# ubuntu
sudo apt update
sudo apt install build-essential flex bison -y

Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:        22.04
Codename:       jammy

gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0
flex 2.6.4
bison (GNU Bison) 3.8.2

├── asm
│   ├── asm.py             # 中间代码转汇编程序
│   ├── const.py           # 一些常量, 寄存器说明
│   ├── dist               # 汇编及可执行文件
│   │   ├── ...
│   └── README.md
├── assets                 # 效果图
│   ├── ...
├── ast                    # 抽象语法树
│   ├── ast.c
│   ├── ast.h
│   ├── graph              # 绘制抽象语法树
│   │   ├── graph.c
│   │   └── graph.h
│   └── README.md
├── compile                # 最终生成中间代码的可执行文件
├── intermediate           # 中间代码生成
│   ├── intermediate.c
│   └── intermediate.h
├── lexer.l                # 词法分析
├── Makefile               # 构建脚本
├── output                 # 中间代码输出
│   ├── ...
├── parser.y               # 语法分析
├── README.md
├── semantics              # 类型检测等
│   ├── semantics.c
│   └── semantics.h
├── symtab                 # 符号表
│   ├── symtab.c
│   └── symtab.h
├── test                   # 测试用例
│   ├── dist               # 可执行文件
│   ├── ...
│   ├── Makefile
│   ├── pointer.c
│   └── README.md
└── utils
    ├── common.c
    ├── common.h            # 公共函数
    └── types.h             # 结点类型

100: (FUNCTION, fib, _, _)
101: (PARAM, var0, _, _)
102: (PARAM, var1, _, _)
103: (=, int(1000), _, temp0)
104: (>, var0, temp0, 106)
105: (GOTO, _, _, 115)
106: (*, var0, var1, temp1)
107: (=, int(5), _, temp2)
108: (%, temp1, temp2, temp3)
109: (=, int(1), _, temp4)
110: (=, int(0), _, temp5)
111: (-, temp5, temp4, temp6)
112: (-, temp3, temp6, temp7)
113: (RETURN, _, _, temp7)
114: (GOTO, _, _, 124)
115: (#, #, #, #)
116: (+, var0, var1, temp8)
117: (ARG, temp8, _, _)
118: (ARG, var0, _, _)
119: (CALL, fib, _, temp9)
120: (=, int(1), _, temp10)
121: (+, temp9, temp10, temp11)
122: (RETURN, _, _, temp11)
123: (GOTO, _, _, 124)
124: (LEAVE, _, _, _)
125: (FUNCTION, main, _, _)
126: (#, #, #, #)
127: (=, string("%d\n"), _, temp12)
128: (ARG, temp12, _, _)
129: (#, #, #, #) ------------------> 这个不是四元式中的, 只不过方便转汇编而多加的
130: (=, int(1), _, temp13)
131: (ARG, temp13, _, _)
132: (=, int(1), _, temp14)
133: (ARG, temp14, _, _)
134: (CALL, fib, _, temp15)
135: (ARG, temp15, _, _)
136: (CALL, printf, _, _)
137: (=, int(0), _, temp16)
138: (RETURN, _, _, temp16)
139: (GOTO, _, _, 140)
140: (LEAVE, _, _, _)

	.file "func.c"
	.text
	.globl fib
	.type fib, @function
fib:
LFB0:
	pushq %rbp
	movq %rsp, %rbp
	subq $16, %rsp
	movl %edi, -4(%rbp)
	movl %esi, -8(%rbp)
	cmpl $1000, -4(%rbp)
	jg .L0
	jmp .L1
.L0:
	movl -4(%rbp), %eax
	imull -8(%rbp), %eax
	cltd
	movl $5, %ecx
	idivl %ecx
	movl $0, %ebx
	subl $1, %ebx
	movl %edx, %eax
	subl %ebx, %eax
	jmp .L2
.L1:
	movl -4(%rbp), %edx
	movl -8(%rbp), %eax
	addl %eax, %edx
	movl -4(%rbp), %esi
	movl %edx, %edi
	CALL fib
	movl %eax, %edx
	movl $1, %eax
	addl %eax, %edx
	movl %edx, %eax
	jmp .L2
.L2:
	leave
	ret
.LC0:
	.string "%d\n"
	.text
	.globl main
	.type main, @function
main:
LFB1:
	pushq %rbp
	movq %rsp, %rbp
	movl $1, %esi
	movl $1, %edi
	CALL fib
	movl %eax, %esi
	leaq .LC0(%rip), %rax
	movq %rax, %rdi
	movl $0, %eax
	CALL printf@PLT
	movl $0, %eax
	jmp .L3
.L3:
	popq %rbp
	ret

assigment : var_ref ASSIGN expression
          { 
            checkAssign($1, $3); // 检查赋值是否合理
            $$ = newAstAssignNode($1, $3); // 变量赋值  
          };

return : RETURN expression SEMI
       {  
            $$ = newAstReturnNode(func->function->type, $2); 
            checkFunctionReturn(func, (AstReturnNode*)$$); /* 检测返回是否符合函数定义 */ 
       }
       | RETURN SEMI
       { 
            $$ = newAstReturnNode(func->function->type, NULL); 
            checkFunctionReturn(func, (AstReturnNode*)$$);
       }
       ;