c++ - 创建 Stack VM 时出现段错误

Question

我正在尝试创建一个 VM，它现在可以运行简单的东西。但是，编译后，我尝试运行它但出现了段错误。有 4 个文件:stack-vm.h、stack-vm.cpp、main.cpp、makefile .

堆栈虚拟机.h :

#ifndef STACK_VM_H
  #define STACK_VM_H

  #include <iostream>
  #include <vector>

  //type definitions
  typedef int32_t i32;

  class StackVM {

  private:
    i32 pc = 100; // program counter
    i32 sp = 0; // stack pointer
    std::vector<i32> memory;
    i32 typ = 0;
    i32 dat = 0;
    i32 running = 1;

    i32 getType(i32 instruction);
    i32 getData(i32 instruction);
    void fetch();
    void decode();
    void execute();
    void doPrimitive();

  public:
    StackVM();
    void run();
    void loadProgram(std::vector<i32> prog);

  };

#endif

堆栈-vm.cpp :

    #include "stack-vm.h"

StackVM::StackVM() {
  memory.reserve(1000000);
}

i32 StackVM::getType(i32 instruction) {
  i32 type = 0xc0000000;
  type = (type & instruction) >> 30;
  return type;
}

i32 StackVM::getData(i32 instruction) {
  i32 data = 0x3fffffff;
  data = data & instruction;
  return data;
}
void StackVM::fetch() {
  pc++;
}

void StackVM::decode() {
  typ = getType(memory[pc]);
  dat = getData(memory[pc]);
}

void StackVM::execute() {
  if (typ == 0 || typ == 2) {
    sp++;
    memory[sp] = dat;
  } else {
    doPrimitive();
  }
}

void StackVM::doPrimitive() {
  switch (dat) {
    case 0: // halt
      std::cout << "halt" << std::endl;
      running = 0;
      break;

    case 1: // add
      std::cout << "add " << memory[sp - 1] << " " << memory[sp] << std::endl;
      memory[sp - 1] = memory[sp - 1] + memory[sp];
      break;
  }
}

void StackVM::run() {
  pc -= 1;
  while (running) {
    fetch();
    decode();
    execute();
    std::cout << "tos: " << memory[sp] << std::endl;
  }
}

void StackVM::loadProgram(std::vector<i32> prog) {
  for (i32 i = 0; 1 < prog.size(); i++) {
    memory[pc + i] = prog[i];
  }
}

main.cpp :

    #include "stack-vm.h"

int main(int argc, char* argv[]) {
  StackVM vm;
  std::vector<i32> prog{3, 4, 0x40000001, 0x40000000};
  vm.loadProgram(prog);

  return 0;
}

生成文件:

        CFLAGS=-std=c++11

    all: stack-vm

    stack-vm: stack-vm.o main.o
        $(CXX) $(CFLAGS) stack-vm.o main.o -o stack-vm

    main.o: main.cpp
        $(CXX) $(CFLAGS) -c main.cpp

    stack-vm.o: stack-vm.h stack-vm.cpp
        $(CXX) $(CFLAGS) -c stack-vm.cpp

    clean:
        rm -f *.o stack-vm

感谢您的回答。

Answer 1

行:

for (i32 i = 0; 1 < prog.size(); i++)

不正确，应该是i，不是1。

此外，reserve 设置的是容量，而不是 vector 的大小。你应该使用调整大小。