06 October 2019

本文学习参考自:plan9 assembly 完全解析Go汇编语言

寄存器

Go 汇编的4个伪寄存器,手写Go 汇编的时候使用:

  • FP:用于引用参数和返回值
  • PC:程序计数器
  • SB:用于引用全局符号
  • SP:指向当前栈帧的BP,引用局部变量

栈结构

函数的定义:TEXT symbol(SB), [flags,] $framesize[-argsize]

                                       caller
                                 +------------------+
                                 |                  |
       +---------------------->  --------------------
       |                         |                  |
       |                         | caller parent BP |
       |           BP(pseudo SP) --------------------
       |                         |                  |
       |                         |   Local Var0     |
       |                         --------------------
       |                         |                  |
       |                         |   .......        |
       |                         --------------------
       |                         |                  |
       |                         |   Local VarN     |
                                 --------------------
 caller stack frame              |                  |
                                 |   callee arg2    |
       |                         |------------------|
       |                         |                  |
       |                         |   callee arg1    |
       |                         |------------------|
       |                         |                  |
       |                         |   callee arg0    |
       |                         ----------------------------------------------+   FP(virtual register)
       |                         |                  |                          |
       |                         |   return addr    |  parent return address   |
       +---------------------->  +------------------+---------------------------    <-------------------------------+
                                                    |  caller BP               |                                    |
                                                    |  (caller frame pointer)  |                                    |
                                     BP(pseudo SP)  ----------------------------                                    |
                                                    |                          |                                    |
                                                    |     Local Var0           |                                    |
                                                    ----------------------------                                    |
                                                    |                          |
                                                    |     Local Var1           |
                                                    ----------------------------                            callee stack frame
                                                    |                          |
                                                    |       .....              |
                                                    ----------------------------                                    |
                                                    |                          |                                    |
                                                    |     Local VarN           |                                    |
                                  SP(Real Register) ----------------------------                                    |
                                                    |                          |                                    |
                                                    |                          |                                    |
                                                    |                          |                                    |
                                                    |                          |                                    |
                                                    |                          |                                    |
                                                    +--------------------------+    <-------------------------------+

                                                              callee
  • return addr是执行CALL指令时,将过程调用返回地址入栈的,同时物理寄存器SP+8字节
  • 当过程调用的frame size > 0时,caller BP才会入栈
  • 通过go tool compile -S foo.gogo tool objdump bin显示的汇编里没有伪寄存器