen();
  string module_gen(Module *module);
  string function_gen(Function *func);
  string basicBlock_gen(BasicBlock *bb);
  string instruction_gen(Instruction *instr);
  string globaldata_gen();
  string prologueCode_gen(Function *func);
  string epilogueCode_gen(Function *func);
  string literalPoolsCode_gen(Function *func);
  string functionHead_gen(Function *func);
  // Module
  void clearModuleRecord(Module *module) { label_no = 0; }
  // instruction gen function list
  //<dstReg, code>
  pair<RegId, string> loadInst_gen(LoadInst *ldInst, RegId dstRegId);
  string storeInst_gen(StoreInst *stInst);
  pair<RegId, string> allocaInst_gen(AllocaInst *aInst, RegId dstRegId);
  string returnInst_gen(ReturnInst *retInst);
  pair<RegId, string> callInst_gen(CallInst *retInst, RegId dstRegId);
  pair<RegId, string> binaryInst_gen(BinaryInst *bInst, RegId dstRegId);
  pair<RegId, string> unaryInst_gen(UnaryInst *bInst, RegId dstRegId);
  string uncondBrInst_gen(UncondBrInst *ubInst);
  string condBrInst_gen(CondBrInst *ubInst);

  //
  string storeRegToStack_gen(RegId regId, Instruction *inst) {
    string code;
    /**
     *code in here
     */
    return code;
  }
  // function
  void clearFunctionRecord(Function *func) {
    localVarStOffset.clear();
    paramsStOffset.clear();
    retValueStOffset = 0;
    bb_labels.clear();
    //
    stOffsetAcc = 0;
  }
  string getBBLabel(BasicBlock *bb) {
    auto t = bb_labels.find(bb);
    string label;
    if (t == bb_labels.end()) {
      label = ".LBB_" + to_string(label_no++);
      bb_labels.emplace(bb, label);
    } else {
      label = t->second;
    }
    return label;
  }
};

} // namespace sysy