访问寄存器不使用内联汇编用gcc [英] Accessing a register without using inline assembly with gcc
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问题描述
我想不写行内assembly.The的原因,我想这样做阅读栈指针寄存器的值,因为我想栈指针寄存器的值赋给数组的元素,我觉得它繁琐的访问数组使用内联汇编。所以,我想要做这样的事情。
I want to read the stack pointer register value without writing inline assembly.The reason I want to do this is because I want to assign the stack pointer register value to an element of an array and I find it cumbersome to access an array using inline assembly. So I would want to do something like that.
register "rsp" long rsp_alias; <--- How do I achieve something like that in gcc?
long current_rsp_value[NUM_OF_THREADS];
current_rsp_value[tid] = rsp_alias;
有没有这样的事情可能用gcc?
Is there anything like that possible with gcc?
推荐答案
有一个快捷方式:
register long rsp asm ("rsp");
演示:
#include<stdio.h>
void foo(void)
{
register long rsp asm ("rsp");
printf("RSP: %lx\n", rsp);
}
int main()
{
register long rsp asm ("rsp");
printf("RSP: %lx\n", rsp);
foo();
return 0;
}
给出:
$ gdb ./a.out
GNU gdb (Gentoo 7.2 p1) 7.2
...
Reading symbols from /home/user/tmp/a.out...done.
(gdb) break foo
Breakpoint 1 at 0x400538: file t.c, line 7.
(gdb) r
Starting program: /home/user/tmp/a.out
RSP: 7fffffffdb90
Breakpoint 1, foo () at t.c:7
7 printf("RSP: %lx\n", rsp);
(gdb) info registers
....
rsp 0x7fffffffdb80 0x7fffffffdb80
....
(gdb) n
RSP: 7fffffffdb80
8 }
从拍摄的的变量指定寄存器中的的文档。
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